How to improve the high temperature operating performance of lithium batteries

1) Improvement of materials made from lithium batteries In view of the poor cycle performance of lithium batteries at high temperatures, the positive electrode material can be modified to improve its high temperature cycle performance. At present, the modification of positive electrode materials requires bulk doping and surface Modification etc. Bulk doping includes cation doping, anion doping, composite doping and so on. Cation doping is critical for lithium manganate materials. After being doped with low-valent cations, Mn is partially replaced in the crystal, which increases the uniform valence and reduces the lattice constant, thereby reducing the dissolution of manganese; another On the one hand, the bond strength between the substituted cation and oxygen is higher than the bond strength between manganese ion and oxygen, which makes the structure more stable and inhibits the occurrence of the Jahn-Teller effect. Commonly used doping cationic elements are Al, Mg, Fe, Ni and so on. Anion doping mainly includes F, Cr, s2*, etc., and these electronegative anions are used to partially replace oxygen ions, thereby improving the stability of the material. Composite doping is doping with a variety of cations and anions [21-]. The bulk doping method can improve the cycle performance of the battery to a certain extent, but it will cause the decrease of the initial capacity of the lithium battery. At present, the most ideal doping method has not been found. The method of surface modification can reduce the direct contact between the material and the electrolyte and reduce the specific surface area of u200bu200bthe material, thereby reducing the dissolution of metal ions. The more commonly used method is to coat materials with metal oxides, metal fluorides, and more stable cathode materials. In addition to the modification of the positive electrode material, the surface of the graphite negative electrode is also coated to reduce the deposition of metal ions in the electrolyte on the surface of the negative electrode. (2) Improvement from the electrolyte of lithium batteries. The improvement of the electrolyte of lithium batteries is to improve its cycle performance by changing conductive salts and using electrolyte additives. The main reason for the dissolution of the positive electrode material of the battery is the presence of HF in the electrolyte, so reducing the occurrence of HF can reduce the dissolution of the positive electrode material. The LiBOB lithium salt can be used to guard against the emergence of HF and reduce the dissolution of metallic iron, thereby improving the high-temperature cycle performance of the lithium iron phosphate battery. The use of LiC104 conductive salt and the mixed conductive salt of LiBF4 and LiBOB improves the high temperature cycle performance of lithium iron phosphate batteries. In addition, water removal additives such as organic silicon such as silane can be used to reduce the generation of HF. In addition to guarding against the dissolution of positive metal ions, it is also necessary to reduce the deposition of metal ions in the electrolyte on the graphite surface. The most researched method is the use of additives. There are two ways for additives to inhibit the deposition of metal ions on the graphite surface. One is to form a dense passivation film on the surface of the negative electrode, which prevents the metal ions from contacting the graphite electrode, thereby reducing To prevent the deposition of metal ions; the other is to restrain the deposition of metal ions by trapping the metal ions in the electrolyte. (3) The new binder binder is an important part of the lithium battery pole piece, which has a significant impact on the performance of the battery. The performance of using CMC binder pole piece, compared with PVDF binder, the lithium battery using CMC binder shows better cycle performance and rate performance. 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: What factors are related to the service life of lead-acid batteries?