Recent progress and strategic perspectives of high-voltage Na3V2(PO4)2F3 cathode: Fundamentals, modifications, and applications in sodium-ion batteries

Abstract

The NASICON structure of Na3V2(PO4)2F3 (NVPF) separates the valence electrons between the polyanion group and V and regulates the redox coupling energy. As a result, NVPF exhibits a high operating voltage in sodium-ion batteries. However, NVPF cathode material has poor specific capacity and low-rate performance. It is necessary to improve the electrochemical performance by increasing the electronic conductivity and accelerating the ion diffusion rate. Through morphology control, more active sites and ion channels can be provided to enhance rate performance and cycle stability. However, there are few reviews on how to control the morphology of NVPF. Therefore, this paper starts with the factors affecting the morphology of NVPF. The effects of pH value, surfactant, and external additives on its morphology were systematically summarized. On this basis, reasonable strategies, including morphology design, preparation method, structure control, surface modification, and defect engineering, are summarized. This paper provides theoretical support for the development of high-voltage NVPF. It provides inspiration for creating NVPF cathode materials with high specific capacity and high cycle performance.