Lithium-ion battery safety testing indicators and safety solutions introduction

After the lithium-ion battery is produced, before it reaches the consumer, a series of tests must be carried out to ensure the safety of the battery as much as possible and reduce potential safety hazards. 1. Squeeze test: Put the fully charged battery on a flat surface, apply a pressure of 13±1KN by a hydraulic cylinder, and squeeze the battery from the flat surface of a steel rod with a diameter of 32mm. Once the squeeze pressure reaches the maximum stop Squeeze, the battery does not catch fire, just don't explode. 2. Impact test: After the battery is fully charged, place it on a flat surface, place a steel column with a diameter of 15.8mm vertically in the center of the battery, and drop a 9.1kg weight freely from a height of 610mm onto the steel column above the battery. The battery does not catch fire or explode. 3. Overcharge test: Fully charge the battery with 1C, and perform an overcharge test according to 3C overcharge 10V. When the battery is overcharged, the voltage rises to a certain voltage and stabilizes for a period of time. The battery voltage rises rapidly when it is close to the time. When it reaches a certain limit, the top cap of the battery is pulled off, the voltage drops to 0V, and the battery does not catch fire or explode. 4. Short-circuit test: After the battery is fully charged, the positive and negative electrodes of the battery are short-circuited with a wire with a resistance of no more than 50m, and the surface temperature of the battery is tested. The maximum temperature of the battery surface is 140°C. The battery cap is opened, and the battery does not catch fire or explode. . 5. Acupuncture test: Place the fully charged battery on a flat surface, and pierce the battery in the radial direction with a steel needle with a diameter of 3mm. The test battery does not fire or explode. 6. Temperature cycle test: The temperature cycle test of lithium ion battery is used to simulate the safety of lithium ion battery when it is repeatedly exposed to low temperature and high temperature environment during transportation or storage. The test is to use rapid and extreme temperature Changes are made. After the test, the sample should not fire, explode, or leak. Lithium-ion battery safety solutions address the many hidden safety hazards of lithium-ion batteries in the material, manufacturing and use process. How to improve the parts that are prone to safety problems is a problem for lithium-ion battery manufacturers to solve. 1Improving the safety of the electrolyte There is a high reaction activity between the electrolyte and the positive and negative electrodes, especially at high temperatures. In order to improve the safety of the battery, improving the safety of the electrolyte is one of the more effective methods. The potential safety hazards of electrolyte can be effectively solved by adding functional additives, using new lithium salts and using new solvents. According to the different functions of additives, the important ones can be divided into the following categories: safety protection additives, film forming additives, positive electrode protection additives, stabilizing lithium salt additives, lithium precipitation promoting additives, current collector anticorrosive additives, and wettability enhancing additives. In order to improve the performance of commercial lithium salts, researchers have substituted atoms on them and obtained many derivatives. Among them, compounds obtained by substituting atoms with perfluoroalkyl groups have many advantages such as high flash point, similar conductivity, and enhanced water resistance. , Is a kind of lithium salt compound with great application prospects. In addition, the anionic lithium salt obtained by chelating the boron atom with the oxygen ligand has high thermal stability. Regarding solvents, many researchers have proposed a series of new organic solvents, such as carboxylic acid esters and organic ethers. In addition, ionic liquids also have a class of electrolytes with high safety, but relatively commonly used carbonate-based electrolytes. The viscosity of ionic liquids is orders of magnitude higher, and the conductivity and ion self-diffusion coefficient are low. There is still a lot of work before practicality. To do. 2Improving the safety of electrode materials Lithium iron phosphate and ternary composite materials are considered to be low-cost, high-safety cathode materials, and may be popularized in the electric vehicle industry. Regarding the positive electrode material, the common method to improve its safety is coating modification. For example, the surface coating of the positive electrode material with a metal oxide can prevent the direct contact between the positive electrode material and the electrolyte, inhibit the phase change of the positive electrode material, and improve Its structural stability reduces the disorder of cations in the crystal lattice to reduce heat generation by side reactions. Regarding the negative electrode material, since the surface of the lithium ion battery is often the most prone to thermochemical decomposition and heat generation, improving the thermal stability of the SEI film is a key method to improve the safety of the negative electrode material. Through weak oxidation, metal and metal oxide deposition, polymer or carbon coating, the thermal stability of the negative electrode material can be improved. 3 Improve battery safety protection design. In addition to improving the safety of battery materials, commercial lithium-ion batteries adopt many safety protection measures, such as setting battery safety valves, thermal fuses, connecting components with positive temperature coefficients in series, using thermally sealed diaphragms, and loading Dedicated protection circuits, dedicated battery management systems, etc. are also means to enhance safety. Disclaimer: Some pictures and content of the articles published on this site are from the Internet. If there is any infringement, please contact to delete it. Previous: Why is the removable battery mobile phone no longer used?