Abstract
The NASICON-structured Na2VTi(PO4)3 (NVTPO) has attracted significant attention due to its exceptional structural stability and rapid Na+ mobility. However, the development of this material has been hindered by poor electronic conductivity and inadequate low-temperature performance. Herein, a feasible strategy of lattice regulation integrated with surface modification for NVTPO by nitrogen (N) deep doping is proposed. Systematic characterizations and theoretical calculations confirm that N is doped into both the inner crystal structure of NVTPO and the outer carbon layer. The blueshift of the P–O bonds and charge redistribution induced by the V/Ti–N bonds strengthen the local environment and narrow the bandgap, thereby enabling reversible structural evolution and improving electronic conductivity. As expected, the optimized NVTPO/N@CN material achieves an ultra-high capacity of 188.48 mA h g−1 at 10 mA g−1 and a long-term lifespan of 2000 cycles at 1 A g−1. More importantly, it exhibits competitive low-temperature performance (92.15% retention after 1000 cycles at 300 mA g−1 and −15°C) due to reduced charge transfer impedance and activation energy. This deep doping strategy modification is expected to broaden the applications of NASICON-type cathodes.
Published Version
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