Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352 (USA).
ChemSusChem. 2014 Feb;7(2):577-84. doi: 10.1002/cssc.201300706. Epub 2013 Oct 29.
The results of the investigation of the capacity decay mechanism of vanadium redox flow batteries with microporous separators as membranes are reported. The investigation focuses on the relationship between the electrochemical performance and electrolyte compositions at both the positive and negative half-cells. Although the concentration of total vanadium ions remains nearly constant at both sides over cycling, the net transfer of solution from one side to the other and thus the asymmetrical valance of vanadium ions caused by the subsequent disproportionate self-discharge reactions at both sides lead to capacity fading. Through in situ monitoring of the hydraulic pressure of the electrolyte during cycling at both sides, the convection was found to arise from differential hydraulic pressures at both sides of the separators and plays a dominant role in capacity decay. A capacity-stabilizing method is developed and was successfully demonstrated through the regulation of gas pressures in both electrolyte tanks.
报告了微孔隔板作为膜的钒氧化还原流电池容量衰减机制的研究结果。该研究集中于正、负半电池中电解质组成与电化学性能之间的关系。尽管在循环过程中两侧的总钒离子浓度基本保持不变，但由于随后在两侧发生的自放电反应导致溶液从一侧向另一侧的净转移以及钒离子的价态不对称，从而导致容量衰减。通过在两侧循环过程中对电解质液压的原位监测，发现对流是由隔板两侧的压差引起的，并在容量衰减中起主导作用。开发了一种容量稳定化方法，并通过调节两个电解质罐中的气压成功地进行了验证。
