Conversion of hydroperoxoantimonate coated graphenes to Sb ₂S₃@graphene for a superior lithium battery anode

We describe a method for conformal coating of reduced graphene oxide (rGO) by stibnite nanocrystallites. First, graphene oxide (GO) supported amorphous hydroperoxoantimonate was produced using the recently introduced hydrogen peroxide synthesis route. Sulfurization of the amorphous antimonate yielded supported antimony(V) oxide nanoparticles and sulfur, which were then converted by high temperature vacuum treatment to 15-20 nm rGO supported stibnite. The usefulness of the new material and synthesis approach are demonstrated by highly efficient and stable lithium battery anodes. Since both sulfur lithiation and antimony-lithium alloying are reversible, they both contribute to the charge capacity, which exceeded 720 mA h g^-1 after 50 cycles at a current density of 250 mA g^-1. The very small crystallite size of the stibnite provides a minimum diffusion pathway and allows for excellent capacity retention at a high rate (>480 mA h g^-1 at 2000 mA g^-1 was observed). The nanoscale dimensions of the crystallites minimize lithiation-induced deformations and the associated capacity fading upon repeated charge-discharge cycles. The flexibility and conductivity of the rGO ensure minimal ohmic drop and prevent crack formation upon repeated cycles.