Incorporation of magnetic microparticles (~ 1 um) at electrode structures increases electron transfer e¢ ciency, observed as increased current, for multiple electrochemical systems. Current increases occur with magnetic field. Inclusion of magnetic materials into the cathode matrix of alkaline MnO2 batteries requires the materials to be stable in the strong base electrolyte, typically 6 to 9 M KOH. Samarium cobalt magnetic particles sustain strong permanent magnetic fields and are stable in base without surface modification. Studies were undertaken at fast (C/2), moderate (C/3), and slow (C/5) constant current discharges. Here, alkaline MnO2 batteries generated increased power and energy when magnetic microparticles are incorporated into the cathode of the battery. Because of anode limitations in the battery, total coulombic output is not increased for the first electron discharge, but the available power and energy is significantly higher compared to nonmagnetic batteries at voltages above 0.9V. Constant current discharge curves of magnetic batteries demonstrate higher voltages than nonmagnetic batteries at a given time, which translates to greater power output. This effect is also observed by electrochemical impedance spectroscopy, where charge transfer resistance is less for magnetically modified cells. This work also developed voltammetric measurement protocols for acetone concentration collected in the liquid and vapor phase and measured in solution. Acetone on the breath is an indicator for physiological dysregulation. Measurements are demonstrated for acetone concentrations across the human physiological range, 1 uM to 10 mM at platinum electrodes in 0.5 M H2SO4. Effects arise through adsorption of acetone from the gas phase onto a platinum surface and hydrogen in acidic solution within the voltammetric butterfly region. The protocol is demonstrated to yield breath acetone concentration on a human subject within the physiological range and consistent with ketone urine test strip.

This thesis describes research to understand the relationships between materials, microstructure, transport processes, and battery performance for primary alkaline battery cathodes. Specifically, the effect of various carbon additives, with different physical properties, on electronic transport or conductivity within battery cathodes was investigated. Generally, the electronic conductivity increases with carbon additives that have higher aspect ratios, smaller particle diameters, higher surface areas, and lower bulk densities. Other favorable carbon aspects include more aggregated and elongated carbon domains which permit good particleto-particle contacts. Of the various carbon additives investigated, graphene nanopowder was the best performer. This graphene nanopowder had the smallest particle diameter, highest surface area, and one of the lowest Scott densities of the carbon additives investigated as well as well-connected, interspersed carbon pathways. Notably, a typical effective ionic conductivity is more than 50 times less than the electronic conductivity (5.7 S/m to 300 S/m, respectively) for a high-performance cathode. Thus, alkaline battery cathodes could be redesigned to improve ionic conductivity for optimal performance. This work expanded on previously published work by relating additional carbon-additive material properties--specifically, particle morphology, surface area and Scott density--and their corresponding cathode microstructure to the fundamental transport processes in alkaline battery cathodes.

The goal of this work is to further understand the relationships between porous electrode microstructure and mass transport properties. This understanding allows us to predict and improve cell performance from fundamental principles. The investigated battery systems are the widely used rechargeable Li-ion battery and the non-rechargeable alkaline battery. This work includes three main contributions in the battery field listed below. Direct Measurement of Effective Electronic Transport in Porous Li-ion Electrodes. An accurate assessment of the electronic conductivity of electrodes is necessary for understanding and optimizing battery performance. The bulk electronic conductivity of porous LiCoO2-based cathodes was measured as a function of porosity, pressure, carbon fraction, and the presence of an electrolyte. The measurements were performed by delamination of thin-film electrodes from their aluminum current collectors and by use of a four-line probe. Imaging and Correlating Microstructure To Conductivity. Transport properties of porous electrodes are strongly related to microstructure. An experimental 3D microstructure is needed not only for computation of direct transport properties, but also for a detailed electrode microstructure characterization. This work utilized X-ray tomography and focused ion beam (FIB)/scanning electron microscopy (SEM) to obtain the 3D structures of alkaline battery cathodes. FIB/SEM has the advantage of detecting carbon additives; thus, it was the main tomography tool employed. Additionally, protocols and techniques for acquiring, processing and segmenting series of FIB/SEM images were developed as part of this work. FIB/SEM images were also used to correlate electrodes' microstructure to their respective conductivities for both Li-ion and alkaline batteries. Electrode Microstructure Metrics and the 3D Stochastic Grid Model. A detailed characterization of microstructure was conducted in this work, including characterization of the volume fraction, nearest neighbor probability, domain size distribution, shape factor, and Fourier transform coefficient. These metrics are compared between 2D FIB/SEM, 3D FIB/SEM and X-ray structures. Among those metrics, the first three metrics are used as a basis for SG model parameterization. The 3D stochastic grid (SG) model is based on Monte Carlo techniques, in which a small set of fundamental inter-domain parameters are used to generate structures. This allows us to predict electrode microstructure and its effects on both electronic and ionic properties.

Battery technology is a great candidate for energy storage applications. The need for high-performance and cost-effective batteries has motivated researchers to put much effort into improving battery performance. In this work, we attempt to understand the elements that affect the microstructure and performance of two battery systems. The first part of this work focuses on the investigation of transport and structural properties of porous electrodes in an alkaline electrolyte. A DC polarization method was deployed for tortuosity measurements. An apparatus was designed to flow specified current through and measure the voltage drop over the porous electrodes. Using a modified Ohm's law, effective diffusion coefficient and associated tortuosity were determined. Multiple compositions (different types and amounts of conductive additives) were tested to understand the effects of composition on the transport properties. As a validation and to further understand the tests, a model was developed and used for data analysis. The second part of this dissertation describes simulations of the manufacturing process of a Li-ion electrode. LAMMPS, a particle simulator, was used for this meso-scale particle-based simulation. The interactions between particles were understood by model-experiment comparisons of the macroscopic properties such as viscosity of the slurry and elasticity of the dried film. The microstructure created by this simulation was consistent with the one we observed in SEM/ FIB images. Although the emphasis was the drying process in this part, some preliminary coating and calendering simulations are presented. Finally, the effects of electrode heterogeneity were investigated by a Newman-type model and tomographic images. An electronic conductivity map was initially generated over a Li-ion cathode. Then SEM/FIB images of specified high, middle, and low conductivity regions were taken to confirm heterogeneity. For modeling purposes, three regions of high, middle, and low ionic resistance were considered connected in parallel, representing the real electrode heterogeneity. Multiple cases of heterogeneities such as non-uniform ionic resistance and active material loading at low, middle, and high charge-discharge rates were studied. The results show that higher rates increase non-uniformities of dependent properties such as temperature, current density, positive and negative electrodes states of charge, and charge and discharge capacities especially in charging cases.

In this thesis suggest the involvement of appropriate driver for mobile phone travel charger. The work is a treatise on the available accumulators, which can be used as a source for the proposed power converter.

This thesis deals with the establishment of zinc ions at the positive electrode of nickel-zinc batteries. The aim of the study was to measure the impedance characteristics of the positive electrode in various states of charge and observing the effect of ZnO on the changes of impedance spectra. The theoretical part is focused on nickel hydroxide as a construction material for positive electrode and its behavior during cycling in the electrolyte. The experimental part describes in detail the manufacture of the electrode system and the preparation of electrolytes with different degrees of saturation with zinc oxide. The cells were cycled and measured using impedance spectroscopy. The measured impedance curves were simulated with equivalent circuits for a better understanding of the ongoing processes.