Simulation of deformation in a porous structural battery electrolyte: The effect on the electrochemical properties

Abstract

There is a great demand nowadays for a sustainable environment. Structural batteries are an innovative solution which can bear mechanical and electrical loads at the same time. They are multifunctional materials capable to provide electric energy and mechanical support. Integration of structural batteries in the transportation section will be beneficiary leading to a more carbon neutral economy. Two structural battery architectures have been proposed. A laminated half cell setup was implemented in the current analysis. The structure consists of two electrodes, the separator and the structural battery electrolyte (SBE). Lithium metal and carbon fibre (CF) were used as negative and positive electrode respectively. The SBE is a microporous polymer matrix, which consists of solid polymer network and liquid electrolyte trapped in the cavities. This microstructure is responsible for the multifunctional performance of the SBE which allow lithium ions to transport through the liquid phase whereas the solid area provide mechanical support. One cycle of lithiation was computed in the current thesis work. During lithiation, lithium ions intercalate in the microstructure of the carbon fibre leading to the fibre’s expansion. This swelling compresses the surrounded SBE and affects its properties. Pores are closing due to the compression and the ion conductivity is decreasing over time. In order to model the response of the SBE and CF linear elasticity is used. Also, linear relation between porosity and volumetric strains, which occurred in the SBE, domain was implemented. The results indicate that there is a strong relation between porosity and ion conductivity. Further, experimental work is necessary for validation of the simulations.