Patent ID: 11929484
Assignee: BTR NEW MATERIAL GROUP CO., LTD.
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC H  C  Y | IPC C  H

Claim 5:
6. A preparation method of a composite, wherein the composite is a Si—O—C—Li composite comprising nano-silicon, a silicon-oxygen-lithium compound selected from the group consisting of Li2SiO3, Li4SiO4, Li2Si2O5, Li2Si3O7 and combinations thereof, silicon oxide and a carbon coating:
wherein the silicon-oxygen-lithium compound is partially crystalline, the nano-silicon is dispersed in the silicon-oxygen-lithium compound to form fusion particles of the nano-silicon and the silicon-oxygen-lithium compound without clear interface between the nano-silicon and the silicon-oxygen-lithium compound, and the fusion particles are uniformly dispersed in the silicon oxide to form a composite particle wherein all directions of the fusion particles are surrounded by the silicon oxide matrix, forming a sea-island structure with the fusion particles as islands and with the silicon oxide as the sea, with the carbon coating coated on the surface of the composite particles; and
wherein the nano-silicon and the silicon-oxygen-lithium compound are produced by in-situ redox growth;
the preparation method comprises the following steps:
(1) blending a carbon-coated silicon oxide and a lithium source by solid-phase mixing mode to implement primary treatment to form a pre-lithium precursor; wherein the lithium source undergoes a redox reaction with the silicon oxide in the interior of the carbon coating, and in-situ redox growth results in nano-silicon and a silicon-oxygen-lithium compound, and there is no clear interface between the nano-silicon and the silicon-oxygen- lithium compound; wherein the solid-phase mixing mode comprises any one selected from the group consisting of ball milling, VC mixing, fusion, mixing, kneading, dispersion, or a combination of at least two selected therefrom, and the solid-phase mixing mode is performed in vacuum condition;
(2) heat-treating the pre-lithium precursor in vacuum or a non-oxidizing atmosphere to implement structural adjustment and secondary treatment to form the Si—O—C—Li composite according to any of claim 1, wherein the lithium source infiltrates into the interior of the carbon-coated silicon oxide to react in situ with the silicon oxide to produce nano-silicon and the Si—O—C—Li composite, wherein the temperature of the heat-treating is 160-1000° C., and the time for the heat-treating is 2-12 h;
(3) subjecting the composite to surface treatment to compound the residual lithium or silicon-oxygen-lithium compound on the surface to the interior to obtain a surface- treated composite; the manner of compounding the residual lithium or the silicon-oxygen- lithium compound is any one selected from the group consisting of coating, cladding, film plating, spraying, and a combination of at least two selected therefrom; the manner of impurity removal is any one selected from the group consisting of washing, impregnation, and a combination of at least two selected therefrom, the washing or impregnation is carried out using an impurity removing solution.