The lithium iron phosphate battery refers to a lithium ion 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 the specific energy and specific power of the ternary lithium battery are greater under the same volume or weight. 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.
Regarding the battery 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.
As baterias de material ternário são mais adequadas para carros de passeio.
1. Tem um melhor desempenho de descarga de baixa-temperatura.
"Relative 25 degree capacity" refers to the ratio of the discharge capacity under different temperature conditions to the discharge capacity at 25 degree . This value can accurately reflect the attenuation of battery life under different temperature conditions. The closer to 100 percent , the better the battery performance.
As can be seen from the above figure, with 25 degree as the reference room temperature, the discharge capacity of the two types of batteries is almost the same when discharged at a high temperature of 55 degree and at a normal temperature of 25 degree . But at minus 20 degree , ternary lithium batteries have obvious advantages compared with lithium iron phosphate batteries.
2. Maior densidade de energia
According to the information provided by BAK Battery, the leading domestic ternary material 18650 cylindrical battery company, 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 not only solves the weight problem, but also saves space for family cars.
3. Higher charging efficiency
In addition to endurance, charging is also an important part of the actual use of electric vehicles, and ternary lithium batteries have a very large advantage over lithium iron phosphate batteries in terms of charging efficiency.
The more 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 phase, and it 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 significant 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.
4. Ciclo de vida garantido
The rated cycle life of the ternary material and the lithium iron phosphate power battery far exceeds the actual user's usage habits, so the service life can be completely assured.
Take 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 at more than 90 percent of the original.
5. Materiais e processos seguros
The most harmful part of traditional internal combustion engine vehicles is the fuel with huge energy. If liquid fuel with low ignition point and explosiveness like gasoline leaks, it is very easy to cause great safety hazards.
The power batteries of new energy vehicles are monitored by a complete battery management system (BMS), and each battery can be controlled most accurately to prevent accidents.
Bem-vindo ao inquérito: sales21@socmachinery.com
Editor: Sukie Shih
