Synthesis and Investigation of Nano LiMn2O4-rGO as a Positive Electrode inEnergy Storage Systems

Supercapacitors (SCs) deliver high power density but low energy density [1]. One way forincreasing the energy density of a SC is improving the efficiency of charge storage that isaffected by the electrode materials [2]. Mn-based oxides such as LiMn2O4 (LMO), haveeconomic and environmental advantages and excellent electrochemical performance as attractivepositive electrode materials in aqueous-electrolyte supercapacitors [3,4]. The performance ofSCs can be improved via shortening the ionic diffusion length and providing large surface areasfor electrode reactions and the easiness of electron transfer. In this regard, the nanosize materialsand composites of high conductive compounds such as reduced Graphene Oxide (rGO) [1,5,6]play the main role. In this work, we have synthesized nano LMO oxides and LMO-rGOcomposites by a simple, low temperature and fast hydrothermal method. Thus, these materialshave been investigated as positive electrode materials by CV, chrono-potentiommetry, and EIS.After optimization of the ratio of the composite components, that is LMO: GO ratio of 40:60% aspositive electrode material, the composite was characterized with different techniques includingXRD, Raman, EDX, SEM and TEM as well as BET and TGA analyses. The LMO-rGO electrodeshows a wide potential window of 1.1 V in Li2SO4 aqueous electrolyte. The specific capacitanceof the composite electrode at 1 A/g is 215 F/g, which shows superiority over an LMO electrode,130 F/g. The 65% increase in capacitance of the material shows a synergistic effect of rGO onelectrochemical performance of the LMO electrode.

کلیدواژه ها:

LiMn2O4 ، Graphene ، Supercapacitor ، Hydrothermal synthesis ، Energy Storage