3D Printed Symmetric Carbon Supercapacitors: A Study Comparing Electrochemical Performance and Cycle Life Depending on 3D Printing Technique and Materials

With the ongoing global energy crisis, producing reliable and efficient methods of energy storage remains an integral part of cutting-edge materials research. Within this topic, 3D-printing (also known as additive manufacturing) is evolving from a niche hobby to a reliable scientific tool for materials science research 1-3. 3D-printing energy storage materials provides unparalleled levels of customisation 4-9 and freedom of design, while also eliminating waste material during the manufacturing process. 3D-printing energy storage materials has been widely covered, but usually just focuses on one method of 3D-printing. Directly comparing more than one 3D-printing method within a single energy storage study is far more seldom researched. This work directly compares the electrochemical performances of symmetric carbon-based supercapacitor devices made using two 3D-printing techniques, SLA (stereolithography) and FDM (fused deposition modelling). Two cell types are made in this study, one with gold-sputtered SLA-printed current collectors, the other with conductive PLA (polylactic acid) FDM-printed current collectors. Carbon-based electrode (various combinations of SWCNT, GNP, Super-P, PVDF) slurries and aqueous 6M KOH electrolyte are implemented in these cells. The benefits and limitations of these 3D-printing methods are directly compared, with the electrochemical performance of the supercapacitor cells being analysed using cyclic voltammetry and galvanostatic charge-discharge tests. The sputtered conductive SLA current collector cells display better conductivity and more ideal rectangular cyclic voltammetry curves for electronic double-layer capacitors (EDLCs) but suffer from poor cycle life in initial experiments (~5,000 charge-discharge cycles before losing all specific capacitance). The FDM current collector cells have poorer conductivity, less ideal cyclic voltammetry curves, and are less structurally sound (causing some electrolyte leakage over long term cycling) but offer extremely stable cycle life for supercapacitor cells, retaining most of their specific capacitance after 100,000 charge-discharge cycles. The cycle lives of the gold-sputtered SLA current collector cells are greatly improved after several changes made during the study, such as reducing the voltage window from 0.0-1.0 V to 0.2-0.7 V, and exploring additives for the carbon-based slurry electrodes, such as Super-P and PVDF (polyvinylidene fluoride). References 1 J. Li, M. Leu, R. Panat and J. Park, "A hybrid three-dimensionally structured electrode for lithium-ion batteries via 3D printing.," Materials & Design, vol. 119, pp. 417-424, 2017. 2 A. Ambrosi and M. Pumera, "3D-printing technologies for electrochemical applications.," Chemical society reviews, vol. 45, no. 10, pp. 2740-2755, 2016. 3 A. Maurel, M. Courty, B. Fleutot, H. Tortajada, K. Pdrashantha, M. Armand, S. Grugeon, S. Panier and L. Dupont, "Highly loaded graphite–polylactic acid composite-based filaments for lithium-ion battery three-dimensional printing.," Chemistry of Materials, vol. 30, no. 21, pp. 7484-7493, 2018. 4 V. Egorov and C. O'Dwyer, "Architected porous metals in electrochemical energy storage.," Current Opinion in Electrochemistry, vol. 21, pp. 201-208, 2020. 5 V. Egorov, U. Gulzar, Y. Zhang, S. Breen and C. O'Dwyer, "Evolution of 3D printing methods and materials for electrochemical energy storage.," Advanced Materials, vol. 32, no. 29, p. 2000556, 2020. 6 U. Gulzar, C. Glynn and C. O'Dwyer, "Additive manufacturing for energy storage: Methods, designs and material selection for customizable 3D printed batteries and supercapacitors.," Current Opinion in Electrochemistry, vol. 20, pp. 46-53, 2020. 7 B. Yao, S. Chandrasekaran, J. Zhang, W. Xiao, F. Qian, C. Zhu, E. Duoss, C. Spadaccini, M. Worsley and Y. Li, "Efficient 3D printed pseudocapacitive electrodes with ultrahigh MnO2 loading.," Joule, vol. 3, no. 2, pp. 459-470, 2019. 8 S. O'Hanlon and C. O'Dwyer, "Electrodeposition onto Conductive Additive-Impregnated 3D Printed Polylactic Acid Electrodes.," Journal of The Electrochemical Society, vol. 169, no. 8, p. 082514, 2022. 9 U. Gulzar, V. Egorov, Y. Zhang, and C. O’Dwyer, "Recyclable 3D-Printed Aqueous Lithium-Ion Battery", Adv. Energy Sustainability Res. 4, 2300029, 2023.