Mechanical Pressing Route for Scalable Preparation of Microstructured/Nanostrutured Si/Graphite Composite for Lithium Ion Battery Anodes

Si/graphite composite has been regarded as one of the promising anode materials for next-generation lithium ion batteries (LIBs). Herein, we reported a mechanical pressing route to fabricate Si-embedded/graphite composite on a large scale with increased tap density and decreased BET specific surface area. By mechanical pressing of well-dispersed Si and graphite particles, the Si nanoparticles are embedded into the graphite sheets and form ingot-shaped tablets. After secondary grinding, the aggregated Si/graphite (Si/G) microparticles are obtained with close integration of Si and graphite at the nanoscale. Finally, a layer of amorphous carbon was deposited on the above composite (Si/G/C microparticles) via decomposing acetylene to further maintain the structural stability of the Si/G/C microparticles. As a result, the as-obtained Si/G/C microparticles deliver a discharge capacity of 520.7 mA h g–1 at 0.2 C after 100 cycles and 370 mA h g–1 at 1 C after 800 cycles, associated with improved Coulombic efficiency. The full cell assembled with the Si/G/C microparticles as anode and commercial LiCoO2 as cathode can maintain a capacity retention of about 80% at 0.5 C after 50 cycles with a working potential beyond 3.1 V. The improved performance could be attributed to the enhanced structural stability and good integration of Si and graphite at the nanoscale after mechanical pressing.