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As population and its energy demand increased, fossil fuels became a requirement for sustainment of daily life. However, their extended use has brought along several unwanted consequences that are now a subject of concern, for example global warming, increase to greenhouse gasses emissions, and changes to major meteorological events. Out of these concerns, the emergence of alternative energy devices, such as fuel cells, have attracted a significant amount of attention due to their superior efficiency and reduced dependency on fossil fuels. Out of the many fuel cells, solid oxide fuel cells (SOFC) are a specific type of fuel cell that operates at high temperatures (600 - 1000°C). Their inherently high operation temperatures broaden the spectra of potential fuel sources, and their excess heat can be integrated into other processes, further increasing the overall efficiency of the system. In recent years, SOFC technology has leaned towards reducing the operation temperature (600- 800°C). However, at lower temperatures the oxygen reduction reaction (ORR) kinetics become increasingly sluggish, challenging the use of traditional cathode materials, hence, the need for highly active cathodes, like LSCF-6428 (La0.6Sr0.4Co0.2Fe0.8 O3-δ). One of the major drawbacks of LSCF is its inherent tendency to degrade due to Sr-surface segregation (SSS), phenomena driven by elastic and electrostatic forces within the material structure that results in hindered ORR activity. Infiltration of a secondary phases has been reported to suppress SSS while enhancing ORR activity for Sr-containing electrodes. This work investigated Gd0.1Ce0.9O1.95 (GDC) and HfO2 at various concentrations as surface-modifiers on porous LSCF-6428 electrodes as well as dense substrates to evaluate their effect on electrode performance and SSS prevention when compared to unmodified LSCF when all materials are subjected to typical IT-SOFC operation conditions. It was observed from experimental results of unmodified electrodes that degradation rate for electrodes (dRp%) decreased for electrodes that were stored before testing (~31% and ~4%) in contrast to electrodes that were tested closer to their fabrication date (~60%). Additionally, SEM images showed the appearance of particles along the grain boundaries that grew with increasing ageing time, consistent with SSS in literature. The absence of SSS signs on the rest of the samples was theorised to be caused by a calendar ageing effect, that has yet to be reported in literature to the authors knowledge. When analysing surface-modified electrodes and substrates, it was observed that both surface modifications produced more stable, i.e. less degradable, and better performing electrodes as proved by EIS and Rp monitoring for 50h. GDC proved to be most effective when using 0.125M and 0.250M, while for HfO2 13.16 and 26.32 mg mL-1 concentrations worked best to produce electrodes with better ORR performance, this is lower Rp values, than non-infiltrated ones. Additionally, no surface particles that could be associated with SSS were identified using XRD nor SEM on flat substrates when surface modifications were used, suggesting that even the lowest concentrations were effective in preventing Sr-segregation. Although the previously identified calendar ageing effect on bare samples could also be identified on surface-modified measurements, it was ultimately concluded that due to time constraints and limitations, more research into this subject is necessary to elucidate the causes behind these observations.

The rapid growth in the adoption of lithium-ion batteries since their introduction in the 1990's is expected to continue in the coming years. Electric vehicles in particular will account for a large market share, being considered clean transportation technology compared to the internal combustion engine. Lithium-ion batteries change their internal state during cycles of charge and discharge. Estimation of the state of charge is commonly performed by battery management systems that rely on charge counting and cell voltage measurements. Determining the physical state of the battery components is challenging. Recently, the response of an ultrasonic pulse through a battery has been successfully correlated with both change in state of charge and state of health, the approach is now well established. This study assesses the qualities contained within an ultrasound signal response by investigating the behaviour of ultrasonic waves as they pass through the components in a layered battery structure, as those components change with battery charge. This is possible based on acoustic sensitivity to material property changes such as electrode density during charge cycling. Captured reflections from pulsed signals will accumulate in the signal response, with observed differences providing the potential for real-time, non-invasive, non-destructive measurements of internal changes in the battery cell. A model has been developed to understand the nature of the ultrasound response and the features that provide a particular characteristic. Modelling was based on the one-dimensional wave equation, scripted in MATLAB. Layered properties simulating a battery cell are required to run the model, the outputs of which include simulated wave responses, wave development plots and animations. Experiments were conducted to establish methodologies in detecting a relationship between battery state of charge and ultrasound response. Data analysis and visualisation methods were developed during this study to determine the optimal methods of gaining battery charge measurements. The accuracy of charge monitoring is affected by temperature, either from the cell or ambient conditions. Evaluation of temperature effect is possible using analysis contained in this work, with a method of calibrating signal for temperature suggested. It was concluded from experimental testing combined with modelling that small changes in battery parameters could cause significant changes to an expected signal response. The variety in cell construction and manufacturing discrepancies presents a serious problem for the application of ultrasound monitoring in practice. A smart peak selection method was developed to ensure that regardless of the nature of the ultrasound response, state of charge measurements are optimised by ensuring the regions of signal with best battery charge correlation are identified. This can greatly help with the automation of the process in a sensor-based battery management system. Finally, ultrasonic monitoring was explored as a method of early warning of the onset of thermal runaway during thermal abuse testing. The signal responses show deviations from expected signals at temperatures consistent with expected cell reactions to temperature increases, such as the onset of self-heating and electrode delamination. Instrumentation calibration and limitation tests were conducted to provide confidence that changes in ultrasound responses are battery and not sensor related.

Supplementation of monogastric animal feed with exogenous enzymes has become standard practice with many positive impacts observed in animals and the environment. Recently there has arisen a need to investigate the effects that anti-nutrients, specifically those found in sorghum grain, might have on the activity of the exogenous feed enzymes. Consequently, we sought to better understand the role played by one anti-nutrient, polyphenols, and its role in muted exogenous phytase and protease performance in monogastric diets containing sorghum. Polyphenols from three commercially relevant sorghum grains, and two commercial tannin extracts, were first characterised to better understand the anti-nutrients of interest. Metabolomic analyses revealed a complex polyphenol-like environment which lacked the traditional, large polyphenol anti-nutrients of historic sorghum grains. A multi-method approach allowed for layers of complexity to be revealed and indicated that simpler spectral methods were better suited for fingerprinting than mass spectrometry. The polyphenol extracts were next tested as in vitro inhibitors of exogenous protease and phytase activity. The two commercial tannins, grape seed and quebracho wood, strongly inhibited both enzymes at low concentrations. Sorghum polyphenol extracts had a weaker effect on both enzymes, particularly the protease. Finally, the extracts were incorporated into a standard poultry diet in a simulated in vitro digestion model to measure their effects on nutrient digestibility. In this complex environment, all extracts had minimal effects on both protein and phosphorus digestibility. A rapid mass spectrometry method was trialled to fingerprint the supernatant of different diets with varying degrees of success. The results found in this work indicate that while modern sorghum grains may have minimal impact on exogenous enzyme activity, attention is needed at the metabolite level to determine which anti-nutrients may be implicated in sorghum's performance variability.