A Bioinspired Gradient Hydrogel Electrolyte Network with Optimized Interfacial Chemistry toward Robust Aqueous Zinc-Ion Batteries
Qunhao Wang, Jing Huang, Luhe Qi, Mei Li, Sijun Wang, Junqing Chen, Zengyan Sui, Tingting Bi, Qi Tang, Le Yu, Pei Hu, Wei Zhang, Canhui Lu, Chaoji Chen
Abstract
Hydrogel electrolytes are regarded as a promising option for high-performance aqueous zinc-ion batteries (ZIBs), but they frequently fail to balance the reaction kinetics and Zn 2+ deposition stability. Inspired by articular cartilage, here we develop a gradient-networked hydrogel electrolyte comprising poly(vinyl alcohol) (PVA), cellulose nanofiber (CNF), and graphene oxide (GO) for ZIBs. The low-network-density PVA/CNF (PC) hydrogel layer (cathode side) with extensive channels and a higher water content ensures the rapid transport of ions, while the interfacial hydrogel layer in contact with the Zn anode exhibits a high-density PVA/CNF/GO (PCG) network with enriched carboxyl and hydroxyl groups, which facilitates the desolvation of Zn 2+, decreases the activity of water, and homogenizes the Zn 2+ flux. Moreover, the polar oxygen-containing groups in GO endow it with dielectric and electronegative properties, collectively enhancing the Zn 2+ transference numbers and ionic conductivity of the hydrogel electrolyte. Benefiting from such a gradient-networked structure and modulated interfacial chemistry, the hydrogel electrolyte can effectively stabilize Zn anodes while simultaneously accelerating reaction kinetics. Consequently, the hydrogel electrolyte enables Zn-symmetric cells to exhibit excellent stability over a duration exceeding 2200 h at 1 mA cm –2, and Zn–MnO 2 full cells demonstrate enhanced rate capability and safety under various external damages. Overall, this work provides a reliable nature-inspired design strategy of hydrogel electrolytes toward high-performing ZIBs.