Graphene decorated LiMn₂O₄ electrode material for hybrid type energy storage devices

Lithium-ion capacitors (LICs) are becoming useful owing to their high energy and power densities. LICs show enhance capacitance than electric double-layer capacitance (EDLC) and pseudocapacitors, due to their battery electrode material, which can operate over a higher voltage window. LiMn₂O₄ is fast emerging electrode material for energy storage devices. The major limitation associated with it is the low conductivity. Therefore, to simultaneously improve the electrical conductivity as well as the electrochemical performance, a novel strategy of decoration LiMn₂O₄ with graphene is being proposed. Graphene will improve electrical conductivity while contributing to EDLC and pseudocapacitance values. A cost-effective synthesis protocol is utilized to obtain conical pyramid-type particles. These particles were thoroughly characterized using a large number of experimental techniques. Cyclic voltammetry and charge-discharge measurements were used to evaluate the electrochemical characteristics, in 0.0 to 1.2 V stable window, using 1M LiOH electrolyte. Graphene decorated LiMn₂O₄ electrode show improved cyclic stability and higher specific capacitances 250 F/g in comparison to LiMn₂O₄ electrode. The cycling stability of the electrode was above 90% up to 3000 cycles at a higher current density.