New transparent materials for applications as supercapacitors: Manganese-lithium-borate glasses

Abstract

The transparent manganese-lithium borate glasses were successfully prepared by melt-quench technique. The effect of the Mn content in the glasses on structure-function was characterized by conventional techniques e.g. XRD, SEM, TEM, XPS, UV–Vis and VSM. The vitreous samples exhibit pseudo capacitive behavior with the redox couple of the Mn2+/Mn3+ proofed by advanced synchrotron-based X-ray absorption spectroscopy (XAS) technique. The cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) were used to study the electrochemical properties of the prepared electrodes in 6 MKOH electrolyte. Interestingly, the increasing of Mn content from 20 mol% to 30 mol% can improve (∼2 time) their specific capacitance, energy density and capacity retention. The 0.3MnO2-0.7(Li2O-2B2O3) electrode exhibits the highest values of the specific capacitance (187.05 F g−1 for CV and 169.66 F g−1 for GCD), specific energy density (19.34 Wh kg−1) and capacity retention (76.05%) after 1000 cycles. This attributed to decreasing of electrolyte resistance and increasing of Mn2+ on the glass surface. Therefore, the results assured that manganese-lithium borate glasses have a great potential for development as electrode materials in supercapacitor applications.