Preparation and characterization of SPES/PVA (double-layer) membrane for vanadium redox flow battery

2018 ◽  
Vol 31 (2) ◽  
pp. 148-153 ◽  
Author(s):  
Jili Xie ◽  
Guanlin Li ◽  
Wang Tan

The double-layer membrane consisting of sulfonated poly(ether sulfone) (SPES) sub-layer and polyvinyl alcohol (PVA) sub-layer (denoted as SPES/PVA membrane) was prepared and employed as the separator for vanadium redox flow battery (VRB) system to evaluate the vanadium ions permeability and cell performance. The SPES/PVA membrane is a double-layer structure and exhibits dramatically lower vanadium ions permeability and better cell performance compared to the pristine SPES membrane, PVA membrane, and Nafion117 membrane. The vanadium ion permeability of SPES/PVA membrane is one order of magnitude lower than that of Nafion117 membrane. In further work, the single cell with SPES/PVA membrane showed significantly lower capacity loss, higher coulombic efficiency (>92.5%), and higher energy efficiency (>83.9%) than Nafion117 membrane. In the self-discharge test, SPES/PVA membrane showed 1.8 times longer duration in the open circuit decay than Nafion117 membrane. With all the good properties and low cost, this new kind of double-layer membrane is suggested to have excellent commercial prospects as an ion exchange membrane for VRB systems.

Batteries ◽  
2021 ◽  
Vol 7 (3) ◽  
pp. 53
Author(s):  
Purna C. Ghimire ◽  
Arjun Bhattarai ◽  
Tuti M. Lim ◽  
Nyunt Wai ◽  
Maria Skyllas-Kazacos ◽  
...  

Progress in renewable energy production has directed interest in advanced developments of energy storage systems. The all-vanadium redox flow battery (VRFB) is one of the attractive technologies for large scale energy storage due to its design versatility and scalability, longevity, good round-trip efficiencies, stable capacity and safety. Despite these advantages, the deployment of the vanadium battery has been limited due to vanadium and cell material costs, as well as supply issues. Improving stack power density can lower the cost per kW power output and therefore, intensive research and development is currently ongoing to improve cell performance by increasing electrode activity, reducing cell resistance, improving membrane selectivity and ionic conductivity, etc. In order to evaluate the cell performance arising from this intensive R&D, numerous physical, electrochemical and chemical techniques are employed, which are mostly carried out ex situ, particularly on cell characterizations. However, this approach is unable to provide in-depth insights into the changes within the cell during operation. Therefore, in situ diagnostic tools have been developed to acquire information relating to the design, operating parameters and cell materials during VRFB operation. This paper reviews in situ diagnostic tools used to realize an in-depth insight into the VRFBs. A systematic review of the previous research in the field is presented with the advantages and limitations of each technique being discussed, along with the recommendations to guide researchers to identify the most appropriate technique for specific investigations.


2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Qiang Li ◽  
Anyu Bai ◽  
Zeqiang Qu ◽  
Tianyu Zhang ◽  
Jie Li ◽  
...  

A comprehensive study on the hydroxyl multiwalled carbon nanotubes (hydroxyl MWCNTs) as catalysts in a positive reaction was performed to improve the efficiency of the vanadium redox flow battery (VRFB). The physicochemical properties of the hydroxyl MWCNT-modified electrode were characterized by using a scanning electron microscope (SEM), conductivity measurement, Brunner–Emmet–Teller (BET) measurement, X-ray photoelectron spectroscopy (XPS) analysis, cyclic voltammetry (CV) tests, electrochemical impedance spectroscopy (EIS) analysis, and charge-discharge tests. The prepared composite electrode possesses a huge amount of oxygen-containing groups, high-specific surface area, high electrical conductivity, and high catalytic activity towards the VO2+/VO2+ reaction based on physicochemical characterization. The hydroxyl MWCNT-modified graphite felt (hydroxyl MWCNTs/GF) shows the best cell performance with the energy efficiency of 79.74% and remains in high stability after 50 cycles. The improved cell performance is probably ascribed to the increase in active sites, fast charge transfer, and mass transfer rate of the introduced hydroxyl MWCNTs.


2019 ◽  
Vol 6 (1) ◽  
pp. 181309 ◽  
Author(s):  
Muqing Ding ◽  
Tao Liu ◽  
Yimin Zhang ◽  
Zhenlei Cai ◽  
Yadong Yang ◽  
...  

It is important to study the effect of Fe(III) on the positive electrolyte, in order to provide some practical guidance for the preparation and use of vanadium electrolyte. The effect of Fe(III) on the thermal stability and electrochemical behaviour of the positive electrolyte for the vanadium redox flow battery (VRFB) was investigated. When the Fe(III) concentration was above 0.0196 mol l −1 , the thermal stability of V(V) electrolyte was impaired, the diffusion coefficient of V(IV) species decreased from (2.06–3.33) × 10 −6 cm 2 s −1 to (1.78–2.88) × 10 −6 cm 2 s −1 , and the positive electrolyte exhibited a higher electrolyte resistance and a charge transfer resistance. Furthermore, Fe(III) could result in the side reaction and capacity fading, which would have a detrimental effect on battery application. With the increase of Fe(III), the collision probability of vanadium ions with Fe(III) and the competition with the redox reaction was aggravated, which would interfere with the electrode reaction, the diffusion of vanadium ions and the performance of VRFB. Therefore, this study provides some practical guidance that it is best to bring the impurity of Fe(III) below 0.0196 mol l −1 during the preparation and use of vanadium electrolyte.


Polymer ◽  
2018 ◽  
Vol 140 ◽  
pp. 233-239 ◽  
Author(s):  
Jicui Dai ◽  
Yichao Dong ◽  
Peng Gao ◽  
Jing Ren ◽  
Cong Yu ◽  
...  

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