MULTI-LAYERED, VARIABLE POROSITY SOLID- STATE LITHIUM-ION ELECTROLYTES: RELATIONSHIP BETWEEN MICROSTRUCTURE AND LITHIUM-ION BATTERY PERFORMANCE

The global drive to create safer, higher capacity energy storage devices is increasingly focused on the relationship between the microstructures of electrochemically- active materials and overall battery performance. The advent of solid-state electrolytes with multi-layered, variable porosity microstructures opens new avenues to creating the next generation of rechargeable batteries, while creating new challenges for device integration and operation. In this dissertation, microstructures of solid-state Li-ion conducting electrolytes were characterized to identify the primary limiting factors on electrolyte performance and identify structural changes to improve porous electrolyte performance in dense-porous bilayer systems. LLZO-based garnet electrolytes were fabricated with varied porosity and characterized using 3D Focused Ion Beam (FIB) Tomography, enabling digital reconstructions of the underlying 3D microstructures. Ion transport through the microstructures was analyzed using M-factors, which identified garnet volume fraction and bottlenecks as primary limiters on effective conductivity, followed by geometric tortuosity. Notably, a template-based porous microstructure displayed a low tortuosity plane and a high tortuosity direction, as opposed to the more homogenous tape-cast porous microstructures. To evaluate the performance of these microstructures in Li symmetric cells, dense-porous bilayers were digitally constructed using the FIB Tomography microstructures as porous layers with fully infiltrated Li-metal electrodes, and equilibrium electric potentials were simulated. The bilayers had area-specific resistance (ASR) values similar to the ASR value of the dense layer alone. The bilayer ASR also decreased as porous layer porosity increased, due to ion transport occurring primarily through the dense layer-electrode interface and higher porosity creating higher interfacial area. Artificial bilayers were created with porous layers composed of columns for a range of column diameters/particle sizes, porous layer porosities, and porous layer thicknesses. The bilayer ASR decreased with increasing porosity and decreasing column diameter, similar to the FIB Tomography bilayers. However, bilayer ASR dramatically increased when only partially infiltrated with electrodes, and instead increased with increasing porosity and decreasing column diameter. The simulation results showed that fabricating solid-state bilayer symmetric cells with low ASR required high porosity porous microstructures with small particle sizes, and electrodes completely infiltrated to the dense layer

Effect of the 3D Structure and Grain Boundaries on Lithium Transport in Garnet Solid Electrolytes

Lithium metal anodes are vital enablers for high-energy all-solid-state batteries (ASSBs). To promote ASSBs in practical applications, performance limitations such as the high lithium interface resistance and the grain boundary resistance in the solid electrolyte (SE) need to be understood and reduced by optimization of the cell design. In this work, we use our 3D microstructure-resolved simulation approach combined with a modified grain boundary transport model for the SE to shed some light on the aforementioned limitations in garnet ASSBs. Using high-resolution volume images of the SE electrode sample, we are able to reconstruct the SE microstructure. Using a grain segmentation algorithm, we further distinguish individual grains and account for the influence of the SE grain size and grain boundaries. We focus our simulation work on the trilayer cell architecture, consisting of two porous SE electrodes separated by a dense layer. Even though the highly porous SE electrodes reduce the lithium interface resistance by providing a higher active surface area, the increased electrode tortuosity also reduces the effective ionic conductivity in the SE. We confirm via impedance simulation studies and validation against experimental results that with increasing SE electrode porosity, the lithium transport becomes limited by grain boundaries. We also correlate the area-specific resistance to different lithium infiltration stages in the trilayer cell by spatially resolving the current density distribution. This analysis allows us to suggest a plausible deposition mechanism, and moreover, we identify current density hot spots in the proximity of the dense layer. These hot spots might lead to dendrite formation and long-term cell failure. The joint theoretical and experimental study gives guidelines for cell design and optimization which allow further improvement of the trilayer architecture

Oxide‐Based Solid‐State Batteries: A Perspective on Composite Cathode Architecture

The garnet-type phase Li$_7$La$_3$Zr$_2$O$_{12}$ (LLZO) attracts significant attention as an oxide solid electrolyte to enable safe and robust solid-state batteries (SSBs) with potentially high energy density. However, while significant progress has been made in demonstrating compatibility with Li metal, integrating LLZO into composite cathodes remains a challenge. The current perspective focuses on the critical issues that need to be addressed to achieve the ultimate goal of an all-solid-state LLZO-based battery that delivers safety, durability, and pack-level performance characteristics that are unobtainable with state-of-the-art Li-ion batteries. This perspective complements existing reviews of solid/solid interfaces with more emphasis on understanding numerous homo- and heteroionic interfaces in a pure oxide-based SSB and the various phenomena that accompany the evolution of the chemical, electrochemical, structural, morphological, and mechanical properties of those interfaces during processing and operation. Finally, the insights gained from a comprehensive literature survey of LLZO–cathode interfaces are used to guide efforts for the development of LLZO-based SSBs

Human matrix metalloproteinases: An ubiquitarian class of enzymes involved in several pathological processes

Human matrix metalloproteinases (MMPs) belong to the M10 family of the MA clan of endopeptidases. They are ubiquitarian enzymes, structurally characterized by an active site where a Zn(2+) atom, coordinated by three histidines, plays the catalytic role, assisted by a glutamic acid as a general base. Various MMPs display different domain composition, which is very important for macromolecular substrates recognition. Substrate specificity is very different among MMPs, being often associated to their cellular compartmentalization and/or cellular type where they are expressed. An extensive review of the different MMPs structural and functional features is integrated with their pathological role in several types of diseases, spanning from cancer to cardiovascular diseases and to neurodegeneration. It emerges a very complex and crucial role played by these enzymes in many physiological and pathological processes

Abundant : Australian pavilion 11th international architecture exhibition la biennale de Venezia 2008 /

CD-ROM: Abundant Australia, media kit and imagesPatterns, translations, narratives - Australian architecture: themes in a diverse culture / Conrad Haman