Computer simulations of co2 absorption in amino acid ionics and ion conduction in alkali metal battery electrolytes

Abstract

This thesis presents modeling and simulations on absorbents for carbon dioxide capture and electrolytes for Li Na ion batteries In the first part of the thesis Lysine amino acid based Ionic Liquids IL and Salts AAS are explored as potential replacements for conventional absorbents for carbon capture like amines amine alcohol blends etc Classical molecular dynamics MD simulations are performed to examine the molecular mechanism of CO2 absorption in tetrabutylphosphonium Lys IL The simulations suggest that an interface of CO2 molecules form at the IL surface within a short span of tens of picoseconds and attains saturation around ten nanoseconds where CO2 molecules remain absorbed in the bulk IL layers The interaction and absorption of CO2 molecules leads a slightly higher mobility of anions than cations due to the preferential interaction of CO2 molecules Density Functional Theory DFT calculations are also employed to understand the mechanism for Lys CO2 reaction and participation of a single molecule of water in this reaction The calculations show the existence of various non bonded complexes and chemical reactions responsible for CO2 absorption and desorption The reaction mechanisms in each complex are characterized by energy parameters such as binding energy activation energy and reaction energy The competitive reaction pathways which show the dominance of carbamate over bicarbonate products during CO2 absorption are also discussed The simulations and calculations serve as a predictive tool to develop efficient AAILs for CO2 absorption In the second part of the thesis the thermal stability and mechanism of ion conduction in a new generation of soft solid cocrystalline electrolytes for Lithium and Sodium Ion Batteries are investigated Four cocrystalline solid electrolytes composed of alkali metal salts and organic solvents adiponitrile ADN and N N dimethylformamide DMF solvents in stoichiometric ratios DMF 8729 LiCl DMF 3NaClO4 ADN 3NaClO4 and ADN 2LiPF6 are examined for their struct newline newline