Controllable etching construction of nickel-based Prussian blue analog nanocages for stabilized energy storage in aqueous nickel-zinc batteries

A key new insight from the study is that ammonia complex etching—an unusual method that avoids non-selective dissolution of traditional etching—successfully creates nickel-cobalt Prussian blue analog nanocages (NC-NiCo-PBA) with octahedral cavities, solving long-standing issues of nickel-based cathodes in aqueous nickel-zinc batteries (NZBs).

Traditional NZB cathodes suffer from particle fragmentation and capacity loss due to lattice stress and slow ion diffusion.  However, the NC-NiCo-PBA retains an intact PBA skeleton, boosts specific surface area to 151.38 m²g⁻¹, shortens ion transfer distance, and eases volume strain.  This improves NZB performance: the NC-NiCo-PBA//Zn battery hits 0.33 mWh cm⁻² energy density and 25.86 mW cm⁻² power density.

A surprise was that etching didn’t alter elemental valence or crystal structure, ensuring stability. "This study provides a new‘topological regulation-kinetic optimization’approach for aqueous battery cathode design,” notes the team, shining light on how hollow nanostructures unlock better energy storage—advancing NZBs’ potential for large-scale, low-cost energy storage.