Advancing Structural Batteries using Lithium-Iron Phosphate Functionalised High-Modulus Carbon Fibres Positive Electrodes

Abstract

This thesis explores the advancement of structural batteries by utilising nanosized lithium-iron phosphate functionalised high-modulus carbon fibres as positive electrodes. The innovative laminated structural battery architecture integrates active electrode materials with structural battery electrolyte, facilitating both mechanical load-bearing and ionic transport. We employed the electrophoretic deposition technique to coat CFs with a blend of nano-LFP, carbon black, and reduced graphene oxide in an ethanol suspension, enhanced by PDDA as a cationic polyelectrolyte. The study’s experimental phase optimised EPD parameters (70-80 V for 5-20 minutes), achieving uniform coatings with active material mass ranging between 12-35 mg. Electrochemical performance was evaluated through cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy. Halfcell results demonstrated that positive electrodes with nanosized LFP and highmodulus CFs exhibit promising potential for structural batteries, showing specific capacities and stable cycling behaviour. However, all-fibre full cells indicated the necessity for further research. The integration of CB and rGO significantly improved the electronic con ductivity and structural stability of the electrodes, contributing to enhanced overall battery efficiency. This work highlights the potential of functionalised high-modulus CFs in advancing the field of structural batteries, addressing both energy storage and mechanical integrity, crucial for future applications in electric vehicles and other weight-sensitive technologies.