Synergistic optimization of ion kinetics and stability via gradient interphase engineering for high-performance aqueous Zn-ion batteries

Aqueous zinc-ion batteries (AZIBs) feature high safety, environmental compatibility, and low cost, being regarded as a promising candidate for sustainable energy storage. However, random spatial distribution of interfacial components deteriorates transport kinetics and interfacial stability, severely constrains the development of AZIBs. To address the issues, we herein introduce Carbomer 940 (CB) as a crosslinker for polyvinylidene fluoride (PVDF), forming a hybrid binder with enhanced viscosity, electronic conductivity, and ionic migration. Crucially, the binder enables gradient component distribution within interfacial film, achieving the collaborative enhancement of ion diffusion kinetics and electrode cycling stability. As a result, these cells using optimized hybrid binder exhibit the lifespan up to 1000 and 40,000 cycles with discharge capacity of 259.4 and 52.3 mAh·g^–1 at 1 and 10 A·g^–1, respectively. Furthermore, the hybrid binder further demonstrates its universality in lithium-ion and sodium-ion batteries. Therefore, the gradient interfacial design provides a synchronous solution for realizing long-cycle-life rechargeable batteries.