Investigation of the Solid Electrolyte Interphase on MCMB and NG Electrodes in Lithium Tetrafluorooxalatophosphate [LiPF4C2O4] Based Electrolyte

Abstract

The performance of the novel lithium salt, lithium tetrafluorooxalatophopshate (LiPF 4 (C 2 O 4 )) has been investigated as electrolyte solution in carbonate solvents. Investigation of the performance of LiPF 4 (C 2 O 4 ) electrolytes in the presence of different types of anode materials, Mesocarbon Microbead (MCMB) graphite and Nature Graphite (NG), has uncovered a dependence of a first cycle shoulder at 1.75 V and irreversible capacity on the structure of the anodic graphite. Andoes with more irreversible capacity have a thicker anode solid electrolyte interphase (SEI) which is most likely caused by differences in the surface of the graphite. Appropriate choice of graphite leads to first cycle efficiencies which are very similar for LiPF 4 (C 2 O 4 ) and LiPF 6 electrolytes.

Electrolytes and Interphases in Li-Ion Batteries and Beyond

“…Instead of complete fluorine substitution as in TOP, Lucht and co-workers developed the phosphate anion where labile fluorines were only partially replaced by oxalato-chelates, that is, tetrafluorooxalatophosphate (TFOP, Table ). − In carbonate solvents, this salt demonstrated ion conductivity similar to that of LiPF 6 (∼8 mS/cm at ambient temperature), which is higher than LiBF 4 or LiBOB. The electrolytes based on it can support reversible Li + -intercalation chemistries on both graphitic anode and LiNi 0.8 Co 0.2 O 2 cathode, indicating necessary interphases were formed on both electrodes.…”

Molecular Dynamics Simulation Studies of the Structure of a Mixed Carbonate/LiPF6 Electrolyte near Graphite Surface as a Function of Electrode Potential

“…The interface between the electrolyte and the electrodes is central to the operation of lithium ion batteries. Reduction of the electrolyte at the anode surface and oxidation at the cathode surface result in decomposition products that comprise the solid electrolyte interface (SEI) layers that ultimately passivate the electrodes and protect the electrolyte from further decomposition . The structure of the SEI is believed to depend on the composition of the lithium solvation shell highlighting the importance of its characterization next to interface.…”

Phosphorus‐Based Materials for High‐Performance Alkaline Metal Ion Batteries: Progress and Prospect

“…[165] Xu et al have studied the cyclic behavior of LiPF 4 (C 2 O 4 ) (LiTFOB) with different types of graphite. [166] In the carbonate-based solvent, LiTFOB can perform reversible Li + intercalation/extraction on the LiNi 0.8 Co 0.2 O 2 cathode and graphite anode (Figure 12a), and shows superior performance to LiFP 6 indicating the formation of a stable interfacial phase.…”

“…The high ionic conductivity of this new material, coupled with the greatly reduced cost due to the substitution of Sn for Ge, makes Reproduced with permission. [166] Copyright 2011, IOP Publishing. b) Schematic representation of interphase formation between the Li metal and LiPON.…”

“…Figure 12. a) Voltage profiles of the MCMB/LiNi 0.8 Co 0.2 O 2, NG/LiNi 0.8 Co 0.2 O 2 , MCMB/LiFePO 4 , and NG/LiFePO 4 cells with 1.0 m LiPF 4 C 2 O 4 EC/EMC.Reproduced with permission [166]. Copyright 2011, IOP Publishing.…”