(173c) Sn/SnOx /Graphene Nanocomposites: Synthesis and Anode Performance In Lithium- Ion Batteries

The utilization of a Sn/SnO_x/graphene nanocomposite as anode material for lithium-ion batteries could potentially provide high reversible capacity as well as a reduction of capacity fade upon cycling, by increasing the Sn:Li₂O ratio in the anode matrix. A two step chemical synthesis route has been developed to produce a Sn/SnO_x/Graphene nanocomposite. In the first step, SnO₂ nanoparticles were prepared by a hydrolysis method and loaded on graphene nanosheets using an ultrasonic treatment to make SnO₂/graphene nanocomposites. In the second step, Sn/SnOx/graphene was prepared by the partial reduction of SnO₂/graphene in a 10% H₂ in Ar mixture at 700 °C. To get nanosized Sn/SnOx particles with size in the range of 5-10 nm, reaction time and temperature were varied to control the nucleation and to obtain a homogeneous distribution of Sn nanoparticles on the graphene sheets, while pH of the solution was optimized, as at a specific pH the surface charge of the particles affects particle organization on the surface. The small size and uniform distribution of Sn/SnOx nanoparticles are designed to reduce the volume expansion of Sn during cycling. Hence, the anode of lithium-ion battery endures lower strain and is less likely to be cracked upon cycling. Sn:C ratios of 1.5, 2.5 and 3.5 in the Sn/SnOx/graphene nanocomposites will be evaluated for a superior Li-storage performance with good cycle life and high capacity.