F.F. Xing, F. Su, J.Q. Qin, P.C. Wen, Y.J. Li, L.Z. Zhang, J.X. Ma, S.H. Zheng, X. Guo, Z.-S. Wu*

Advanced Energy Materials, 2023, 13.

DOI: 10.1002/aenm.202204015 [PDF]

Lithium metal batteries (LMBs) are acknowledged as one major direction for next-generation energy storage devices owing to the high-capacity and low potential of lithium anode. 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 with matchable solid electrolytes.Herein, we report the rationally synthesis of two-dimensional (2D) VOPO₄nanosheets with enriched V⁴⁺defects (VOPO₄@G-Air) enabling ultrafast multi-electron reactions as high-capacity and fast-charging pseudocapacitive cathode. Through V⁴⁺defect engineering, the larger polarization, complex and inhomogeneous multi-electron reactions when charging from 1.5 to 3 V are vastly improved, resulting in remarkably fast kinetics and enhanced high-rate capability. Benefiting from ultrathin 2D structure and controllably regulated V⁴⁺defect concentration, a high discharge capacity of 313 mA h g^-1with two electron transfer at 0.1 C is achieved, and even at an ultrafast rate of 50 C, a large capacity of 116 mA h g^-1is offered for VOPO₄@G-Air, far exceeding the reported VOPO₄. Finally, utilizing the as-synthesized VOPO₄@G-Air and a solid-stateelectrolytebasedonethoxylated trimethylolpropane triacrylate(ETPTA-LiClO₄-SSE)possessing robustroom-temperatureionic conductivity of 0.99 mS cm^-1, the assembled solid-state LMBs (Li||ETPTA-LiClO₄-SSE||VOPO₄) show high energy density of 85.4 Wh kg^-1at 114.5 W kg^-1and high power density of 2.3 kW kg^-1at 45.86 Wh kg^-1. Further, the pouch cell unveils extraordinary safety and excellent flexibility. Therefore, this work provides new insights on constructing ultrafast and high-capacity pseudocapacitive cathodes with multi-electron reactions for solid-state LMBs.