Complementary surface modification by disordered carbon and reduced graphene oxide on SnO2 hollow spheres as an anode for Li-ion battery

Among the efforts to apply SnO2 as an anode, the adoption of carbonaceous materials has been considered as a decent strategy to mitigate volume expansion problem (similar to 300%) during cycling. Nevertheless, it still needs in-depth examinations to identify the individual role of each coating material and further improvements for practical applications. To understand the underlying correlations of various carbon coatings with electrochemical performance of active materials, disordered carbon and reduced graphene oxide (RGO) are selectively used for SnO2 hollow spheres. The disordered carbon, which covered the surfaces of and voids between the primary particles, acts as a buffer layer for volume expansion, and the RGO, that interconnected the hollow secondary particles, provides a 2D-electronic path to the electrode. Finally, both of them are utilized on the SnO2 hollow spheres, namely the double coating is conducted from the expectation of synergistic effects, and it successfully exhibits a moderate capacity after 100 cycles even at 1 C with a low carbon content (7.7 wt. %). The essential factors that are inherently present and thereby significantly affect the electrochemical performance of the SnO2 electrode are successfully identified by a facile dual-carbon modification, so that this strategy will be applicable to other potential active materials. (C) 2017 Elsevier Ltd. All rights reserved.