储能科学与技术

• 储能科学与技术 •    

全钒液流电池电解液容量衰减及草酸恢复研究

叶涛1(), 王怡君2, 唐子龙1(), 潘国梁2()   

  1. 1.清华大学材料学院，北京 100084
    2.上海国缆检测股份有限公司，上海 200444
  • 收稿日期:2024-09-09 修回日期:2024-10-16
  • 通讯作者: 唐子龙,潘国梁 E-mail:yet23@mails.tsinghua.edu.cn;tzl@tsinghua.edu.cn;panguoliang@ticw.com.cn
  • 作者简介:叶涛（1998—），男，博士研究生，研究方向为锂离子电池材料，E-mail：yet23@mails.tsinghua.edu.cn；
  • 基金资助:
    国家自然科学基金(52172210)

Investigation of Capacity Fading in Vanadium Flow Battery Electrolytes and Recovery via Oxalic Acid

Tao YE1(), Yijun LI2, Zilong TANG1(), Guoliang PAN2()   

  1. 1.School of Materials Science and Engineering, Tsinghua University, Beijing 100084, P. R. China
    2.Shanghai National Center of Testing and Inspection for Electric Cable and Wire Co. , Ltd, Shanghai 200444, P. R. China
  • Received:2024-09-09 Revised:2024-10-16
  • Contact: Zilong TANG, Guoliang PAN E-mail:yet23@mails.tsinghua.edu.cn;tzl@tsinghua.edu.cn;panguoliang@ticw.com.cn

摘要：

全钒液流电池因其易于规模化、环境友好和高安全性等优势，被视为一种适合大规模商业化应用的储能技术。然而，长期循环使用中出现的容量衰减问题限制了其在储能领域的广泛应用。本文通过深入分析电池循环前后的电化学特性变化曲线，并结合高锰酸钾滴定的结果，确定了电解液失衡和电极退化导致的负极活性物质减少和极化加剧是电池容量衰减的主要因素。此外，采用草酸还原的方法将电解液的放电比容量恢复至初始的92.7%，并通过互换正负电极缓解了电池的极化加剧，证实了通过电极交换可以有效恢复并稳定电极的电化学活性。最后，采用恒压充电的方法解决了草酸残留问题，并制定了一种草酸恢复电解液的工艺路线，成功将已用电解液的平均价态从3.580价恢复至3.508价。该研究全面分析了全钒液流电池容量衰减的深层次原因，为电解液的恢复发挥了重要的指导作用，同时针对草酸恢复过程中的残留问题提出了简便有效的技术解决方案，为电解液的恢复和再利用提供了新的可能性。

关键词: 全钒液流电池, 电解液恢复, 草酸还原, 化学滴定

Abstract:

Vanadium flow battery (VFB) is considered a promising energy storage technology for large-scale commercial application due to their easy scalability, environmental friendliness, and high safety. However, capacity fade during long-term cycling limits their widespread application in the energy storage field. This study deeply analyzed the changes in electrochemical characteristics of VFB before and after cycling, and combined with the results of potassium permanganate titration, identified electrolyte imbalance and electrode degradation leading to a reduction in anode active material and increased polarization as the main factors for capacity fade. Additionally, the specific discharge capacity of the electrolyte was restored to 92.7% of its initial capacity using oxalic acid reduction, and battery polarization was alleviated by swapping the anode and cathode, confirming that electrode exchange can effectively restore and stabilize the electrochemical activity of the electrodes. Finally, the oxalic acid residue issue was resolved using a constant-voltage charging method, and a process route for oxalic acid recovery of the electrolyte was established, successfully restoring the average oxidation state of the spent electrolyte from 3.580 to 3.508. This research comprehensively analyzed the underlying causes of VFB capacity fade, providing significant guidance for the recovery of the electrolyte. Meanwhile, it proposed a simple and effective technical solution for the residue issue during the oxalic acid recovery process, offering new possibilities for the recovery and reuse of the electrolyte.

Key words: vanadium flow battery, electrolyte recovery, oxalic acid reduction, chemical titration

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