Engineering the Li Storage Properties of Graphene Anodes: Defect Evolution and Pore Structure Regulation

A general and mild strategy for fabricating defect-enriched graphene mesh (GM) and its application toward the anode of Li-ion batteries (LIBs) has been reported. The GM with a pore size of 60-200 nm is achieved by employing Fe₂O₃ as the etching reagent that is capable of locally etching the graphene basal plane in a relatively mild manner. Upon different drying technologies, that is, oven drying and freeze-drying, GMs with different porous structure are obtained. The electrochemical Li storage properties of GMs in comparison with graphene aerogels (GAs) disclose that both defect sites and porous structure are crucial for the final anodic performances. We show that only when merged with rich porosity, the GM anode can achieve a better Li storage performance than that of GA. Moreover, we further fabricated nitrogen-doped GM (NGM) using urea as the nitrogen source with a freeze-drying process. Benefiting from the unique structural characteristics, that is, plentiful defects, abundant pores, and nitrogen doping, the NGM anode exhibits high Li storage capacity with good cyclic stability (1078 mAh g^-1 even after 350 continuous cycles at a current density of 0.2 C) and outstanding rate capability. Our finding provides fundamental insights into the influence of defects and pore structure on the Li storage properties of graphene, which might be helpful for designing advanced graphene-based anodes for LIBs.