No abstract

A solid-electrolyte interphase (SEI) is widely recognized to improve the safety and durability of lithium ion batteries. In this work, we investigate the structure and chemistry of the carbon electrode and SEI in operando during two-cycle battery operation for further understanding of the electrochemical reactions, and the effect of the hysteresis using in situ neutron reflectivity (NR) and ex situ hard X-ray photoelectron spectroscopy (HAXPES). The results revealed the structural evolution of the electrode and SEI layer, such as the change in the thickness and scattering length density (SLD) in connection with the chemical composition during the lithiation/delithiation processes. Next, the HAXPES results at the point before and after the charging/discharging process revealed the change in the chemical composition of the SEI layer due to the chemical reactions on the formation/degradation. Based on the combination of these analyses, the results showed that the SLDs of the SEI layer evaluated by NR analysis were consistent with those determined by HAXPES. Concerning the difference in the first and second cycles, the structure of the amorphous carbon electrode exhibited hysteresis due to lithiation/delithiation, whereas the chemical composition of the SEI layer after charge/discharge was almost independent of the number of cycles.

A simple and versatile strategy has been employed to fabricate a "microreactor" consisting of nanoparticles encapsulated in a hollow core of monodispersed mesoporous silica shell. First, based on our synthesis method for monodispersed silica spheres with radially aligned mesopores, hollow mesoporous silica spheres have been synthesized using amino modified polystyrene beads as a template. We then found that introduction of metal oxide precursor into the mesoporous silica spheres using the incipient wetness technique leads to selective formation of nanoparticles into the core of the hollow spheres. Using this strategy, inorganic nanoparticles (TiO 2 and Fe 2 O 3 ) are confined into the hollow cores, with high loading and high dispersion, to which widely accessible mesoporous channels were connected. The loading contents of TiO 2 and Fe 2 O 3 were 40.2 and 36.4 wt %, respectively. These values were considered quite high when compared to values previously reported for similar materials. The photocatalytic activity of TiO 2 encapsulated silica capsules in the degradation of methyl orange was examined. The decomposition rate, especially at the initial reaction stage, for this capsule was considerably faster than that for other mesoporous silica-based TiO 2 /SiO 2 composites. The methodology described here is versatile and convenient and thus can be extended to a broad range of guest species for high-performance catalysis, adsorption, and energy conversion materials.

In this paper, we report on the pore expansion of monodispersed mesoporous silica spheres (MMSS) by a swelling agent incorporation method, by which swelling agents such as various hydrocarbons were incorporated into mesopores. Mesopores were expanded to more than twice the size (5.5 nm) of the original one (2.5 nm). In this method, pore expansion of MMSS was achieved while radially ordered hexagonal mesopores with spherical morphology and high monodispersity were retained. In addition, we have successfully obtained highly monodispersed porous FePtsMMSS composites by incorporating FePt precursors into the pore-expanded MMSS. The composites had both ferromagnetic behavior with coercivity of 3.3 kOe at room temperature and mesoporosity with pore volume of 0.74 cm 3 g -1 , which is enough to incorporate a variety of chemicals, nanoparticles, and proteins, such as drugs, quantum dots, enzymes, and DNA molecules. They have potential applications in drug delivery systems, gene delivery systems, magnetic hyperthermia treatments, and magnetic photonic crystals.

By adapting a novel surfactant exchange method, in which surfactants inside mesopores are completely exchanged by surfactants with longer alkyl chain lengths, pore-expansion of monodisperse mesoporous silica spheres (MMSS) with radially ordered hexagonal regularity was attained while retaining spherical morphology and high monodispersity.