Lithiation Thermodynamics and Kinetics of Anatase TiO₂ Nanoparticles Having Varying Sizes: Implications for Nanosized Li-Intercalation Electrodes

Using TiO₂ as a model system, we reveal size-dependent thermodynamics and kinetics in Li-intercalation electrodes. Smaller particles have lower equilibrium potential (E_eq) and smaller entropy change during lithiation, which is 15.9 J K^-1 (mol Li)⁻¹ for the 10 nm sample and 34.7 J K^-1 (mol Li)⁻¹ for the 84 nm sample. Charge transfer energy barrier (E_a,ct) increases from 199.7 to 278.8 meV while resistance (R_ct) decreases with decreasing particle size from 84 to 10 nm, suggesting R_ct plays a more important role in determining the electrochemical performance. This study may guide the design of Li-intercalation electrodes with superior rate performance.