School of Physical Sciences, University of Chinese Academy of Sciences , Beijing 100049, China.
State Key Laboratory of Operation and Control of Renewable Energy & Storage Systems, China Electric Power Research Institute , Beijing 100192, China.
ACS Appl Mater Interfaces. 2017 Nov 22;9(46):40215-40223. doi: 10.1021/acsami.7b11282. Epub 2017 Nov 7.
Rechargeable sodium-ion batteries have drawn increasing attention as candidates for the post lithium-ion batteries in large-scale energy storage systems. Layered oxides are the most promising cathode materials and their pure phases (e.g., P2, O3) have been widely investigated. Here we report a series of cathode materials with O3/P2 hybrid phase for sodium-ion batteries, which possesses advantages of both P2 and O3 structures. The designed material, NaNiFeMnO, can deliver a capacity of 86 mAh g with great rate capability and cycling performance. 66% capacity is still maintained when the current rate reaches as high as 10C, and the capacity retention is 90% after 1500 cycles. Moreover, in situ XRD was performed to examine the structure change during electrochemical testing in different voltage ranges, and the results demonstrate 4 V as the optimized upper voltage limit, with which smaller polarization, better structural stability, and better cycling performance are achieved. The results obtained here provide new insights in designing cathode materials with optimal structure and improved performance for sodium-ion batteries.
可充电钠离子电池作为大型储能系统中锂离子电池的替代品，引起了越来越多的关注。层状氧化物是最有前途的正极材料，其纯相（例如 P2、O3）已得到广泛研究。在这里，我们报告了一系列具有 O3/P2 混合相的钠离子电池正极材料，其兼具 P2 和 O3 结构的优点。设计的材料 NaNiFeMnO 具有 86 mAh g 的高容量和出色的倍率性能及循环性能。当电流速率高达 10C 时，仍能保持 66%的容量，经过 1500 次循环后，容量保持率为 90%。此外，进行了原位 XRD 以检查不同电压范围内电化学测试过程中的结构变化，结果表明 4 V 是优化的上限电压，在此电压下可实现更小的极化、更好的结构稳定性和更好的循环性能。这里的结果为设计具有最佳结构和改进性能的钠离子电池正极材料提供了新的思路。
