The Development of Zn–Ce Hybrid Redox Flow Batteries for Energy Storage and Their Continuing Challenges

Anodic oxidation of cerous ions and cathodic reduction of ceric ions, in aqueous acidic solutions, play an important role in electrochemical processes at laboratory and industrial scale. Ceric ions, which have been used for oxidation of organic wastes and off-gases in environmental treatment, are a wellestablished oxidant for indirect organic synthesis and specialised cleaning processes, including oxide film removal from tanks and process pipework in nuclear decontamination. They also provide a classical reagent for chemical analysis in the laboratory. The reversible oxidation of cerous ions is an important reaction in the positive compartment of various redox flow batteries during charge and discharge cycling. A knowledge of the thermodynamics and kinetics of the redox reaction is critical to an understanding of the role of cerium redox species in these applications. Suitable choices of electrode material (metal or ceramic; coated or uncoated), geometry/structure (2-or 3-dimensional) and electrolyte flow conditions (hence an acceptable mass transport rate) are critical to achieving effective electrocatalysis, a high performance and a long lifetime. This review considers the electrochemistry of soluble cerium species and their diverse uses in electrochemical technology, especially for redox flow batteries and mediated electrochemical oxidation.

Section: Redox Flow Batteriesmentioning

confidence: 99%

Electrochemical redox processes involving soluble cerium species

Arenas

León

Walsh

2016

“…The zinc-cerium redox flow battery (Zn-Ce RFB) has been the subject of semicontinuous development over the past decade; its progress and research challenges have been recently reviewed [1,2]. Its main advantages are a higher standard cell potential (2.48 V) and lower electrolyte toxicity than all-vanadium or Zn-Br 2 RFBs.…”

Section: Introductionmentioning

confidence: 99%

“…Platinised titanium (Pt/Ti) is a suitable electrode material for this reaction due to its catalytic activity for cerium conversion together with its stability to highly oxidising Ce(IV) ions [1].…”

Section: Introductionmentioning

confidence: 99%

“…The positive electrode also supports the oxygen evolution reaction (OER) as a secondary reaction during anodic Ce(III) oxidation: This results in a lower current efficiency for reaction (1), especially at high current densities on planar electrodes or under low mass transport conditions. Porous, 3-D electrodes can reduce these limitations by decreasing the local current density and increasing the mass transport rate of Ce(IV) ions to the electrode surface.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Mass transport and active area of porous Pt/Ti electrodes for the Zn-Ce redox flow battery determined from limiting current measurements

Arenas

León

Walsh

2016

Self Cite

The conversion of soluble cerium redox species in the zinc-cerium redox flow battery and other electrochemical processes can be carried out at planar and porous platinised titanium electrodes.The active area, current density, mass transfer coefficient and linear electrolyte flow velocity through these structures have a direct influence on the reaction yield and the relationship between cell potential and operational current density during charge and discharge of a flow battery. A quantitative and practical characterization of the reaction environment at these electrodes is required. The volumetric mass transfer coefficient, " $ has been calculated from limiting current measurements for Ce(IV) ion reduction in a laboratory, rectangular channel flow cell. This factor can be used to predict fractional conversion and required electrode dimensions. Highly porous platinised titanium felt shows superior " $ values and is wellsuited as a high performance electrode material.

“…The charge and energy efficiencies were 82 % and 72 % respectively, for a current density of 20 mA cm -2 . A detailed and up to date review on the latest developments on the zinc-cerium flow cell has been provided by Walsh et al [37].…”

Section: Page 3 Of 25mentioning

confidence: 99%

Factors affecting the performance of the Zn-Ce redox flow battery

Nikiforidis

Cartwright

Hodgson

et al. 2014

Self Cite

This version is available at https://strathprints.strath.ac.uk/50808/ Strathprints is designed to allow users to access the research output of the University of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (https://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge.Any correspondence concerning this service should be sent to the Strathprints administrator: strathprints@strath.ac.ukThe Strathprints institutional repository (https://strathprints.strath.ac.uk) is a digital archive of University of Strathclyde research outputs. It has been developed to disseminate open access research outputs, expose data about those outputs, and enable the management and persistent access to Strathclyde's intellectual output. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. AbstractThe Hull Cell was used to investigate the impact of current density j on the morphology and uniformity of zinc electrodeposited from a 2.5 mol dm −3 Zn 2+ solution in 1.5 mol dmmethanesulfonic acid at 40°C onto carbon-composite surfaces. The range of the applied deposition current density used was between 1 mA cm −2 and 100 mA cm −2 . Good, robust deposits were obtained when j ≥ 10 mA cm _2 whereas at j's lower than this, patchy films formed due to the competing hydrogen evolution reaction (HER) on the bare carboncomposite surface. An understanding of these effects and its application in the redox flow battery enabled both the coulombic and cell potential efficiencies to be maintained at relatively high values, 90% and 69% respectively, indicating a successful inhibition of the HER on the fully formed Zn layer. Flow velocity at the low Reynolds number in the cell (Re <200) had little impact on the electrochemical cell performance. Depletion of the cerium species became an issue for long charge times.