<p>Li-ion batteries (LIBs) are currently pervasive across portable electronics and electric vehicles and are on the ascent for large-scale applications such as grid storage. However, commercial LIBs based on intercalation chemistries are inching toward their theoretical energy density limits. Consequently, the rapidly growing demands of energy storage have necessitated a recent renaissance in exploring battery systems beyond Li-ion chemistry. Next-generation batteries that utilize Li metal as the anode can improve the energy density and power density of LIBs. Despite the theoretical promise, the commercialization of metal-based batteries requires overcoming several hurdles, stemming from the unstable nature of Li in liquid electrolytes. Upon repeated charging, the metal anode undergoes unrestricted growth of dendrites, devolving to a thermal runaway in extreme circumstances. By replacing the organic liquid electrolyte with a non-flammable solid electrolyte, solid-state batteries (SSBs) can potentially provide enhanced safety attributes over liquid electrolyte cells. Upon pairing of solid electrolytes with a Li metal anode, such systems present the unique possibility of engineering batteries with high energy density and fast charging rates. However, there are a number of technical challenges and fundamental scientific advances necessary for SSBs to achieve reliable electrochemical performance. The formation of dendritic morphologies during charging and the loss of active area at the anode-electrolyte interface during discharging are two critical limitations that need to be addressed.</p> <p>In this thesis, the morphological stability of the Li metal anode is examined based on the mechanistic interaction of electrochemical reaction, ionic transport and surface self-diffusion, that is further dependent on aspects including the thermal field and electrolyte composition. The origin of electrochemical-mechanical instability and metal penetration due to heterogeneities in solid-state electrolytes such as grain boundaries will be analyzed. The phenomenon of contact loss at solid-solid interfaces due to the competing interaction between electrochemical dissolution and Li mechanics will be studied. Lastly, the mechanistic attributes governing the thermal stability of solid-solid interfaces in solid-state batteries will be examined. Overall, the dissertation will focus on understanding the fundamental mechanisms underlying the evolution of solid-liquid and solid-solid interfaces in energy storage and derive potential design guidelines toward achieving stable morphologies in metal-based batteries.</p>

When an anode electrode potential is larger than the lowest unoccupied molecular orbital (LUMO) of the electrolyte, Li-ions and electrolyte molecules will participate in reduction reactions on the anode surface and form a solid electrolyte interface (SEI) layer. Active Li-ion consumption in the formation reactions is the main source of capacity loss (>50) and ageing in Li-ion batteries (LIBs). Due to the fast-occurring and complex nature of the electrochemical processes, conventional experimental techniques are not a feasible approach for capturing and characterizing the SEI formation phenomenon. The lack of experimental data and consequently the absence of potential parameters for crystal structures in this layer makes molecular dynamics~(MD) simulations inapplicable to it. Also, due to the multi-component multi-layer structure of the SEI, the smallest system representing an SEI layer is too large for employing the principles of quantum mechanics~(QM), that traditionally work with much smaller system sizes. Addressing this, this thesis presents a novel computational framework for coupling QM and MD calculations to simulate a system with the size limits of MD simulations independent of the experimental data. The QM evaluates sub-atomic properties such as energy barriers against diffusion and employs seven new algorithms to estimate potential parameters as the input of the MD simulations. Then MD simulations forecast SEI's properties including density, Young's Modules, Poisson's Ratio, thermal conductivity, and diffusion coefficient mechanisms. The output of the QM and MD calculations are employed to develop two macro-scale mathematical models for predicting battery ageing and battery performance, incorporating the impact of the SEI layer in addition to the cathode, anode, and separator parts. Finally, the results obtained have been validated with respect to the experimental data in different operational conditions. / Thesis / Doctor of Philosophy (PhD) / The limited lifespan of expensive batteries is the main obstacle to electrification of the transport sector, despite its necessity for addressing the current environmental issues. Li+/electrolyte reduction on the electrode surface is responsible for more than 50% of capacity loss and the consequent ageing is a complex and fast-occurring phenomenon (few ns) that cannot be easily resolved using conventional experimental and computational techniques. This thesis presents the development of some computational frameworks and demonstrates their employment to investigate this phenomenon from a multi-scale perspective, i.e., from a few electrons to an entire battery length scale, with the operating cycles ranging from a few ps to several months, employing Quantum Mechanics, Molecular Dynamics, and Macro-Scale Modeling. The frameworks have been successfully validated with respect to experimental data from the literature and have been applied successfully to highlight the parameters that impact ageing in batteries. The findings presented in this thesis can be used as the base for further research on next-gen durable batteries with liquid and solid-state electrolytes.

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Food is a universal human necessity, yet food often serves more than a biological purpose as it informs individual and communal identities, and even facilitates memory. This thesis explores personal memory, the development of identity, and an almost reverential connection to nature in several food poems by Li-Young Lee in Rose (1986) and Behind My Eyes (2008). Born in 1957, Lee has been writing poetry since he was young, studying under Gerald Stern in the late 1970s, and he is known for writing sublime, transcendent yet incredibly accessible and expressive poetry. This thesis gives an overview of food studies and establishes food in Lee’s poems — principally fruit, shared meals, and lonely meals — as the central image, signifier, or as Roland Barthes might call it, the myth that allows the speaker of these poems to metaphorically fulfill the aphorism, “you are what you eat.”

The applications of Li-ion batteries in the electronics and vehicle industry is increasing at a very rapid pace. This is primarily due to superior properties such as high specific energy storage and power as well as wider operation temperature ranges. Additional potential for improved properties is connected to capacity losses with time and the thereby resulting limitations of lifetime of batteries. The lifetime of a battery is strongly related to the mechanical and chemical degradation of the active material of electrodes during repeated electrochemical reactions at charging and discharging. To identify this phenomenon from a mechanical perspective, the mechanical properties of the electrode active layers should be characterized. Additionally, with the aid of mechanical properties, realistic electro-chemo-mechanical models should be developed to comprehend the mechanisms causing capacity fade. In the first part of this thesis, macroscopic material properties of the active layers of Li-ion battery electrodes were measured with a unique bending test technique. Contrary to methods previously used; it is capable to overcome the challenges that were encountered in other traditional testing techniques. In papers 1 and 2 this bending test technique (U-shaped bending test), is used to characterize the elastic and viscoelastic behavior of NMC cathodic and graphite anodic active layers, respectively. By using single-sided thin electrode specimens in U-shape bending tests, it was possible to distinguish tensile and compressive elastic and viscoelastic behavior of the electrode active materials. The tensile Young’s moduli of cathodic and anodic active layers are found as 0.73 GPa and 1 GPa, respectively. On the other hand, the compressive Young’s moduli show a stiffening behavior at increasing strains. Stiffnesses between 1.3 GPa and 2.8 GPa for the cathodic active layer, and between 1 GPa and 3.8 GPa for the anodic active layer were recorded. This compressive behavior of the electrode active layers is expected as a result of the porous nature of the materials. In addition, the viscoelastic behavior of the electrode active layers is expressed through Prony series. It was observed that the behavior can be described by a short term (minutes) and a long term (hours, days) relaxation. In paper 3, a statistical representative volume element is introduced to predict the elastic properties of a dry cathodic electrode active layer. A porous cathodic electrode active layer that is composed of NMC active particles and polymeric binder material with conductive carbon additives is modeled as a face-centered-cubic structure. Several particle-binder and particle-particle interaction conditions are repeated 50 times with random orientations. Based on the statistics for each interaction case, Young’s modulus is estimated. The results show a good agreement with the experimental findings from Paper 1. Furthermore, particle-particle and particle-binder contact force distributions are calculated for 3% of particle swelling. The characteristics of the force distributions are correlated with the typical material failures in the active layer such as particle cracking and binder debonding. The statistical data obtained here are also used to improve an analytical model that was previously derived to estimate the elastic properties of active porous layers. The analytical model, complemented by the statistical results, showed an excellent agreement with the finite element simulations. / <p>QC 230124</p>

The purpose of this study was to determine the influence of IQ on subtypes of sociable and withdrawn behaviors in children with language impairment (LI). Research has suggested that children with LI are more likely to experience difficulty with social interaction than their typically developing peers (Brinton & Fujiki, 1999; Rice, 1991). The Teacher Behavior Rating Scale (Hart & Robinson, 1996) was used to compare sociable and withdrawn behaviors in 19 children with LI and 19 children with typically developing language. IQ scores for each participant were obtained by administering the Universal Nonverbal Intelligence Test (Bracken & McCallum, 2003). These scores were used as a covariate in group comparisons of sociable and withdrawn behaviors. Comparisons indicated that classroom teachers rated children with LI as displaying more withdrawal and less sociable behaviors than typically developing children even when IQ was controlled.

This work presents novel modeling and experimental techniques that provide insight into liquid-phase mass transport and electron transfer processes in lithium-ion batteries. These included liquid-phase ionic mass transport (conduction and diffusion), lithium diffuion in the solid phase and electronic transport in the solid phase. Fundamental understanding of these processes is necessary to efficiently design and optimize lithium-ion batteries for different applications. To understand the effect of electrode structure on the electronic resistance of the cathode, we tested power performance of cathodes with combinations of three different carbon conductivity additives: vapor-grown carbon fibers (CF), carbon black (CB) and graphite (GR). With all other factors held constant, cathodes with a mixture of CF+CB were found to have the best power-performance, followed by cells containing CF only and then by CB+GR. Thus, the use of carbon fibers as conductive additive was found to improve the power performance of cells compared to the baseline (CB+GR). The enhanced electrode performance due to the fibers also allows an increase in energy density while still meeting power goals. About one-third of the available energy was lost to irreversible processes when cells were pulse-charged or discharged at the maximum rate allowed by voltage-cutoff constraints. We developed modeling and experimental techniques to quantify tortuosity in electrolyte-filled porous battery structures (separator and active-material film). Tortuosities of separators were measured by two methods, AC impedance and polarization-interrupt, which produced consistent results. The polarization-interrupt experiment was used similarly to measure effective electrolyte transport in porous films of cathode materials, particularly films containing lithium iron phosphate. An empirical relationship between porosity and the tortuosity of the porous structures was developed. Our results demonstrate that the tortuosity-dependent mass transport resistance in porous separators and electrodes is significantly higher than that predicted by the oft-used Bruggeman relationship. To understand the dominant resistances in a lithium battery, we developed and validated a model for lithium iron phosphate cathode. In doing so we considered unique physical features of this active material. Our model is unusual in terms of the range of experimental conditions for which it is validated. Various submodel and experimental techniques were used to find physically realistic parameters. The model was tested with different discharge rates and thicknesses of cathodes, in all cases showing good agreement, which suggests that the model takes into account physical realities with different thicknesses. The model was then used to find the dominant resistance for the tested cathodes. The model suggests that the inter-particle contact resistance between carbon and the active-material particles was a dominant resistance for the tested cathodes.

The purpose of this study was to determine whether children with specific language impairment (SLI) are more or less variable than children with typically developing language. In addition, the within child variability for children with SLI was analyzed to consider how heterogeneity influenced identification of areas of linguistic strengths and weaknesses in this population. Fifty seven children with SLI, 7:0–11:0, and fifty seven of their peers with typically developing language were assessed using five subtests and a composite language score from the Comprehensive Assessment of Spoken Language (CASL) (Carrow-Woolfolk, 1999). The children with typically developing language were significantly more variable as a group than the children with SLI. The heterogeneity of the children with SLI did not allow for the creation of subgroups based on language strengths and weaknesses.

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.

A large number of Li-ion batteries used today will reach their End-Of-Life (EOL) in a few years. After their EOL, the recovery of their precious elements is required. By applying physical separation, a fraction with fine particle size is left behind which is known as Black Mass (BM). BM is rich in LIB precious materials, including Li metal oxides and graphite. In this study, pyrometallurgical recycling of BM is investigated. In the first step, the BM high-temperature transformations are being studied, focusing on reducing Li metal oxides, Li evaporation, and F removal. In the second step, Fe and Cu oxides are added to the BM to investigate how the graphite remaining in the BM can be used as a reducing agent and form alloys with Co and Ni. The use of mechanical activation as a mean to improve the kinetics of the reactions and the efficiency of the reduction reaction was also studied. To model the experiments in this study, thermodynamic softwares (FactSage and HSC) were also employed.