Stable Potassium Metal Anodes with an All-Aluminum Current Collector through Improved Electrolyte Wetting |
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Authors: | Pengcheng Liu Yixian Wang Hongchang Hao Swastik Basu Xuyong Feng Yixin Xu Jorge Anibal Boscoboinik Jagjit Nanda John Watt David Mitlin |
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Affiliation: | 1. Materials Science and Engineering Program & Texas Materials Institute (TMI), The University of Texas at Austin, Austin, TX, 78712-1591 USA;2. Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, NY, 11973 USA;3. Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37830 USA;4. Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM, 87545 USA |
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Abstract: | This is the first report of successful potassium metal battery anode cycling with an aluminum-based rather than copper-based current collector. Dendrite-free plating/stripping is achieved through improved electrolyte wetting, employing an aluminum-powder-coated aluminum foil “Al@Al,” without any modification of the support surface chemistry or electrolyte additives. The reservoir-free Al@Al half-cell is stable at 1000 cycles (1950 h) at 0.5 mA cm?2, with 98.9% cycling Coulombic efficiency and 0.085 V overpotential. The pre-potassiated cell is stable through a wide current range, including 130 cycles (2600 min) at 3.0 mA cm?2, with 0.178 V overpotential. Al@Al is fully wetted by a 4 m potassium bis(fluorosulfonyl)imide-dimethoxyethane electrolyte (θCA = 0 ° ), producing a uniform solid electrolyte interphase (SEI) during the initial galvanostatic formation cycles. On planar aluminum foil with a nearly identical surface oxide, the electrolyte wets poorly (θCA = 52 ° ). This correlates with coarse irregular SEI clumps at formation, 3D potassium islands with further SEI coarsening during plating/stripping, possibly dead potassium metal on stripped surfaces, and rapid failure. The electrochemical stability of Al@Al versus planar Al is not related to differences in potassiophilicity (nearly identical) as obtained from thermal wetting experiments. Planar Cu foils are also poorly electrolyte-wetted and become dendritic. The key fundamental takeaway is that the incomplete electrolyte wetting of collectors results in early onset of SEI instability and dendrites. |
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Keywords: | lithium metal batteries lithium–sulfur batteries potassium-ion batteries potassium–sulfur batteries sodium metal batteries |
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