Preparation of low-expansion high-performance Si-C composites based on porous advantage of detoxified and purified waste cathode graphite blocks

Waste graphitization cathode carbon blocks are a type of hazardous solid waste generated during the aluminum electrolysis process, and their proper disposal is a key step in the resource utilization of discarded graphite. This study utilizes the porous "defect advantage" of a cathode carbon block matrix to prepare silicon-doped and asphalt-coated detoxified and purified waste graphitization cathode carbon blocks for use as high-performance silicon/carbon composite anode materials. The results show that the uniformly silicon-doped silicon/carbon composite material features a unique amorphous carbon-encapsulated "locked silicon" structure, which effectively addresses issues such as cathode volume expansion, excessive growth of the solid electrolyte interphase (SEI) film, and poor electrical contact between active materials. Consequently, electrochemical performance is enhanced. After assembly in a half-cell, the PSCC/10%Si@C material exhibits optimal electrochemical stability, with an initial charging specific capacity of 508.8 mAh/g at 0.1 C and a capacity retention rate of 98.2% after 50 cycles. At a charge rate of 2.0 C, a specific capacity of 216.9 mAh/g is achieved. This technology provides a new pathway for the economical and high-value utilization of waste cathode carbon blocks and the development of low-cost, high-performance anode materials.