Modifying hydrogel electrolyte to induce zinc deposition for dendrite-free zinc metal anode

In recent years, flexible devices have promoted extensive research on flexible aqueous Zn-ion batteries (ZIBs). Nevertheless, the dendrite growth on the anode and the poor mechanical properties of the flexible polymer electrolyte have become bottle-necks for the practical applications of flexible ZIBs. Herein, Carboxymethyl cellulose/polyacrylamide (CMC/PAM) hydrogel electrolyte has been constructed for flexible ZIBs. By introducing double-network structure, we dramatically improve the mechanical properties of the hydrogel electrolyte. The electrostatic interaction between carboxyl groups and Zn2+ can evenly induce the deposition of zinc ions on the zinc electrode surface, leading to remarkable reversibility and stability of zinc electrode. Flexible full ZIBs assembled with this electrolyte exhibit competitive electrochemistry performance with 90.18% capacity retention over 500 cycles at 0.308 mA cm−2. Furthermore, such ZIBs offer excellent bending resistance for enduring high mechanical impact. This study provides an effective strategy to address the zinc dendrite issue and reliability of flexible ZIBs.