Mitigating Chemomechanical Degradation in All-Solid-State Batteries via Combined Porous Silicon and Hard-Carbon Architectures.

Silicon (Si) is a highly promising anode for next-generation all-solid-state batteries (ASSBs) owing to its exceptional theoretical capacity and low propensity for dendrite formation. However, severe volume fluctuations during (de)lithiation induce chemomechanical degradation and progressive loss of solid-solid contact, drastically limiting long-term cycling stability. Here, we report a structurally engineered anode comprising a porous silicon core conformally encapsulated by a graphene-like hard-carbon (HC) layer (pSi@C) to resolve these interfacial bottlenecks. The predefined internal voids of the porous framework intrinsically buffer Si swelling, while the robust carbon shell mitigates macroscopic mechanical stress and establishes a highly efficient mixed ionic-electronic transport network. Utilizing in situ three-electrode electrochemical impedance spectroscopy, we successfully decouple the interfacial kinetics, revealing significantly suppressed interfacial resistance during operation. Consequently, paired with an NCM811 cathode in a full-cell configuration, the pSi@C anode demonstrates robust cycling, delivering a capacity retention of 73.2% after 200 cycles at 0.5 C. This combined architectural design fundamentally addresses the chemomechanical failure of Si, offering a compelling pathway for the practical deployment of high-energy-density ASSBs.