Reducing atmosphere improves the conductivity of NaTi2(PO4)3/C material for hybrid aqueous rechargeable lithium-ion battery anode

Abstract

Hybrid aqueous rechargeable lithium-ion batteries (HARLIBs) have lower cost and better safety performance than conventional lithium-ion batteries (organic electrolytes). The challenge faced by HARLIBs are the narrow selection of anode and cathode materials, and overcoming the problems of capacity decay of anode and cathode materials in aqueous electrolytes. NaTi2(PO4)3, which has a stable three-dimensional open framework structure, shows certain applicability in HARLIBs, but its inherent low electronic conductivity leads to poor utilization of active materials and inferior rate performance. In this article, we propose an experimental method that can improve the conductivity of NaTi2(PO4)3/C, and study the electrochemical performance of NaTi2(PO4)3/C aqueous half-cell and NaTi2(PO4)3/C||LiMn2O4 hybrid aqueous full cell. The results show that Ti3+/oxygen vacancies can endow NaTi2(PO4)3/C with higher conductivity and improve the specific capacity and rate capability (69 mAh·g−1, 7C). At 1C, the second discharge specific capacity is 98.46 mAh·g−1. After 100 cycles, the Rct was 2.92 × 10−2 Ω. The NaTi2(PO4)3/C//LiMn2O4 full cell can provide a discharge specific capacity of up to 101.07 mAh·g−1. The synthesized NaTi2(PO4)3/C material can be applied to the anode electrode of hybrid aqueous lithium-ion full cell.