Sodium-ion batteries have attracted significant recent attention currently considering the limited available lithium resource. However, the energy density of sodium-ion batteries is still insufficient compared to lithium-ion batteries, mainly because of the unavailability of high-energy cathode materials. In this work, a novel sodium-rich layered oxide material (Na2MnO3) is reported with a dynamical stability similar to that of the Li2MnO3 structure and a high capacity of 269.69 mA·h·g1, based on first-principles calculations. Sodium ion de-intercalation and anionic reaction processes are systematically investigated, in association with sodium ions migration phenomenon and structure stability during cycling of NaxMnO3 (1 ≤ x ≤ 2). In addition, the charge compensation during the initial charging process is mainly contributed by oxygen, where the small differences of the energy barriers of the paths 2c→4h, 4h→2c, 4h→4h, 2c→2b, and 4h→2b indicate the reversible sodium ion occupancy in transitional metal and sodium layers. Moreover, the slow decrease of the elastic constants is a clear indication of the high cycle stability. These results provide a framework to exploit the potential of sodium-rich layered oxide, which may facilitate the development of high-performance electrode materials for sodium-ion batteries.
Project suppoted by the National Natural Science Foundation of China (Grant Nos. 11774017, 51761135129, and 51472010) and Beijing Municipal High Level Innovative Team Building Program, China (Grant No. IDHT20170502).
Gen-Cai Guo, Changhao Wang, Bang-Ming Ming, Si-Wei Luo, Heng Su, Bo-Ya Wang, Ming Zhang, Hai-Jun Yu, Ru-Zhi Wang. High capacity sodium-rich layered oxide cathode for sodium-ion batteries[J]. Chin. Phys. B, 2018, 27(11): 118801.