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金属锂具有高理论比容量和低还原电位, 是锂电池阳极的理想材料之一. 但在长期循环充放电过程中, 金属锂因锂枝晶生长会导致出现界面恶化及能量损失严重等问题, 对锂金属电极与电解质表界面反应的优化是一个重要研究方向. 本文介绍了锂枝晶产生的危害, 从分析及抑制锂枝晶沉积两方面综合评述了为解决这一问题所采取的方法, 包括固态电解质界面形成机制和保护机理、 表面改性、 三维锂阳极和液态/固态电解质等方法, 总结了各种方法的优劣势, 并展望锂金属电池在能源领域的研究前景. 相似文献
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介绍了一种先冷冻干燥后固相烧结制备正极材料Li2FeP2O7的方法. 利用X射线衍射(XRD)、 扫描电子显微镜(SEM)、 透射电子显微镜(TEM)和傅里叶变换红外光谱(FTIR)对材料的组成和形态进行表征, 并通过循环伏安曲线(CV)和电化学阻抗谱(EIS)研究了Li2FeP2O7材料的电化学性能. 研究发现, 合成Li2FeP2O7的最佳温度为590 ℃, 此温度下反应较完全且产物杂质较少, 1.6C倍率下的放电比容量达到55 mA·h·g?1, 明显高于其它温度下合成样品的放电比容量. 该温度下合成的Li2FeP2O7还具有低阻抗和较大的交换电流密度, 说明这种合成方式有利于提高锂离子在Li2FeP2O7中的扩散. 相似文献
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Effects of β‐nucleating agent and crystallization conditions on the crystallization behavior and polymorphic composition of isotactic polypropylene/multi‐walled carbon nanotubes composites 下载免费PDF全文
Jian Kang Jinghan He Zhengfang Chen Feng Yang Jinyao Chen Ya Cao Ming Xiang 《先进技术聚合物》2015,26(1):32-40
In this study, the effects of crystallization conditions (cooling rate and end temperature of cooling) on crystallization behavior and polymorphic composition of isotactic polypropylene/multi‐walled carbon nanotubes (iPP/MWCNTs) composites nucleated with different concentrations of β‐nucleating agent (tradename TMB‐5) were investigated by differential scanning calorimetry (DSC), wide‐angle X‐ray diffraction (WAXD) and scanning electronic microscopy (SEM). The results of DSC, WAXD and SEM revealed that the addition of MWCNTs and TMB‐5 evidently elevates crystallization temperatures and significantly decreases the crystal sizes of iPP. Because of the competition between α‐nucleation (provided by MWCNTs) and β‐nucleation (induced by TMB‐5), the β‐phase crystallization takes place only when 0.15 wt% and higher concentration of TMB‐5 is added. Non‐isothermal crystallization kinetics study showed that the crystallization activation energy ΔE of β‐nucleated iPP/MWCNTs composites is obviously higher than that of pure iPP, which slightly increases with the increase of TMB‐5 concentration, accompanying with the transition of its polymorphic crystallization behavior. The results of non‐isothermal crystallization and melting behavior suggested that the cooling rate and end temperature of cooling (Tend) are important factors in determining the proportion and thermal stability of β‐phase: Lower cooling rate favors the formation of less amount of β‐phase with higher thermal stability, while higher cooling rate encourages the formation of higher proportion of β‐phase with lower thermal stability. The Tend = 100°C can eliminate the β–α recrystallization during the subsequent heating and therefore enhance the thermal stability of the β‐phase. By properly selecting TMB‐5 concentration, cooling rate and Tend, high β‐phase proportion of 88.9% of the sample was obtained. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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Large-pore-size (150 nm) polystyrene (PSt) microspheres were carboxylated with phthalic anhydride (PA) through Friedel-Crafts acetylation to study the adsorption of 2,4,6-trinitrotoluene (TNT) on this material from aqueous solution. The scanning electron microscope (SEM) images and mercury porosimetry measurements (MPM) of the microspheres showed that the pore structure was unchanged during the reaction. High adsorption capacity (11.2 mg g−1 of suction-dried adsorbent) and adsorption rate (33.9 mg g−1 h−1) for TNT were observed during the study. As shown by the adsorption isotherm, the adsorption of TNT on PA-PSt can be described by the Freundlich adsorption equation, indicating heterogeneous adsorption process. On-column adsorption of TNT on PA-PSt and elution indicated that TNT can be completely removed from aqueous solution and condensed into acetone. 相似文献
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A kind of ferroelectrics-ferromagnet mixed ceramics material which ∈≈μ=75 to 80 has been prepared successfully. The original ferroelectrics and ferromagnet materials and the mixed ceramics material have been studied by means of Mössbauer spectroscopy, etc. Mössbauer study indicated the presence of a relaxation effect in the mixed ceramics and the differences of Mössbauer parameters, especially, the hyperfine field distributionsP(H) between the mixed ceramics and the original ferromagnet materials. These results showed that complicated hyperfine interactions exist in mixed ceramics. The sintering temperature has an effect on the cation distribution in mixed ceramics. 相似文献
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Yufang Zheng Zhengfang Yu Z. N. Liang Yan Zhuang Fenen Hu 《Hyperfine Interactions》1992,68(1-4):169-172
The relations between the electrical characteristics of BaSn1?x Sb x O3 perovskite system and the contents of BaO, Sb2O3 and silicate sintering agent were studied by X-ray diffraction analysis and Mössbauer spectroscopy. It was found that the electrical conductivity is related to the substitution of Sb3+ for Sn4+, the content of sintering agent and the phase constitutents in samples. BaSnO3, Ba3Sn2O7, Ba2SnO4 and SnO2 phases might appear in different fractions when the contents of BaO change from 0.5 mole to 3.5 mole. In low antimony percentage condition, pentavalent Sb3+ ions inserted in Sn4+ sites and formed the donor center. In high antimony percentage (x≥0.20) condition, the existence of an insulating phase (BaSb2O6) was confirmed. 相似文献