Ramifications of Water-in-Salt Interfacial Structure at Charged Electrodes for Electrolyte Electrochemical Stability

• DOI: 10.1021/acs.jpclett.7b01879
• Publication Date: 2017-08-28T18:49:43Z
• Authors: Jenel Vatamanu; Oleg Borodin
• Keywords: Passivation; Electrochemical window

Development of safe aqueous batteries and supercapacitors critically relies on expanding the electrolyte electrochemical stability window. A novel mechanism responsible for widening window water-in-salt electrolytes (WiSEs) compared to conventional salt-in-water is suggested based molecular dynamics (MD) simulations electrolyte-electrode interface. Water exclusion from interfacial layer at positive electrode provided additional kinetic protection that delayed onset oxygen evolution reactions. The structure a WiSE negative electrodes near potential zero charge clarified why recently discovered passivation layers formed in WiSEs are robust. water accumulation potentials below 1.5 V vs Li/Li+ leads formation water-rich nanodomains electrode, limiting robustness WiSE. Unexpectedly, bis(trifluoromethanesulfonyl)imide anion adsorbed trifluoromethanesulfonate desorbed with polarization, demonstrating selective partitioning double layer.