Investigating the Electrode Kinetics of the Li/Li⁺ Couple in a Wide Range of Room Temperature Ionic Liquids at 298 K

Abstract

Cyclic voltammetry experiments are carried out using a 0.1 M Li + solution in 12 different room temperature ionic liquids (RTILs), [C 4 mpyrr][NTf 2 ], [C 4 dmim][NTf 2 ], [N 2,1,1,3 ][NTf 2 ], [N 6,2,2,2 ][NTf 2 ], [C 4 mim][OTf], [C 4 mpyrr][N(CN) 2 ], [C 2 mim][NTf 2 ], [P 14,6,6,6 ][FAP], [C 4 py][NTf 2 ], [C 4 mim][PF 6 ], [C 4 mim][NTf 2 ], and [N 1,8,8,8 ][OTf], on a Ni microelectrode to investigate the deposition and stripping of lithium from the electrode surface. [C 4 mpyrr][N(CN) 2 ], [C 2 mim][NTf 2 ], [P 14,6,6,6 ][FAP], [C 4 py][NTf 2 ], [C 4 mim][PF 6 ], [C 4 mim][NTf 2 ], and [N 1,8,8,8 ][OTf] did not have a wide enough potential window to observe the deposition and stripping of bulk lithium. In the experimental data recorded for [C 4 mpyrr][NTf 2 ], [C 4 dmim][NTf 2 ], [N 2,1,1,3 ][NTf 2 ], [N 6,2,2,2 ][NTf 2 ], and [C 4 mim][OTf], a single stripping peak for bulk lithium is seen, and kinetic data for the Li/Li + couple are extracted by comparison with computational simulations. The electrochemical rate constant, k 0 , is found to have values ranging from (1.3 • 10 -6 to 1.2 • 10 -5 ) cm • s -1 . Diffusion coefficients for the Li + ion in these five RTILs are also reported.

X‐ray Photoelectron Spectroscopy of Pyridinium‐Based Ionic Liquids: Comparison to Imidazolium‐ and Pyrrolidinium‐Based Analogues

“…Pyrrolidinium‐based ionic liquids have been investigated with a great deal of interest for the use in electrochemistry due to their greater stability when compared to imidazolium analogues, in terms of cation electrochemistry reduction 27. Furthermore, pyridinium‐based ionic liquids have also been reported to be more thermally stable when compared to imidazolium analogues 10.…”

Recent Advances in Voltammetry

“…Extensive modeling of a wide diversity of voltammetric systems has been undertaken using small microelectrodes in order to provide a better possibility of extracting kinetic parameters. Systems studied include O 2 /O 2 .− , Br − /Br 2 , nitrobenzenes, aryl amines, NO 2 /NO 2 − /NO 2 + , I − /I 2, aromatic diamines, arenes, Li/Li + , benzoquinone, hydroquinone, and H + /H 2 . In many cases the values of k 0 obtained correspond to quasi‐reversible behaviour and, as such, do not provide a perfect test of the validity of Butler–Volmer kinetics since the behaviour is approximately Nernstian.…”

Kinetics of Na|CF x and Li|CF x systems

“…Cyclic voltammetry experiments on Pt and Ni electrodes gave similar value of charge transfer rate constant k o ∼ 10 −5 cm s −1 for both Li/Li + [60,62] and Na/Na + [61] systems. In the case of metallic lithium and sodium electrodes a protective layer of the solid electrolyte interphase (SEI) is formed.…”

“…Charge transfer process for sodium is slower in comparison to that characteristic of lithium; however, 3-4 orders of magnitude faster in comparison to that characteristic of CF x cathode. Kinetics of Li/Li + and Na/Na + was also investigated in ionic liquids [60][61][62][63][64][65]. In the literature, the charge transfer reaction is described by exchange current density, j o , rate constant k o or corresponding resistance R ct , which are mutually related.…”