Electrochemistry of graphite intercalation compounds

Noel, M.; Santhanam, R.

doi:10.1016/s0378-7753(97)02675-x

Cited by 203 publications

(141 citation statements)

References 121 publications

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“…21,23 Considering the relationship between intercalation and electrowetting that we have described, we found that similar effects to those reported above for ClO4 -were found with SO4 This study further confirms that ion-intercalation/de-intercalation of specific ions (ClO4 -), rather than the anodic formation of graphite oxide or, water oxidation is responsible for the electrowetting of graphite that we observe. …”

Section: Anion Effect On Electrowettingsupporting

confidence: 91%

“…However, there is no intercalation of PO4 3-ions into graphite. 21,22,23 In the studies herein, we control the potential to avoid exfoliation and explore the factors that promote electrowetting and its associated timescale. Our work provides intriguing insights into the effect of step edge density on electrowetting, with the highest quality HOPG samples that have low step edge density (but monolayer steps) leading to more facile ion intercalation/de-intercalation and thus extensive electrowetting.…”

Section: Introductionmentioning

confidence: 99%

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Low-Voltage Voltammetric Electrowetting of Graphite Surfaces by Ion Intercalation/Deintercalation

2016

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We demonstrate low-voltage electrowetting at the surface of freshly cleaved highly oriented pyrolytic graphite (HOPG). Using cyclic voltammetry (CV), electrowetting of a droplet of sodium perchlorate solution is observed at moderately positive potentials on high-quality (low step edge coverage) HOPG, leading to significant changes in contact angle and relative contact diameter that is comparable to the widely studied electrowetting on dielectric (EWOD) system, but over a much lower voltage range. The electrowetting behavior is found to be reasonably fast, reversible and repeatable for at least 20 cyclic scans (maximum tested). In contrast to classical electrowetting, e.g. EWOD, the electrowetting of the droplet on HOPG occurs with the intercalation/de-intercalation of anions between the graphene layers of graphite, driven by the applied potential, observed in the CV response, and detected by X-ray photoelectron spectroscopy. The electrowetting behavior is strongly influenced by those factors that affect the extent of the intercalation/de-intercalation of ions on graphite, such as scan rate, potential polarity, quality of the HOPG substrate (step edge and step height), and type of anion in the solution. In addition to perchlorate, sulfate salts also promote electrowetting, but some other salts do not. Our findings suggest a new mechanism for electrowetting based on ion intercalation and the results are of importance to fundamental 2 electrochemistry, as well as diversifying the means by which electrowetting can be controlled and applied.3

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Section: Anion Effect On Electrowettingsupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Low-Voltage Voltammetric Electrowetting of Graphite Surfaces by Ion Intercalation/Deintercalation

2016

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“…1,2 Currently, the predominantly used donor-type GIC is LiC x . The LiC x /C x redox couple is the major active compound for state-of-the-art negative electrodes in lithium ion batteries.…”

mentioning

confidence: 99%

Reversible Intercalation of Bis(trifluoromethanesulfonyl)imide Anions from an Ionic Liquid Electrolyte into Graphite for High Performance Dual-Ion Cells

Placke

Fromm

Lux

et al. 2012

J. Electrochem. Soc.

307

345

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Dual-graphite cells have been proposed as electrochemical energy storage systems using graphite as both, the anode and cathode, whereas the electrolyte cations intercalate into the negative electrode and the electrolyte anions intercalate into the positive electrode during charge. On discharge, cations and anions are released back into the electrolyte. In this contribution, we present highly promising results for "dual-ion cells" based on intercalation of bis(trifluoromethanesulfonyl)imide anions into a graphite cathode from an ionic liquid-based electrolyte, namely N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (Pyr 14 TFSI). As the compatibility of this ionic liquid with graphitic anodes is relatively poor, metallic lithium and lithium titanate (Li 4 Ti 5 O 12 ) are used as anode. As both cations and anions participate in the charge/discharge reaction and other anode materials than graphite are possible, we propose the name "dual-ion cells" for these systems. The cell performance was studied in terms of cut-off voltage, temperature, cycling stability, self-discharge and rate performance. Depending on the cut-off voltage and temperature, coulombic efficiencies of more than 99 % and specific discharge capacities exceeding 100 mAh g −1 (based on graphite cathode weight) were achieved. Furthermore, this system provides an excellent cycling stability and capacity retention above 99 % after 500 cycles, outperforming reported organic solvent-based dual-graphite or dual-ion cells. Graphite is a redox-amphoteric intercalation host and therefore cations and anions can be electrochemically intercalated at different potentials yielding so-called donor-type or acceptor-type graphite intercalation compounds (GICs).1,2 Currently, the predominantly used donor-type GIC is LiC x . The LiC x /C x redox couple is the major active compound for state-of-the-art negative electrodes in lithium ion batteries. [3][4][5][6][7] Compared to the limited number of cationic intercalation guests, there is a broad spectrum of different anions capable to form acceptor-type GICs. Examples are hexa-or tetrafluoride guest species, e. g. PF 6− , AsF In 1938, Rüdorff and Hofmann developed the first ion transfer or rocking chair cell based on the shuttling of HSO 4 − anions between two graphite electrodes ( Figure 1a).14 This cell can be considered as the ancestor of the well-known lithium-ion cell, where lithium cations are transferred between two insertion electrodes during the charge/discharge process (Figure 1b). 3 In the 1990s, a rechargeable electrochemical energy storage system, using graphite as positive and negative electrode material in combination with a non-aqueous electrolyte has been introduced by and Carlin et al. 27,28 Carlin et al. investigated the reductive and oxidative intercalation of different cations and anions from ionic liquid-based electrolytes (without any additional lithium salt), such as 1-ethyl-3-methylimidazolium hexafluorophosphate (EMI + PF 6 − ). This system, a so-called dual-graphite cell, was bas...

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“…X can be any number of monomers in a conducting polymer or can be another oxidizable host for anions, such as graphite. 40,41 The full cell reaction is the sum of the positive and negative electrode reactions (cell discharge from left to right):…”

Section: Proposed Electrode Reactionsmentioning

confidence: 99%

Rechargeable aluminum batteries with conducting polymers as positive electrodes

Hudak

2013

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This report is a summary of research results from an Early Career LDRD project conducted from January 2012 to December 2013 at Sandia National Laboratories. Demonstrated here is the use of conducting polymers as active materials in the positive electrodes of rechargeable aluminum-based batteries operating at room temperature. The battery chemistry is based on chloroaluminate ionic liquid electrolytes, which allow reversible stripping and plating of aluminum metal at the negative electrode. Characterization of electrochemically synthesized polypyrrole films revealed doping of the polymers with chloroaluminate anions, which is a quasi-reversible reaction that facilitates battery cycling. Stable galvanostatic cycling of polypyrrole and polythiophene cells was demonstrated, with capacities at near-theoretical levels (30-100 mAh g -1 ) and coulombic efficiencies approaching 100%. The energy density of a sealed sandwich-type cell with polythiophene at the positive electrode was estimated as 44 Wh kg -1 , which is competitive with state-of-the-art battery chemistries for gridscale energy storage. 4 ACKNOWLEDGMENTS

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Electrochemistry of graphite intercalation compounds

Cited by 203 publications

References 121 publications

Low-Voltage Voltammetric Electrowetting of Graphite Surfaces by Ion Intercalation/Deintercalation

Low-Voltage Voltammetric Electrowetting of Graphite Surfaces by Ion Intercalation/Deintercalation

Reversible Intercalation of Bis(trifluoromethanesulfonyl)imide Anions from an Ionic Liquid Electrolyte into Graphite for High Performance Dual-Ion Cells

Rechargeable aluminum batteries with conducting polymers as positive electrodes

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