Ultra-stable and highly reversible aqueous zinc metal anodes with high preferred orientation deposition achieved by a polyanionic hydrogel electrolyte

Although aqueous zinc metal batteries (AZMBs) have attractive advantages such as high safety, low cost and eco-friendliness, severe dendrites formation and side reactions of zinc metal anodes cause a serious challenge for commercial applications. Herein, a polyanionic hydrogel electrolyte, poly 2-acrylamido-2-methyl-1-propane sulfonate zinc (PAMPSZn) is firstly designed and synthesized by ion exchange and free-radical polymerization. The PAMPSZn hydrogel electrolyte owns fixed polyanionic chain and restricted Zn2+ transport channels, which can effectively alleviate the side reactions and prevent the formation of Zn dendrites simultaneously. Consequently, the anode-friendly electrolyte not only enables ultra-stable Zn plating/stripping over 4500 h at 1.0 mA cm−2, but also achieves high preferred orientation deposition during the procedure of repeated plating/stripping. It delivers high reversibility with high initial coulombic efficiency (87.5%) and average coulombic efficiency (99.3%) in Zn/Cu cells at 0.5 mA cm−2. Zn/V2O5 cells with the developed electrolyte also possess outstanding cycle stability with capacity retention of 80.2% after 400 cycles at 0.5 A g−1. The PAMPSZn hydrogel electrolyte with unique fixed polyanionic chain and restricted Zn2+ transport channels demonstrates an effective strategy to solve both dendrites formation and side reactions in AZMBs, providing a new opportunity for high performance AZMBs.