Monothetic and conductive network and mechanical stress releasing layer on micron-silicon anode enabling high-energy solid-state battery

Silicon has ultrahigh capacity, dendrite-free alloy lithiation mechanism and low cost and has been regarded as a promising anode candidate for solid-state battery. Owing to the low infiltration of solid-state electrolyte (SSE), not the unstable solid–electrolyte interphase (SEI), but the huge stress during lithiation- and delithiation-induced particle fracture and conductivity lost tend to be the main issues. In this study, starting with micron-Si, a novel monothetic carbon conductive framework and a MgO coating layer are designed, which serve as electron pathway across the whole electrode and stress releasing layer, respectively. In addition, the in situ reaction between Si and SSE helps to form a LiF-rich and mechanically stable SEI layer. As a result, the mechanical stability and charge transfer kinetics of the uniquely designed Si anode are significantly improved. Consequently, high initial Coulombic efficiency, high capacity and durable cycling stability can be achieved by applying the Si@MgO@C anode in SSB. For example, high specific capacity of 3224.6 mAh·g⁻¹ and long cycling durability of 200 cycles are achieved. This work provides a new concept for designing alloy-type anode that combines surface coating on particle and electrode structure design.