Wang Jinjin, Wang Jian-Gan, Qin Xueping, Wang Yian, You Zongyuan, Liu Huanyan, Shao Minhua
State Key Laboratory of Solidification Processing, Center for Nano Energy Materials, School of Materials Science and Engineering, Northwestern Polytechnical University and Shaanxi Joint Laboratory of Graphene (NPU), Xi'an 710072, China.
Department of Chemical and Biological Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
ACS Appl Mater Interfaces. 2020 Aug 5;12(31):34949-34958. doi: 10.1021/acsami.0c08812. Epub 2020 Jul 26.
The core challenge of MnO as the cathode material of zinc-ion batteries remains to be their poor electrochemical kinetics and stability. Herein, MnO superfine nanowires (∼10 nm) with rich crystal defects (oxygen vacancies and cavities) are demonstrated to possess high efficient zinc-ion storage capability. Experimental and theoretical studies demonstrate that the defects facilitate the adsorption and diffusion of hydrogen/zinc for fast ion transportation and the build of a local electric field for improved electron migration. In addition, the superfine nanostructure could provide sufficient active sites and short diffusion pathways for further promotion of capacity and reaction kinetics of MnO. Remarkably, the defect-enriched MnO nanowires manifest an energy density as high as 406 W h kg and an excellent durability over 1000 cycles without noticeable capacity degradation. Mechanistic analysis substantiates a reversible coinsertion/extraction process of H and Zn with a simultaneous deposition/dissolution of zinc sulfate hydroxide hydrate nanoflakes. This work could enrich the fundamental understanding of defect engineering and nanostructuring on the development of advanced MnO materials toward high-performance zinc-ion batteries.
二氧化锰作为锌离子电池的阴极材料，其核心挑战仍然是较差的电化学动力学和稳定性。在此，具有丰富晶体缺陷（氧空位和空洞）的二氧化锰超细纳米线（约10纳米）被证明具有高效的锌离子存储能力。实验和理论研究表明，这些缺陷有助于氢/锌的吸附和扩散，以实现快速离子传输，并构建局部电场以改善电子迁移。此外，超细纳米结构可为进一步提高二氧化锰的容量和反应动力学提供足够的活性位点和短扩散路径。值得注意的是，富含缺陷的二氧化锰纳米线表现出高达406瓦时/千克的能量密度，并且在1000次循环中具有出色的耐久性，容量没有明显下降。机理分析证实了氢和锌的可逆共嵌入/脱出过程，同时伴有氢氧化锌硫酸盐氢化物纳米片的沉积/溶解。这项工作可以丰富对缺陷工程和纳米结构在开发用于高性能锌离子电池的先进二氧化锰材料方面的基本理解。
