Prussian blue analogues (PBAs) have been highlighted as electrode materials for aqueous rechargeable batteries (ARBs) because of their favorable crystal structure and electrochemical activity. However, dissolution of the transition-metal ions during cycling degrades the materials and hinders the development of long-life-span batteries. To overcome this limitation, a strategy to revive the capacity degradation of PBA-based cathodes was developed herein based on designing all-PBA-based core@shell materials, while specific reduction upon introducing the shell layers was minimized. The core@shell materials were constructed using a V/Fe PBA (high capacity) core and a Cu/Fe PBA (high cycling stability) shell via a two-step co-precipitation method. The electrochemical performances including specific capacity, cycling stability, and rate capability as a function of the Cu/Fe PBA shell thickness were explored. At the optimal Cu/Fe PBA thickness, improved capacity retention after 200 cycles of >90% (72% for the core only) was attained with negligible capacity reductions from 94 (core only) to 90 (core@shell) mA h g–1, arising from the high electrochemical activity and stability of the Cu/Fe PBA shell and stabilized interfaces due to the crystallographic coherence between the core and shell materials. In addition, the power performance of the core@shell materials was significantly improved, e.g., C38.4C/C0.6C for a core@shell of 80% and core only of 62%, arising from the unique chemical coordination and facile ion diffusion kinetics of the Cu/Fe PBA shell. The newly developed V/Fe@Cu/Fe PBA-based cathodes offer an effective strategy for fabricating sustainable and low-cost ARBs.

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