物理化学学报 >> 2020, Vol. 36 >> Issue (11): 2001048.doi: 10.3866/PKU.WHXB202001048

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利用固态核磁共振研究100LiO1/2-(100-x)PO5/2-xTeO2快离子导电玻璃的结构

张宗辉1,2, 任进军1,2,*(), 胡丽丽1,2,*()   

  1. 1 中国科学院上海光学精密机械研究所,高功率激光单元技术实验室,上海 201800
    2 中国科学院大学,材料与光电研究中心,北京 100049
  • 收稿日期:2020-01-19 录用日期:2020-02-19 发布日期:2020-03-09
  • 通讯作者: 任进军,胡丽丽 E-mail:renjinjunsiom@163.com;hulili@siom.ac.cn
  • 基金资助:
    国家自然科学基金(61675218);中国科学院百人计划资助项目

Structure Investigations on 100LiO1/2-(100-x)PO5/2-xTeO2 Fast Ionic Conducting Glasses Using Solid-State Nuclear Magnetic Resonance Spectroscopy

Zonghui Zhang1,2, Jinjun Ren1,2,*(), Lili Hu1,2,*()   

  1. 1 Key Laboratory of Materials for High Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, P. R. China
    2 Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
  • Received:2020-01-19 Accepted:2020-02-19 Published:2020-03-09
  • Contact: Jinjun Ren,Lili Hu E-mail:renjinjunsiom@163.com;hulili@siom.ac.cn
  • Supported by:
    the National Natural Science Foundation of China(61675218);the 100 Talents Program of Chinese Academy of Sciences

摘要:

改性的磷酸盐玻璃具有高离子电导率,可作为固体电解质或正极材料被应用于全固态电池中。快离子导电玻璃的性能与玻璃网络结构密切相关。然而,以往的研究主要集中于通过调整玻璃组分来改善离子电导率,对快离子导电玻璃的结构研究较少。磷酸盐离子导电玻璃的结构研究有助于理解结构与组分之间的关系,这对于改善离子电导率和开发新型离子导电玻璃具有重要意义。本工作制备了100LiO1/2-(100-x)PO5/2-xTeO2 (x = 0, 10, 20, 25, 30)体系的磷酸盐离子导电玻璃。利用拉曼光谱和固态核磁共振(SSNMR)技术深入地研究了其玻璃网络结构。其中,拉曼光谱和31P魔角旋转核磁共振(MAS NMR)谱表明,当x = 0时,大部分磷基团均为Q0Te(2)结构,而Q0Te(1)结构的含量可以忽略不计,其中QmTe(n)代表周围具有n个桥氧(P—O—P和P—O—Te连接中的氧原子均为桥氧)的磷基团,并且有m个Te原子与该[PO4]四面体连接。当PO5/2逐渐被TeO2取代时,P—O—P长链断开成短链,Q0Te(2)结构逐渐转变成Q1Te(2)和Q0Te(1)结构。二维的refocused INADEQUATE实验证明,没有孤立的磷结构单元产生,Q0Te(2)、Q1Te(2)和Q0Te(1)三种结构单元通过P—O—P相互连接。125Te WURST-QCPMG谱显示玻璃网络中存在三配位和四配位两种Te结构单元。当TeO2含量较低时,以四配位Te为主。但随着TeO2含量提高,三配位Te所占比例逐渐增大而四配位Te所占比例逐渐减小。根据31P与125Te谱的拟合结果,计算得到了玻璃样品中P—O—P、P—O—Te和Te—O—Te三种连接的实际含量,同时采用随机分布概率模型计算得到这种三种连接的理论含量,通过对比理论值和实验值发现,对于同核的P—O—P与Te—O—Te连接,其含量的实验值比理论值略高,而异核P—O—Te连接的含量的实验值比理论值稍低,这说明玻璃具有微弱的同核优先连接倾向。在本玻璃体系中,相对于碲氧多面体,Li+离子更倾向于聚集在[PO4]四面体周围,但仍然有部分Li+离子进入到Te周围,形成[TeO3]结构。在TeO2取代PO5/2的过程中,这些玻璃样品中桥氧的比例几乎没有变化,导致玻璃化转变温度随着TeO2含量增加而基本保持不变。本文对不同组分玻璃样品的网络结构进行了全面的描述,这对离子导电玻璃的性能改进和新型玻璃正极材料的开发具有重要意义。

关键词: 磷碲酸盐玻璃, 固态核磁共振, 快离子导体, 玻璃结构, 拉曼光谱

Abstract:

Modified phosphate glasses can be used in all-solid-state batteries as solid electrolytes and cathodes due to their high ionic conductivity. The properties of fast ionic conducting glasses are strongly related to the structure of the glass networks. However, most previous works have focused on improving the ionic conductivity of such glasses by composition adjustments, while structural studies are scant. Structural investigations are essential to understand the composition dependence of the glass structure, which is valuable for improving the ionic conductivity and developing new ionic conducting glasses. In this work, phosphate ionic conducting glasses with compositions of 100LiO1/2-(100-x)PO5/2-xTeO2 (x = 0, 10, 20, 25, 30) were synthesized, and their structures were investigated using Raman and solid-state nuclear magnetic resonance (SSNMR) spectroscopy. When x = 0, Raman and 31P magic angle spinning (MAS) NMR spectra showed that most of the phosphorus species were Q0Te(2) species, while the concentration of Q0Te(1) species was negligible. QmTe(n) represents the phosphorus species with n bridging oxygen atoms (the oxygen atoms in P—O—P and P—O—Te linkages are both considered to be bridging oxygen atoms), and m Te atoms are connected to this [PO4] tetrahedron. When PO5/2 is substituted with TeO2, long P—O—P chains are broken into short chains, and Q0Te(2) species gradually transform into Q1Te(2) and Q0Te(1) species. Two-dimensional (2D) refocused incredible natural abundance double quantum transfer experiment (INADEQUATE) spectra proved that no isolated phosphorus species existed in the glasses; Q0Te(2), Q1Te(2), and Q0Te(1) species were connected with each other through P—O—P linkages. Three- and four-coordinated Te were observed in the static 125Te wideband uniform-rate smooth truncation quadrupolar Carr-Purcell-Meiboom-Gill (WURST-QCPMG) spectra. When the concentration of TeO2 was low, four-coordinated Te was dominant. However, with the increase in TeO2, the proportion of three-coordinated Te gradually increased, while that of four-coordinated Te decreased. The experimental contents of P—O—P, P—O—Te, and Te—O—Te linkages in these glasses were calculated from the deconvolutions of 31P and 125Te NMR spectra. Then, the experimental contents were compared with the theoretical contents calculated according to a random distribution model. It was found that the experimental contents of homonuclear P—O—P and Te—O—Te linkages were slightly higher than their corresponding theoretical values, while the experimental content of heteronuclear P—O—Te was slightly lower than the theoretical value. These results indicated a weak priority for homonuclear connectivities. In this glass system, Li+ ions preferred to stay around [PO4] tetrahedrons rather than tellurium oxygen polyhedrons. However, a small number of Li+ ions still interacted with tellurium oxygen polyhedrons to form [TeO3] units. During the substitution of PO5/2 by TeO2, the fractions of bridging oxygen atoms in these glasses were almost unchanged, resulting in a slight change in the glass transition temperature. This work provides a comprehensive description of glass networks, depending on their compositions, which could be valuable for improving the ionic conductivity and for designing new fast ionic conducting glasses through structural modifications.

Key words: Phosphotellurite glass, Solid-state NMR, Fast ionic conductor, Glass structure, Raman spectrum

MSC2000: 

  • O641