Unraveling the structural mechanism of Li insertion in γ′-V2O5 and its effect on cycling properties
Unraveling the structural mechanism of Li insertion in γ′-V2O5 and its effect on cycling properties
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DOI：
10.1016/j.actamat.2018.11.043
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发表时间：
2019-02-15
期刊：
影响因子：
9.4
通讯作者：
Pereira-Ramos, J. P.
中科院分区：
文献类型：
--
作者：
Baddour-Hadjean, R.;Renard, M. Safrany;Pereira-Ramos, J. P.
我们首次报道了伽马‘-V2O5多晶型向Li插入的电化学和结构研究，在4V-2.4V，3.6V-2.4V和4V-2.15V的电势范围内评估了循环性能。这种正极材料是通过使用强氧化剂从三元合金-LiV2O5青铜中通过拓扑定向脱锂而合成的。它在3.58/3.47V和2.42/2.36V处有两对明确的可逆台阶，其间有约1V的急剧电位降。在4.00V-2.15V的电压窗口内，插入近2Li/摩尔的氧化物对应的高比容量为285mAHg(-1)。当低截止电压限制在2.4V时，伽马‘-V2O5材料在C/10的45次循环中可以提供120-185mAHg(-1)的稳定比容量，但在最宽的4.00V-2.15V电势范围内循环实验导致容量显著下降。详细的X射线衍射和拉曼光谱研究提供了伽马‘-V2O5中随Li含量变化而发生的结构变化的详细图像。在扩展的4.00V-2.15V电压范围内的第一次放电-充电循环期间，即在0。
We report the first electrochemical and structural study of the gamma'-V2O5 polymorph toward Li insertion, with cycling properties evaluated in the 4 V-2.4 V, 3.6 V-2.4 V and 4 V-2.15 V potential ranges. This cathode material is synthesized through topotactic lithium removal from the ternary gamma-LiV2O5 bronze, using a strong oxidizing agent. It exhibits two pairs of well-defined reversible steps at 3.58/3.47 V and 2.42/2.36 V separated by a sharp potential drop of about 1 V. A high specific capacity of 285 mAh g(-1) is involved in the 4.00 V-2.15 V voltage window corresponding to the insertion of nearly 2 Li/mole of oxide. The gamma'-V2O5 material can deliver stable specific capacities of 120-185 mAh g(-1) over 45 cycles at C/10 when the lower cut-off voltage is limited to 2.4 V. Cycling experiments in the widest 4.00 V-2.15 V potential range induce however a significant capacity decline. A detailed XRD and Raman spectroscopy study delivers a detailed picture of the structural changes occurring in gamma'-V2O5 as a function of Li content. A complete phase diagram of the gamma'-V2O5/Li system is provided during the first discharge-charge cycle in the extended 4.00 V-2.15 V voltage range, i.e. for 0