Luo Hao, Wang Bo, Wang Fei, Yang Jing, Wu Fangdong, Ning Yu, Zhou Yu, Wang Dianlong, Liu Huakun, Dou Shixue
MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, No. 92 West Dazhi Street, 150001 Harbin, China.
School of Materials Science and Engineering, Harbin Institute of Technology, 150001 Harbin, China.
ACS Nano. 2020 Jun 23;14(6):7328-7337. doi: 10.1021/acsnano.0c02658. Epub 2020 May 29.
The lack of suitable cathodes is one of the key reasons that impede the development of aqueous zinc-ion batteries. Because of the inherently unsuitable structure and inferior physicochemical properties, the low-valent VO as Zn host could not be effectively discharged. Herein, we demonstrate that VO (theoretical capacity up to 715 mAh g) can be utilized as a high-performance cathode material by an anodic oxidation strategy. Through simultaneously regulating the concentration of the electrolyte and the morphology of the VO sample, the ultraefficient anodic oxidation process of the VO cathode was achieved within the first charging, and the mechanism was also schematically investigated. As expected, the VO cathode with a hierarchical microcuboid structure achieved a nearly two-electron transfer process, enabling a high discharging capacity of 625 mAh g at 0.1 A g (corresponding to a high energy density of 406 Wh kg) and cycling stability (100% capacity retention after 10 000 cycles). This work not only sheds light on the phase transition process of low-valent VO but also exploits a method toward design of advanced cathode materials.
缺乏合适的阴极是阻碍水系锌离子电池发展的关键原因之一。由于其固有的不合适结构和较差的物理化学性质，低价态的VO作为锌宿主时无法有效脱锌。在此，我们证明VO（理论容量高达715 mAh g）可通过阳极氧化策略用作高性能阴极材料。通过同时调节电解液浓度和VO样品的形貌，VO阴极在首次充电时实现了超高效阳极氧化过程，并对其机理进行了示意性研究。正如预期的那样，具有分级微立方结构的VO阴极实现了近两电子转移过程，在0.1 A g下具有625 mAh g的高放电容量（对应于406 Wh kg的高能量密度）和循环稳定性（10000次循环后容量保持率为100%）。这项工作不仅揭示了低价态VO的相变过程，还开发了一种设计先进阴极材料的方法。
