Method for preparing carbon-coated porous silicon-based lithium battery negative electrode material from photovoltaic crystalline silicon waste

The invention relates to a photovoltaic crystalline silicon waste treatment technology, in particular to a method for preparing a carbon-coated porous silicon-based lithium battery negative electrode material from photovoltaic crystalline silicon waste, which comprises the following steps: 1) reducing the size of the photovoltaic crystalline silicon waste to submicron level; 2) dissolving the treated photovoltaic crystalline silicon waste in a CH3CH2OH solution of NaOH, filtering, washing, drying, sintering and oxidizing the product, and finally etching with the NaOH solution at normal temperature to obtain porous silicon particles; 3) mixing the obtained porous silicon particles and CaCO3 into deionized water, performing ultrasonic dispersion to obtain a self-assembled porous silicon-CaCO3 particle precursor, performing centrifugal washing to complete solid-liquid separation, and performing pyrolysis on citric acid serving as a carbon source and the precursor in inert gas to obtain the carbon-coated porous s