Li+ ion diffusion in Li4Ti5O12 thin film electrode prepared by PVP sol–gel method

Abstract Li 4 Ti 5 O 12 thin films for rechargeable lithium batteries were prepared by a sol–gel method with poly(vinylpyrrolidone). Interfacial properties of lithium insertion into Li 4 Ti 5 O 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 4 Ti 5 O 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 4 Ti 5 O 12 were also estimated from PITT. They were in a range of 10 −11 –10 −12  cm 2  s −1 .