Carboxyl-functionalized bacterial cellulose/alginate dual network hydrogel electrolyte with high ionic conductivity for zinc-ion batteries.

Aqueous zinc-ion batteries (ZIBs) represent a transformative energy storage technology for next-generation flexible electronics, yet their practical implementation has been constrained by persistent challenges including uncontrolled zinc dendrite growth and the inherent trade-off between ionic conductivity (IC) and mechanical strength of hydrogel electrolytes. In this study, a hydrogel electrolyte (SBD) was fabricated by combining sodium alginate (SA) with diethylenetriaminepentaacetic acid (DTPA)-functionalized bacterial cellulose (BC). Its hierarchically porous 3D network and abundant carboxylate groups (-COO-) simultaneously homogenized Zn2+ flux, constructed favorable spatial coordination sites for Zn2+, and strengthened mechanical integrity. The electrolyte exhibited an IC of 45.5 mS cm-1, a tensile strength of 435 kPa, and a Zn2+ transference number (tZn2+) of 0.71. The as-assembled Zn/SBD/Zn symmetric cell delivered stable cycling over 3500 h at 1 mA cm-2, while the Zn/SBD/MnO2 full cell maintained 76.9% capacity retention after 500 cycles. Flexible Zn/SBD/MnO2 batteries retained stable electrochemical performance under bending deformation, indicating their potential for durable wearable energy storage applications.