Electrochemically Exfoliated Graphene Additive-Free Inks for 3D Printing Customizable Monolithic Integrated Micro-Supercapacitors on a Large Scale.

Three-dimensional (3D) printing technology with enhanced fidelity can achieve multiple functionalities and boost electrochemical performance of customizable planar micro-supercapacitors (MSCs), however, precise structural control of additive-free graphene-based macro-assembly electrode for monolithic integrated MSCs (MIMSCs) remains challenging. Here, the large-scale 3D printing fabrication of customizable planar MIMSCs is reported utilizing additive-free, high-quality electrochemically exfoliated graphene inks, which is not required the conventional cryogenic assistance during the printing process and any post-processing reduction. The resulting MSCs reveal an extremely small engineering footprint of 0.025 cm 2 , exceptionally high areal capacitance of 4900 mF cm -2 , volumetric capacitance of 195.6 F cm -3 , areal energy density of 2.1 mWh cm -2 , and unprecedented volumetric energy density of 23 mWh cm -3 for a single cell, surpassing most previously reported 3D printed MSCs. The 3D printed MIMSC pack is further demonstrated, with the maximum areal cell count density of 16 cell cm -2 , the highest output voltage of 192.5 V and the largest output voltage per unit area of 56 V cm -2 up to date are achieved. This work presents an innovative solution for processing high-performance additive-free graphene ink and realizing the large-scale production of 3D printed MIMSCs for planar energy storage.