Study of capacitive properties for LT-Li4Mn5O12 in hybrid supercapacitor

Spinel Li4Mn5O12 nanoparticles have been prepared by a very simple sol-gel method. Various initial conditions were studied in order to find the optimal conditions for the synthesis of pure Li4Mn5O12. X-ray diffraction results showed that spinel Li4Mn5O12 was obtained at a low temperature of 300 A degrees C without any miscellaneous phase. Scanning electron microscope analyses indicated that the prepared Li4Mn5O12 powders had a uniform morphology with average particle size of about 50 and 100 nm. The prepared sample was firstly used as a cathode material in an asymmetric Li4Mn5O12/AC supercapacitor in aqueous electrolyte. The capacitive properties of the hybrid supercapacitor were tested by cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge-discharge tests. The results showed that Li4Mn5O12 annealed at 450 A degrees C for 4 h exhibited the best electrochemical capacitive performance within the potential range of 0-1.4 V in 1 M Li2SO4 solution. A maximum specific capacitance of 43 F g(-1) based on the total active material weight of the two electrodes was obtained for the Li4Mn5O12/AC supercapacitor at a current density of 100 mA g(-1). The capacitor showed excellent cycling performance and structure stability via 1,000 cycles.