Electro-chemo-mechanical couplings in structural batteries with diffusion, migration and convection in the electrolyte
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The structural battery is essentially a carbon fiber reinforced polymer-based composite, which has the ability to store electrical energy (i.e. work as a battery) and, simultaneously, carry mechanical loads. The carbon fibers can function as combined active electrode material, current collector, and mechanical reinforcement. They are embedded in a Structural Battery Electrolyte (SBE) [1] which consists of two phases: a solid phase (a porous polymer network) and a liquid electrolyte that serves as the carrier of ions, most importantly Li-ions. The ion-mobility is then brought about by stress-assisted diffusion (driven by the gradient of the chemical potential), migration (from the electric field) and convection from fluid motion (seepage velocity). In summary, the liquid phase in the porous polymer network enables ion transport between the electrodes, while the solid phase distributes mechanical stresses. In this presentation, we demonstrate the capability of a recently developed computational modeling framework [2] for evaluating the coupled electro-chemo-mechanical properties of structural batteries. In particular, we focus on the contribution from the stress-assisted convection in the SBE and the influence of the SBE porosity on the combined electro-chemical and mechanical performance. This effect is more pronounced in a structural battery than in a conventional one due its function as a structural composite. In fact, this effect is normally ignored in the context of conventional battery analysis.
