Solvation and Dynamics of Lithium Ions in Carbonate-Based Electrolytes during Cycling Followed by Operando Infrared Spectroscopy: The Example of NiSb₂, a Typical Negative Conversion-Type Electrode Material for Lithium Batteries

Abstract

Conversion-type electrode materials show extremely interesting performance in terms of capacity, which is however usually associated with bad Coulombic efficiency. The latter is mainly the consequence of the relentless evolution of solid electrolyte interphase (SEI) formed and/or dissolved during conversion/back-conversion reactions on the continuously reshaping active material surface. The thorough comprehension of the dynamic processes occurring during cycling in a working electrochemical cell, such as solvation/desolvation of ionic species and formation/dissolution of the SEI at the electrode/ electrolyte interface, is thus of utmost relevance in the study of electrochemical mechanism and performance of conversion-type electrode materials. Operando Fourier transform infrared (FTIR) spectroscopy, one of the methods of choice for the study of such phenomena, was applied to study the dynamic interfacial properties of NiSb 2 , a representative intermetallic conversion-type electrode material for Li batteries, during cycling in the presence of a commercial electrolyte based on LiPF 6 dissolved in a mixture of ethylene carbonate (EC) and dimethyl carbonate (DMC). Using a specifically developed in situ ATR-IR electrochemical cell, it was possible to correlate the electrochemical processes to the ratio between solvent molecules associated with Li + ions and free solvent molecules and thus to follow the dynamic evolution of the concentration of lithium in the electrolyte during cycling.

Cobalt Carbodiimide as Negative Electrode for Li‐Ion Batteries: Electrochemical Mechanism and Performance

“…Profile matching and calculation of the cell parameters were refined using the LeBail method . In situ Fourier transform infrared spectroscopy (FT‐IR) analyses were carried out on a Nicolet Magna FTIR spectrometer equipped with a liquid nitrogen cooled MCT−A detector in the Attenuate Total Reflection (ATR) geometry using a specifically designed in situ cell . The cell was obtained by modifying the Raman spectroscopy in situ electrochemical cell used elsewhere, by replacing the quartz window with the diamond probe of the ATR module.…”

Cation−Solvent, Cation−Anion, and Solvent−Solvent Interactions with Electrolyte Solvation in Lithium Batteries

“…[6b,11] There are great achievements in understanding electrolyte solvation structure and promoting battery performance. [12] If the solvation effect on fundamental interactions in electrolytes, such as the cation-solvent, cation-anion, and solvent-solvent interactions, can be built, a deep understanding of electrolyte solvation at the atomic level can be achieved. This is of great importance for further electrolyte exploration and interfacial regulation of working rechargeable batteries.In this contribution, the interactions of cation-solvent, cation-anion, and solvent-solvent in both vacuum and solution conditions were systematically investigated through density functional theory (DFT) calculations.…”

Effect of standard light illumination on electrolyte’s stability of lithium-ion batteries based on ethylene and di-methyl carbonates

“…The solvation shell of lithium cation has been extensively studied to better understand the interplay between the electrolyte’s structure and the performances within lithium-ion batteries 26–30 . Nontheless, Ponnuchamy et al .…”