Nanohybridization of CoS /MoS Heterostructure with Polyoxometalate on Functionalized Reduced Graphene Oxide for High-Performance LIBs.

To address the poor cycling stability and low rate capability of MoS as electrode materials for lithium-ion batteries (LIBs), herein, the CoS /MoS /PDDA-rGO/PMo nanocomposites are constructed via a simple hydrothermal process, combining the advantages of all three, namely, CoS /MoS 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 MoS , meanwhile stabilize the negatively charged [PMo O ] . After the electrochemical testing, the resulting CoS /MoS /PDDA-rGO/PMo nanocomposite achieved 1055 mA h g initial specific capacities and stabilized at 740 mA h g after 150 cycles at 100 mA g current density. And the specific capacities of MoS , MoS /PDDA-rGO, CoS /MoS , and CoS /MoS /PDDA-rGO were 201, 421, 518, and 589 at 100 mA g after 150 cycles, respectively. The fact of the greatly improving capacity of MoS -based nanocomposites suggests its potential for high performance electrode materials of LIBs. Moreover, the lithium storage mechanism of CoS /MoS /PDDA-rGO/PMo has been discussed on the basis of cyclic voltammetry with different scan rates.