Bimetallic Cobalt-Nickel Selenide Nanocubes Embedded in a Nitrogen-Doped Carbon Matrix as an Excellent Li-Ion Battery Anode

Lithium-ion batteries (LIBs) have been widely used forportableelectronics and electric vehicles; however, the low capacity in thegraphite anode limits the improvement of energy density. Transition-metalselenides are promising anode material candidates due to their hightheoretical capacity and controllable structure. In this study, wesuccessfully synthesize a bimetallic transition-metal selenide nanocubecomposite, which is well embedded in a nitrogen-doped carbon matrix(denoted as CoNiSe2/NC). This material shows a high capacityand excellent cycling for Li-ion storage. Specifically, the reversiblecapacity approaches & SIM;1245 mA h g(-1) at 0.1A g(-1). When cycled at 1 A g(-1),the capacity still remains at 642.9 mA h g(-1) evenafter 1000 cycles. In-operando XRD tests have been carried out toinvestigate the lithium storage mechanism. We discover that the outstandingperformance is due to the unique CoNiSe2/NC nanocompositecharacteristics, such as the synergistic effect of bimetallic selenideon lithium storage, the small particle size, and the stable and conductivecarbon structure. Therefore, this morphology structure not only reducesthe volume change of metal selenides but also produces more lithiumstorage active sites and shortens lithium diffusion paths, which resultsin high capacity, good rate, and long cycling.