Which is more advantageous in performance comparison between lithium iron phosphate lithium battery and ternary lithium battery?

The so-called lithium iron phosphate battery refers to a lithium battery that uses lithium iron phosphate as a positive electrode material. The characteristic of this type of battery is that it does not contain precious metal elements (such as cobalt, etc.). In actual use, lithium iron phosphate batteries have the advantages of high temperature resistance, strong safety and stability, low price, and better cycle performance. The ternary material lithium battery refers to a lithium battery that uses lithium nickel cobalt manganate as the positive electrode material and graphite as the negative electrode material. Unlike lithium iron phosphate, the ternary lithium battery has a high voltage platform, which means that under the same volume or weight, the specific energy and specific power of the ternary lithium battery are greater. In addition, ternary lithium batteries also have great advantages in terms of high-rate charging and low-temperature resistance. The nominal voltage of iron-lithium is 3.2-3.3V, and that of manganese is 3.6-3.7V. This is the most obvious difference. Advantages of the iron-lithium system: long theoretical life, excellent theoretical resistance to overcharge and overdischarge. The advantages of the ternary system: high energy density, good low temperature performance, small size, and good discharge linearity. Disadvantages of iron-lithium: large volume, heavy weight, poor discharge linearity, and poor low-temperature performance. Disadvantages of the ternary system: slightly poor cycle life, poor life under high temperature conditions. When it comes to batteries alone, there is no such thing as who is better and who is worse. It is just applied to actual use scenarios. Compared with lithium iron phosphate batteries, ternary lithium batteries are more suitable for current and future household electric vehicles. Ternary material batteries are more suitable for passenger cars and have better low-temperature discharge performance. my country has a vast territory and a complex climate. The temperature changes from the northernmost three provinces in Northeast to the southernmost islands of Hainan. Take Beijing as an example. As the main market for electric vehicles, the highest temperature in Beijing in summer is around 40°C, while in winter it basically stays at around minus 16°C or even lower. Such a temperature range is obviously suitable for ternary lithium batteries with better low-temperature performance. However, lithium iron phosphate batteries, which value high-temperature performance, will look a little weak in winter in Beijing. Relative 25℃ capacity refers to the ratio of discharge capacity under different temperature conditions to discharge capacity at 25℃. This value can accurately reflect the attenuation of battery life under different temperature conditions. The closer to 100%, the better the battery performance. It can be seen from the above figure that, taking 25°C as the reference room temperature, the two types of batteries are discharged at a high temperature of 55°C and discharged at a normal temperature of 25°C, and there is almost no difference in discharge capacity. But at minus 20°C, ternary lithium batteries have clear advantages compared with lithium iron phosphate batteries. Higher Energy Density According to the information supplied by BAK Battery, the leading company in the domestic ternary material 18650 cylindrical battery, the energy density of its 18650 battery has reached 232Wh/kg, and will be further increased to 293Wh/kg in the future. In contrast, the energy density of the current domestic mainstream lithium iron phosphate batteries is only about 150Wh/kg. According to the analysis of domestic battery industry experts, the energy density of lithium iron phosphate batteries can reach 300Wh/kg in the next few years. Hope is very slim. Unlike the bulky electric buses, for household electric vehicles, space always comes first. Lithium iron phosphate batteries with lower energy density will occupy a small amount of car space, and due to the heavier mass, the discharge life during use will also be greatly affected. Relatively speaking, the ternary lithium battery with higher energy density can not only deal with the weight problem, but also save space for the family car. Higher charging efficiency In addition to battery life, charging is also an important part of the actual use of electric vehicles, and the ternary lithium battery has a very big advantage over the lithium iron phosphate battery in terms of charging efficiency. The most common charging method currently on the market is constant current and constant voltage charging. Generally, constant current charging is used at the beginning of charging. At this time, the current is larger and the charging efficiency is relatively higher. After the voltage reaches a certain value, reduce the current and change to constant voltage charging, so that the battery can be charged more fully. In this 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 to measure the charging efficiency of a group of batteries during the charging process. Generally, the larger the percentage, the higher the amount of electricity charged in the constant current stage, which also proves that the battery has a higher charging efficiency. 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 clear difference in the constant current ratio. When the rate is above 10C, the constant current ratio of the lithium iron phosphate battery decreases rapidly, and the charging efficiency decreases rapidly. Cycle life is guaranteed. For family cars, the rated cycle life of ternary materials and lithium iron phosphate power lithium-ion batteries far exceeds the actual user's habits, so you can rest assured in terms of service life. Taking the current high-capacity 18650 battery of BAK Battery as an example, after 1000 cycles of charge and discharge, the battery capacity can still be maintained above 90% of the original. Since the author himself is also an electric vehicle owner, it is only during the coldest month of winter in the whole year. When the warm air is frequently turned on, the charging can be achieved every 2 days, and the rest is basically 3-4 days. Assuming an average charge for 3 days throughout the year, it will take about 6 times to charge in a year, and it will take about 8 years to complete the cycle life of 1,000 times. This basically exceeds the current average replacement cycle of Chinese consumers. 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