The freezing/melting behavior of water confined in mesopores was evaluated by differential scanning calorimetry (DSC) using micropore-free SBA-15 materials with different pore sizes as model materials. We determined the mesoporous structure (pore size distribution, specific surface area, and pore volume) by using Ar gas adsorption/desorption measurements, and investigated the thickness dependence of nonfreezable pore water (t nf ) on pore size. The t nf value was calculated as the difference between the pore radius, calculated from an Ar adsorption isotherm using the nonlocal density functional theory (NLDFT) analysis, and the radius of ice crystals that formed in the mesopores during the DSC measurement. Several studies have reported t nf values ranging from 0.35 to 1.05 nm depending on the evaluation method, whereas the t nf value estimated for the SBA-15 used in this work was approximately 0.7 nm. The difference between the reported t nf values and the value obtained in this work is mainly due to an underestimation of the pore diameter by the method based on the classical Kelvin equation. After appropriate correction of the pore diameter, the reported t nf value agreed with our results.

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Studies on local conduction paths in composite electrodes are essential to the realization of high-performance sulfide all-solid-state lithium batteries. Here, we directly evaluate the electrical properties of individual LiNi1/3Mn1/3Co1/3O2 (NMC) electrode active material particles in composite positive electrodes by scanning probe microscopy (SPM) techniques. Kelvin probe force microscopy (KPFM) and scanning spreading resistance microscopy (SSRM) are combined. The results indicate that all NMC particles exhibit a charged state with increasing potential, but low electronic conduction paths exist at point of contacts of some NMC particles. Furthermore, the I–V characteristics measured by conductive atomic force microscopy (C-AFM) suggest that these specific NMC particles show low charge–discharge reactivity. The results of the SPM techniques indicate that poor conduction locally limits the charge–discharge reactivity of electrode active materials, leading to the degradation of battery performance. Such an SPM combination accelerates the morphological optimization of composite electrodes by facilitating the investigation of the intrinsic electrical properties of the electrodes.

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