Lithium battery, silicon composite material for same and method for preparing silicon composite material

Abstract

The invention relates to a lithium battery, a silicon composite material for the same and a method for preparing the silicon composite material, and belongs to the technical field of lithium batteries. The silicon composite material for the lithium battery is provided with core-shell structures. Silicon particles are used as cores, shells comprise middle layers and outer layers, the middle layersare coated on the surfaces of the silicon particles, the outer layers are coated on the surfaces of the middle layers, the middle layers comprise non-electronic conductive high-polymer materials, theouter layers comprise inorganic lithium compounds, and the inorganic lithium compounds are a type of LiBH4, Li3N, Li2NH, LiBNH6 and Li1.8N0.4Cl0.6; a thickness ratio of the middle layers to the outerlayers is 1-5:1-5. The lithium battery, the silicon composite material and the method have the advantages that the non-electronic conductive high-polymer materials and the inorganic lithium compoundsare coated on the surfaces of the particles made of silicon materials, the quantities of lithium ions can be increased by the inorganic lithium compounds coated on the surfaces of the particles made of the silicon materials in charge and discharge procedures, and accordingly the first efficiency, the specific capacity and the cycle performances can be improved.

Description

technical field [0001] The invention relates to a silicon composite material for lithium batteries, a preparation method thereof and a lithium battery, belonging to the technical field of lithium batteries. Background technique [0002] With the rapid development of various lithium battery application markets, the market's requirements for the energy density of lithium-ion batteries continue to increase. At the same time, higher requirements are also placed on the specific capacity and cycle life of positive and negative electrode materials used in lithium-ion batteries. The current marketed graphite materials are difficult to meet the market demand due to their low specific capacity, while silicon carbon anode materials have the advantages of large specific capacity, wide range of material sources and simple preparation process. However, the current silicon-carbon anode material has a high expansion rate, which easily leads to a low cycle life of the battery, which seriousl...

AI Technical Summary

Problems solved by technology

This kind of material has self-agglomeration of silicon oxide and silicon particles, which easily leads to limited performance improvement. At the same time, although the electronic performance of the carbon material coated on the surface of the material is improved, the improvement of the lithium ion conductivity is very limited. The discharge efficiency is low, and the cycle performance of lithium batteries made of this material is poor

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