Enhancing capacitive deionization performance with charged structural polysaccharide electrode binders

Kim, Martin; Cerro, Martina del; Hand, Steven; Cusick, Roland D.

doi:10.1016/j.watres.2018.10.044

Cited by 31 publications

(22 citation statements)

References 41 publications

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“…However, improvements in η CE were significantly lower than previously reported values for electrodes with distributed fixed charge (e.g. charged carbon, charged binder, and polyelectrolyte coating) that were operated under constant voltage (Gao et al., 2015; 2016; M. Kim et al., 2019b) due to flow efficiency losses commonly associated with constant current operation of CDI cells (Hawks et al., 2018).…”

Section: Resultsmentioning

confidence: 61%

“…Ion-exchange membranes can be used to create a selective charge barrier to block co-ion transport and thereby improve the charge efficiency (Biesheuvel and van der Wal, 2010; Lee et al., 2006; Li et al., 2008), but membrane cost is potentially prohibitive (Biesheuvel and van der Wal, 2010). Alternatively, electrodes can be coated with charged polyelectrolytes or fabricated with charged binders to cover macropores ion-selective layer of low resistance to retain co-ions (Ahualli et al., 2017; Kim et al., 2019b). While polyelectrolyte coating could serve as a cost-effective means promoting counter ion flux into and out of electric double layers, it remains unclear if selectivity enhancements observed under constant voltage charging would hold under constant current operation, in which charge efficiency is limited by salt residue from preceding discharge strokes (Hawks et al., 2018; Shang et al., 2017).…”

Section: Introductionmentioning

confidence: 99%

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Reducing impedance to ionic flux in capacitive deionization with Bi-tortuous activated carbon electrodes coated with asymmetrically charged polyelectrolytes

et al. 2019

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Capacitive deionization (CDI) with electric double layers is an electrochemical desalination technology in which porous carbon electrodes are polarized to reversibly store ions. Planar composite CDI electrodes exhibit poor energetic performance due the resistance associated with salt depletion and tortuous diffusion in the macroporous structure. In this work, we investigate the impact of bi-tortuosity on desalination performance by etching macroporous patterns along the length of activated carbon porous electrodes in a flow-by CDI architecture. Capacitive electrodes were also coated with thin asymmetrically charged polyelectrolytes to improve ion-selectivity while maintaining the bitortuous macroporous channels. Under constant current operation, the equivalent circuit resistance in CDI cells operating with bi-tortuous electrodes was approximately 2.2 times less than a control cell with unpatterned electrodes, leading to significant increases in working capacitance (20–22 to 26.7–27.8 F g −1 ), round-trip efficiency (52–71 to 71–80%), and charge efficiency (33–59 to 35–67%). Improvements in these key performance indicators also translated to enhanced salt adsorption capacity, rate, and most importantly, the thermodynamic efficiency of salt separation (1.0–2.0 to 2.2–4.1%). These findings demonstrate that the use of bi-tortuous electrodes is a novel approach of reducing impedance to ionic flux in CDI.

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Section: Resultsmentioning

confidence: 61%

Section: Introductionmentioning

confidence: 99%

Reducing impedance to ionic flux in capacitive deionization with Bi-tortuous activated carbon electrodes coated with asymmetrically charged polyelectrolytes

et al. 2019

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“…In general, CDI systems are comprised of two identical activated carbon (AC) electrodes for capturing large numbers of ions . However, AC‐based CDI suffers from poor long‐term stabilities of the electrodes, mainly due to inevitable surface corrosion of ACs during operation .…”

Section: Introductionmentioning

confidence: 99%

Rapid Inversion of Surface Charges in Heteroatom‐Doped Porous Carbon: A Route to Robust Electrochemical Desalination

Kang

Kim

Chung

et al. 2019

Adv Funct Materials

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Given that a considerably large population suffers from shortage of water, there are numerous on‐going efforts to turn seawater into freshwater, and electrochemical desalination processes—particularly capacitive deionization (CDI)—have gained significant attention due to their high energy efficiency and reliable performance. Meanwhile, carbonaceous electrode materials, which are most commonly used in CDI systems, have poor long‐term stability due to unfavorable interactions with oxygen in saline water. Herein, rapid and vigorous inversion of surface charges in heteroatom‐doped carbon electrodes, which leads to a robust operation of CDI with high desalination capacity, is reported for the first time. By carbonization of coffee wastes, nitrogen‐ and sulfur‐codoped activated carbon with hierarchical micro/mesopores are prepared in an environmentally‐friendly manner, and this carbon results in a significantly higher inverted capacity than that of various activated carbon counterparts in long‐term CDI operations, without any sign of drop in performance. Investigations on the changes in physicochemical properties of the electrodes during the inversion disclose the favorable roles of nitrogen and sulfur dopants, which can be summarized as enlarging the difference between the surface charges of the two electrodes by chemical interactions with oxygen in the anode and carbon in the cathode.

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“…The increase in surface area, channel structure, and oxygen functional groups of CSG electrode enhanced the ion adsorption capacity. Kim, Cerro, Cerro, del Hand, and Cusick (2019) reported the synthesis of a new CDI electrode by incorporation of ionically charged structural polysaccharide and carboxymethyl cellulose as binder. The charged electrode binders enhanced rapid uptake of salts within macropores and the release of ions to uncovered pores of electrodes.…”

Section: Electro-sorption (Capacitive Deionization Cdi)mentioning

confidence: 99%

Hazardous wastes treatment technologies

Shih

et al. 2020

Water Environment Research

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Enhancing capacitive deionization performance with charged structural polysaccharide electrode binders

Cited by 31 publications

References 41 publications

Reducing impedance to ionic flux in capacitive deionization with Bi-tortuous activated carbon electrodes coated with asymmetrically charged polyelectrolytes

Reducing impedance to ionic flux in capacitive deionization with Bi-tortuous activated carbon electrodes coated with asymmetrically charged polyelectrolytes

Rapid Inversion of Surface Charges in Heteroatom‐Doped Porous Carbon: A Route to Robust Electrochemical Desalination

Hazardous wastes treatment technologies

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