Ultrahigh-capacity epitaxial deposition of planar Zn flakes enabled by amino-rich adhesive hydrogel electrolytes for durable low-temperature zinc batteries

Aqueous zinc batteries (AZBs) show promising applications in large-scale energy storage and wearable devices, but suffer from poor reversibility of Zn anodes due to zinc dendrites and possible side reactions. We prepared amino-enriched polypyrrole modified polyacrylamide hydrogel for using as electrolytes in AZBs. The proposed electrolyte exhibits excellent adhesiveness of 19.8 kPa at room temperature (RT), high Zn2+ ion conductivity of 17.6 mS cm−1 at -20 °C, superior elongation of over 1000%, and fast self-healing in ten seconds at -30 °C. The proposed electrolyte enables unique epitaxial Zn deposition with ultra-high areal capacity up to 100 mAh cm−2 under 2 mA cm−2 in symmetric zinc cells. Importantly, this electrolyte assembled quasi-solid-state Zn/V2O5 batteries deliver a high capacity of 200 mAh g−1 at 1 A g−1 and a high capacity retention of 96.4% after 2000 cycles at -20 °C, demonstrating the promising features of the hydrogel electrolytes in high-performance AZBs.