Investigation of Redox Shuttle Generation in LFP/Graphite and NMC811/Graphite Cells. Issue 4 (1st April 2022)

• Record Type: Journal Article
• Authors: Boulanger, Thomas; Eldesoky, Ahmed; Buechele, Sebastian; Taskovic, Tina; Azam, Saad; Aiken, Connor; Logan, Eric; Metzger, Michael
• Is Part Of: Journal of the Electrochemical Society. Volume 169:Issue 4(2022)
• Publication Date: 2022-04-01
• Subjects: Electrochemistry -- Periodicals; 541.3705
• DOI: 10.1149/1945-7111/ac62c6
• Languages: English
• ISSNs: 0013-4651

Abstract

Abstract : Unwanted redox shuttles can lead to self-discharge and inefficiency in lithium-ion cells. This study investigates the generation of a redox shuttle in LFP/graphite and NMC811/graphite pouch cells with common alkyl carbonate electrolyte. Visual inspection of the electrolyte extracted after formation at temperatures between 25 and 70 °C reveals strong discoloration. Such extracted electrolytes with intense red and brown color show relatively large shuttling currents in Al/Li coin cells. Two weight percent of vinylene carbonate is effective at preventing the redox shuttle generation as indicated by the absence of electrolyte discoloration and shuttling current. Ultra-high precision coulometry demonstrates that the presence of the shuttle molecule during cycling of LFP/graphite and NMC811/graphite pouch cells leads to significant charge endpoint capacity slippage and coulombic inefficiency. A brief constant voltage hold at 4.2 V can eliminate the shuttle molecule.