What methods can improve the safety of batteries?

1. Use safe lithium battery electrolytes. At present, lithium battery electrolytes use carbonates as solvents. Among them, linear carbonates can improve the charge and discharge capacity and cycle life of the battery, but their flash points are low, which can be achieved at lower temperatures. Will flash, and fluorinated solvents usually have a higher flash point or even no flash point, so the use of fluorinated solvents is beneficial to inhibit the burning of the electrolyte. The fluorinated solvents currently studied include fluorinated esters and fluorinated ethers. Flame-retardant electrolyte is a functional electrolyte, and the flame-retardant function of this type of electrolyte is usually obtained by adding flame-retardant additives to conventional electrolytes. Flame-retardant electrolyte is currently the most economical and effective measure to solve the safety of lithium batteries, so it is especially valued by the industry. Using solid electrolytes instead of organic liquid electrolytes can effectively improve the safety of lithium batteries. Solid electrolytes include polymer solid electrolytes and inorganic solid electrolytes. Polymer electrolytes, especially gel polymer electrolytes, have made great progress. They have been successfully used in commercial lithium batteries, but gel polymer electrolytes are actually a compromise between dry polymer electrolytes and liquid electrolytes. As a result, its improvement in battery safety is very limited. Since the dry polymer electrolyte does not contain liquid flammable organic plasticizers like gel polymer electrolytes, it has better safety in terms of leakage, vapor pressure and combustion. The current dry-state polymer electrolytes still cannot meet the application requirements of polymer lithium batteries, and further research is still needed to be expected to be widely used in polymer lithium batteries. Relative to polymer electrolytes, inorganic solid electrolytes have better safety, are non-volatile, non-flammable, and will not have liquid leakage problems. In addition, the inorganic solid electrolyte has high mechanical strength, and the heat-resistant temperature is significantly higher than that of liquid electrolytes and organic polymers, which expands the operating temperature range of the battery; making inorganic materials into thin films makes it easier to achieve miniaturization of lithium batteries, and this type of battery has The long storage life can greatly broaden the application fields of existing lithium batteries. 2. Improve the thermal stability of electrode materials. The safety problem of lithium batteries is directly caused by unsafe electrolyte, but at the root, it is caused by the low stability of the battery itself and the occurrence of thermal runaway. In addition to the thermal stability of the electrolyte, the thermal stability of the electrode material is also one of the most important reasons for the occurrence of thermal runaway. Therefore, improving the thermal stability of the electrode material is also an important part of improving the safety of the battery, but the electrode mentioned here The thermal stability of a material includes not only its own thermal stability, but also its mutual use with electrolyte materials. Generally, the thermal stability of the negative electrode material is determined by its material structure and the activity of the charged negative electrode. Regarding carbon materials, spherical carbon materials, such as mesophase carbon microspheres (MCMB), are related to flake graphite, which have a lower specific surface area and a higher charge and discharge platform, so their charged state activity is relatively small, and their thermal stability is relatively high. Good, high security. The spinel structure of Li4Ti5O12 has better structural stability related to layered graphite, and its charge and discharge platform is also much higher, so it has better thermal stability and higher safety. Therefore, MCMB or Li4Ti5O12 is usually used instead of ordinary graphite as the negative electrode in power lithium-ion batteries with higher safety requirements. Generally, in addition to the material itself, the thermal stability of the negative electrode material, for the same material, especially graphite, the thermal stability of the solid electrolyte interface membrane (SEI) at the interface between the negative electrode and the electrolyte is more concerned, and this is usually It is considered the first step in the occurrence of thermal runaway. There are two important ways to improve the thermal stability of the SEI film: one is the surface coating of the negative electrode material, such as coating an amorphous carbon or metal layer on the graphite surface; the other is to add a film-forming additive to the electrolyte to add a film-forming additive to the battery During the activation process, they form a stable SEI film on the surface of the electrode material, which is conducive to obtaining better thermal stability. 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 article: What factors should be considered when choosing lithium battery cathode materials?