Kinetics‐Boosted Effect Enabled by Zwitterionic Hydrogel Electrolyte for Highly Reversible Zinc Anode in Zinc‐Ion Hybrid Micro‐Supercapacitors

Abstract Despite impressive merits of complementary charge‐storage mechanisms for aqueous Zn‐ion hybrid micro‐supercapacitors (ZHMSCs), it remains a challenge to solve dendrite and parasitic reactions issues of Zn anodes. Herein, a kinetics‐boosted strategy of Zn 2+ transport and desolvation of hydrated Zn 2+ is proposed by engineering zwitterionic P(AM‐ co ‐SBMA) hydrogel electrolyte (PASHE) for highly reversible Zn plating/stripping. Mechanically robust and chemically anchored PASHE features zwitterionic groups for constructing ion migration channels and immobilizing water molecules, which accelerates Zn 2+ migration for an ultrahigh transfer number (0.84) and alleviates water‐related parasitic reactions. Theoretical calculations combined with experimental results reveal that sulfobetaine sulfonate anions endow PASHE with improved desolvation kinetics and the ability to coordinate Zn 2+ flux and electric field distributions at the electrolyte–electrode interface. Thus, Zn anodes exhibit excellent electrochemical performance involving high average coulombic efficiency of 99.4% in Zn|PASHE|Cu cell as well as high cumulative capacity of 2000 mAh cm −2 (20 mA cm −2 , 1 mAh cm −2 ) and depth of discharge of 80.9% (20 mA cm −2 , 10 mAh cm −2 ) in Zn|PASHE|Zn cells. Furthermore, ZHMSCs based on PASHE deliver excellent flexibility and cyclability for energy‐storage applications. This work provides useful insights on hydrogel electrolyte engineering for developing high‐performance Zn anodes and derived energy‐storage devices.