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

Abstract

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.