Effects of Fe Impurities on Self-Discharge Performance of Carbon-Based Supercapacitors

Activated carbon is widely used as an electrode material in supercapacitors due to its superior electrochemical stability, excellent electrical conductivity, and environmental friendliness. In this study, the self-discharge mechanisms of activated carbon electrodes loaded with different contents of Fe impurities (Fe and Fe3O4) were analyzed by multi-stage fitting to explore the tunability of self-discharge. It is was found that a small quantity of Fe impurities on carbon materials improves the self-discharge performance dominated by redox reaction, by adjusting the surface state and pore structure of carbon materials. As the content of Fe impurities increases, the voltage loss of activated carbon with the Fe impurity concentrations of 1.12 wt.% (AF-1.12) decreases by 37.9% of the original, which is attributable to the reduce of ohmic leakage and diffusion, and the increase in Faradic redox at the electrode/electrolyte interface. In summary, self-discharge performance of carbon-based supercapacitors can be adjusted via the surface state and pour structure, which provides insights for the future design of energy storage.

Automated summary

This study found that a small amount of Fe impurities on activated carbon electrodes can improve self-discharge performance by adjusting the surface state and pore structure. Additionally, as the Fe impurity content increases, the voltage loss decreases, attributed to reduced ohmic leakage and diffusion, and increased Faradic redox at the electrode/electrolyte interface. In conclusion, the self-discharge performance of carbon-based supercapacitors can be adjusted through surface state and pore structure, providing insights for future energy storage design.