Multi-stage collaborative design of hierarchical twisted hydrogel electrolytes for aqueous zinc-ion batteries with high capacity, ultralong stability, and mechanical robustness†

Abstract

Aqueous zinc-ion batteries (AZIBs) are promising energy storage systems due to their high theoretical capacity, intrinsic safety, and potentially high cycling stability. However, their practical application is hindered by sluggish Zn-ion transfer, parasitic side reactions, and dendrite growth, leading to their suboptimal capacity and limited cycle lifespan. Herein, we report a bioinspired design of hierarchical twisted hydrogel electrolytes (HTHEs) by establishing a multi-stage collaborative regulation pathway to address these challenges. The HTHEs exhibit a high Zn²⁺ transference number of 0.9 and a wide electrochemical stability window of 2.61 V, effectively suppressing dendrite formation and enhancing Zn²⁺ deposition along the Zn (002) plane. Symmetric cells assembled with the HTHEs demonstrate exceptional cycling stability across a wide range of current densities, while pouch cells achieve an ultra-long cycle life of nearly 10 000 cycles with a high specific capacity of >100 mA h g⁻¹ and a capacity retention of 80%. Notably, these pouch cells display outstanding flexibility and impact resistance, remaining fully operational under folding and even withstanding extreme mechanical stresses, such as those that can even crack walnuts. The multi-stage collaborative regulation pathway in the design of high-performance flexible AZIB electrolytes enhances their potential for next-generation energy storage applications.