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

• A new method has been developed to deposit Li4Ti5O12 thin film electrodes.
• Deposited Li4Ti5O12 film electrodes combine a high storage capacity and excellent rate capability.
• 3D deposition of Li4Ti5O12 thin film by MOCVD has been investigated.
• Storage capacity was improved 2.5 times by applying 3D deposition.

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.