Zwitterion as electrical double layer regulator to in-situ formation of fluorinated interphase towards stable zinc anode

The issues of serious corrosion and dendrite growth in electrode surface hinder the commercialization of aqueous zinc batteries. A stable solid electrolyte interphase (SEI) on electrode surface is critical to improve electrochemical performance of Zn anode. Here, a novel zwitterion additive as an electrical double layer (EDL) regulator with SEI-forming capability is developed. The zwitterion exhibits preferential adsorption with Zn anode to construct a fast Zn2+ migration channel. More importantly, a ZnF2 SEI layer can be in-situ generated on the anode due to preferential electroreduction of zwitterion, which isolates Zn anode from electrolytes. Therefore, the symmetric cells with the proposed electrolyte survive long cycling stability over 600 h at 10 mA cm−2 and 10 mAh cm−2. The merits of zwitterion additive are further demonstrated in the Zn||V2O5·nH2O full cell with a capacity retention of ∼80% after 1000 cycles.