Tracking the structural arrangement of ions in carbon supercapacitor nanopores using in situ small-angle X-ray scattering

Prehal, Christian; Weingarth, Daniel; Perre, Emilie; Lechner, R. T.; Amenitsch, Heinz; Paris, Oskar; Presser, Volker

doi:10.1039/c5ee00488h

Cited by 141 publications

(146 citation statements)

References 55 publications

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“…57 Forse et al 26 introduced the so-called charging mechanism parameter to account for different charging mechanisms taking place in the positive and negative electrodes. New experimental techniques, including nuclear magnetic resonance spectroscopy, 58 X-ray transmission, 59 electrochemical quartz crystal microbalance, 57 and infrared spectroscopy, 60 as well as molecular dynamic simulations 61 have established that the electrolyte, electrode constituent materials, and the polarization of the electrode could affect the charging mechanism of EDLC electrodes and thus the heat generation therein.…”

Section: Introductionmentioning

confidence: 99%

Effects of Constituent Materials on Heat Generation in Individual EDLC Electrodes

Munteshari

Lau

Ashby

et al. 2018

J. Electrochem. Soc.

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This study aims to investigate the effect of electrode composition on heat generation in electric double layer capacitor (EDLC) electrodes under galvanostatic cycling. EDLCs consist of two identical electrodes usually made of a mixture of (i) carbon-based material, (ii) binder, and (iii) other conductive additives. These constituents were found to influence the capacitance and internal resistance of the device and the heat generation rate in the positive and negative electrodes. Indeed, the heat generation rate was measured using an isothermal calorimeter in both electrodes of five EDLC devices with different electrode compositions but the same electrolyte consisting of 1 M LiPF 6 in EC:DMC. The reversible heat generation rates at the positive and negative electrodes were nearly identical in absence of CMC. However, in devices containing CMC, the reversible heat generation rate in the positive electrode was significantly larger than that in the negative electrode. Such asymmetric heating was attributed to asymmetry in the charging mechanism due to the overscreening effect caused by interactions between the anionic functional groups of CMC and the cations at the negative electrode. Electric double layer capacitors (EDLCs) have received significant attention in recent years for electrical energy storage applications in particular those requiring rapid charging/discharging, such as regenerative braking in electric vehicles, 1 smart grids, 2 and renewable energy harvesting systems.3-5 Indeed, EDLCs can provide higher power density, higher cycle efficiency, and longer lifetime than batteries. 4,6 EDLC devices consist typically of two carbon-based electrodes partitioned by a separator immersed in aqueous or organic electrolytes. EDLCs store electrical energy in the electrical double layer of ions forming at electrode/electrolyte interface.Heat generation in EDLC is a major concern since these devices are usually cycled under high current density resulting in excessive temperature rise.7 This, in turn, can lead to (i) accelerated cell aging, [8][9][10] (ii) increased self-discharge rates, 9,11 and possibly (iii) electrolyte decomposition and evaporation. 9,12 Heat generation in EDLCs can be classified into irreversible and reversible heat generation rates. 7,[13][14][15][16][17] Irreversible heat generation has been attributed, both theoretically and experimentally, to Joule heating. 7,9,11,[13][14][15][16][17][18][19][20] It is constant throughout the EDLC cell and equal to the product of the EDLC internal resistance and the square of the imposed current. 7,[14][15][16] On the other hand, reversible heat generation rate in the entire device was theoretically and experimentally found to be exothermic during charging and endothermic during discharging.7,14-16 The time-averaged reversible heat generation over a charging step was shown to be proportional to the imposed current under galvanostatic cycling.7,14-16 Experimentally, reversible heat generation has been assumed to be identical in both the positive and negative e...

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Section: Introductionmentioning

confidence: 99%

Effects of Constituent Materials on Heat Generation in Individual EDLC Electrodes

Munteshari

Lau

Ashby

et al. 2018

J. Electrochem. Soc.

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“…1.2, which are formed in the micropores inside the carbon particles [29][30][31][32]. These EDLs contain three types of charge: electronic, chemical and ionic.…”

Section: Capacitive Deionizationmentioning

confidence: 99%

“…Consequently, feed water flowing through the cell is desalinated. Ions are adsorbed in the micropores of the electrodes, where electrical double layers (EDLs) are formed [29][30][31]. After the electrodes are saturated with salt, they are discharged and ions desorb.…”

Section: Introductionmentioning

confidence: 99%

“…For electrodes based on carbon, as will be considered in this Chapter, during the adsorption step, ions are stored in electrical double layers (EDLs) formed in the electrodes [29,30]. For every electron transported from one electrode to the other, in both electrodes a counterion can adsorb in these EDLs, or a co-ion can desorb, see Chapter 2.…”

Section: Introductionmentioning

confidence: 99%

“…In CDI with porous carbon electrodes, ions are adsorbed into electrical double layers (EDLs) that are formed in the micropores of the electrodes [29][30][31][32]. For each electron transported from one electrode to the other, either a counterion can be adsorbed into the EDL (desired), or a co-ion can be desorbed (undesired).…”

Section: Introductionmentioning

confidence: 99%

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Desalination with porous electrodes : Mechanisms of ion transport and adsorption

Dykstra¹

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Discovering a Dual‐Buffer Effect for Lithium Storage: Durable Nanostructured Ordered Mesoporous Co–Sn Intermetallic Electrodes

Park

Yoon

Shon

et al. 2016

Adv Funct Materials

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Lithiation–delithiation reactions in Li‐ion batteries do exhibit a huge electrochemically driven volume change of the anode material between the lithium‐free and lithiated‐host states, which results in a gradually fading capacity. Minimizing this volume change of the electrode during cycling is essential to achieve stable electrochemical behavior and thus for innovating design of electrode materials for Li storage. Here, ordered mesoporous CoSn intermetallic anode materials with various Co/Sn atomic ratios are developed. A dual‐buffer effect is discovered that accommodates the volume changes in the electrode material by not only repeatedly generating void nanospaces but also by incorporating electrochemically inactive elements. Novel insights into the nanostructural changes of electrode materials during the lithiation–delithiation process are obtained by in operando small angle X‐ray scattering. The degrees of volume change and nanoscopic order are found to be highly dependent on the Co contents in the mesoporous CoSn intermetallic anode materials, being possible to achieve a durable nanostructured electrode upon prolonged cycling.

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Tracking the structural arrangement of ions in carbon supercapacitor nanopores using in situ small-angle X-ray scattering

Abstract: In situ small-angle X-ray scattering gives new insights into global ion exchange as well as into local re-arrangement of ions across the nanopores of activated carbon supercapacitors.

Cited by 141 publications

References 55 publications

Effects of Constituent Materials on Heat Generation in Individual EDLC Electrodes

Effects of Constituent Materials on Heat Generation in Individual EDLC Electrodes

Desalination with porous electrodes : Mechanisms of ion transport and adsorption

Discovering a Dual‐Buffer Effect for Lithium Storage: Durable Nanostructured Ordered Mesoporous Co–Sn Intermetallic Electrodes

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