Effect of Substituting LiBF 4 for LiPF 6 in High Voltage Lithium-Ion Cells Containing Electrolyte Additives

Abstract

© The Author(s) 2016. Published by ECS. All rights reserved. This work evaluates the performance of LiBF4-containing electrolytes in lithium-ion cells charged to high voltages (>4.4 V) and explores the compatibility of LiBF4with additives known to improve the performance of LiPF6-based electrolytes. It was found that the benefit imparted by LiBF4is lost when cells are charged beyond 4.4V, at which point electrolyte oxidation causes gas evolution and impedance growth. In the case of LiBF4, impedance growth is shown to be due to increased charge transfer resistance at the negative electrode, indicating poor passivation of the negative electrode. Of the additives tested, only those containing prop-1-ene-1,3-sultone benefit cells with LiBF4electrolyte at high voltage.