Nanohybridization of CoS₂ /MoS₂ Heterostructure with Polyoxometalate on Functionalized Reduced Graphene Oxide for...

To address the poor cycling stability and low rate capability of MoS₂ as electrode materials for lithium-ion batteries (LIBs), herein, the CoS₂ /MoS₂ /PDDA-rGO/PMo₁₂ nanocomposites are constructed via a simple hydrothermal process, combining the advantages of all three, namely, CoS₂ /MoS₂ heterojunction and polyoxometalates (POMs) provide abundant catalytically active sites and increase the multi-electron transfer ability, and the positively charged poly(diallyldimethylammonium chloride) modified reduced graphene oxide (PDDA-rGO) improve electronic conductivity and effectively prevent the aggregation of MoS₂ , meanwhile stabilize the negatively charged [PMo₁₂ O₄₀ ]^3- . After the electrochemical testing, the resulting CoS₂ /MoS₂ /PDDA-rGO/PMo₁₂ nanocomposite achieved 1055 mA h g^-1 initial specific capacities and stabilized at 740 mA h g^-1 after 150 cycles at 100 mA g^-1 current density. And the specific capacities of MoS₂ , MoS₂ /PDDA-rGO, CoS₂ /MoS₂ , and CoS₂ /MoS₂ /PDDA-rGO were 201, 421, 518, and 589 at 100 mA g^-1 after 150 cycles, respectively. The fact of the greatly improving capacity of MoS₂ -based nanocomposites suggests its potential for high performance electrode materials of LIBs. Moreover, the lithium storage mechanism of CoS₂ /MoS₂ /PDDA-rGO/PMo₁₂ has been discussed on the basis of cyclic voltammetry with different scan rates.