Effect of the Interaction between Transition Metal Redox Center and Cyanide Ligand on Structural Evolution in Prussian White Cathodes.

Transition metal (TM) based Prussian whites, comprising a cyanide anion ((C≡N)-) and TM cations in an alternative manner, have been widely adopted as cathode materials for rechargeable batteries. Prussian whites are characterized by the TM electronic states that exclusively adopt low spin (LS) toward the C atom and high spin (HS) toward the N atom through the hybridized covalent bonding in the TM─C≡N─TM unit with the average oxidation states of the TM ions being 2+, considerably affecting the phase transition behavior upon the release and storage of carrier ions; however, there have been only a few studies on their associated features. Herein, Prussian whites with different HS TM ions were synthesized via coprecipitation and the phase transition behavior controlled by the π electron interaction between the cyanide anions and TM ions during battery operations was investigated. In situ X-ray characterizations reveal that the combined effect of π backdonation in the LS Fe-C unit and π donation in the HS TM-N unit effectively controls the bond length of the TM─C≡N─TM building unit, thus markedly influencing the lattice volume of a series of Prussian white cathodes during the charge/discharge process. This study presents a comprehensive understanding of the structure-property relationship of the Prussian white cathodes involving π electron interactions during battery operations.

Structural Evolution of Mg-Doped Single-Crystal LiCoO2 Cathodes: Importance of Morphology and Mg-Doping Sites.

Layered lithium cobalt oxide (LiCoO2, LCO), which serves as a structural motif for the widely adopted layered cathodes in lithium-ion batteries, has a long history, and its unstable phase transition during high-voltage operation (∼4.5 V) remains an intractable problem. Many research strategies, such as surface coating and immobile ion doping, have been proposed to address this issue, but a clear understanding of the effects has not been demonstrated because of various potential parameters (e.g., particle size, shape, and dopant content). Herein, we report a molten salt synthesis method that produces sphere-like single-crystal magnesium (Mg)-doped LCO. In situ X-ray diffraction and X-ray absorption fine structure analyses confirmed that the lattice strain was effectively alleviated by the effects of both the particle shape and Mg doping compared to the plate-like and sphere-like single-crystal LCO samples. Furthermore, the preference for Mg doping in the Co site (3b) rather than in the Li site (3a) in the LCO framework is systematically revealed, and a clear understanding of Mg doping that suppresses the monoclinic phase transition is discussed in detail.

LiNi0.5Mn1.5O4 Cathode Microstructure for All-Solid-State Batteries.

Solid-state batteries (SSBs) have received attention as a next-generation energy storage technology due to their potential to superior deliver energy density and safety compared to commercial Li-ion batteries. One of the main challenges limiting their practical implementation is the rapid capacity decay caused by the loss of contact between the cathode active material and the solid electrolyte upon cycling. Here, we use the promising high-voltage, low-cost LiNi0.5Mn1.5O4 (LNMO) as a model system to demonstrate the importance of the cathode microstructure in SSBs. We design Al2O3-coated LNMO particles with a hollow microstructure aimed at suppressing electrolyte decomposition, minimizing volume change during cycling, and shortening the Li diffusion pathway to achieve maximum cathode utilization. When cycled with a Li6PS5Cl solid electrolyte, we demonstrate a capacity retention above 70% after 100 cycles, with an active material loading of 27 mg cm-2 (2.2 mAh cm-2) at a current density of 0.8 mA cm-2.

High-Performance and Simply-Synthesized Ladder-Like Structured Methacrylate Siloxane Hybrid Material for Flexible Hard Coating.

A high performance ladder-like structured methacrylate siloxane hybrid material (LMSH) was fabricated via simple hydrolytic sol⁻gel reaction, followed by free-radical polymerization. A structurally ordered siloxane backbone, the ladder-like structure, which is an essential factor for high performance, could be achieved by a short period of sol⁻gel reaction in only 4 h. This results in superior optical (Transmittance > 90% at 550 nm), thermal (T5 wt % decomposition > 400 ℃ ), mechanical properties(elastic recovery = 0.86, hardness = 0.6 GPa) compared to the random- and even commercialized cage-structured silsesquioxane, which also has ordered structure. It was investigated that the fabricated ladder-like structured MSH showed the highest overall density of organic/inorganic co-networks that are originated from highly ordered siloxane network, along with high conversion rate of polymerizable methacrylate groups. Our findings suggest a potential of the ladder-like structured MSH as a powerful alternative for the methacrylate polysilsesquioxane, which can be applied to thermally stable and flexible optical coatings, even with an easier and simpler preparation process.

Ultrastructural changes of the gemifloxacin on Achilles tendon in immature rats: comparison with those of ciproxacin and ofloxacin.

Gemifloxacin is a synthetic fluoroquinolone antimicrobial agent that exhibits potent activity against most Gram-negative and Gram-positive organisms, and has a comparatively low chondrotoxic potential in immature animals. This study examined the effects of gemifloxacin on the Achilles tendons in immature Sprague-Dawley rats treated by oral intubation once daily for 5 consecutive days from postnatal week 4 onward at doses of 0 (vehicle), and 600 mg/kg body weight. Ofloxacin or ciprofloxacin were used for comparison. The Achilles tendon specimens were examined by electron microscopy. In comparison with the vehicle-treated controls, there were ultrastructural changes in all samples from the gemifloxacin-, ofloxacin-, and ciprofloxacin-treated rats. Degenerative changes were observed in the tenocytes, and the cells that detached from the extracellular matrix were recognizable. The degree of degenerative changes and the number of degenerated cells in the Achilles tendon were significantly higher in the treated group than in the control group. Moreover, among the quinolone-treated groups, these findings were most significant in the ofloxacin-treated group, and least significant in the gemifloxacin-treated group. It is unclear what these findings mean with respect to the possible risk in juvenile patients treated with gemifloxacin or other quinolones. However, these results show that gemifloxacin causes less changes in the connective tissue structures.