Mesoporous Co3O4 rugby balls were firstly obtained by utilizing a facile two-step method. This unique morphology together with the mesoporous feature manifests excellent capacitive performance an energy density (14.3 W h kg−1), a power density (7503 W kg−1) and no decay after 10 000 cycles for constructing the Co3O4 rugby balls//graphene hydrogels asymmetric supercapacitor.
