High-performance supercapacitors from composites derived from recycled alkaline batteries

In this study, carbon–manganese dioxide (MnO2) composites were synthesized using carbon recovered from spent alkaline batteries through a simple wet-chemical process conducted at room temperature. The resulting materials were thoroughly characterized using XRD, Raman spectroscopy, FTIR, SEM, and electrochemical techniques. The composites exhibited a well-defined structure and outstanding electrochemical performance. Specifically, the 0.01 M MnO2 composite delivered a high specific capacitance of 215.46 F g− 1 at a current density of 1 A g− 1 in 0.25 M NaCl electrolyte and retained 91.3% of its capacitance after 2000 charge-discharge cycles - significantly outperforming pristine carbon (66.23% retention). Density Functional Theory (DFT) calculations confirmed that charge transfer from carbon to MnO2 enhanced the composite’s electrical conductivity and contributed to lattice stability. This research not only demonstrates a promising approach to recycling spent batteries but also offers a cost-effective and eco-friendly strategy for developing high-performance supercapacitor electrode materials.