Capacity Contribution Mechanism of rGO for SnO2/rGO Composite as Anode of Lithium-ion Batteries

Abstract

Compared with ordinary graphite anode, SnO2 possesses higher theoretical specific capacity, rich raw materials and low price. While the severe volume expansion of SnO2 during lithium-ion extraction/intercalation limits its further application. To solve this problem, in this work the reduced graphene oxide (rGO) was introduced as volume buffer matrix of SnO2. Herein, SnO2/rGO composite is obtained through one-step hydrothermal method. Three-dimensional structure of rGO could effectively hinder the polymerization of SnO2 nanoparticles and provide more lithium storage sites attributed to high specific surface area and density defects. The initial discharge capacity of the composite cathode is 959 mA·h·g-1 and the capacity remained at 300 mA·h·g-1 after 1000 cycles at 1 C. It proved that the rGO added in the anode has a capacity contribution to the lithium-ion battery. It changes the capacity contribution mechanism from diffusion process dominance to surface driven capacitive contribution. Due to the addition of rGO, the anode material gains stable structure and great conductivity.