A Highly Soluble Redox Shuttle with Superior Rate Performance in Overcharge Protection. Issue 1740 (2nd March 2015)

• Record Type: Journal Article
• Authors: Odom, Susan A.; Kaur, Aman; Ergun, Selin; Elliott, Corrine F.; Casselman, Matthew D.
• Editors: Cresce, A.
• Is Part Of: MRS proceedings. Issue 1740:(2015)
• Publication Date: 2015-03-02
• Subjects: energy storage, -- organic, -- chemical reaction; Electrical engineering -- Congresses; Physics -- Congresses; Materials -- Research -- Congresses; Materials science -- Congresses; 620.11
• DOI: 10.1557/opl.2015.204
• Languages: English
• ISSNs: 0272-9172

Abstract

ABSTRACT: The demand for a stable and compatible redox shuttles for use in lithium-ion batteries has prompted us to explore strategies to tune and improve the properties of redox shuttles. We have studied over 50 new diarylamine derivatives synthesized in our laboratory including one compound in which we introduced trifluoromethyl groups (–CF3 ) at the positions para to the nitrogen atom in N -ethylphenothiazine (EPT). The high electronegativity of the CF3 group raises the oxidation potential, and its incorporation also significantly increases solubility in battery electrolyte. Here we report 3, 7-bis(trifluoromethyl)- N -ethylphenothiazine (BCF3EPT) as a new redox shuttle, which we have observed to have the highest reported solubility in battery electrolyte of all redox shuttles that maintain extended overcharge performance. We have compared its performance with 1, 3-di- tert -butyl-2, 5-dimethoxybenzene (DBB), EPT, and other robust redox shuttles. In our hands, overcharge cycling of BCF3EPT far surpasses any reported redox shuttle, and – because it can be dissolved at higher concentrations – it tolerates faster charging rates than both DBB and EPT.