Leif Asp's KTH Solid Mechanics KEYNOTE seminar "Coupled electro-chemo-mechanical processes in structural battery composite materials"

Lei_Asp 2026_09_10.pdf (pdf 306 kB)

Abstract. Structural battery composites utilise carbon fibres in their electrodes. In the negative electrode, often referred to as the anode, carbon fibres distributed in a structural electrolyte act as active electrode material, i.e., host of lithium, current collector, and reinforcement. In the positive electrode carbon fibres coated with a lithium iron phosphate (LFP) rich coating embedded in a structural electrolyte constitute a structural cathode. Here, the carbon fibres in the positive electrode acts as scaffold for the LFP, current collector and reinforcement. The two electrodes are separated by a thin cellulose fabric. During charging following a red-ox reaction at the fibre / structural electrolyte interface lithium enters into the carbonaceous structure of the fibre. As the lithium inserts and coordinates with the carbon atoms, the fibre expands approximately 1 % along its axis and 7 % in the radial direction. This volume change causes extensions of the composite ply, i.e., the electrode, that must be considered in the laminate design. In addition, the elastic moduli of the carbon fibre vary with state of lithiation, where the modulus in the transversely isotropic plane doubles for the fully lithiated carbon fibre compared to the pristine or delithated one. At the same time, the longitudinal modulus is reduced by 12 %. These volume changes and change in elastic moduli of the fibres affect the internal mechanical stresses in the carbon fibre electrode. In this talk, the influence of state of lithiation on the multifunctional performance of the negative structural battery full cell will be discussed. Furthermore, the coupled electro-chemo-mechanical processes will be discussed and an example of the effects of mechanical stresses on the electrical potential of the structural battery will be reviewed.