Analyzing the Stability and Kinetics of Ceramic Electrolyte/Organic Electrolyte Interfaces for LI Metal Batteries

The need for high-energy-density Li-ion batteries has provided the impetus to replace graphite anodes with Li metal anodes. Unfortunately, the liquid electrolytes (LEs) used in state-of-the-art (SOA) Li-ion batteries are unstable with Li metal. Owing to its high ionic conductivity, stability against Li and safety, Lithium Lanthanum Zirconium Tantalum Oxide (LLZTO), a solid ceramic electrolyte (SE), has been suggested as a promising alternative. However, the implementation of the SE in an all-solid-state battery could lead to cycling instabilities due to the formation of a resistive, electrochemically, and mechanically unstable cathode/SE interface. One potential approach to overcome the challenges is by introducing a gel polymer electrolyte (GPE) as a catholyte. In this hybrid electrolyte scheme, the LLZTO protects Li metal and a GPE improves the LLZTO/cathode interfacial stability and kinetics. The success of this approach, however, is reliant on two main assumptions – a) electrochemical properties of the GPE would not be affected by volumetric changes in the cathode during operation and b) the polymer and liquid electrolyte in the GPE will be (electro)chemically stable against LLZTO. The overarching goal of this thesis was to identify potential shortcomings of these assumptions and provide solutions to address them. To achieve this goal, the thesis was subdivided into three studies - 1) studying the effects of temperature and pressure on electrochemical performance of a model polymer electrolyte 2) understanding the factors controlling the polymer/LLZTO interfacial kinetics 3) evaluating the stability of LLZTO with potential LEs used in the GPE. With the aid of various characterization techniques including SEM, XRD, Raman Spectroscopy, XPS, electrochemical impedance spectroscopy, and galvanostatic cycling and unique experimental designs, several important implications were derived from each study. First, the roles of temperature and pressure on the electrochemical properties of the PEO-LiTFSI model system were evaluated. The results indicate that both, the bulk ionic conductivity and electrode/electrolyte charge transfer kinetics, are affected by temperature and stack pressure. It was observed that activation energy for Li-ion conduction shows a sharper transition at the melting point of the polymer for bulk conduction than for the electrode/electrolyte interface. It was also observed that a critical stack pressure was required to form an optimized electrode/electrolyte interface. Second, the factors controlling the kinetics and stability of LLZTO with both constituents of the GPE were analyzed. First, using PEO-LiTFSI the underlying factors that control the LLZTO/polymer interfacial kinetics were studied. It was found that the LLZTO surface impurities and Li-ion concentration gradient between the two electrolytes were responsible for the high interfacial resistance (Rinterface). The fundamental knowledge gained in this study enabled a reduction in the Rinterface from ~95 kOhms.cm2 down to 180 Ohms.cm2. Lastly, the stability of LLZTO was evaluated with different organic solvents and Li salts present in LEs. It was found that LiPF6-containing LE reacts with LLZTO to form LiF, LaF3, and ZrF4 at the interface leading to an increased SE/LE Rinterface. It was concluded that the chemical instability at LLZTO/LE interface was specific to the Li salt used. Thus, by selecting Li salts that exhibit stable behavior with LLZTO, the potential chemical instabilities can be avoided. Further, the optimization of Li salt concentration resulted in a low Rinterface (~30 Ohms.cm2). The culmination of the knowledge gained from the studies can be used for the development of hybrid electrolytes for enabling Li metal anodes.PHDMacromolecular Science & EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/163066/1/arushig_1.pd

Central Assistance to North Eastern States: A Comparative Analysis

The purpose of this study, titled ― Central Assistance to North Eastern States: A Comparative Analysis, is to assess the impact of change in recommendations of the Fourteenth Finance Commission and Union Budget 2015-16 on the North Eastern States of India. The study mainly focuses on the revised pattern of Central Assistance that is allotted to the NE States for the period 2015-16 (first year of the FFC term) as compared to 2014-15 (final year of the TFC term). In this project, the components of Central Assistance that we seek to look into are Block Grants, Grants-in-Aid and (prospective) data on Centrally Sponsored Schemes (CSS). Through this analysis, we have made an attempt to address the various claims regarding the adverse impact of the changed pattern of financial assistance

Central Assistance to North Eastern States: A Comparative Analysis

The purpose of our study, titled ― Central Assistance to North Eastern States: A Comparative Analysis, is to assess the impact of change in recommendations of the Fourteenth Finance Commission and Union Budget 2015-16 on the North Eastern States of India. The study mainly focuses on the revised pattern of Central Assistance that is allotted to the NE States for the period 2015-16 (first year of the FFC term) as compared to 2014-15 (final year of the TFC term). In this project, the components of Central Assistance that we seek to look into are Block Grants, Grants-in-Aid and (prospective) data on Centrally Sponsored Schemes (CSS). Through this analysis, we have made an attempt to address the various claims regarding the adverse impact of the changed pattern of financial assistance

New Definitions and Evaluations for Saliency Methods: Staying Intrinsic, Complete and Sound

Saliency methods compute heat maps that highlight portions of an input that were most {\em important} for the label assigned to it by a deep net. Evaluations of saliency methods convert this heat map into a new {\em masked input} by retaining the $k$ highest-ranked pixels of the original input and replacing the rest with \textquotedblleft uninformative\textquotedblright\ pixels, and checking if the net's output is mostly unchanged. This is usually seen as an {\em explanation} of the output, but the current paper highlights reasons why this inference of causality may be suspect. Inspired by logic concepts of {\em completeness \& soundness}, it observes that the above type of evaluation focuses on completeness of the explanation, but ignores soundness. New evaluation metrics are introduced to capture both notions, while staying in an {\em intrinsic} framework -- i.e., using the dataset and the net, but no separately trained nets, human evaluations, etc. A simple saliency method is described that matches or outperforms prior methods in the evaluations. Experiments also suggest new intrinsic justifications, based on soundness, for popular heuristic tricks such as TV regularization and upsampling.Comment: NeurIPS 2022 (Oral

Impact of levonorgestrel intrauterine system on metabolic parameters

Background: Hormonal contraceptive is suggested to affect parameters like body mass index, body weight, blood pressure (BP), blood sugar, lipid protein, and liver function test (LFT) but effect of LNG-IUS on those parameters is still uncertain. The aim of the present study was to study the effects of LNG-IUS on the metabolic parameters.Methods: Sixty women who opted for LNG-IUS for various indications were included in the study. Lipid profile, liver function tests (LFT), glucose levels [fasting and post prandial (PP)], and hemoglobin (Hb) were tested. Bimanual genital examination and transvaginal-ultrasonography was done prior to LNG-IUS insertion. Any problems observed were recorded. The subjects were re-evaluated after 6 and 9 months on their subsequent visits. Data were analyzed using paired “t” test. P value of <0.05 was considered statistically significant.Results: Mean age of the patients was 35.5±6.79 years. Maximum number 50 (83.3%) had abnormal uterine bleeding (ovulatory dysfunction, endometrial, iatrogenic, not yet classified) [AUB (OEIN)]. Mean pictorial blood loss assessment chart (PBAC) score of patients was 164.7±56.72 and mean Hb level 11.15±1.75g/dL. LNG-IUS showed no significant adverse effects on anthropometric parameters at 6- and 9-month follow-up. Significant change was seen in total cholesterol (TC), very low-density lipoprotein (VLDL) and high density lipoproteins (HDL) values at follow-up (p<0.0001).Conclusions: In conclusion, amongst Asian population, the LNG-IUS does not have any adverse effects on metabolic parameters, TGs, LDL and blood sugar levels