Reducing Mg Anode Overpotential via Ion Conductive Surface Layer Formation by Iodine Additive |
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| Authors: | Xiaogang Li Tao Gao Fudong Han Zhaohui Ma Xiulin Fan Singyuk Hou Nico Eidson Weishan Li Chunsheng Wang |
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| Affiliation: | 1. Department of Chemical and Bimolecular Engineering, University of Maryland, College Park, MD, USA;2. College of Materials Science and Engineering, South China University of Technology, Guangzhou, China |
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| Abstract: | Electrolytes that are able to reversibly deposit/strip Mg are crucial for rechargeable Mg batteries. The most studied complex electrolytes based on Lewis acid‐base chemistry are expensive, difficult to be synthesized, and show limited anodic stability. Conventional electrolytes using simple salts such as Mg(TFSI)2 can be readily synthesized, but Mg deposition/stripping in these simple salt electrolytes is accompanied by a large overpotential due to the formation of a surface layer on the Mg metal with a low Mg ion conductivity. Here the overpotential for Mg deposition/stripping in a simple salt, Mg(TFSI)2‐1,2‐dimethoxyethane (DME), electrolyte is significantly reduced by adding a small concentration of iodine (≤50 × 10?3m ) as an additive. Mechanism studies demonstrate that an Mg ion conductive solid MgI2 layer is formed on the surface of the Mg metal and acts as a solid electrolyte interface. With the Mg(TFSI)2‐DME‐I2 electrolyte, a very small voltage hysteresis is achieved in an Mg‐S full cell. |
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| Keywords: | electrochemistry iodine additive Mg(TFSI)2‐DME simple salt electrolyte reduce overpotential sulfur |
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