Are lithium iron phosphate battery packs and ternary lithium batteries safe?

The safety of the lithium iron phosphate battery pack depends critically on the basic electrochemical system and the internal factors such as the structure, design and processing technology of the electrode/cell, and the electrochemical system used by the cell is the most fundamental factor in determining the safety of the battery. factor. Needle stick, short circuit, squeeze When the lithium battery pack has a short circuit, needle stick or squeeze, it will cause the internal diaphragm to break and cause a sudden explosion in temperature, and eventually an explosion, especially for lithium batteries with poor safety performance. , This time will be even shorter, generally it will explode in about 5 seconds. Thermal shock The so-called thermal shock is the phenomenon of a sudden increase in the ambient temperature. If the temperature is high, it will cause analysis of the SEI film on the negative electrode surface of the lithium battery pack, which will trigger an exothermic reaction. If the battery heat dissipation is not good, the internal temperature will be It rises rapidly, resulting in a deflagration phenomenon. Overcharge If the lithium battery is overcharged, the excess electric energy will be converted into heat energy, which will cause damage to the temperature of the battery body. This problem often occurs in some current chargers or electronic products that do not have overcharge protection. Compared with the early lithium manganese battery, the energy density of lithium iron phosphate battery pack is not much different, about 100-110Wh/kg, but its thermal stability is the best among the current lithium batteries for vehicles. When the battery temperature is at a high temperature of 500-600℃, its internal chemical composition will begin to be analyzed. However, the lithium cobalt oxide battery, which is also a lithium battery, has an unstable internal chemical composition at 180-250℃. In other words, the safety of lithium iron phosphate batteries is second to none in lithium batteries, and because of this, it has also become one of the most important categories of electric vehicle batteries. It is difficult for lithium iron phosphate battery packs to undergo violent oxidation-reduction reactions during high-rate discharge, even during overcharge and discharge. At the same time, after lithium is deintercalated, the crystal lattice change will reduce the final volume of the unit cell (the smallest constituent unit of the crystal), which just offsets the added volume of the carbon negative electrode in the reaction. Therefore, the lithium iron phosphate is charged and discharged. The battery can maintain the stability of the physical structure, eliminating the hidden danger of battery bursting due to increase in volume. Is the ternary lithium battery safe? In recent years, the new energy automobile industry has ushered in rapid development, especially the ternary lithium battery electric vehicles with higher driving range have developed more rapidly, but the frequent occurrence of electric vehicles spontaneously ignites and catches fire The phenomenon has aroused the public's great concern about its safety. The shortcomings of ternary lithium batteries also lead to new energy buses that use ternary lithium batteries. There is no way to enter the new energy vehicle catalog. The reason is safety. The thermal stability of ternary lithium battery is poor, and analysis occurs at high temperature of 250-300℃, and the chemical reaction of ternary lithium material is particularly strong. Once oxygen molecules are released, the electrolyte will burn rapidly under high temperature applications, and then deflagration will occur. . Therefore, we can see that in extreme collision accidents, Tesla and other electric vehicles still have a fire hazard. However, in order to suppress such accidents, manufacturers have also spent a lot of effort to add overcharge protection, overdischarge protection, overtemperature protection, and overcurrent protection to the battery management system and heat dissipation system to monitor the battery status in real time. Measures adopted to improve the safety of ternary lithium batteries. Ternary lithium materials are easy to pyrolyze, but it does not mean that ternary lithium batteries are safe; lithium iron phosphate materials are not easy to pyrolyze, but it does not mean that lithium iron phosphate batteries are safe. Regardless of the technical route, it will be affected by the excessively active nature of lithium. Therefore, the safety of the battery is a matter of the entire system rather than the material. Its handling is not as simple as replacing the cathode material. 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: How to design the internal structure of lithium batteries to be safe?