Current lithium‐ion battery technology is gearing towards meeting the robust demand of power and energy requirements for all‐electric transportation without compromising on the safety, performance, and cycle life. The state‐of‐charge (SOC) of a Li‐ion cell can be a macroscopic indicator of the state‐of‐health of the battery. The microscopic origin of the SOC relates to the local lithium content in individual electrode particles and the effective ability of Li‐ions to transport or shuttle between the redox couples through the cell geometric boundaries. Herein, micrometer‐resolved Raman mapping of a transition‐metal‐based oxide positive electrode, Li1‐x(NiyCozAl1‐y‐z)O2, maintained at different SOCs, is shown. An attempt has been made to link the underlying changes to the composition and structural integrity at the individual particle level. Furthermore, an SOC distribution at macroscopic length scale of the electrodes is presented.

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We used in situ spectroscopic ellipsometry to measure the photocatalytic activity of titania films on fused silica and glass substrates. Amorphous and anatase TiO2 films with a variety of microstructures were prepared by reactive sputtering and pyrolytic deposition. The titania films were coated with thin, spin-cast films of stearic acid [CH3(CH2)16COOH] to represent an organic contaminant. Photooxidation rates were determined from ellipsometric measurements of the reduction in stearic acid film thickness during exposure to UV irradiation at 313 or 365 nm. The photooxidation rate was found to be proportional to I α, where I is the irradiance. The exponent α correlated with the TiO2 crystallinity, having values of approximately 0.7 and 0.8 for amorphous and anatase films, respectively. The largest photooxidation rate was observed for the pyrolytically deposited anatase sample on which X-ray reflectometry and spectroscopic ellipsometry measurements detected the presence of a low-density TiO2 surface layer. To assess the performance of these films in practical applications, the specimens were exposed to wavelength and irradiance conditions that simulated a solar UV spectrum. The most photocatalytically active sample had a stearic acid film removal rate of 22 nm/h, which would be suitable for self-cleaning window applications.

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To make a gas sensor suitable for use at high temperatures, we have used a sol-gel-processing technique to bond a copper-exchanged zeolite fluorescence indicator onto the end of an all-silica optical fiber. Experimental results from single-fiber prototype sensors show they can be used to measure either the oxygen concentration or the equivalence ratio for gas mixtures containing weak or strong reductants, respectively.