The Life Of Lithium Iron Phosphate Is Four Times Of NCM Lithium Battery, Why Do Electric Vehicles Still Use Ternary Lithium Batteries(NCM)?

Among the lithium battery packs of electric vehicles, the conventional ones are the lithium iron phosphate battery pack and the ternary lithium battery pack. The cycle life of lithium iron phosphate is about 2000~3000 times, and the cycle life of ternary lithium is about 500~800 times. From the perspective of cycle life, the life of lithium iron phosphate batteries is about 4 times that of ternary lithium. Why would a large part of electric vehicles use ternary lithium batteries?

Let’s share this today and compare the difference between lithium iron phosphate batteries and ternary lithium. 

1. Compared with cycle life, lithium iron phosphate has obvious advantages

The cycle life of the iron-lithium battery cell is about 2000~3000 times. After assembled into the PACK battery pack, the cycle life is about 1500~2000 times; the cycle life of the ternary lithium battery cell is about 500~800 times. After assembled into the PACK battery pack, The cycle life is about 300~500 times. (Test conditions: 1C charge and discharge, 25℃ laboratory environment, discharge depth DOD100%)

Whether it is a battery or a battery pack, the life of lithium iron phosphate will be much longer than that of ternary lithium.

2. Stability comparison, lithium iron phosphate is slightly better

Due to the characteristics of the material, the stability of lithium iron phosphate is slightly better than that of ternary lithium. Under some abnormal conditions, such as cell overcharge, high temperature, short circuit, etc., the stability of the ternary lithium material will be worse than that of lithium iron phosphate.

3. Compared with energy density, ternary lithium has obvious advantages

In terms of weight energy density, the weight energy density of ternary lithium can reach 300Wh/Kg, while the weight energy density of lithium iron phosphate is only about 150Wh/Kg.

In terms of volume energy density, the volume energy density of ternary lithium can reach 700Wh/Kg, while the volume energy density of lithium iron phosphate is only about 350Wh/L.

To give an example in practical application,

The standard Xiaoliying outer box can hold 288 18650 batteries.

If you use lithium iron phosphate battery 18650-3.2V-1600mAh, you can achieve 19 series 15 parallel, capacity 60.8V24Ah, 1459.2Wh.

If you use ternary lithium battery 18650-3.6V-3500mAh, you can achieve 17 series 16 parallel, capacity 61.2V56Ah, 3427.2Wh.

Compared with the watt-hour, the watt-hour of the ternary lithium battery pack will be about 2.3 times that of lithium iron phosphate under the same volume and weight. It can be said that in terms of energy density, ternary lithium is better than lithium iron phosphate.

Capacity watt-hours are closely related to the range of electric vehicles. This is why some electric vehicles have to choose to use ternary lithium batteries when they are particularly concerned about the range. Under the same capacity battery pack, ternary lithium is light and small, which meets the needs of many small and portable electric vehicles.

4. Cost comparison, ternary lithium is slightly affordable

In summary, if the electric vehicle products focus on the cycle life and safety of the lithium battery pack, the lithium iron phosphate battery is the first choice; if the focus is on the cruising range, the energy density of the lithium battery pack, and the price, the first choice It must be a ternary lithium battery. You can use a BMS with better performance to control the safety and stability of the lithium battery pack.

So, this is why a large part of electric vehicle batteries still use ternary lithium.