which lithium ion battery is best?
At present, there are two mainstream battery technology routes in new energy vehicles, lithium iron phosphate battery and ternary lithium battery. Although these two batteries compete in many application fields, this is the largest lithium battery application scene in China. According to the experiments of related laboratories, new energy automobile manufacturers and power battery manufacturers, although there are nuances in specific parameters in each test, the judgment of the performance of the two batteries tends to be consistent. Therefore, we take representative parameters to compare.
1. passenger cars choose BYD, cars choose Tesla. This is the difference in volume between the two. Judging from the current technology, the energy density of ternary lithium batteries may reach 300 Wh/kg; in the future in 200 Wh/kg,, while lithium iron phosphate batteries are basically hovering around 100~110 Wh/kg, and individual batteries can reach 130 to 150, but it is very difficult to break through 200 Wh/kg. Therefore, ternary power batteries can provide twice as much space as lithium iron phosphate, which is important for cars with limited space. Tesla produces ternary lithium batteries, BYD produces lithium iron phosphate batteries, so there is a "bus to choose BYD, cars to choose Tesla" said.
2. also because of the large energy density, the weight is much smaller, the light weight and the small space occupation determine the ternary lithium battery new energy vehicle to consume less electricity, therefore the speed is faster, the endurance is stronger. Therefore, the car can run farther by using ternary lithium battery, and the new energy car of lithium iron phosphate is still basically used in the city bus at present, because it is not far away at a time and needs to have charging piles in a short distance to charge.
3. of course, passenger buses using lithium iron phosphate battery more core is based on safety considerations. Tesla car fire accident more than one, because: Tesla battery pack consists of about 7000 pieces of 18650 ternary lithium battery, these units of batteries or the entire battery pack if there is an internal short circuit will produce open fire, encounter extreme collision accident, short circuit causes fire. The material of lithium iron phosphate will not burn in short circuit, and the high temperature resistance is much better than that of ternary lithium battery.
4. lithium iron phosphate battery has better low temperature resistance, but ternary lithium battery is the main technical route to manufacture low temperature lithium battery. At minus 20°C, ternary lithium battery can release 70.14% capacity. Lithium iron phosphate battery can only release 5 4.94% capacity.
5. charging efficiency, ternary lithium battery is higher. Lithium battery charging is based on current limiting method, that is, constant current charging in the first stage. After constant current charging reaches a certain voltage, it enters the second stage of constant voltage charging. At this time, the current is small and the efficiency is low. Therefore, the ratio of constant current charge quantity to total battery capacity is called constant current ratio. The experimental data show that there is little difference between the two when charging below 10 C, but more than 10 C will open the distance. When charging at 20 C, the constant current ratio of ternary lithium battery is 52.75 and the constant current ratio of lithium iron phosphate battery is 10.08. The former is 5 times the latter.
6. the cycle life, lithium iron phosphate battery is better than ternary lithium battery, the theoretical life of ternary lithium battery is 2000 times, but basically to 1000 cycles, the capacity attenuates to 60. After 3000 times can only maintain 70% electricity, and lithium iron phosphate battery after the same cycle ,80% capacity.
The comparison of the above six aspects can be concluded that the relative advantages of the two are helpful to answer the good questions of ternary lithium battery and lithium iron phosphate battery: lithium iron phosphate battery is safe, long life and high temperature resistance; ternary lithium battery is light weight, high charging efficiency and low temperature resistance.
