Li Li, Zhang Wenchao, Wang Xing, Zhang Shilin, Liu Yajie, Li Minhan, Zhu Guanjia, Zheng Yang, Zhang Qing, Zhou Tengfei, Pang Wei Kong, Luo Wei, Guo Zaiping, Yang Jianping
State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, International Joint Laboratory for Advanced Fiber and Low-dimension Materials, College of Materials Science and Engineering , Donghua University , Shanghai 201620 , People's Republic of China.
Institute for Superconducting and Electronic Materials, Australian Institute for Innovative Materials , University of Wollongong , Innovation Campus , North Wollongong , NSW 2500 , Australia.
ACS Nano. 2019 Jul 23;13(7):7939-7948. doi: 10.1021/acsnano.9b02384. Epub 2019 Jun 26.
Due to the abundant potassium resource on the Earth's crust, researchers now have become interested in exploring high-performance potassium-ion batteries (KIBs). However, the large size of K would hinder the diffusion of K ions into electrode materials, thus leading to poor energy/power density and cycling performance during the depotassiation/potassiation process. So, few-layered VS nanosheets wrapping a hollow carbon sphere fabricated a facile hollow carbon template induced method could reversibly accommodate K storage and maintain the structure stability. Hence, the as-obtained VS@C electrode enables rapid and reversible storage of K with a high specific capacity of 645 mAh/g at 50 mA/g, a high rate capability, and long cycling stability, with 360 and 190 mAh/g achieved after 500 and 1000 cycles at 500 and 2000 mA/g, respectively. The excellent electrochemical performance is superior to the most existing electrode materials. The DFT calculations reveal that VS nanosheets have high electrical conductivity and low energy barriers for K intercalation. Furthermore, the reaction mechanism of the VS@C electrode in KIBs is probed the synchrotron X-ray diffraction technique, and it indicates that the VS@C electrode undergoes a sequential intercalation (KVS) and conversion reactions (KS) reversibly during the potassiation process.
由于地壳中钾资源丰富，研究人员现在对探索高性能钾离子电池（KIBs）产生了兴趣。然而，钾离子的大尺寸会阻碍钾离子扩散到电极材料中，从而导致在脱钾/钾化过程中能量/功率密度和循环性能较差。因此，采用简便的空心碳模板诱导法制备的包裹空心碳球的少层VS纳米片能够可逆地容纳钾存储并保持结构稳定性。因此，所制备的VS@C电极能够快速、可逆地存储钾，在50 mA/g时具有645 mAh/g的高比容量、高倍率性能和长循环稳定性，在500 mA/g和2000 mA/g下分别循环500次和1000次后，比容量分别达到360 mAh/g和190 mAh/g。其优异的电化学性能优于大多数现有的电极材料。密度泛函理论（DFT）计算表明，VS纳米片具有高电导率和低的钾嵌入能垒。此外，利用同步辐射X射线衍射技术探究了VS@C电极在钾离子电池中的反应机理，结果表明，在钾化过程中，VS@C电极可逆地经历了顺序嵌入（KVS）和转化反应（KS）。
