Expeditious and eco-friendly synthesis of spinel LiMn2O4 and its potential for fabrication of supercapacitors

Spinel LiMn2O4 has been gaining more attention for supercapacitor applications due to its abundance, low cost, environmental friendliness, and high energy density as well as good rate capability. In this work nanostructured multimetal oxide LiMn2O4 was synthesized using expeditious, eco-friendly, glucose mediated simple microwave irradiation method. A detailed study has been performed to correlate the phase structure, surface morphology, redox reaction at the electroactive species and its potential impact on the electrochemical performance as the electrode material. The synthesized spinel LiMn2O4 electrode exhibits a good specific capacitance of 276 F g(-1) and 220 F g(-1) in aqueous (KOH) and non-aqueous (LiClO4/ethylene carbonate (EC)) electrolytes respectively at a scan rate of 20 mV s(-1). In aqueous electrolyte, the reaction kinetics of supercapacitors became very fast which is responsible for the exhibited high capacitance. Excellent capacitance retention of 90% even after 2000 cycles was achieved for this spinel structure. This indicates that the aqueous electrolyte and unique spinel structure are favourable for superfast redox kinetics of the prepared LiMn2O4 due to its higher ionic conductivity and electrochemical stability. (c) 2020 Elsevier B.V. All rights reserved.