Kinetically enhanced electrochemical redox reactions by chemical bridging SnO2 and graphene sponges toward high-rate and long-cycle lithium ion battery

Graphene has been widely used to improve the electrochemical performance in rate and cycling stability for SnO2. However, the mechanism of the synergistic effect and the interfacial interaction between SnO2 and graphene are still not fully understood. Herein, we put forward a novel, cost effective strategy to construct hierarchical SnO2 nanoclusters anchored on the graphene sponges for lithium storage by in situ self assembly. The result shows that the synergistic effect and interfacial interaction origin form the existence of strong oxygen bridges between SnO2 and graphene via the COSn linkage. It is demonstrated for the first time that the interfacial interaction by COSn bonding plays a crucial role in the rate and cycling stability both experimentally and theoretically. Thus, the SnO2@graphene sponges exhibit remarkable rate capability (a reversible capability of 1141, 997, 912, 831, 693, 536, and 302 mA h g−1 at 0.2 C, 0.5 C, 1 C, 2 C, 5 C, 10 C and 20 C, respectively) and cycling performance (after 625 cycles at 6 A g−1 with a capacity retention of 537 mA h g−1).