Multiscale Computational Study on Materials Design for Advanced Applications in Secondary Batteries and Environmental Sustainability

Abstract

Non-renewable fossil fuels remain as the primary energy sources to fulfill global energy demand. This presents a double-edged sword, as the extensive use of fossil fuels has a significant environmental impact. To mitigate the environmental impact of fossil fuel consumption, significant advancements have been made in renewable energy engineering and the utilization of greenhouse gases produced from fossil fuels combustion. However, this progress introduces additional challenges related to energy storage, making the continued advancement of energy storage technologies (e.g., batteries) equally critical for enabling a sustainable renewable energy approach. In parallel, the utilization of greenhouse gases has driven the development of novel adsorbent materials for effective gas adsorption and separation, which has become an active research field. In the development of advanced batteries and adsorbent materials, theoretical analysis from an atomic and molecular perspective provides invaluable insight into the atomic level that are often challenging to be interpreted from experimental methods alone. Therefore, it is essential to conduct theoretical study using multiscale simulations. The introduction of computational chemistry enables the interpretation of atomic-scale phenomena, including the interfacial properties, conduction and coordination behavior within systems, and electronic structure characteristics, enabling the prediction of physicochemical properties. In this dissertation, we focus on structural factors for designing of organic electrode for lithium metal batteries, inorganic/organic composite electrolytes, polymer electrolytes for all-solid-state batteries, and adsorbent materials with selective carbon monoxide (CO) adsorption properties. These topics will be discussed in the context of molecular modelling and multiscale simulation, providing comprehensive understanding for performance improvements observed. This dissertation focuses on the design of battery materials and gas adsorbent materials, along with extensive analysis on the underlying factors that contribute to their enhanced performance. Materials properties were investigated from an atomic and molecular perspective using thermodynamic parameters. Among the multiscale simulation methods, density functional theory (DFT), Monte Carlo (MC), and molecular dynamics (MD) simulation were optimized and employed to analyze and predict relevant phenomena. In Chapter 2, an electroactive organic anode material is engineered to achieve high energy density lithium metal batteries by allowing conformal lithium deposition. Thermodynamic parameters are utilized to characterize the observed phenomena. The electroactive organic material, Li2C8H4O4 (Li2TP), functions as both a lithium host and a guided deposition medium. The surface stability of the lithiated Li2TP (Li4TP) structure and its interaction characteristics with lithium atoms were analyzed to assess the possibility of stable lithium deposition. Furthermore, the lithium layer type formation energy on Li4TP was found to be negative compared to that on a Cu substrate, indicating favorable conditions for conformal deposition. This exhaustive investigation highlights the potential of the electroactive organic anode material as bifunctional medium for both lithium hosting and conformal deposition. In Chapter 3, the structural factors contributing to the enhanced ion conduction in inorganic/organic composite and polymer electrolytes, along with the underlying mechanisms responsible for the observed improvement in performance, were elucidated. The ion conduction at the percolated inorganic phase and inorganic/organic interface derived from the LPSCl/GPE composite electrolyte was analyzed using MD simulations. In order to enhance the ion conduction, the solvation properties were regulated by controlling the elasticity and chain length of the glyme. Notably, lithium ion desolvation property, which becomes more favorable with shorter short glyme chain length, was observed to enhance ionic mobility at the interface. For polymer electrolyte design, the focus was placed on ion conduction by addressing lithium salt dissociation and its interaction characteristics with the precursor. Theoretical analysis proposed a zwitterionic monomer containing TFSI− anionic moiety, which has weak interactions with lithium, and a LiBETI salt with high dissociation properties. The theoretical analysis revealed that the introduction of the monomer form resulted in uniform mixing and aligned channel formation, which led to enhanced ion mobility. This evidence indicated that the zwitterionic monomer-based electrolyte promotes homogeneous mixing and aligned channel formation, resulting in enhanced ion conduction. In Chapter 4, the results of DFT calculations and electronic structure analysis on the design of activated carbon-based adsorbents for the selective adsorption of low concentrations of CO from industrial by-product gases were presented. In order to enhance the adsorption properties of CO relative to carbon dioxide (CO2), we explored the incorporation of functional groups on the surface of activated carbon and the impregnation of metal halide clusters, specifically (CuCl)n (n = 1-3). For functional groups, oxygen and nitrogen containing structures, commonly found in activated carbon, were identified as the most suitable candidates. It was established that the smallest dispersed (CuCl)1 and nitrogen-based −NH2 functional group exhibited the highest CO selectivity among the modified systems. Orbital and electronic structure analyses of the bonding properties associated with the CO adsorption strength revealed an increase in electron transfer facilitated by 5σ and 2π* interactions. These findings provided an inclusive theoretical analysis for the enhanced CO adsorption performance of −NH2 functional groups compared to other element-based functional groups.