What are the fundamental requirements for electrolyte for lithium-ion batteries?

The electrolyte has a relatively large impact on the charging and discharging performance (rate bumpy temperature), life (recurrent storage), and temperature compatibility of lithium-ion batteries. Electrolytes used in lithium-ion batteries should generally meet the following fundamental requirements: a. High ion conductivity, generally should reach 1×10-3~2×10-2S/cm; b. High thermal and chemical invariance , Does not produce unfamiliar dispersion in a wider voltage range; c. A wider electrochemical window keeps the electrochemical function unchanged in a wider voltage range; d. Similar to other parts of the battery such as electrode materials and electrode current collectors It has excellent compatibility with barriers, etc.; e. Serene, non-toxic, and non-polluting. Important classification of electrolyte additives (1) Film-forming additives: VC has been widely used in competitions, and its important mechanism is that the appearance of the carbon negative electrode produces a free radical polymerization reaction to generate polyalkyl lithium carbonate compounds, thereby effectively inhibiting the co-embedding of solvent molecules; The important mechanism of PS, ES, DES, DMS and other substances is the reduction analysis. The important components for forming the SEI film are the inorganic salt Li2S, Li2SO3 or Li2SO4 and the organic salt ROSO2Li, which greatly enhance the invariance of the SEI film; (2) Security additives: Flame retardant additives, which reduce the heat release value and self-heating rate of the electrolyte, are importantly organic compounds containing P or F, such as organic phosphates, organic fluorides, and fluoroalkyl phosphates. The important mechanism of overcharging additives is redox shuttle reverberation (ferrocene) and electropolymerization reverberation (biphenyl, cyclohexylbenzene); (3) Multi-product additives: water removal, electrical conductivity, film formation and other comprehensive applications, Amide additives, which form hydrogen bonds with water, and contain lone pairs of electrons at the same time, which serve as a constant SEI film. (4) Overcharge protection additives: People have conducted extensive research on the methods of recycling redox pairs for internal protection. The principle of this method is that by adding a corresponding redox pair in the electrolyte, the redox pair is normally charged. No chemical or electrochemical reverberation is involved, and when the battery is fully charged or slightly higher than this value, the additives begin to oxidize on the positive electrode, and then diffuse to the negative electrode to produce a reducing reverberation. 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 is the difference in the material of the lithium-ion battery shell?