J.M. Pappas, X. Dong
Arizona State University,
United States
Keywords: additive manufacturing, structural electrodes, continuous carbon fiber, pyrolysis, carbon fiber-reinforced carbon, hard carbon, sodium-ion batteries
Summary:
Structural electrodes are of interest for use in structural batteries to simultaneously carry load and store energy, and are thus capable of significant system level mass and volume reductions over separate battery and structural components. The ability to 3D print carbon fiber-reinforced carbon structural electrodes in arbitrary geometries would not only allow for flexible battery design, but also enable fabrication of complex lattice structures which have been shown to significantly improve areal capacities over monolithic electrodes and enhance ion transport through microchannels. Lattice structures have potential to increase energy storage capability of structural batteries by enabling the use of thick electrodes, while simultaneously increasing strength and load bearing capability due to carbon fiber reinforcement of the electrode. In this work, carbon fiber-reinforced carbon structural electrodes were investigated by first 3D printing continuous carbon fiber composites with fiber placement deposition and ultraviolet curing. Inexpensive photopolymer was used as the resin matrix, which was subsequently carbonized to form hard carbon via pyrolysis, rendering the carbon fiber-reinforced carbon electrodes which retain the printed structure morphology to a high degree. Hard carbon is readily suitable for intercalation of sodium ions and thus the fabricated electrodes were directly used for fabrication and electrochemical characterization of sodium ion batteries. Compositional and microstructural analysis provided valuable insights into the electrochemical performance of the printed electrodes for use in sodium ion batteries, while characterization of mechanical properties demonstrated the feasibility of fabricating functional structural battery composites.