Appropriately hydrophilic/hydrophobic cathode enables high-performance aqueous zinc-ion batteries

Abstract Organic batteries with improved electrode wettability will exhibit a better electrochemical performance. How about the relationship between electrode wettability and battery performance in aqueous batteries? Here the effect of cathode wettability in aqueous zinc-ion batteries (AZIBs) on the zinc-ion diffusion and charge transfer based on a research platform of cellulose nanowhiskers (CNWs)/graphene/MnO2 wire-in-scroll nanowires with water contact angles turning from 64.70 ± 3.72° to 115.85 ± 3.36° as cathodes for AZIBs has been investigated, where the corresponding battery performance shows a parabola trend with the peak in 103.04 ± 2.91°. The cathode achieves a high capacity of 384 mAh g−1 at 1 C and features an ultra-long lifetime of over 5000 cycles at 20 C, representing excellent Zn storage performance. A combination of experimental measurements and density functional theory calculations suggests that increased cathode hydrophobicity forces hydrated Zn2+ desolvation at electrode-electrolyte interface, facilitating zinc-ion insertion into host materials, yet extremely hydrophobic cathode leads to sluggish electrochemical kinetics. This study opens a new idea in the design of promising candidates for developing low cost and long lifespan batteries for aqueous systems.