Enhanced Electrochemical Performance of Ca-Doped Na3V2(PO4)2F3/C Cathode Materials for Sodium-Ion Batteries

Diah Agustina Puspitasari, Jagabandhu Patra, Rahmandhika Firdauzha Hary Hernandha, Yu Shen Chiang, Atsushi Inoishi, Bor Kae Chang, Tai Chou Lee, Jeng Kuei Chang

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Na3V2(PO4)2F3 (NVPF) with a NASICON structure has garnered attention as a cathode material owing to its stable 3D structure, rapid ion diffusion channels, high operating voltage, and impressive cycling stability. Nevertheless, the low intrinsic electronic conductivity of the material leading to a poor rate capability presents a significant challenge for practical application. Herein, we develop a series of Ca-doped NVPF/C cathode materials with various Ca2+ doping levels using a simple sol-gel and carbon thermal reduction approach. X-ray diffraction analysis confirmed that the inclusion of Ca2+ does not alter the crystal structure of the parent material but instead expands the lattice spacing. Density functional theory calculations depict that substituting Ca2+ ions at the V3+ site reduces the band gap, leading to increased electronic conductivity. This substitution also enhanced the structural stability, preventing lattice distortion during the charge/discharge cycles. Furthermore, the presence of the Ca2+ ion introduces two localized states within the band gap, resulting in enhanced electrochemical performance compared to that of Mg-doped NVPF/C. The optimal NVPF-Ca-0.05/C cathode exhibits superior specific capacities of 124 and 86 mAh g-1 at 0.1 and 10 C, respectively. Additionally, the NVPF-Ca-0.05/C demonstrates satisfactory capacity retention of 70% after 1000 charge/discharge cycles at 10 C. These remarkable results can be attributed to the optimized particle size, excellent structural stability, and enhanced ionic and electronic conductivity induced by the Ca doping. Our findings provide valuable insight into the development of cathode material with desirable electrochemical properties.

Original languageEnglish
Pages (from-to)496-506
Number of pages11
JournalACS Applied Materials and Interfaces
Volume16
Issue number1
DOIs
StatePublished - 10 Jan 2024

Keywords

  • Ca doping
  • cycling stability
  • density functional theory
  • electronic conductivity
  • Na-ion transport

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