Why is the ternary lithium battery more suitable for household electric vehicles?

　　1. Low temperature discharge performance is better

　　my country is vast and the climate is complicated. From the northeast three northeast provinces to the southernmost Hainan islands, the temperature changes are very rich. Taking Beijing as an example, as the main market for electric vehicles, the highest temperature in Beijing in summer is about 40 ° C, while in winter, it is basically maintained at minus 16 ° C or even lower. Such a temperature range is obviously suitable for a ternary lithium battery with better low temperature performance. The lithium iron phosphate battery that focuses on high temperature resistance will appear a little weak in winter in Beijing.

　　"Relatively 25 ° C capacity" refers to the ratio of discharge capacity at different temperature conditions to the discharge capacity at 25 ° C. The value can accurately reflect the attenuation of the battery life under different temperature conditions. The closer to 100%, the better the battery performance.

　　It can be seen from the figure above that at 25 ° C as the benchmark room temperature, the two types of batteries discharge at 55 ° C and discharge at a normal temperature at 25 ° C. There is almost no difference in discharge capacity. However, at minus 20 ° C, the ternary lithium battery has a relatively obvious advantage compared with the lithium iron phosphate battery.

　　Second, the energy density is higher

　　According to the data provided by the Biking Battery, which is a leading company in the domestic ternary material 18650 cylindrical battery, the energy density of its 18650 battery has reached 232Wh/KG, and it will further increase to 293WH/KG. In contrast, the energy density of lithium iron phosphate battery in China is currently only about 150Wh/KG. According to the analysis of experts in the domestic battery industry, in the next few years, the energy density of lithium iron phosphate batteries can reach 300WH/kg of 300WH/kg Hope is very slim.

　　Different from the huge electric bus, the space is always the first for home electric vehicles. Lithium iron phosphate batteries with low energy density will occupy the uncomfortable car space, and due to the heavier quality, the battery life of discharge during use will also be greatly affected. Relatively speaking, the ternary lithium battery with higher energy density also saves room for household cars while solving the problem of weight.

　　Third, higher charging efficiency

　　In addition to battery life, charging is also an important part of electric vehicles in actual use, while ternary lithium batteries have a very large advantage in charging efficiency than lithium iron phosphate batteries.

　　At present, the more common charging methods on the market are constant streaming and constant voltage charging. Generally, constant current charging is used at the beginning of the charging. At this time, the current is large and the charging efficiency is relatively high. After the voltage reaches a certain value, the reduction of the current to constant voltage charging, which can make the battery fill more. In the process, the ratio of the constant current charging capacity to the total battery capacity is called the constant current ratio. It is a key value that measures a set of battery charging efficiency during the charging process. The larger the percentage, the higher the power charging in the constant current stage, which proves that the battery's charging efficiency is higher.

　　It can be seen from the table that when the ternary lithium battery and the lithium iron phosphate battery are charged below 10C, there is no significant gap between the constant current ratio. When the multiplier of 10C is charged, the percentage of the constant current of the lithium iron phosphate battery is rapidly reduced, and the charging efficiency is rapidly reduced.

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