Multiple times mixed coating high compacted density silicon carbon negative electrode material and preparation method thereof

Abstract

The invention discloses a Multi-mixed and coated high compaction density silicon carbon anode material and a preparation method thereof, overcomes the defects that the surface of a silicon carbon material at the present is non-uniformly coated and is hardly intact, and solves the problem that the compaction density of a silicon carbon anode is hard to increase by means of a simple method. The silicon carbon anode material comprises primary particles and secondary particles, wherein the primary particles are porous silicon carbon materials; porous silicon is uniformly dispersed in activated carbon, and the surfaces of the porous silicon and the activated carbon are coated with a pyrolytic carbon coating layer having a thickness of 3 to 50 nm; the porous silicon accounts for 5 to 50 percentby mass of the primary particles, and the activated carbon accounts for 20 to 30 percent by mass of the primary particles; the pyrolytic carbon accounts for 20 to 75 percent by mass of the primary particles; the secondary particles are agglomerates formed by uniformly dispersing the primary particles and graphite in the pyrolytic carbon, and have a particle size of 5 to 100 [mu]m; the total carboncontent of the silicon carbon anode material is 80 to 90 percent; and the compaction density is 1.1 to 1.7 g / cm<3>.

Description

technical field

[0001] The invention relates to the field of lithium ion batteries, in particular to a preparation method for preparing high-density silicon-carbon negative electrode materials by mixing and coating multiple times. Background technique

[0002] With the rapid development of the field of electric vehicles, people have higher and higher requirements on the mass capacity density of power batteries. At present, most commercial lithium-ion secondary batteries use graphite as the negative electrode material. Due to the low theoretical capacity of graphite negative electrode, which is only 372mAh / g, the specific capacity of commercial graphite-based negative electrode materials is generally 300-360mAh / g. The improvement has been difficult to greatly improve the capacity density of the battery. Therefore, the development of anode materials for batteries with high specific capacity has become an urgent requirement of the lithium battery industry.

[0003] Among many...

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