Additive Manufacture of Graphene Electrodes for Supercapacitor Applications

Electrochemical energy storage devices, such as supercapacitors, are essential contributors to the implementation of sustainable energy. Supercapacitors exhibit fast charging/discharging ability and have attracted considerable attention within the automotive, aerospace, and telecommunication industries. Although these devices show great potential to meet power density metrics, they lack in terms of their energy density. To overcome this challenge, we are investigating better materials, architectures, and additive manufacturing techniques to print electrodes that increase the energy density while maintaining their high-power densities. Topology optimization was used to design an electrode with optimum performance. These electrodes were printed by projection micro stereolithography (PµSL) using PR48, a commercially available polymer resin. The printed electrodes were converted to carbon electrodes through pyrolysis at 1050 ֯C and characterized by cyclic voltammetry (CV), galvanostatic charge/discharge (GCD), and electrical impedance spectroscopy. The performance of the PR48 optimized electrodes were compared against PR48 electrodes printed as a simple cubic lattice structure previously shown to improve capacitance and rate capability. The results show that our optimized electrodes have higher areal capacitances for all the current densities tested and they perform better in GCD and CV tests. Lastly, to increase the surface area of the electrodes and increase the capacitance further, we developed a resin formulation by combining graphene oxide (GO) into TMPTA polymer. Electrodes printed with 3%GO/TMPTA have improved electrochemical performance compared to PR48 as evidenced by their higher capacitances and their better GCD and CV curves. This work demonstrates the benefits of using topology optimization to design electrodes and materials development to improve the functional properties of 3D printable resins. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344. Lawrence Livermore National Security, LLC Figure 1