Silicon-based negative electrode electrolyte and lithium ion power battery

Abstract

The invention discloses a silicon-based negative electrode electrolyte and a lithium ion power battery. The silicon-based negative electrode electrolyte comprises lithium salt, a fluorinated ether-containing organic solvent, a film-forming additive, a degassing additive and lithium nitrate, and is characterized in that the film-forming additive is lithium difluorophosphate and pentafluorophenyl isocyanate (PFPI). The lithium salt used in the electrolyte of the invention is mainly composed of high-conductivity lithium bisfluorosulfonimide, lithium hexafluorophosphate and lithium oxalyldifluoroborate; the three kinds of lithium salt are mixed to work under high voltage and temperature; the lithium oxalyldifluoroborate forms SEI films at both positive and negative electrodes, the battery still has good electrochemical performance even without adding other film-forming additives, and due to the existence of fluorinated ether and adiponitrile, the electrolyte has a certain antioxidant capacity; and due to the existence of the degassing additive, the gas production amount during cycle and high temperature storage processes of the battery can be reduced.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries, in particular to a silicon-based negative electrode electrolyte and a lithium ion power battery. Background technique [0002] With the gradual development of new energy vehicles, the energy density of current power batteries is difficult to meet the requirements of high battery life. In order to improve the energy density of power batteries, most power battery manufacturers are gradually using silicon-based negative electrode materials with a high theoretical gram capacity. Although the silicon-based anode has a high theoretical capacity, the SEI film on the surface of the anode is continuously broken and formed due to the large volume expansion of the silicon-based anode, so its cycle performance is poor. Therefore, it is particularly important to equip an electrolyte with good performance for batteries using silicon-based negative electrodes. At present, the main components of c...

AI Technical Summary

Problems solved by technology

[0003] At present, the lithium salt of silicon-based electrolyte is mainly lithium hexafluorophosphate, and the solvent is mainly carbonate solvent mixed with fluoroethylene carbonate solvent. This type of electrolyte tends to form SEI film continuously during the battery cycle, which makes the battery capacity decay quickly. , the internal resistance of the battery continues to increase, and fluoroethylene carbonate is prone to defluorination reaction at high temperature, producing hydrogen fluoride, which will produce more gas

Images