Atomistic Insights into Ti-MXenes and Derived Structures for Energy Storage

Abstract

The increased demands of energy consumption motivates the development of efficient and high-performance materials for implementation in energy-storage devices. MXenes are a family of two-dimensional transition metal carbides with superior performance in energy-storage owing to their extraordinary physical and chemical properties. Characterized by the excellent electrical conductivity, ion adsorption, and mechanical stiffness, Ti-MXenes are attractive candidates for Li-ion batteries anodes. However, the restacking of layers degrades their electrochemical performance. Ti-MXenes offer a one-step synthesis method for carbon-supported TiO2, which is an interesting material for Li-ion batteries electrodes and photocatalysis. Nevertheless, the absence of complete understanding for the thermal degradation and phase transformation of Ti-MXenes to carbon-supported Ti-O phases suggests that further research is required to aid the synthesis process. In this study, reactive molecular dynamics simulations are used to provide atomistic insights into the thermal decomposition of Ti-MXenes and first-principles calculations are used to propose a new heterostructure between Ti3C2O2 and Boron-Phosphide as a high-performance Li-ion battery anode. The analysis revealed that dry air provides an effective environment for the formation of carbon-supported TiO2, and that vacuum environment facilitates the formation of cubic TiO. The water environment was shown to inhibit the formation of distinct phases. On the other hand, Ti3C2O2/Boron-Phosphide heterostructure shows higher electrical conductivity than the individual monolayers with a theoretical capacity (757 mAh/g) exceeding that of commercial graphite and the currently available Ti-MXenes heterostructures. Overall, the obtained results shows that Ti-MXenes and their derivatives from phase transformation and heterostructures can provide promising pathways for effective implementation in energy applications.

Date of Award	Dec 2022
Original language	American English
Supervisor	KIN Liao (Supervisor)