Single-Crystalline, Semiconductive Layered Organic Cathode Powers High-Energy All-Solid-State Batteries

All-solid-state batteries (ASSBs) offer a pathway to improved safety and increased energy density but remain limited by sluggish ion transport and low active material loading in composite cathodes. Organic cathode materials provide a sustainable alternative to metal-based systems, yet their implementation in solid-state architectures is constrained by poor electronic conductivity and inefficient electrode microstructures. Here, we integrate a high-capacity, semiconductive, single-crystalline layered organic cathode into ASSBs and demonstrate an electrochemical performance comparable to that of conventional systems. Systematic optimization of cathode composition identifies a configuration that delivers a specific capacity of 310 mAh g^-1 at 25 mA g^-1 with stable cycling over 100 cycles at room temperature under moderate pressure. At this rate, the architecture achieves an active-material-level energy density of 638 Wh kg^-1. Performance limitations are mitigated through compositing with single-walled carbon nanotubes and operation at an elevated temperature. Electrochemical impedance spectroscopy indicates simplified interfacial behavior and suppressed side reactions relative to conventional solid-state cathodes, while in situ measurements reveal volcano-shaped lithium-ion diffusion behavior arising from the interplay between structural evolution and site occupancy. These results define design constraints for organic solid-state cathodes and establish their viability as functional components in next-generation solid-state energy storage.