Silver vanadium bronze, β-Ag0.33V2O5: crystal-water-free high-capacity cathode material for rechargeable Ca-ion batteries

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2021-09, Vol.9 (36), p.20776-20782
• Main Authors: Jooeun Hyoung, Heo, Jongwook W, Jeon, Boosik, Seung-Tae, Hong
• Format: Article
• Language: English
• Subjects: Batteries; Calcium; Calcium ions; Cathodes; Crystal structure; Electrode materials; Flux density; Lithium; Lithium-ion batteries; Nonaqueous electrolytes; Rechargeable batteries; Structural stability; Vanadium
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/d1ta03881h

Calcium-ion batteries (CIBs) are getting increasing attention as post-lithium-ion batteries owing to their theoretical and potential advantages in terms of energy density and cost-effectiveness. However, most of the reported cathode materials suffer from low capacity or cyclability in dried nonaqueous electrolytes. So far, all of the materials with high capacity (>100 mA h g−1) contain crystal water, which was considered to be crucial to the structural stability, enabling facile Ca diffusion. Here, we report β-Ag0.33V2O5 as a high-capacity cathode material for CIBs without crystal water. After the initial activation process, the material exhibited a capacity of 179 mA h g−1 at approximately 2.8 V (vs. Ca2+/Ca) in the ninth cycle and showed a modest cycling performance. The capacity is the highest among the Ca cathode materials without crystal water reported to date. We revealed that the activation process was caused by a replacement reaction between the silver and calcium ions. This material demonstrates that crystal water is not an essential component of CIB electrode materials for a high capacity, stimulating the ongoing research for developing higher-performance materials.