Unveiling the Electrochemical Characteristics of Na-CO2 battery Catholytes through NASICON-Based Hybrid cells

School of Energy and Chemical Engineering (Energy Engineering (Battery Science and Technology))The high levels of greenhouse gases in the atmosphere are leading to climate change. To address this problem, the concept of "net zero" has been introduced. Achieving net zero means balancing the amount of greenhouse gas emissions produced with the amount removed from the atmosphere. To achieve net zero, it is essential to focus on reducing emissions to the greatest extent feasible. This can be accomplished through various measures such as adopting cleaner technologies, improving energy efficiency, and promoting sustainable practices across different sectors. Net zero is an important goal in the fight against climate change as it aims to limit global temperature increases and negative impacts on the environment and human well-being. Alkali metal-CO2 batteries have the potential to help address the energy problem and climate change by combining CO2 utilization with energy storage. Among them, Na-CO2 batteries are particularly promising for achieving net-zero because they can address both the energy and environmental crises. The use of Na-CO2 batteries can help capture and store CO2, which is a greenhouse gas that contributes to climate change. Furthermore, Na-CO2 batteries offer a high theoretical energy density and are cost-effective compared to other energy storage technologies. Nevertheless, while Li-CO2 batteries have been extensively researched, Na-CO2 batteries are still in the early stages of exploration. Challenges such as short-term cycle life, low reversibility, and high overpotentials have hindered their commercial viability. To address these limitations and advance the development of Na-CO2 batteries, it is crucial to gain a comprehensive understanding of the underlying electrochemistry that govern their working, as well as establish the relationship between cell configurations and functionality. To enhance the development of Na-CO2 batteries, The new-type of electrolytes have been investigated to enhance their electrochemical characteristics. One type of solid-state electrolyte, NASICON, was effective in protecting the Na metal anode and preventing dendrite growth that can cause a short circuit. In addition, the use of different electrolyte systems, such as the water-in-salt (WiS) electrolyte and acetonitrile (MeCN) electrolyte with NASICON, was explored in Chapters 2 and 3, respectively. In the Chapter 2, the WiS (water-in-salt) electrolyte concept was introduced. This innovative electrolyte consists of saturated concentration of salt that enables the solubility of water within it. The WiS electrolyte system offers several advantages, including improved stability, a wider electrochemical stability window, and higher conductivity compared to traditional electrolytes. To enhance the electrochemical properties of Na-CO2 batteries, nano-sized ruthenium was utilized as a cathodic catalyst. The incorporation of Ru@carbon current collectors in Na-CO2 batteries led to reduction in the overpotential gap, which refers to the excess voltage needed to initiate a desired electrochemical reaction. Additionally, the batteries demonstrated a cycling endurance of over 75 cycles, equivalent to 50 days, with minimal degradation. These findings indicate that the implementation of WiS-based Na-CO2 batteries, which utilize CO2 as a reactant, could be a cost-effective solution for energy storage applications. The combination of the WiS electrolyte and ruthenium catalyst contributes to improved battery performance, making it a promising option for efficient and sustainable energy storage. Chapter 3 focused on investigating acetonitrile (MeCN) as a catholyte in conjunction with NASICON electrolyte for Na-CO2 batteries. While acetonitrile exhibits favorable characteristics such as a high dielectric constant and low viscosity, it reacts with Na metal and cannot be directly used in Na-CO2 batteries. To overcome this challenge, a NASICON-based hybrid cell configuration was developed to enable the utilization of MeCN-based electrolyte. Additionally, the previously reported glyme-based electrolyte was employed in the same system to assess the impact of different electrolytes on Na-CO2 batteries. Electrochemical properties of both electrolytes were thoroughly examined, and computational simulations, including Density Functional Theory (DFT) and Molecular Dynamics (MD), were conducted to provide insights into the effects of electrolytes on Na-CO2 batteries. The simulation results indicated that the diffusion barrier, which represents the resistance to ion movement, was lower for the MeCN-based catholyte compared to the electrolyte employing tetraethylene glycol dimethyl ether (TEGDME). This lower barrier facilitated faster movement of sodium ions due to the solvation structure of Na+ ions in MeCN. As a result, the Na-CO2 battery operated successfully, demonstrating the higher efficiency of the MeCN-based electrolyte in terms of ion movement compared to the TEGDME-based electrolyte.clos

Optimizing PET Glycolysis with an Oyster Shell-Derived Catalyst Using Response Surface Methodology

Polyethylene terephthalate (PET) waste was depolymerized into bis(2-hydroxyethyl) terephthalate (BHET) through glycolysis with the aid of oyster shell-derived catalysts. The equilibrium yield of BHET was as high as 68.6% under the reaction conditions of mass ratios (EG to PET = 5, catalyst to PET = 0.01) at 195 °C for 1 h. Although biomass-derived Ca-based catalysts were used for PET glycolysis to obtain BHET monomers, no statistical analysis was performed to optimize the reaction conditions. Thus, in this study, we applied response surface methodology (RSM) based on three-factor Box–Behnken design (BBD) to investigate the optimal conditions for glycolysis by analyzing the independent and interactive effects of the factors, respectively. Three independent factors of interest include reaction time, temperature, and mass ratio of catalyst to PET under a fixed amount of ethylene glycol (mass ratio of EG to PET = 5) due to the saturation of the yield above the mass ratio. The quadratic regression equation was calculated for predicting the yield of BHET, which was in good agreement with the experimental data (R2 = 0.989). The contour and response surface plots showed the interaction effect between three variables and the BHET yield with the maximum average yield of monomer (64.98%) under reaction conditions of 1 wt% of mass ratio (catalyst to PET), 195 °C, and 45 min. Both the experimental results and the analyses of the response surfaces revealed that the interaction effects of reaction temperature vs. time and temperature vs. mass ratio of the catalyst to the PET were more prominent in comparison to reaction time vs. mass ratio of the catalyst to the PET

???Water-in-salt ???and NASICON Electrolyte-Based Na???CO 2 Battery

Super concentrated electrolytes, referred to as "water-in-salt (WiS) electrolytes", are being increasingly employed because of their wide electrochemical stability window, cost-effectiveness, and non-flammability. However, the free water molecules present in WiS electrolytes prevent the use of highly abundant, low-cost Na metal as the anode for various Na-gas batteries. In this study, we develop a WiS-based hybrid Na-CO2 battery that utilizes CO2 and serves as an energy storage cell, where a Na super-ionic conductor enables us to directly use Na metal as the anode component and a WiS electrolyte for the cathode electrolyte. In particular, linear sweep voltammetry with corresponding differential electrochemical mass spectrometry ensures an expanded electrochemical stability window, which guarantees Na-CO2 operation without electrolyte degradation during the charge process. Furthermore, we introduce a nano-sized Ru catalyst to the current collector using the Joule-heating method for lowering the discharge-charge gap. Consequently, the Na-CO2 batteries with these Ru@carbon current collectors reduce the overpotential gap and exhibit a cycling endurance of over 75 cycles (50 days) without significant alteration. These promising results demonstrate the potential of cost-effective, WiS-based Na-CO2 batteries that utilize CO2 and can be employed as energy storage cells

Bimodally-porous alumina with tunable mesopore and macropore for efficient organic adsorbents

Since it is of great importance to remove aqueous pollutants for distributing clean water, the adsorption of toxic chemicals on solid adsorbent has been the most practical technique. As one of the widely-accepted design for an adsorbent, hierarchical channel or structurally-connected large and small pore networks take several advantages for application in catalysis and adsorption in liquid or gaseous environment. Mesoporous networks can provide size and shape selectivity for foreign molecule, while macropores can reduce transport limitations and increase the accessibility to the active sites. In this study, we adopted alumina as an adsorbent of organic pollutants due to its easy structural engineering in crystal structure, textural properties, and morphology. As an efficient organic adsorbent, bimodally-porous alumina (BPA) was synthesized to contain mesopores and macropores, which were able to be structured in a separately-controllable manner via solvent-deficient hydrolysis method. The macropores are formed by using polymer beads as a sacrificial template. Additionally, the mesoporous framework is structured through controlling hydrolysis reaction between aluminum alkoxides and water. After calcination, the BPA was pelletized into cylinder or coin shapes for recycling adsorbents without separation and collection steps. We examined the systematic characteristics of the BPA samples, which are associated with the optimal adsorption capability in terms of surface conditions and structural/morphological difference

A recyclable catalyst made of two-dimensional gold-loaded cellulose paper for reduction of 4-nitrophenol

Two-dimensional gold nanostructures with controlled edge length and thickness were synthesized into polygonal shapes categorized as smooth/jagged-edged and single/multiple-layered nanosheets. Despite their micrometer-scaled lateral dimension, the high catalytic activity of the 2D Au nanostructures was observed in the reduction reaction of 4-nitrophenol to 4-aminophenol in the presence of NaBH4. We studied the dependability of the catalytic performance on the edge area by examining the relationship between rate constants and catalytically active area of single-layered, jagged-edged, and multiply stacked 2D Au nanostructures. Furthermore, we successfully fabricated a robust and reusable catalyst by incorporating 2D Au nanostructures in a cellulose paper as a flexible substrate through the monolayer assembly and transfer method. The comparative study shows that multiply stacked Au nanosheets on a paper substrate outperformed the other Au nanostructures including nanoparticle. (C) 2020 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved

Sacrificial Catalyst of Carbothermal-Shock-Synthesized 1T-MoS2 Layers for Ultralong-Lifespan Seawater Battery

A Pt-nanoparticle-decorated 1T-MoS2 layer is designed as a sacrificial electrocatalyst by carbothermal shock (CTS) treatment to improve the energy efficiency and lifespan of seawater batteries. The phase transition of MoS2 crystals from 2H to metallic 1T???induced by the simple but potent CTS treatment???improves the oxygen-reduction-reaction (ORR) activity in seawater catholyte. In particular, the MoS2-based sacrificial catalyst effectively decreases the overpotential during charging via edge oxidation of MoS2, enhancing the cycling stability of the seawater battery. Furthermore, Pt nanoparticles are deposited onto CTS-MoS2 via an additional CTS treatment. The resulting specimen exhibits a significantly low charge/discharge potential gap of ??0.39 V, high power density of 6.56 mW cm???2, and remarkable cycling stability up to ???200 cycles (???800 h). Thus, the novel strategy reported herein for the preparation of Pt-decorated 1T-MoS2 by CTS treatment could facilitate the development of efficient bifunctional electrocatalysts for fabricating seawater batteries with long service life

Gradient Lithium Metal Infusion in Ag-Decorated Carbon Fibers for High-Capacity Lithium Metal Battery Anodes

Lithium (Li) metal is a promising anode material for high-energy-density Li batteries due to its high specific capacity. However, the uneven deposition of Li metal causes significant volume expansion and safety concerns. Here, we investigate the impact of a gradient-infused Li-metal anode using silver (Ag)-decorated carbonized cellulose fibers (Ag@CC) as a three-dimensional (3D) current collector. The loading level of the gradient-infused Li-metal anode is controlled by the thermal infusion time of molten Li. In particular, a 5 s infusion time in the Ag@CC current collector creates an appropriate space with a lithiophilic surface, resulting in improved cycling stability and a reduced volume expansion rate. Moreover, integrating a 5 s Ag@CC anode with a high-capacity cathode demonstrates superior electrochemical performance with minimal volume expansion. This suggests that a gradient-infused Li-metal anode using Ag@CC as a 3D current collector represents a novel design strategy for Li-metal-based high-capacity Li-ion batteries

Unveiling the electrochemical characteristics of acetonitrile-catholyte-based Na-CO2 battery

The development of metal-CO2 batteries has attracted intense attention because of their unique electrochemical reaction for utilization of CO2 gas. However, unlike the alkali metal-based O2 batteries, a limited number of combinations of aprotic electrolytes have been employed for Li(Na)???CO2 batteries due to the sluggish reaction for the formation of the Li(Na)2CO3 discharge product. Here, we demonstrate an acetonitrile (MeCN)-based catholyte for use in a hybrid cell type Na-CO2 battery. The presence of a solid ceramic separator in our hybrid cell allows the stable operation of the MeCN catholyte-based Na-CO2 battery, resulting in improved electrochemical characteristics such as low overpotential, high energy density, and long cycle stability compared to the conventional TEGDME-based electrolyte. In particular, results of molecular dynamics simulations suggest that the improved performance is mainly due to the enhanced Na+ diffusion in the electrolyte. The calculated barrier for Na+ diffusion in MeCN is approximately four times lower than that in TEGDME. Thus, this work provides a promising electrolyte combination and reveals the mechanism for the improved performance of the MeCN-based electrolyte used in the hybrid cell structure, promoting the development of Na-CO2 batteries as practical secondary energy storage devic

Carbothermal shock-induced bifunctional Pt-Co alloy electrocatalysts for high-performance seawater batteries

Seawater batteries consisting of Na anode, Na super-ionic conductor separators, and seawater catholytes have received wide attention because of their theoretical specific capacity of 1160 mAh g???1 and cost-effective Na anode in comparison to rare-earth Li. However, large overpotential during charge and discharge caused by parasitic reactions limits their practical applications. In this work, we employ the bifunctional Pt-Co alloy electrocatalysts produced by carbothermal shock (CTS) method to improve the oxygen evolution and reduction reaction activities of seawater batteries. The CTS induced Pt-Co alloy nanoparticles are well synthesized and dispersed on a carbon current collector within a few s, resulting in improved overpotential and cycle endurance of seawater batteries compared to pristine carbon cathode. In particular, the cell can operate for over 500 h in a seawater catholyte at a fixed capacity of 0.25 mA cm???2 without significant performance degradation. Furthermore, CTS can be readily applied to large-area prismatic seawater battery cells. We observe excellent cyclability in a large-scale seawater battery, suggesting that bifunctional Pt-Co alloy electrocatalysts produced by CTS are viable for use in seawater batteries

The Prognostic Significance of the Overexpression of HER-2/ neu in Korean Gastric Carcinomas and the In Vitro Effects of Anti-HER-2/neu Antibody on Cell Growth in the Gastric Carcinoma Cell Lines

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