综述分享：同步辐射X-射线技术在可充电池研究中的应用

随着社会信息化程度的迅速提高、电动汽车、可再生能源发电及智能电网的推广与快速发展，人们对动力/储能电池的需求日益增长，并对其性能提出越来越高的要求。开发高比能、高安全、长寿命及低成本二次电池对智能电网、新能源汽车等产业发展具有重要意义。

电池性能主要决定于电池材料的组成及结构。然而，电池系统的各种材料体系中, 多相多界面及动态反应特性使得电池储能机理的研究复杂且困难。近年来多种先进表征技术已被广泛运用于解析电池材料组成-结构-性能间构效关系，深刻揭示电池的储能机制。

同步辐射光源是一种先进的准直光源，具有强度高、波长连续可调、单色性好、有偏振性、分辨率高等独特优点。同步辐射光源在材料电子结构和几何结构（包括长程和短程结构）的分析上具有独特优势，并且可以方便地开展高时间和高空间分辨技术研究。

近年，同步辐射技术在电池电极材料构效关系及机理研究上得到广泛应用并解决了很多关键问题。尤其是具有高时间和高空间分辨同步辐射实时原位技术的应用，实现了电池的非破坏性实时动态研究，使得人们可以从更深的层次多尺度、多方位揭示电池储能机理。

Fig. 1. (a) Common synchrotron X-ray techniques and their applications in battery research, (b) schematic diagram of the electrochemical in situ XRD, (c) schematic diagram of the electrochemical in situ XAS.

本综述结合厦门大学杨勇教授课题组的研究成果, 详细介绍与评述同步辐射X-射线技术在电池研究中的应用，特别是原位X-射线衍射（XRD）、配对分布函数（PDF）、硬/软X-射线吸收光谱（XAS）和X-射线光电子能谱（XPS）技术的应用及特点，并重点介绍应用以上技术开展电池充放电过程电化学反应机理原位研究的一些实例。

电极材料中，客体离子的嵌入/脱嵌通常伴随着相转变过程，包括单相固体溶液转变、两相反应、有序-无序转变和结晶转变。充电-放电过程中的相转变性质对电极性能产生重要影响。 因此，理解电极材料的相转变对改进电池性能和解决充放电循环中的变形和应力等问题有重要意义。

锂离子电池中的层状氧化物：

Fig. 2. (a) Evolution of selected peaks from operando XRD data recorded on NCA during the first cycle, (b) a and c lattice parameters obtained from Rietveld refinements, and (c) galvano static charge–discharge (4.1–2.7 V, C/15, RT) curves.

锂离子电池中的聚阴离子化合物：

Fig. 3. (a–d) Evolution of the {200} reflection during C/5, 5C, 10C, and 60C charging. (e) Diffraction pattern at approximately 50% state of charge during C/5 charging. (f) Diffraction pattern at approximately 5% state of charge during 5C charging. (g, h) Diffraction patterns at approximately 50% state of charge during10 C and 60 C charging including two fits. 

Fig. 4. (a) Schematic representation of in situ synchrotron X-ray diffraction experimental setup. (b) Charging voltage curve (C/5) including the evolution of a 2D (200) LFP and (200) FP peak. (c) Active fraction and current density of the particles resulting from the average transformation times. (d) Sketch of the rate-dependent transformation upon charge as follows from the microbeam diffraction experiments.

钠离子电池中的层状氧化物：

Fig. 5. In situ XRD patterns collected during the first charge/discharge process of the O₃-type NaNi_0.5Mn_0.5O₂ (a) and NaLi_0.1Ni_0.35Mn_0.55O₂, (b) electrode, cycled at a current rate of 36 mA/g (λ = 0.6887 Å). 

Fig. 6. The observed synchrotron diffraction Bragg data of 75:25 LPS glass at room temperature (a). No intense peaks for r > 4.7 Å are observed in the corresponding Pair Distribution Functions (b).The short-range order is determined by the PS₄-tetrahedral first coordination sphere, which is very similar for all LPS glasses (c). Reflections at 245 °C could be assigned to β-Li₃PS₄ (d), which was used for the simulation of the PDF profile (e). The resulting profile difference (green line, e) was compared with the room temperature PDF data of the initial glass in the range of 0.5 Å  r 

Fig. 7. (a) The first derivative curves of in situ XANES spectra (black) and the linear combination fitting curves (red), obtained using the first derivative XANES curves of Cu₃(PO₄)₂ (x = 0) and Li₆Cu₃(PO₄)₂ asstandards. (b) Discharge/charge profiles and fitting results (coordination numbers and bond lengths) for Cu–O and Cu–Cu from the in situ EXAFS data. 

Fig. 8. (a) XANES spectra and (b–d) chemical statemaps for the LiFePO₄ cathode during charging obtained by ex situ XAFS imaging measurements. The successive maps obtained by in situ XAFS imaging are shown in (e).

Fig. 9. O K-edge XAFS spectra of Li_1.16Ni_0.15Co_0.19Mn_0.50O₂ electrode during the reversible 1st and 2nd cycle processes. They are obtained in (a) TEY and (b) PFY mode. The pre-edge structures are expanded in (c) TEY and (d) PFY mode.

本文源自微信公众号：JEnergyChem

原文标题：《厦门大学杨勇教授综述：同步辐射X-射线技术在可充电池研究中的应用》

原文链接：https://mp.weixin.qq.com/s/g2ayjH2UDMhOZwFzmXcQrQ