Lattice engineering of Zn-doped Na3V2(PO4)2F3 for high-rate, wide-temperature sodium-ion batteries

Abstract

Zinc-doped Na₃V₂(PO₄)₂F₃ emerges as a promising high-performance cathode material for sodium-ion batteries. In this work, we highlight the critical role of lattice fine-tuning, which was often overlooked in favor of improving electronic conductivity, as a key factor in enhancing sodium-ion mobility and ensuring long-term structural stability. This insight introduces a new design paradigm for robust cathode materials that can operate at high rates across a wide temperature range. Zn-doped NVPF (NVZ_0.03PF@C) demonstrates that subtle lattice modifications can significantly boost electrochemical performance. Density functional theory (DFT) calculations reveal the material design strategy, with a reduction in bandgap, which correlates with enhanced electronic conductivity and improved ion transport. The lattice expansion and the Zn²⁺-induced “pillar effect” reinforce the crystal structure, enabling superior rate capability and cycling performance, even under ultra-high current densities. Notably, the material exhibits almost 100 % capacity retention after 1000 and 2000 cycles at 10C and 20C, respectively, at room temperature. Furthermore, a full-cell composed of NVP//NVZ_0.03PF@C demonstrates excellent capacity retention, achieving 88 % at room temperature and 94 % at −20 °C, confirming its robustness across a wide temperature range. These findings position Zn-doped NVPF as an up-and-coming cathode candidate for high-rate, wide-temperature-range sodium-ion battery applications.