当前位置: X-MOL 学术Electrochim. Acta › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
A correlated multi-observable assessment for vanadium redox flow battery state of charge estimation – Long-term stability of methods
Electrochimica Acta ( IF 5.5 ) Pub Date : 2025-01-20 , DOI: 10.1016/j.electacta.2025.145707
Niklas Janshen, Antonio Chica, Thorsten Struckmann

Accurate half cell specific state of charge (SOC) monitoring is needed for vanadium redox flow batteries (VRFB) to quantify electrolyte imbalances and to increase operation efficiency by appropriately timed re-balancing. However, electrolyte crossover shifts the vanadium concentrations and can impact the SOC estimation in combination with side reactions in the long run. As a result, the long-term stability of any SOC estimation is crucial for its accuracy, while a rigorous cross-evaluation of SOC monitoring methods for VRFBs is still missing in the literature. In this study, we investigate the long-term stability for SOC monitoring based on half cell electrolyte potentials, electrolyte densities, electrolyte volumes, electrolyte viscosity related pressure drops, pH related potentials and UV/Vis absorbances. We conduct 500 h long-term charge/discharge cycling for a membrane with 100 µm thickness and 300 h for a 50 µm thin membrane. For each cycle, we determine reference SOCs validated by potentiometric titration, which enables us to calculate calibration parameter for each SOC estimation method in each cycle. We analyze the variation and stability of these parameters and assess the long-term accuracy of each method. The highest long-term stability is shown by the UV/Vis absorbance measured at 400 nm in the negative half cell with estimation errors below 2 % and the electrolyte half cell potentials with errors below 2.5 %. The UV/Vis absorbance measured at 580 nm in the positive half cell exhibits a moderate stability with estimation errors lower than 5 %. The electrolyte densities and pressure drops measured in the negative half cell show moderate stabilities with estimation errors below 7.5 % which could allow for accurate SOC estimation with more frequent re-calibrations.

中文翻译:


钒氧化还原液流电池荷电状态估计的相关多可观察评估 - 方法的长期稳定性



钒氧化还原液流电池 (VRFB) 需要精确的半电池特定荷电状态 (SOC) 监测,以量化电解质失衡,并通过适当定时的重新平衡来提高运行效率。然而,电解质交叉会改变钒浓度,从长远来看,会与副反应一起影响 SOC 估计。因此,任何 SOC 估计的长期稳定性对其准确性都至关重要,而文献中仍然缺乏对 VRFB 的 SOC 监测方法的严格交叉评估。在这项研究中,我们研究了基于半电池电解质电位、电解质密度、电解质体积、电解质粘度相关压降、pH 相关电位和 UV/Vis 吸光度的 SOC 监测的长期稳定性。我们对 100μm 厚度的膜进行 500 小时的长期充放电循环,对 50μm 的薄膜进行 300 小时的长期充放电循环。对于每个周期,我们确定通过电位滴定验证的参考 SOC,这使我们能够计算每个周期中每种 SOC 估计方法的校准参数。我们分析这些参数的变化和稳定性,并评估每种方法的长期准确性。在负极半电池中 400nm 处测得的 UV/Vis 吸光度(估计误差低于 2%)和电解质半电池电位(误差低于 2.5%)显示出最高的长期稳定性。在正半电池中 580nm 处测得的 UV/Vis 吸光度表现出中等稳定性,估计误差低于 5%。在负极半电池中测得的电解质密度和压降显示出中等稳定性,估计误差低于 7.5%,这可以通过更频繁的重新校准实现准确的 SOC 估计。
更新日期:2025-01-20
down
wechat
bug