High-performance Li–Se battery: Li2Se cathode as intercalation product of electrochemical in situ reduction of multilayer graphene-embedded 2D-MoSe2

Lithium–selenium (Li–Se) batteries are considered as promising candidates for next-generation battery technologies, as they have high energy density and low cost. A new class of electrochemical intercalation of interlayer MoSe₂ to graphene (Gr) Li₂Se based cathode materials for room temperature Li–Se batteries is reported. An advanced approach preparing spatially confined Li₂Se cathode active materials inside carbon materials to minimize the shuttle effects of Se compounds is confirmed by XRD, XPS, TEM and electrochemical analysis studies. The starting chalcogenide Gr–MoSe₂ were synthesized by applying a closed reflux system in diethylene glycol solvent, polypropylviologen as a carbon (C) precursor source, and selenoacetamide were used as Se precursor and followed by calcination under the Ar and N₂ atmosphere to form Gr- layers between MoSe₂ interlayers. Then, Mo in Gr–MoSe₂ nanocomposites are electrochemically reduced (lithiation process) to give multi-layered graphene structures, and selenide compounds, Li₂Se is generated inside graphene multi-layers, simultaneously in Li-Se battery. The capacity decay rate of the cell is 0.04% per cycle for 100 cycles, with nearly 100% coulombic efficiency throughout the cycling at current density of 1 Ag⁻¹. Nyquist plots, were reported for electrochemical impedance Gr–MoSe₂ as active materials after pretreatment step of 2 cycles (0.01–3 V) at 3 V and 0.01 V vs Li⁺/Li. Based on the conductivity of Gr–MoSe₂ characteristics, reporting here also a new class of cathode of Li₂Se, there is no conductive additive of carbon black to the active material.