Introduction
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UT Tower and campus image credit: Earl McGehee, CC-BY, https://www.flickr.com/photos/ejmc/7452145850
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Delineating the interfacial interactions and gas evolution in low-cobalt, high-energy density lithium-based batteries
(December 2023) Sim, Richard, Ph. D.; Manthiram , Arumugam; Yu, Guihua; Hwang, Gyeong; Subramanian, Venkat
Layered oxides (LiNi₁₋ [subscript x] M [subscript x] O₂; M = Co, Mn, Al) are promising cathode materials that can achieve key performance metrics with their high energy densities and rate performance. However, these materials suffer from a series of surface and bulk degradations during charge-discharge that may compromise the performance and safety of the battery. This dissertation focuses on elucidating the surface and bulk degradation mechanisms that result from electrode-electrolyte incompatibility for high-energy layered-oxide cathodes and lithium-metal anodes. Extensive discussions are provided on the set-up of specialized instrumentation for advanced gas detection and application of advanced characterization tools to elucidate the surface interfacial reactions at the electrode-electrolyte interface for the development of sustainable, safe, and long-lasting lithium-based batteries. An evaluation of the influence of calendering on cobalt-free LiNi₀.₉Mn₀.₀₅Al₀.₀₅O₂ (NMA-90) cathodes is explored as a facile method to minimize the degree of electrode-level effects on cell performance for future projects. Calendered NMA-90 | graphite full cells exhibit lower cell impedance, enhanced cyclability, and pulse-power performance. Overall, calendering is demonstrated to be a crucial post-processing technique for commercial high-nickel cathodes. Gas evolution from the cathode at high voltages remains a pervasive issue for practical batteries. The details of the design and set-up of an online electrochemical mass spectrometry system (OEMS) that operates well for cells with lean and volatile electrolytes is provided. This system is applied to a broad series of cathode-electrolyte systems and charging conditions to elucidate the factors leading to gas release from the cathode. Important topics to gas evolution from the layered-oxide cathode, including voltage, state of charge, cathode composition, electrolytes, and surface coatings are discussed. A separate pathway to achieving high energy densities with the cathode is to increase the upper cut-off voltage of the battery to 4.6 V from the standard 4.4 V vs Li/Li⁺. A localized saturated electrolyte (LSE) is employed to enable the stable cycling of a cobalt-free, low-nickel LiNi₀.₇Mn₀.₂₅Al₀.₀₅O₂ in lithium-metal half-cells. It is found that the improvements to the cycling performance are due to a beneficial interphase layer, reduced degree of rock-salt phase formation, and reduced gas evolution from the cathode. Transition-metal dissolution from the cathode is exacerbated at high voltages, which will influence solid-electrolyte interphase (SEI) formation at the anode. Secondary-ion mass spectrometry (SIMS) is employed to track the distributions of common products found in the SEI. Spatial correlations between deposited transition-metals, organic/inorganic electrolyte decomposition products, and lithium metal on the lithium-metal anode are established and quantified for a variety of anodes cycled with different cobalt-free cathodes and electrolytes. Critical insights into the effects of spatial heterogeneity and SEI localization on cell cyclability are provided.
They Always Get Our Story Wrong”: Addressing Social Justice Activists’ News Distrust Through Solidarity Reporting
(Media and Communication, 2023-12) Varma, Anita; Limov, Brad; Cabas‐Mijares, Ayleen
This study positions social justice activists’ objections to dominant reporting norms as a catalyst for critically reassessing
these norms and their connection to diminishing trust in US journalism. Based on a conceptual application of discourse
ethics to journalism and qualitative analysis of 28 in‐depth interviews with social justice activists, we examine how par‐
ticipants experience and evaluate mainstream coverage of social justice, and why they think journalism could improve its
trustworthiness through practices consistent with solidarity reporting norms.
Marine Science Library Annual Report September 1, 1995 - August 31, 1996
(1996) Grundy, Ruth
Marine Science Library Annual Report September 1, 1993 - August 31, 1994
(1994) Grundy, Ruth
Marine Science Library Annual Report September 1, 1991 - August 31, 1992
(1992) Grundy, Ruth