Investigation of adsorption-related properties of potassium hydroxide activated carbon and its derivatives design, experimental analysis, and modeling of multiple battery chemistries
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[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] This dissertation covers an evolution of topics starting with research on high surface area activated carbon, continuing with the application of that carbon in a new battery design referred to as the convection battery, and concluding with modeling and parametric studies on the convection battery. High surface area (>3000m2/g) activated carbons have been developed via potassium hydroxide (KOH) activation. The production process an extreme pyrolysis step with the use of phosphoric acid, and a high temperature activation step with the use of KOH. The surface area and pore size distributions were investigated under different KOH loadings. Higher KOH loadings yield higher surface area and a much larger population of larger pores. High surface area briquettes (>2000m2/g) have also been produced with this activated carbon and polyvinylidene chloride (PVDC), with the intention of achieving higher uptake of methane per unit volume. The highest uptake of methane per unit volume is achieved with a PVDC content of 20% by mass. The ability to produce activated carbons with a range of properties was used as an enabling technology to research several different battery chemistries have been investigated in multiple cell layouts. The effect of ultrasonic waves on zinc manganese oxide batteries was researched, and it was found that the application of these waves has a significant effect on the performance of the batteries. Battery capacity can improve by more than 10% with the application of a low power (80W) sonicator. As the limits of battery performances were pushed, the separator material was identified as being critical to maximize performance. The effects of the sonication are more pronounced when the separator is more porous. The modeling of a lithium iron phosphate (LiFePO4) convection cell was also investigated. An existing COMSOL model with very good qualitative predictions was improved quantitatively by the addition of a solid phase ionic conductivity term in the separator and by manipulating a few other key parameters. On plots of cell capacity vs. current density, average variances between experimental and modeled data were reduced by over 80% relative to earlier work that did not consider the ionic conductivity of the separator material.
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