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

Abstract 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.