A High Precision Study of Electrolyte Additive Combinations Containing Vinylene Carbonate, Ethylene Sulfate, Tris(trimethylsilyl) Phosphate and Tris(trimethylsilyl) Phosphite in Li[Ni1/3Mn1/3Co1/3]O2/Graphite Pouch Cells

The effects of electrolyte additive combinations containing vinylene carbonate (VC), ethylene sulfate (DTD), tris(trimethylsilyl) phosphate (TTSP) and tris(trimethylsilyl) phosphite (TTSPi) in Li[Ni1/3Mn1/3Co1/3]O-2/graphite pouch cells have been investigated using the ultra high precision charger (UHPC) at Dalhousie University, electrochemical impedance spectroscopy (EIS), gas evolution measurements and long term cycling. The results show that combinations of electrolyte additives that act synergistically can be more effective than a single electrolyte additive (2% VC). These additive mixtures: reduce parasitic reactions at the positive electrode above 4.1 V compared to VC alone; improve coulombic efficiency, reduce charge end-point capacity slippage and also reduce impedance of the cells. A particularly useful additive combination is 2% VC + 1% DTD + 0.5% TTSP + 0.5% TTSPi. (C) The Author(s) 2014. Published by ECS. All rights reserved.