Material thermal extrusion of conductive 3D electrodes using highly loaded graphene and graphite colloidal feedstock

Evolution in the energy storage field requires the development of more sustainable and efficient high-performance electrochemical storage devices (EESDs). Additive manufacturing (AM) opens unique opportunities to improve the efficiency and the electrochemical response by the design of 3D electrodes and the increasing of exposed active surface area impossible to achieve by other processing techniques. In other to reach high-performance EESDs, carbonaceous species are well-established as electroactive materials owing to their electronic properties, low cost, and sustainable origin. Although the materials have been widely investigated, there is a lack of feedstock development for the fabrication of EESDs by AM technologies. This work presents the fabrication of metals free light conductive filaments for material thermal extrusion (MTE) by formulating PLA-based composites with a high content of colloidal graphite and graphene (15–25 vol%). By the colloidal characterization and surface modification of the carbonaceous species, an improved distribution and enhanced platelet/polymer bond were achieved, provoking the inorganic phase's orientation during the extrusion process. Prepared filaments were characterized to analyze the influence of the microstructural anisotropy on thermal, thermorheological, mechanical, and electrical properties. Subsequently, developed filaments were used to print complex electrodes by MTE, enhancing the electrochemical properties of the electrodes with superior control of the macrostructural design. The developed colloidal filaments with an oriented inorganic microstructure, not only allow a defined shaping of the outer structure of the electrodes but also let the design of completely different microstructures. Consequently, different microstructural configurations were printed increasing the number of conduction paths in the polymeric matrix to achieve high electric conductivities (22 S.m-1) in printed electrodes.