PDF Publication Title:
Text from PDF Page: 039
(DIOX) and 1,2-dimethoxyethane (DME), usually in equal volumetric proportions. A whole family of high molecular weight ethers, such as diethylene glycol dimethylether (diglyme, DEGDME), tetraethylene glycol dimethylether (tetraglyme, TEGDME), polyethylene glycol dimethylether (PEGDME), has also been extensively studied. Several systematic investigations were conducted on single or binary electrolyte systems, in order to find the most optimal composition158,159,160. Other solvents were also considered, such as sulfolanes161,162,163,164, tetrahydrofuran (THF)165, toluene166. Apart from liquid electrolytes, other alternative solvents were proposed, i.e. gel polymer electrolytes167, solid polymer electrolytes168, ionic liquids169,170 or liquid electrolytes with high salt concentration171, mostly targeting for polysulfide shuttle mitigation. Due to the different properties of electrolyte solvents, not only the solubility of sulfur may vary, but also behavior of polysulfide species may differ. Indeed, UV-Vis spectroscopy tests27,172 and rotating-ring disk electrode (RRDE) studies173 performed on two systems with both sulfolane and ether-based electrolytes, showed different polysulfides behaviors. Concerning the choice of Li salt, it seems that its effect was not studied a lot for Li/S system174, even if well-known to impact electrolyte conductivity, passivation film on lithium, etc. The most popular salt is LiTFSI (lithium bis(trifluoromethanesulfonyl)imide), used in the concentration of 1M. Indeed, this salt presents high conduction properties, high thermal, chemical and electrochemical stabilities, and substantially lower sensitivity towards moisture (no hydrolysis) as compared with LiPF6 (most common salt used in Li-ion batteries)175. In the case of Li/S system, the high cut-off potential value is 3.0 V vs. Li+/Li (maximum 4.0 V in case of the initial cycle of Li2S), thus no corrosion of the aluminum current collector is expected. On the contrary, the presence of LiTFSI in carbonate based electrolyte is responsible for parasitic current at potential above 4.0 V vs. Li+/Li, which is attributed to aluminum corrosion176. The most popular approaches conducted in terms of electrolyte improvement are related with the use of additives. The commonly known one is lithium nitrate (LiNO3), used to stabilize the metallic lithium surface as initially studied by Aurbach et al.47, and followed by extensive reports of Zhang177,178. LiNO3 proves to be highly efficient to suppress the shuttle mechanism due to efficient passivation of the lithium surface, and drastic improvements of coulombic efficiency are reported. However, beneficial lithium passivation is also accompanied with irreversible reduction of LiNO3 at the carbon surface in the positive electrode, when discharging to the potentials below 1.6 V177. Its beneficial effects may also be decreased during prolonged cycling due to the additive consumption. Introduction of soluble lithium polysulfides into the electrolyte is also reported. Lee et al.179 and Xu et al.180 added polysulfides as an electrolyte buffer to prevent dissolution of positive electrode actives material. However, it is really likely that these already dissolved polysulfides participate to the electrochemical process, i.e. resulting in an extra-capacity (not related to the positive electrode). Moreover, if added in a sufficient concentration, polysulfides may also be Chapter 1: Literature review 35PDF Image | Accumulateur Lithium Soufre
PDF Search Title:
Accumulateur Lithium SoufreOriginal File Name Searched:
WALUS_2015_archivage.pdfDIY PDF Search: Google It | Yahoo | Bing
Sulfur Deposition on Carbon Nanofibers using Supercritical CO2 Sulfur Deposition on Carbon Nanofibers using Supercritical CO2. Gamma sulfur also known as mother of pearl sulfur and nacreous sulfur... More Info
CO2 Organic Rankine Cycle Experimenter Platform The supercritical CO2 phase change system is both a heat pump and organic rankine cycle which can be used for those purposes and as a supercritical extractor for advanced subcritical and supercritical extraction technology. Uses include producing nanoparticles, precious metal CO2 extraction, lithium battery recycling, and other applications... More Info
CONTACT TEL: 608-238-6001 Email: greg@infinityturbine.com (Standard Web Page)