Corrosion prevention of graphite collector in vanadium redox flow battery

Rudolph, Stephen A.; Schröder, Uwe; Bayanov, I. M.; Pfeiffer, G.

doi:10.1016/j.jelechem.2013.09.033

Cited by 33 publications

(28 citation statements)

References 15 publications

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“…4 . In this work both half-cell electrolytes were prepared in different SOCs in a conventional VRF cell setup at 40 mA/cm 2 using a potentiostat/galvanostat (Solartron Analytical Modulab Pstat potentiostat/galvanostat, UK).…”

Section: Methodsmentioning

confidence: 99%

Chemical Stability of Graphite-Polypropylene Bipolar Plates for the Vanadium Redox Flow Battery at Resting State

Satola

Kirchner

Komsiyska

et al. 2016

J. Electrochem. Soc.

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Current collectors called bipolar plates (BPP) are important elements within the conversion unit of the vanadium redox flow battery (VRFB). They are in direct contact with acidic electrolytes, containing vanadium species in different oxidation states. The influence of the state of charge (SOC) on the calendar aging of BPPs was examined. Graphite-polypropylene BPPs were immersed in positive and negative vanadium electrolytes at 0%, 20%, 80% and 100% SOC for 30, 90 and 190 days. H 2 gas evolution was observed as side reaction on the surface of the BPPs in the negative electrolyte. After electroless aging, scanning electron (SEM) and confocal microscopy measurements showed no significant changes in the surface morphology. The electrical conductivities of the BPPs were not affected significantly. However, contact angle (θ) measurements revealed that the positive electrolyte influenced the wettability of the BPPs. X-ray photoelectron (XP) spectroscopy showed progressing oxidation of the BPP surfaces in the positive electrolyte and adsorption or entrapment of vanadium ions in the pores at high SOC. Cyclic voltammograms (CV) provided evidence that the graphite was oxidized combined with an increase in effective surface area. ATR-FTIR measurements showed slight oxidation of pure polypropylene granulate in the positive electrolyte with 100% SOC. The increasing energy power supply from intermittent renewable energy sources requires a rapid introduction of efficient energy storages. One promising technology is the vanadium redox flow battery (VRFB), as it enables to scale the power and the storage capacity independently according to specific requirements.1,2 In addition the VRFB is characterized by a fast response time and long electrolyte cycle life.3 Each reaction unit in a VRFB stack is composed of two half-cells separated by a membrane consisting of an electrode in contact with a current collector called bipolar plate (BPP).2 In a battery stack the BPPs are "non-active" components that conduct current from one cell to the other. They physically separate adjacent cells from each other while staying in contact with acidic half-cell electrolytes containing vanadium species in different oxidation states on each side. 4 For brevity we call the V 2+ /V 3+ solution "negative electrolyte" and the VO 2+ /VO 2 + solution "positive electrolyte". While vanadium redox reactions mainly occur on the surfaces of the porous electrodes, they could also occur unintentionally on the surfaces of the BPPs. [5][6][7] Therefore, a good BPP should be characterized by a high chemical and mechanical stability, high electrical conductivity and impermeability to preclude leakage. 8 Metallic BPPs are usually not used in VRFB as they corrode in acidic environments and would need a protective layer.5,9,10 Therefore, graphite based BPPs are commonly used as they possess a good electrical conductivity and a better chemical stability. 4 However, pure graphite plates are not favored as BPPs due to their high weight and cost as well as low mechanical stre...

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Section: Methodsmentioning

confidence: 99%

Chemical Stability of Graphite-Polypropylene Bipolar Plates for the Vanadium Redox Flow Battery at Resting State

Satola

Kirchner

Komsiyska

et al. 2016

J. Electrochem. Soc.

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“…Actually, minor attention has been paid to develop a novel alternative current collector with powerful tolerance toward corrosion in LiTFSI systems. Usually, graphite materials are used as current collectors in fuel cells and vanadium redox flow batteries, because of their good electrical conductivity and excellent corrosion resistance [15]. However, the above-mentioned graphite materials lack enough flexibility and electrochemical stability.…”

Section: Introductionmentioning

confidence: 99%

Anticorrosive flexible pyrolytic polyimide graphite film as a cathode current collector in lithium bis(trifluoromethane sulfonyl) imide electrolyte

Han

Zhang

Huang

et al. 2014

Electrochemistry Communications

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a b s t r a c t a r t i c l e i n f oFlexible pyrolytic polyimide graphite film (PGF) is explored as a cathode current collector in lithium ion batteries using lithium bis(trifluoromethane sulfonyl) imide (LiTFSI) based electrolyte. It is demonstrated that no obvious anodic current is observed up to 4.5 V versus Li + /Li for PGF, while significant corrosion current is found from 3.6 V for aluminum, indicative of better electrochemical stability of PGF than that of aluminum in LiTFSI based electrolyte. LiMn 2 O 4 on aluminum and PGF has been used as model electrode for testing. There is hardly any capacity retained after 10 cycles at room temperature for the LiMn 2 O 4 /aluminum electrode. With regard to the LiMn 2 O 4 /PGF electrode, the capacity retention ratio remained 89% after 1000 cycles. Moreover, at an elevated temperature of 55°C, the capacity retention ratio kept at 81% after 300 cycles. Since LiTFSI-based electrolyte shows advantages in safety, stability and conductivity but could not be used due to Al-corrosion, the application of the PGF current collector could overcome this barrier.

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“…6,7 The composites usually contain conductive carbon components such as graphite, carbon black, carbon fibers or nanotubes and a polymeric binder such as polyethylene, polypropylene, epoxy resin or fluoropolymers. 5,[8][9][10][11] In general it is reported that the electrolyte of the VRFB has a long cycle life as well as a good recyclability. 3,4 However, components of the battery stack suffer irreversible damages upon aging due to the acidic media and harsh oxidative conditions.…”

mentioning

confidence: 99%

Bulk Aging of Graphite-Polypropylene Current Collectors Induced by Electrochemical Cycling in the Positive Electrolyte of Vanadium Redox Flow Batteries

Satola

Komsiyska

Wittstock

2017

J. Electrochem. Soc.

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Carbon-based bipolar plates (BPP) are essential components of the vanadium redox flow battery (VRFB) stack guaranteeing electrical conductivity and physical separation of adjacent cells. They are usually made of composite materials with complex structures containing conductive carbon components and polymer binder materials. In order to investigate their aging by simulation of repetitive charging/discharging conditions in areas with sluggish electrolyte flow, commercially available graphite-polypropylene BPPs were subjected to galvanodynamic treatment under diffusion limitation conditions in a three electrode electrochemical cell with positive electrolyte (VO2+/VO2+) using different states of charge (SOC). The current was swept between 100 and −100 mA/cm2. After aging, cyclic voltammetry (CV) in diluted H2SO4 was used to analyze the change in double layer capacitance and redox activity of the BPPs. Morphological investigations of the surface texture and bulk material were performed by means of scanning electron and confocal microscopies as well as by X-ray computed microtomography. After 3000 sweeping cycles in the positive electrolyte at high SOC the BPP showed an increase in double layer capacitance as well as higher roughness and increase in open pore volume in depths up to 100 μm. The aging effects are ascribed to oxidation and corrosion of the surface.

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Corrosion prevention of graphite collector in vanadium redox flow battery

Cited by 33 publications

References 15 publications

Chemical Stability of Graphite-Polypropylene Bipolar Plates for the Vanadium Redox Flow Battery at Resting State

Chemical Stability of Graphite-Polypropylene Bipolar Plates for the Vanadium Redox Flow Battery at Resting State

Anticorrosive flexible pyrolytic polyimide graphite film as a cathode current collector in lithium bis(trifluoromethane sulfonyl) imide electrolyte

Bulk Aging of Graphite-Polypropylene Current Collectors Induced by Electrochemical Cycling in the Positive Electrolyte of Vanadium Redox Flow Batteries

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