In this presentation, we report the fabrication of free-standing graphene-based paper electrodes with controlled pore structures for high-performance Li–O₂ battery cathodes. Firstly, graphene nanoplatelet/graphene oxide (GNP/GO) papers were fabricated using a vacuum-assisted filtration method. The obtained GNP/GP paper electrodes had a highly wrinkled and disordered morphology and were highly flexible, which was attributed to the partial re-aggregation of the GNPs under the holding effect of the GOs during a drying process. Subsequently, the GNP/GO paper could be directly used as a Li–O₂ battery cathode without any conducting additives and polymeric binders. The GNP/GO paper electrode showed a much higher discharge capacity (6910 mAh/g at a current density of 200 mA/g) in comparison to the reduced-GO paper and commercially available carbon papers due to its higher Brunauer–Emmett–Teller (BET) surface area and pore volume. However, the GNP/GO paper electrode suffered from huge irreversible volume expansion during discharge due to the formation of relatively large Li₂O₂ inside the pores. This irreversible volume expansion of the electrode made a Li–O₂cell incapable in few cycles (< 20 cycles).

Secondly, in order to solve the volume expansion problem of the electrode, graphene papers with macropores within the paper that can accommodate relatively large discharge product were fabricated by using polystyrene particles as sacrificial templates. The as-prepared macroporous graphene paper (mp-GP) had a large BET surface area (ca. 373 m²/g), a large pore volume (ca. 10.9 cm³/g), and a high porosity (91.6%). Owing to the high surface area and large pore volume, a Li–O₂ cell using the mp-GP electrode exhibited a high discharge capacity of ca. 12,200 mAh/g at a current density of 200 mA/g, as well as good rate capability. Moreover, the mp-GP showed good stability up to 100 and 78 cycles at a current density of 500 mA/g and 2000 mA/g respectively, with a limiting capacity of 1000 mAh/g. It was found that formation and decomposition of the discharge product, Li₂O₂, occured within the macropores, and thus, the mp-GP maintained its original structure without considerable expansion during cycling.