Regulating zinc-ion deposition kinetics by addition of carboxymethyl cellulose in hydrogel electrolyte for rechargeable zinc batteries

The growth of zinc dendrites severely restricts the development of aqueous zinc-ion batteries (AZIBs). Functional hydrogel electrolytes show promising potential for AZIBs with good reversibility and versatility. In this work, carboxymethyl cellulose (CMC) was introduced into the polyacrylamide hydrogel electrolyte (denoted as CMC/PAM) with expanded electrochemical stability window and favorable ionic conductivity. More importantly, CMC/PAM hydrogel electrolyte regulates the migration behavior of zinc ions with high zinc ion transference number (0.49), low desolvation energy (36.17 kJ mol⁻¹), and preferential deposition on the Zn(002) crystal plane. These characteristics significantly improves the cycle life of the zinc anode. The Zn||Zn symmetric cell with CMC/PAM shows a cycling life of 1800 h at 0.5 mA cm⁻² and 0.5 mAh cm⁻². Moreover, a pouch battery Zn||MnO₂@CNT using CMC/PAM as hydrogel electrolyte and conductive carbon black (Super P)-modified zinc foil as anode, stably cycled over 200 cycles at 0.2 A g⁻¹ under a high cathode loading of 12 mg cm⁻². Specially, a 1.1-Ah laminated pouch battery operated stably for 77 cycles. This work provides a new perspective to accelerate the industrialization of AZIBs with a satisfactory lifespan.