Thesis (Ph. D.)--University of Wisconsin--Madison, 1970. / Typescript. Vita. Description based on print version record. Includes bibliographical references.

Lithium batteries play a critical and indispensable role in our modern way of life, enabling portability and further miniaturization of several technologies that would otherwise be either stationary or simply not possible. As one of the most important technologies of the twenty-first century, our civilization enjoys the immense benefits it currently offers, and that it stands to offer in the decades to come. The existence of current systems can be traced back to a compromise made during the initial stages of lithium battery commercialization, when energy content had to be sacrificed for safety, reliability and performance, due to the instability of the lithium metal anode when used with flammable, liquid electrolytes. Since then, academia and industry have embarked on a decades long quest to overturn this compromise, and recover that which has been lost. Liquid electrolytes and graphite anodes are largely responsible for the great benefits of high power that lithium batteries afford us, but achieving greater energy densities, safety and performance will require different battery materials; the question is which ones, the answer to which is a task complicated by the delicate balance of many factors. Current battery research has sought to develop solid electrolytes to do away with the flammability and explosion issues tied with liquid electrolytes, either in the form of polymer or inorganic electrolytes. Polymer electrolytes are flexible and easy to manufacture, but suffer from low ambient temperature conductivities and performance, while inorganic electrolytes have high conductivities and mechanical moduli, but are brittle and suffer from poor interfacial properties, including limited thermodynamic stability against electrode materials, in many cases. The ipossibility of combining together polymer and inorganic electrolyte materials, to give hybrid electrolytes, is attractive, but issues such as component compatibility, ionic transport across interfaces within the material, and the issues inherited from the parent materials, have frustrated efforts to find a successful hybrid electrolyte. The lack of a clear, superior hybrid system prevents focused efforts from being centered around a narrow set of systems, making it more difficult to identify additional clues that can inform current known requirements for hybrid systems. In this present work, systematic efforts to characterize first the individual components of novel hybrid systems, and subsequently to characterize model systems and complete hybrid systems, are described.Chapter 1 provides a framework of principles governing lithium batteries, as well as the current issues plaguing lithium battery research, while Chapter 2 lists the materials, methods and equipment used in this work. Chapter 3 focuses on identifying a suitable organic polymer matrix, capable of covalent attachment, as well as characterizing plates of the inorganic electrolyte lithium aluminum silicon phosporus titanium oxide (LASPT). This includes thermal and electrochemical characterization, including plate-strip measurements and impedance spectroscopy. To the end of better understanding these materials' electrochemical properties, the approach of systematically investigating various equivalent circuits is developed, for the purpose of modeling impedance data. A suitable silane polymer matrix, capable of covalent attachment, is found and dubbed "Entry 02". The chief lesson of this chapter is that function and performance need to be balanced, which in this case translates to covalent moieties and electrochemical performance, respectively. Chapter 4 centers around electrochemical characterization of model systems, consisting of a plate of the inorganic electrolyte LASPT sandwiched between two layers of an organic electrolyte. The organic electrolytes used are liquid and gel electrolytes, as well as the aforementioned Entry 02; the liquid electrolytes are combinations of different amounts of tetraglyme and lithium bis(trifluoromethanesulfonimide) (G 4 and LiTFSI), while the gel electrolytes are combinations of 1:1 G 4 :LiTFSI (termed a solvated ionic liquid, or SIL) and methylcellulose (MC), dubbed "SIL/MC films". The plate of inorganic electrolyte is either bare, or has had a controlled amount of silica (SiO 2 ) deposited onto its faces by way of atomic layer deposition (ALD). Subsequently, as will be seen in the following chapter, this layer is intended to be deposited on the surface of powdered inorganic electrolyte, for the purpose of facilitating covalent attachment of Entry 02. Achievement of this goal requires sufficient understanding of resistance at the organic- inorganic interface, a question that is addressed in this chapter; indeed, a planar geometry configuration allows for a simpler approach to tackling this problem. A systematic study of impedance data by way of an equivalent circuit investigation is undertaken; the main finding of this chapter is that the SiO 2 layer is not detected as a separate impedance feature, instead affecting existing impedance features of the starting components. Additionally, the presence of SiO 2 on the surface of LASPT plates has a positive effect for cyclic voltammetry (CV) and plate-strip experiments, improving the profile of voltammograms in the former case, and lowering the voltage profile while also increasing experiment duration in the latter case. Chapter 5 is the completion of efforts to prepare and characterize polymer- ceramic hybrid electrolytes, by combining the powedered inorganic electrolyte lithium aluminum germanium phosphate (LAGP) with Entry 02. A systematic study impedance data by way of equivalent circuits reveals a distribution of equivalent circuits, which is believed to correspond to a distribution of conduction paths. Plate-strip experiments also indicate that the presence of SiO 2 deposited onto the surface of LAGP particles has a positive effect on both duration and voltage profile. Chapter 6 studies the thermal and electrochemical properties of the cocrystalline electrolyte (the term "cocrystal" will be used interchangeably with "cocrystalline electrolyte") composed of adiponitrile and lithium hexafluorophosphate, (ADN) 2 LiPF 6 . Thermal properties of other cocrystals are also studied for comparison, namely with adiponitrile lithium hexafluoroarsenate (ADN) 2 LiAsF 6 , and adiponitrile lithium hexafluoroantimonate (ADN) 2 LiSbF 6 . In all cases, the cocrystals are found to be formed by high temperature (180 °C) dissolution and crystallization, a reversible phenomenon observed for both cocrystals prepared beforehand, and for raw, stoichiometric mixtures of the cocrystals’ components. Electrochemical characterization of hybrids of LAGP powder and (ADN) 2 LiPF 6 , as well as of (ADN) 2 LiPF 6 , is also performed. For hybrids, it is found from plate-strip experiments that performance is worse than for samples using only (ADN) 2 LiPF 6 , while impedance data shows that overall conductivity drops as the thickness of SiO 2 deposited onto LAGP particles increases. Thermal characterization data reveals that it is possible to quantify the amount of excess ADN present in (ADN) 2 LiPF 6 samples; impedance data indicates that excess ADN improves conductivity of these samples. Conductivity is hypothesized to depend heavily on the presence of a liquid layer, which is present in greater quantities when excess ADN is used – a feature that is believed to be present to a lesser extent when stoichiometric amounts of ADN and LiPF 6 are used. Full cell testing of (ADN) 2 LiPF 6 and saturated solutions of LiPF 6 in ADN reveals that conditioning the cells beforehand is beneficial to long-term cycling, but harmful to short-term discharge rate (C-rate) tests. It is hypothesized that conditioning allows for the formation of an interphase that is conducive to lower current, long-term testing; this interphase however is believed to be resistive in nature, explaining the inferior performance in C-rate tests, when compared to C-rate tests where the conditioning step is omitted. Chapter 7 concludes this work, by providing an overview and an outlook on the results and lessons learned in this work, with the chief lesson being that covalent attachment of an organic component to an inorganic one is a feasible strategy for preparing hybrid electrolytes. / Chemistry

Le but de cette thèse était de développer de nouveaux électrolytes polymères pour une application batteries lithium métal polymère. Le premier volet concerne le développement des réseaux semi-interpénétrés à base de POE et d'un polycondensat. Ces types d'électrolytes ont permis de d'améliorer les propriétés mécaniques et les conductivités à haute et basse température. L'ajout de NCC comme renfort sur ces réseaux semi-interpénétrés a permis d'atteindre propriétés physico-chimiques intéressantes et des durées de vie élevées. De plus l'hydrogénation du polycondensat permettant de moduler sont taux de réticulation a permis d'obtenir un électrolyte (en présence du LiTFSI) présentant des conductivités de 1S.cm-1 à 90°C pour un rapport O/Li=20 et O/Li=30 avec une tenue mécanique de 0,5MPa jusqu'à 100°C. Dans le second volet une série de sels de lithium à anion organique a été synthétisée et caractérisée. Ces sels de lithium présentent des bonnes stabilités électrochimiques, thermiques et des conductivités cationiques parfois plus élevées que LITFSI en milieu polymère. Le dernier volet concerne la synthèse et la caractérisation physico-chimique des nouveaux ionomères perfluoré. Ces nouveaux ionomères à conduction cationique unipolaire sont obtenus à partir de monomères aromatiques porteurs de fonctions ioniques ayant une forte aptitude à la dissociation et des nombres de transport cationique proche de 1 à 70°C. / The aim of this thesis was to develop new polymer electrolytes for application of lithium metal polymer batteries. The first part concerns the development of semi-interpenetrating networks based on POE and a polycondensat. These types of electrolytes made it possible to improve the mechanical properties and conductivity at high and low temperatures. The addition of NCC as a reinforcement on the semi-interpenetrating network has led to interesting physicochemical properties and high cycle life for batteries.The partial hydrogenation of the polycondensat allowing the modulation of the reticulation ratio has allow to elaborate as an electrolyte (in the presence of LiTFSI) exhibiting 1S.cm-1 conductivities at 90 ° C for a ratio O/Li=20 and O/Li=30 with a mechanical strength of 0.5MPa to 100 ° C. In the second part a range of lithium with organic anion was synthesized and characterized. These lithium salts show good electrochemical and thermal stability, whereas ionics conductivities are sometimes higher than LiTFSI in polymer medium. The last part concerns the synthesis and physicochemical characterization of new perfluorinated ionomers. These new cationic ionomers with a unipolar conduction are obtained from aromatic monomers carriers ionic functional having a high ability to dissociation and cation transport numbers close to 1 at 70 ° C.

Blends containing methoxyoligooxyethyleneglycol (MPEGs) (MW 350 and 550) and bis(trifluoromethane)sulfonimide lithium (LiTFSI) salt were prepared by solution blending process using tetrahydrofuran (THF) as a solvent. The ionic conductivity of the blends of different compositions were determined at four temperatures i.e. 25°C, 40°C, 60°C and 70°C. A maximum ionic conductivity value of 3.9x10-3 S cm-1 at 25°C was obtained for the blends containing MPEG-350 at an ethylene oxide to lithium salt ratio of 1:10. The ionic conductivity increases with increasing temperature and shows that the ion transport is aided by the segmental motion of the MPEG chains. 7Li NMR spectroscopy was used to study the nature and dynamics of the salt clusters in the blends