Master of Science in Engineering, University of Akron, 2018, Mechanical Engineering

Battery Thermal Management Systems are necessary for the overall efficiency and life cycle of vehicle as well safety of passengers and vehicle, as elevated operating temperatures have adverse effect on the efficiency, life cycle and safety of the Li-ion battery packs. The operating temperature prescribed by many studies for improved performance and better life cycle of Li-ion batteries is around 25°C. In some worst case scenarios, high operating temperature may lead to thermal runaway in the battery, causing immense amount of heat generation, even leading to an explosion. To avoid all these dangerous events, battery thermal management is utilized to regulate the temperature of the battery pack. In this thesis, a novel battery thermal management system based on liquid cooling principle is proposed. The system involves dual purpose cooling plate for prismatic Li-ion batteries, which can maintain the temperature under normal conditions as well as mitigate the heat generated during thermal runaway. An experiment was performed on the prismatic Li-ion battery to measure the heat generation trends. The battery was discharged at 5C to replicate aggressive conditions. The data for maximum heat flux generated in the Li-ion battery was obtained. An estimated amount of heat generated during thermal runaway was calculated. A conjugate heat transfer method was used to simulate the cooling plates for normal operation and thermal runaway. The plates were simulated with two flow rates for normal operation and three flow rates for thermal runaway. Three different designs of cooling plates were compared on the basis of surface temperature, pressure drop and flow rate. The final design was selected based on the comparison with the rest of the cooling plates. The selected cooling plate can: • Maintain the temperature of battery below 25°C during normal operation. • Dissipate the maximum possible heat generated during thermal runaway and bring the temperature to less than 80°C. • M (open full item for complete abstract)

Committee: Siamak Farhad (Committee Chair); Gopal Nakarni (Committee Co-Chair); Alper Buldum (Committee Member); Reza Madad (Committee Member) Subjects: Mechanical Engineering

Doctor of Philosophy, University of Akron, 2017, Polymer Science

The development and commercialization of rechargeable Li-ion battery in the 1990s has triggered the advancement of modern portable technology. Currently, with the emergence of electric vehicles and more complex gadgets, conventional lithium ion intercalation based secondary batteries could no longer live up to the demands of the end-use consumers. In this dissertation, ordered carbonaceous nanomaterials were utilized to integrate with the next-generation conversion chemistry based secondary batteries. Lithium-oxygen and sodium-sulfur battery systems were tested and developed in attempt to deliver higher energy density over the conventional Li-ion battery. The main objective of the work is to fabricate advanced electrodes that are capable of providing higher capacity in order to facilitate power grids and electric vehicles, while by doing so; the effects caused by the emission of CO2 could be significantly mitigated. Ordered carbonaceous nanomaterials were produced by the chemical vapor deposition method. Among the wide variety of carbon materials, vertically aligned carbon nanotubes were grown on a substrate and then subsequently peeled off and used as the electrode for the lithium-oxygen battery. With the combination of 2-methyl-pyrrolidone solvent, the assembled lithium-oxygen battery could achieve specific capacity of 1200 mAh·g-1 and under safe charge/discharge cycles for 50 cycles. Carbonized metal organic framework was fabricated by mixing selected precursors. Sulfur was melt infiltrated to yield the carbon/sulfur composite. The metal organic framework structure composite cathode exhibited specific capacity of 1000 mAh·g-1 for over 250 cycles for the room temperature sodium-sulfur system. In addition, nitrogen, sulfur co-doped hierarchical porous carbon was fabricated by soft template method and combined with sulfur. The N,S-HPC/S composite showed relatively lower energy density; however, with much higher cycle stability of ~10,000 cycles at a current de (open full item for complete abstract)

Committee: Yu Zhu (Advisor); Steven Chuang (Committee Chair); Mesfin Tsige (Committee Member); Toshikazu Miyoshi (Committee Member); Bryan Vogt (Committee Member) Subjects: Energy; Engineering; Materials Science; Nanotechnology; Polymers

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, 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, University of Akron, 2018, Polymer Science

Since the first and second industrial revolutions, the development of energy conversion and storage technologies have brought great progress and convenience to modern society. Most of the innovations and technologies focus on the carbon-based fuels such as coal, petroleum and natural gas, which are not only limited resources and but also harmful for the environment. Meanwhile, the power demand from industries and societies has been growing rapidly in the recent years. In this consideration, a number of research efforts have been intensively applied to pursue alternative clean energy resources and new energy storage and conversion systems, such as supercapacitors, lithium-ion batteries, metal-oxygen, water electrolysis and so on. In this dissertation, we report the synthesis and preparation of a series of polymer and nanomaterials with controllable composition and structure, to fit for the specific requirement in different systems and promote the device performance. In order to prevent the aggregation of graphene sheets, we designed a method to fabricate 3D macro porous graphene by using bi-continuous polymer templates. The structure and pore size of the graphene can be controlled by corresponding polymer templates. The resulting graphene monolith materials were used as the supercapacitor electrode and exhibited excellent stability (over 6000 cycles with capacity retention of 98%). This work provides a novel way to fabricate high-quality, macroporous graphene that can be useful in applications such as electrochemical energy storage electrodes and high surface area catalyst scaffolds. To investigate the Li-oxygen battery discharge reaction pathway, patterned Au-nanodots as surface-enhanced Raman substrates are prepared by using a universal method of metal deposition through a nano-shadow mask. The discharge products on different electrodes (graphene and gold) were analyzed and the results indicated that the reaction process on the lithium-air cathode was significant (open full item for complete abstract)

Committee: Yu Zhu (Advisor); Toshikazu Miyoshi (Committee Chair); Mesfin Tsige (Committee Member); Steven Chuang (Committee Member); Bryan Vogt (Committee Member) Subjects: Materials Science; Polymer Chemistry; Polymers

Doctor of Philosophy, The Ohio State University, 2018, Materials Science and Engineering

Third generation Al-Cu-Li alloys have improved localized corrosion resistance compared to previous generations and are attractive to the aerospace industry because of the mix of low density and good mechanical properties. Al-Cu-Li alloy AA2099 (Al 2.7Cu 1.8Li 0.6Zn 0.3Mg 0.3Mn 0.08Zr) is a newer precipitation-strengthened alloy with a cleaner microstructure that contributes to increased corrosion resistance. However, there is still a susceptibility for intergranular and inter-subgranular (IGC/IsGC). Because localized corrosion associated with coarse constituent particles is diminished due to alloy cleanliness, intergranular forms of attack are a larger factor in the corrosion profile of this alloy. The susceptibility to localized corrosion in AA2099 was characterized based on the attack morphology after exposure to various NaCl aqueous solutions. Alloy samples were subjected to a series of artificial heat treatments conducted at temperatures ranging from 120°C to 180°C for times ranging from 12 to 168 hours, corresponding to time and temperature ranges that are commensurate with commercial practice. The resulting microstructures were analyzed using scanning transmission electron microscopy (TEM), electron back-scattering, and diffraction methods, which characterized the precipitates formed during artificial aging. The formation of the strengthening phase T1 (Al2CuLi) was of particular interest due to its reported anodic behavior relative to the alloy matrix. This particle is prone to corrosion attack and plays a significant role in the evolution of localized corrosion mode and morphology depending on its location within the alloy. The results from the exposure experiments provided a map for the various heat treatments to identify when IsGC susceptibility will occur. Results showed that AA2099 went through several attack categories as samples were aged to under-aged (UA), peak-aged (PA), and over-aged (OA) conditions. The morphology in the cross section progre (open full item for complete abstract)

Committee: Rudolph Buchheit (Advisor) Subjects: Materials Science

MS, University of Cincinnati, 2010, Engineering : Mechanical Engineering

The functionality and reliability of Li-ion battery as major energy storage device has received more and more attentions from a wide spectrum of stakeholders including federal/state policymakers, business leaders, technical researchers, environmental groups and general public. Failures of Li-ion battery not only result in serious inconvenience and enormous costs, but also increase the risk of inducing catastrophic consequences. In order to prevent severe failure from happening and optimize the Li-ion battery maintenance schedules, breakthroughs in prognostics and health monitoring of Li-ion battery with emphasis on fault detection and correction, remaining-useful-life prediction and assist maintenance scheduling must be achieved. This paper firstly reviews recent research and development of health monitoring and prognostics for a variety of battery chemistries and summarizes the techniques, algorithms and models used for state-of-charge (SOC) estimation, current/voltage estimation, capacity estimation and remaining-useful-life (RUL) prediction. Based on the understanding of these researches, two data-driven approaches have been proposed to evaluate and predict the health status of Li-ion battery. The first approach, Gaussian mixture modeling, is an unsupervised learning method which doesn't require capacity as target. This is surely a pleasant feature since the capacity, though a good indicator of battery health, is neither easy nor cheap to acquire. Instead, the underlying pattern of input space is studied and the useful information (CV) extracted from it discloses the health status of Li-ion battery. The other approach, adaptive regressions, is a supervised learning method. Though targets are required this time, capacity is still not used. Instead, an important feature is found to have close relationship with capacity while easy to get in real world application. Based on this relevant feature, an adaptive framework for health assessment and prognostics is introdu (open full item for complete abstract)

Committee: Jay Lee PhD (Committee Chair); Samuel Huang PhD (Committee Member); Manish Kumar PhD (Committee Member) Subjects: Mechanical Engineering

Master of Sciences, Case Western Reserve University, 2008, Biochemistry

Chronic intermittent hypoxia (CIH) augments norepinephrine (NE) efflux to acute hypoxia in adult rat adrenal medulla (AM). Neuropeptide-Y (NPY) is shown to be co-stored with NE and facilitate its release from AM through NPY-Y1 receptor. This study examines if CIH alters NPY efflux from adult rat AM and, if so, by what mechanism(s), and the effect of NPY on CIH induced increase in blood pressure. NPY and NE effluxes were studied from ex vivo AM. Results of this study show that while acute hypoxia and acidic hypercapnia augments NPY efflux, isohydric hypercapnia and nicotine inhibited NPY efflux in CIH exposed AM. NPY, by facilitating NE efflux through NPY-Y1 receptor, contributes to CIH induced blood pressure raise. Antioxidant treatment restored the nicotine-evoked and inhibited acute hypoxia-evoked NPY efflux from AM of rats exposed to CIH suggesting mechanisms involving oxidant radicals are responsible for CIH induced alterations in NPY efflux.

Committee: GANESH KUMAR (Advisor) Subjects:

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

Li-ion batteries (LIB) have been spotlighted as a promising power source to replace traditional fuel gases owing to their high energy density, lightweight, and greenhouse gas emission free characteristics. Nevertheless, the catastrophic failure of the LIB is usually connected to safety issues, and the solutions must be addressed from the perspective of materials and designs. The representative materials for the current collectors in LIB are the commercial pure-grade aluminum (Al) and copper (Cu) foils because of their high electrical conductivities, electrochemical stabilities, and low density. However, they degrade during the multiple charge/discharge cycles when the applied voltage exceeds their corrosion potentials. The current flows generate the resistance heating during the charge/discharge cycles at the joint between the foil stacks and the lead tab, increasing the cell temperature. This accelerates the degradation of the foil and reduces the life cycle of the LIB. To reduce the electrical resistance, the increase in conductive area is desirable. Therefore, securing the large joint area with minimal weld discontinuities not only improves the mechanical properties helps but also impedes the resistance heating in LIB. The conventional resistance spot welding (RSW) process has not been widely used to produce the joint between the current collectors and the lead tab so far because of the high thermal, electrical conductivity and thinness of the Al and Cu weld stacks. These aspects generally lead to the smaller weld nugget size, and the sticking of the weld stacks to the electrodes. A recently developed hybrid joining process, known as ultrasonic-assisted resistance spot welding (URW), shows the great effects on increasing the weld nugget size as well as mechanical properties in various pairs of similar and dissimilar metal sheets by the microstructure modification. In the present study, multiple thin pure aluminum (Al) and copper (Cu) foils and tab stacks are (open full item for complete abstract)

Committee: Xun Liu (Advisor); Glenn Daehn (Committee Member); Avraham Benatar (Committee Member) Subjects: Engineering; Materials Science

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

Bachelor of Science (BS), Ohio University, 2024, Chemistry

Studying the topography and composition of materials' surfaces can give important insight into the chemical properties of that surface. Surface studies can be done both computationally or experimentally, but together they have a synergistic effect on the information learned and the research efficiency. This study aims to utilize both computational and experimental techniques to understand molecular systems that are used across different industries. The computational technique used primarily is density functional theory (DFT) and the experimental techniques for surface characterization are atomic force microscopy (AFM) and scanning electron microscopy (SEM). This study is characterizing surfaces for a sulfapyridine molecularly imprinted polymer and Li-metal batteries.

Committee: Martin Mohlenkamp (Advisor); Katherine L. Cimatu (Advisor) Subjects: Chemistry; Mathematics

Doctor of Philosophy, Case Western Reserve University, 2024, Chemical Engineering

Ionic liquids (ILs) are salts that are liquids at room temperature and are promising materials for use as electrolytes for lithium battery applications. The state-of-the-art organic carbonate (OC) electrolytes pose concerns due to their volatility, which, under abusive conditions, lead to the thermal runaway in Li-ion batteries (LIBs). Secondly, OCs are unreliable in secondary battery applications for Li-metal batteries (LMBs), as rapid dendrite growth on the Li-metal anode leads to short circuits. Contrary, ILs provide wide electrochemical windows, high lithium salt solubility, stable Li-metal anode cycling, and importantly, have negligible volatility, significantly reducing safety concerns. However, as ILs are comprised entirely of charged species, solvation and transport of Li-ions becomes complicated and sluggish. Typically, multiple IL anions solvate Li+ and result in Li-solvates that are negatively charged, leading to transport of Li+ in the wrong direction. Therefore, it is crucial to tune the properties of IL electrolyte to allow Li+ to free itself from its first solvation shell to improve its transport in the bulk, leading to improved electrochemical performance. This thesis work demonstrates the design of IL electrolytes comprised of multiple IL anions, asymmetric IL anions, and IL mixtures with hydrofluoroethers (HFEs) to improve upon Li-ion transport in conventional IL electrolytes and to mitigate the safety concerns of OC-based electrolytes. Specifically, a fundamental understanding of how Li+ is solvated in multicomponent IL electrolytes is examined through various spectroscopy techniques and simulations. Further, the solvation structure of Li+ is linked to its transport behavior by examining the solvation strength through ab initio calculations and measuring the transport properties including viscosity, diffusion coefficients, and Li+ transference. Thus, the structure-property relations are developed as a function of composition and supported (open full item for complete abstract)

Committee: Burcu Gurkan (Advisor); Robert Savinell (Committee Member); Rohan Akolkar (Committee Member); Shane Parker (Committee Member) Subjects: Chemical Engineering

Doctor of Philosophy, The Ohio State University, 2023, Mechanical Engineering

Lithium-ion (Li-ion) batteries adopted in electric vehicles (EVs) require significant increase in energy density (> 750 Wh/L) and reduction of costs to enable widespread commercialization. To address these challenges, R&D efforts have been directed towards (a) finding materials with high energy density (b) improving electrode design and (c) enhancing conductivity of the electrode materials. The former strategy involves implementing Nickel and Manganese based chemistries such as NMC, LNMO. In particular, the LNMO spinel cathode material is a promising material which provides high energy densities of 650 Wh/kg due to increased operating voltage of 4.75 Vvs Li/Li+. However, the increased voltage also accelerates oxidative decomposition reactions in the electrolyte and causes capacity fade in LNMO full cells paired with graphite anode. Using a composite binder can help passivate the carbon and cathode material surfaces against decomposition products from the electrolyte. Further, the composite binder also has the advantage of using water as the solvent making the process environmentally benign and cheaper compared with currently adopted N-Methyl 2-Pyrrolidone (NMP) solvent. The second strategy includes minimizing the use of inactive materials (e.g., current collectors and separators) and increasing the thickness of electrodes (> 250 µm), which in turn offers improved energy density with reduced cost. To achieve this an aqueous composite binder system is utilized which can sustain high thickness of electrodes while creating unique electrode architectures conducive to ionic and electronic conductivity. The third strategy utilizes a conductive polymer additive to create ion and electron conducting interfaces across the cathode material surface thereby providing better cycle and rate performance. The performance improvement in each of these strategies is demonstrated through electrochemical tests and their mechanisms are understood by utilizing several characterization tec (open full item for complete abstract)

Committee: Jung Hyun Kim (Advisor); Jay Sayre (Committee Member); Hanna Cho (Committee Member); Christopher Brooks (Committee Member) Subjects: Automotive Engineering; Automotive Materials; Materials Science; Mechanical Engineering

Doctor of Philosophy, University of Akron, 2022, Polymer Engineering

To develop advanced sustainable technologies for the energy needs of society, solid-state lithium-ion batteries are considered safer and more reliable. In those aspects, solid polymer electrolytes have been considered as one of the promising candidates. The present dissertation focuses on the exploration of solid polymer electrolytes with high ionic conductivity, wider electrochemical stability window, enhanced stretchability, and ion storing capabilities of herein-developed polymer electrolyte membranes. Chapter III of the dissertation deals with elucidation on the effect of different plasticizers viz. succinonitrile (SCN), ethylene carbonate (EC), and polyethylene glycol dimethyl ether (PEGDME) on ionic conductivity, electrochemical stabilities, and stability of plasticized PEMs against the lithium metal anode. Succinonitrile plasticized PEMs demonstrated higher ionic conductivity (~ 10-3 S/cm) with higher electrochemical stability (~ 5 V). On the other hand, ethylene carbonate-based PEMs exhibited higher stability against lithium metal. Lastly, the addition of lithium bis(oxalate) borate (LiBOB) additive to PEMs which resulted in improvement of stability against the lithium metal is discussed. To improve the stretchability of the polymer electrolyte membranes (PEMs), PEG-b-PPG-b-PEG-DA block copolymer was synthesized by the esterification reaction. As a result of the high molecular weight of the block copolymer resulting in a loosely crosslinked copolymer network, the PEM consisting of PEG-b-PPG-b-PEG-DA/EC/LiTFSI exhibited increased stretchability (> 100 % elongation at break) along with ionic conductivity of superionic conductor level (~10-3 S/cm). Furthermore, thermal, and electrochemical stability of PEMs along with the satisfactory room temperature charge/discharge cycling performance of half-cells were discussed in detail in Chapter IV. The investigation of superionic, wider electrochemically stable, ion storing, supercapacitve nature of polyethylene g (open full item for complete abstract)

Committee: Thein Kyu (Advisor); Xiong Gong (Committee Chair); Jae-Won Choi (Committee Member); Steven Chuang (Committee Member); Ruel McKenzie (Committee Member) Subjects: Energy; Engineering; Materials Science; Polymer Chemistry; Polymers

Master of Science, The Ohio State University, 2022, Mechanical Engineering

The major shift in the mobility industry towards electric vehicles requires the development of safer energy storage systems (ESS). Li-ion ESS has been at the forefront of automotive, aerospace, and stationary ESS for power backup applications, albeit it suffers from thermal instability issues, which prompts investigation into the thermal behavior of these systems. Thermal modeling of Li-ion batteries is an essential practice to understand the mechanisms behind heat generation and distribution, and cognizance of the thermal behavior is crucial to developing safer Li-ion batteries and optimal thermal management solutions. However, one of the most significant challenges associated with developing thermal models is parameter identification due to the unique layered construction of a Li-ion cell. The simplest thermal model for a Li-ion battery can require the identification of ten or more unknown parameters. The accuracy of the model depends on the accuracy of the parameter identification process. Thermal models also require electrical models to predict heat generation in the cell, which requires a plethora of unknown parameters to be identified to simulate the electrical behavior of the cell. The overall accuracy of predicted temperature and thermal distribution is dependent on the accuracy of both the electrical and thermal models. The parameter identification for thermal modeling requires extensive experimentation, with its challenges, such as heat propagation to the experimental setup and power cables connecting the cell to the battery cycler. The goal of the research presented in this thesis is to develop an innovative experimental setup, test procedures, and calibration strategy for a lumped-parameter thermal model with the aim of accurately estimating the temperature of the cell and the cell tabs. The research aims at developing a test bench capable of minimizing the heat transfer from the cell to the power cables and the ambient. Two thermal exper (open full item for complete abstract)

Committee: Marcello Canova (Advisor); Kim Jung Hyun (Committee Member); Matilde D’Arpino (Advisor) Subjects: Mechanical Engineering

Doctor of Philosophy, The Ohio State University, 2022, Chemistry

The ability to store energy in a scalable, profitable, and environmentally benign manner is a key challenge in the global transition to clean energy. Unfortunately, lithium-ion batteries (LIBs) and other conventional energy storage systems depend on metal-based electrode materials and the large-scale mining of metal ores, which is environmentally costly and ultimately unsustainable. Organic electrode materials (OEMs) offer an intriguing alternative to metal-based electrode materials, as OEMs benefit from abundant feedstocks, unparalleled synthetic modularity, and rich redox chemistry. However, reported OEMs lack the fast charging rates and long cycle lifetimes of metal-based electrode materials, likely due to low electrical conductivity and dissolution in battery electrolytes. To address these issues, we have focused on understanding fundamental relationships between the molecular structure of OEMs and battery performance, which can serve as design guidelines for the development of next-generation sustainable energy storage systems. Using benzoquinone as our OEM scaffold, we first investigated the impact of discrete synthetic modifications, such as incorporating thiazyl (-S=N-) moieties or hydrogen bonding motifs, to uncover new structure-performance trends for OEMs in LIBs. Through theoretical calculations and experimental studies, we established a positive correlation between non-covalent intermolecular interaction strength and performance for thiazyl and hydrogen bonding functional groups. In particular, we found that increasing the number of thiazyl S atoms or hydrogen bonding groups leads to stronger intermolecular interactions, resulting in enhanced charging rates and prolonged battery lifetimes. These works showcase molecular modification as a tool for systematically tuning battery performance, presenting two possible design strategies for improving conductivity and stability in future OEMs. Aside from LIBs, aqueous Zn-ion batteries (AZIBs) have become (open full item for complete abstract)

Committee: Shiyu Zhang (Advisor); Yiying Wu (Committee Member); Christopher Hadad (Committee Member); Christo Sevov (Committee Member) Subjects: Chemistry; Inorganic Chemistry; Organic Chemistry

Master of Science, The Ohio State University, 2021, Materials Science and Engineering

Lithium orthothioborate, Li3BS3, a promising superionic conductor for all-solid batteries, is experimentally revisited for the first time in nearly 20 years. The reaction of boron, sulfur, and lithium sulfide is explored via in-situ synchrotron x-ray diffraction (XRD) and pair distribution function (PDF). This has revealed an intermediate reaction at ~300°C of B and S forming B2S3, temperatures greater than 500°C required for Li2S to react significantly, and rapid crystallization of Li3BS3 at 370°C, far below its estimated melting temperature between 650°C and 675°C. Coefficients of thermal expansion (CTEs) were determined from the contraction of the unit cell, which occurred anisotropically. Several synthetic routes were explored, and products were characterized with ex-situ XRD, PDF, Raman spectroscopy, electrochemical impedance spectroscopy (EIS) and differential scanning calorimetry (DSC). This revealed important practical considerations for working with this material and to minimize impurity phases, which negatively impact ionic conductivity. Water quenching from a melt yielded a material with increased disorder and an activation energy for Li+ conductivity of 197 meV, the lowest reported for this material in either vitreous or crystalline form. Other samples also had lower activation energies than expected, possibly due to faster reaction times than previous studies.

Committee: Jinwoo Hwang (Committee Member); Vicky Doan-Nguyen (Advisor) Subjects: Energy; Engineering; Experiments; Inorganic Chemistry; Materials Science; Sustainability

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

As demand for sustainable and clean transportation continues to increase, matching the refueling capabilities of Electric Vehicles (EVs) to conventional vehicles is a major research and development challenge. To accelerate the adoption of EVs, higher power fast charging must be implemented. Currently, fast charging a battery pack presents several barriers, primarily with respect to cell longevity and safety. One of the main durability issues is caused by lithium plating, a degradation phenomenon that may occur when charging a cell at high C-rate or low temperature conditions. Plating can significantly reduce a cell cycle life and poses serious safety concerns due to potential thermal runaway from internal shorting. For these reasons, it is important to predict the root causes and mechanisms associated to Li-plating and mitigate its effects to prevent the chemical and mechanical degradation of cells during fast charging. This Dissertation seeks to develop physics-based modeling techniques and integrate them with novel experimental testing procedures to predict the cell behavior associated with lithium plating. Fast charge testing was performed with the goal of measuring cell behavior at different conditions by varying charging C-rate, cutoff current, and temperature. The results of this investigation were used to develop a method to detect the onset of lithium plating using specific indicators of the reaction in the collected data. Starting from the test results, a physics-based model predicting the degradation induced by fast charging was created and integrated into two different electrochemical models. In doing so, the specific problem of improving the accuracy of electrochemical models in predicting the cell voltage response during fast charging conditions was investigated. The methods developed in this Dissertation for integrating physics-based models and experimental analysis provide fundamental guidance to conduct a thorough investigation into the factors (open full item for complete abstract)

Committee: Marcello Canova (Advisor); Giorgio Rizzoni (Committee Member); Jung-Hyun Kim (Committee Member) Subjects: Mechanical Engineering

Master of Sciences, Case Western Reserve University, 2021, EMC - Mechanical Engineering

At high temperatures, polymer separators in conventional Li-ion Batteries are prone to melt, fail to separate the electrodes, and cause internal short circuits. A PVDF-based hybrid electrolyte with Li1.3Al0.3Ti1.7(PO4)3 (LATP) and Al2O3 filler, prepared with NMP/glycerol dual solvents by slurry coating is reported in this thesis. The effects of fillers and glycerol on the ionic conductivity of the hybrid electrolyte membrane are studied. It was found that the use of glycerol and Al2O3 nanoparticles can increase the hybrid electrolyte's ionic conductivity. The dual-solvent prepared sample with a specific composition of PVDF/LATP/Al2O3=3/6/1 shows the highest ionic conductivity of 1.39 mS/cm, which is 30% higher than the sample without Al2O3. The membrane also exhibits better thermal stability compared to a Celgard 2325 commercial polymer separator. Li//Li symmetrical cell assembled using the prepared membrane shows excellent stability. In NMC half-cell cycling tests, capacity retention of 92.8% and 92.1 % are achieved on 50 cycles at 0.5 C and 1 C, respectively.

Committee: Chris Yuan (Advisor); Bo Li (Committee Member); Burcu Gurkan (Committee Member) Subjects: Engineering

Doctor of Philosophy, Case Western Reserve University, 2020, Chemical Engineering

High-energy density batteries are essential for powering future electric vehicles (EVs) and electric aircraft. These technologies are limited by the capacity of their batteries. Enabling high-specific energy batteries could make longer-range electric vehicles and electric aircraft a reality. The Li-metal anode offers the highest theoretical specific energy among practically available anode materials. However, secondary Li-metal anodes experience capacity loss and safety hazards caused by the growth of dendrites on the anode surface during charging. After four decades of research on Li-metal batteries, rechargeable Li-metal anodes that do not evolve dendrites are still not commercially available. Understanding the physical causes and mechanisms of dendritic Li electrodeposition, in order to develop commercial Li-metal batteries, motivates the present work. It is shown herein that solid-state transport limitations within a dynamic solid electrolyte interphase (SEI) are dominant in controlling the time when Li dendrites first form. Chronopotentiometry and optical imaging provide experimental observations for when dendrites first appear on a Li electrode. Dendrite onset time is shown to increase with increasing temperature and decrease with increasing current density and initial SEI thickness. These phenomena are shown to be due to the onset of diffusion limitations brought on by a thickening SEI. Electrochemical impedance spectroscopy (EIS) provides evidence for SEI growth and enables estimation of the SEI growth rates during Li electrodeposition. These experiments guide the development of an analytical model that explains mechanistically how transport limitations within the SEI control the onset time of dendrite growth during Li electrodeposition. The model also provides predictions of Li dendrite onset times. These predictions agree qualitatively with the observed effects of current density, initial SEI thickness, temperature, and pulsing. Finally, it is shown th (open full item for complete abstract)

Committee: Rohan Akolkar PhD (Advisor); Uziel Landau PhD (Committee Member); Donald Feke PhD (Committee Member); Alp Sehirlioglu PhD (Committee Member) Subjects: Chemical Engineering