Effects of Li ion-solvent interaction on ionic transport and electrochemical properties in highly concentrated cyclic carbonate electrolytes

ABSTRACT: In recent research, the importance of electrolytes with high Li+ transference number (tLi) and ionic conductivity (σion) has been emphasized to realize rapid charge for Li secondary batteries. Simultaneously fulfilling high tLi and σion is still unsolved in liquid electrolytes; however, hi...

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Autores principales:	Keisuke Shigenobu, Taku Sudoh, Mayu Tabuchi, Seiji Tsuzuki, Wataru Shinoda, Kaoru Dokko, Masayoshi Watanabe, Kazuhide Ueno
Formato:	article
Lenguaje:	EN
Publicado:	Elsevier 2021
Materias:	Highly concentrated electrolyte Lithium transference number Ionic conductivity Fluoroethylene carbonate Weakly coordinating property. Materials of engineering and construction. Mechanics of materials TA401-492 Chemistry QD1-999
Acceso en línea:	https://doaj.org/article/8784df70e7184a4485d72a333804637c
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spelling	oai:doaj.org-article:8784df70e7184a4485d72a333804637c2021-12-02T05:03:37ZEffects of Li ion-solvent interaction on ionic transport and electrochemical properties in highly concentrated cyclic carbonate electrolytes2590-159110.1016/j.nocx.2021.100071https://doaj.org/article/8784df70e7184a4485d72a333804637c2021-09-01T00:00:00Zhttp://www.sciencedirect.com/science/article/pii/S2590159121000121https://doaj.org/toc/2590-1591ABSTRACT: In recent research, the importance of electrolytes with high Li+ transference number (tLi) and ionic conductivity (σion) has been emphasized to realize rapid charge for Li secondary batteries. Simultaneously fulfilling high tLi and σion is still unsolved in liquid electrolytes; however, highly concentrated electrolytes (HCEs) of weakly coordinating solvents and Li salts will be promising for addressing this challenge. This idea is inspired by a recent study by Angell et al. on superprotonic ionic liquids comprising a weak Brønsted base and a superacid; highly labile and exchangeable H+ can be formed between significantly weak proton accepting sites. Here, we studied weakly coordinating fluoroethylene carbonate (FEC)-based electrolytes with lithium bis(fluorosulfonyl)amide (Li[FSA]) and compared with ethylene carbonate (EC)-based electrolytes. Experimental and computational studies indicated that solvent and ion exchange is more pronounced in the FEC-based HCE, resulting in higher tLiPP (0.73) and ionic conductivity (1.02 mS cm−1) compared to those of the EC-based HCE (tLiPP= 0.53 and σion= 0.84 mS cm−1). However, the FEC-based HCE exhibited lower electrochemical stability due to the intrinsically lower reductive stability of FEC and the oxidative decomposition of the liberated solvent in the HCE. Despite the superior transport properties, the Li/LiCoO2 cell with the FEC-based electrolyte showed lower discharge capacities and lower Coulombic efficiencies at higher current densities due to side reactions of the electrolyte. This study demonstrates that weak Li-solvent interactions can simultaneously enhance tLi and σion of HCEs, but they have the potential to sacrifice the electrochemical stability.Keisuke ShigenobuTaku SudohMayu TabuchiSeiji TsuzukiWataru ShinodaKaoru DokkoMasayoshi WatanabeKazuhide UenoElsevierarticleHighly concentrated electrolyteLithium transference numberIonic conductivityFluoroethylene carbonateWeakly coordinating property.Materials of engineering and construction. Mechanics of materialsTA401-492ChemistryQD1-999ENJournal of Non-Crystalline Solids: X, Vol 11, Iss , Pp 100071- (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Highly concentrated electrolyte Lithium transference number Ionic conductivity Fluoroethylene carbonate Weakly coordinating property. Materials of engineering and construction. Mechanics of materials TA401-492 Chemistry QD1-999
spellingShingle	Highly concentrated electrolyte Lithium transference number Ionic conductivity Fluoroethylene carbonate Weakly coordinating property. Materials of engineering and construction. Mechanics of materials TA401-492 Chemistry QD1-999 Keisuke Shigenobu Taku Sudoh Mayu Tabuchi Seiji Tsuzuki Wataru Shinoda Kaoru Dokko Masayoshi Watanabe Kazuhide Ueno Effects of Li ion-solvent interaction on ionic transport and electrochemical properties in highly concentrated cyclic carbonate electrolytes
description	ABSTRACT: In recent research, the importance of electrolytes with high Li+ transference number (tLi) and ionic conductivity (σion) has been emphasized to realize rapid charge for Li secondary batteries. Simultaneously fulfilling high tLi and σion is still unsolved in liquid electrolytes; however, highly concentrated electrolytes (HCEs) of weakly coordinating solvents and Li salts will be promising for addressing this challenge. This idea is inspired by a recent study by Angell et al. on superprotonic ionic liquids comprising a weak Brønsted base and a superacid; highly labile and exchangeable H+ can be formed between significantly weak proton accepting sites. Here, we studied weakly coordinating fluoroethylene carbonate (FEC)-based electrolytes with lithium bis(fluorosulfonyl)amide (Li[FSA]) and compared with ethylene carbonate (EC)-based electrolytes. Experimental and computational studies indicated that solvent and ion exchange is more pronounced in the FEC-based HCE, resulting in higher tLiPP (0.73) and ionic conductivity (1.02 mS cm−1) compared to those of the EC-based HCE (tLiPP= 0.53 and σion= 0.84 mS cm−1). However, the FEC-based HCE exhibited lower electrochemical stability due to the intrinsically lower reductive stability of FEC and the oxidative decomposition of the liberated solvent in the HCE. Despite the superior transport properties, the Li/LiCoO2 cell with the FEC-based electrolyte showed lower discharge capacities and lower Coulombic efficiencies at higher current densities due to side reactions of the electrolyte. This study demonstrates that weak Li-solvent interactions can simultaneously enhance tLi and σion of HCEs, but they have the potential to sacrifice the electrochemical stability.
format	article
author	Keisuke Shigenobu Taku Sudoh Mayu Tabuchi Seiji Tsuzuki Wataru Shinoda Kaoru Dokko Masayoshi Watanabe Kazuhide Ueno
author_facet	Keisuke Shigenobu Taku Sudoh Mayu Tabuchi Seiji Tsuzuki Wataru Shinoda Kaoru Dokko Masayoshi Watanabe Kazuhide Ueno
author_sort	Keisuke Shigenobu
title	Effects of Li ion-solvent interaction on ionic transport and electrochemical properties in highly concentrated cyclic carbonate electrolytes
title_short	Effects of Li ion-solvent interaction on ionic transport and electrochemical properties in highly concentrated cyclic carbonate electrolytes
title_full	Effects of Li ion-solvent interaction on ionic transport and electrochemical properties in highly concentrated cyclic carbonate electrolytes
title_fullStr	Effects of Li ion-solvent interaction on ionic transport and electrochemical properties in highly concentrated cyclic carbonate electrolytes
title_full_unstemmed	Effects of Li ion-solvent interaction on ionic transport and electrochemical properties in highly concentrated cyclic carbonate electrolytes
title_sort	effects of li ion-solvent interaction on ionic transport and electrochemical properties in highly concentrated cyclic carbonate electrolytes
publisher	Elsevier
publishDate	2021
url	https://doaj.org/article/8784df70e7184a4485d72a333804637c
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Effects of Li ion-solvent interaction on ionic transport and electrochemical properties in highly concentrated cyclic carbonate electrolytes

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