Synergistic effect of graphene nanoperforation on the reversibility of the conversion reaction of a SnO2/nanoperforated graphene composite

Abstract

Metal oxide (MOx)-based anodes suffer from large capacity loss and low Coulombic efficiency due to the irreversible formation of Li2O during the conversion reaction. Despite numerous studies addressing this issue, the development of MOx-based anode materials with high cycle reversibility remains a critical challenge. In this study, the reversibility of the conversion reaction of Sn and Li2O to SnO2 is significantly improved through the innovative design of a SnO2/nanoperforated graphene composite as an anode material. Nanoperforations are introduced at the contact points of SnO2 with graphene to increase the interfacial area of Sn/Li2O, which resulted in improved reversibility of the conversion reaction. Ex-situ high-resolution transmission electron microscopy imaging coupled with selected area electron diffraction pattern, ex-situ XRD and XPS analyses corroborate the improved reversibility of the conversion reaction. The specific charge capacity of SnO2 in the SnO2/nanoperforated graphene composite is 1446 mAh g−1 at the current density of 100 mA g−1, which is very close to the theoretical capacity of SnO2 (1494 mAh g−1 based on the fully reversible conversion reaction and alloying/de-alloying reaction). Furthermore, the maintenance of the initial differential capacity plots after 800 cycles demonstrates the improved reversibility of the conversion reaction of the SnO2/nanoperforated graphene composite over extended cycles. These results provide important insights into the rational design of MOx-based anode materials using nanoperforated graphene with improved reversibility of the conversion reaction for Li-ion batteries.