Spray pyrolysis-deposited nanoengineered TiO2 thick films for ultra-high areal and volumetric capacity lithium ion battery applications

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 mu m 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)mu m 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 mu m. 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. (C) 2017 Elsevier B.V. All rights reserved.