Amphiphilic aggregation at solid-liquid interfaces can generate mesostructured micelles that can serve as soft templates. In this study we have simulated the self-assembly of hexadecyltrimethylammonium chloride (C16TAC) surfactants at the Si(1 0 0)- and Si(1 1 1)-aqueous interfaces. The surfactants are found to form semicylindrical micelles on Si(1 0 0) but hemispherical micelles on Si(1 1 1). This difference in micelle structure is shown to be a consequence of the starkly different surface topographies that result from the reconstruction of the two silicon surfaces, and reveals that micelle structure can be governed by epitaxial matching even with non-polar substrates.
The establishment of an electrochemical-thermal coupling model for a lithium-ion battery (LIB) is an important issue in developing an appropriate thermal management system of LIB packs. In this paper, a novel thermal-coupled single particle model with few parameters is first developed to promote battery parameter identification at various temperatures. Then, after collecting the experimental profiles of battery voltage, current, and temperature, a multi-objective stepwise identification scheme based on genetic algorithm is proposed to identify the classified parameters of LIB at different temperatures. Finally, the proposed battery model and the stepwise parameter identification are validated in terms of the simulations and experiments. The results demonstrate that this proposed battery model and parameter identification method can not only describe inherent electrochemical and thermal characteristics of the battery, but also identify the battery electrochemical states with high precision, which provides a strong foundation for the development and implementation of battery thermal management system.
Although Li-ion battery technology has been identified as having great potential for energy storage, a lack of basic understanding of the structural and chemical evolution of the materials during the operation of the battery [1] is slowing the rate of battery development. Repeated charging and discharging of a Li-ion battery induces microstructural changes at the interface between the electrolyte and the electrode and within the electrode (active materials) due to Li migration. Although it has been established that this structural evolution of active materials is responsible for the failure of the battery, the mechanisms of the microstructural changes as a function of charging/discharging are not well understood.Advanced diagnostic tools such as electron microscopy along with other surface and bulk sensitive tools, often in ex-situ mode, have been used to probe materials changes. However, it is recognized that characterizing this interface using an ex-situ tools will present major challenges for materials and interfaces that are not stable upon exposure to air and many not be stable without the potentials and environmental conditions that occur during battery operation. Capabilities that enable the in situ observation of the structural and chemical changes during the dynamic operation of battery are needed for addressing this scientific challenge. The main objective the work reported is to develop the fundamental scientific understanding of the chemical and structural evolution at the interface between the electrolyte and the electrode as well as within the electrodes under the dynamic (Li charging and discharging) operating conditions. Electron energy-loss spectroscopy (EELS) in a TEM not only allows the direct detection of Li following the lithiation, but also provides information related to local electronic structure of the materials with a spatial resolution from several nanometers to single atomic column. EELS operated in a spectroscopic imaging mode will allow the mapping of the distribution of a specified chemical species with a spatial resolution of nanometer to atomic scale. In spite of the great interests in developing and characterizing novel materials for energy storage in battery applications, up to date EELS techniques have not been widely used to study the lithium insertion in electrode materials used in Li-ion batteries. For Li insertion into the lattice of TiO 2 , the detection of Li has been often carried out indirectly, mostly based on the phase and structural analysis. Direct detection of Li in the lattice of TiO 2 and investigation of the associated electronic structure changes due to the Li incorporation in TiO 2 has not been done.In this paper, we use TEM imaging, electron diffraction, and EELS to probe the microstructure and Li insertion, and to investigate the electronic structure of rutile TiO 2
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