Ni Wenhao, Ding Qin, Zheng Wanhao, Peng Gongchang, Wang Hao, Xie Zhengwei, Cao Yuliang
Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu 610041, PR China.
University of Chinese Academy of Sciences, Beijing 100039, PR China.
ACS Appl Mater Interfaces. 2024 Nov 27;16(47):64725-64735. doi: 10.1021/acsami.4c13695. Epub 2024 Nov 12.
The NaMnO cathode has attracted enormous interest owing to its low cost, low toxicity, and stable structure, but its practical application is still hindered by the limited sodium storage sites. Element doping is widely used to improve its capacity. However, cation and anion substitution could barely reach a satisfactory compromise between the structural stability and reversible capacity. Herein, we show that the above issue could be overcome via the synergetic effect of W and Al substitution. Combining the electrochemical and in situ X-ray powder diffraction (XRD) measurements, we reveal that the substitution of W effectively facilitates the tunnel-to-layered phase transformation, while the further substitution of Al eliminates the Na/vacancy ordering during the extraction/insertion of Na ions, resulting in a layered NaMnWAlO (NMO-1W5Al) with negligible Na/vacancy ordering upon cycling. In addition, NMO-1W5Al represents a wider Na interlayer spacing to accelerate the diffusion of Na, which improves the rate performance. The high specific capacity, remarkable rate performance, and high cycling stability of NMO-1W5Al are promising for large-scale energy storage systems.
NaMnO 阴极因其低成本、低毒性和稳定的结构而备受关注，但其实际应用仍受到储钠位点有限的阻碍。元素掺杂被广泛用于提高其容量。然而，阳离子和阴离子取代在结构稳定性和可逆容量之间几乎无法达到令人满意的平衡。在此，我们表明上述问题可以通过 W 和 Al 取代的协同效应来克服。结合电化学和原位 X 射线粉末衍射（XRD）测量，我们发现 W 的取代有效地促进了隧道相向层状相的转变，而进一步的 Al 取代消除了 Na 离子脱嵌过程中的 Na/空位有序化，从而形成了循环时 Na/空位有序化可忽略不计的层状 NaMnWAlO（NMO-1W5Al）。此外，NMO-1W5Al 具有更宽的 Na 层间间距，可加速 Na 的扩散，从而提高倍率性能。NMO-1W5Al 的高比容量、出色的倍率性能和高循环稳定性使其在大规模储能系统中具有广阔的应用前景。
