Analysis of a shape morphing structural battery: manufacturing, analytical modeling and numerical simulation

Sammanfattning: A reduction in the global use of fossil fuels is necessary when striving for a more sustainable future. One key strategy in the transition from fossil fuels is electrification. This strategy is particularly prominent within the transport sector, where more efficient ways to store electric energy are being pursued. Structural battery composites represent a promising technology. Being based on multifunctional composite materials that can carry mechanical loads and store electrical energy at the same time, they provide a ‘mass-less’ energy storage. This work aims to develop a shape morphing structural battery capable of bending upwards and downwards in a cantilever setup. The structural battery is made from several constituents. Two outer layers of carbon fibers act as negative electrodes and a middle layer of aluminium foil coated with NMC622 on both sides acts as the positive electrodes. Additionally, a glass veil layer and a ceramic separator separate the positive and negative electrodes. A structural battery electrolyte is used to embed the laminate in order to provide load transfer and ion transfer. From this setup, it is possible to control the lithiation/delithiation of each carbon fiber layer independently and thereby bend the laminate in the desired direction. Subsequently, the system is modeled both analytically using Matlab and numerically using Comsol Multiphysics 6.1.  From the models it is found that the system is in theory capable of large deformations, showing promising results. However, the experimental laminates show low capacity upon cycling which would cause near to zero deformations. The poor performance of the system could be linked to incompatibility between the structural battery electrolyte and the NMC622.