Design of Hydrogel Electrolytes Using Strong Bacterial Cellulose with Weak Ionic Interactions

Abstract

Hydrogel electrolytes with both high ionic conductivity and sufficient mechanical strength are in great demand but remain a long-standing challenge. Here, we report a simple method to fabricate highly conductive and strong hydrogels (IBVA) by leveraging a layered cellulose network with weak ionic interactions. Specifically, bacterial cellulose (BC) membranes with high crystallinity and mechanical strength are employed as the strong skeletons of the hydrogel matrix. Simultaneously, formate anions with a salting-in effect are introduced to tune the aggregation states of polymer chains, endowing the hydrogel with weak hydrogen bonding, and finally forming a "hard-soft-hard" interlocking hierarchical structure. This strategy enables the hydrogel to achieve an ultrahigh ionic conductivity of 105 ± 5 mS cm^-1, alongside satisfying mechanical strength (0.78 MPa), outperforming most reported hydrogel electrolytes. Furthermore, the IBVA hydrogel was successfully demonstrated as an electrolyte for supercapacitors, exhibiting the favorable flexibility, broad temperature adaptability, interfacial stability, and stable electrochemical performance. Our proposed method establishes a framework for engineering high-performance hydrogel electrolytes tailored for flexible electronics.