Two-Dimensional WS2@Nitrogen-Doped Graphite for High-Performance Lithium Ion Batteries: Experiments and Molecular Dynamics Simulations
- Authors
- Debela, Tekalign Terfa; Lim, Young Rok; Seo, Hee Won; Kwon, Ik Seon; Kwak, In Hye; Park, Jeunghee; Cho, Won Il; Kang, Hong Seok
- Issue Date
- 7-11월-2018
- Publisher
- AMER CHEMICAL SOC
- Keywords
- tungsten disulfide; nanosheets; lithium ion battery; N-doped graphite; molecular dynamics simulations
- Citation
- ACS APPLIED MATERIALS & INTERFACES, v.10, no.44, pp.37928 - 37936
- Indexed
- SCIE
SCOPUS
- Journal Title
- ACS APPLIED MATERIALS & INTERFACES
- Volume
- 10
- Number
- 44
- Start Page
- 37928
- End Page
- 37936
- URI
- https://scholar.korea.ac.kr/handle/2021.sw.korea/71872
- DOI
- 10.1021/acsami.8b10133
- ISSN
- 1944-8244
- Abstract
- As promising candidates for anode materials in lithium ion batteries (LIB), two-dimensional tungsten disulfide (WS2) and WS2@(N-doped) graphite composites were synthesized, and their electrochemical properties were comprehensibly studied in conjunction with calculations. The WS2 nanosheets, WS2@graphite, and WS2@N-doped graphite (N-graphite) exhibit outstanding cycling performance with capacities of 633, 780, and 963 mA h g(-1), respectively. To understand their lithium storage mechanism, first-principles calculations involving a series of ab initio NVT-NPT molecular dynamics simulations were conducted. The calculated discharge curves for amorphous phase are well matched with the experimental ones, and the capacities reach 620, 743, and 915 mA h g(-1) for WS2, WS2@graphite, and WS2@N-graphite, respectively. The large capacities of the two composites can be attributed to the tendency of W and Li atoms to interact with graphite, suppressing the formation of W metal clusters. In the case of WS2@N-graphite, vigorous amorphization of the N-graphite enhances the interaction of W and Li atoms with the fragmented N-graphite in such a way that unfavorable Li-W repulsion is avoided at very early stage of lithiation. As a result, the volume expansion in WS2@graphite and WS2@N-graphite is calculated to be remarkably small (only 6 and 44%, respectively, versus 150% for WS2). Therefore WS2@(N-)graphite composites are expected to be almost free of mechanical pulverization after repeated cycles, which makes them promising and excellent candidates for high-performance LIBs.
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