Kinetic Behavior of the Anion Intercalation/De-intercalation into the Graphite Electrode in Organic Solution

Abstract

Electrochemical anion intercalation/de-intercalation into the graphite electrode generally takes place at high electrode potential of over 4.5 V (Li + /Li), so it is attractive as the positive electrode reaction for the post lithium-ion batteries. In this study, the kinetic behavior of the anion intercalation reaction in the organic solution is studied.The interfacial activation energy of anion species is as low as about 25 kJ mol −1 , which is much lower than that of Li + -ion. The result means the anion intercalation reaction is essentially fast and therefore, it is suitable for the high power batteries. In addition, the activation energy is not influenced by the solvation ability in the solution and from the result, we conclude that the interfacial activation barrier will exist on the graphite electrode side, contrary to the Li + -ion case.

Influence of Strong Ionic Interaction on the Kinetics of Graphite Intercalation Compound Formation

“…Here, the molar ratio of the metal cations (Mg 2+ and Li + ) to TFSA anions, rather than the molar concentration, was used as the abscissa axis to account for changes in the solution volume due to salt addition. The activation energy for the ionic liquid‐only electrolyte was 24 kJ mol −1 , which is almost identical to that reported for the 1.0 m LiTFSA/propylene carbonate solution [15] . Generally, the interaction between anions and organic solvents is negligible in organic electrolytes; therefore, this relatively low activation energy may be the result of free TFSA anions interacting with DEME cations intercalated into graphite.…”

“…The activation energy for the ionic liquid-only electrolyte was 24 kJ mol À 1 , which is almost identical to that reported for the 1.0 m LiTFSA/propylene carbonate solution. [15] Generally, the interaction between anions and organic solvents is negligible in organic electrolytes; therefore, this relatively low activation energy may be the result of free TFSA anions interacting with DEME cations intercalated into graphite. The subsequent addition of salt resulted in a gradual increase in the activation energy, indicating that metal cations interact with TFSA anions.…”

“…Previously, we investigated the kinetic behavior of intercalation/deintercalation of cations and anions into graphite from the perspective of the interaction between ions and organic solvent molecules. [13][14][15][16] In particular, it was found that the desolvation of ions, which disrupts the interaction between ions and solvent molecules, is an important step in determining the activation barrier for interfacial ion-transfer reactions on graphite. However, it is unclear whether the concept of desolvation and activation energy can be applied to ionic liquid electrolytes.…”

Dynamic Study of Intercalation/Deintercalation of Ionic Liquids in Multilayer Graphene Using an Alternating Current Raman Spectroscopy Technique

“…These investigations have mainly looked at HOPG and have used a wide range of characterization techniques/methods, including the combination of Fourier transform infrared (FTIR) and Raman spectroscopy, by X-ray diffraction, thermogravimetry, and the above structural characterizing techniques . Kinetic studies of anionic intercalation/deintercalation into the graphite electrode have been studied using lithium ions solely based on electrochemical measurements (i.e., not structural measurements) . As such, dynamic optical, vibrational, and structural techniques that can be performed in situ as a function of time are much needed.…”

The Influence of the Coordination on the Kinetic Behavior of the Anion Intercalation/De-Intercalation into the Graphite Electrode

“…From the result, we concluded the interaction with solvent species was so weak that the activation barrier existed in the electrode side. 12 Recently, the concentrated solutions such as solvation ionic liquids or hydrate melts have been paid much attention due to their specific electrochemical behaviors. [13][14][15] Dual carbon cells also require the concentrated solution because the carrier ions are supplied from the solution, not from the electrode, which causes the depletion of carrier ions in the solution and the following increase in the internal resistance during the charge process.…”