Sorbitol-modified cellulose hydrogel electrolyte derived from wheat straws towards high-performance environmentally adaptive flexible zinc-ion batteries

Thanks to low manufacturing cost, high safety level, and competitive energy density, flexible aqueous zinc-ion batteries (AZIBs) are very promising for the emerging wearable electronics. However, AZIBs suffer from low zinc stripping/plating reversibility and poor tolerance to sub-zero temperatures. Herein, food-grade sorbitol with abundant hydroxyl groups and longer molecular chain than common cryoprotectants is used to modify cellulose hydrogel electrolyte derived from wheat straws. And concentrated ZnCl2 is utilized in this hydrogel electrolyte to realize water-in-salt effect. The obtained hydrogel electrolyte owns superior mechanical properties, strong adhesion, high transparency, good moldability, rich porosity, ultralow freezing point (-101.5 celcius), and large ionic conductivity (35.4 and 19.7 mS cm-1 at 20 and - 40 degrees C, respectively). Benefiting from excellent antifreezing ability, tuned solvation sheath, and facilitated desolvation process within this hydrogel electrolyte, high zinc stripping/plating reversibility can be achieved from 20 to - 40 degrees C. And the assembled flexible Zn-polyaniline (PANI) battery delivers superior electrochemical performances even under extreme conditions. This work offers new opportunities for the development of environmentally adaptive batteries and the efficient utilization of crop straws.

Automated summary

In this study, a food-grade sorbitol-modified cellulose hydrogel electrolyte with concentrated ZnCl2 was developed, which exhibited excellent mechanical properties, strong adhesion, high transparency, good moldability, rich porosity, ultralow freezing point, and large ionic conductivity. The modified hydrogel electrolyte enabled high zinc stripping/plating reversibility even under extreme temperatures, resulting in superior electrochemical performances in the assembled flexible Zn-PANI battery.