Thermodynamics of Ionic Bonding with Crown Ethers in Aqueous Solution

The usage of lithium-ion batteries has skyrocketed due to the advent of consumer electronics and electric vehicles. Concerns about lithium supply and battery waste have prompted interest in lithium recycling methods. The crown ether, 12-crown-4, has been studied for its abilities to form stable complexes with lithium. In this thesis, molecular dynamics simulations are applied to examine the binding properties of a 12-crown-4—lithium system in aqueous solution. In addition, the binding properties of sodium to 12-crown-4 are examined for comparison. It was found that 12-crown-4 did not form stable complexes with lithium in aqueous solution due to the binding geometry which was prone to interference by surrounding water molecules. Subsequently, calculations were performed with the crown ethers 15-crown-5 and 18-crown-6 to study their complexation with lithium as well. It was determined that binding was unfavorable for all three crown ethers tested, though 15-crown-5 and 18-crown-6 showed a marginally greater affinity for lithium than 12-crown-4.