Effects of state of charge on elastic properties of 3D structural battery composites

Abstract

The effects of state of charge (SOC) on the elastic properties of 3D structural battery composites are studied. An analytical model based on micromechanical models is developed to estimate the effective elastic properties of 3D structural battery composite laminae at different SOC. A parametric study is performed to evaluate how different design parameters such as volume fraction of active materials, stiffness of constituents, type of positive electrode material, etc. affect the moduli of the composite lamina for extremes in SOC. Critical parameters and configurations resulting in large variations in elastic properties due to change in SOC are identified. As the extreme cases are of primary interest in structural design, the effective elastic properties are only estimated for the electrochemical states corresponding to discharged (SOC=0) and fully charged (SOC=1) battery. The change in SOC is simulated by varying the volume and elastic properties of the constituents based on data from literature. Parametric finite element (FE) models for square and hexagonal fibre packing arrangements are also analysed in the commercial FE software COMSOL and used to validate the analytical model. The present study shows that the transverse elastic properties ‫ܧ‬ ଶ and ‫ܩ‬ ଶଷ and the in-plane shear modulus ‫ܩ‬ ଵଶ are strongly affected by the SOC while the

Thermal and diffusion induced stresses in a structural battery under galvanostatic cycling

“…In earlier work by the authors [21] the state of charge was shown to have a significant effect on the elastic properties of this type of material. In that study, only extremes in SOC were considered and thermal effects were neglected.…”

“…The objective of this paper is to study the internal stresses in a 3D structural battery composite caused by heat generation and volume change of constituents under galvanostatic cycling (constant current charge/discharge cycles). A semi-analytical framework has been developed to predict the internal stresses based on a concentric cylinder (CC) model [20,21].…”

“…The polymer matrix is assumed to be made of a bi-continuous polymer network developed by Ihrner et al [11] reinforced with LiFePO 4 and carbon black particles. In the current analysis a baseline configuration of the composite lamina is defined based on previous work done by the authors [21,24]…”

“…where ܸ ୮ * is the volume fraction of particles in the matrix and ‫ܭ‬ ୮ and ‫ܭ‬ ୫ are the bulk moduli of the particles and matrix, respectively. The effective bulk modulus of the particle reinforced matrix ‫ܭ‬ ୫,ୣ is derived as explained in [21] based on work by Hashin [38]. The…”

Structural battery composites: a review

“…Carlstedt et al (2019b) developed an analytical model to investigate how the elastic properties of the 3D-fibre structural battery composite are affected by changes in volume and stiffness of the constituents associated with a change in SOC. Carlstedt et al (2019b) present results from a parametric study performed to analyse how different design parameters such as volume fraction of active materials, stiffness of constituents, type of positive electrode material, etc affect the moduli of the structural battery composite for extremes in SOC. Indeed, the composite's transverse elastic properties E T and G TT and the in-plane shear modulus G LT were found to be highly affected by the SOC for critical configurations, while the longitudinal stiffness E L was not.…”