Catholyte-free cathode design for high-energy-density all-solid-state lithium batteries

All-solid-state lithium batteries (ASSLBs) are regarded as pivotal next-generation energy devices owing to their safety and high energy-density potential. Nevertheless, conventional cathodes, which rely on excessive inactive solid electrolyte (SE) fillers (20-40%), suffer from limited cathode active material (CAM) content, tortuous ion transport, and unstable CAM/SE heterogeneous interfaces, severely restricting the energy density and cycling durability of ASSLBs. As an emerging frontier design, catholyte-free cathode architectures fundamentally eliminate extrinsic SE components, enabling ultrahigh CAM utilization (>95%), low Li-ion transport tortuous, and suppressed interfacial side reactions and mechanical degradation. This review systematically summarizes the recent advances of catholyte-free ASSLBs, encompassing oxide, sulfide and halide catholyte-free cathode, and elaborates material optimization strategies such as defect modulation, amorphization engineering, and composite structural design. We further elucidate the intrinsic interfacial and chemo-mechanical merits of homogeneous CAM/CAM interface over heterogeneous CAM/SE interface, and outline future optimization guidelines to facilitate the development of high-energy-density ASSLBs.