Comparison of ternary lithium battery and lithium iron phosphate battery

Currently on new energy cars, there are two mainstream battery technology route, lithium iron phosphate batteries and ternary lithium batteries, although the two batteries compete in many application areas, but competition in the field of new energy vehicles as the main line, because this is the nation's largest lithium battery application scenario, since to compete, must have the comparison, The comparison of the cost performance of the battery through the price of the car can be carried out, and from the performance of the comparison of three yuan lithium battery and lithium iron phosphate battery which is good, it is necessary to set conditions to obtain the actual parameters of the two kinds of batteries. According to the experiments of relevant laboratories, new energy vehicle manufacturers and power battery manufacturers, although each test inevitably has slight differences in specific parameters, the judgment of the advantages and disadvantages of the two kinds of batteries tends to be consistent. To this end, we take representative parameters for comparison.

1. Byd for passenger cars and Tesla for cars. This is the difference in volume. From the perspective of current technology, the energy density of ternary lithium battery is generally 200Wh/kg, and may reach 300Wh/kg in the future. And lithium iron phosphate battery is basically hovering at 100~110Wh/kg, individual can reach 130~150Wh/kg, but it is very difficult to break through 200Wh/kg. As a result, ternary power batteries can provide twice as much space as lithium iron phosphate, which is important in space-constrained cars. Tesla produces ternary lithium batteries, and BYD produces lithium iron phosphate batteries, so there is a saying that "BYD is the passenger car and Tesla is the car".

2. Also because of the high energy density, the weight is much smaller, light weight and small space occupation determine that the ternary lithium battery new energy vehicle consumes less power, so the speed is faster and the endurance capacity is stronger. Therefore, cars can run farther with ternary lithium batteries, while lithium iron phosphate new energy vehicles are still basically used for city buses at present, because a range is not far, and there is a charging pile to charge in a short distance.

3. Of course, the use of lithium iron phosphate batteries in passenger buses is more fundamentally based on safety considerations. The reason is that Tesla's battery pack is composed of about 7,000 18650 ternary lithium batteries. If there is an internal short circuit in the battery or the whole battery pack of these units, open flame will be generated. In extreme collision accidents, short circuit will cause fire. The material of lithium iron phosphate will not burn when encountering short circuit, and the high temperature resistance is much superior to the ternary lithium battery.

4. Although lithium iron phosphate battery is resistant to high temperature, ternary lithium battery has better resistance to low temperature, which is the main technical route for manufacturing low-temperature lithium battery. At -20 °C, ternary lithium battery can release 70.14% of its capacity, while lithium iron phosphate battery can only release 54.94% of its capacity. The discharge platform of ternary lithium battery is much higher than that of lithium iron phosphate battery and the voltage platform starts faster.

5. Charging efficiency, ternary lithium battery is higher. Lithium battery is charged by current and voltage limiting method, that is, in the first stage of constant current charging, the current is large and the efficiency is high. When 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 charging power to the total battery capacity is used to measure the charging efficiency of the two, which is called constant current ratio. The experimental data show that there is little difference between the two charging conditions below 10C, but there will be a distance above 10C. When charging at 20C, the constant current ratio of ternary lithium battery is 52.75%, and that of lithium iron phosphate battery is 10.08%, the former is 5 times of the latter.

6. In terms of cycle life, lithium iron phosphate battery is better than teradic lithium battery. The theoretical life of teradic lithium battery is 2000 times, but the capacity decays to 60% when it reaches 1000 cycles. Even Tesla, the best brand in the industry, can only maintain 70 percent of its battery capacity after 3,000 cycles, while lithium iron phosphate batteries still have 80 percent capacity after the same cycle.