Redox Mediator–assisted Electrochemical Behaviour of Mn2P2O7 Nanoclusters for Symmetric Supercapacitors

The increasing need for efficient and sustainable energy storage solutions has driven extensive research into advanced electrode materials for electrochemical capacitors. Developing high-performance electrode material is a key challenge in the design of sustainable electrochemical capacitors. Among various candidates, manganese pyrophosphate (Mn₂P₂O₇) is a promising one due to its redox activity and cost-effective synthesis. However, its limited specific capacitance and poor cycling stability restrict its practical implementation. This study seeks to improve electrochemical performance of Mn₂P₂O₇ nanoclusters (MPncs) by integrating a redox mediator (RM) into the electrolyte. MPncs were synthesized via a hydrothermal method and subsequently characterized in both KOH and RM-assisted KOH electrolytes to evaluate their electrochemical performance. In pure KOH electrolyte, MPncs electrode achieves a specific capacity of 650 C/g at 1 A/g, with 80 % capacity retention over 10,000 cycles. The incorporation of RM into KOH electrolyte enhances electrochemical performances substantially, reaching a higher specific capacity of 1250 C/g at 1 A/g while maintaining 95 % capacity retention over equivalent cycling.RM also improves rate capabilities, redox behavior, and charge transfer kinetics. Additionally, the MPncs −based symmetric supercapacitor shows an impressive capacity of 380 C/g at 1 A/g and an energy density of 73.8 Wh/Kg at a power density of 700 W/Kg, alongside exceptional cycling stability (94 % of retention over 5000 cycles).These results highlight the RM effectiveness in overcoming intrinsic limitation of Mn₂P₂O_7, offering a viable strategy for developing advanced electrode materials. This study advances the development of high-performance supercapacitors for next generation energy storage applications.