Atomistic Insights into Lithium Storage Mechanisms in Anatase, Rutile, and Amorphous TiO₂ Electrodes

Area of Science:

• Materials Science
• Electrochemistry
• Computational Chemistry

Background:

• Titanium dioxide (TiO2) is a promising material for lithium-ion battery electrodes.
• Understanding lithium-ion diffusion and storage mechanisms in TiO2 is crucial for improving battery performance.

Purpose of the Study:

• To investigate lithium-ion diffusion and storage in crystalline and amorphous TiO2 using density functional theory.
• To explore phase transformations and interfacial charge-transfer reactions in Li-TiO2 systems.
• To guide the design of high-performance TiO2-based electrodes.

Main Methods:

• Density functional theory (DFT) calculations.
• Investigation of Li-TiO2 phase transformations (0 ≤ x ≤ 1).
• Analysis of solid-state Li+ diffusion and interfacial charge-transfer reactions.

Main Results:

• Amorphous TiO2 exhibits lower Li+ diffusion energy barriers than crystalline polymorphs, especially at higher Li+ concentrations.
• Li+ diffusion in amorphous TiO2 is facilitated by the filling of low-energy trapping sites and changes in chemical interactions.
• Amorphous TiO2 utilizes both surface and bulk Li+ storage mechanisms, while nanostructured crystalline TiO2 favors surface mechanisms.

Conclusions:

• Amorphous TiO2 demonstrates superior Li+ diffusivity and storage potential compared to crystalline TiO2.
• Nanostructuring crystalline TiO2 can enhance battery rate and capacity by promoting surface storage.
• These findings provide insights for optimizing TiO2 electrode design for advanced batteries.