Ma Yining, Zhou Huaijuan, Zhang Shuming, Gu Sui, Cao Xun, Bao Shanhu, Yao Heliang, Ji Shidong, Jin Ping
State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, 200050, P. R. China.
University of Chinese Academy of Sciences, Beijing, 100049, P. R. China.
Chemistry. 2017 Sep 21;23(53):13221-13232. doi: 10.1002/chem.201702814. Epub 2017 Aug 30.
Nanorods of δ-Ca V O ⋅H O, a straczekite group mineral with an open double-layered structure, have been successfully fabricated by a facile hydrothermal method and can be transformed into the tunnel β geometry (β-Ca V O ) through a vacuum annealing treatment. The generated β-Ca V O still preserves the nanorod construction of δ-Ca V O ⋅H O without substantial sintering and degradation of the nanostructure. As cathode materials, both calcium vanadium bronzes exhibit high reversible capacity, good rate capability, as well as superior cyclability. Compared with the hydrated vanadium bronze, the β-Ca V O nanorods show better cycling performance (81.68 and 97.93 % capacity retention after 200 cycles at 100 and 400 mA g , respectively) and excellent long-term cyclic stability with an average decay of 0.035 % per cycle over 500 cycles at 500 mA g . Note that the double-layered δ-Ca V O ⋅H O electrode irreversibly converts into β-Ca V O phase during the initial Li insertion/extraction process, while in contrast, the β-phase calcium vanadium bronze electrode shows excellent structural stability during cycling. The excellent electrochemical performance demonstrates that the two calcium vanadium bronzes are potential cathode candidates for rechargeable lithium-ion batteries.
具有开放双层结构的层钒钙石族矿物δ-CaVO₂·H₂O的纳米棒已通过简便的水热法成功制备，并且可以通过真空退火处理转变为隧道β型结构（β-CaVO₃）。生成的β-CaVO₃仍保留δ-CaVO₂·H₂O的纳米棒结构，纳米结构没有明显烧结和降解。作为阴极材料，两种钙钒青铜都表现出高可逆容量、良好的倍率性能以及优异的循环性能。与水合钒青铜相比，β-CaVO₃纳米棒显示出更好的循环性能（在100和400 mA g⁻¹下循环200次后容量保持率分别为81.68%和97.93%），并且在500 mA g⁻¹下500次循环中具有优异的长期循环稳定性，平均每次循环衰减0.035%。注意，双层δ-CaVO₂·H₂O电极在初始锂嵌入/脱出过程中不可逆地转变为β-CaVO₃相，而相比之下，β相钙钒青铜电极在循环过程中显示出优异的结构稳定性。优异的电化学性能表明这两种钙钒青铜是可充电锂离子电池潜在的阴极候选材料。
