Building K-C Anode with Ultrahigh Self-Diffusion Coefficient for Solid State Potassium Metal Batteries Operating at-20 to 120 degrees C

Solid state potassium (K) metal batteries are intriguing in grid-scale energy storage, benefiting from the low cost, safety, and high energy density. However, their practical applications are impeded by poor K/solid electrolyte (SE) interfacial contact and limited capacity caused by the low K self-diffusion coefficient, dendrite growth, and intrinsically low melting point/soft features of metallic K. Herein, a fused-modeling strategy using potassiophilic carbon allotropes molted with K is demonstrated that can enhance the electrochemical performance/stability of the system via promoting K diffusion kinetics (2.37 x 10(-8) cm(2) s(-1)), creating a low interfacial resistance (approximate to 1.3 omega cm(2)), suppressing dendrite growth, and maintaining mechanical/thermal stability at 200 degrees C. A homogeneous/stable K stripping/plating is consequently implemented with a high current density of 2.8 mA cm(-2) (at 25 degrees C) and a record-high areal capacity of 11.86 mAh cm(-2) (at 0.2 mA cm(-2)). The enhanced K diffusion kinetics contribute to sustaining intimate interfacial contact, stabilizing the stripping/plating at high current densities. Full cells coupling ultrathin K-C composite anodes (approximate to 50 mu m) with Prussian blue cathodes and beta/beta ''-Al2O3 SEs deliver a high energy density of 389 Wh kg(-1) with a retention of 94.4% after 150 cycles and fantastic performances at -20 to 120 degrees C.