Zhu Yucheng, Li Haoyu, Wu Yuanming, Yang Liwen, Sun Yan, Chen Guang, Liu Yang, Wu Zhenguo, Zhang Chuhong, Guo Xiaodong
College of Chemical Engineering, Sichuan University Chengdu 610065 Sichuan China
School of Mechanical Engineering, Chengdu University Chengdu 610106 Sichuan China.
RSC Adv. 2021 Aug 24;11(46):28488-28495. doi: 10.1039/d1ra05518f. eCollection 2021 Aug 23.
Transition metal sulfides are considered as one of the most potential anode materials in sodium-ion batteries due to their high capacity, low cost, and rich resources. Among plenty of options, molybdenum sulfide (MoS) has been the focus of research due to the graphene-like layered structure and unique electrochemical properties. Importantly, an abnormal capacity increase phenomenon was observed in the MoS anode of sodium-ion batteries, but the mechanisms involved are still unclear. In this study, by analyzing the composition and structure of the material after a different number of cycles, we confirmed that the (002) plane shows a significant expansion of the interlayer spacing after the sodium ion insertion process and a phase transformation from the hexagonal phase MoS (2H-MoS) to the trigonal phase MoS (1T-MoS). Moreover, the ratio of 1T-MoS presented an increasing trend during cycling. The dual-phase co-existence leads to enhanced electrical conductivity, higher Na affinity, and higher Na mobility, thus increasing the capacity. Our work provides a new perspective on the anomalous electrochemical behavior of sulfide anodes during long-term cycling.
过渡金属硫化物因其高容量、低成本和丰富的资源，被认为是钠离子电池中最具潜力的负极材料之一。在众多选择中，硫化钼（MoS）因其类石墨烯层状结构和独特的电化学性质而成为研究热点。重要的是，在钠离子电池的MoS负极中观察到了异常的容量增加现象，但其涉及的机制仍不清楚。在本研究中，通过分析不同循环次数后材料的组成和结构，我们证实了在钠离子嵌入过程后，（002）面的层间距显著扩大，并且发生了从六方相MoS（2H-MoS）到三方相MoS（1T-MoS）的相变。此外，在循环过程中1T-MoS的比例呈上升趋势。双相共存导致电导率增强、对Na的亲和力更高以及Na迁移率更高，从而提高了容量。我们的工作为长期循环过程中硫化物负极的异常电化学行为提供了新的视角。
