Influence of Porosity Tuning in Magnesium Citrate‑Derived Carbon Composites on Electrochemical Supercapacitor Performance

Abstract

The growth in energy demand and the instability of renewable sources necessitate the development of effective energy storage systems. Supercapacitors are promising devices due to their high power, fast charging and discharging, and long cycle life. This paper investigates the structural and electrochemical properties of templated carbons produced from the carbonization of magnesium citrate and its composites with polyvinyl alcohol (PVA). It has been established that carbon from pure magnesium citrate is characterized by a developed porous structure with a specific surface area of 1706 m2/g and a microporous volume of 0.624 cm3/g. The addition of PVA leads to a decrease in specific surface area (to 514 m2/g at 66% PVA) and a fine tuning of the degree of structural order, which is confirmed by Raman spectroscopy data. Electrochemical tests in a two-electrode cell using 5 M NaNO3 showed a maximum specific capacitance of 128 F/g for carbon derived from pure magnesium citrate at 1.6 V. Composite materials demonstrate lower capacitance but maintain high Coulombic efficiency (>95%) within the tested voltage windows. These results indicate that the incorporation of PVA reduces both the accessible surface area and the electrochemical performance compared with pure magnesium citrate derived carbon, while confirming the promise of magnesium citrate as an affordable precursor for the production of porous carbon materials for supercapacitors.