Development and Characterization of Structural Batteries

The structural battery (see figure) is a modern battery concept that integrates mechanical strength and conductive properties of carbon fibres, that hence constitute an intimate part of both electrodes [1]. The core components in a structural battery are composites, developed to provide multiple functions. The structural electrolyte, for instance, needs to both transfer load and conduct ions, whilst a glass fibre reinforced fabric acts as a separator between the electrodes. Good chemical and morphological properties are also crucial at the electrolyte/fiber interface. Similarly to more mature and commercially available batteries, currently tested structural batteries also rely on the conduction of Li ions. It is crucial to realise that highly functional structural batteries can revolutionise the lightweight design of many transport modes. However, such progression requires composite materials able to provide ionic conductivities above 10 -4 S/cm and, simultaneously, good mechanical properties, targeting strength higher than 300 MPa and an elastic modulus over 70 GPa. Unfortunately, materials with exactly this set of properties do not exist yet and their development is the focus of our research. In this presentation, I will share recent progress done on the development of structural batteries, emphasising on the results that we have recently obtained from measurements by dielectric spectroscopy, NMR diffusometry, Raman spectroscopy and differential scanning calorimetry [2]. In particular, I will demonstrate the successful integration of protic ionic liquids into the concept of structural battery electrolytes and show the enhancement of local dynamics as an effect of nano-confinement. I will also show results on tests done by battery cycling and on dielectric spectroscopy measurements by which we were able to catch both ionic and electronic conduction. [1] Leif E. Asp et al. ; Structural battery composites: a review; Functional Composites and Structures 1 (2019) [2] A. Pipertzis, et al.; Ion transport, mechanical properties and relaxation dynamics in structural battery electrolytes consisting of an imidazolium protic ionic liquid confined into a methacrylate polymer. Energy Materials 300050 (2023) Figure 1