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

Metal oxide (MO_x)-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 MO_x-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 MO_x-based anode materials using nanoperforated graphene with improved reversibility of the conversion reaction for Li-ion batteries.