Building electrode/electrolyte interphases in aqueous zinc batteries via self-polymerization of electrolyte additives.

Aqueous zinc batteries offer promising prospects for large-scale energy storage, yet their application is limited by undesired side reactions at the electrode/electrolyte interface. Here, we report a universal approach for the building of an electrode/electrolyte interphase (EEI) layer on both the cathode and the anode through the self-polymerization of electrolyte additives. In an exemplified Zn||VO·nHO cell, we reveal that the glutamate additive undergoes radical-initiated electro-polymerization on the cathode and polycondensation on the anode, yielding polyglutamic acid-dominated EEI layers on both electrodes. These EEI layers effectively mitigate undesired interfacial side reactions while enhancing reaction kinetics, enabling Zn||VO·nHO cells to achieve a high capacity of 387 mAh g at 0.2 A g and maintain >96.3% capacity retention after 1500 cycles at 1 A g. Moreover, this interphase-forming additive exhibits broad applicability to varied cathode materials, encompassing VS, VS, VO, α-MnO, β-MnO and δ-MnO. The methodology of utilizing self-polymerizable electrolyte additives to construct robust EEI layers opens a novel pathway in interphase engineering for electrode stabilization in aqueous batteries.