Water-Restrained Hydrogel Electrolytes with Repulsion-Driven Cationic Express Pathways for Durable Zinc-Ion Batteries
Dewu Lin, Yushuang Lin, Ruihong Pan, Jiapei Li, Anquan Zhu, Tian Zhang, Kai Liu, Dongyu Feng, Kunlun Liu, Yin Zhou, Chengkai Yang, Guo Hong, Wenjun Zhang
Abstract
Abstract The development of flexible zinc-ion batteries (ZIBs) faces a three-way trade-off among the ionic conductivity, Zn 2+ mobility, and the electrochemical stability of hydrogel electrolytes. To address this challenge, we designed a cationic hydrogel named PAPTMA to holistically improve the reversibility of ZIBs. The long cationic branch chains in the polymeric matrix construct express pathways for rapid Zn 2+ transport through an ionic repulsion mechanism, achieving simultaneously high Zn 2+ transference number (0.79) and high ionic conductivity (28.7 mS cm −1 ). Additionally, the reactivity of water in the PAPTMA hydrogels is significantly inhibited, thus possessing a strong resistance to parasitic reactions. Mechanical characterization further reveals the superior tensile and adhesion strength of PAPTMA. Leveraging these properties, symmetric batteries employing PAPTMA hydrogel deliver exceeding 6000 h of reversible cycling at 1 mA cm −2 and maintain stable operation for 1000 h with a discharge of depth of 71%. When applied in 4 × 4 cm 2 pouch cells with MnO 2 as the cathode material, the device demonstrates remarkable operational stability and mechanical robustness through 150 cycles. This work presents an eclectic strategy for designing advanced hydrogels that combine high ionic conductivity, enhanced Zn 2+ mobility, and strong resistance to parasitic reactions, paving the way for long-lasting flexible ZIBs.