Reversible Graphite Anode Cycling with PC-Based Electrolytes Enabled by Added Sulfur Trioxide Complexes

Pyridine sulfur trioxide (PyrSO3), trimethyl amine sulfur trioxide (Me3NSO3), and triethyl amine sulfur trioxide (Et3NSO3) complexes have been investigated as electrolyte additives for lithium ion batteries. Incorporation of 0.5 to 2.0% of the SO3 complexes into a PC/EMC (1:1 v/v) 1 M LiPF6 baseline electrolyte affords reversible cycling of graphite anodes confirming generation of a stable Solid Electrolyte Interphase (SEI). Good cycling performance is observed for graphite/LiNi0.5Mn1.5O4 cells cycled to high potential (4.8 V vs Li) containing PC based electrolyte with added SO3 complexes. Ex-situ surface analysis via X-ray Photoelectron Spectroscopy (XPS) of the anodes reveals SO3 complex reduction on the surface of the graphite anode generates a sulfur-based SEI containing sulfites, sulfide, and sulfate species. The presence of the sulfur containing species is likely critical for the stability of the SEI. Ex-situ XPS analyses of the LiNi0.5Mn1.5O4 cathodes suggest that reaction of Me3NSO3 or Et3NSO3 complexes at high potential result in the generation of a stable passivation layer which affords good capacity retention and coulombic efficiency

Improved Performance of High Voltage Graphite/LiNi\u3csub\u3e0.5\u3c/sub\u3eMn\u3csub\u3e1.5\u3c/sub\u3eO\u3csub\u3e4\u3c/sub\u3e Batteries with Added Lithium Tetramethyl Borate

Lithium tetramethyl borate (LTMB, LiB(OCH3)4) has been prepared and investigated as a novel cathode film forming additive to improve the performance of LiNi0.5Mn1.5O4 cathodes cycled to high potential (4.25-4.8 V). Addition of LTMB to 1.2 M LiPF6 in EC/EMC (3/7, v/v) improves the capacity retention of graphite/LiNi0.5Mn1.5O4 cells cycled at 55°C. The added LTMB is sacrificially oxidized on the surface of the cathode during the first charging cycle. Ex-situ surface analysis of the LiNi0.5Mn1.5O4 by X-ray photoelectron spectroscopy (XPS) reveals the presence of a borate based passivating layer which appears to inhibit electrolyte oxidation on the cathode surface

Improved Performance of High Voltage Graphite/LiNi\u3csub\u3e0.5\u3c/sub\u3eMn\u3csub\u3e1.5\u3c/sub\u3eO\u3csub\u3e4\u3c/sub\u3e Batteries with Added Lithium Tetramethyl Borate

Lithium tetramethyl borate (LTMB, LiB(OCH3)4) has been prepared and investigated as a novel cathode film forming additive to improve the performance of LiNi0.5Mn1.5O4 cathodes cycled to high potential (4.25-4.8 V). Addition of LTMB to 1.2 M LiPF6 in EC/EMC (3/7, v/v) improves the capacity retention of graphite/LiNi0.5Mn1.5O4 cells cycled at 55°C. The added LTMB is sacrificially oxidized on the surface of the cathode during the first charging cycle. Ex-situ surface analysis of the LiNi0.5Mn1.5O4 by X-ray photoelectron spectroscopy (XPS) reveals the presence of a borate based passivating layer which appears to inhibit electrolyte oxidation on the cathode surface

Improving the Performance at Elevated Temperature of High Voltage Graphite/LiNi\u3csub\u3e0.5\u3c/sub\u3eMn\u3csub\u3e1.5\u3c/sub\u3eO\u3csub\u3e4\u3c/sub\u3e Cells with Added Lithium Catechol Dimethyl Borate

Performance of LiNi0.5Mn1.5O4/graphite cells cycled to 4.8 V at 55°C with the 1.2 M LiPF6 in EC/EMC (3/7, STD electrolyte) with and without added lithium catechol dimethyl borate (LiCDMB) has been investigated. The incorporation of 0.5 wt% LiCDMB to the STD electrolyte results in an improved capacity retention and coulombic efficiency upon cycling at 55°C. Ex-situ analysis of the electrode surfaces via a combination of SEM, TEM, and XPS reveals that oxidation of LiCDMB at high potential results in the deposition of a passivation layer on the electrode surface, preventing transition metal ion dissolution from the cathode and subsequent deposition on the anode. NMR investigations of the bulk electrolyte stored at 85°C reveals that added LiCDMB prevents the thermal decomposition of LiPF6

Title no available

Les accumulateurs LiNi0.4Mn1.6O4 (LNMO)/Li4Ti5O12 (LTO), permettent d’atteindre théoriquement les densités de puissance et d’énergie fournissant une autonomie suffisante aux véhicules électriques. Cependant, deux problèmes majeurs liés à LNMO limitent leurs performances : l’oxydation prononcée des électrolytes à base de carbonates d’alkyles et la dissolution d’ions de métaux de transition (Mn2+, Ni2+). Les formulations à base de carbonate d’éthylène (EC) ont une aptitude à former des films polymères couvrant la matière active. Les cyclages galvanostatiques, faisant suite ou non à un stockage, confirment la supériorité de ces électrolytes, conduisant à des pertes de capacité réduites de l’électrode LNMO. D’autre part, les sulfones sont des composés prometteurs pour une utilisation dans les batteries LNMO/LTO. L’emploi de cellules symétriques et asymétriques démontre que les sulfones sont non-réactives vis-à-vis des interfaces LNMO/électrolyte et LTO/électrolyte. Cependant, cette non-réactivité ne permet pas le dépôt de films polymères qui auraient permis de stopper la dissolution d’ions Mn2+ et Ni2+ à partir de l’électrode positive. Ceci résulte en des performances dégradées à 30°C des accumulateurs par rapport à ceux employant EC dans les électrolytes.LiNi0.4Mn1.6O4 (LNMO)/Li4Ti5O12 (LTO) accumulators should theoretically achieve the power and energy densities that provide sufficient autonomy to electric vehicles. However, two major issues related to the use of LNMO limit their performances: the pronounced oxidation of the alkylcarbonate-based electrolytes and the transition metal ion (Mn2+, Ni2+) dissolution. The ethylene carbonate (EC)-based formulations get an ability to form polymer-covering films onto the active material. The galvanostatic cycling tests, after storage or not, confirm the superiority of these electrolytes, leading to reduced capacity losses of the LNMO electrode. Furthermore, sulfones are promising compounds to be applied to LNMO/LTO batteries. The use of symmetric and asymmetric cells demonstrates that sulfones are non-reactive towards the LNMO/electrolyte and LTO/electrolyte interfaces. However, this non-reactivity does not allow the deposition of polymer films, which would have enabled to stop the Mn2+ and Ni2+ dissolution from the positive electrode. This results in degraded performances of batteries at 30°C compared to those using EC in electrolytes

La gestion du temps de consultation lors du stage chez le praticien (enquête auprès des résidents d'Aquitaine ayant effectué le stage entre novembre 2004 et mai 2006)

BORDEAUX2-BU Santé (330632101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

LiNi _0.4 Mn _1.6 O ₄ /electrolyte and carbon black/electrolyte high voltage interfaces: to evidence the chemical and electronic contributions of the solvent on the cathode-electrolyte interface formation

245th ECS Meeting May 26-May 30, 2024, San Francisco, USAInternational audienceSolvent and lithium salt decomposition products on LiNixMnyO4-type electrodes are known to be ROM, ROCO2M (M = Li, Ni, Mn), LiF, LixPFyOz, polycarbonates and polyethers. These compounds are chemically formed due to the high nucleophilic character of spinel oxide and LiPF6 decomposition. The high potentials (> 4.7 V vs. Li/Li+) may cause EC and PC polymerization, while DMC forms oligomers. The use of carbon black-based electrodes highlights electronic and, surprisingly, chemical contributions to the cathode-electrolyte interface. A comparison between EC/DMC (1:1 in weight) 1 M LiPF6 and PC/DMC (1:1 in weight) 1 M LiPF6 electrolytes for Li/carbon black-PVdF cells demonstrated a superior ability of the EC/DMC solution to form a well-covering passivation film via faradaic reactions thanks to a higher stability toward oxidation. Electrochemical cycling in Li/LiNi0.4Mn1.6O4 cells confirms this EC/DMC superiority when it comes to forming passivation films, in turn leading to reduced capacity losses and a higher Columbic efficiency