Conductive Network Confinement Effect Suppresses PBAs Agglomeration for Superior Supercapacitor Performance

Abstract

Prussian blue analogues (PBAs) are promising electrode materials for supercapacitors, owing to their three-dimensional open framework, tunable composition, abundant redox active sites, and facile synthesis. However, their practical application is hindered by intrinsic poor electrical conductivity and structural degradation during cycling, leading to rapid capacity fading and inferior stability. To address these challenges, this study constructs a three-dimensional conductive network using low-cost coal-based porous carbon (PC). Through a combined solvothermal-calcination approach, a composite material (PBAs@PC-10–500) was synthesized. This highly conductive PC network not only dramatically enhances the overall electrical conductivity but also effectively disperses the PBAs nanoparticles, thereby mitigating their agglomeration during long-term cycling. Consequently, the composite electrode exhibits significantly improved electrochemical performance. At a current density of 1 A g–1, the PBAs@PC-10–500 electrode delivers a high specific capacitance of 960 F g–1, which is approximately 2.8 times that of the pristine PBAs-500 (346.4 F g–1). Remarkably, it maintains 69.6% of its initial capacitance when the current density is increased 30-fold. Furthermore, an asymmetric supercapacitor assembled with this composite material was tested in both 6 M KOH electrolyte and KOH/PVA gel electrolyte. When operating at a power density of 800 W kg–1, the asymmetric device delivered an energy density of 24.58 Wh kg–1 in 6 M KOH and 35.57 Wh kg–1 in PVA/KOH gel electrolyte. The capacitance retention rate remained as high as 95.9% after 10,000 charge–discharge cycles at a current density of 10 A g–1 in 6 M KOH electrolyte, demonstrating excellent long-term cycling stability.