At present, there are two mainstream battery technology routes for new energy vehicles, lithium iron phosphate batteries and ternary lithium batteries. To this end, we take representative parameters for comparison.

1. Choose BYD for bus and Tesla for sedan. This is the difference in volume between the two. From the current technology point of view, the energy density of ternary lithium batteries is generally 200Wh/kg, and may reach 300Wh/kg in the future; while lithium iron phosphate batteries are currently basically hovering at 100~110Wh/kg, and individual ones can reach 130~150Wh /kg, but it is very difficult to break through 200Wh/kg. Therefore, ternary material power batteries can provide twice as much space as lithium iron phosphate, which is very important for cars with limited space. Tesla produces ternary lithium batteries, and BYD produces lithium iron phosphate batteries, so there is a saying that “BYD is chosen for passenger cars and Tesla is chosen for cars”.

2. Because of the high energy density, the weight is much smaller, the light weight and the small footprint determine that the ternary lithium battery new energy vehicle consumes less power, so it is faster and has a stronger endurance. Therefore, cars can run farther with ternary lithium batteries, while lithium iron phosphate new energy vehicles are basically used for city buses at present, because they have a short battery life and need to be charged with a charging pile within a short distance.

3. Of course, the core of using lithium iron phosphate batteries in passenger buses is based on safety considerations. There are more than one fire accidents in Tesla cars. The reason is: Tesla’s battery pack is composed of about 7,000 18650 ternary lithium batteries. If these units or the entire battery pack have an internal short circuit, they will generate open flames and encounter extremes. In the collision accident, a short circuit caused a fire. The lithium iron phosphate material will not burn when encountering a short circuit, and its high temperature resistance is much better than that of a ternary lithium battery.

4. Although the lithium iron phosphate battery is resistant to high temperatures, the ternary lithium battery has better low temperature resistance. It is the main technical route for manufacturing low-temperature lithium batteries. At minus 20 °C, the ternary lithium battery can release 70.14% of the capacity. Lithium iron phosphate batteries can only release 54.94% of the capacity, and because under low temperature conditions, the discharge platform of ternary lithium batteries is much higher than the voltage platform of lithium iron phosphate batteries and starts faster.

5. The charging efficiency is higher with ternary lithium battery. Lithium battery charging adopts current-limiting and voltage-limiting method, that is, constant current charging is performed in the first stage. At this time, the current is large and the efficiency is high. After the 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, to measure the charging efficiency of the two, the ratio of the constant current charging power to the total battery capacity is called the constant current ratio. The experimental data shows that there is little difference between the two when charging under 10C, but the distance above 10C will increase the distance. When charging at 20C, the constant current ratio of the ternary lithium battery is 52.75%, and the constant current ratio of the lithium iron phosphate battery is 10.08 %, the former is 5 times that of the latter.

6. In terms of cycle life, the lithium iron phosphate battery is better than the ternary lithium battery. The theoretical life of the ternary lithium battery is 2000 times, but basically, the capacity decays to 60% when it is cycled 1000 times; even the best brand in the industry Sla can only maintain 70% of the power after 3000 times, while the lithium iron phosphate