Effect of Compression Ratio of Graphite Felts on the Performance of an All-Vanadium Redox Flow Battery

Hsieh, Chin-Lung; Tsai, Po-Hong; Hsu, Ning-Yih; Chen, Yong-Song

doi:10.3390/en12020313

Cited by 19 publications

(13 citation statements)

References 27 publications

(31 reference statements)

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“…Consequently, carbon is the ideal material for use as a VRFB electrode. Graphite felt (GF) is the most widely used electrode material for VRFBs because of the three-dimensional network structure, large surface area, and high electrical conductivity of GF [8][9][10][11]. However, the poor electrochemical activity and hydrophobic properties of GF electrodes result in low kineticism in the redox reaction.…”

Section: Introductionmentioning

confidence: 99%

V2O5-Activated Graphite Felt with Enhanced Activity for Vanadium Redox Flow Battery

Wang

Hung

2021

Catalysts

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In this study, a simple and environment-friendly method of preparing activated graphite felt (GF) for a vanadium redox flow battery (VRFB) by depositing the vanadium precursor on the GF surface and calcining vanadium oxide was explored. The intermediate material, VO2, generated carbon oxidation during the calcination. In contrast to the normal etching method, this method was simple and without a pickling process. On the surface of the activated GF, multiple pores and increased roughness were noted after the calcination temperature and surface area of the activated GF reached 350 °C to 400 °C and 17.11 m2/g, respectively. Additionally, the polarization of the activated GF decreased with resistance to the charge transfer at 0.27 Ω. After a single-cell test at current density of 150 mA/cm2 was performed, the capacity utilization and the capacity retention after 50 cycles reached 70% and 84%, respectively. These results indicated the potential use of activated GF as an VRFB electrode.

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Section: Introductionmentioning

confidence: 99%

V2O5-Activated Graphite Felt with Enhanced Activity for Vanadium Redox Flow Battery

Wang

Hung

2021

Catalysts

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“…The in situ monitoring of the impedances of VRFBs has been performed to obtain information about changes in polarization resistance associated with electrode modification, degradation of materials, and optimization of the operating parameters, etc. [118][119][120][121][122][123][124][125][126][127][128]. The measurement of full cell impedance is performed by connecting the terminals of the signal analyzer to the terminals of the cell.…”

Section: Electrochemical Impedance Spectroscopy (Eis)mentioning

confidence: 99%

In-Situ Tools Used in Vanadium Redox Flow Battery Research—Review

Ghimire¹,

Bhattarai²,

Lim

et al. 2021

Batteries

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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.

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“…Subsequent experimental testing on laboratory-scale cells demonstrated improved energy efficiencies with wedge shaped cells, and a toroidal stack concept based on this concept was presented at the International Flow Battery Forum [18]. The effect of felt compression has been well documented [19,20] and other studies have applied the same theory in different ways, such as by modifying the materials instead of the cell geometry [21][22][23]. Another group has modified the cell architecture with asymmetric compression to address species crossover and associated capacity decay [24].…”

Section: Appl Sci 2020 10 X For Peer Reviewmentioning

confidence: 99%

Mass Transport Optimization for Redox Flow Battery Design

et al. 2020

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The world is moving to the next phase of the energy transition with high penetrations of renewable energy. Flexible and scalable redox flow battery (RFB) technology is expected to play an important role in ensuring electricity network security and reliability. Innovations continue to enhance their value by reducing parasitic losses and maximizing available energy over broader operating conditions. Simulations of vanadium redox flow battery (VRB/VRFB) cells were conducted using a validated COMSOL Multiphysics model. Cell designs are developed to reduce losses from pump energy while improving the delivery of active species where required. The combination of wedge-shaped cells with static mixers is found to improve performance by reducing differential pressure and concentration overpotential. Higher electrode compression at the outlet optimises material properties through the cell, while the mixer mitigates concentration gradients across the cell. Simulations show a 12% lower pressure drop across the cell and a 2% lower charge voltage for improved energy efficiency. Wedge-shaped cells are shown to offer extended capacity during cycling. The prototype mixers are fabricated using additive manufacturing for further studies. Toroidal battery designs incorporating these innovations at the kW scale are developed through inter-disciplinary collaboration and rendered using computer aided design (CAD).

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Effect of Compression Ratio of Graphite Felts on the Performance of an All-Vanadium Redox Flow Battery

Cited by 19 publications

References 27 publications

V2O5-Activated Graphite Felt with Enhanced Activity for Vanadium Redox Flow Battery

V2O5-Activated Graphite Felt with Enhanced Activity for Vanadium Redox Flow Battery

In-Situ Tools Used in Vanadium Redox Flow Battery Research—Review

Mass Transport Optimization for Redox Flow Battery Design

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