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At present, the issue of battery safety has gradually become a hot topic of discussion, especially as more and more people begin to use low-resistance high-power atomizers, battery safety has become more important. At present, the most common type of battery on the market is the 18650 battery we usually use. When it comes to the safety of the 18650 battery, the insulation of the battery is the most important point, let us first talk about some precautions on the battery insulation. Battery daily maintenance In this chapter, we will tell you how you should care for your battery and some of the things you should or should not do. Never do these things: First of all, do not put your battery and some coins or other metal items in the pocket at the same time, the battery and metal items together can easily produce short circuit or battery fluid leakage. In general, the best way is to equip your battery with a special battery holding box, which can maximize the safety of the battery. In addition, never put your battery in your car, the excessive temperature in the car can cause fatal damage to your battery. Also, whenever and wherever, make sure your battery is not exposed to an excessively high temperature environment. Do not charge the battery unattended, so you can beware of any accidents in the charging battery. Using the same type of battery: Another aspect of battery safety is that you should always use the same type of battery in series or parallel. Here are some things you should be aware of when using multiple batteries at the same time. Whether in parallel or in series, the same brand and the same model of battery should be used together. When using multiple batteries in the same device, it should be noted that multiple batteries need to be discharged or charged at the same time to ensure that the battery capacity of multiple batteries is the same. If you can, you can even label the batteries in groups and use them separately. If the batteries originally paired have been used separately, it is best not to pair them again for use. Chemical principle of battery: There are many types of batteries with different chemical principles on the market, and understanding them can better ensure the safety of our batteries. First, the safest is the battery using the IFR principle, the battery uses the lithium iron phosphate (LFP) reaction, which has a weaker chemical reaction than other types of batteries when used. Slightly less safe than IFR batteries are IMR batteries, which use lithium manganese oxide (LMO) reaction, similarly, this type of battery will not have too intense chemical reactions in use. After the IMR battery is the INR battery, the battery usually uses nickel manganese cobalt (NMC), lithium aluminum cobaltate (NCA) or nickel cobalt aluminum (NCA) reaction, such batteries are inferior to IFR, IMR batteries in safety. The last category is the worst safety ICR type of battery, using lithium cobalt oxide (LCO), which has a more intense chemical reaction when used.

Driver should know that, in general, the normal service life of the car battery is 2 to 3 years; However, if the choice is improper or neglectful maintenance, it will lead to premature "lack of power" of the battery and shorten the service life of the product, but in our daily driving, these actions often shorten the service life. 1. The cigarette lighter is in power mode in the flameout state Cigarette lighter is a part that all cars have, which is used to facilitate the ignition source of cigarette lighting when the owner smokes, and the cigarette lighter is to realize the effect of cigarette lighting through the power supply, which is a very important power output interface of the car. In order to improve the convenience and comfort of the car, many owners often use this power interface to connect a lot of equipment, such as GPS, dashcam, air purifier, etc. These devices rely on cigarette lighter power supply to work. The additional electrical equipment itself increases the burden of the battery, and some models of cigarette lighter in the flame-off state is still in power mode, if you do not unplug the external equipment will consume battery power, loss of battery. The general use is maintenance-free lead battery, the general service life is about 3 years. However, if used properly, the service life of a battery can even be extended to 5 to 6 years, of course, if used improperly, the battery is likely to be destroyed in less than 3 years. The reason why there is such a big difference and the owner's daily car habits have a lot to do with. 2, do not turn off the multimedia or air conditioning system before extinguishing Some owners or forget or save time, do not turn off the multimedia system or air conditioning system before the vehicle is turned off, and these systems will automatically open when the vehicle is started next time, which virtually leads to the instantaneous power load of the vehicle is too high, especially the air conditioning is not turned off, which will cause excessive loss of the battery for a long time. 3. Use electricity for a long time after extinguishing Continuing to use electricity after turning off includes many situations, such as using the electrical appliances in the car for a long time after turning off the engine, and forgetting to turn off the lights and so on. At this time, the car's generator is not working, the battery is in a "dry consumption" state without charging, and the reduction of its electrical capacity is likely to cause the vehicle to fail to start, and excessive discharge has great damage to the battery itself. 4, long or frequent ignition When starting the engine each time, the ignition time should not exceed 3 seconds, if the first engine fails to start, do not frequently and repeatedly ignite, it should be ignited again after an interval of 15 seconds, otherwise the battery frequently provides a strong current to the starter, causing its own loss. 5. Do not unplug the external device after extinguishing Now there are more and more external equipment for cars, and the additional electrical equipment itself increases the burden of the battery, and some models of cigarette lighter are still in the power mode in the state of flummox, and the battery is lost.

In order to learn from each other, what processes can be used to modify and optimize silicon? The composite treatment of silicon and other substances can play a better effect, among which the silicon-carbon composite material is a kind of material which has been studied more. Carbon material is currently the most used negative electrode material, carbon material can be divided into soft carbon (graphitized carbon), graphite, hard carbon (amorphous carbon) three kinds, its charge and discharge chemical equation can be expressed as: Carbon anode material has good cyclic stability and excellent electrical conductivity, and lithium ions have no obvious effect on its layer spacing, and can buffer and adapt to the volume expansion of silicon to a certain extent, so it is often used to compound with silicon. Generally, according to the types of carbon materials, composites can be divided into two categories: silicon carbon traditional composite materials and silicon carbon new composite materials. Among them, traditional composite materials refer to silicon and graphite, MCMB, carbon black and other composites, and new silicon-carbon composite materials refer to silicon and carbon nanotubes, graphene and other new carbon nanomaterials composite. According to the distribution mode of silicon, silicon carbon anode materials are mainly divided into coated type, embedded type and molecular contact type, and according to the morphology, they are divided into particle type and film type, and according to the number of silicon carbon types, silicon carbon binary composite and silicon carbon multiple composite. The following figure shows the different distribution of silicon carbon anode materials: The preparation processes of silicon carbon composites include ball milling, high temperature cracking, chemical vapor deposition, sputtering deposition, evaporation and so on. The reversible capacity of the silicon carbon anode prepared by the ball milling method can reach 500~1000mAh/g, and the ball milling can promote the uniform mixing between the raw material particles and obtain a smaller particle size, and the gap between the particles is also conducive to the improvement of the cycle performance of the battery. The high temperature cracking method is a method to obtain Si/C composite materials by cracking nano silicon particles and organic precursors or direct pyrolysis of silicone precursors. The gram capacity of silicon carbon composite materials obtained by this method is lower than that of Si/C composite materials obtained by high-energy ball milling method, but higher than that of graphite, about 300~700mAh/g. This is because the electrode material prepared by pyrolysis method contains a large number of non-electrochemically active substances, which reduces the capacity of the electrode material. Nano-silicon particles have been studied earlier as negative electrode materials, but their large expansion volume effect limits their application. The composite material prepared by the silicon carbon composite reserves the expansion space for the volume expansion of silicon, and makes up for the shortcomings of poor conductivity of silicon and unstable SEI film to a certain extent, and has been widely concerned and applied by cell manufacturers. The famous car manufacturer TESLA launched in 2016, the Modle3 battery cell anode material is silicon carbon anode material, its speed from 0 to 60 miles per hour (about 96.6 kilometers) acceleration only 6 seconds, a range of 215 miles (about 346 kilometers), interested can pay attention to.

The so-called lithium battery is composed of two embeddable and removable lithium-ion data as the positive and negative electrodes of the battery to achieve the repeated charge and discharge function of the secondary battery. Lithium-ion batteries rely on the transfer of lithium ions between the positive and negative electrodes to complete battery charging and discharging operations. As the battery is charged and discharged, Li+ moves between the positive and negative terminals. During discharge, the anode oxidises and loses electrons, while the cathode reduces and gains electrons. During charging, the charge moves in the opposite direction. Lithium-ion batteries are divided into lithium-acid and nickel-acid batteries. Currently, mobile phones and laptops use lithium-ion batteries, commonly known as Li-ion batteries. At present, lithium-ion batteries such as mobile phones are used, and true lithium-ion batteries are not used in everyday electronic products due to their high risk. In the process of embedding and deem bedding of lithium ions, it is accompanied by the embedding and deem bedding of equivalent electrons with lithium ions (it is common for the positive electrode to be represented by embedding or deem bedding, while the negative electrode is represented by insertion or deem bedding). During the charging and discharging process, lithium ions are embedded/deem bedded and inserted/removed between the positive and negative electrodes, which is vividly called a rocking chair battery. Lithium-ion batteries have high energy density and high average output voltage. Self-discharge is low, less than 10% per month. No memory effect. Operating temperature range from -20℃ to 60℃. Excellent cycling performance, fast charge and discharge, up to 100% charge efficiency and high output power. Long service life. No environmental pollution, known as green battery. Lithium-ion Battery Charging Method A. Pre-charging phase. After the DC power supply is turned on, when the Li-ion battery is detected, the charging chip is started to enter the pre-charging process, during which the charging controller charges the battery with a relatively small current so that the battery voltage and temperature return to normal conditions. Constant current stage. At the start of charging, the charging circuit will charge the Li-ion battery at a constant current, and most Li-ion batteries will normally select a standardised charging rate. In constant current charging, the battery voltage will slowly rise, and when the battery voltage reaches the set termination voltage, the constant current charging will be terminated, and then the constant voltage charging process will begin. C. Constant voltage charge. In the process of constant voltage charging, the charging current will gradually decrease, when the monitoring of the charging current falls below the set value or the full charging time timeout into the top cut-off charging, at this time the charge controller will supplement the battery with a very small charging current, under normal circumstances, the process can extend the battery 5%-10% of the use of time.

18650 lithium-ion battery Advantages: 1, the capacity of 18650 lithium-ion battery is generally between 1200mah~3600mah, and the general battery capacity is only about 800mah, if combined into 18650 lithium-ion battery pack, the 18650 lithium-ion battery pack can easily break through 5000mah. 2, long life 18650 lithium-ion battery life is very long, normal use of the cycle life of more than 500 times, is more than twice the ordinary battery. 3, high safety performance 18650 lithium-ion battery high safety performance, no explosion, no combustion; Non-toxic, pollution-free, through RoHS trademark certification; All kinds of safety performance in one go, the number of cycles is more than 500 times; Good high temperature resistance, 65 degrees of power down efficiency of 100%. In order to prevent short circuit of the battery, the positive and negative electrodes of the 18650 lithium-ion battery are separated. So the possibility of a short circuit has been reduced to the extreme. You can install a protection plate to prevent the battery from overcharging and overdischarging, which can also extend the service life of the battery. 4, high voltage 18650 lithium-ion battery voltage is generally 3.6V, 3.8V and 4.2V, much higher than the nickel-cadmium and nickel-metal hydride battery voltage of 1.2V. 5, no memory effect does not have to empty the remaining power before charging, easy to use. 6. Small internal resistance: the internal resistance of the polymer cell is smaller than that of the general liquid cell, and the internal resistance of the domestic polymer cell can even be less than 35m, which greatly reduces the power consumption of the battery, extends the standby time of the mobile phone, and can fully reach the level of international standards. This polymer lithium battery, which supports large discharge currents, is an ideal choice for remote control models and has become the most promising alternative to Ni-MH batteries. 7, can be serialized or combined to synthesize 18650 lithium-ion battery pack 8, use a wide range of laptop computers, walkie-talkies, portable DVDS, instruments, audio equipment, model aircraft, toys, cameras, digital cameras and other electronic equipment. 18650 lithium-ion battery disadvantages: The biggest disadvantage of the 18650 lithium-ion battery is that its volume has been fixed, and it is not very well positioned when it is installed in some notebooks or some products, of course, this shortcoming can also be said to be an advantage, which is a disadvantage compared to other polymer lithium-ion batteries such as lithium-ion batteries can be customized and scalable. And related to some specific battery specifications of the product has become an advantage. 18650 lithium-ion batteries are prone to short circuit or explosion, but also related to polymer lithium-ion batteries, if relatively general batteries, this shortcoming is not so obvious. The production of 18650 lithium-ion batteries must have a protection line to prevent the battery from being overcharged and resulting in discharge. Of course, this is necessary for lithium-ion batteries, which is also a disadvantage of lithium-ion batteries, because the materials used in lithium-ion batteries are basically lithium cobalt acid materials, and lithium-ion batteries of lithium cobalt acid materials can not be large current discharge, and the safety is poor. 18650 lithium-ion battery production conditions are high, related to the general battery production, 18650 lithium-ion battery production conditions are very high, which undoubtedly adds to the cost of production. 18650 Battery life theory for 1000 cycles of charge. Due to the large capacity per unit density, most of them are used for laptop batteries. In addition, 18650 is widely used in major electronic fields because of its excellent stability in work: Commonly used in high-grade light flashlight, portable power supply, wireless data transmission, electric heating warm clothes, shoes, portable instruments, portable lighting equipment, portable printers, industrial instruments, medical instruments and so on.

At present, the issue of battery safety has gradually become a hot topic of discussion, especially as more and more people begin to use low-resistance high-power atomizers, battery safety has become more important. At present, the most common type of battery on the market is the 18650 battery we usually use. When it comes to the safety of the 18650 battery, the insulation of the battery is the most important point, let us first talk about some precautions on the battery insulation. Battery daily maintenance In this chapter, we will tell you how you should care for your battery and some of the things you should or should not do. Never do these things: First of all, do not put your battery and some coins or other metal items in the pocket at the same time, the battery and metal items together can easily produce short circuit or battery fluid leakage. In general, the best way is to equip your battery with a special battery holding box, which can maximize the safety of the battery. In addition, never put your battery in your car, the excessive temperature in the car can cause fatal damage to your battery. Also, whenever and wherever, make sure your battery is not exposed to an excessively high temperature environment. Do not charge the battery unattended, so you can beware of any accidents in the charging battery. Using the same type of battery: Another aspect of battery safety is that you should always use the same type of battery in series or parallel. Here are some things you should be aware of when using multiple batteries at the same time. Whether in parallel or in series, the same brand and the same model of battery should be used together. When using multiple batteries in the same device, it should be noted that multiple batteries need to be discharged or charged at the same time to ensure that the battery capacity of multiple batteries is the same. If you can, you can even label the batteries in groups and use them separately. If the batteries originally paired have been used separately, it is best not to pair them again for use. Chemical principle of battery: There are many types of batteries with different chemical principles on the market, and understanding them can better ensure the safety of our batteries. First, the safest is the battery using the IFR principle, the battery uses the lithium iron phosphate (LFP) reaction, which has a weaker chemical reaction than other types of batteries when used. Slightly less safe than IFR batteries are IMR batteries, which use lithium manganese oxide (LMO) reaction, similarly, this type of battery will not have too intense chemical reactions in use. After the IMR battery is the INR battery, the battery usually uses nickel manganese cobalt (NMC), lithium aluminum cobaltate (NCA) or nickel cobalt aluminum (NCA) reaction, such batteries are inferior to IFR, IMR batteries in safety. The last category is the worst safety ICR type of battery, using lithium cobalt oxide (LCO), which has a more intense chemical reaction when used.

Lithium-ion battery charging and discharging requirements; 1. Lithium-ion battery charging: According to the structure and characteristics of lithium-ion batteries, the maximum charging end voltage is 4.2v, and can not be overcharged, otherwise the battery will be scrapped due to too much positive lithium ions. Its charge and discharge requirements are high, and special constant current and constant voltage chargers can be used for charging. Under normal circumstances, constant current charging is converted to constant voltage charging after 4.2v/knot. When the constant voltage charging current is lower than 100mA, the charging should be stopped. Charging current (mA)=0.1~1.5 times the battery capacity (such as 1350mAh battery, its charging current can be controlled between 135~2025mA). The traditional charging current is about 0.5 times the battery capacity, and the charging time is about 2 to 3 hours. 2. Discharge of lithium-ion batteries: Due to the internal structure of lithium-ion batteries, lithium ions can not be moved to the positive electrode during discharge, and a part of lithium ions in the negative electrode must be kept to ensure smooth insertion of lithium ion channels in the future. Otherwise, the battery life is shortened accordingly. In order to ensure that some lithium ions remain in the graphite layer after discharge, it is necessary to strictly limit the minimum voltage of discharge termination, that is, the lithium ion battery cannot be overdischarged. The discharge termination voltage is generally 3.0V/ node, and the minimum is not less than 2.5V/ node. Battery discharge time is related to battery capacity and discharge current. Battery discharge time (hour)= battery capacity/discharge current. The discharge current (mA) of a lithium-ion battery should not exceed 3 times the battery capacity. (such as 1000mAH battery, discharge current is strictly controlled within 3A) otherwise it will damage the battery. At present, the lithium-ion battery pack sold on the market is equipped with a complete set of charge and discharge protection board. As long as the external charge and discharge current can be controlled. Lithium ion battery protection circuit: The charge and discharge protection circuit of two lithium-ion batteries is shown in Figure 1. The overcharge control tube FET2 and the overdischarge control tube FET1 are connected in series to the circuit. The protection IC monitors and controls the battery voltage. When the battery voltage rises to 4.2v, the overcharge protection tube FET1 stops charging. To prevent misoperation, delay capacitors are usually added to the external circuit. When the battery is in discharge state and the battery voltage drops to 2.55v, disconnect the overdischarge control tube FET1 to stop supplying power to the load. Overcurrent protection means that when a large current passes through the load, the FET1 is controlled to stop discharging to the load to protect the battery and the FET. Overcurrent detection uses the on-resistance of the FET as the detection resistance to monitor its voltage drop, and stops discharging when the voltage drop exceeds the set value. In order to distinguish between surge current and short circuit current, a delay circuit is usually added. The circuit has perfect function and reliable performance, but it is professional, and the special integrated block is not easy to buy, and the layman is not easy to copy.

The discharge capacity is not good, the high temperature performance is poor, the battery is easily damaged and the life is not long. For example, a battery pack of 240 cells in series with a voltage of 480V will reduce its charge by 10% to 432V (or less) when discharged. Whilst providing constant power to the load, this will reduce the current through the battery pack by 10% or more. Although these are simplified examples, greater battery capacity is required to ensure sufficient discharge capacity at the high power discharge rates of data centre applications. However, lithium-ion batteries are the opposite. In general, it has the following advantages: small size, light weight, high energy density, long life, safe to use, high current fast charging, high and low temperature resistance, deep discharge depth, environmentally friendly and no memory effect. However, their initial cost is higher than that of lead-acid batteries. Lithium-ion batteries are relatively new to data centre applications, and people have been looking forward to using lithium-ion battery UPS to achieve longer performance under actual data centre operating conditions. Supercapacitor Although supercapacitor technology has been around for a long time, it has not received much attention in data centre applications because, like the flywheel UPS, it only provides power for a relatively short period of time. It can operate over a wider temperature range (-40F to +150F) than lead-acid and lithium-ion batteries, and is expected to last in excess of 15 years with little manual maintenance. Lithium-ion battery UPS Grid level energy storage In terms of grid level energy storage, its deployment will improve the peak capacity and overall reliability of the grid. In addition, such an approach could improve the ability to integrate sustainable but intermittent energy sources such as solar and wind. Over the past year, there have been several announcements of megawatt-scale grid energy storage using lithium-ion battery UPS to support peak loads, thereby minimising the need for natural gas power plants. Another grid-scale energy storage technology being deployed is vanadium REDOX flow batteries, where energy is stored in a fluid (flowing between two tanks) for charging and discharging.

Lithium Iron Phosphate Battery: The lithium iron phosphate battery refers to a lithium-ion battery that uses lithium iron phosphate as the positive electrode material. The cathode materials of Li-ion batteries include lithium cobalt, lithium manganate, lithium nickel, ternary materials, lithium iron phosphate, and so on. Lithium cobaltate is the anode material used in most Li-ion batteries. Advantages of Lithium Iron Phosphate Batteries: 1, Lithium Iron Phosphate battery life is long, cycle life of more than 2000 times. Under the same conditions, Li-ion Iron Phosphate batteries can be used for 7 to 8 years. 2, safe use. Lithium-Ion Iron Phosphate batteries have passed rigorous safety tests and will not explode even in traffic accidents. 3. Fast charging. Using a special charger, the 1.5C charge can be fully charged in 40 minutes. 4, Lithium Iron Phosphate battery pack high temperature resistance, Lithium Iron Phosphate battery hot air value can reach 350 to 500 degrees Celsius. 5, Lithium Iron Phosphate battery capacity is large. 6, Lithium Iron Phosphate battery has no memory effect. 7, lithium iron phosphate battery green environmental protection, non-toxic, pollution-free, wide source of raw materials, cheap. Lithium-ion batteries: Lithium-ion batteries are a class of batteries using lithium metal or lithium alloy as the negative electrode material and a non-aqueous electrolyte solution. Due to the very active chemical properties of lithium metal, the processing, conservation and use of lithium metal have very high environmental requirements. Therefore, lithium-ion batteries have not been used for a long time. With the development of science and technology, lithium-ion batteries have become mainstream. Advantages of Li-ion Batteries: 1. High energy. It has a high storage energy density, which has reached 460-600Wh/kg, which is about 6-7 times that of lead-acid batteries. 2, long service life, service life can reach more than 6 years, lithium iron phosphate as the positive battery 1C charge and discharge, can be used 10,000 times records; 3, the rated voltage is high, the single working voltage is 3.7V or 3.2V, about equal to the series voltage of 3 nickel cadmium or nickel metal hydride batteries, easy to form a UPS power battery pack; lithium-ion batteries can be adjusted to 3.0V through a new type of lithium-ion battery regulator technology, which is suitable for the use of small electrical appliances; 4, with high power capacity, the lithium-ion iron-phosphate battery for electric vehicles can reach 15-30C charging and discharging capacity, which is convenient for high-strength starting acceleration; 5, the self-discharge rate is very low, which is one of the most prominent advantages of lithium-ion batteries, generally can be less than 1% / month, less than 1/20 of nickel-metal hydride batteries; 6, light weight, the weight of the same volume is about 1/6-1/5 of the lead-acid product; 7, high and low temperature adaptability, can be used in the environment of -20℃ -60℃, after process treatment, can be used in the environment of -45℃; 8, lithium-ion battery green environmental protection, regardless of production, use and scrap, do not contain, do not appear any lead, mercury, cadmium and other toxic and harmful heavy metal elements and substances. 9, the production basically does not consume water, for the shortage of water in our country, very advantageous. The difference between lithium iron phosphate batteries and lithium-ion batteries: 1, iron phosphate lithium-ion battery pack is used to do lithium-ion secondary battery, now the important direction is the power lithium battery, relative to NI-H, Ni-Cd battery has a great advantage. 2, lithium-ion battery is a class of lithium metal or lithium alloy as the positive electrode material, the use of non-aqueous electrolyte solution of the battery. The chemical properties of lithium metal are very active, which makes the processing, conservation and use of lithium metal very high environmental requirements. 3, lithium iron phosphate puncture does not fire does not explode, lithium batteries will.

Electric vehicle lead-acid battery to lithium-ion battery should pay attention to what? How to change their lead-acid electric car battery to lithium-ion battery, can only change the battery? The answer, of course, is no. Now let's look at how to convert a lead-acid battery electric car to a lithium-ion battery. Can lead-acid electric cars replace lithium-ion batteries? It can be converted, but it is not recommended. Here are the details: Lithium-ion batteries for electric cars. 1. As we all know, after the introduction of the new national standard, the standard of electric vehicles has been strictly regulated, which means that the detection of electric vehicles will be more stringent. On the other hand, the company must also have 3C certification and electric motorcycle qualification. Generally speaking, if they switch from lead-acid batteries to lithium-ion batteries, they may face the risk of being taken off the road; 2, when the lead-acid battery replaces the lithium-ion battery, it must also be considered that the voltage must remain the same as the original lead-acid battery, in addition, the charger will also replace the special lithium-ion battery charger, of course, there is a problem, if the lithium-ion battery is improperly installed or there are quality problems, it may burn out the controller, which is not recommended to install one of the reasons; 3, in addition, lead-acid batteries instead of lithium-ion batteries, you must also consider the size of the battery, usually the lead-acid battery compartment is relatively large, and the volume of lithium-ion batteries is relatively small, if you want to change, must consider this factor, if the gap is too large, it is easy to cause vibration after installation in small batteries, reduce the life; 4. Compared with lead-acid batteries, lithium-ion batteries have poor stability. In case of water or improper operation, it is easy to explode. Another point to note is that lithium-ion batteries are multi-chip structures, and as long as there is a problem, the overall quality will be affected. Electric vehicle lead-acid battery to lithium-ion battery should pay attention to what? Volume 1, modify the time to consider the problem of space, in the same capacity, the volume of lithium-ion battery is only half of the lead-acid battery, so of course, but pay attention to some shape and packaging problems, after all, the car space can not only in one direction of the battery, you must consider fixed reliable, prevent vibration drop. In the case of economic conditions, of course, it is hoped that the larger the capacity of the modified lithium-ion battery, the better, so we should make full use of space and choose a reasonable shape of the battery to arrange. If you replace the same capacity of Li-ion batteries because the remaining space is too large, we need to find something to fill the excess space when replacing to prevent the Li-ion battery from falling off while driving. Remove the battery, the battery output positive and negative two lines, very simple, but should also be detailed, wrapped with tape, bare wire, and then pay attention to the positive and negative symbols, so install back again, negative negative details, to prevent the positive and negative haze connected back when working, or accidentally short-circuit the battery positive and negative terminals are negative touch cause safety problems.

Charge-discharge cycle performance of lithium-ion batteries at room temperature At room temperature, after a lithium-ion battery has been charged and discharged according to time, how does it perform during and after this process? This is the improvement direction of lithium-ion battery related technologies, which requires the application of some test parameter interpretation, because the popularity of new energy vehicles in China is accelerating, the selection of large-capacity lithium-ion battery test data collection, help to understand the performance and characteristics of power lithium-ion batteries. Through the test of lithium batteries, the following general conclusions can be drawn: according to the constant current and constant voltage charging stages, the ratio of constant current charging capacity to charging capacity decreases with the increase of the number of cycles; the discharge capacity of 3.7V~4.2V discharge platform accounts for more than 90% of the total discharge capacity, and the charging and discharging efficiency is not affected by the number of cycles. Here is a detailed description. Before describing the data, it is necessary to explain the test environment: BYD 80Ah lithium cobalt oxide battery is selected for the charge and discharge test at room temperature (10℃~250℃). Charge and discharge system design: The charge is constant current and constant voltage. First, charge to 4.2V at 1C or 80A constant current. 2.10 minutes later, use 80A constant current to 2.75V; 3. After 10 minutes of continuous discharging, perform a new round of charge and discharge cycle, repeat 500 times. During this process, the relevant data should be collected to form the appropriate graph: constant current/constant voltage charge characteristic curve; 2.2. The relationship between the ratio of constant current charge capacity to total charge capacity and the number of cycles; 3. the discharge curve; 4. the charge and discharge efficiency curve. As can be seen in the figure above: 1. Starting from the constant current charging stage, the charging platform of lithium-ion batteries is 3.8V~4.1V, and the charging capacity of this stage accounts for more than 80% of the total charging capacity. As the number of cycles increases, the voltage rise speed is accelerated, the charging time is shortened and the charging amount is gradually reduced. 2. As the number of cycles increases, the percentage of constant current charge capacity in the total charge capacity decreases, and the percentage of constant voltage charge capacity in the total charge capacity increases. This shows that as the number of charge and discharge cycles of Li-ion batteries increases, the lower the current, the better the charging effect. 3. According to the discharge curve, the discharge platform (the discharge curve is stable in a certain voltage range, close to a straight line, rather than the distance between the previous rising and falling slope line) with the increase of the number of cycles, and 4.2V~3.7 published discharge platform accounts for 90% of the total electricity. 4. Charge and discharge efficiency: that is, the percentage of released electricity to charge electricity. Indicates the discharge capacity of the battery, from the charge-discharge efficiency curve, the value remains basically unchanged, reaching more than 99%. We understand that the capacity of LiFePO4 Battery decreases as the number of charge and discharge cycles increases, which can be seen from the above data. The specific performance is that the discharge platform is reduced, the lithium-ion battery charging time is reduced and the constant current charging ratio is reduced. The final performance is that the charge capacity decreases with the number of new cycles, and the rate of decrease becomes faster and faster. After 500 cycles, the capacity must be at least 80% to qualify.

LiFePO4 battery, or LFP battery, the full name is the lithium iron phosphate battery, which belongs to one kind of rechargeable lithium batteries, battery takes LiFePO4 as cathode materials. For original LiFePO4 have low electric conductivity, many battery manufacturers make efforts on improving original LiFePO4 materials, like nano-technology, metal-doping, carbon-coating etc. Takes metal-doping and carbon-coating to update original LiFePO4 materials for battery manufacturing. What is the Amp-hour (AH)? The Amp-hour (Ah) is used for describing how much energy that battery can store in. The volume of the constant current (in amps) multiple with time (in hours) then got Amp-hour (AH) as battery capacity. For example, if a Forzatec LiFePO4 cell, marked as "10AH @ 3C discharge, 25°C", it means in 25°C condition, if we discharge this battery with current no more than 30A (10AH, 3C), this battery can offer 10AH energy, like 30A current for 1/3 hour, or 5A current for 2 hours. What is state of charge (SOC)? SOC, short for the State of Charge, is used to describe how full a battery is. When a battery is fully charged, we can say that the SOC of this battery is 100%. SOC can be used to describe how fully the lead acid battery charged, because lead acid battery always need to be fully charged for storage. Later nickel batteries and lithium batteries also take SOC to describe energy reserve. Here is a formula describing the relationship of SOC and DOD, that is "SOC = 100% - DOD". What is depth of discharge (DOD)? DOD, short for the Depth of Discharge, is used to describe how deeply the battery is discharged. If we say a battery is 100% fully charged, it means the DOD of this battery is 0%, If we say the battery have delivered 30% of its energy, here are 70% energy reserved, we say the DOD of this battery is 30%. And if a battery is 100% empty, the DOD of this battery is 100%. DOD always can be treated as how much energy that the battery delivered. For lithium batteries we do not suggest fully discharge them to 100% DOD, because it would shorten the cycle life of batteries. What is self-discharge rate? The self-discharge rate is a measure of how much batteries discharge on their own. The Self-Discharge rate is governed by the construction of the battery. Different types of batteries have different self-discharge rate. What is CC/CV mode? Constant current / constant voltage (CC/CV) charging mode is a effective way to charge lithium batteries. When a lithium battery is nearly empty, we take constant current to charge it. We need to make sure that charging current should be lower than the max charging current that battery can accepted. With constant charing the voltage of battery is slowly gaining up, when battery volt reaches the max charging voltage, charger would make sure charging voltage fixed as "constant voltage" and reduce the charging current. When battery is fully charged this state would be stopped. What is Battery cycle life? Battery cycle life is defined as the number of complete charge - discharge cycles a battery can perform before its nominal capacity falls below 80% of its initial rated capacity. Different types of batteries have different cycle life, and LiFePO4 batteries life time of 2000 cycles are typical. How to extend the battery cycle life? Singal cell is an independent unit which contains a complete chemical reaction environment inside. For nominal usage we need to make sure that cells / batteries are under specified conditions that data-sheet described. For lithium batteries, we suggest to take consideration of working temperature, and do not fully charged to 100% SOC and do not fully discharged to 100% DOD when using, and by maintaining the battery this way the cycle life of LiFePO4 could be effectively extended.

There are three reasons: First, the copper-aluminium foil has good conductivity, soft texture and cheap price. As we all know, the working principle of lithium batteries is an electrochemical device that converts chemical energy into electrical energy, so in this process we need a medium to transfer the electrical energy converted from chemical energy, here we need conductive materials. In ordinary materials, metal materials are the best materials for electrical conductivity, and in metal materials, the price is cheap and the conductivity is good: copper foil and aluminium foil. At the same time, in lithium batteries, we mainly have two processing methods: winding and laminating. Relative to the winding, the electrode sheet used for the preparation of the battery must have a certain softness to ensure that the electrode sheet in the winding will not cause brittleness and other problems, and the metal material, copper aluminium foil is also a soft metal. Finally, consider the cost of battery preparation, relatively speaking, the price of copper aluminium foil is relatively cheap, and the world's copper and aluminium resources are rich. Second, the copper-aluminium foil is also relatively stable in air. Aluminium is easy to chemically react with oxygen in the air, forming a dense oxide film on the surface layer of aluminium to prevent further reaction of aluminium, and this thin oxide film also has a certain protective effect on aluminium in the electrolyte. Copper itself is relatively stable in air and does not generally react in dry air. Thirdly, the positive and negative potentials of lithium batteries determine the positive electrode with aluminium foil and the negative electrode with copper foil, not the other way round. The positive electrode potential is high, and the copper foil is easily oxidized at high potential, while the oxidation potential of aluminium is high, and the surface layer of aluminium foil has a dense oxide film, which also has a good protective effect on the internal aluminium. For lithium-ion batteries, the positive collector fluid is usually aluminium foil and the negative collector fluid is copper foil, and to ensure the stability of the collector fluid in the battery, the purity of both is required to be over 98%. With the continuous development of lithium technology, whether it is used for lithium batteries of digital products or batteries of electric vehicles, we all hope that the energy density of the battery is as high as possible, the weight of the battery is getting lighter and lighter, and the most important thing in the fluid collection is to reduce the thickness and weight of the fluid collection, and intuitively reduce the volume and weight of the battery. Copper-Aluminium Foil Thickness Requirements for Lithium Batteries With the rapid development of lithium batteries in recent years, the development of fluid collectors for lithium batteries has also been rapid. The positive aluminium foil has been reduced from 16um in previous years to 14um and then to 12um, and now many battery manufacturers have mass-produced 10um and even 8um aluminium foils. The negative copper foil, due to the good flexibility of copper foil, its thickness is reduced from the previous 12um to 10um, and then to 8um, so far a large number of battery manufacturers use 6um in mass production, and some manufacturers are developing 5um/4um is possible to use. Since the lithium battery has high purity requirements for the copper-aluminium foil used, the density of the material is basically at the same level, and with the reduction of the development thickness, the surface density is also correspondingly reduced, and the weight of the battery naturally becomes smaller and smaller, which meets our requirements for lithium batteries. Copper-Aluminium Foil Surface Roughness Requirements for Lithium Batteries For the fluid collector, in addition to its thickness and weight having an impact on the lithium battery, the surface performance of the fluid collector also has a greater impact on the production and performance of the battery. In particular, due to the shortcomings of the preparation technology, the copper foils on the market are mainly single-sided wool, double-sided wool and double-sided coarse-coated varieties. The asymmetric structure of the two sides leads to asymmetric contact resistance of the coating on both sides of the negative electrode, so that the negative capacity of both sides cannot be released evenly. At the same time, the asymmetry of both sides also causes the adhesion strength of the negative coating to be uneven, and the charge-discharge cycle life of the negative coating on both sides is seriously unbalanced, accelerating the degradation of battery capacity.

Polymer lithium-ion battery generally refers to polymer lithium-ion battery, according to the different electrolyte materials used in lithium-ion battery, lithium-ion battery is divided into liquid lithium-ion battery and polymer lithium-ion battery or plastic lithium-ion battery. Do you know the difference between polymer lithium battery and lithium battery? Find out below. First, the difference between polymer lithium batteries and lithium batteries Compared to lithium-ion batteries, the characteristics of lithium polymer batteries are as follows: 1. No battery leakage problem, the battery does not contain liquid electrolyte, the use of colloidal solid. 2. Can be made into thin battery: with a capacity of 3.6V400mAh, its thickness can be as thin as 0.5mm. 3. Batteries can be designed in a variety of shapes. 4. The battery can be bent and deformed: the maximum bending of the polymer battery is about 900. 5. Can be made into a single high voltage: liquid electrolyte batteries can only be a number of batteries in series to obtain high voltage, polymer batteries. 6. Because it has no liquid, it can be made into several layers in a single piece to achieve high voltage. 7. The capacity is twice that of lithium-ion batteries of the same size. Second, polymer lithium battery life Correct statement: the life of a lithium battery is related to the completion of the charge cycle and not the number of charges. For example, a lithium battery is charged half on the first day and then fully charged. If it is still the same the next day, you will have used half the charge, for a total of two discharges, which can only be counted as one charge cycle, not two. Therefore, it may normally take several charges to complete a cycle. Each time you complete a charge cycle, the charge is reduced slightly. However, the reduction is very small, high-quality batteries after multiple cycles, will still retain 80% of the original power, many lithium power supply products are still used as usual after two or three years, is the reason. Of course, lithium batteries will eventually need to be replaced. The life of a lithium battery is generally 300 to 500 charge cycles. Assuming that the amount of electricity provided by a full discharge is Q, and not taking into account the reduction in electricity after each charge cycle, the lithium battery can provide or replenish 300Q-500Q of electricity in its lifetime. From this we know that if you charge at 1/2 every time, you can charge 600-1000 times; if you charge at 1/3 every time, you can charge 900-1500 times. Similarly, if you charge randomly, the number of times will vary. In short, no matter how it is charged, the total amount of power added to 300Q ~ 500Q is constant. Therefore, we can also understand that the life of a lithium battery is related to the total charge of the battery and has nothing to do with the number of times it is charged. Deep discharge, shallow discharge and shallow charge have little effect on the life of a lithium battery. If lithium is used in an environment above the specified operating temperature, i.e. 35°C, the performance of the battery will continue to deteriorate, i.e. the battery will not last as long as usual. If you charge the device at such a temperature, the damage to the battery will be greater. Even if the battery is stored in a hot environment, it will inevitably damage the quality of the battery. Therefore, trying to maintain a suitable operating temperature is a good way to extend the life of lithium batteries. If lithium is used in a low temperature environment, i.e. below 4°C, you will also find that the battery life is reduced, and the original lithium battery in some mobile phones cannot even be charged in a low temperature environment. But don't worry too much, this is only a temporary situation, unlike the use of high temperature environment, once the temperature rises, the molecules in the battery are heated and immediately return to the previous charge. To maximise the performance of lithium-ion batteries, it is necessary to use them frequently so that the electrons in the lithium battery are always in a state of flux. If you do not use lithium very often, please remember to complete a lithium charge cycle every month and to perform a performance calibration, i.e. a deep charge.

If the motor and control technology is proven and increasingly mature, the most difficult dilemma and the biggest competition for electric vehicles comes from battery technology. The future of electric vehicles is silence and patience. But China and the West at the top of the wave, BYD and Tesla, have something to say. Tesla in the early electric sports car Roadster, the use of very small 18650 lithium cobalt acid battery, this battery is usually used in mobile phones, laptops and other small electrical appliances. Its main feature is that it has a very high energy density, almost 170 watt-hours/kg. But its thermal stability is also criticised, at around 180 degrees a decomposition phenomenon occurs and oxygen is produced. Later, in order to compromise energy density, power density and safety, Tesla used modified ternary nickel-cobalt-aluminium batteries in the Model S. This brought the total number of batteries to more than 8,000, more than 1,000 more than in the Roadster, but the cost was reduced by 30%. However, the very limited number of cycles is still a problem that limits the use of such batteries in electric vehicles; with a charging frequency of once every two days, the battery will be dead after about three to four years. Tesla's solution to this problem is to offer a "no-fault" battery warranty, which means that as long as the battery is not damaged by human error or collision, you get eight years of free warranty. At the end of that period, Tesla will be responsible for recycling and replacing the battery. Such a policy will put a lot of pressure on Tesla as it introduces entry-level models and increases sales. This may be one reason why the company is preparing to build the world's largest battery factory. By contrast, the lithium-iron-phosphate battery used by BYD is currently a more widely used battery. Its advantage is that its thermal stability is very high, the structure is still relatively stable at 600 degrees, and because the trivalent iron ion is not active, it is difficult to chemically change, which makes its life relatively long, theoretically longer than the life of the vehicle, and the cost of long-term use is low. At the same time, the power density of the lithium iron phosphate battery is relatively good, and it can be discharged at a high rate and has good acceleration performance. However, compared with the ternary lithium battery, the energy density of lithium iron phosphate battery does not have an advantage, about 100 to 110 watt-hours/kg, which leads to a shorter range under the same weight conditions, want to achieve a higher range, it is inevitable to increase the weight of the battery, increase the cost. From a comprehensive performance point of view, not all companies have Tesla's software and battery management capabilities, so lithium iron phosphate batteries are still more optimistic and pragmatic battery types. This may also be one of the reasons why GE is willing to use lithium iron phosphate batteries. Due to the characteristics of the battery, Tesla has made a very thorough design of the battery layout, thermal management system and battery management system to ensure that each battery unit is monitored and its status data can be fed back and processed at any time. For a single small battery unit, Tesla will be independently enclosed in a steel compartment, while the liquid cooling system can be specific to each battery unit to cool, reduce the temperature difference between each other, but also relatively reduce the risk of spontaneous combustion of the battery. The Tesla accident was largely caused by the local short-circuit of the power line caused by the puncture of the battery pack. At present, Tesla cannot solve the situation of combustion and explosion caused by extreme damage to the battery pack by the impact force, but the high-intensity protection has won more time for the owner to escape. In fact, this is almost a common potential hidden danger of electric vehicles, which places very high demands on the functioning of the battery management system. In addition to daily monitoring of the battery temperature and operating status, it is also necessary to immediately disconnect the high-voltage cable in the event of rapid temperature changes or an extreme collision. The improvement of the thermal management system and the battery management system will also shorten the battery charging time and bring higher charging efficiency. In addition, how to ensure the efficiency of battery charging and use in a low-temperature environment is a problem that needs to be solved by companies involved in the R&D and production of electric vehicles. In addition, it should be mentioned that Tesla has been promoting pure electric vehicle products, and its high-end route from high to low product ideas also reflects that the market inclusiveness of electric vehicles is far from enough. BYD's future plans to promote "dual-engine, dual-mode" vehicles is actually to promote plug-in hybrid cars as a transitional product before the electric market really opens up. Compared with traditional petrol cars, hybrid cars are more fuel efficient and reduce battery consumption, and taking into account the policy subsidies for new energy vehicles, the cost of purchasing cars has also been reduced, which is in line with BYD's civilian product ideas.

Causes of lithium battery ageing Aging generally refers to the placement of the battery after the first charge after assembly, which can be normal temperature aging or high temperature aging, all functions are to make the performance and composition of the SEI film formed after the first charge stable. The normal temperature aging temperature is 25℃, and the high temperature aging facilities are different, some have 38℃ and 45℃. Between 48 and 72 hours. Aging, sealing two cases: For batteries that form holes, the relative humidity is controlled below 2% at room temperature, and the sealing effect is better after aging. For high temperature aging, the sealing aging effect is better. However, it is certain that there are electrochemical dynamic changes in the ageing process, which is of great help to the stability of the SEI and can promote the stability of the electrochemical system. Causes of lithium-ion battery ageing Aging generally refers to the placement of the battery after the first charge after assembly, which can be normal temperature aging or high temperature aging, all functions are to make the performance and composition of the SEI film formed after the first charge stable. The normal temperature aging temperature is 25℃, and the high temperature aging facilities are different, some have 38℃ and 45℃. Between 48 and 72 hours Aging, sealing two cases: For batteries that form holes, the relative humidity is controlled below 2% at room temperature, and the sealing effect is better after aging. For high temperature aging, the sealing aging effect is better. However, it is certain that there are electrochemical dynamic changes in the ageing process, which is of great help to the stability of the SEI and can promote the stability of the electrochemical system. At present, most battery companies use domestic inferior diaphragms for mass production, and high-temperature aging has become an unwritten requirement for safety testing of battery internal structures. High temperature aging is only to shorten the entire production cycle of the battery, the player only enters the battery at high temperature to accelerate the chemical reaction, the battery is not more than the benefits may damage the battery, it is best to incubate at room temperature for more than three weeks, we are negative, the separator, enough electrolyte balance and other chemical reactions, and then the battery performance is more real. This is often the case with lithium-ion batteries because they can only be charged and discharged a limited number of times, so you should try to fully charge your phone's battery. However, I did find an experimental chart on the charge/discharge cycle of lithium-ion batteries, and the cycle life data is as follows Cycle life :10%DOD>1000 times, 100%DOD Cycle life :>200 times, where DOD is the abbreviation for depth of discharge. As can be seen from the table, the rechargeable time is related to the depth of discharge, and the cycle life of 10%DOD is much longer than that of 100%DOD. Of course, when reduced to the actual total charge capacity: 10%*1000=100,100%*200=200. The latter is still relatively good to fully charge and discharge, but before the idea to do some revision: under normal circumstances, you should have an appointment, according to the principle that the remaining battery power is used up before charging, but if your battery is not expected to stick to the whole day on the second day, you should start charging in time, of course, if you are willing to carry the charger back to BieLun The office.

There are two categories of batteries for electric vehicles, batteries and fuel cells. Batteries suitable for pure electric vehicles include lead-acid batteries, nickel-cadmium batteries, nickel-metal hydride batteries, sodium-sulphur batteries, secondary lithium batteries, and air batteries. Among them, lead-acid batteries, nickel-cadmium batteries and nickel-metal hydride batteries appeared earlier, and have generally been eliminated as battery types, and today's mainstream pure electric vehicles are basically lithium batteries, mainly including lithium cobalt acid batteries, such as Tesla products; lithium manganate batteries, such as Toyota Prius, Nissan Leaf; lithium iron phosphate batteries, such as BYD products, Zhinuo 1E, etc. Lead acid battery is the most commonly used battery in new energy vehicles. The plate of lead-acid battery is a grid made of lead alloy, the electrolyte is dilute sulfuric acid, and the two plates are covered with lead sulfate. However, after charging, the lead sulphate on the plate at the positive electrode is converted to lead dioxide, and the lead sulphate at the negative electrode is converted to metallic lead. When the battery is discharged, a chemical reaction takes place in the opposite direction. The advantage of lead-acid batteries is that the electromotive force is more stable when discharged, the disadvantage is that the energy is low and the environment is corrosive. Nickel-metal hydride batteries are widely used in new energy hybrid vehicles, which have a high energy density ratio and can effectively extend the driving time of vehicles. In addition, nickel-metal hydride batteries have smooth discharge characteristics, smooth discharge curve, small calorific value but large volume and pollution. Compared with lead-acid and nickel-metal hydride batteries, lithium-ion batteries have advantages such as high operating voltage, high specific energy, small size, light weight, long cycle life, low self-discharge rate, no memory effect and no pollution. Therefore, more and more automobile manufacturers are choosing lithium-ion batteries as the power batteries for pure electric vehicles. There are three most commonly used lithium-ion batteries, which are lithium cobalt acid batteries, lithium manganese acid batteries and lithium iron phosphate batteries. The lithium cobalt acid battery has high efficiency, large discharge current, high charging speed and light weight, but the disadvantage is that the stability is relatively poor, which is why this battery technology is difficult to manufacture large capacity battery cells. The lithium manganese acid battery costs slightly less and is not as radical as lithium cobalt acid, the low temperature performance is better, more suitable for use in cold areas, but the high temperature stability is not good enough, easy to bulge, and the cycle life declines faster. Lithium iron phosphate batteries are known as the safest automotive battery technology, because compared with lithium cobalt acid batteries and lithium manganese acid batteries, the stability of lithium iron phosphate batteries, especially at high temperatures, is much more stable, and the chance of accidents such as fire is less. However, lithium iron phosphate batteries are not as efficient as these two battery technologies, and the weight required to store the same amount of energy is about twice that of lithium cobalt oxide batteries, so it is no wonder that this new battery technology has been a difficult choice for high performance electric sports cars.

In recent years, the frequent occurrence of electric vehicle fires caused by battery safety problems has become an undeniable fact, making the large number of consumers who have doubts about electric vehicles more resistant. The cause is that overcharging, overheating, electrical triggering, collision and other factors can lead to thermal runaway of the power battery. The cause of thermal runaway is related to the improper selection and thermal design of the battery, or the external short circuit causes the temperature of the battery to rise, or the connector of the cable to loosen. It can be solved from two aspects of battery design and management, such as the development of materials to prevent thermal runaway reaction, etc. For battery management, different temperature ranges can be predicted to define safety levels. In addition, different batteries have very different levels of safety. For example, in the event of a collision, the safety of lithium iron phosphate is higher than that of ternary lithium electronic batteries, but so far we still insist on using lithium iron phosphate batteries in buses, and it is not suitable for large-scale use of ternary lithium electronic batteries, especially 12-metre buses. If domestic battery companies want to make a breakthrough in safety issues, they should also study the safety design of Tesla batteries. Objectively speaking, Tesla's batteries are not safe, at least not individually. However, the unsafe individual battery can achieve system safety because Tesla uses more than 7,000 18650 ternary nickel-cobalt lithium batteries, and the combination of unsafe batteries is safe. It also became a patent for Tesla's safety design.

The internal composition of lithium battery is mainly positive electrode | electrolyte | diaphragm | electrolyte | negative electrode, on this basis, the electrode ear welding, packaging and other steps finally form a complete cell. After the initial charge and discharge of the battery cell, the chemical component capacity and exhaust and other steps, it can be used in the factory. The first step in this process is the selection of materials. The main factors affecting the safety of the material are its intrinsic orbital energy, crystal structure and material properties. Positive electrode material The main role of the positive active material in the battery is to contribute to the specific capacity and specific energy, and its intrinsic electrode potential has a certain impact on safety. For example, in recent years, China has widely used the low-voltage material LiFePO4 (lithium iron phosphate) as a positive electrode material for power batteries in transportation vehicles (such as hybrid electric vehicle HEV, electric vehicle EV) and energy storage devices (such as uninterruptible power supply UPS). However, the safety advantages of LiFePO4 in many materials actually come at the expense of energy density, which means that the battery life of its users (such as EV, UPS) will be limited. Ternary materials such as NMC(LiNixMnyCo1-x-yO2) have excellent energy density performance, but as an ideal cathode material for power batteries, the safety issue has not been fully resolved. To study the thermal behaviour of cathode materials, researchers have done a lot of work and found that the intrinsic electrode potential and crystal structure are the main factors affecting its safety, such as whether the electrode potential μC and the highest occupied orbital HOMO of the electrochemical window of the electrolyte are perfectly matched, and whether multiple lithium ions can pass smoothly through the lattice at the same time. The safety performance of positive active materials can be improved by the choice of material type and element doping. Negative electrode material The influence of the negative active material on the safety performance is mainly due to the relationship between its intrinsic orbital energy and the configuration of the electrolyte LUMO and HOMO. In the process of fast charging, the speed of lithium ion through the SEI (Solid Electrolyte Interface) film may be slower than the deposition rate of lithium in the negative electrode, and the lithium branch crystals will grow continuously with the charge and discharge cycle, which may lead to internal short circuit and ignite the combustible electrolyte thermal runaway, limiting the safety of the negative electrode in the fast charging process. Only when the difference between the negative electromotive force of the lithium alloy with carbon material as a buffer layer and the electromotive force of lithium is less than -0.7Ev, i.e. μA<μLi0.7eV, can it be guaranteed that the deposition of lithium will not cause a short circuit. For safety reasons, the power battery should use a negative electrode material with an electromotive force of less than 1.0eV (relative to Li+/Li0) to achieve safe fast charging or to control the charging voltage well below the deposition potential of lithium. Li4Ti5O12 has safety advantages in fast charging and fast discharging due to its electromotive force of 1.5eV (relative to Li+/Li0), which is lower than the LUMO of the electrolyte. There is also a negative material, Ti0.9Nb0.1Nb2O7, which can be rapidly charged and discharged for more than 30 weeks at a voltage of 1.3≤V≤1.6V (relative to Li+/Li0) and has a specific capacity of 300mAhg1, which is higher than LTO. During the discharge process, since there is no competition between the speed of lithium ions through the SEI film and the deposition on the negative electrode, the fast discharge process is safe.

As we all know, the positive substrate of Lithium Iron Phosphate Battery is aluminium foil and the negative substrate is copper foil, which are coated and formed into positive electrode sheet rolls and negative electrode sheet rolls for the next step. The quality of the electrode has basically determined some of the performance of the battery, and the coating of the substrate is a very important part of the entire battery manufacturing process! Coating method from the original dip coating, extrusion development to the current most advanced double-sided coating, all to improve the coating quality and performance of the pole film, some domestic economic strength of the unit, in order to produce reliable performance of LiFePO4 Battery, chemical costs a lot of money to introduce expensive foreign pole film coating machine. The general process of coating: the coating substrate (metal foil) is released from the unwinding device to the coater. The end and the beginning of the substrate are joined into a continuous strip by the drawing device into the tension adjustment device and the automatic correction device, and after adjusting the tension and position of the strip into the coating device. The pole sheet is coated in sections in the coater according to the predetermined coating amount and blank length. When coating both sides, the front coating and blank length are automatically tracked for coating. The coated wet pole sheet is sent to the drying channel for drying and the drying temperature is set according to the coating speed and coating thickness. The dried pole sheet is rewound after tension adjustment and automatic correction for the next step. The polar sheet slurry coating is relatively thick, the amount of coating is large and the drying load is high. At present, hot air impact drying technology is commonly used. The positive substrate is aluminium foil, and the chemical properties of aluminium foil are very active and easily oxidised. In the manufacturing process of aluminium foil will form a dense oxide film, prevent the further oxidation of aluminium foil, because the oxide film is thin and porous, soft, with good adsorption, but high temperature and high humidity can destroy this layer of oxide film, accelerate the oxidation reaction. At present, most of them are single-sided coating, when the first side is coated, the other side is completely exposed to the hot air, and the hot air of the coating (oil system) is dry at about 130 ° C, such as the water content of the hot air is not effectively controlled, which will increase the oxidation of aluminium foil and affect the adhesion of the positive electrode material with the aluminium foil, and even cause falling off. The United States, Japan coating mechanism manufacturers for single-layer coating performance and aluminium foil oxidation problems, the development of double-sided coating technology, completely solve the problem of aluminium foil oxidation during coating, but the price of double-sided coating machine is not the general battery manufacturers can afford.