Oxygen-Vacancy-Rich Na1.3Ti1.8Ni0.1Sb0.1(PO4)3@C Anode for High-Rate and Low-Temperature Sodium-Ion Storage

NASICON-type NaTi 2 (PO 4 ) 3 as an electrode material for sodium-ion batteries has attracted considerable attention due to its high structural stability and safety, yet its low intrinsic electronic conductivity limits high-rate and low-temperature performance. In this work, an oxygen-vacancy-rich Na 1.3 Ti 1.8 Ni 0.1 Sb 0.1 (PO 4 ) 3 @C (N 1.3 T 1.8 N 0.1 S 0.1 P@C) nanopowder as a high-performance anode material is synthesized by a solvothermal method. The Ni 2+ /Sb 5+ co-doping effectively modulates the local TiO 6 /PO 4 lattice environment, introduces oxygen vacancies, and optimizes the lattice electronic structure, enhancing both electron and ion transport. A continuous carbon coating forms a stable conductive network, further improving kinetics and structural integrity. As a result, Na∥N 1.3 T 1.8 N 0.1 S 0.1 P@C half-cells retain 91% of their capacity after 5000 cycles at 20 C and maintain 86% capacity over 10,000 cycles at 10 C under 0 ° C. The full cell paired with Na 3 V 2 (PO 4 ) 3 cathodes exhibits 87% capacity retention after 1000 cycles at 5 C and delivers excellent performance even at 50 C without pre-sodiation, highlighting their potential for low-temperature applications. This study provides a general doping-defect engineering strategy for NASICON-type anodes, enabling high-rate, low-temperature, and long-cycle performance for sodium-ion batteries.