Organosilicon (OS) electrolytes have been developed as a viable alternative to conventional carbonate electrolytes for lithium ion batteries.^1,2 A recent trend in the Li-ion industry toward adoption of new materials is driven by the desire to deploy larger capacity batteries under broader operating conditions. New advanced Li-ion chemistries to meet these requirements often require electrolytes with enhanced thermal and electrochemical stability that provide performance across a wide temperature range.

Silatronix has developed and synthesized an entirely new class of OS molecules with superior thermal, chemical, and electrochemical properties. The leading candidate from this new class is OS3 which showcases greatly enhanced stability and performance attributes in Li-ion batteries. Specifically, OS3 provides benefits such as lower anode and cathode impedance and reduced gas generation in multiple Li-ion chemistries.

The role of the Li⁺ solvation structure in the determination of electrolyte performance, including the formation, stability, and performance of the SEI layer, has been investigated using multiple analytical techniques. These techniques include FTIR spectroscopy, Raman spectroscopy⁴, NMR spectroscopy³, and electrospray ionization mass spectrometry (ESI-MS)⁵.

In this work, we focus on understanding the unique role that OS3 plays in the Li⁺ solvation sheath with NMR spectroscopy using multiple nuclei to simultaneously probe the anion, cation, and solvent environments. Data collected for electrolytes containing solvents with a variety of functional groups finds that the NMR response to Li⁺ coordination is identical for multiple solvents with the same coordinating functionality (e.g., carbonate, nitrile, etc). Therefore, the solvation behavior of multiple solvents in complex electrolytes can be deconvoluted and individually understood. The strong participation of OS solvents in the Li⁺ solvation sheath, including the displacement of strong carbonate solvents such as EC. has been demonstrated in multiple electrolytes using NMR spectroscopy and ESI-MS.

*RJH and RW have a financial interest in the outcome of this work.

References:

1. Rossi, N. A. A.; West, R., Silicon-containing liquid polymer electrolytes for application in lithium ion batteries. Polymer International 2009, 58, (3), 267-272.

2. Zhang, L.; Zhang, Z.; Harring, S.; Straughan, M.; Butorac, R.; Chen, Z.; Lyons, L.; Amine, K.; West, R., Highly conductive trimethylsilyl oligo(ethylene oxide) electrolytes for energy storage applications. Journal of Materials Chemistry 2008, 18, (31), 3713-3717.

3. Yang, L.; Xiao, A.; Lucht, B.; Investigation of solvation in lithium ion battery electrolyte by NMR spectroscopy. Journal of Molecular Liquids 2010, 154, (2–3), 131-133.

4. Morita, M.; Asai, Y.; Yoshimoto, N.; Ishikawa, M.; A Raman spectroscopic study of organic electrolyte solutions based on binary solvent systems of ethylene carbonate with low viscosity solvents which dissolve different lithium salts. J. Chem. Soc., Faraday Trans., 1998, 94, 3451-3456.

5. von Wald Cresce, A.; Borodin, O.; Xu, K.; Correlating Li+ solvation sheath structure with interphasial chemistry on graphite. J. Phys. Chem. C, 2012, 116 (50), pp 26111–26117