Spray pyrolysis-deposited nanoengineered TiO 2 thick films for ultra-high areal and volumetric capacity lithium ion battery applications

Abstract

Abstract Energy storage technologies are sensitively dependent on electrode film quality, thickness and process scalability. In Li-ion batteries, using additive-free titania (TiO2) as electrodes, we sought to show the potential of spray pyrolysis-deposited nanoengineered films with thicknesses up to 135 μm exhibiting ultra-high areal capacities. Detailed electron microscopic characterization indicated that the achieved thick films are composed of highly crystalline anatase TiO2 particles with sizes on the order of 10–12 nm and porous as well. A 135 μm thick film yielded ultra-high areal and volumetric capacities of 3.7 mAh cm−2 and 274 mAh cm−3, respectively, at 1C rate. Also the present work recorded high Coulombic efficiency and good cycling stability. The best previously achieved capacities for additive-free TiO2 films have been less than 0.25 mAh cm−2 and With additives, best reported areal capacity in the literature has been 2.5 mAh cm−2 at 1C rate, but only with electrode thickness as high as 1400 μm. Formation of through-the-thickness percolation of Ti3+ conductive network upon lithiation contributed substantially for the superior performance. Spray pyrolysis deposition of nanoparticulate TiO2 electrodes have the potential to yield volumetric capacities an order of magnitude higher than the other processes previously reported without sacrificing performance and process scalability.