Graphite-based Li-ion batteries require the formation of a solid electrolyte interphase (SEI) on the surface of the anode to prevent solvent co-intercalation and graphite exfoliation. Materials such as vinylene carbonate (VC) and fluoroethylene carbonate (FEC) that have been successfully deployed as SEI layer forming additives show limited utility under high voltage and high temperature conditions due to low electrochemical and/or thermal stability. 1-3 Development of Li-ion batteries that meet the needs of automotive and other electrification applications require advanced electrolyte additives that can support operation under extreme conditions. Koura has developed fluorinated additives that demonstrate improved stability and performance over conventional SEI layer forming additives under the high temperature and high voltage conditions relevant to the automotive industry. In this study, the performance of Koura’s fluorinated additives was compared to common commercial additives in the multiple cell designs, including 4.3V Gr/NMC811, to identify candidates to replace VC and FEC. Testing included 45°C cycling and 60°C storage. It has been found that these materials reduce gassing and increase capacity retention during high-temperature battery operation. To gain a fundamental understanding of how these molecules function in the battery, including mechanisms of solvation, interfacial behavior, and bulk reactivity; and how the structure of the molecule contributes to its properties and behavior, comprehensive post-test analysis was conducted, including gas composition analysis and quantification via gas chromatography, bulk electrolyte composition analysis via NMR spectroscopy, and surface layer characterization via XPS and SEM. Also, performance of multiple structural variants was examined to develop a structure-property relationship to guide rational design of additives for advanced Li-ion batteries. This presentation will summarize Koura’s efforts to supply advanced fluorinated materials for Li-ion batteries that satisfy the arduous demands of current and future applications. Specifically, we will present data showing the capability of fluorinated Koura materials to replace and/or enable existing Li-ion additives under extreme operating conditions, specifically high temperature and/or voltage. Multiple structures will be compared, where appropriate, to highlight our fundamental understanding of the structure-property relationships critical to designing next generation materials. References: Tobias Teufl et al 2023 J. Electrochem. Soc. 170 020531 Daniel Pritzl et al 2017 J. Electrochem. Soc. 164 A2625 Hiroshi Haruna et al 2017 J. Electrochem. Soc. 164 A6278

Previously we investigated electrochemical properties [1] of various 2,3,4,5-tetraphenylsiloles (I) with different substituents attached to the Si atom. Major products include 1,2-dibenzoyl, 1,2-diphenylethene, tetraphenylfuran and tetraphenyldihydrofuran. Later [2] we explored the redox properties of four silafluorenes of type (II). Major products after CPE involve both aromatic hydrocarbons and siloxane derivatives. Recently [3] we studied the electrochemical redox properties of four spiro-derivatives (III) in which the central atom is C, Si, Ge or Sn, both by cyclic voltammetry and controlled potential electrolysis. The outcome from these measurements will be presented in this talk. It is noteworthy to indicate that each spiro derivative afford different products although their cyclic voltammograms are similar. References [1] A. Dhiman, Z.-R. Zhang, R. West, J. Y. Becker, J. Electroanal. Chem., 2004, 569, 15-22; A. Dhiman, Z.-R. Zhang, R. West, J. Y. Becker, J. Electroanal. Chem., 2004, 573, 139-146. [2] A. C. Herath, R. West, J.Y. Becker, J. Electroanal. Chem., 2014, 728, 118-122. [3] T. Golub-Sedinkin, A. C. Herath, R. West, and J. Y. Becker, ChemElectroChem , 2019, 6, 1–6; J.Y. Becker, unpublished results (2021). Figure 1

Previously we investigated electrochemical properties [1] of various 2,3,4,5-tetraphenylsiloles (I) with different substituents attached to the Si atom. Major products include 1,2-dibenzoyl, 1,2-diphenylethene, tetraphenylfuran and tetraphenyldihydrofuran. Later [2] we explored the redox properties of four silafluorenes of type (II). Major products after CPE involve both aromatic hydrocarbons and siloxane derivatives. Recently [3] we studied the electrochemical redox properties of four spiro-derivatives (III) in which the central atom is C, Si, Ge or Sn, both by cyclic voltammetry and controlled potential electrolysis. The outcome from these measurements will be presented in this talk. It is noteworthy to indicate that each spiro derivative afford different products although their cyclic voltammograms are similar. References [1] A. Dhiman, Z.-R. Zhang, R. West, J. Y. Becker, J. Electroanal. Chem., 2004, 569, 15-22; A. Dhiman, Z.-R. Zhang, R. West, J. Y. Becker, J. Electroanal. Chem., 2004, 573, 139-146. [2] A. C. Herath, R. West, J.Y. Becker, J. Electroanal. Chem., 2014, 728, 118-122. [3] T. Golub-Sedinkin, A. C. Herath, R. West, and J. Y. Becker, ChemElectroChem , 2019, 6, 1–6; J.Y. Becker, unpublished results (2021). Figure 1

Gas generation during Li-ion battery operation remains a problem that can affect both safety and operational lifetime of the battery. Electrolyte solvents are a key source of gas generation 1 and while gas-reducing additives have been identified, the underlying mechanisms require more study to fully understand the role between solvent structure and gas generation. Understanding of these gassing mechanisms can lead to optimized electrolyte systems with reduced gassing for the next generation of Li-ion batteries. Previous studies in the literature 2 have detailed the use of 13 C-labeled EC and DEC to identify the proportions of CO 2 and CO that are derived from solvent sources, which in turn can help inform mechanistic understanding on gas generation in Li-Ion Batteries. As previously studied by Silatronix®, electrolytes containing organosilicon (OS) materials show significantly reduced gas generation during high temperature storage and cycling in pouch cells primarily through CO 2 reduction. 3 Studies utilizing simple carbonate blends indicated that EC was the primary source of CO 2 ; therefore, it was hypothesized that OS materials reduce gassing by preventing EC decomposition during high temperature testing. In this work, 13 C-labeling was used to identify the sources of gas species in ternary carbonate electrolytes after both first charge (SEI formation 4 ) and high temperature storage (extended aging) to allow the effects of electrolyte additives gas reduction to be elucidated. Gas component analysis was performed using a calibrated GC-MS, providing identification and quantification of each gas species (labeled and unlabeled). These data give insight into how the labeled carbonate solvent may decompose into the observed gas phase products during the first charge (i.e., during SEI layer formation) and high temperature storage. Ethylene carbonate (EC) is found to be the primary source of ethylene generation, as well as a significant source of CO 2 and CO. With the addition of OS, the most notable effect is that the previously seen reduction in all gas components is due to not only reduction of EC-related sources, but reduction in non-EC gas sources as well. 1 Rowden, B.; Garcia-Araez, N., A Review of Gas Evolution in Lithium-Ion Batteries. Energy Rep . 2020 , 6, 10-18. 2 Onuki, M.; Kinoshita, S.; Sakata, Y.; Yanagidate, M.; Otake, Y.; Ue, M.; Deguchi, M., Identification of the Source of Evolved Gas in Li-Ion Batteries using 13 C-labeled Solvents. Journal of the Electrochemical Society 2008 , 155, A794. 3 Guillot, S.L.; Usrey, M.; Peña-Hueso, A.; Kerber, B.; Zhou, L.; Du, P.; Johnson, T., Reduced Gassing In Lithium Ion Batteries With Organosilicon Additives. Journal of the Electrochemical Society 2021 , 168, 030533. 4 Ktristiina Heiskanen, S.; Kim, J.; Lucht, B., Generation and Evolution of the Solid Electroyte Interphase of Li-Ion Batteries. Joule 2019 , Volume 3 Issue 10, 2322.

The release of gases through electrolyte decomposition is a problem of prominent concern in the Li-ion battery industry, due to the negative impact of gassing on cell safety and performance. The development of new electrolytes and additives is essential in enabling low-gassing batteries. Organosilicon (OS) molecules, which merge a silane with a Li+ coordinating functionality, have been developed by Silatronix® as additions to conventional carbonate electrolytes, demonstrating critical high thermal and voltage stability to enable next-generation Li-ion batteries. In this study we report performance testing and fundamental mechanistic studies to investigate gassing phenomena in advanced Li-ion chemistries under storage test conditions. Novel organosilicon nitriles developed by Silatronix® as well as common gas reducing additives (i.e. 1,3-propanesultone, succinonitrile) were evaluated in a 4.35 V Graphite/NMC622 (LiNi0.6Mn0.2Co0.2O2) multi-layer pouch cell. Potential synergies between OS materials and these additives were investigated. The dependence of gassing on electrolyte composition and test conditions was investigated, and connections between gassing behavior and electrode surface chemistry are also reported. Key experimental results show that all OS concentrations reduce gas generation during 60 °C storage, and higher OS content provides greater benefit. Overall, we show that organosilicon additives substantially reduce gassing from carbonate-based electrolytes while maintaining cell performance.

Understanding the characteristics of radicals formed from silicon-containing heavy analogues of alkenes is of great importance for their application in radical polymerization. Steric and electronic substituent effects in compounds such as phosphasilenes not only stabilize the Si=P double bond, but also influence the structure and species of the formed radicals. Herein we report our first investigations of radicals derived from phosphasilenes with Mes, Tip, Dur, and NMe(2)substituents on the P atom, using muon spin spectroscopy and DFT calculations. Adding muonium (a light isotope of hydrogen) to phosphasilenes reveals that: a) the electron-donor NMe(2)and the bulkiest Tip-substituted phosphasilenes form several muoniated radicals with different rotamer conformations; b) bulky Dur-substituted phosphasilene forms two radicals (Si- and P-centred); and c) Mes-substituted phosphasilene mainly forms one species of radical, at the P centre. These significant differences result from intramolecular substituent effects.

AbstractDas Verständnis der Eigenschaften von Radikalen, die ausgehend von Si‐haltigen, schweren Analoga von Alkenen gebildet werden, ist wichtig für ihre Anwendung in der radikalischen Polymerisation. Sterische und elektronische Substituenteneffekte in Phosphasilenen stabilisieren nicht nur die Si=P‐Doppelbindung, sondern beeinflussen auch die Struktur und Natur der gebildeten Radikale. Wir berichten hier über Untersuchungen an Phosphasilen‐abgeleiteten Radikalen mit Mes‐, Tip‐, Dur‐ und NMe2‐Substituenten am P‐Atom mithilfe von Myonenspinspektroskopie und DFT‐Rechnungen. Die Addition von Myonium (einem leichten Isotop von Wasserstoff) an Phosphasilene zeigt, dass a) das Elektronendonor‐NMe2‐ und das sperrigste Tip‐substituierte Phosphasilen mehrere myonierte Radikale mit unterschiedlichen Rotamer‐Konformationen bilden; b) das sperrige Dur‐substituierte Phosphasilen zwei Radikale (Si‐ und P‐zentriert) bildet; und c) Mes‐substituiertes Phosphasilen hauptsächlich eine Radikalspezies am P‐Zentrum bildet. Diese signifikanten Unterschiede rühren von einem intramolekularen Substituenteneffekt her.

Lithium ion batteries are complex systems with multiple components that can be optimized to obtain desired performance capability. These components include electrolyte salts, solvents, and additives, as well as electrode active materials and coatings. Rational optimization of battery components requires an understanding of the fundamental science driving the observed performance. Silatronix ® has developed a suite of analytical tools and methods using a combination of full format batteries, lab R&D cells, and model systems to construct a complete understanding of the battery from the cell level performance to the fundamental chemistry. This process includes the recovery and analysis of all parts of a full format pouch cell, including liquid electrolyte, generated gas, and electrode surface layers (Fig. 1). Using this process, Silatronix ® has evaluated several battery components, including organosilicon solvents for Li-ion electrolytes, to acquire a comprehensive picture of how these components provide observed performance benefits. For example, OS3 ® , a novel organosilicon chemistry that merges a silane with a Li + coordinating nitrile functionality, has provided multiple performance benefits in various advanced Li-ion chemistries. Key experimental results include improved high temperature cycling stability in full format graphite/NMC622 pouch cells with 1%, 2%, or 3% OS3 ® (Fig. 2a), and using a model system of electrolyte in NMR tubes, we show that enhanced thermal stability of the bulk electrolyte results from HF scavenging and LiPF 6 salt stabilization when 2-16% OS3 ® is present (Fig. 2b). Reduction of gas generation during high temperature testing in pouch cells with a commercial Si-based anode is also shown with 2% OS3 ® (Fig. 2c), and gas product identification and quantification is determined by GC-TCD for mechanistic analyses. In addition, OS materials change the reactivity of other electrolyte components, particularly at the electrolyte/electrode interfaces that govern critical performance attributes in Li-ion cells such as gas generation and interfacial impedance. These key performance benefits serve to enable several next generation battery chemistries, including a strong synergy with Si-based anodes. Figure 1

Cyclic voltammograms of four spiro-bifluorenes involving C (I), Si (II), Ge (III) and Sn (IV) as the central atom were recorded in acetonitrile-dichloromethane. Each substrate afforded one irreversible oxidation wave (between 1.7 to 1.9 V, vs. Ag/AgCl) and one irreversible reduction wave between -2.0 to -2.3 V (except for the Ge derivative III that showed a second irreversible reduction wave). Controlled potential anodic oxidation was executed for II-IV on a Pt anode. Surprisingly, each one of the substrates behaved differently: II yielded biphenyl (92 %) as the major product; III afforded moderate yields of a germafluorene dimer containing Ge-Ge bond (35 %) and 1,3,5-triphenylbenzene 10 (22 %), and IV formed the aromatic derivative 10 as the major product (76 %). In all cases, chlorinated products were formed too. A plausible mechanism for the formation of the variety of products is suggested.

The authors report on 7 Li, 19 F, and 1 H pulsed field gradient NMR measurements of 26 organosilyl nitrile solvent-based electrolytes of either lithium bis(trifluorosulfonyl)imide (LiTFSI) or lithium hexafluorophosphate. Lithium transport numbers (as high as 0.50) were measured and are highest in the LiTFSI electrolytes. The authors also report on solvent blend electrolytes of fluoroorganosilyl (FOS) nitrile solvent mixed with ethylene carbonate (EC) and diethyl carbonate. Solvent diffusion measurements on an electrolyte with 6% FOS suggest both the FOS and EC solvate the lithium cation. By comparing lithium transport and transference numbers, The authors find less ion pairing in FOS nitrile carbonate blend electrolytes and difluoroorganosilyl nitrile electrolytes.

Increasing fluorination of organosilyl nitrile solvents improves ionic conductivities of lithium salt electrolytes, resulting from higher values of salt dissociation. Ionic conductivities at 298 K range from 1.5 to 3.2 mS/cm for LiPF6 salt concentrations at 0.6 or 0.7 M. The authors also report on solvent blend electrolytes where the fluoroorganosilyl (FOS) nitrile solvent is mixed with ethylene carbonate and diethyl carbonate. Ionic conductivities of the FOS solvent/carbonate blend electrolytes increase achieving ionic conductivities at 298 K of 5.5–6.3 mS/cm and salt dissociation values ranging from 0.42 to 0.45. Salt dissociation generally decreases with increasing temperature.

Muonium (Mu), an H atom analogue, is employed to probe the addition of free radicals to the P=C bond of a phosphaalkene. Specifically, two unprecedented muoniated free radicals, MesP. -CMu(Me)2 (1 a, minor product) and MesPMu-C. Me2 (1 b, major product), were detected by muon spin spectroscopy (μSR) when a solution of MesP=CMe2 (1: Mes=2,4,6-trimethylphenyl) was exposed to a beam of positive muons (μ+ ). The μ+ serves as a source of Mu (that is, Mu=μ+ +e- ). To confirm the identity of the major product 1 b, its spectral features were compared to its isotopologue, MesPH-C. (Me)CH2 Mu (2 a). Conveniently, 2 a is the sole product of the reaction of MesPH(CMe=CH2 ) (2) with Mu. For all observed radicals, muon, proton, and phosphorus hyperfine coupling constants were determined by μSR and compared to DFT-calculated values.

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

There are many chronic diseases related with inflammation. The chronic inflammation can produce other problems as cancer. Therefore, it is necessary to design drugs with better anti-inflammatory activity than those in the clinic. Likewise, these could be used in chronic treatments with minimum adverse effects. The amide or ester functionality in combination with the insertion of a silyl alkyl moiety is able to improve some drug properties. In this context, the evaluation of a group of silicon containing ibuprofen derivatives (SCIDs) as antioxidants and anti-inflammatory agents is reported. Antioxidant activity was evaluated by the 2,2-Diphenyl-1-picrylhydrazyl (DPPH⨪), 2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonic) acid (ABTS•+) and the Fe(II) chelating ability methods. The anti-inflammatory activity was determined by using the carrageenan induced rat paw edema. The gastrotoxic profile of the SCIDs that displayed significant anti-inflammatory activity was determined by the indomethacin induced ulceration method. The SCIDs performed better than ibuprofen as chelating agents for Fe(II) and as scavengers for the free radicals DPPH• and ABTS•+. On the anti-inflammatory test, compound 4a inhibited the edema up to 87%, while 4d & 10b achieved significant inflammation inhibition at a lower effective dose 50 (ED50) than ibuprofen´s. None of the SCIDs endowed with anti-inflammatory activity, showed significant gastrotoxic effects with respect to those displayed by ibuprofen. Based on the experimental results and aided by the theoretical docking approach, it was possible to rationalize how the SCIDs may bind to cyclooxygenase isoforms and helped to explain their reduced gastrotoxicity. The evaluated effects were improved in SCIDs with respect to ibuprofen.

Oxidative stress-induced platelet apoptosis is one among the many causes for the development and progression of many disorders like cardiovascular diseases, arthritis, Alzheimer's disease and many chronic inflammatory responses. Many studies have demonstrated the less optimal effect of N-acetyl cysteine (NAC) in oxidative stress-induced cellular damage. This could be due to its less lipophilicity which makes it difficult to enter the cellular membrane. Therefore in the present study, lipophilic sila-amide derivatives (6a and 6b) synthesized through the reaction of NAC with 3-Aminopropyltrimethylsilane and aminomethyltrimethylsilane were used to determine their protective property against oxidative stress-induced platelet apoptosis. At a concentration of 10 µM, compound 6a and 6b were able to significantly inhibit Rotenone/H2O2 induced platelet apoptotic markers like reactive oxygen species, intracellular calcium level, mitochondrial membrane potential, cytochrome c release from mitochondrial to the cytosol, caspase-9 and -3 activity and phosphatidylserine externalization. Therefore, the compounds can be extrapolated as therapeutic agents to protect platelets from oxidative stress-induced platelet apoptosis and its associated complications.

Herein, we present a brief overview of the recent developments in the field of photoluminescent cyclosiloxanes, with a special focus on the synthesis and unique photophysical properties of newly reported silole-based cyclosiloxanes with pronounced aggregation-induced emission (AIE) behaviour. Comparisons of their photophysical data as well as the results of computational studies of various types of silole-based cyclosiloxanes are presented and their potential applications are briefly discussed.

Organosilicon (OS) electrolytes have been developed as a viable alternative to conventional carbonate electrolytes for lithium ion batteries. A recent trend in the Li-ion industry toward adoption of new materials, including electrolytes, is driven by the desire to deploy larger capacity batteries under broader operating conditions. In addition, the development of 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. This novel organosilicon chemistry involves the merging of a silane with a lithium coordinating functionality. This combination results in solvents comprised of low molecular-weight molecules and having unique properties including high thermal stability, high flash point, low vapor pressure and relatively low viscosities. Recently, Silatronix has developed an entirely new class of OS molecules to provide new (patent pending) “Gen-3” solvents whose thermal, chemical, and electrochemical properties greatly surpass those of the earlier suite of OS compounds. Multiple structural variations from the “Gen-3” OS family showcase greatly enhanced stability and performance attributes. Specific examples of performance improvement include higher conductivity and lower viscosity while concomitantly providing superior thermal stability with LiPF6 and reduced gassing. In this work, we demonstrate the superior stability and performance attributes of the “Gen-3” family of molecules. For this we have evaluated the physical properties, thermal and electrochemical stability, and performance in coin and pouch cells across a wide temperature range with a variety of electrode materials. This work focuses on exploring the fundamental mechanisms underlying the enhanced stability, including a unique solvation sphere which provides salt stabilization and enhances the stability of all electrolyte components.

AbstractN‐Heterocyclic carbenes (NHC's) are known to serve as efficient substrates for the stabilization of various transient species possessing low‐valent Group 14 elements and for the generation of double E=C bonds. Herein, we report that the thermal tri‐ and tetramerizations of pyridoannulated silylene 1 lead to the formation of remarkably stable silenes 2 and 3 featuring zwitterionic distribution of electron density. Co‐oligomerization of 1 and its germanium analogue gives a related tetrameric product 4 containing low‐valent germanium atom stabilized by binding with the partial carbene‐character C atom. Bonding situations in 2–4 are best described as silene or germene with the significant zwitterionic distribution of electron density. The singlet diradical electronic state of 2 is 10 kcal mol−1 higher than the ground state configuration.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.