Mussel-inspired, hydrophobic association-regulated hydrogel electrolytes with super-adhesive and self-healing properties for durable and flexible zinc-ion batteries

Abstract

Quasi-solid-state gel polymer electrolytes (GPEs) can overcome the limitations of aqueous electrolytes and offer unparalleled adaptability which is critical to flexible aqueous Zn-ion batteries (AZIBs) for wearable electronics. However, the notorious Zn dendrites and inevitable interface delamination between electrodes and GPEs under mechanical deformation cause serious capacity fading or failure in AZIBs. Herein, highly adherable, strong, and self-healable GPEs constructed with physically crosslinked dopamine grafted sodium alginate and hydrophobic association network are designed to suppress Zn dendrite formation, reduce interfacial detachment, and maintain the electrochemical performance of flexible AZIBs during serious mechanical manipulations. The resulting GPE demonstrates outstanding attributes including high mechanical strength (382 kPa), good interfacial adhesion (80 kPa), exceptional ionic conductivity (32.3 mS cm−1), and desired self-healing efficiency (72.4 % after 5th breaking-healing cycle). Consequently, the assembled Zn//Zn cells achieve an improved cycling lifespan of over 2000 h at 2.0 mA cm−2. The assembled Zn//MnO2 batteries exhibit a high specific capacity of 290 mA h g−1 at 0.2 A g−1 and ultrahigh capacity retention of 91 % after 4000 cycles at 4 A g−1. Moreover, these flexible batteries maintain excellent performance under dynamic bending, twisting, and compressing, as well as remarkable reliability and self-healing ability, which are imperatively significant for practical applications.