Highly concentrated graphene oxide ink for facile 3D printing of supercapacitors

3D printing of functional energy storage devices is receiving escalating attention over the years due to the customizable manufacturing flexibility and imparted high areal and gravimetric energy density of three-dimensional structured devices, which contribute to the creation of numerous new opportunities for futuristic electronics. Graphene-based inks are ideal elements for the realization of 3D printed energy storage devices if the attractive intrinsic physiochemical properties of graphene could be preserved. However, it is still a great challenge to prepare uniformly dispersed graphene-based materials with desired rheological properties for 3D printing. Here we report a facile strategy for 3D printing of supercapacitors from a highly concentrated graphene oxide (GO) ink. The GO is properly dispersed and the ink fulfills the stringent rheological specifications for 3D printing. The printed GO electrode is functionalized with enhanced structural stability for proper reduction to graphene. The printed supercapacitors deliver the potential to linearly scale up in areal capacitance without jeopardizing the gravimetric capacitance when increasing printed layers. The results hold great promise for the construction of 3D structured energy storage devices that cater to the challenges from next-generation electronics.