Tin-indium/graphene with enhanced initial coulombic efficiency and rate performance for lithium ion batteries

Tin is an attractive anode material replacing the current commercial graphite for the next generation lithium ion batteries because of its high theoretical storage capacity and energy density. However, poor capacity retention caused by large volume changes during cycling, and low rate capability frustrate its practical application. In this study, a new ternary composite based on tin-indium alloy (Sn-In) and graphene nanosheet (GNS) was prepared via a facile solvothermal synthesis followed by thermal treatment in hydrogen and argon at 550 degrees C. Characterizations show that the tin-indium nanoparticles with about 100 nm in size were wrapped between the graphene nanosheets. As an anode for lithium ion batteries, the Sn-In/GNS composite exhibits a remarkably improved electrochemical performance in terms of lithium storage capacity (865.6 mAh g(-1) at 100 mA g(-1) rate), initial coulombic efficiency (78.6%), cycling stability (83.9% capacity retention after 50 cycles), and rate capability (493.2 mAh g(-1) at 600 mA g(-1) rate after 25 cycles) compared to Sn/GNS and Sn-In electrode. This improvement is attributed to the introduction of lithium activity metal, indium, which reduces the charge transfer resistance of electrode, and the graphene nanosheet which accommodates the volume change of tin-indium nanoparticles during cycling and improves electrical conductivity of material. (C) 2013 Elsevier B. V. All rights reserved.