The invention discloses a carbon-coated pre-
magnesium silicon monoxide negative
electrode material and a preparation method thereof, the negative
electrode material comprises a
silicon core, a
silicon-
magnesium composite
porous layer and a carbon-coated layer, the silicon-
magnesium composite
porous layer comprises MgSiO3 and Mg2SiO4 with porous characteristics, and the
porosity is not less than 30%; the material shows a unique peak position and intensity relationship in an XRD
diffraction pattern, and Mg2SiO4 is used as a main phase. According to the preparation method, through
molten salt mediated low-temperature
solid-
phase reaction and addition of reducing gas during heat treatment,
energy consumption is greatly reduced, a generated Mg2SiO4
crystal structure is more stable than traditional MgSiO3, and a porous structure (
porosity is larger than 30%) formed through the cooperation reaction enables the material to maintain high capacity of 1621.49 mAh / g, meanwhile, the first efficiency is improved to 85.91%, and the cyclic
expansion rate is reduced by 40% or above.