Hydrophobic Organic-Electrolyte-Protected Zinc Anodes for Aqueous Zinc Batteries |
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| Authors: | Dr Longsheng Cao Dr Dan Li Tao Deng Qin Li Prof Chunsheng Wang |
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| Institution: | Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, MD, 20742 USA |
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| Abstract: | Aqueous Zn batteries are promising energy-storage devices. However, their lifespan is limited by irreversible Zn anodes owing to water decomposition and Zn dendrite growth. Here, we separate aqueous electrolyte from Zn anode by coating a thin MOF layer on anode and filling the pores of MOF with hydrophobic Zn(TFSI)2-tris(2,2,2-trifluoroethyl)phosphate (TFEP) organic electrolyte that is immiscible with aqueous Zn(TFSI)2–H2O bulk electrolyte. The MOF encapsulated Zn(TFSI)2-TFEP forms a ZnF2-Zn3(PO4)2 solid electrolyte interphase (SEI) preventing Zn dendrite and water decomposition. The Zn(TFSI)2-TFEP@MOF electrolyte protected Zn anode enables a Zn||Ti cell to achieve a high average Coulombic efficiency of 99.1 % for 350 cycles. The highly reversible Zn anode brings a high energy density of 210 Wh kg−1 (of cathode and anode mass) and a low capacity decay rate of 0.0047 % per cycle over 600 cycles in a Zn||MnO2 full cell with a low capacity ratio of Zn:MnO2 at 2:1. |
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| Keywords: | aqueous zinc batteries metal–organic frameworks phase separation reversibility |
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