Electrostatic spray deposition (ESD) is a technique recently developed for the fabrication of inorganic thin films. Several process steps involved in an ESD process are overviewed. A variety of surface morphologies of LiCoO, thin layers fabricated by this technique are presented, indicating correlations between the morphologies and deposition conditions.

We present a semimathematical model for the simulation of the impedance spectra of a rechargeable lithium batteries consisting of porous electrodes with spherical Li + intercalation particles. The particles are considered to have two distinct homogeneous phases as a result of the intercalation and deintercalation of Li + during charge and discharge. The diffusion of Li + ions in the two phases and the charge transfer at the solid electrolyte interface ͑SEI͒ are described with a mathematical model. The SEI and the electrolyte are modeled using passive electronic elements. First, this model is derived for a single intercalation particle consisting of two different solid phases. This model is then transformed to a continuous model and applied to a single porous electrode, where the sizes of the particles are assumed to have on average two grain sizes where the radii are Gaussian distributions. Finally, this model is further developed to simulate the impedance of a rechargeable lithium-ion battery. In general, aging of dynamic systems is a major concern and finding relevant aging mechanisms is then of vital importance. For batteries, many efforts have been undertaken in order to estimate the calendar life of these systems. In the case of the more recent Li-ion batteries, a lot of work was already performed within the Department of Energy's Advanced Technology Program ͑DoE-ATP͒. Electrochemical studies including impedance spectroscopy are widely used for that purpose. Unfortunately, these methods can only provide indirect proof of certain aging mechanisms. Therefore, additional research, such as postmortem analysis, is a prerequisite to determine the most relevant mechanisms that contribute to aging. Subsequently, these aging parameters then should be translated into electrochemical behavior that is monitored with electrochemical equipment. During the last decade, many aging mechanisms have been identified for Li-ion batteries. A wide overview that comprises cathode, anode, electrolyte, and current collectors is given in Ref.1. The present model uses a transformation of a complex model in the time domain into the frequency domain, which is typically the outcome of impedance spectroscopy. The aging then is introduced via typical aging parameters identified in Ref. 1. For the current calculations, the focus is on the positive electrode, as it has been reported recently that this electrode is the major source for aging. [2][3][4] The idea is to show the influence of potential sources of degradation on impedance with focus on aging, which may result in reduction of the particle size and changes in the particle size distribution, due for instance, to dissolution of material, and on changes in the solid electrolyte interface that may occur during the lifetime of a battery. Besides, when the system is subject to even small crystallographic changes, the diffusion coefficient may be altered as well.LiNiO 2 and LiCoO 2 are well-known compounds for use as positive electrodes in lithium secondary batteries because of their high ...

No abstract

No abstract