Beneficial Effects of a Li Salt on Electrode Behavior in an Ionic Liquid for Electric Double Layer Capacitors

抄録

Origins of cathodic stability of an ionic liquid electrolyte, 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIBF₄) containing lithium tetrafluoroborate (LiBF₄), are investigated mainly by applying electrochemical impedance spectroscopy for a glassy-carbon electrode interface. Its Helmholtz layer capacitance in the EMIBF₄ electrolyte containing Li⁺ becomes much higher than that in neat EMIBF₄ with increasing cathodic polarization. On the basis of such analyses as well as our hypotheses, a reasonable mechanism for the stabilizing effect induced by the Li salt addition is discussed.