Coin cells containing the additives, vinylene carbonate (VC) and tris(trimethylsilyl)phosphite (TMSPi), in the range of 0 to 0.020 wt. fraction, were cycled between 3.0 and 4.4 V. The changes in C/10 and C/1 capacity and cell resistance at 60% SOC were found to follow linear-with-time kinetic rate laws. After aging, the electrodes were characterized by X-ray photoelectron spectroscopy. The concentration of some surface species correlated very strongly with changes in cell performance.

Further, the cell performance data could be modeled using a statistics of mixtures approach. The modeling indicated that there was a strong, synergistic interaction between VC and TMSPi, as expected. The interaction between these additives lessened capacity fade. These results, as well as others, will be discussed.

Acknowledgment

The work at Argonne National Laboratory was performed under the auspices of the U.S. Department of Energy (DOE), Office of Vehicle Technologies, under Contract No.
DE-AC02-06CH11357. The U.S. Government retains for itself, and others acting on its behalf, a paid-up nonexclusive, irrevocable worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the Government.