Li2S Film Formation on Lithium Anode Surface of Li–S batteries

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• 作者：Zhixiao Liu ; Samuel Bertolini ; Perla B. Balbuena ; Partha P. Mukherjee
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2016
• 出版时间：February 24, 2016
• 年：2016
• 卷：8
• 期：7
• 页码：4700-4708
• 全文大小：618K
• ISSN：1944-8252

文摘

The precipitation of lithium sulfide (Li₂S) on the Li metal anode surface adversely impacts the performance of lithium–sulfur (Li–S) batteries. In this study, a first-principles approach including density functional theory (DFT) and ab initio molecular dynamics (AIMD) simulations is employed to theoretically elucidate the Li₂S/Li metal surface interactions and the nucleation and growth of a Li₂S film on the anode surface due to long-chain polysulfide decomposition during battery operation. DFT analyses of the energetic properties and electronic structures demonstrate that a single molecule adsorption on Li surface releases energy forming chemical bonds between the S atoms and Li atoms from the anode surface. Reaction pathways of the Li₂S film formation on Li metal surfaces are investigated based on DFT calculations. It is found that a distorted Li₂S (111) plane forms on a Li(110) surface and a perfect Li₂S (111) plane forms on a Li(111) surface. The total energy of the system decreases along the reaction pathway; hence Li₂S film formation on the Li anode surface is thermodynamically favorable. The calculated difference charge density of the Li₂S film/Li surface suggests that the precipitated film would interact with the Li anode via strong chemical bonds. AIMD simulations reveal the role of the anode surface structure and the origin of the Li₂S formation via decomposition of Li₂S₈ polysulfide species formed at the cathode side and dissolved in the electrolyte medium in which they travel to the anode side during battery cycling.