无机材料学报 ›› 2021, Vol. 36 ›› Issue (2): 152-160.DOI: 10.15541/jim20200144 CSTR: 32189.14.10.15541/jim20200144

所属专题: 电致变色材料与器件 功能材料论文精选(2021) 【虚拟专辑】电致变色与热致变色材料 电致变色专栏2021

• 专栏: 电致变色材料与器件(特邀编辑:刁训刚, 王金敏) • 上一篇    下一篇

WO3电致变色薄膜离子传输动力过程及其循环稳定性

周开岭(), 汪浩, 张倩倩, 刘晶冰, 严辉   

  1. 北京工业大学 材料科学与工程学院, 北京 100124
  • 收稿日期:2020-03-23 修回日期:2020-07-09 出版日期:2021-02-20 网络出版日期:2020-09-09
  • 通讯作者: 汪浩, 教授. E-mail: haowang@bjut.edu.cn
  • 作者简介:周开岭(1990-), 男, 博士研究生. E-mail: zkling@emails.bjut.edu.cn
  • 基金资助:
    北京市教委科技发展计划(KZ201710005009)

Dynamic Process of Ions Transport and Cyclic Stability of WO3 Electrochromic Film

ZHOU Kailing(), WANG Hao, ZHANG Qianqian, LIU Jingbing, YAN Hui   

  1. College of Materials Science & Engineering, Beijing University of Technology, Beijing 100124
  • Received:2020-03-23 Revised:2020-07-09 Published:2021-02-20 Online:2020-09-09
  • About author:ZHOU Kailing(1990-), male, PhD candidate. E-mail: zkling@emails.bjut.edu.cn
  • Supported by:
    Scientific and Technological Development Project of the Beijing Education Committee(KZ201710005009)

摘要:

电致变色WO3的离子传输动力学过程对其变色性能和循环稳定性具有重要的影响。离子传输过程涉及到WO3电极的结构变形、相转变等复杂过程, 导致通过传统的电化学阻抗谱很难进行有效研究。计时电位法是通过施加电流, 测量电极材料响应电位的一种电化学表征方法。与其它电化学表征方法(阻抗谱法和伏安法)相比, 该技术能够直接探测溶液-电极系统中不同状态下的电压分布, 并经常被用于研究电极系统中的物质传输动力学行为, 例如电极表面附近的质子吸附和传输现象。本工作采用计时电位技术研究和调控WO3薄膜中的离子传输行为, 结果表明: 大的Li+离子插入通量可拓宽WO3/电解质界面处离子的传输通道, 有助于离子传输动力和光响应速度的提升。然而, 反复的离子插入/抽出行为会通过“离子球磨效应”减小WO3/电解质界面处WO3晶粒的尺寸, 使得WO3薄膜的致密性增强, 阻碍离子传输和电解质渗透, 导致插入的Li+及反应产生的LixWO3在WO3结构中不可逆积累, 薄膜的光学调制幅度和电致变色活性明显下降。该工作为电极材料中离子传输动力学分析和离子传输行为控制提供了一种有效的方法。

关键词: WO3电致变色材料, 计时电位法, Li +插入通量, 离子传输动力过程

Abstract:

The dynamic process of ions transport in electrochromic WO3 film is usually studied by electrochemical impedance spectroscopy. However, the detailed features are hidden since the ions insertion into WO3 is a very complex process including structural deformation and phase transformations. Chronopotentiometry is an electrochemical characterization method that measures the response potential of a system under an imposed current. Compared to other dynamic characterization methods (impedance spectroscopy and CV), it allows direct access to the voltage contributions in different states of the solution-electrode system and has frequently been used to investigate kinetic effects such as adsorption and transport phenomena near electrode surface. In this study, chronopotentiometry is creatively applied to study ion transport kinetics and control ions insertion behavior in electrochromic WO3 film. The results suggest that a large ions insertion flux at the interface of WO3/electrolyte could broaden ions transport channels due to the fierce lattice expansion during Li+ions insertion process, which further improves the ions transportation kinetics and gifts a fast switching speed of optical performance. However, the repeating ions insertion/extraction behaviors at the interface of WO3/electrolyte for the long-term cycle process can reduce the size of WO3 grains as a “ball mill effect”. Especially, a large ions transport flux can aggravate the “ball mill effect”. Consequently, the structure of the WO3 film becomes very dense, which is unfavorable for ions transport and electrolyte permeation. This dense structure also leads to an irreversible accumulation of Li+ ions and LixWO3 in the WO3 host structure, resulting in a decay of optical modulation ability and electrochromic activity. This work offers an efficient method to analyze ion transport kinetics in intercalation materials and a new understanding of the relationship between ion transport behavior and cyclic stability of electrochromic materials.

Key words: WO3 electrochromic materials, chronopotentiometry, Li + insertion flux, ions transport dynamic process

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