Optimization of Capacitance Balance for a Hybrid Supercapacitor Consisted of LiMn 2 O 4 /AC as a Positive and AC Negative Electrode

Abstract

A hybrid supercapacitor is fabricated using a composite material from LiMn2O4 (LMO) and activated carbon (AC) as the pos. electrode and AC as the neg. electrode to form the (LMO + AC)/AC system. Vol. ratio (pos. : neg.) of electrodes is controlled to investigate of the power and energy balance. The (LMO + AC)/AC system shows better performances than the LMO/AC system. Esp., electrochem. impedance spectra, rate charge-discharge and cycle performance testing show that the (LMO + AC)/AC system have an outstanding electrochem. performance at vol. ratios of (LMO + AC)/AC = 1 : 1.7 and 1 : 2. Elec. double layer capacitor (EDLC) capacitance between AC of the pos. electrode and AC of the neg. electrode improves power d. without loss of capacitance. Stable capacitance is achieved by lowering the pos. electrode resistance and balancing the energy and power densities between the pos. and neg. electrodes by the addn. of AC to the pos. electrode at high c.d. [on SciFinder(R)]