Planar and 3D deposition of Li₄Ti₅O₁₂ thin film electrodes by MOCVD

Abstract

Li₄Ti₅O₁₂ is well known to be a safe and efficient anode material for Li-ion batteries. A metal-organic chemical vapor deposition process has been developed for the synthesis of Li₄Ti₅O₁₂ thin film anodes on planar and 3D substrates. The influences of various deposition parameters, including precursor flow rates and post-annealing temperatures, have been investigated by material and electrochemical analyses. Li₄Ti₅O₁₂ thin films deposited at the optimized process parameters showed a high crystallinity and high electrochemical activity. A reversible storage capacity of 151 mAh/g was achieved at a current of 0.5 C, corresponding to 86.3% of the theoretical specific capacity of Li₄Ti₅O₁₂. Up to almost 600 cycles, the electrodes showed no significant capacity loss. Furthermore, the deposited thin film anodes also showed excellent rate performance. Compared to the storage capacity at 0.5 C, 93% of the capacity was maintained at 10 C. Thin films were also deposited on highly structured substrates to investigate the uniformity and electrochemical performance. With the same footprint area, the 3D Li₄Ti₅O₁₂ film anode showed a 2.5 times higher storage capacity than planar electrode.