2D VOPO4 Pseudocapacitive Ultrafast-Charging Cathode with Multi-Electron Chemistry for High-Energy and High-Power Solid-State Lithium Metal Batteries

Lithium metal batteries (LMBs) are acknowledged to be one major direction for next-generation energy storage devices. However, the practical applications of LMBs are certainly limited by the low power density and safety issues owing to the lack of high-capacity pseudocapacitive cathode materials and solid electrolytes. Herein, the rational synthesis of 2D VOPO4 nanosheets with enriched V4+ defects (VOPO4@G-Air) enabling ultrafast multi-electron reactions as a high-capacity pseudocapacitive cathode is reported. Through V4+ defect engineering, the larger polarizationand inhomogeneous multi-electron reactions are vastly improved, resulting in remarkably fast kinetics. Benefiting from the ultrathin 2D structure and controllably regulated V4+ defect concentration, a high discharge capacity of 313 mA h g(-1)at 0.1C is achieved, anda large capacity of 116 mA h g(-1) is offered at 50C. Finally, utilizing the as-synthesized VOPO4@G-Air and a solid-state electrolyte based on ethoxylated trimethylolpropane triacrylate (ETPTA-LiClO4-SSE) , the assembled solid-state LMBs (Li||ETPTA-LiClO4-SSE||VOPO4) show high energy density of 85.4 Wh kg(-1) at 114.5 W kg(-1) and high power density of 2.3 kW kg(-1) at 45.86 Wh kg(-1). Further, the pouch cell unveils extraordinary safety and excellent flexibility. This work provides new insights in the construction of ultrafast and high-capacity pseudocapacitive cathodes with multi-electron reactions for solid-state LMBs.