Utilizing Manganese Phase Transition in Bioabsorption Synthesis of MnO@Carbon Composites for Enhanced High-Performance Supercapacitors

The bioabsorption method has emerged as an innovative approach for synthesizing electrode materials, offering dual benefits of environmental pollution control and energy problem resolution. Existing literature lacks comprehensive investigation into the correlation between metal phase transitions and electrochemical performance throughout the material preparation process using the bioabsorption method, encompassing changes in metal valence states, crystal structures, and redox reactions. This study aims to establish a direct link between manganese phase transitions and electrochemical energy storage. It elucidates the enrichment mechanism and phase transition process induced by manganese stress on organisms. By employing phase diagram calculations and high-temperature potassium hydroxide assistance, MnO single-phase-doped biomass carbon electrode materials are successfully synthesized, enabling precise control over metal crystal phase transitions. The redox reactions involved in manganese electrochemical storage are elucidated. Specifically, the material exhibits a high specific surface area of 1, 234.088 m2·g–1, a high degree of graphitization (ID/IG = 1.04), a specific capacitance of 498 F·g–1 at 0.5 A·g–1, and a capacity retention of 94% after 25,000 cycles. This work delves into the manganese phase transition process to enhance electrochemical performance, offering insights into the accumulation mechanisms and biological phase transition under heavy metal stress and providing a foundation for designing electrode materials assisted by phase diagrams.