Lithium Imide Electrolytes with Two-Oxygen-Atom-Containing Cycloalkane Solvents for 4 V Lithium Metal Rechargeable Batteries

Abstract

Though much effort has been paid for lithium metal rechargeable batteries with lithium metal as anode in the past decades, 1-6 its commercial application is not yet realized. This has been attributed to the interface reaction of freshly deposited lithium with inorganic and organic species in the electrolytes, which results in low lithium cycling efficiency, deleterious dendritic morphology of deposited lithium surface, and safety concern. Therefore, finding electrolytes with low reactivity with lithium metal is an important issue in the effort to realize the commercial application of lithium metal rechargeable batteries.So far, tetrahydrofuran (THF) and its alkyl derivative electrolytes with LiAsF 6 or LiClO 4 as solute was explored mainly to suppress the reaction of lithium anode with electrolytes. 11-17 1,3-Dioxolane (DOL) based electrolytes also received special attention due to high lithium cycling efficiency in this electrolyte. 18-21 Nevertheless, the poor anodic stability of THF-based solvents and DOL solvent led to the application of these electrolytes only in 3 V lithium metal rechargeable batteries. 11,13,14 The toxicity of LiAsF 6 and the safety problems of LiClO 4 also limited the practical application of these electrolytes.In recent work, we developed 1 mol/dm 3 LiN(SO 2 C 2 F 5 ) 2 /EC ϩ tetrahydropyran (THP) (5:5) electrolyte. [22][23][24][25][26] This electrolyte was found to have many advantages, such as a high lithium cycling efficiency of >99%, good oxidation stability, satisfactory boiling point, and promising thermal stability. The Li/LiMn 2 O 4 coin cell with this electrolyte also gave excellent cycling performance. Furthermore, scanning electron microscopy (SEM) observation showed that the deposited lithium in this electrolyte had fine particle morphology rather than dendritic morphology. Other groups have also studied the use of lithium imide salts for lithium rechargeable batteries. 27-30 Naoi et al. reported the good surface morphology of deposited lithium and high lithium cycling efficiency in LiN(SO 2 C 2 F 5 ) 2 electrolytes. 31 The main problems inherent in the practical application of 1 mol/dm 3 LiN(SO 2 C 2 F 5 ) 2 /EC ϩ THP (5:5) electrolyte are poor lowtemperature performance (freezing point: 8ЊC) and low boiling point of THP solvent. To solve this problem, we studied LiN(SO 2 C 2 F 5 ) 2 electrolytes with DOL, 1,3-dioxane (DOX), 1,3-dioxepane (DOXP) and their alkyl derivatives as solvents in this work. ExperimentalElectrolyte preparation.- Table I lists the examined solutes and five-, six-, and seven-membered cycloalkane solvents with two oxygen atoms. These solvents were generally used with a purity of >99% after being purified by distillation. Lithium bistrifluoromethylsulfonyl imide (LiN(SO 2 CF 3 ) 2 ) and LiN(SO 2 C 2 F 5 ) 2 solutes were dried at 130ЊC and under vacuum for 24 h, while LiPF 6 solute was used as received due to its high purity (battery grade). The preparation of electrolytes was performed in an argon glove box. The water content in the resultant electrolytes...

Metalltriflimidate sind bessere Katalysatoren für die organische Synthese als Metalltriflate – der Effekt eines stark delokalisierten Gegenions

“…[49][50][51][52][53] Unter den Metalltriflimidaten fand nur Lithiumtriflimidat, LiNTf 2 , ein unbedenklicher Ersatz für Lithiumperchlorat, eine wichtige industrielle Anwendung, als Elektrolyt in Batterien für Elektrofahrzeuge. [54][55][56] Dieser Aufsatz konzentriert sich auf die Synthese von Metalltriflimidaten und ihre wichtigsten Anwendungen in katalytischen organischen Umwandlungen bis März 2010. Metall-bis(trifluormethansulfonyl)imidate sind unseres Wissens, außer für Lithium und Silber, nicht kommerziell erhältlich.…”

“…Metall-bis(trifluormethansulfonyl)imidate sind unseres Wissens, außer für Lithium und Silber, nicht kommerziell erhältlich. [57] Auf die Verwendung von LiNTf 2 als Elektrolyt in Lithiumbatterien [54][55][56] sowie sein elektrochemisches Verhalten [58] und die Anwendungen von organischen Triflimidatsalzen als ionische Flüssigkeiten [59][60][61] werden wir in unserem Aufsatz nicht eingehen.…”

Efficient Preparation of Anhydrous Metallic Triflates and Triflimides under Ultrasonic Activation

“…[1] Their catalytic efficiency, as compared to those of classical Lewis acids such as AlCl 3 or ZnCl 2 , has been highlighted by the possibility to work under low catalyst loading for high yields and selective processes, enabling in some cases to go from stoichiometric to catalytic reactions and in other cases to develop new original reactions.…”

“…[3,4] Classically, metallic triflates or triflimides can be prepared from metal oxides, [5] hydroxides, [6] carbonates, [7] or halides, [8] and triflic or triflimidic acid. These reactions are performed in water or in aqueous media and afford the corresponding hydrated salts.…”

“…Alternative preparations of anhydrous metallic triflates and triflimides solvated by organic solvent molecules have been reported by an electrochemical method [9] and an oxidative dissolution of metal powders in DMSO under O 2 . [10] In the specific case of Bi III , Bi(OTf) 3 has been prepared from BiPh 3 under anhydrous conditions. [11] The literature mentions only a few direct preparations of metallic triflates and triflimides by reaction of metals with solvents.…”