Revealing stable organic cathode/solid electrolyte interface to promote all-solid-state sodium batteries using organic cathodes

All-solid-state sodium batteries (ASSBs) offer an attractive low-cost and high-safety power source for vehicles and stationary power plants beyond of lithium-based batteries. Currently, their application is limited by the rigid solid electrolyte (SE)/electrode contact interface which causes large interfacial resistance and poor cycling stability. Here we reveal a soft perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) as a representative organic cathode material shows good mechanical and electrochemical compatibility with a rigid inorganic Na₃Zr₂Si₂PO₁₂ SE, thus can promote the ASSBs using organic cathodes. Specifically, all-solid-state PTCDA/Na₃Zr₂Si₂PO₁₂/sodium batteries are assembled which show a smaller charge transfer resistance of 310 Ω cm² at 25 °C than that (460 Ω cm²) of the PTCDA//sodium batteries using a conventional liquid electrolyte. Moreover, the all-solid-state sodium battery delivers an initial capacity of 120.8 mAh g^-1, and achieves a retention of 73.4% over 500 cycles at 200 mA g^-1, while the liquid battery shows quick capacity decay after the 50th cycles. This work demonstrates an effective strategy by combining a soft cathode with a rigid solid electrolyte to overcome the interfacial issues of ASSBs, and will promote the development of ASSBs using diverse cathodes of low cost, high specific capacity, and long-term reliability.