Unlocking the potential of SnS(2): Transition metal catalyzed utilization of reversible conversion and alloying reactions

The alloying-dealloying reactions of SnS(2) proceeds with the initial conversion reaction of SnS(2) with lithium that produces Li(2)S. Unfortunately, due to the electrochemical inactivity of Li(2)S, the conversion reaction of SnS(2) is irreversible, which significantly limit its potential applications in lithium-ion batteries. Herein, a systematic understanding of transition metal molybdenum (Mo) as a catalyst in SnS(2) anode is presented. It is found that Mo catalyst is able to efficiently promote the reversible conversion of Sn to SnS(2). This leads to the utilization of both conversion and alloying reactions in SnS(2) that greatly increases lithium storage capability of SnS(2). Mo catalyst is introduced in the form of MoS(2) grown directly onto self-assembled vertical SnS(2) nanosheets that anchors on three-dimensional graphene (3DG) creating a hierarchal nanostructured named as SnS(2)/MoS(2)/3DG. The catalytic effect results in a significantly enhanced electrochemical properties of SnS(2)/MoS(2)/3DG; a high initial Coulombic efficiency (81.5%) and high discharge capacities of 960.5 and 495.6 mA h g(−1) at current densities of 50 and 1000 mA g(−1), respectively. Post cycling investigations using ex situ TEM and XPS analysis verifies the successful conversion reaction of SnS(2) mediated by Mo. The successful integration of catalyst on alloying type metal sulfide anode creates a new avenue towards high energy density lithium anodes.