High-strength and high-modulus silicon monoxide for high-energy-density and fast-charging lithium-ion batteries

Silicon-based negative electrodes suffer from severe mechanical degradation due to repetitive volumetric fluctuations and the resulting stress during cycling. Prevailing mitigation strategies enhance only elastic deformation resistance (via increased Young’s modulus) while overlooking yield strength improvement—critical for suppressing plastic deformation and cyclic fatigue under high-rate conditions. Here, we fabricate high-strength, high-modulus silicon monoxide incorporating intraparticle domains of crystalline lithium fluoride. By exploiting the (inverse) Hall–Petch relationship and the rule of mixtures for composites, size engineering of crystalline lithium fluoride domains maximizes particle-level mechanical reinforcement. The particles are simultaneously encapsulated by ionically conductive amorphous lithium fluoride/electronically conductive fluorine-doped carbon sheaths. This me…