A model to analyse deformations and stresses in structural batteries due to electrode expansions

In order to aid design of future structural battery components an analytical model is developed for modelling volume expansions in laminated structural batteries. Volume expansions are caused by lithium ion intercalation in carbon fibre electrodes. An extended version of Classical Lamination Plate Theory (CLPT) is used to allow analysis of unbalanced and unsymmetric lay-ups. The fibre intercalation expansions are treated analogously to a thermal problem, based on experimental data, with intercalation coefficients relating the fibre capacity linearly to its expansions. The model is validated using FEM and allows the study of the magnitude of interlaminar stresses and hence the risk of delamination damage due to the electrochemically induced expansions. It also enables global laminate deformations to be studied. This allows information about favourable lay-ups and fibre orientations that minimise deformations and the risk of delamination to be obtained. Favourable configurations for application to a solid state mechanical actuator are also given.