Electrode degradation mechanisms in capacitive deionisation

Giurg, Adam; Denk, Karel; Bystroň, Tomáš; Paidar, Martin; Bouzek, Karel

doi:10.1016/j.desal.2020.114622

Cited by 10 publications

(11 citation statements)

References 42 publications

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“…The pH in the cathode region was alkaline, whereas that in the anode region was acidic. 73 SA shows better solubility under alkaline conditions than under acidic conditions, explaining the observed results. The SEM images of MT−AC and HT−AC electrodes showed a dense coating, which was not considerably damaged, and a surface morphology of the composite electrode that was unchanged from its original state.…”

Section: Table 2 Permselectivities Of Mt or Ht Coatingssupporting

confidence: 65%

“…This effect was more notable at the anode owing to the local pH difference in the CDI system. The pH in the cathode region was alkaline, whereas that in the anode region was acidic . SA shows better solubility under alkaline conditions than under acidic conditions, explaining the observed results.…”

Section: Resultsmentioning

confidence: 56%

“…Alternatively, the HT–MT-2 system could operate stably for 50 h, maintaining CE and SAC of 90.5% and 15.8 mg g –1 , respectively, at the 100th cycle. Oxygen reduction and carbon oxidation are two common Faradaic reactions occurring in CDI, which cause an increase and decrease in pH, respectively. , Figure shows that the HT–MT-2 system showed less pH fluctuation than the bare CDI system, indicating that Faradaic reactions were prevented in the HT–MT-2 system.…”

Section: Resultsmentioning

confidence: 98%

“…Oxygen reduction and carbon oxidation are two common Faradaic reactions occurring in CDI, which cause an increase and decrease in pH, respectively. 8,73 Figure 8 shows that the HT−MT-2 system showed less pH fluctuation than the bare CDI system, indicating that Faradaic reactions were prevented in the HT−MT-2 system.…”

Section: Table 2 Permselectivities Of Mt or Ht Coatingsmentioning

confidence: 99%

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Novel Inorganic Integrated Membrane Electrodes for Membrane Capacitive Deionization

Liang

et al. 2021

ACS Appl. Mater. Interfaces

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In capacitive deionization (CDI), coion repulsion and Faradaic reactions during charging reduce the charge efficiency (CE), thus limiting the salt adsorption capacity (SAC) and energy efficiency. To overcome these issues, membrane CDI (MCDI) based on the enhanced permselectivity of the anode and cathode is proposed using the ion-exchange polymer as the independent membrane or coating. To develop a novel and cost-effective MCDI system, we fabricated an integrated membrane electrode using a thin layer of the inorganic ion-exchange material coated on the activated carbon (AC) electrode, which effectively improves the ion selectivity. Montmorillonite (MT, Al2O9Si3) and hydrotalcite (HT, Mg6Al2(CO3)(OH)16·4H2O) were selected as the main active anion- and cation-exchange materials, respectively, for the cathode and anode. The HT–MT MCDI system employing HT–AC and MT–AC electrodes obtained a CE of 90.5% and an SAC of 15.8 mg g–1 after 100 consecutive cycles (50 h); these values were considerably higher than those of the traditional CDI system employing pristine AC electrodes (initially, a CE of 55% and an SAC of 10.2 mg g–1, which attenuated continuously to zero, and even “inverted work” occurs after 50 h, i.e., desorption during charging and adsorption during discharging). The HT–MT MCDI system showed moderate tolerance to organic matters during desalination and retained 84% SAC and 89% CE after 70 cycles in 50–200 mg L–1 sodium alginate. This study demonstrates a simple and cost-effective method for fabricating high-CE electrodes for desalination with great application potential.

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Section: Table 2 Permselectivities Of Mt or Ht Coatingssupporting

confidence: 65%

Section: Resultsmentioning

confidence: 56%

Section: Resultsmentioning

confidence: 98%

Section: Table 2 Permselectivities Of Mt or Ht Coatingsmentioning

confidence: 99%

See 2 more Smart Citations

Novel Inorganic Integrated Membrane Electrodes for Membrane Capacitive Deionization

Liang

et al. 2021

ACS Appl. Mater. Interfaces

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“…The smaller SAC and Λ indicated the possible occurrence of side reactions of co-intercalation of protons into the electrode, the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), which would consume a portion of the charge and therefore do not contribute to the removal of Na + from the solution. 14,50,51 As shown in studies on aqueous batteries, the use of neutral pH electrolytes generally show higher operating voltages than acidic or alkaline electrolytes, which is attributed to the larger HER and OER overpotentials in the neutral electrolytes. 52 The cycling efficiency for both electrodes under all three conditions was high (CE > 94%), indicating nearly identical duration time for charging and discharging cycles for each condition.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Metal-Ion Depletion Impacts the Stability and Performance of Battery Electrode Deionization over Multiple Cycles

Shi

Newcomer

Son

et al. 2021

Environ. Sci. Technol.

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Prussian blue hexacyanoferrate (HCF) materials, such as copper hexacyanoferrate (CuHCF) and nickel hexacyanoferrate (NiHCF), can produce higher salt removal capacities than purely capacitive materials when used as electrode materials during electrochemical water deionization due to cation intercalation into the HCF structure. One factor limiting the application of HCF materials is their decay in deionization performance over multiple cycles. By examining the performance of CuHCF and NiHCF electrodes at three different pH values (2.5, 6.3, and 10.2) in multiple-cycle deionization tests, losses in capacity (up to 73% for CuHCF and 39% for NiHCF) were shown to be tied to different redoxactive centers through analysis of dissolution of electrode metals. Both copper and iron functioned as active centers for Na + removal in CuHCF, while iron was mainly the active center in NiHCF. This interaction of Na + and active centers was demonstrated by correlating the decrease in performance to the concentration of these metal ions in the effluent solutions collected over multiple cycles at different pHs (up to 0.86 ± 0.14 mg/L for iron and 0.42 ± 0.17 mg/L for copper in CuHCF and 0.38 ± 0.05 mg/L for iron in NiHCF). Both materials were more stable (<11% decay for CuHCF and no decay for NiHCF) when the appropriate metal salt (copper or nickel) was added to the feed solutions to inhibit electrode dissolution. At a pH of 2.5, there was an increased competition between protons and Na + ions, which decreased the Na + removal amount and lowered the thermodynamic energy efficiency for deionization for both electrode materials. Therefore, while an acidic pH provided the most stable performance, a circumneutral pH would be useful to produce a better balance between performance and longevity.

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Development of Composite Nanostructured Electrodes for Water Desalination via Membrane Capacitive Deionization

Bakola,

Kotrotsiou,

Ntziouni

et al. 2024

Macromol. Rapid Commun.

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Novel two‐layer nanostructured electrodes were successfully prepared for their application in membrane capacitive deionization (MCDI) processes. Nanostructured carbonaceous materials such as graphene oxide (GO) and carbon nanotubes (CNTs), as well as activated carbon (AC) were dispersed in a solution of poly(vinyl alcohol) (PVA), mixed with polyacrylic acid (PAA) or polydimethyldiallylammonium chloride (PDMDAAC), and subsequently cast on the top surface of an activated carbon‐based modified graphite electrode to form a thin composite layer that was cross‐linked with glutaraldehyde (GA). Cyclic Voltammetry (CV) was performed to investigate the electrochemical properties of the composite electrodes and desalination experiments were conducted in batch mode using a MCDI unit cell to investigate the effects of i) the nanostructured carbonaceous material, ii) its concentration in the polymer blend, and iii) the molecular weight of the polymers on the desalination efficiency of the system. Comparative studies with commercial membranes were performed proving that the composite nanostructured electrodes were more efficient in salt removal. The improved performance of the composite electrodes was attributed to the ion exchange properties of the selected polymers and the increased specific capacitance of the nanostructured carbonaceous materials. This research paves the way for wider application of MCDI in water desalination.This article is protected by copyright. All rights reserved

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Electrode degradation mechanisms in capacitive deionisation

Cited by 10 publications

References 42 publications

Novel Inorganic Integrated Membrane Electrodes for Membrane Capacitive Deionization

Novel Inorganic Integrated Membrane Electrodes for Membrane Capacitive Deionization

Metal-Ion Depletion Impacts the Stability and Performance of Battery Electrode Deionization over Multiple Cycles

Development of Composite Nanostructured Electrodes for Water Desalination via Membrane Capacitive Deionization

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