▎ 摘　　要

We demonstrate a facile synthesis of ultrafine SnO2 nanoparticles within graphene nanosheets (GNSs) via thermal decomposition of tinoctoate, in which tin-octoate is firstly blended with GNSs followed by annealing in air at a low temperature (350 degrees C) and a short time (1 h). As anode for lithium ion batteries, the SnO2/GNSs displays superior cycle and rate performance, delivering reversible capacities of 803 and 682 mA h/g at current densities of 200 and 500 mA/g after 120 cycles, respectively, much higher than that of pure SnO2 and GNSs counterparts (143 and 310 mA h/g at 500 mA/g after 120 cycles, respectively). The enhanced electrochemical performance is attributed to the ultrafine SnO2 nanoparticle size and introduction of GNSs. GNSs prevent the aggregation of the ultrafine SnO2 nanoparticles, which alleviate the stress and also provide more electrochemically active sites for lithium insertion and extraction. Moreover, GNSs with large specific surface area (similar to 363 m(2)/g) act as a good electrical conductor which greatly improves the electrode conductivity and also an excellent buffer matrix to tolerate the severe volume changes originated from the Li-Sn alloying-dealloying. This work provides a straightforward synthetic approach for the design of novel composite anode materials with superior electrochemical performance.