Synergistic effect of Na enrichment and F modification on copper Prussian blue analogue nanoparticles for supercapacitors

Prussian blue analogues (PBAs) are promising energy storage materials for supercapacitors. However, high defects and low activity are challenging for high-performance of PBAs. Herein, we propose a series of modified copper Prussian blue analogues (CFPs) with interface rearrangement followed by F modification and Na enrichment. The spectroscopic and electrochemical characteristics demonstrated the synergistic effect of F and Na, revealing the advantages of efficient electronic control and reaction sites synergism, which contributes to the high ion/electron transport and reversibility of CFPs. Benefitting from the reduced defects, optimized conductivity, and boosted electrochemically active surface and exposed active sites resulting from pre-stored Na and regulated F, the supercapacitor performance of CFP-3 has been improved, with a specific capacity of 182 F g⁻¹ at 1 A g⁻¹, and the rate capability is 82.4 % of the initial specific capacitance at 10 A g⁻¹, which is 4 times higher than that of unmodified CFP-0. Asymmetric CFP-3//CNT device achieves an energy density of 6.1 Wh kg⁻¹ at a power density of 1 kW kg⁻¹, and an energy density of 5.3 Wh kg⁻¹ at a power density of 7 kW kg⁻¹. After 10,000 cycles, the device still retains 82.4 %, showing good cyclic stability. This work proposes a new approach to improve the energy storage properties by rearranging the interfacial atomic and optimizing the electrochemically active sites, which provides a new guidance for designing high-performance supercapacitor materials.