Open AccessSynergy between LiNO3 and Tetraglyme-Sulfone Dual-Solvent Electrolyte Solutions in Li-O2 Batteries
Author(s) -
Yoshiya Hayashi,
Minoru Sohmiya,
Hiromitsu Otsuka,
Kazushi Ito,
Yoshimi Kubo,
Tatsuo Horiba,
Morihiro Saito
Publication year - 2020
Publication title -
journal of the electrochemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.258
H-Index - 271
eISSN - 1945-7111
pISSN - 0013-4651
DOI - 10.1149/1945-7111/abd04a
Subject(s) - sulfone , electrolyte , chemistry , dissociation (chemistry) , solvation , solvent , ionic liquid , inorganic chemistry , electrode , polymer chemistry , organic chemistry , catalysis
LiNO 3 has been widely studied as a redox mediator to reduce positive electrode overvoltage during charging of lithium/air (O 2 ) batteries. LiNO 3 has a bifunctional effect as a redox mediator for the positive electrode and as a surface modifier for the lithium negative electrode. The dissociation of LiNO 3 electrolyte salt was enhanced by using a mixed solvent of tetraglyme and a sulfone with a high dielectric constant. This extended the charging voltage plateau because the mixed solvent enhanced the oxidation of NO 2 − into NO 2 in the 1.0 M LiNO 3 electrolyte solution. The viscosities of the sulfone-containing electrolyte solutions decreased and their ionic conductivities increased as the temperature increased. Therefore, Walden plots for the electrolyte solutions containing sulfones were parallel to the ideal line, meaning that the dissociation of LiNO 3 was unaffected by temperature due to the strong solvation of ethyl methyl sulfone and tetramethylene sulfone to Li + ions. Consequently, the sulfone-containing electrolyte solutions delivered better charging performance than an electrolyte solution of simple tetraglyme at 50 °C.