Structural batteries are a class of structural power composites capable of storing electrochemical energy while simultaneously bearing mechanical load. This novel technologyoffers the potential for “massless” energy storage, in which the structural componentsof a vehicle or aircraft also function as the battery itself. These multifunctional systems may have the potential for significant benefits in energy efficiency, range, andweight reductions. However, to realise these advantages, an improved understandingof the coupled electro-chemo-mechanical behaviour of constituent materials and scalable methods for manufacturing integrated battery structures are required.This thesis has addressed these challenges through three interconnected research strands.The first part of the thesis investigated the multifunctionality of carbon fibre anodesusing in situ and in operando synchrotron X-ray diffraction. These studies establisheda direct link between lithium intercalation and atomic-scale expansion within the carbon fibre lattice. Interlayer spacing in the [002] direction expanded during lithiationand contracted upon delithiation, while in-plane expansion along [100] was smallerbut followed a similar trend. When mechanical tension was applied during charging,the [002] spacing contracted and only partially recovered upon unloading, revealing astrong coupling between electrochemical and mechanical responses.The second part focused on developing scalable electrode and separator coatings compatible with continuous fibre manufacturing. Electrophoretic deposition was shown toproduce broadly uniform LFP coatings on carbon fibres, and a reel-to-reel coating system was developed to demonstrate process scalability. Dynamically coated electrodesexhibited greater long-term stability and lower overpotentials than static coatings, despite slightly reduced capacity. Electropolymerisation was explored as a method forproducing thin, conformal separator coatings directly onto electrode surfaces. Thesecoatings maintained electrochemical functionality with minimal performance loss relative to uncoated fibres. Dual-layer electrodes were produced, that successfully demonstrated integrated functionality, though with increased resistance due to the separatorlayer. Additionally, the incorporation of a solid biphasic electrolyte achieved comparable electrochemical performance to liquid systems, suggesting promise for lightweight,solid-state structural battery configurations. Together, these results provide a clearpathway toward scalable, multifunctional manufacturing processes for structural battery components.ivThe final part of the thesis demonstrated a proof-of-concept full-cell, combining dynamically coated LFP cathodes with EP-coated carbon fibre anode–separator systems. Theassembled cells exhibited measurable electrochemical performance and revealed key insights into interfacial and separator behaviour. Notably, the presence of an effectivelydouble separator layer increased internal resistance and overpotential, underscoring thecrucial role of separator design in overall cell performance. Attempts to remove theglass fibre separator led to immediate short-circuiting, confirming that the EP coatingalone was not yet sufficient as a standalone separator. Nonetheless, achieving suchfunctionality would represent an exciting step toward fully intermingled, separator-freestructural battery architectures.
Investigation and quantification of multiphysics coupling phenomena present in novel structural battery architectures.
Rodriguez Santana, P. (Author). 24 Jun 2026
Student thesis: Doctoral Thesis › PhD