Na⁺-containing B-type carbonate apatite ([Ca_10−xNa_2x/3][(PO₄)_6−x(CO₃)_x][(OH)_2−x/3(H₂O)_x], BCA) is a hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂, HA)-derived compounds in which PO₄³⁻ sites of HA are partially replaced with CO₃²⁻. When CO₃²⁻-composition x exceeds 1, the ionic conductivity of BCA increases four orders of magnitude greater than that of HA, achieving values between 10⁻⁴–10⁻³ S cm⁻¹ at 600–800 °C. Owing to this unique compositional dependence of ionic conductivity, BCA is not only an important biomaterial, but also a promising material for solid electrolytes. Hence in this study, motivated by the elucidation of the ion conduction mechanism of BCA, two types of BCAs with different x values were prepared, and their physical and ionic conductive properties were investigated. Thermogravimetric analysis result of BCAs sintered under CO₂ (S-BCAs) showed that dissociation of CO₃²⁻ ions began at approximately 600 °C during heating in air. However, during three cycles of impedance measurements repeated from room temperature to 850 °C, the decrease in the x (up to −60 %) did not significantly affect the conductivity. The impedance measurements also revealed that the slope of the Arrhenius plot for conductivity exhibited a bend between 500 and 800 °C, which appeared repeatedly across measurement cycles. Based on first-principles calculations regarding the stable structure of the BCA, some OH⁻ (or O²⁻ in OH⁻ sites) might get trapped at the oxygen vacancy close to CO₃²⁻, and a defect association could form between Na⁺ and CO₃²⁻. Thus, the unique conductivity behavior observed in S-BCAs can be attributed to the changes in the carrier density and conduction pathways, which are influenced by the thermally induced change in the O²⁻-trapping state at oxygen vacancies close to CO₃²⁻.

An electrochemical synthesis of 3,5-bis(acyl)-1,2,4-thiadiazoles by the oxidative dimerization of α-oxothioamides with assistance of tetra-n-butylammonium iodide (TBAI) as electrolyte and mediator under constant current electrolysis (CCE) is reported. Herein, this approach is an example for S–N bond construction through the electrochemical method. Furthermore, the required intermediates α-oxothioamides are synthesized by the reaction of α-oxodithioesters with ammonium chloride in the presence of sodium acetate. The probable mechanism for the formation of final products is also presented. This strategy resulted in good to excellent yields of title compounds.

We investigated the effect of adding Fe and F in the synthesis of zirconium oxide-based cathode precursors to enhance the catalytic activity in the oxygen reduction reaction (ORR) in acidic media. In particular, we focused on adding F, and an ORR onset potential of 0.88 V was achieved by optimizing the amount of F added and heat treatment conditions contrary to a reversible hydrogen electrode. Additionally, a positive linear relationship was observed between the ORR onset potential and integrated intensity ratio of the monoclinic phase of ZrO₂ in the catalysts. This suggests that the monoclinic phase is fundamentally involved in the formation of active sites in the ORR in zirconium oxide-based cathodes.

For the coupling problems of lithium-ion batteries, a key issue at hand is that it is still unclear which mechanical failures can cause degradation and how, which is particularly salient at the electrode level. In this work, the correlation between electrode-level cracks and cycling capacity of silicon electrodes is investigated. Unexpectedly, for cracks in active layers, the capacity decreases with the increase of crack width, while the connection of other crack features to the capacity is weaker or even absent. Meanwhile, the modeling results, however, suggest that the increase in crack width cannot directly cause the capacity fading. To explain these results, the relationship between electrode debonding and active layer crack opening is also described quantitatively. By combining the debonding model and the porous electrode model, the connection between crack widths of active layers and capacity fading is clarified, and accurate predictions are obtained. These results indicate that the easily measurable width of active layer cracks is qualified to evaluate degradation, while the electrode debonding is in fact the direct cause of capacity fading. The findings in this work provide a more precise understanding of the degradation mechanism in lithium-ion battery electrodes.

Highly concentrated ionic liquid electrolytes (ILEs) have garnered considerable attention because of the safety of Li metal batteries. However, the use of highly concentrated electrolytes including ILEs is limited by the low affinity to separators. The separator directly contacts the surface of the Li metal anode, which significantly affects the morphology of deposited Li metal. In this study, a three-dimensionally ordered macroporous polyimide (3DOM PI) was proposed as a high-affinity separator for highly concentrated ILE ([lithium bis(fluorosulfonyl)imide]₁[N-methyl-N-propylpyrrolidinium bis(fluorosulfonyl)imide]₁). The 3DOM PI separator is made of polyimide and has a high porosity with a 3D-ordered uniform pore structure. These properties resulted in a higher affinity for highly concentrated ILE and higher ionic conductivity compared with that of conventional separators, making it possible to improve the reversibility of Li deposition/dissolution and the rate capability of the full cells. Moreover, the 3DOM PI separator improved the uniform Li deposition/dissolution and enabled the non-dendritic deposition of Li metal. The 3DOM PI with ILE provided more stable Li metal deposition/dissolution (charge/discharge reaction).

This paper presents an innovative approach wherein mechanical alloying and mechanical cation-disordering techniques are combined to synthesize peculiar zinc silicide phosphide (ZnSiP₂) anode materials under controlled atmosphere. In this method, Zn atoms and P atoms are simultaneously incorporated into the parent Si crystal structure, resulting in A(II)_xB(IV)_yP_x+y solid solutions with precise control over nanodomain structures of mixed crystalline-amorphous phases. This distinctive nanoarchitecture of the ZnSiP₂ anode, featuring an amorphous ionic-conduction phase network, facilitates the smooth transport of Li⁺ ions, thereby enabling an exceptionally prolonged electrochemical cycling performance, surpassing 200 cycles. In this study, we attempted to unravel the microstructure of ZnSiP₂ using transmission electron microscopy (TEM). It was observed that when synthesized under an inert Argon atmosphere, the material formed a polycrystalline structure consisting of numerous nanocrystals (5–10 nm) assembled. Additionally, when attempts were made to reduce synthesis costs by conducting the synthesis under ambient atmospheric (Air) conditions, amorphous regions were generated. This amorphous region within the polycrystalline ZnSiP₂ microstructure represents a novel finding. The electrochemical impedance measurements and galvanostatic intermittent titration technique (GITT) analysis conducted in this study not only revealed but also characterized the enhanced cycling performance of this unique ZnSiP₂ anode structure.