Mac Geoffrey is a PhD student from the Department of Mechanical Engineering at the University of Bath and Cohort 3 member of EPSRC AAPS CDT.
His interest in signals and systems landed him a PhD position in 2022 focusing on ultrasonic non-destructive testing on multi-layered lithium-ion battery cells authorising continuous in-service charge and health monitoring.
In addition to his PhD, Mac Geoffrey covers a graduate teaching assistant position both in the fields of signal processing, signals, systems and communication, microprocessors and interfacing, and electromechanical design systems I and II designed for 1st and 2nd year undergraduates in the Department of Electronic and Electrical Engineering at the University of Bath.
With the increasing use of batteries in various industries, ensuring their safety and reliability has become critically important. While current methods, such as battery management systems, provide valuable functionality, there remain significant challenges in accurately measuring the State of Charge (SoC). Traditional approaches, including coulomb counting and open-circuit voltage (OCV) measurements, are prone to issues such as error accumulation over time or flat readings in certain operating conditions. These limitations underline the need for improved techniques that can provide more precise and reliable SoC estimations to support safer battery usage.
This research investigates the application of ultrasound as a non-invasive, cost-effective, and innovative tool for enhancing SoC estimation. The mechanical properties of the battery are probed using ultrasound measurements, such as Time of Flight (ToF) and signal amplitude (SA), which offer key information into the internal condition of the battery. The compact size of ultrasound transducers makes this method practical for use in confined environments, such as battery modules in electric vehicles, further increasing its applicability. The potential for ultrasound to complement existing SoC estimation methods demonstrates its promise as a tool for advancing battery safety and monitoring technologies.
Mac's study focuses on three key areas of investigation. First, it examines SoC inhomogeneities in lithium-polymer (LiPo) batteries through ultrasound immersion testing, analysing variations in wave speed and attenuation to identify structural defects or material inconsistencies. Second, it explores the aging behaviour of LiPo batteries, with an emphasis on uncovering unique features at low SoC levels that are not yet documented in the literature. Finally, the research extends to nickel-manganese-cobalt (NMC) batteries, comparing their aging characteristics to LiPo findings. It also evaluates ultrasound’s effectiveness in monitoring a module of three stacked batteries under various C-rates and temperatures, offering novel insights into module-level battery behaviour. Together, these efforts demonstrate the potential of ultrasound to enhance battery safety and improve performance monitoring leading to more reliable and efficient energy storage systems
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