Study on Li +-ion diffusion in nano-crystalline LiMn 2O 4 thin film cathode grown by pulsed laser deposition using CV, EIS and PITT techniques

Abstract

In the present work, LiMn 2O 4 thin films have been prepared by pulsed laser deposition on stainless steel substrates. The films deposited at 400 °C and 200 mTorr of oxygen were mainly composed of nano-crystals less than 100 nm and their agglomerates. Three different electrochemical methods including CV, EIS and PITT were applied to measure the overall Li +-ion diffusion coefficients and charge-transfer resistances at various potentials from 3.85 to 4.5 V. The Li + diffusion coefficients were in the range of 10 −12 to 10 −10 cm 2 s −1, depending on the potentials. It was found that the charge-transfer resistances decreased with the increase of potentials. Especially, relatively high diffusion coefficients and low charge-transfer resistances were observed above 4.2 V.