Date of Award
Doctor of Philosophy (PhD)
Stuart, Steven J
Stuart, Steven J
Molecular bombardment experiments have led to the possibility of altering materials with properties not normally associated with those materials. Molecular bombardment leads to defect formation in the material, potentially creating a pore, depending on the material and bombarding molecule. Carbon allotropes, specifically graphite and graphene, make excellent candidates for molecular bombardment experimentation. Depending on the bombarding molecule and the kinetic energy associated with that molecule, the defects induced will be sufficient to create a pore in the graphene. The AIREBO potential is used to simulate a graphene bilayer being bombarded with a single Ar atom, or a fullerene molecule, to induce the formation of a pore. The system is then annealed to simulate bond restructuring. Analysis of the pore formation is performed using a model that incorporates ring formation in the graphene bilayer as an indicator of completeness, along with the area of the pore. Graphite has become a popular medium for intercalating lithium atoms, making it useful as an anode in Li-ion batteries. However, graphite has a relatively low specific capacity, compared to pure lithium. In search of a higher specific capacity, a novel carbon material, graphyne, which is a theoretically proposed material that consist of two-dimensional networks of carbon with both sp and sp2 hybridized bonds, has been proposed as a superior adsorbent. Previous theoretical studies have shown that graphyne has the ability to intercalate more lithium atoms per carbon atom than all other known carbon allotropes. Experimental studies have found that introducing other metals such as calcium can increase the amount of Li intercalated into materials like graphite. DFT calculations implemented in VASP are used to calculate how the binding energy of lithium is affected by the intercalation of calcium into graphite and graphyne in an attempt to further increase lithium concentrations. Lithium intercalation is found to improve in both materials with the addition of the calcium cointercalant.
Lowe, Charles, "Bombardment Simulations and Intercalation Studies of Carbon Materials" (2015). All Dissertations. 1560.