Reactivity at the Lithium鈥揗etal Anode Surface of Lithium鈥揝ulfur Batteries
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- 作者：Luis E. Camacho-Forero ; Taylor W. Smith ; Samuel Bertolini ; Perla B. Balbuena
- 刊名：Journal of Physical Chemistry C
- 出版年：2015
- 出版时间：December 3, 2015
- 年：2015
- 卷：119
- 期：48
- 页码：26828-26839
- 全文大小：700K
- ISSN：1932-7455
文摘
Due to their high energy density and reduced cost, lithium鈥搒ulfur batteries are promising alternatives for applications such as electrical vehicles. However, a number of technical challenges need to be overcome in order to make them feasible for commercial uses. These challenges arise from the battery highly interconnected chemistry, which besides the electrochemical reactions includes side reactions at both electrodes and migration of soluble polysulfide (PS) species produced at the cathode to the anode side. The presence of such PS species alters the already complex reactivity of the Li anode. In this work, interfacial reactions occurring at the surface of Li metal anodes due to electrochemical instability of the electrolyte components and PS species are investigated with density functional theory and ab initio molecular dynamics methods. It is found that the bis(trifluoromethane)sulfonimide lithium salt reacts very fast when in contact with the Li surface, and anion decomposition precedes salt dissociation. The anion decomposition mechanisms are fully elucidated. Two of the typical solvents used in Li鈥揝 technology, 1,3-dioxolane and 1,2-dimethoxyethane, are found stable during the entire simulation length, in contrast with the case of ethylene carbonate that is rapidly decomposed by sequential 2- or 4-electron mechanisms. On the other hand, the fast reactivity of the soluble PS species alters the side reactions because the PS totally decomposes before any of the electrolyte components forming Li2S on the anode surface.