Solution-Processed Li₂O–Al₂O₃/TiO₂ Nanolaminate Stacks Containing Mobile Lithium Ions and with Increased Breakdown Voltages

An aqueous solution approach has been utilized to prepare nanolaminates of TiO2 and ionically conductive Li2O–Al2O3 (LiAlO). This new approach utilizes low curing temperatures, resulting in fully oxidized films as demonstrated by Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy. The layered structures have been characterized by scanning electron microscopy, X-ray diffraction, and X-ray reflectivity. Incorporation of sufficiently thick (13 and 27 nm) ion blocking TiO2 layers into nanolaminate structures with LiAlO layers resulted in an increase in breakdown voltage by more than a factor of two, relative to LiAlO. Nanolaminate structures also preserve the large double layer capacitance of the ionically conductive layer. Increased breakdown strength coupled with large capacitances results in a doubling of ultimate charge storage capacity, illustrating how nanolaminates can be used to improve properties relevant for energy/charge storage applications.