Formation of yolk-shell Co-Mn Prussian blue analog spheres with enhanced electrochemical performance for supercapacitors

Supercapacitors (SCs) represent a specialized category of capacitors distinguished by their high power density, rapid charge-discharge capability, long lifespan, and broad operational temperature range. Prussian blue (PB) and PB analogs (PBAs) are frequently employed as electrode materials in SCs. Still, considerable capacitance degradation and inadequate Na+ diffusion kinetics considerably hinder the large-scale applications of PBAs. Consequently, herein, the efficient self-template strategy and anionic exchange method are used to synthesize yolk-shell structured PBA microspheres with an Mn:Co ratio of 5:1 (MnCo-PBA YSS). In a neutral electrolyte, MnCo-PBA YSS exhibits commendable electrochemical performance, achieving a specific capacitance of 280.0 F g- 1 at a current density of 1 A g- 1 and a capacitance retention of 70.1 % after 5500 charge-discharge cycles. A two-electrode system configured using MnCo-PBA YSS as the positive electrode and commercially available YP-50F as the negative electrode exhibits a specific capacitance of 28.3 F g- 1 at 0.5 A g- 1. The remarkable electrochemical properties of MnCo-PBA YSS are attributed to the presence of internal voids, a shell composed of small nanoparticles, a high specific surface area, a low coordination water content, and minimized charge transfer resistance. These results indicate that MnCo-PBA YSS holds promise as a potential positive electrode material for SCs.