Sandwich structure endows Na3V2(PO4)3 cathodes with superb sodium storage

Abstract

Na3V2(PO4)3 (NVP) is a promising cathode for high-energy density sodium-ion batteries, whereas its electrochemical performance is also degraded by its intrinsically inferior electronic conductivity and interfacial side reactions. Herein, Li+, Al3+, and Ti4+ ions were incorporated into the near-surface, and NVP particles were encapsulated by a solid Na+ superionic conductor electrolyte Li1.4Al0.4Ti1.6(PO4)3 (LATP) and carbon (C). Typically, the 0.2 wt. % LATP/C-modified NVP electrode delivers a high initial discharge capacity of 91.22 mA h g−1 and a remarkable rate performance of 56.5 mA h g−1 (20 C). Intensive explorations manifest that the significant improvement in the electrochemical performance of NVP/C could be attributed to the synergistic effects of Li+, Al3+, and Ti4+ doping and the characteristic NVP/LATP/C sandwich coating structure. The modification strategy established in this work synchronously enhanced the electronic conductivity and structural stability of NVP, and this study also provides insight into well-designed electrode microstructures in high-performance batteries.