Open AccessInvestigation of Redox Shuttle Generation in LFP/Graphite and NMC811/Graphite Cells
Author(s) -
Thomas Boulanger,
Ahmed Eldesoky,
Sebastian Buechele,
Tina Taskovic,
Saad Azam,
Connor Aiken,
Eric Logan,
Michael Metzger
Publication year - 2022
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/ac62c6
Subject(s) - electrolyte , graphite , redox , chemistry , lithium (medication) , materials science , chemical engineering , inorganic chemistry , electrode , organic chemistry , medicine , engineering , endocrinology
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.