In-situ introduction of inorganic SiOx with higher average valence promising core-shell Si@C anodes toward advanced lithium-ion batteries

Abstract

Si, as the most promising anode with high theoretical capacity for next-generation lithium-ion batteries (LIBs), is hampered in commercial application by its poor electrical conductivity and significant volume expansion. Herein, the core-shell Si@SiO_x/C@C-Ar (SSC-A) or Si@SiO_x/C@C-H₂/Ar (SSC-H) composites are purposefully designed by in situ introduction of inorganic SiO_x in pure Ar or H₂/Ar atmosphere to realize a Si-based anode for LIBs. By introducing different atmospheres, the valence states of SiO_x are regulated. The inorganic transition layer formed by the combination of SiO_x with higher average valence and asphalt-derived carbon demonstrates better performance in both stabilizing the core-shell structure and inhibiting the agglomeration of Si particles. Given these advantages, the SSC-A electrode exhibits excellent electrochemical performance (1163 mAh g⁻¹ after 400 cycles at 1 A g⁻¹), and the commercial blended graphite-SSC-A electrode reaches a specific capacity of 442 mAh g⁻¹ with 74.8% capacity retention under the same conditions. Even the SSC-A electrode without Super P maintains an ultrahigh discharge specific capacity of 803 mAh g⁻¹ with 60.6% after cycling. Importantly, the full batteries based on SSC-A without Super P achieve a discharge specific capacity of 126 mAh g⁻¹ with 28.2% capacity decay after 200 cycles, demonstrating the superior commercial application potential.