Controlling Interfacial Structural Evolution in Aqueous Electrolyte via Anti‐Electrolytic Zwitterionic Waterproofing

Abstract

AbstractAqueous electrolytes are considered as an alternative to flammable and toxic organic electrolytes, whose broad applications in electrochemical energy storage (EES) devices unfortunately suffer from low electrochemical stability due to the easy electrolysis of water. Here, by performing in situ transmission electron microscope electrochemical characterizations at atomic resolution during charging/discharging, an anti‐electrolytic strategy is revealed in aqueous electrolytes via physical zwitterionic waterproofing. It is found that the zwitterionic molecules can be directionally adsorbed to the negative electrode's surface under the applied electric field, forming strings of zwitterionic molecules that extract water out from the electrode. More zwitterionic molecules further aggregate at the outer end of the strings through intermolecular electrostatic interactions, forming a waterproof layer that successfully expels water from the electrode's surface. Meanwhile, the self‐aggregation of zwitterionic additives in the bulk liquid successfully minimizes the influence on ion transport. Being intrinsically distinct from the solid electrolyte interphase concept associated with certain electrochemical reactions in organic or super‐concentrated electrolytes, the strategy is effective in improving the electrochemical stability while maintaining high ionic conductivity in various aqueous electrolytes even with a dilute concentration, shedding light on developing sustainable EES devices with high performance.