Design Considerations of Ionic Conductive Elastomeric Electrolyte for Solid‐State Zinc Metal Batteries with High Safety and Long Life

Zn-ion batteries are regarded as one of the most promising candidates for energy storage, but the severe hydrogen evolution reaction (HER) and dendrite growth have impeded their application. In this study, we developed an Zn²⁺-ionic conductive elastomer solid-state electrolyte through the simultaneous hydrogen-bond cross-linking between phytic acid (PA) molecules and polyvinyl alcohol (PVA). The large PA molecules inside the polymer electrolyte are favorable to maintaining stretched conformation of PVA chain and uniform interpenetrating distribution, enhancing the amorphous region of PVA polymer. And the high-density hydrogen bond network constructed from PVA chains and PA molecules builds a novel transport mode to promote the efficient Zn²⁺ ion transport, displaying significant ion conductivity of 6.05 mS cm^-1 at 30 °C and a higher transference number of 0.68. The special viscoelasticity of the elastomer facilitates close contact with electrodes, ensuring superior interface compatibility. The assembled Zn symmetric battery exhibits a stable cycle life of 2880 h under 0.5 mA cm^-2/0.5 mAh cm^-2, and the assembled Zn//VO₂ full battery still maintains a capacity retention rate of 86.5% at 400 cycles under 1.0 A g^-1. The development of ionic conductive elastomers offers a novel approach to solve the solid-state interface design of solid-state Zn-ion batteries.