Electro-induced interfacial enrichment polymerization enables flexible fiber zinc batteries with robust electrode-electrolyte interface and ultrahigh zinc utilization

Abstract Flexible aqueous fiber zinc batteries are recognized to be promising for flexible and wearable electronics due to both high safety and energy-storage capability. However, their applications have long been hindered by poor fiber electrode-gel electrolyte interfaces and extremely low zinc utilization. Here we report a highly controllable one-step electro-induced interfacial enrichment polymerization strategy to simultaneously address these challenges. The in-situ hybrid polymer hydrogel electrolyte is directly constructed on the fiber electrode surface via synchronously electro-initiated interfacial free-radical polymerization and ionic crosslinking. The rational interface design not only establishes exceptionally robust fiber electrode-gel electrolyte interfaces via strong interfacial chemical bonding, but also guides preferential deposition of Zn (002) plane and suppresses side reactions and dendrite growth. Consequently, even under an ultrahigh zinc utilization of 85.4%, the in-situ fiber Zn//Zn cells exhibit an extended cycling life exceeding 300 hours, significantly outperforming previously reported fiber Zn//Zn cells. Furthermore, at a low N/P ratio of 2.55, the highly flexible aqueous Zn//polyaniline fiber batteries demonstrate a high capacity retention of 92.31% after 1500 cycles with an average coulombic efficiency of 99.94%. This work presents a general and effective strategy to construct robust electrode-gel electrolyte interfaces for high-performance flexible and wearable energy storage devices.