Silicon-containing high-energy-density lithium ion battery

Abstract

The invention relates to a silicon-containing lithium ion battery with high energy density. The lithium ion battery comprises a positive electrode, a silicon-containing negative electrode, a fluorine-containing electrolyte, a diaphragm, electrode lugs and a packaging material. The silicon-containing negative electrode takes a silicon-based material as a whole or a part of electrochemical active substances. The electrolyte contains lithium salt, a non-aqueous organic solvent capable of dissolving the lithium salt, an SEI film-forming additive and hydrofluoroether. The solubility of the lithiumsalt in the non-aqueous organic solvent capable of dissolving the lithium salt is higher than 2 mol / L. The solubility of the lithium salt in the hydrofluoroether is lower than 0.3 mol / L, wherein the non-aqueous organic solvent capable of dissolving the lithium salt is mutually dissolved with the hydrofluoroether, the non-aqueous organic solvent capable of dissolving the lithium salt and the liquidSEI film-forming additive are mutually dissolved, so the solid SEI film-forming additive can be dissolved. The silicon-containing lithium ion battery has the advantages of high energy density, long cycle life, good rate capability, high safety performance, difficulty in expansion and deformation and the like.

Description

technical field [0001] The invention relates to the field of lithium ion batteries, in particular to a silicon-containing lithium ion battery with high energy density. Background technique [0002] Due to the rapid development and wide application of various portable electronic devices, new energy electric vehicles, and energy storage systems in recent years, the demand for lithium-ion batteries with high energy density, long cycle life, safe use, and good rate characteristics has become increasingly urgent. [0003] At present, the negative electrode material of commercialized lithium-ion batteries is mainly graphite, but due to the low theoretical capacity (372mAh / g), the improvement of the energy density of lithium-ion batteries is limited. Silicon-based anode materials have the advantage of high capacity that other anode materials cannot match. In recent years, silicon-based anode materials have become a research and development hotspot, and have gradually moved from lab...

AI Technical Summary

Problems solved by technology

However, if the proportion of lithium salt in the electrolyte is too high, the viscosity of the electrolyte will be significantly increased, the activity of lithium ions will be reduced, and the mobility of lithium ions in the electrolyte will be significantly reduced. Wet, the result is that the actual capacity of the battery is low and the rate characteristics are poor.

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