Energy storage of thermally reduced graphene oxide

The energy-storage capacity of reduced graphene oxide (rGO) is investigated in this study. The rGO used here was prepared by thermal annealing under a nitrogen atmosphere at various temperatures (300, 400, 500 and 600 °C). We measured high-pressure H2 isotherms at 77 K and the electrochemical performance of four rGO samples as anode materials in Li-ion batteries (LIBs). A maximum H2 storage capacity of ∼5.0 wt% and a reversible charge/discharge capacity of 1220 mAh/g at a current density of 30 mA/g were achieved with rGO annealed at 400 °C with a pore size of approximately 6.7 Å. Thus, an optimal pore size exists for hydrogen and lithium storage, which is similar to the optimum interlayer distance (6.5 Å) of graphene oxide for hydrogen storage applications. [Display omitted] •The optimum pore size of rGO for both Li and H2 storage exists at ∼6.7 Å.•The rGO was prepared by thermal annealing at temperatures ranging from 300 to 600 °C.•A reversible capacity of 1220 mAh/g at 30 mA/g was achieved with the rGO400.•The maximum H2 uptake of ∼5.0 wt% at 77 K is also obtained with the rGO400.•It is because an optimal pore size exists for hydrogen and lithium storage.