▎ 摘　　要

NOVELTY - Porous silicon carbon cathode material comprises core-shell structure where core is carbon-silicon cathode material and inner core is distributed with porous gap; shell comprises two layers structure, where inner layer is conductive material layer and outer layer is carbon coating layer. USE - Porous silicon carbon cathode material used for lithium ion battery (claimed). ADVANTAGE - The porous silicon carbon cathode material enables to solves problem that traditional silicon-based cathode volume expansion caused by low cycle performance, where compact amorphous carbon coating has small specific surface area, first coulomb efficiency is as high as 86.1 %, reversible specific capacity is 1517.1 mAh/g, capacity is above 85 % after 50 times of circulation. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for: (1) a method for preparing porous silicon carbon cathode material, which involves: (a) providing nano-silicon raw material, and first carbon source for ball milling; mixing, providing heat treatment to obtain first precursor; (b) mixing first precursor with second carbon source, providing heat treatment to obtain second precursor; (c) mixing second precursor with third carbon source heat treatment to obtain porous silicon carbon cathode material; (2) a lithium ion battery, which comprises battery shell, electric core set in battery shell, electrolyte filled in battery shell, where electric core, which comprises positive pole piece, diaphragm, and negative pole piece arranged in turn; cathode pole piece, which comprises cathode current collector, and cathode material located on cathode current collector; cathode material, which comprises silicon-carbon composite material. DESCRIPTION OF DRAWING(S) - The drawing shows a cross-sectional SEM appearance of sample obtained in Example 1.