| 초록 |
Prussian blue analogues (PBAs) have potential advantages of a favorable crystallographic structure and high electro-chemical activity as aqueous rechargeable battery (ARB) cathodes; however, dissolution of the transition-metal ions in PBA structure causes capacity degradation and inhibits the development of long-life batteries. Herein, we developed a vanadium hexacyanoferrate@copper hexacyanoferrate (V/Fe@Cu/Fe PBA) with all-PBA-based core@shell structure. The cathode material composed a V/Fe PBA core with high capacity and a Cu/Fe PBA shell with high cycling stability were synthesized using a simple two-step co-precipitation method. To identify the change of electrochemical performance depending on the relative composition of the core and shell, the thickness of shell was systematically controlled by adjusting the concentration of precursor for Cu/Fe PBA shell. At the optimal shell thickness, a capacity retention after 200 cycles was improved up to 90% (core only: 72%) and an initial capacity reduction was minimized with negligible reductions from 94 (core only) to 90 mA h g−1 (core@shell). In addition, the rate capability of the core@shell materials was remarkably improved (e.g., C38.4C/C0.6C: core@shell of 80% and core only of 62%). These results originated from the high electro-chemical activity, cycling stability, unique chemical coordination, and facile ion diffusion kinetics of the Cu/Fe PBA shell and stabilized interfaces caused by crystallographic coherence between the core and shell materials. The V/Fe@Cu/Fe PBA-based cathode will provide an effective strategy for fabricating sustainable and low-cost ARBs. |
