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Fluoroethylene Carbonate as an Additive for γ-Butyrolactone Based Electrolytes

2013; Institute of Physics; Volume: 160; Issue: 9 Linguagem: Inglês

10.1149/2.009309jes

1945-7111

Johannes Kasnatscheew, Raphael Schmitz, Ralf Wagner, Martin Winter, René Schmitz,

Advanced Battery Technologies Research

Compared to the actual state of the art electrolyte (SOTA) for Lithium-ion batteries (LIBs), a novel electrolyte with better safety and lower costs and at the same time equal electrochemical performance was developed and investigated in this work. This electrolyte consists of a mixture of γ-Butyrolactone (GBL) as a solvent with fluoroethylene carbonate (FEC) as solid electrolyte interphase (SEI) additive and lithium tetrafluro borate (LiBF4) as electrolyte salt. Raman spectroscopy measurements indicated that the salt is completely dissociated by the solvent GBL which is the reason for the enhanced ionic conductivity compared to the SOTA electrolyte. Cyclic voltammetry with a T44 graphite electrode revealed the positive influence of the SEI additive FEC. The addition of FEC (1% by wt) enabled fully reversible de-/ intercalation of lithium ions into graphite. Furthermore, 1 M LiBF4 in GBL + FEC (1% by wt) improved the coulombic efficiency of T44 graphite in the first cycle of constant current cycling experiments and in addition, no capacity fading was observed after 50 cycles. On NCM electrodes a stable cycling was observed as well, obtaining similar performance compared to the SOTA electrolyte, even at an increased cutoff potential of 4.6 V vs. Li/Li+.