Analysis of the advantages and disadvantages of lithium iron phosphate batteries and ternary lithium batteries

Lithium iron phosphate battery: a lithium battery with long cycle life and good safety. Lithium iron phosphate is used as a positive electrode material. Its characteristics are that it does not contain precious elements such as cobalt, the price of raw materials is low, and the resource content of phosphorus and iron is abundant. Its working voltage is moderate (3.2V), large capacity per unit weight (170mAh/g), high discharge power, fast charging and long cycle life, and high stability in high temperature and high heat environment. ① Lithium iron phosphate batteries are characterized by high safety, high rate charge and discharge characteristics and long cycle life. The literature shows that under the charging condition of 1C rate charging to 3.65V, then switching to constant voltage until the current drops to 0.02C, and then discharging to the cut-off voltage of 2.0V at 1C rate, the battery capacity still has 80% of the initial capacity after 1600 cycles. ②Lithium iron phosphate battery has good fast charging characteristics. Under the condition of 3C rate charging, it can be charged 55% in 15 minutes, and the capacity is more than 95% in 30 minutes. ③In addition to long life and excellent charge and discharge performance, the biggest advantage of lithium iron phosphate batteries is its safety. The chemical properties of lithium iron phosphate are stable and the high temperature stability is good. In the face of impacts, needle sticks, short circuits, etc., no oxygen molecules are released, no violent combustion occurs, and the safety performance is high. ④The disadvantage of lithium iron phosphate battery is that its performance is greatly affected by temperature, especially in low temperature environment, the discharge capacity and capacity will be greatly reduced. In addition, the energy density of lithium iron phosphate is relatively low, and the weight energy density of the battery is only 120Wh/kg. Ternary lithium battery: a ternary lithium battery with high temperature resistance and high energy density, that is, a ternary polymer lithium battery. The positive electrode material uses a lithium battery with nickel cobalt manganate ternary positive electrode material, that is, a transition containing three elements of nickel, cobalt and manganese. The metal intercalation lithium oxide conforms to the material of the positive electrode of the lithium battery. This material combines the advantages of lithium cobalt oxide, lithium nickel oxide 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 any single combination compound. The weight energy density can reach 200Wh/kg. ①Unlike lithium iron phosphate, the ternary lithium battery has a high voltage platform, which means that under the same volume or weight, the specific energy and specific power of the ternary lithium battery are greater. In addition, ternary lithium batteries have great advantages in terms of high-rate charging and low-temperature resistance. The temperature range in the northern winter is more suitable for ternary lithium batteries with better low-temperature performance, while lithium iron phosphate batteries that emphasize high-temperature performance will appear a little weak in the northern winter. ②The safety of ternary lithium battery is relatively poor. The thermal stability of ternary lithium battery is poor, and analysis will occur at 250-300℃. It will stop after encountering the combustible electrolyte and carbon materials in the battery. The heat that appears will further aggravate the positive electrode analysis, and the analysis will occur in a very short time. Will deflagrate. In a car accident, the impact of external force will damage the battery diaphragm and cause a short circuit. The heat emitted during the short circuit will cause the battery to run out of thermal control and quickly increase the temperature to above 300°C, posing a risk of spontaneous combustion. Therefore, for the ternary lithium battery, its battery management system and heat dissipation system are crucial. In order to improve the safety of the product, materials with strong heat resistance are used, a pressure relief valve is used to control the pressure in the battery, actively control the current of the battery, and monitor the battery charging status in real time, which can forcibly cut off the current loop to improve safety. These are all feasible measures to improve the safety of ternary lithium batteries. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous: Will the low-temperature discharge of lithium battery packs accelerate aging?