Ternary lithium-ion batteries and lithium iron phosphate batteries

Power batteries include lithium-ion power batteries, metal hydride/nickel power batteries, etc. Lithium-ion power batteries are usually referred to as lithium-ion batteries. Lithium-ion batteries are an important category of power lithium batteries for new energy vehicles and have the largest market share.

Lithium iron phosphate battery: long cycle life and good safety

Lithium-ion batteries use lithium iron phosphate as the cathode material. Its characteristics are that it does not contain precious elements such as cobalt, the price of raw materials is low, and the content of phosphorus and iron is very rich. The LFP battery has moderate operating voltage (3.2V), large capacity per unit weight (170mAh/g), high discharge power, fast charging, long cycle life, and high stability in high temperature and high thermal environments.

1. High safety, high rate charge and discharge characteristics and long cycle life. According to the literature, charge it to 3.65V at 1C rate, then switch to constant voltage until the current drops to 0.02C, and then discharge at 1C rate to the cut-off voltage of 2.0V, after 1600 cycles, the battery capacity is still 80% of the initial capacity .

2. It has good fast charging characteristics. Under the condition of charging at 3C rate , the LFP battery can be charged to 55% in 15 minutes, and reach more than 95% of the capacity in 30 minutes.

3. The biggest advantage of LFP battery is its good safety. The chemical properties of LFP are stable, and the high temperature stability is good. It will start to decompose at 700-800 °C, and it will not release oxygen molecules in the face of impact, acupuncture, short circuit, etc., and will not cause violent combustion.

 4. The disadvantage is that its performance is greatly affected by temperature. Especially in the low temperature environment, the discharge capacity and capacity will be greatly reduced. The energy density is low, only 120Wh/kg.

Ternary lithium-ion battery: low temperature resistance and high energy density

The ternary lithium-ion battery is ternary polymer lithium-ion battery, and the positive electrode material uses ternary positive electrode material of nickel cobalt lithium manganate, that is, transition metal intercalated lithium oxide containing three elements of nickel, cobalt and manganese. This material combines the advantages of lithium cobaltate, lithium nickelate and lithium manganate to form a three-phase eutectic system of three materials. Due to the ternary synergistic effect, its comprehensive performance is better than that of any single combination compound. The gravimetric energy density can reach 200Wh/kg.

1. The voltage platform of the ternary lithium-ion battery is very high. Under the same volume or weight, the specific energy and specific power of the ternary lithium-ion battery are greater. In addition, ternary lithium-ion batteries have great advantages in terms of high rate charging and low temperature resistance.

2. The safety of ternary lithium-ion batteries is relatively poor. The thermal stability is poor, and it will decompose at 250-300 ℃. After encountering the flammable electrolyte and carbon material in the battery, it will be destroyed at a point. The heat that appears will further aggravate the decomposition of the positive electrode, and it will detonate in a very short period of time.

LiFePO4 battery is better

aterial prices, high safety and long service life have obvious advantages. Many battery manufacturers are also confident in the larger scale market of lithium iron phosphate. The analysis pointed out that after the real marketization, the advantages of low cost, long life and high safety of lithium iron phosphate will gradually appear in the fields of passenger cars, commercial vehicles and special vehicles.