Next generation lithium-ion batteries will take on a wide variety of roles to meet the increased requirements from growth in consumer electronics, electric vehicles, and utility storage for integrating intermittent renewable (solar and wind) power sources. The cost per watt-hour of commercial batteries have shown incremental improvement due to improved manufacturing design, though drastic increases in energy and power density are needed to satisfy projected demand. Solid-state electrolytes (SSE) are explored due to their potential to improve energy and power density through enabling alkali metal anodes, while mitigating safety and temperature stability concerns associated with conventional liquid electrolyte lithium-ion batteries. However, there are still significant scientific and engineering hurdles before the full potential of SSEs can be realized: primarily performance degradation from chemical and mechanical interfacial instability.

We enable the use of solid-state thin film battery materials and devices as a model system for fundamental studies of bulk and interface properties because of their well-defined geometry and controlled chemical composition, eliminating any effects from polymeric binder or conductive agents. In this thesis, we explore the structural, mechanical, and electrochemical properties of thin film electrolytes amorphous lithium lanthanum titanate (a-LLTO) and lithium phosphorous oxynitride (LiPON) along with the fabrication of thin film batteries with various electrode chemistries. Using these devices we develop focused ion beam (FIB) as a technique to fabricate electrochemically active nanobatteries that enables in situ analysis in a FIB or transmission electron microscope (TEM) to couple local structural, morphological, and chemical phenomena. Further, one key advantage of SSEs is the potential to use a lithium metal anode. However, characterization of Li and Li/electrolyte interfaces is limited due to its intrinsic high chemical reactivity, low thermal stability, and low atomic number, making it prone to contamination and melting. Therefore, we demonstrate the ability of cryogenic focused ion beam (cryo-FIB) to process and characterize electrochemically deposited Li and Li metal based solid-state thin film devices.

The hole-transporting layer currently remains one of the obstacles preventing large-scale implementation of perovskite solar cells (PSCs). By using electrochemical polymerization to deposit the conducting polymer, polythiophene, onto perovskite, the major limitations prevalent in current methods can be avoided. The technique allows for uniform thickness of the deposited layer and utilizes cheap reagents that matches the low cost of the perovskite layer. Polythiophene films were grown and characterized by FTIR, SEM, EDX, and UV-Vis in order to gain an understanding of how growth conditions affected film properties. Based on these results, I developed a method for large-area deposition that is compatible with industrial scale solar cell production. This method was used to fabricate PSCs with polythiophene as the hole-transporting layer in inverted architecture. Investigations into in situ electropolymerized polythiophene onto perovskite was also explored

With the rapid depletion of conventional energy sources based on fossil fuels and increasing energy demand, sustainable and renewable energy technologies, such as solar, wind, hydroelectric power, have been drawn worldwide attention in energy-based economics. Because of their uncontrollable and intermittent nature, large-scale high- power electrical energy storage (EES) system is required to increase reliability of renewable energy resources. Among various energy storage systems, lithium-ion batteries (LiBs) are considered as the most important rechargeable energy storage system. However current LiB technology is still inadequate to compete against the conventional fossil fuels and implement in the large-scale applications: Key questions are cost, energy density, cycling life, and safety issues. In the first part of this dissertation, rare-earth-free permanent magnets (PMs) are intensively studied. Our innovative approach, using polyol process, developed nanostructured cobalt carbide (NCC) consisting of an assembly of Co2C and Co3C nanoparticles. The resulting material exhibits an energy product of greater than 15.84 MGOe at room temperature before compaction, which is confirmed through vibrating sample magnetometer (VSM) and first order reversal curves (FORCs). An understanding of the formation mechanism, using in situ time-resolved x-ray absorption spectroscopy (XAS), and the correlation between phase contributions to the properties are described in detail. Our success in the development of rare-earth-free PMs may provide a cost- effective and sustainable platform for clean technology applications. Although the performances of LiBs have been drastically improved, the limit in terms of the energy density and material stability still needs to be resolved. In the second part, high-voltage cathode materials, spinel LiNi0.5Mn1.5O4 (LNMO) and olivine LiCoPO4, are investigated to understand the influence of synthetic conditions of polyol synthesis on their electrochemical properties and structural stabilities upon cycling. High- angle annular dark field scanning transmission electron microscopy (HAADF-STEM) and X-ray photoelectron spectroscopy (XPS) allow us to determine the evolution of phase transformation accompanied with the migration of transition metal (TM) ions at the surface and electrode/electrolyte interfaces.

The Li-ion battery is one of the best rechargeable energy storage techniques due to its exceptional high energy density and long cycle life. It has dominated the portable electronic industry for the past 20 years and is going to be applied for large scale energy storage. However, concerns over limited lithium reserve and rising lithium costs have arisen, therefore Na-ion batteries are being considered as the alternative for grid storages.

In this thesis, Na2Ti3O7 is first investigated as anode materials for Na-ion batteries. By carbon coating, the cyclability and coulombic efficiency are significantly enhanced for Na2Ti3O7. The self-relaxation behaviour for fully intercalated phase, Na4Ti3O7, is shown for the first time, which results from structural instability as suggested by first principles calculation. Another SnS2-reduced Graphene Oxide (rGO) composite material is investigated as an advanced anode material for Na-ion batteries, which can deliver a reversible capacity of 630 mAh g-1 with negligible capacity loss and exhibits superb rate performance. The energy storage mechanism of it and the critical mechanistic role of rGO are revealed in detail.

On the cathode side, we introduce a novel layered oxide cathode material, Na0.78Ni0.23Mn0.69O2. This new compound provides remarkable rate and cycling performances owning to the elimination of the P2-O2 phase transition upon Na deintercalation. The first charge process yields an abnormally excess capacity which has yet to be observed in any other P2 layered oxides. It is proposed that part of the charge compensation mechanism during the first cycle takes place at the lattice oxygen site, resulting in a surface to bulk transition metal gradient. Atomic layer deposition (ALD) is known to improve the cycling performance, coulombic efficiency of batteries, and maintain electrode integrity for LIBs. Therefore we examine carefully the effect of Al2O3 ALD coating to P2 electrode materials. X-ray photoelectron spectroscopy (XPS) is used to elucidate the cathode electrolyte interphase (CEI) on ALD coated electrodes, which clearly reveal the effectiveness of the ALD coating. We believe that by optimizing and controlling the materials surface, Na layered oxide material with higher capacities can be designed.

The perovskite solar cell (PSC) is a photovoltaic device. With the tunable bandgap, long carrier diffusion length, and low exciton binding energy of various perovskite materials, power conversion efficiency (PCE) of 22.7% has been achieved. Though PSCs have high energy conversion efficiencies and low manufacturing cost, low device stability limits its further application and commercialization.

One of the major bottlenecks hindering the improvement of device stability is the interaction of components in the hole transport layer: lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and 4-tert-butylpyridine (tBP). LiTFSI is hygroscopic and accelerates perovskite decomposition. tBP, which evaporates easily, is corrosive to perovskite materials. Previous research has assumed that tBP and LiTFSI have similar working mechanisms in perovskite solar cells as what they performed in solid-state dye-sensitized solar cells (ss-DSSCs). However, due to the different device configurations and functional layers, it is necessary to understand the actual functions of these hole transport layer components in PSCs in order to further improve device stability and efficiency.

In our study, a spectrum-dependent mechanism for the oxidation of hole transport material 2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenylamine)-9,9′-spirobifluorene (Spiro-OMeTAD) with LiTFSI in PSCs was proposed. The perovskite layer plays different roles in the Spiro-OMeTAD oxidization for various spectral ranges. Regarding tBP, we confirmed its role as a HTL morphology controller in PSCs for the first time. Our observations suggest that tBP significantly improves the uniformity of the HTL and avoids accumulation of LiTFSI. We also observed the formation of tBP-LiTFSI complexes in PSCs. These complexes in PSCs can alleviate the negative effects of tBP and LiTFSI while maintaining their positive effects on perovskite materials. Consequently, a minor change of tBP:LiTFSI ratio displays huge influences on the stability of perovskite. As a result, the PSCs fabricated with our suggested tBP:LiTFSI ratio have decreased efficiency variation with enhanced device stability. Our understanding of the functions of these hole transport layer components and perovskite on a molecular level paves the way for further improvements to PSCs performance.

Lithium (Li) ion batteries have been successfully commercialized under decades of development and made a great impact as energy storage devices for electronics industries. The demand keeps increasing and expands to larger areas like grid storage and electric vehicles, which calls for higher energy density, longer cycle life, and wider operation conditions. However, there have been little changes in electrolyte compositions since its commercialization and the balanced-properties of the conventional electrolytes can’t meet the requirements for next-generation electrodes, such as Li-metal anode, high-voltage cathodes.

Herein, we design and develop a novel electrolyte system from a unique direction. The use of molecules that are gases under standard conditions is liquefied under moderate pressure to form liquefied gas electrolyte for the first time. Combing the superior physical and chemical properties, the liquefied gas electrolytes show a wide potential window of stability and impressive performance in extended temperature ranges. Electrolytes using difluoromethane (DFM) and fluoromethane (FM) demonstrate excellent performance in a wide temperature range for electrochemical capacitor and 4-volt lithium-ion battery, respectively.

Comprehensive approaches are applied to have a deeper understanding of liquefied gas electrolytes and further improve the overall performance. Tetrahydrofuran is first introduced as a cosolvent to improve the salt solubility and conductivity. The unique solvation structure and stable solid electrolyte interface enable improved Li-metal coulombic efficiency and rate capability in a wide temperature range down to -60°C. Besides, there are demands to further expand the upper-end boundary of both voltage and temperature window of liquefied gas electrolytes. Therefore, in a separate study, we formulate liquefied gas electrolytes using acetonitrile as a cosolvent and a higher salt concentration of 1.2 M for 4.5 V Li-metal batteries in a wider temperature range (-78~+75°C). Possibilities of using other liquefied gas solvents for Li-ion batteries are also been explored. A mixture of liquefied solvents is selected to improve safety. The electrolyte shows unique properties on fire extinguishing and one step recycling with excellent electrochemical performance.

Lithium ion batteries have become one of the most important rechargeable energy storage devices used in our modern society today. As the demand for such devices shift from portable electronics to electric vehicles and large scale storage in order to utilize energy sustainably, ever increasing energy densities both in terms of weight and volume are needed. To satisfy this demand, lithium ion batteries utilizing solid state electrolytes show promise of a new paradigm shift in energy storage technologies. The introduction of solid state electrolyte could, in principle, yield many advantages over conventional lithium ion batteries. Foremost, lithium metal can be used as the anode along with a high voltage cathode to boost energy density. Secondly, removal of flammable liquid electrolyte greatly improves the inherent safety of the battery.

We focused on using Focused Ion Beam (FIB) nano-fabrication technique to prepare Transmission Electron Microscopy (TEM) samples of all-solid-state batteries produced through physical vapor deposition techniques. The particular full cell chemistry of lithium cobalt oxide (LiCoO2) as cathode, amorphous silicon (a-Si) as anode, and lithium phosphorus oxynitrdie (LiPON) as electrolyte was used for investigations. Through analysis of TEM images and electron energy loss spectroscopy (EELS), important interfacial phenomena were observed at the anode-electrolyte interface and the cathode-electrolyte interface. Overcharging of the anode resulted in accumulation of lithium at the anode-current collector interface and interdiffusion of phosphorus and silicon atoms at the anode-electrolyte interface.

Furthermore, we developed a unique methodology using FIB fabrication techniques to prepare electrochemically active TEM samples of all-solid-state nanobatteries that can be galvanostatically charged in the FIB or TEM. This new methodology enabled in situ TEM observations of a previously undiscovered interfacial layer between the LiCoO2 cathode and LiPON electrolyte. This interfacial layer is composed of a highly disordered rocksalt like cobalt oxide phase that is oxidized and forms lithium oxide species during in situ charge. Additionally, electrochemically cycling at elevated temperatures (80 °C) causes further decomposition of the cathode layer decreasing the overall capacity and increasing interfacial impedance of the cell. These results indicate that proper engineering of electrode-electrolyte interface is essential for the performance of all-solid-state batteries.

The energy storage and conversion is one of the key issues for human beings to live sustainably on earth since our living environment has been deteriorating with the development of industrialization. We can alleviate the waste of energy consumption and corresponding environmental pollutions by storing and converting energy efficiently. The electrochemical cells are drawing considerable attention recently as a promising solution. In this thesis, electrode materials for Li-ion batteries and aqueous electrochemical cells are studied, focusing on the electrochemical and thermodynamic aspects.

First, transition metal difluorides, MF2 (M = Fe,Ni, and Cu) are explored. It is found that the conversion-reaction voltage is associated with the size of the converted metal nanoparticles. The surface energy of metal nanoparticles reduces the reaction energy, which decreases the conversion-reaction voltage. In addition, CuF2 electrodes are rechargeable when it is coated with NiO. NiO alleviates Cu dissolution into an electrolyte and enhances the cyclability of CuF2.

Second, Zn/β-MnO2 alkaline battery is studied as a promising rechargeable energy storage of high capacity. The nano-sized β-MnO2 cathode in the alkaline electrolyte of LiOH and KOH exhibit the average discharge capacity of 280 mAh g-1 over the first 100 cycles. It is found that the β-MnO2 transforms through proton intercalation and conversion reactions. The capacity is improved further with an addition of 4% mole fraction Bi2O3 in the nanosized β-MnO2.

Third, density functional theory (DFT) calculations are conducted for Li4Ti5O12 (LTO), its Gadolinium (Gd)-doped, and lithiated phases. The density of states (DOS) of LTO exhibits the property of an electrical insulator, however Gd-doped LTO is an electrical conductor which enhances the electrochemical performance. In addition, the formation energy of lithiated LTO phases is calculated to understand the reaction mechanism of LTO upon lithiation. The calculated results show that the lithiation proceeds by the two-phase reaction and there is no intermediate phase between two end phases: Li4Ti5O12 and Li7Ti5O12.

Lastly, oxygen evolution reaction (OER) on YBaCo4O7 (110) is investigated by DFT calculations. The results indicate that OER can be easily activated by YBaCo4O7 (110) due to its low overpotential. The free energy diagram exhibits the oxidation from O* to OOH*, which is the rate-determining step.

Chlamydiae replicate intracellularly in a vacuole called an inclusion. Chlamydial-infected host cells are protected from mitochondrion-dependent apoptosis, partly due to degradation of BH3-only proteins. The host-cell adapter protein 14-3-3 beta can interact with host-cell apoptotic signaling pathways in a phosphorylation-dependent manner. In Chlamydia trachomatis-infected cells, 14-3-3 beta co-localizes to the inclusion via direct interaction with a C. trachomatis-encoded inclusion membrane protein. We therefore explored the possibility that the phosphatidylinositol-3 kinase (PI3K) pathway may contribute to resistance of infected cells to apoptosis. We found that inhibition of PI3K renders C. trachomatis-infected cells sensitive to staurosporine-induced apoptosis, which is accompanied by mitochondrial cytochrome c release. 14-3-3 beta does not associate with the Chlamydia pneumoniae inclusion, and inhibition of PI3K does not affect protection against apoptosis of C. pneumoniae-infected cells. In C. trachomatis-infected cells, the PI3K pathway activates AKT/protein kinase B, which leads to maintenance of the pro-apoptotic protein BAD in a phosphorylated state. Phosphorylated BAD is sequestered via 14-3-3 beta to the inclusion, but it is released when PI3K is inhibited. Depletion of AKT through short-interfering RNA reverses the resistance to apoptosis of C. trachomatis-infected cells. BAD phosphorylation is not maintained and it is not recruited to the inclusion of Chlamydia muridarum, which protects poorly against apoptosis. Thus, sequestration of BAD away from mitochondria provides C. trachomatis with a mechanism to protect the host cell from apoptosis via the interaction of a C. trachomatis-encoded inclusion protein with a host-cell phosphoserine-binding protein.