Laboratory XANES to study vanadium species in vanadium redox flow batteries

2020 ◽  
Vol 35 (S1) ◽  
pp. S24-S28 ◽  
Author(s):  
Christian Lutz ◽  
Ursula Elisabeth Adriane Fittschen

The speciation of vanadium in the electrolyte of vanadium redox flow batteries (VRFBs) is important to determine the state of charge of the battery. To obtain a better understanding of the transport of the different vanadium species through the separator polymer electrolyte membranes, it is necessary to be able to determine concentration and species of the vanadium ions inside the nanoscopic water body of the membranes. The speciation of V in the electrolyte of VRFBs has been performed by others at the synchrotron by X-ray absorption near-edge structure analysis (XANES). However, the concentrations are quite high and not necessarily justify the use of a large-scale facility. Here, we show that vanadium species in the electrolyte and inside the ionomeric membranes can be determined by laboratory XANES. We were able to determine V species in the 1.6 M electrolyte with a measurement time of 2.3 h and V species having a concentration of 9.8 g kg−1 inside the membranes (178 µm thick) with a measurement time of 5 h. Our results show that laboratory XANES is an appropriate tool to study these kind of samples.

2021 ◽  
Vol 85 ◽  
pp. 100926
Author(s):  
Xingyi Shi ◽  
Oladapo Christopher Esan ◽  
Xiaoyu Huo ◽  
Yining Ma ◽  
Zhefei Pan ◽  
...  

Energies ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 176
Author(s):  
Iñigo Aramendia ◽  
Unai Fernandez-Gamiz ◽  
Adrian Martinez-San-Vicente ◽  
Ekaitz Zulueta ◽  
Jose Manuel Lopez-Guede

Large-scale energy storage systems (ESS) are nowadays growing in popularity due to the increase in the energy production by renewable energy sources, which in general have a random intermittent nature. Currently, several redox flow batteries have been presented as an alternative of the classical ESS; the scalability, design flexibility and long life cycle of the vanadium redox flow battery (VRFB) have made it to stand out. In a VRFB cell, which consists of two electrodes and an ion exchange membrane, the electrolyte flows through the electrodes where the electrochemical reactions take place. Computational Fluid Dynamics (CFD) simulations are a very powerful tool to develop feasible numerical models to enhance the performance and lifetime of VRFBs. This review aims to present and discuss the numerical models developed in this field and, particularly, to analyze different types of flow fields and patterns that can be found in the literature. The numerical studies presented in this review are a helpful tool to evaluate several key parameters important to optimize the energy systems based on redox flow technologies.


2014 ◽  
Vol 86 (5) ◽  
pp. 633-649 ◽  
Author(s):  
Xiongwei Wu ◽  
Junping Hu ◽  
Jun Liu ◽  
Qingming Zhou ◽  
Wenxin Zhou ◽  
...  

Abstract In recent years, much attention has been paid to vanadium redox flow batteries (VRBs) because of their excellent performance as a new and efficient energy storage system, especially for large-scale energy storage. As one core component of a VRB, ion exchange membrane prevents cross-over of positive and negative electrolytes, while it enables the transportation of charge-balancing ions such as H+, $${\text{SO}}_4^{2 - },$$ and $${\text{HSO}}_4^ - $$ to complete the current circuit. To a large extent, its structure and property affect the performance of VRBs. This review focuses on the latest work on the ion exchange membranes for VRBs such as perfluorinated, partially fluorinated, and nonfluorinated membranes. The prospective for future development on membranes for VRBs is also proposed.


Membranes ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 244
Author(s):  
Byungchan Bae ◽  
Dukjoon Kim

Recently, polymer electrolyte membranes have been used in various electrochemical energy devices and other applications, such as fuel cells, lithium secondary batteries, redox flow batteries, electrodialysis, and membrane capacitive deionization [...]


Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 926
Author(s):  
Nana Zhao ◽  
Harry Riley ◽  
Chaojie Song ◽  
Zhengming Jiang ◽  
Keh-Chyun Tsay ◽  
...  

Polymer membranes play a vital role in vanadium redox flow batteries (VRFBs), acting as a separator between the two compartments, an electronic insulator for maintaining electrical neutrality of the cell, and an ionic conductor for allowing the transport of ionic charge carriers. It is a major influencer of VRFB performance, but also identified as one of the major factors limiting the large-scale implementation of VRFB technology in energy storage applications due to its cost and durability. In this work, five (5) high-priority characteristics of membranes related to VRFB performance were selected as major considerable factors for membrane screening before in-situ testing. Eight (8) state-of-the-art of commercially available ion exchange membranes (IEMs) were specifically selected, evaluated and compared by a set of ex-situ assessment approaches to determine the possibility of the membranes applied for VRFB. The results recommend perfluorosulfonic acid (PFSA) membranes and hydrocarbon anion exchange membranes (AEMs) as the candidates for further in-situ testing, while one hydrocarbon cation exchange membrane (CEM) is not recommended for VRFB application due to its relatively high VO2+ ion crossover and low mechanical stability during/after the chemical stability test. This work could provide VRFB researchers and industry a valuable reference for selecting the polymer membrane materials before VRFB in-situ testing.


Membranes ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 576
Author(s):  
Christian Lutz ◽  
Michael Breuckmann ◽  
Sven Hampel ◽  
Martin Kreyenschmidt ◽  
Xi Ke ◽  
...  

A core component of energy storage systems like vanadium redox flow batteries (VRFB) is the polymer electrolyte membrane (PEM). In this work, the frequently used perfluorosulfonic-acid (PFSA) membrane Nafion™ 117 and a novel poly (vinylidene difluoride) (PVDF)-based membrane are investigated. A well-known problem in VRFBs is the vanadium permeation through the membrane. The consequence of this so-called vanadium crossover is a severe loss of capacity. For a better understanding of vanadium transport in membranes, the uptake of vanadium ions from electrolytes containing Vdimer(IV–V) and for comparison also V(II), V(III), V(IV), and V(V) by both membranes was studied. UV/VIS spectroscopy, X-ray absorption near edge structure spectroscopy (XANES), total reflection X-ray fluorescence spectroscopy (TXRF), inductively coupled plasma optical emission spectrometry (ICP-OES), and micro X-ray fluorescence spectroscopy (microXRF) were used to determine the vanadium concentrations and the species inside the membrane. The results strongly support that Vdimer(IV–V), a dimer formed from V(IV) and V(V), enters the nanoscopic water-body of Nafion™ 117 as such. This is interesting, because as of now, only the individual ions V(IV) and V(V) were considered to be transported through the membrane. Additionally, it was found that the Vdimer(IV–V) dimer partly dissociates to the individual ions in the novel PVDF-based membrane. The Vdimer(IV–V) dimer concentration in Nafion™ was determined and compared to those of the other species. After three days of equilibration time, the concentration of the dimer is the lowest compared to the monomeric vanadium species. The concentration of vanadium in terms of the relative uptake λ = n(V)/n(SO3) are as follows: V(II) [λ = 0.155] > V(III) [λ = 0.137] > V(IV) [λ = 0.124] > V(V) [λ = 0.053] > Vdimer(IV–V) [λ = 0.039]. The results show that the Vdimer(IV–V) dimer needs to be considered in addition to the other monomeric species to properly describe the transport of vanadium through Nafion™ in VRFBs.


2014 ◽  
Vol 86 (5) ◽  
pp. 661-669 ◽  
Author(s):  
Xiongwei Wu ◽  
Jun Liu ◽  
Xiaojuan Xiang ◽  
Jie Zhang ◽  
Junping Hu ◽  
...  

AbstractVanadium redox flow batteries (VRBs) are one of the most practical candidates for large-scale energy storage. Its electrolyte as one key component can intensively influence its electrochemical performance. Recently, much significant research has been carried out to improve the properties of the electrolytes. In this review, we present the optimization on vanadium electrolytes with sulfuric acid as a supporting electrolyte and their effects on the electrochemical performance of VRBs. In addition, other kinds of supporting electrolytes for VRBs are also discussed. Prospective for future development is also proposed.


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