Multifunctional Additive Manufacturing and Multiphysics Numerical Investigations of Carbon Fiber Structural Battery Composite using a Drop-on-Demand method with In-situ Consolidation

Abstract

Lightweight carbon fiber structural battery composite has great potential in increasing structural energy storage efficiency for multifunctional applications. However, it is still challenging to design carbon fiber multifunctional composite due to lack of proper manufacturing methods. In this study, an integrated multifunctional design and fabrication approach is developed by combining a drop-on-demand additive manufacturing method with a multiphysics numerical model to guide the development of the new multifunctional composite. Through deposition with in-situ consolidation, the function and thickness of each carbon fiber layer as well as its fiber volume fraction are accurately controlled. Decreasing layer thickness improves flexural properties. The discharge capacity and energy density are initially improved by 47% and 39%, respectively, but then significantly reduced due to limited lithium transport within closely packed carbon fibers at higher volume fraction. An optimal fiber volume fraction of 35 vol% exists for carbon fiber structural battery composite. A good agreement is found between prediction results and experimental measurements. Further investigations of lithium-ion concentration and stress distribution by the validated multiphysics model find that electrolyte conductivity more significantly affects discharge process than discharge rate. The multifunctional design and fabrication approach provides insights for future development of high-performance carbon fiber structural battery composite.