Electrophoretic Deposition of LiFePO4 Composite Cathodes on Carbon Fibres: Process Behaviour and Electrochemical Performance

Carbon-fibre-supported cathodes are components of multifunctional energy-storage composites, but their manufacture requires coating routes capable of depositing electrochemically active material directly onto fibrous substrates with controllable loading and process consistency. This work investigates the electrophoretic deposition (EPD) of LiFePO4/carbon-black/PVP composite cathodes onto carbon-fibre tow from an acetone-iodine suspension. Deposited areal mass was characterised across a 30–40 V and 5–10 min process window using three replicate depositions per condition. Mean coating loading ranged from 0.83 mg cm−2 at 30 V/5 min to 4.82 mg cm−2 at 40 V/10 min, while run-to-run variability was substantially greater at 40 V (52–61% coefficient of variation) than at 30 V (19–27%). Scanning electron microscopy showed successful particulate coating extending into the visible depth of the carbon-fibre tow without obvious large cracks or delamination at the examined magnification, while qualitative EDS mapping showed co-localised Fe, P, and O signals and a distributed N signal consistent with the PVP-containing coating. Electrochemical performance was demonstrated in a Li half-cell and in full-cell configurations employing graphite and carbon-fibre negative electrodes, illustrating that the EPD-manufactured cathode is electrochemically active, although further optimisation is required to improve the accessible performance. Overall, the study establishes a direct EPD route for manufacturing electrochemically functional, particle-coated carbon-fibre electrodes and identifies process consistency and cell integration as key considerations for their further development in multifunctional structural-battery architectures.