<i>In situ</i> interferometry study of ionic mass transfer phenomenon during the electrodeposition and dissolution of Li metal in solvate ionic liquids

Miki, Akinori; Nishikawa, Kei; Kamesui, Go; Matsushima, Hisayoshi; Ueda, Mikito; Rosso, Michel

doi:10.1039/d1ta02666f

Cited by 10 publications

(18 citation statements)

References 46 publications

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“…On the anode side, D anode = (3.2–3.6) × 10 –7 cm 2 s –1 ; thus, D anode is slightly smaller than D cathode . This finding is consistent with the results of our previous study . The difference in D between the two electrodes may be ascribed to the difference in the concentration close to the electrodes.…”

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confidence: 93%

“…Here, the color changes indicate the optical phase changes of the electrolyte that correspond to changes in M LiTFSA/SL . 9 The interferometry images also reveal the dendrite growth of the electrodeposited Li metal.…”

mentioning

confidence: 98%

“…For the stable operation of Li metal electrodes, maintaining the uniformity of the electrode surface morphology is critical. Numerous studies have been conducted on the correlation between the electrode surface morphology and solid electrolyte interphase (SEI) layer composition using X-ray photoelectron spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). − However, only a few studies have involved analyses of the morphology of Li deposits with respect to the ionic mass transfer close to the electrode. − Generally, metal electrodeposition is considerably influenced by ionic mass transfer within the electrolyte. − As the electrochemical reaction is initiated, a concentration gradient forms close to the electrode, and the diffusion of ionic species is enhanced. Uniform deposition morphology can be obtained with sufficient mass transfer of metal cations to the electrode surface.…”

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confidence: 99%

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Mass Transfer during Electrodeposition and Dissolution of Li Metal within Highly Concentrated Electrolytes

et al. 2022

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Understanding the mechanisms of electrodeposition and dissolution of Li metal is necessary to control the morphological variations of Li metal anodes for next-generation batteries. Herein, the morphology of electrodeposited Li in a sulfolane-based highly concentrated electrolyte (HCE) and its correlation with the concentration profiles close to the electrodes were investigated. The decomposition of the solvent and anions on the electrodeposited Li surface caused significant changes in the morphology and solid electrolyte interphase layer thickness. During electrochemical dissolution, the Li+ surface concentration at the electrode became supersaturated, and the number of anions coordinated to Li+ increased at high current densities. The supersaturation state induced divergence of the electrode potentials. Therefore, the electrode reaction progress is correlated with the mass transfer within HCEs. Understanding the relationship between mass transfer and morphological variation in the Li metal electrode should promote the development of a strategy for using HCEs in Li metal batteries.

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Mass Transfer during Electrodeposition and Dissolution of Li Metal within Highly Concentrated Electrolytes

et al. 2022

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“…Compared to the conventional aqueous or organic electrolytes, ILs have a complex ionic structure and a high ionic concentration, resulting in a peculiar solvation environment and a highly ordered structure on the electrode. Several experimental methods, such as electrochemical impedance spectroscopy, − in situ interferometry, and nuclear magnetic resonance (NMR) spectroscopy, , were used to investigate the Li + -ion transport process near the electrode, indicating that the low transport number of Li + ion in IL electrolytes can limit the discharging current due to the polarization in the IL electrolytes , and that the change in ionic concentration near the electrode alters the local viscosity . Scanning electron microscopy (SEM) − ,, is a powerful method to visualize the electrode surface in an ex situ manner after the Li electrodeposition process in ILs.…”

Section: Introductionmentioning

confidence: 99%

“…Several experimental methods, such as electrochemical impedance spectroscopy, − in situ interferometry, and nuclear magnetic resonance (NMR) spectroscopy, , were used to investigate the Li + -ion transport process near the electrode, indicating that the low transport number of Li + ion in IL electrolytes can limit the discharging current due to the polarization in the IL electrolytes , and that the change in ionic concentration near the electrode alters the local viscosity . Scanning electron microscopy (SEM) − ,, is a powerful method to visualize the electrode surface in an ex situ manner after the Li electrodeposition process in ILs. As for the in situ experimental methods to study Li electrodeposition in ILs, scanning tunneling microscopy (STM), optical microscopy observation, , atomic force microscopy (AFM), , and electrochemical quartz crystal microbalance (EQCM) , were used to study not only the electrode surface morphology − but also the IL structure on the electrode. ,− …”

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confidence: 99%

In Situ Electrochemical Surface Plasmon Resonance Study on Lithium Underpotential Deposition and Stripping in Bis(fluorosulfonyl)amide-Based Ionic Liquids

et al. 2022

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To sensitively detect the electrode surface roughness change in the initial process of the lithium electrodeposition/dissolution processes in ionic liquids (ILs), electrochemical surface plasmon resonance (ESPR) measurements were performed in an in situ manner on a gold electrode in a glyme-Li salt solvate IL, tetraglyme/lithium bis(fluorosulfonyl)amide ([Li(G4)+][FSA–]), and an IL, 1-butyl-3-methylimidazolium bis(fluorosulfonyl)amide ([C4mim+][FSA–]), containing 100 mM Li+[FSA–]. The SPR angle shifts (ΔθSPR) were tracked simultaneously with the repetitively recorded cyclic voltammograms (CVs) of the Li underpotential deposition (UPD)/underpotential stripping (UPS). ΔθSPR increased/decreased in the UPD/UPS processes, sensitively responding to the refractive index change at the IL/electrode interface. The time derivative ΔθSPR curves basically reproduced CVs but were significantly less influenced by residual current, indicating that ESPR was an effective in situ method to track the Li UPD/UPS processes. In [Li(G4)+][FSA–], the shift in ΔθSPR per deposited Li amount did not change as the CV scan was repeated, indicating no change in surface roughness. In contrast, in [C4mim+][FSA–], the same parameter increased with an increase in the scan number, reflecting the increase in surface roughness as confirmed by Fresnel reflectivity simulations. The comparison of ESPR results with the simulations suggests that for both ILs, the surface of the deposited Li layer was smoothened during the period after the Li UPD and before the Li UPS in CVs.

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Characterizing Ion Transport in Electrolytes via Concentration and Velocity Profiles

Mistry

Srinivasan

Steinrueck

2023

Advanced Energy Materials

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if not controlled. Thus, characterizing, quantifying, and understanding electrolyte transport is critical to performance, degradation, and safety behavior of batteries and other electrochemical systems. [1] Historically, efficacy of an electrolyte for transporting ions has been characterized in terms of its conductivity, κ, and even today many studies use conductivity to screen electrolytes. [12,13] As the understanding of ion transport advanced, additional transport properties such as cation transference number, t 0 + , and salt diffusivity, D, have been identified to dictate the ion transport behavior. Interestingly, a high conductivity electrolyte does not necessarily exhibit high transference or diffusion. [14] As a result, the electrolyte transport behavior can be limited by a property other than conductivity, and one must examine all the relevant transport properties to assess the usefulness of an electrolyte for the desired battery application. Unfortunately, unlike conductivity, other electrolyte transport properties are not straightforward to measure. [15][16][17][18] This is particularly true for many practically relevant battery electrolytes which behave as concentrated (i.e., nonideal, nondilute) solutions and dramatically influence the battery operation. [2,5,[19][20][21][22] To underpin the true properties describing transport in such concentrated electrolytes, standard electroanalytical techniques [23] relying on interpreting current or potential measurements to estimate electrolyte transport properties have to be suitably modified. For example, the Bruce-Vincent test data must be interpreted using additional properties to characterize t 0 + . [24] In recent years, alternative measurement techniques have evolved that instead of relying on macroscopic current or potential data, characterize species velocity [25] or concentration profiles. [26] Such measurements open new doors for characterizing electrolyte transport. Since most of these measurements obtain spatially and temporally varying profiles, their analysis is intricately linked to concentrated solution theory (CST) describing general electrolyte transport behavior. Accordingly, we first discuss CST and then various experimental techniques capturing different profiles. We subsequently offer our perspective on developing new tools and techniques as well as using them to quantify transport in more complex electrolytes. We should note that different molecular mechanisms jointly ascribe the specific values of these continuum transport properties across different electrolytes. [27][28][29][30] While establishing such a structure-property correlation is critical to designing new electrolytes, [31][32][33] quantifying meaningful electrolyte transport properties such that its behavior can be accurately predicted across different electrochemical configurations is necesary to designing Current flowing through an electrolyte is accompanied by continuum motion of ions and solvent, species concentration profiles, and the electric field. While, historically...

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In situ interferometry study of ionic mass transfer phenomenon during the electrodeposition and dissolution of Li metal in solvate ionic liquids

Abstract: A digital holographic microscope was used to observe the Li+ concentration profile in-situ, accompanied by the electrodeposition and electrochemical dissolution of Li metal in a solvate ionic liquid. The concentration...

Cited by 10 publications

References 46 publications

Mass Transfer during Electrodeposition and Dissolution of Li Metal within Highly Concentrated Electrolytes

Mass Transfer during Electrodeposition and Dissolution of Li Metal within Highly Concentrated Electrolytes

In Situ Electrochemical Surface Plasmon Resonance Study on Lithium Underpotential Deposition and Stripping in Bis(fluorosulfonyl)amide-Based Ionic Liquids

Characterizing Ion Transport in Electrolytes via Concentration and Velocity Profiles

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