Doctor of Philosophy (PhD), Ohio University, 2010, Physics and Astronomy (Arts and Sciences)

Scandate dispenser cathodes have demonstrated an immense improvement in current densities for thermionic cathodes. However, the emission properties are inconsistent from cathode to cathode. The cathodes also lack the lifetime desired for space based applications. Further scientific investigation of the reason for the increased electron emission and limited life is needed to solve the manufacturing inconsistencies and limited lifetimes. Radio frequency magnetron sputter deposited thin film squares (25 x 25 μm and 100 x 100 μm) of barium, scandium and the oxides of both were prepared in a variety of configurations on tungsten and scandium foils for study and characterization of electron yield in a photoelectron emission and thermionic electron emission microscope (PEEM/ThEEM) fitted with a Faraday cup for current density measurements. The samples were studied from a room temperature to brightness temperatures in excess of 1600 K. It was determined that sub-monolayer oxide coverage is not necessary for increased current densities. It was discovered that application of a 200 nm thin film of scandium oxide increases the electron yield of tungsten, and the increased yield is dependent on the interface between these two materials. Barium oxide on top of scandium oxide also increased the electron yield. Both barium and scandium metal wet the surface of tungsten, and thus their physical position cannot be controlled. Barium oxide and scandium oxide, however, presented physical stability to brightness temperatures of 1600 K and above. A model is presented, using data acquired from ThEEM, UPS and TES, explaining the increased electron yield and transport through thick oxide layers. The model proposes electron injection from tungsten into a gap state in scandium oxide. This gap state is above the lowest occupied orbital, and is proposed to be in the 3d electron levels of scandium. Electrons in the gap state are then free to move to the surface, where they have an effectively lo (open full item for complete abstract)

Committee: Martin Kordesch Ph.D. (Advisor); David Ingram Ph.D. (Committee Member); Eric Stinaff Ph.D. (Committee Member); Wojciech Jadwisienczak Ph.D. (Committee Member) Subjects: Physics

Doctor of Philosophy, The Ohio State University, 2019, Mechanical Engineering

Metal-oxygen batteries are an emerging class of energy storage devices that have some of the highest energy densities among secondary batteries. These batteries are unique because molecular oxygen is the active cathode material and is not stored in the cathode structure. During discharge, oxygen diffuses to an active cathode site, gets reduced on the surface on the cathode, and forms a metal oxide with the cation. The regulation of molecular oxygen concentration throughout the battery therefore becomes critical for battery performance. In particular, oxygen should be present in the cathode in sufficient concentrations but be prevented from diffusing to the anode. The process of oxygen diffusion to anode is known as oxygen crossover and poisons the anode surface, limiting the cycle life of the battery. The goal of this dissertation is to increase the cycle life of potassium-oxygen batteries by preventing molecular oxygen crossover and is achieved with conducting polymer membranes and functionally-graded cathode architectures. This work demonstrates that polypyrrole (PPy) electropolymerized on a porous membrane serves an effective oxygen barrier and increases cyclability. Dopant selection is found to have a strong influence on both ion transport properties and cycle stability in the DME-based electrolyte used for K-O2 batteries. PPy membranes doped with dodecylbenzenesulfonate (DBS-) increase the cycle life from 4 to 18 cycles by transporting K+ and blocking oxygen. However, electrochemical cycle stability of PPy(DBS) cathodes in DME is found to be poor. Bilayer bending studies are performed, and it is determined that the cycle stability depends on the mechanical boundary condition (free versus fixed). The free membrane has improved cycle stability compared to the fixed membrane, which is attributed to the higher cyclic compressive stresses in fixed membrane as estimated by a beam bending model. The presence of oxygen causes further degrades the cyclabi (open full item for complete abstract)

Committee: Vishnu Sundaresan (Advisor) Subjects: Mechanical Engineering

Doctor of Philosophy (PhD), Ohio University, 2015, Physics and Astronomy (Arts and Sciences)

Model thin film thermionic cathodes with various deposition geometries are grown by physical vapor deposition. Model cathodes are examined under thermionic emission microscopy, field emission scanning electron microscopy, optical microscopy, Raman spectroscopy and energy dispersive X-ray spectroscopy for thermionic emission and thermochemistry properties. The best thermionic electron emission is observed from the areas that are completely devoid of bulk materials at the end of the cathode life. From these areas, it is determined the presence of barium oxide promotes desorption of scandium oxide. At the poor emission areas, crystalline compounds are found and are uniquely identified by Raman spectroscopy as BaWO4, Ba2WO5, long chain linear tungstates (νas = 860cm-1) and Sc2O3. There is no evidence from Raman spectroscopy that tetrahedral Sc2(WO4)3 is present or forms on the surface of the model cathodes, or for the presence of Ba3WO6.

Committee: Martin Kordesch Dr (Advisor); Nancy Sandler Dr (Committee Member); Eric Stinaff Dr (Committee Member); Eric Masson Dr (Committee Member) Subjects: Materials Science; Physics

Master of Science, The Ohio State University, 2013, Mechanical Engineering

Lithium-ion (Li-ion) batteries have become very prominent as a form of energy storage for numerous applications due to its high energy and power densities. They are used for numerous portable devices and more recent electric vehicles (EVs). It is important to increase the cycle life of Li-ion batteries in order for them to be more viable for the automotive industry. With use, these batteries undergo an aging process which reduces the battery storage capacity and increases internal resistance. To reduce the aging process it is essential to first understand the degradation mechanisms on the electrodes of the battery. A multi-scaled approach has been previously applied to the study of the degradation of the LiFePO4 cathodes. It has been shown that nanoparticles in cathodes coarsen as a result of aging. Coarsening of nanoparticles has been shown to lead to an increase in surface resistance and decrease in surface conductivity, which is responsible for reduced lithium retaining capacity. It is therefore important to study the cause of these aging mechanisms in order to increase the life of the battery. An in depth study of cathode on the nanometer scale is necessary using atomic force microscope (AFM) related techniques. In this work, both ex-situ and in-situ studies were conducted to understand the aging phenomenon in LiFePO4 battery cathodes. High resolution AFM imaging and current measurements were conducted to study the difference of the unaged cathode from the aged. This was done to quantify the coarsening process. Particle agglomeration was observed in the aged cathode, which is believed to reduce surface conductivity. Nanomechanical characterization and mechanical integrity studies were then conducted on unaged and aged cathodes using AFM equipped with nanoindentor. This was done to determine the effect of increased internal stress within the cathode created during aging on the nanomechanical and mechanical integrity properties. Propertie (open full item for complete abstract)

Committee: Bharat Bhushan (Advisor) Subjects: Mechanical Engineering

Master of Science (M.S.), University of Dayton, 2010, Mechanical Engineering

A solid state lithium-air battery is receiving considerable attention by the battery community recently. A challenging part of making a solid state lithium-air battery is to develop a solid state air-cathode. The present study relates to the development of the air-cathode. The air-cathode consists of a lithium ion conducting material, electron conducting material, metal substrate, binder and dispersant. For lithium ion conduction Lithium aluminum germanium phosphate (LAGP) glass-ceramic powder was used. For electron conduction two types of carbon were used. One type of carbon help in providing better electron conductivity and the other type of carbon helps in pore formation in the cathode. Nickel mesh/foam was used for structural support and current collection. Polytetrafluoroethylene (PTFE) was used to bind LAGP and carbon. Dispersant was used for preventing LAGP and carbon powders from agglomerating. The investigation includes evaluation of processing parameters including the effect of LAGP or dispersant concentration on the rate capacity. LAGP glass was prepared at 1350°C and crystallized at 850°C for 12 hours to transform it into a glass- ceramic. The cathodes prepared from the batch materials and processed were characterized to determine porosity, surface area, pore size and volume. To evaluate the electrochemical properties of these cathodes twelve lithium-air cells were fabricated and tested in the temperature range 45 – 115°C and were characterized using a Solartron 1260 impedance analyzer with 1287 electrochemical interface in oxygen atmosphere under 1 kPa pressure.It was determined that the use of dispersant helped the cathode obtain a porosity of 22% which is due to the proper dispersion of LAGP in cathode. A dispersant concentration of 5.92 wt% helped the cell discharge at a voltage of 2.5 V for 35 hours and achieved a capacity of 14.1 mAh at 75°C. LAGP concentration of 90 wt% helped in discharging the cell with a current of 0.50 mA for 13 hours at 75°C. (open full item for complete abstract)

Committee: Dr. Binod Kumar PhD (Committee Chair); Dr. Margaret Pinnel PhD (Committee Member); Dr. Vinod K Jain PhD (Committee Member) Subjects: Materials Science; Mechanical Engineering

Master of Science, The Ohio State University, 1969, Graduate School

Committee: Not Provided (Other) Subjects:

Doctor of Philosophy, The Ohio State University, 2024, Chemistry

Energy storage requires a multifaceted approach to satisfy the energy demands of modern civilization. Most large-scale physical methods for storing energy, such as pumped hydro, flywheel, or gravity batteries, are not viable for personal and portable use. The need for personal energy storage has motivated the development of lithium-ion batteries (LIBs). However, most of these energy storage systems employ metal-based electrode materials, which are environmentally detrimental and unsustainable. Organic electrode materials (OEMs) provide a foundation of materials that are derived from abundant feedstocks, have high synthetic versatility, and diverse redox chemistries. However, research into the methodology for developing inexpensive OEMs from abundant feedstocks has been lacking. One of the largest issues with OEMs is their high solubility in organic solvents, which leads to rapid capacity decay. To address these two issues, we strategically selected motifs that could be synthesized on a gram scale with high modularity, and I investigated their performances in aqueous electrolytes, which reduces solubility and enhances their performance. My graduate research focuses on the application of OEMs in aqueous zinc-ion batteries (AZIBs), due to the natural abundance of zinc and enhanced safety feature of aqueous electrolyte. In the second chapter, I present the investigation of 1,2,4,5-tetrazine derivatives as low-cost and synthetically modular organic electrode materials in rechargeable aqueous Zn-ion batteries (AZIBs). The substituents at the 3,6-positions of the tetrazine were found to be critical for cycling stability. While heteroatom substituents (chloro, methoxy, pyrazole) lead to the rapid decomposition of electrode materials in the electrolyte, the installation of phenyl groups enhances the cycling stability via π-π stacking. Spectroscopic characterization suggests a cooperative zinc and proton insertion mechanism. This unique cooperativity of zinc and proton le (open full item for complete abstract)

Committee: Shiyu Zhang (Advisor); Yiying Wu (Committee Member); Casey Wade (Committee Member) Subjects: Chemistry

Doctor of Philosophy, The Ohio State University, 2024, Mechanical Engineering

To meet the growing demands of electric vehicles and energy storage devices, it is essential to develop advanced lithium-ion batteries (LIBs) that not only provide high energy density but also affordability and rapid charging and discharging capabilities. Cathode materials account for over 40% of the total cost of a battery and directly determine the battery's voltage and capacity. Therefore, it is imperative to develop low-cost cathode materials with high electrochemical performance. In this dissertation, we explored several cobalt-free cathode materials, including spinel-structured LiNi0.5Mn1.5O4 (LNMO), nickel-rich cobalt-free LiNi0.95M0.05O2 (M=Al, Mn, Mg, and Ti) layered oxides and xLi2MnO3·(1 – x)LiMO2 (M = Ni and Mn) layered oxides (LMR), which have the advantage of low raw materials price compared to commercialized cathode materials, such as LiCoO2 and cobalt-rich LiNi0.33Co0.33Mn0.33O2 (NMC111) layered oxides. However, like most cathode materials, they also encounter significant challenges, including low thermal stability, an unstable internal structure, and rapid capacity fading, which is caused by serious anisotropic volume changes during cycling, continuous electrolyte decomposition, and transition metal dissolution, particularly at high operating voltages. To overcome these challenges, we present three advanced strategies aimed at producing intergranular-crack-free cathode materials with superior cycling performance, high internal structure stability, and minimal parasitic reactions even under severe cycling conditions. Firstly, employing solid-state electrolytes as Li-ion conductors to form a stable cathode electrolyte interphase (CEI) layer. Secondly, establishing a concentration-gradient layered oxide with a Ni-rich core and an enrichment of substituted elements in the surface region through a co-precipitation reactor. The presence of a Ni-rich core enhances the material's capacity, while the transition elements at the surface ensure excellent cycla (open full item for complete abstract)

Committee: Jung-Hyun Kim Dr. (Advisor); Jay Sayre Dr. (Committee Member); Stephanie Stockar Dr. (Committee Member); Lei Raymond Cao Dr. (Committee Member) Subjects: Materials Science; Mechanical Engineering

Doctor of Philosophy, University of Akron, 0, Polymer Science

Lithium-ion batteries (LIBs) are crucial energy sources across diverse sectors, from medical devices in nanotechnology to grid energy storage. However, their liquid electrolytes pose significant safety risks, particularly during overheating, leading to battery explosions. This hazard is especially pronounced in electric vehicles, where breaches can trigger catastrophic cell explosions. Solid-state batteries (SSBs) have emerged as a promising alternative, offering enhanced safety by replacing liquid electrolytes with solid-state electrolytes (SSEs). Despite this, scaling up LIB production and improving energy and power density remain significant challenges. Chapter I presents a novel approach using 3D printing technology to fabricate solid polymer electrolyte membranes for SSBs. This method replaces conventional polymer separators and liquid electrolytes with a thin, ionically conductive composite based on poly(ethylene glycol) diacrylate (PEGDA) reinforced with polyamide for mechanical strength. Using a digital light processing (DLP) 3D printer, we created thin SSE films. Lithium plating/stripping tests showed that the printed PEGDA/polyamide electrolyte maintained stable cycling performance over 1,400 hours at a current density of 0.05 mA/cm². Additionally, LIBs with the 30 μm polyamide-reinforced electrolyte exhibited excellent cyclability at a 0.2 C rate under ambient conditions (30°C). Chapter II addresses issues with traditional cathode electrode processes, such as the insulating polyvinylidene fluoride (PVDF) binder and toxic organic N-methyl-2-pyrrolidone (NMP) solvent. We introduced a solvent-free electrode processing technique using a thermal cross-linkable polymer electrolyte as a binder substitute. This method allows the creation of higher mass loading electrodes without volatile organic compounds (VOCs). Cathode electrodes were prepared on the current collector using hydraulic thermal pressing, with adjustments to the pressing force. Structural parameter (open full item for complete abstract)

Committee: Yu Zhu (Advisor); Steven S.C. Chuang (Committee Chair); Chunming Liu (Committee Member); Weinan Xu (Committee Member); Tianbo Liu (Committee Member) Subjects: Chemistry; Energy; Materials Science

Doctor of Philosophy, The Ohio State University, 2024, Mechanical Engineering

The emergence of electric vehicles (EVs) along with the movement toward “zero-emission” has put the lithium-ion batteries (LIBs) system as a pivotal technology for a sustainable future. While the LIBs offer high energy density, extended cycle life, and fast charging capabilities, the battery system always has been incorporated with safety concerns due to the flammable liquid electrolytes used for traditional LIBs. Solid electrolytes (SEs) offer as a promising solution to replace liquid electrolytes, enhancing safety and performance. However, there are challenges associated with SEs, including low ionic conductivity of SE materials, large interface resistance, chemical instability between electrode and electrolyte, and Li-dendrite growth, necessitate thorough investigation. Especially, the interface between cathode and solid electrolyte materials is a critical focus, requiring compatibility with SEs in the selection of a cathode active materials (CAM) for the development of all-solid-state battery system. This dissertation explores various types of cathode materials for integration into all-solid-state Li-ion battery systems. For example, layered cathode materials with various Ni/Mn/Co compositions (LiNixMnyCo1-x-yO2 (NMC)) were explored, revealing the degradation behavior against the moisture impact, which is a crucial factor for the practical applications. Li-Mn-rich cathode has prominent features of high energy and power density. While it exhibits large irreversible capacities and rapid degradation over cycles, strategies such as core-shell synthesis and fluorine substitution were applied to address the defects. Meanwhile, aluminum substituted spinel cathode LiCo1-xAlxO2 (x = 0 – 0.3) was introduced along with its “zero-strain” property, which is an attractive feature for the all-solid-state battery application. It was confirmed that Al-doping can effectively suppress the evolution of impurity phase and structure decomposition over extended cycles. On the other (open full item for complete abstract)

Committee: Seung Hyun Kim (Committee Member); Jay Sayre (Committee Member); Jung-Hyun Kim (Advisor) Subjects: Automotive Engineering; Automotive Materials; Chemical Engineering; Materials Science; Mechanical Engineering

Doctor of Philosophy (Ph.D.), University of Dayton, 2023, Electrical Engineering

Lithium-ion batteries (LIBs) have transformed modern electronics and rapidly advancing electric vehicles (EVs) due to high energy, power, cycle-life, and acceptable safety. However, the comprehensive commercialization of EVs necessitates the invention of LIBs with much enhanced and stable electrochemical performances, including higher energy/power density, cycle-life, and operation safety but at a lower cost. An unprotected lithium-ion battery (LIB) cell cathode using lithium metal anode and organic carbonate liquid electrolyte undergoes significant structural damage during the cycling (Li+ intercalation/ deintercalation) process. Also, a bare cathode in contact with a liquid electrolyte forms a resistive cathode electrolyte interface (CEI) layer. Both the cathode structure damage and CEI lead to rapid capacity fade. Different strategies have been used to mitigate the degradation of LIB electrodes, including designing electrolytes to enhance SEI/CEI formation, cycle stability, interface engineering with protective coatings to prevent the breakdown of active material particles during cycling, composition control of the electrode particles, synthetic optimization to control particle morphology, the use of composites made from conductive scaffolds and active materials and designing new electrode architectures to overcome volume changes and enhance transport properties. Cathode surface modification has been used to reduce CEI formation and structural damage, improving capacity retention, cycle life, energy density, power density, and safety of a LIB. Recently, the coating of the cathode with an intermediate layer (IL), which is transparent to Li+ conduction but impermeable to electrolyte solvent, has been developed to minimize CEI formation and structural damage. IL based on Li+ insulating ceramics, such as aluminum oxide (Al2O3), tin oxide (SnO2), and magnesium oxide (MgO), has been developed but to limited success in mitigating the above cathode degradation. The (open full item for complete abstract)

Committee: Dr. Jitendra Kumar (Committee Chair); Dr. Guru Subramanyam (Committee Member); Dr. Feng Ye (Committee Member); Dr. Vikram Kuppa (Committee Member) Subjects: Electrical Engineering; Energy; Engineering

Doctor of Philosophy, The Ohio State University, 0, Physics

A search is presented for long-lived particles in 113-118 fb-1 of proton-proton collision data produced by the CERN LHC at a center-of-mass energy of 13 TeV collected by the CMS detector in 2016, 2017, and 2018. Events originate from long-lived particles propagating a measurable distance through the CMS detector before decaying into leptons. Background-only hypotheses are consistent with the observations. Limits are set on the product of the top squark pair production cross-section and the branching fraction to a lepton and a b or d quark through an R-parity-violating vertex. Squarks with masses up to 1500 GeV are excluded at a confidence level of 95% for a proper decay length hypothesis of 2 cm An additional search for long-lived particles using B parked data taken from CMS in 2018 is presented. The search is analogous to the previous with a different dataset, triggers and background estimation variables. Preliminary studies demonstrate good sensitivity at low masses not reachable by nominal CMS data. The CSC subdetector electronics of CMS have been successfully upgraded during LS2 to withstand higher data-taking rates and have higher chamber occupancy in preparation for the HL-LHC expected in 2026. Upgrades to the inner CSCs where done: the CFEBs and ALCTs have been upgraded to DCFEBs, and more powerful FPGA-equipped ALCTs. The TMB peripheral boards were upgraded to OTMBs to receive optical readouts from DCFEBs and ALCTs; the LVDB was replaced to provide the appropriate voltage for the new DCFEBs.

Committee: Chris Hill (Advisor); Annika Peter (Committee Member); Linda Carpenter (Committee Member); Antonio Boveia (Committee Member) Subjects: Physics

Doctor of Philosophy, The Ohio State University, 2021, Mechanical Engineering

Lithium-ion batteries (LIBs) are a core component in electric vehicles (EVs). They provide energy to run EVs by converting the stored chemical energy into electrical energy. The quality of the battery system determines the cost of EVs' and single charge driving range. Hence, it is required to develop advanced LIBs and/or alternative battery systems with higher energy and power densities. Recently, solid-state lithium-ion batteries (SS-LIBs) are in-focus as they provide additional benefits in-terms of safety and feasibility for high energy-density EVs. Since, the LIB technology is solely concentrated on electrochemistry, the degradation mechanisms can be figured out by understanding the interface between electrode/electrolyte (both liquid- and solid-electrolyte), which helps in improving cell design for advanced batteries. However, understanding the interfacial degradation mechanisms of LIBs and SS-LIBs still remains the biggest challenge owing to its difficulty to treat micro-scale. This dissertation focuses on understanding battery degradation mechanisms, improving cell designs by surface modification, suggesting novel electrode materials, and showing the optimized interface between electrode/electrolyte for solid-state LIBs. In order to investigate the interfacial studies, a variety of materials characterization techniques were conducted, and diverse electrochemical evaluations were performed. This study will widen the insight into advanced lithium-ion batteries.

Committee: Jung-Hyun Kim (Advisor); Hanna Cho (Committee Member); Marcello Canova (Committee Member); Giorgio Rizzoni (Committee Member) Subjects: Chemical Engineering; Materials Science; Mechanical Engineering

Doctor of Philosophy (PhD), Ohio University, 2021, Chemical Engineering (Engineering and Technology)

Incorporation of potassium bifluoride (KF-HF) as an additive to lithium-halide electrolyte for thermal batteries was investigated. Results indicated that it is feasible to maintain a relatively high ionic conductivity at temperatures (250-300 C) lower than current thermal battery electrolytes (400-550 C). Mixtures of lithium fluoride and potassium bifluorides with the 40-60 wt.% provided the best ionic conductivity at 260 C. Ceramic felts are shown to be an effective alternative to widely used MgO. One of the major benefits of ceramic felts is their high porosity and low weight. LiSi/FeS2 thermal cells with YSZ and Al2O3 ceramic felt electrolyte/separators reported specific energy of 58.47 Wh kg-1 and 43.96 Wh kg-1. Pellet design pyrite (FeS2) cathodes for thermal batteries usually have low electronic conductivity. A new cathode design was developed using iron particles. By adding 11 wt.% Fe particles to the cathode the ohmic polarization was reduced by 17.5% while the available capacity was increased by 78% over the cell with traditional cathode pellet with no electrically conductive particle additives.

Committee: Gerardine Botte (Advisor); Valerie Young (Advisor) Subjects: Chemical Engineering; Energy; Engineering

Doctor of Philosophy (PhD), Wright State University, 2019, Engineering PhD

Drop on demand (DOD) inkjet printing has been widely investigated for its low cost, noncontact, high throughput, and reproducible process advantages. This dissertation research sought to capitalize on these advantages for use in micro solid oxide fuel cells (micro SOFCs). Understanding the important variables underpinning the inkjet process, including ink formulation, jet kinematics, and process settings was essential. These variables were evaluated for their impact on drop deposition quality, resolution, microstructure, and electrochemical functionality, with the end goal of making submicron to micron scale ceramic features. Initially, the fluid kinematics of single pass printing was investigated using a dilute, solid-solvent, colloidal, ink suspension of of La0.6Sr0.4Fe0.8Co0.2O3 (LSFC) and α-terpineol. Favorable process conditions were identified that attained uniform, well-shaped, circular dots ~ 0.1 μm thick and ~ 80 μm in diameter. Multiple, sequential ink passes were employed to increase feature dimensions on the x/y/z axes. This required additional process constraints to control deposition quality and resolution of micro features including micro-dots (0-D), micro-lines (1-D) and micro-planes (2-D). Using optimal conditions, 0-D dots and 1-D lines with x/y dimensions < 100 μm and z axis dimensions < 1 μm with dense, open or networked microstructures were demonstrated; in addition 2-D planes having smooth surface and continuous intra-planar ceramic coverage with dimensions as small as ~ 100 μm by ~ 100 μm were achieved. Sintering the inkjetted submicron prototypes produced consolidated submicron films that were uniform, smooth and void of defects such as cracks or delamination. Thermal treatments resulted in grain growth from an average crystallite size of ~158 nm to ~ 356 nm. Heat treatments < 800°C were essential to avoid deleterious effects on electrochemical activity. Electrochemical characterizations of prototypes produced tolerable peak power (open full item for complete abstract)

Committee: Hong Huang Ph.D. (Advisor); Sharmila Mukhopadhyay Ph.D. (Committee Member); Jason Deibel Ph.D. (Committee Member); Lei Kerr Ph.D. (Committee Member); Thomas Reitz Ph.D. (Committee Member) Subjects: Engineering; Materials Science

Master of Science, The Ohio State University, 2018, Mechanical Engineering

Electrochemically inert materials in Li-ion battery cathodes, such as carbon additives and binders, reduce the volumetric and gravimetric energy density of cathodes by occupying volume and mass, without storing energy. This work eliminates the carbon additives and reduces PVdF content by incorporating an electronically conductive polymer. Studies of the Ni(CH3-Salen) material with a carbon network proved that Ni(CH3-Salen) provides a unique in-situ polymerization, which allows the incorporation of the material without changing existing manufacturing procedures. Ni(CH3-Salen) was found the be electrochemically stable between 2.5 – 4.1V vs. Li/Li+, with good cycle life and C-Rate performance. Incorporating the Ni(CH3-Salen) polymer with a LiFePO4 (LFP) cathode provided increased cycle life, increased C-Rate performance, increased energy density, and decreased impedance compared to conventional LFP cathodes with Super P and PVdF.

Committee: Jung-Hyun Kim PhD (Advisor); Marcello Canova PhD (Advisor) Subjects: Mechanical Engineering

Master of Science, University of Akron, 2018, Polymer Science

Lithium-ion battery technology has been proved to be a great success in the application of portable energy storage devices. Current lithium-ion battery technology with low capacity and poor safety performance does not meet the future requirement in portable electric appliances and plug-ion vehicles. Post-Li metallic battery technology, magnesium battery, provides excellent volumetric capacity (3850 mAh/cm3) with relatively high redox potential (-2.4 V vs SHE) as well as high safety in low cost. In this thesis, the focus is on exploring the electrochemical behaviors of anatase TiO2 nanotubes as cathode materials in rechargeable magnesium batteries and studying the electrochemical behaviors of All-phenyl complex electrolyte system during discharge and charge process. TiO2-based host material had been widely studied in the utilization in Li-ion batteries, however, rare reported in magnesium batteries. Here, we used hydrothermal process to synthesize anatase TiO2 nanotubes (NTs), which exhibited high capacity of ~125 mAh/g at 33 mA/g and good capacity retention after 80 cycles with working potential range from 0.5 to 1.8 V. Anatase TiO2 NTs shows great promise as Mg2+ ions host materials, allowing high reversibility of Mg2+ ions intercalation/de-intercalation in rechargeable Mg batteries. All-phenyl complex electrolyte is synthesized through the in situ transmetalation reaction between Grignard reagent (PhMgCl) and Lewis acid (AlCl3), with tetrahydrofuran as solvent. The electrolyte components content species including MgCl+, Mg2Cl3+, PhyAlCl4-y-, etc. The THF solvated structures helps to stabilize the anions and cations. Here, we used in situ infrared spectroscopy technology to study the electrochemical behaviors of electrolyte components and observe the intercalation/de-intercalation process of Mg2+ ions. The understanding of electrochemical behaviors of electrolyte helps to further modify and synthesize a more stable and safe electrolyte with wide potential windo (open full item for complete abstract)

Committee: Steven Chuang (Advisor); Yu Zhu (Committee Member) Subjects: Energy; Polymer Chemistry

Doctor of Philosophy, The Ohio State University, 1974, Graduate School

Committee: Not Provided (Other) Subjects: Computer Science

Master of Sciences, Case Western Reserve University, 2017, Materials Science and Engineering

The performance of solid oxide fuel cells (SOFCs) with three different lanthanum strontium manganite (LSM) based cathode compositions were evaluated. All cells were yttria-stabilized zirconia (Zr0.92Y0.08O2-d, 8YSZ) electrolyte-supported button cells, consisting of a nickel oxide – yttria-stabilized zirconia (NiO-8YSZ) anode and a cathode of 8YSZ and LSM. The three LSM compositions differed in the amount of excess Mn: Composition A was (La0.85Sr0.15)0.90MnO3±d (10% excess Mn); Composition B was (La0.80Sr0.20)0.95MnO3±d (5% excess Mn); and Composition C was (La0.80Sr0.20)0.98MnO3±d (2% excess Mn). The cells were tested under conventional and accelerated conditions, where the accelerated conditions were meant to simulate the results of months of long-term testing in just 500 hours (approximately three weeks) of testing by using high operating temperature and current density. Accelerated tests showed lower degradation rates, lower continuous area specific resistance (ASR), and higher power output than conventional tests for all cathode compositions. Continuous measurements of the cells' output voltage versus time, together with periodic electrochemical impedance spectroscopy (EIS) measurements, were used to evaluate the performance of the cells in terms of ASR degradation rates (% ASR rise per kh) and power outputs. The EIS measurements also permitted a partial deconvolution of the cathode ASR from the anode ASR. Cathodes with 10% excess Mn tested under accelerated conditions had the lowest degradation rates, but the highest continuous ASR and lowest power outputs. Cathodes with 2% excess Mn tested under accelerated conditions had the lowest continuous ASR and highest power outputs; thus it was concluded that cells with the lowest amount of excess Mn cathodes performed the best.

Committee: Mark De Guire (Advisor); Arthur Heuer (Committee Member); Roger French (Committee Member) Subjects: Energy; Materials Science

Master of Science (M.S.), University of Dayton, 2016, Electrical Engineering

Wearable electronics and sensors are being extensively developed for several applications such as health monitors, watches, wristbands, eyeglasses, socks and smart clothing. Energy storage devices such as rechargeable batteries make wearable devices to become more independent from power outlets, or in other words, make device portability. Battery energy density determines how long a battery powered device will work before it needs a recharge. Longer the time before battery needs recharge, better it is for device applications. Therefore, the goal of battery researchers and engineers is to develop a battery that can provide high energy density and longer device operation. The state-of-the-art battery is the lithium-ion battery (LIB) technology outperforming any other battery for the aforementioned applications. Even LIB is limited in energy storage (energy density ~200 Wh/kg) and requires frequent battery charge. Some other major challenges associated with LIBs are high cost, low cycle life (restricted to 500 – 1000 cycles), safety, and negative environmental impacts. Further improvement in LIB is very limited as the technology is reaching the theoretical limit and therefore new battery technology with greater energy density and overall better performance must be developed in order to match the ever increasing power demand in fast growing electronics. Lithium sulfur battery (LSB) (energy density ~2600 Wh/kg) is one of the most promising batteries for next generation energy storage, enabling approximately 10 times more energy storage in LSB than LIB. Furthermore, sulfur is inexpensive, abundant and environmental friendly. Therefore, LSB is expected to be more economical, safe and environmentally sustainable compared to LIB. However, performance (cycle life, thermal stability and safety) of current LSB technology do not meet commercialization standards at current development stage and thus, open for further technological advancements. My thesis focuses on the devel (open full item for complete abstract)

Committee: Guru Subramanyam (Committee Chair); Jitendra Kumar (Committee Co-Chair) Subjects: Electrical Engineering