V. Focused Fundamental Research - EERE - U.S. Department of ...

Scherson, Protasiewicz – CWRU
V.D.4 Bi-functional Electrolytes for Lithium-ion Batteries (CWRU)
Figure V - 148: TGA of the first generation FRIons.
To demonstrate the feasibility of the FRIons acting
as a bifunctional electrolyte, our collaborators at
Novolyte Technologies incorporated two of our salts, as
additives a the 2% level, into 2325 coin cells with a
graphite anode and a LiCoO 2 cathode. The cell was
cycled at 1 mA between 4.2 and 2.5 V in 1M LiPF 6 in
EC/EMC (3:7 by vol) + 1.5% VC (Figure V - 149). As
indicated, LiC Me B Ph displayed improved performance
over the baseline for long term cycling.
5.5
5.0
4.5
4.0
3.5
3.0
mAh
2.5
2.0
1.5
1.0
0.5
Baseline
LiC Me
B Ph
LiOxBOAr
0.0
0 10 20 30 40 50 60 70 80
Cycle Number
Figure V - 149: Capacity versus cycle number for the specified electrolyte formulations.
Spectroscopic Studies.
External reflection FTIR. The ATR-FTIR cell
was modified to perform measurements in the external
reflection mode (IRAS) using a CaF 2 window and p-
polarized light to enhance surface spectral contributions.
IRAS data were collected in 1M LiPF 6 in EC/EMC (3:7
by vol) with the Ni electrode pressed against the
window while scanning the potential from the open
circuit value (OCP ca. 2.2 V) down to 0.05 V vs Li/Li + .
Representative results are shown in Fig. 4 as ΔR/R =
(R OCP - R samp )/R OCP , where R is the single beam
spectrum and samp refers to the potential at which the
specific spectrum was recorded. The arrows in Figure V -
150 point to the peaks associated with solvated PF 6 - the
intensity of which decreases for decreasing potentials
due to migration in and out of the trapped electrolyte
FY 2011 Annual Progress Report 607 Energy Storage R&D