Unveiling the Potential of Natural Deep Eutectic Solvents in Electrochemical Energy Storage Applications

Supercapacitors are
key to sustainable energy storage
due to their
high power density and long lifespan, though their energy density
remains limited. This study explores natural deep eutectic solvents
(NADES) as alternative electrolytes for graphene-based supercapacitors
via molecular dynamics simulations. Three NADEScomposed of
betaine chloride and the amino acids arginine, histidine, or lysineare
assessed for their biocompatibility, cost-effectiveness, and hydrogen-bonding
capabilities. Simulations at 300 and 600 K reveal distinct physicochemical
behaviors: histidine-based NADES shows the highest density and cohesive
energy, attributed to imidazole-mediated interactions, while lysine-based
NADES offers the greatest ionic mobility. In supercapacitor models,
asymmetric electric double layers (EDLs) form, with amino acids dominating
the positive EDL and betaine the negative. Interaction energy analyses
underscore the stabilizing role of amino acids in the EDL structure.
Capacitance values range from 2.2 to 2.8 μF/cm2,
aligning with those of conventional electrolytes. These results highlight
the promise of NADES as sustainable and tunable electrolytes, offering
a viable route to enhance the performance of next-generation supercapacitors.