Carbon and MXene Dual Confinement and Dense Structural Engineering Toward Construct High Performance Micron‐SiO_x Anode for Li‐Ion Batteries

Abstract The intrinsic low conductivity, low tap density, and huge volume expansion during lithium storage severely restrict the practicality of micron‐silicon suboxide (m‐SiO_x). Here, a carbon and MXene dual confinement and dense structural engineering strategy is proposed to construct m‐SiO_x composites (m‐SiO_x@C/MXene) through in situ carbon coating and electrostatic self‐assembly process. This integrated structural achieves a conductivity of 157 S cm⁻¹ for m‐SiO_x@C/MXene, which is 7 and 2 orders of magnitude higher than m‐SiO_x (5.3 × 10⁻⁵ S cm⁻¹) and m‐SiO_x@C (2.9 S cm⁻¹), respectively. The tap density of m‐SiO_x@C/MXene reaches 1.35 g cm⁻³, significantly greater than that of m‐SiO_x (0.82 g cm⁻³) and m‐SiO_x@C (0.75 g cm⁻³). The 29% volume expansion of m‐SiO_x@C/MXene during lithium storage is much lower than the 228% and 162% of m‐SiO_x and m‐SiO_x@C. The synergistic effect of the above advantages enables m‐SiO_x@C/MXene to exhibit excellent rate performance and cycle stability. When assembled into a full cell with the LiFePO₄ (LFP) cathode, it features high capacity retention and energy density of 99.1% and 380 Wh kg⁻¹ after 100 cycles at 0.2 C. This work provides new reference for the stable structural design of m‐SiO_x or other materials with huge volume expansion during energy storage.