Improvement of high current performance of Li ion batteries with TiO2 thin film anodes by transition metal doping

Abstract

Radio-frequency magnetron sputtering technique was employed to deposit transition metal doped TiO2 thin film electrodes on polished stainless steel substrates. Rutile phase TiO2 films have been deposited with 6% and 10% Fe, Mn and Co doping and separate coin cell type Lithium Ion Batteries (LIB’s) have been prepared with these samples as anodes. LIB’s with the doped thin film samples have marked very high charge storage capacities at high current rates, which are in some cases better than that obtained with pristine TiO2 electrode. Further, among the three dopants the performance of the Fe doped samples are the best over a large no. of cycles. During the cycling test, 10% Fe doped TiO2 electrode has marked very high specific capacity of 0.524 mAh cm−2μm−1 after 1000 cycles at low current rate of 0.13 mA cm−2 and of 0.264 mAh cm−2μm−1 after 500 cycles even at high current rate of 1.3 mA cm−2. Increase in the current rate by 10 folds has not affected the specific capacity much, manifesting excellent response of the battery at high current rate. In the present study we have applied Fe, Co and Mn doping to TiO2 electrodes prepared under identical conditions and have compared their performances as anodes of thin film LIB’s in detail and thus the results would be very useful in technological realization of these anodes in practical LIB systems.