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电化学(中英文)

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锂离子电池正极材料原位漫反射光谱电化学研究

陈露露,李浩冉*,刘维祎,王伟*   

  1. 生命分析化学国家重点实验室,南京大学化学化工学院,南京 210023
  • 出版日期:2024-02-23 发布日期:2024-02-23
  • 通讯作者: 王伟 E-mail:wei.wang@nju.edu.cn
  • 作者简介:陈露露,李浩冉,刘维祎,王伟

In Situ Diffuse Reflectance Spectroelectrochemistry of Cathode Materials in Lithium-ion Batteries

Lu-Lu Chen, Hao-Ran Li*, Wei-Yi Liu, Wei Wang*   

  1. State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering Nanjing University Nanjing 210023, China
  • Published:2024-02-23 Online:2024-02-23
  • Contact: Wei Wang E-mail:wei.wang@nju.edu.cn
  • About author:Lu-Lu Chen, Hao-Ran Li, Wei-Yi Liu, Wei Wang

摘要: 发展原位电化学光谱方法对深入研究电化学反应机理,并最终提高电池性能有着重要价值。建立在这一认识之上,能够应用于电池体系的原位光谱电化学表征技术被认为是表征电池电极材料性能的有效方法。但是受限于电池严格密封的不透明外壳和当前商用电池体系严格隔绝水氧的客观要求,开发更贴近真实电池工作条件的原位光谱电化学表征技术仍有较大需求。基于此,本文设计了一种基于传统纽扣电池架构的原位电化学池,该装置通过特殊设计实现了在尽可能模拟电池工作环境的前提下拥有透明的上盖,从而使发生电化学反应的同时进行光学检测成为可能。利用这一电化学池,本文以锂离子电池中常用的正极材料LiFePO4 (LFP)、NCM811 和 LiCoO2 (LCO) 为例,对其电化学反应过程中的漫反射光谱进行了采集和分析。相关数据定量地揭示了不同种类电极材料在一般反射光路架构下对不同波长可见光的响应关系,并能够直接用于对单色光检测场景下的波长优化提供指导和依据。更进一步,本文还对不同材料在充放电过程中的光谱特征进行了定量分析,揭示了其光谱特征同材料内在能级状态间的相关性。综上,本文提出了一种基于漫反射光谱的原位光谱电化学表征方法,作为对光谱电化学应用于电池体系的有效补充,本方法能够为评估电极材料性能提供一种全新且简单直接的途径,并最终助力电池性能的提升。

关键词: 锂离子电池, 漫反射光谱电化学, 原位, 正极材料

Abstract: Developing in situ spectroelectrochemistry methods, which can provide detailed information about species transformation during electrochemical reactions, is very important for studying electrode reaction mechanisms and improving battery performance. Studying real-time changes in the surface of electrode materials during normal operation can be an effective way to assess and optimize the practical performance of electrode materials, thus in situ and in operando characterization techniques are particularly important. However, batteries are hard to be studied by in situ characterization measurements due to their hermetically sealed shells, and there is still much room for battery characterization. In this work, a specially designed battery based on the structure of coin cells, whose upper cover was transparent, was constructed. With such a device, acquisition of diffuse reflectance spectra of electrode materials during charging and discharging was realized. This not only provided a simple measurement accessory for diffuse reflectance spectroscopy (DRS), but also complemented in situ characterization techniques for batteries. Taking commonly used cathode materials in lithium-ion batteries (LIBs), including LiFePO4 (LFP), NCM811 and LiCoO2 (LCO) as examples, we managed to find out the response relationships of different electrode materials to visible light of different wavelengths under ordinary reflectance illumination conditions. Heterogeneity of different cathode materials on interaction relationships with the lights of different wavelengths was also revealed. This work demonstrated the capability of guiding wavelength selection for different materials and assessing electrochemical performances of in situ diffuse reflectance spectroelectrochemistry. By combining electrochemistry with diffuse reflectance spectroscopy, this work made an effective complementary for spectroelectrochemistry.

Key words: Lithium-ion battery, Diffuse reflectance spectroelectrochemistry, In situ, Cathode materials