Unveiling the abnormal capacity rising mechanism of MoS2 anode during long-term cycling for sodium-ion batteries. Issue 46 (24th August 2021)

• Record Type: Journal Article
• Authors: Zhu, Yucheng; Li, Haoyu; Wu, Yuanming; Yang, Liwen; Sun, Yan; Chen, Guang; Liu, Yang; Wu, Zhenguo; Zhang, Chuhong; Guo, Xiaodong
• Is Part Of: RSC advances. Volume 11:Issue 46(2021)
• Page Start: 28488
• Page End: 28495
• Publication Date: 2021-08-24
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/d1ra05518f
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : The capacity rising is due to the biphasic coexistence of MoS2 during the cycling and the progressive increase in the 1T-MoS2 content. Simultaneously, the layer spacing expanded from 0.62 nm to 1.03 nm during the cycling process. Abstract : 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 (MoS2 ) 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 MoS2 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 MoS2 (2H-MoS2 ) to the trigonal phase MoS2 (1T-MoS2 ). Moreover, the ratio of 1T-MoS2 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.