Li Shouhu, Qiu Pengtao, Kang Jiaxin, Ma Yiming, Zhang Yichun, Yan Yigang, Jensen Torben R, Guo Yanhui, Zhang Jie, Chen Xuenian
Henan Key Laboratory of Boron Chemistry and Advanced Energy Materials, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan 453007, China.
Institute of New Energy and Low-Carbon Technology, Sichuan University, Chengdu 610207, China.
ACS Appl Mater Interfaces. 2021 Apr 21;13(15):17554-17564. doi: 10.1021/acsami.1c01659. Epub 2021 Apr 6.
Solid-state electrolytes based on -decaborates have caught increasing interest owing to the impressive room-temperature ionic conductivity, remarkable thermal/chemical stability, and excellent deformability. In order to develop new solid-state ion conductors, we investigated the influence of iodine substitution on the thermal, structural, and ionic conduction properties of -decaborates. A series of iodinated -decaborates, M[BHI] (M = Li, Na; = 1, 2, 10), were synthesized and characterized by thermal analysis, powder X-ray diffraction, and electrochemical impedance spectroscopy; the stability and ionic conductivity of these compounds were studied. It was found that with the increase of iodine substitution on the -decaborate anion cage, the thermal decomposition temperature increases. All M[BHI] exhibit an amorphous structure. The ionic conductivity of Li[BHI] is higher than that of the Li[BH] parent compound. An ionic conductivity of 2.96 × 10 S cm with an activation energy of 0.23 eV was observed for Li[BI] at 300 °C, implying that iodine substitution can improve the ionic conductivity. However, the ionic conductivity of Na[BHI] is lower than that of Na[BH] and increases with the increase of iodine substitution, which could be associated with the increase of the electrostatic potential, mass, and volume of the iodinated anions. Moreover, Li[BI] offers a Li-ion transference number of 0.999, an electrochemical stability window of 3.3 V and good compatibility with the Li anode, demonstrating its potential for application in high-temperature batteries.
基于十硼酸盐的固态电解质因其令人印象深刻的室温离子电导率、卓越的热/化学稳定性和出色的可变形性而受到越来越多的关注。为了开发新型固态离子导体，我们研究了碘取代对十硼酸盐的热、结构和离子传导性能的影响。合成了一系列碘化十硼酸盐M[B₁₀HₓI₁₀₋ₓ]（M = Li、Na；x = 1、2、10），并通过热分析、粉末X射线衍射和电化学阻抗谱对其进行了表征；研究了这些化合物的稳定性和离子电导率。结果发现，随着十硼酸盐阴离子笼上碘取代的增加，热分解温度升高。所有M[B₁₀HₓI₁₀₋ₓ]均呈现非晶态结构。Li[B₁₀HₓI₁₀₋ₓ]的离子电导率高于Li[B₁₀H₁₀]母体化合物。在300°C下，Li[B₁₀I₁₀]的离子电导率为2.96×10⁻⁵ S cm⁻¹，活化能为0.23 eV，这意味着碘取代可以提高离子电导率。然而，Na[B₁₀HₓI₁₀₋ₓ]的离子电导率低于Na[B₁₀H₁₀]，并随着碘取代的增加而增加，这可能与碘化阴离子的静电势、质量和体积的增加有关。此外，Li[B₁₀I₁₀]的锂离子迁移数为0.999，电化学稳定窗口为3.3 V，与锂阳极具有良好的相容性，表明其在高温电池中的应用潜力。
