Synthesis of CuFe-PBA@NiFe-PBA nanocubes as a battery electrode for Na-ion hybrid supercapacitor

Prussian blue analogues (PBAs) have been proposed as electrode materials for energy storage systems, offering potential advantages in terms of cost-effectiveness, extended lifespan, and high energy output. However, bimetallic positive electrode materials with high capacity suffer from a significant drawback: inadequate cycle stability. In this work, a core-shell CuFe-PBA@NiFe-PBA material was designed using a straightforward coprecipitation method, wherein high-capacity CuFe-PBA are encapsulated within a reliable shell NiFe-PBA. The electrochemical performance of CuFe-PBA@NiFe-PBA has demonstrated effectiveness in mitigating Cu-ion dissolution during charging and discharging processes. CuFe-PBA@NiFe-PBA delivered a specific capacitance of 567 F/g and maintained a cycle stability of 73.0 % after 10,000 charge/discharge cycles. Furthermore, CuFe-PBA@NiFe-PBA was utilized as a positive electrode in the assembly of a hybrid device, achieving an impressive energy density of 48.17 Wh/kg at a power density of 1022.5 kW/kg, while still maintaining an optimal energy density of 38.9 Wh/kg even at a high power density of approximately 10 kW/kg. and cycle stability of 93.1 % after 10,000 charge discharge cycles. The impressive performance of the hybrid device highlights its versatility and efficiency, positioning it as a compelling contender in the field of energy storage devices.