Customizing Ion Transport by Anionphilic Nanofiber-Polymer Electrolyte for Stable Zinc Metal Batteries

The formation of zinc metal dendrites and electrolyte side reactions in rechargeable zinc-metal batteries (RZMBs) is closely related to ion transport within the electrolyte. In salt-doped polymer electrolytes, polymer polarity can be used to control ion transport. Here, we report an anionphilic polymer electrolyte with positive relative anion affinity. By introducing a polymer backbone with weak adsorption of cations and another polymer chain with strong adsorption of anions, weakened the cation-dipole coordination for Zn²⁺, which enables promote the dissociation of salt and restrict the migration of anions. The polymer electrolyte-design concept is demonstrated by using polyacrylamide and aramid nanofibers. Prepared anionphilic polymer hydrogel electrolytes effectively inhibited the hydrogen evolution reaction, forming conformal and adherent inorganic-rich solid electrolyte interphase. The anionphilic polymer electrolytes also exhibit high Zn²⁺ transference number (0.71), enabling Zn_0.25V₂O₅ǀǀZn (30 µm) pouch cells (4.9 mAh cm^-2) to achieve high reversibility over 270 cycles.