Li + ion diffusion in Li 4Ti 5O 12 thin film electrode prepared by PVP sol–gel method

Abstract

Li 4Ti 5O 12 thin films for rechargeable lithium batteries were prepared by a sol–gel method with poly(vinylpyrrolidone). Interfacial properties of lithium insertion into Li 4Ti 5O 12 thin film were examined by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and potentiostatic intermittent titration technique (PITT). Redox peaks in CV were very sharp even at a fast scan rate of 50 mV s −1, indicating that Li 4Ti 5O 12 thin film had a fast electrochemical response, and that an apparent chemical diffusion coefficient of Li + ion was estimated to be 6.8×10 −11 cm 2 s −1 from a dependence of peak current on sweep rates. From EIS, it can be seen that Li + ions become more mobile at 1.55 V vs. Li/Li +, corresponding to a two-phase region, and the chemical diffusion coefficients of Li + ion ranged from 10 −10 to 10 −12 cm 2 s −1 at various potentials. The chemical diffusion coefficients of Li + ion in Li 4Ti 5O 12 were also estimated from PITT. They were in a range of 10 −11–10 −12 cm 2 s −1.