of 53
Supporting Information
Systematic Computational and Experimental Investigation of Lithium-ion
Transport Mechanisms in Polyester-based Polymer Electrolytes
Michael A. Webb,
Yukyung Jung,
Danielle M. Pesko,
Brett M. Savoie,
Umi
Yamamoto,
Geoffrey W. Coates,
Nitash P. Balsara,
,
§
,
Zhen-Gang Wang,
and
Thomas F. Miller III
,
Department of Chemistry and Chemical Engineering, California Institute of Technology,
Pasadena, California 91125, USA,
Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University,
Ithaca, New York 14853, USA,
Department of Chemical and Biomolecular Engineering, University of California, Berkeley,
Berkeley, California 94720, USA,
Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California
94720, USA, and
Environmental Energy Technology Division, Lawrence Berkeley National Laboratory,
Berkeley, California 94720, USA
E-mail: tfm@caltech.edu
To whom correspondence should be addressed
California Institute of Technology
Cornell University
University of California, Berkeley
§
LBNL- Materials Science Division
LBNL - Environmental Energy Technology Division
SI-1
Contents
1 Synthesis Details
SI-4
1.1 General Considerations: Synthesis . . . . . . . . . . . . . . . . . . . . . . . . SI-4
1.2 Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SI-4
1.3 Synthesis of 2-((2-(2-Methoxyethoxy)ethoxy)methyl)oxirane . . . . . . . . . SI-5
1.4 Synthesis of Catalysts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SI-6
1.4.1 Salicylaldehyde Synthesis . . . . . . . . . . . . . . . . . . . . . . . . . SI-6
1.4.2 N, N’-Bis(3-methyl-5-fluoro-salicylidene)-1,2-cyclohexadiimine SynthesisSI-9
1.4.3 (F-salcy)Cobalt(III)NO
3
Complex Synthesis . . . . . . . . . . . . . . SI-9
1.4.4 (
tert
-Butyl-salcy)Cobalt(III)NO
3
Complex Synthesis . . . . . . . . . SI-10
1.5 Copolymerization Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . SI-14
1.5.1 Synthesis of Polymer 1a . . . . . . . . . . . . . . . . . . . . . . . . . SI-14
1.5.2 Synthesis of Polymer 1b . . . . . . . . . . . . . . . . . . . . . . . . . SI-14
1.5.3 Synthesis of Polymer 2a . . . . . . . . . . . . . . . . . . . . . . . . . SI-14
1.5.4 Synthesis of Polymer 2b . . . . . . . . . . . . . . . . . . . . . . . . . SI-15
1.5.5 Synthesis of Polymer 3a . . . . . . . . . . . . . . . . . . . . . . . . . SI-15
1.5.6 Synthesis of Polymer 3b . . . . . . . . . . . . . . . . . . . . . . . . . SI-15
1.6 NMR Spectra for Polyesters . . . . . . . . . . . . . . . . . . . . . . . . . . . SI-16
1.6.1 Polymer 1a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SI-16
1.6.2 Polymer 1b . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SI-18
1.6.3 Polymer 2a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SI-20
1.6.4 Polymer 2b . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SI-22
1.6.5 Polymer 3a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SI-24
1.6.6 Polymer 3b . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SI-26
2 Simulation Protocol Details
SI-28
3 Electrochemical Characterization Details
SI-30
SI-2
4 Repeat Units and Terminal Groups for Polyesters in MD Simulations SI-31
5 Force Field Parameters for Molecular Dynamics Simulations
SI-33
5.1 Non-bonded Interaction Parameters . . . . . . . . . . . . . . . . . . . . . . . SI-34
5.2 Bonding Potential Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . SI-35
5.3 Bending Potential Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . SI-36
5.4 Torsional Potential Parameters . . . . . . . . . . . . . . . . . . . . . . . . . SI-37
6 Apparent Diffusivities in Simulation
SI-39
7 Experimental Dilute-ion Conductivities
SI-41
8 Effect of Terminal Group Interactions in Polymer 1a
SI-44
9 Correlation between
T
g
and Conductivity in MD Simulations
SI-46
10 Radial Distribution Functions for all Polymers
SI-47
11 Side chain Localization of Lithium Cation in Polymer 3a
SI-48
12 Backbone Localization of Lithium Cation in Type-1 and -2 Polymers SI-49
13 Comparison of Solvation-Site Networks
SI-51
SI-3
1 Synthesis Details
1.1 General Considerations: Synthesis
All air and water sensitive compounds were handled under dry nitrogen using a Braun
Labmaster Glovebox or standard Schlenk line techniques.
1
H and
13
C NMR spectra were
recorded on a Varian INOVA 400 (
1
H, 400 MHz) or Varian INOVA 500 (
1
H, 500 MHz)
spectrometer.
1
H NMR spectra were referenced with residual non-deuterated solvent shifts
(CHCl
3
= 7.26 ppm) and
13
C NMR spectra were referenced by solvent shifts (CDCl
3
= 77.16
ppm). Gel permeation chromatography (GPC) was performed using an Agilent PL-GPC
50 integrated system (2 x PLgel Mini-MIX C columns, 5 micron, 4.6 mmID) equipped with
a refractive index detector. The GPC columns were eluted with tetrahydrofuran at a rate
of 0.3 mL/min at 30
°C
, and samples were calibrated relative to polystyrene standards.
Differential scanning calorimetry (DSC) was performed on a Mettler-Toledo Polymer DSC
instrument equipped with a Julabo chiller and autosampler. DSC polymer samples were
prepared in crimped aluminum pans. All of the polyesters were analyzed using the following
DSC protocol: heating under nitrogen from -70
°C
to 200
°C
at 10
°C
/min, cooling from
200
°C
to -70
°C
at 10
°C
/min, and then heating from -70
°C
to 200
°C
at 10
°C
/min. The
data were processed using StarE software, and all reported glass transition temperatures
were obtained from the second heating cycle.
1.2 Materials
Calcium hydride (90%, Strem) was used as received to dry the epoxides. (
S
)-Propylene
oxide (Sigma-Aldrich) and allyl glycidyl ether (Sigma-Aldrich) were dried over calcium hy-
dride for 3 days, vacuum-transferred to a dry Schlenk adapted flask, and degassed via 3
freeze-pump-thaw cycles. The synthesis of 2-((2-(2-methoxyethoxy)ethoxy)methyl)oxirane
is described below. The purified 2-((2-(2-methoxyethoxy)ethoxy)methyl)oxirane was dried
over calcium hydride overnight, distilled into a dry Schlenk adapted flask, and degassed via
SI-4
3 freeze-pump-thaw cycles. Glutaric anhydride (Acros, 97%) was purified by suspending
in dichloromethane and washing with saturated aqueous sodium bicarbonate. The organic
layer was dried over
Na
2
SO
4
, filtered, and concentrated. The residue was washed with
ether, then dried under reduced pressure and sublimed. Diglycolic anhydride (Alfa Ae-
sar, 97%) was purified by sublimation. All epoxides and anhydrides were stored in the
glovebox immediately following purification. Metal precursor Co(NO
3
)
2
·
6H
2
O (>99% pu-
rity) was purchased from Strem and stored in a desiccator. Toluene and dichloromethane
were purchased from Fisher Scientific and purified using a Phoenix solvent drying system.
Bis(triphenylphosphine)iminium chloride (PPNCl) was purchased from Sigma-Aldrich and
recrystallized by layering dichloromethane and diethyl ether. NMR solvents were purchased
from Cambridge Isotopes and stored over 3 Å molecular sieves. All other reagents were
purchased from commercial sources and used as received.
1.3 Synthesis of 2-((2-(2-Methoxyethoxy)ethoxy)methyl)oxirane
Sodium hydride (60% in mineral oil, 5.65 g, 141 mmol) was added to a 250 mL round bottom
flask under nitrogen, then 160 mL of dried, degassed THF was added via cannula. The flask
was cooled to 0
°C
, and diethylene glycol methyl ether (13.3 mL, 113 mmol) was added
dropwise. The reaction was stirred for 30 minutes at 0
°C
, and then epichlorohydrin (22.1
mL, 282 mmol) was added dropwise. The reaction was warmed to room temperature, refluxed
for 2 hours under nitrogen, and then cooled to room temperature and stirred overnight. The
reaction was quenched with 20 mL ethanol, filtered through a pad of Celite, and then
concentrated to give a cloudy yellow oil. The crude product was distilled under reduced
pressure to yield 12.6 g (63% yield) of the product as a clear liquid. The
1
H NMR matched
those previously reported in the literature.
1
1
H NMR spectrum in ppm (CDCl
3
, 400 MHz):
δ
3.68 (dd, 1 H,
J
=
3.0, 11.6); 3.51-3.65 (m, 6H); 3.42-3.47 (m, 2H); 3.33 (q, 1 H,
J
=
5.9,
11.7 Hz); 3.27 (s, 3H); 3.05 (m, 1 H), 2.68 (t, 1 H,
J
=
4.7 Hz), 2.50 (dd, 1 H,
J
=
2.7, 5.0
Hz).
SI-5
1.4 Synthesis of Catalysts
The synthesis of catalyst 1 is described below. The ligand for catalyst 2 (N, N’-bis (3, 5-
tert
-
butyl-salicylidene)-1,2-cyclohexadiimine) was synthesized following literature procedures,
2
and the synthesis of the complex is described below.
1.4.1 Salicylaldehyde Synthesis
The salicylaldehyde was synthesized from 5-methyl-3-fluorophenol using a modified Duff
reaction as reported by Jacobsen et al.
3
The product was purified by column chromatography
(10% ether in hexanes to 15% ether in hexanes) to yield the product as a yellow crystalline
solid in 18% isolated yield. The
1
H NMR spectrum of the ligand precursor, 5-methyl-3-
fluorosalicylaldehyde, matches that previously reported in the literature.
4
1
H NMR spectrum
in ppm (CDCl
3
, 500 MHz):
δ
11.05 (s, 1 H); 9.81 (s, 1 H); 7.14 (dd,
J
=
2.1, 8.7, 1 H); 7.06
(dd,
J
=
3.1, 7.6, 1 H), 2.27 (s, 3H).
13
C NMR spectrum in ppm (CDCl
3
, 125 MHz):
δ
195.79;
156.45; 155. 33 (
J
CF
=239.4 Hz); 129.47; 125.46; 119.40; 115.21; 15.32. HR/MS: calculated
154.04301 g/mol; found 154.06623 g/mol.
SI-6
Figure S1:
1
H NMR spectrum of 5-methyl-3-fluorosalicylaldehyde in CDCl
3
.
SI-7
Figure S2:
13
C NMR spectrum of 5-methyl-3-fluorosalicylaldehyde in CDCl
3
.
SI-8
1.4.2 N, N’-Bis(3-methyl-5-fluoro-salicylidene)-1,2-cyclohexadiimine Synthesis
The salicylaldehyde (431.4 mg, 2.8 mmol) was dissolved in 7 mL of absolute EtOH at room
temperature. The racemic
trans
-1,2-diaminocyclohexane (168
μ
L, 1.4 mmol) was added,
and a yellow precipitate was observed after about 10 minutes of stirring. The reaction was
stirred at room temperature overnight. The mixture was diluted with 2 mL of water, and
the yellow solid was isolated by vacuum filtration. The solid was dried under vacuum to
give the ligand in 82% yield (445.9 mg).
1
H NMR spectrum in ppm (CDCl
3
, 500 MHz):
δ
13.27 (s, 1 H); 8.18 (s, 2H); 6.87 (dd,
J
=
2.9, 9.0, 2H); 6.70 (dd,
J
=
3.0, 8.3, 2H); 3.31
(m, 2H); 2.23 (s, 6H); 1.40-2.00 (m, 8H).
13
C NMR spectrum in ppm (CDCl
3
, 125 MHz):
δ
164.10; 155. 49; 154.93; 127.76; 120.37; 117.46; 113.87; 72.77; 33.19; 24.25; 15.71. HR/MS:
calculated 387.18786 g/mol (M+H); found 387.18735 g/mol.
1.4.3 (F-salcy)Cobalt(III)NO
3
Complex Synthesis
The (F-salcy)cobalt(III)NO
3
complex was synthesized according to literature procedure.
5
The ligand, N, N’-bis(3-methyl-5-fluoro-salicylidene)-1,2-cyclohexadiimine (350 mg, 0.906
mmol), was dissolved in dichloromethane in a flame-dried Schlenk flask under nitrogen.
In a separate flame-dried Schlenk flask, Co(NO
3
)
2
·
6H
2
O was dehydrated by heating to 60
°C
under reduced pressure until the color changed from red to light pink. The dehydrated
Co(NO
3
)
2
·
6H
2
O was dissolved in anhydrous, degassed ethanol and subsequently added to
the ligand solution via cannula. The mixture was stirred for 15 minutes under nitrogen,
then exposed to dry air by attaching a drying tube charged with Drierite to the top of
the flask. The reaction was stirred under dry air overnight to oxidize the complex. The
reaction mixture was evacuated to dryness, washed with pentanes, and dried under reduced
SI-9
Figure S3:
1
H NMR spectrum of N,N’-bis(3-methyl-5-fluoro-salicylidene)-1,2-cyclohexadiimine in
CDCl
3
.
pressure. The resulting dark green powder (396.4 mg, 86% isolated yield) was stored in a
glovebox under nitrogen.
1
H NMR spectrum (
C
5
D
5
N, 500 MHz):
δ
8.83 (2H); 7.39 (2H);
4.16 (
1
H); 3.21 (
1
H); 2.83 (6H); 1.5-2.3 (8H).
13
C NMR spectrum (
C
5
D
5
N, 125 MHz):
δ
167.27; 161.53; 154.41; 139.66; 134.06; 117.31; 116.40; 71.55; 30.85; 25.35; 18.01. HR/MS:
calculated 443.09813 g/mol (for salcyCo
+
); found 443.09727 g/mol.
1.4.4 (
tert
-Butyl-salcy)Cobalt(III)NO
3
Complex Synthesis
The (
tert
-Butyl-salcy)Cobalt(III)NO
3
complex was synthesized following the same procedure
as in 4.3 using the N, N’-bis(3, 5-
tert
-butyl-salicylidene)-1,2-cyclohexadiimine ligand.
SI-10
Figure S4:
13
C NMR spectrum of N,N’-bis(3-methyl-5-fluoro-salicylidene)-1,2-cyclohexadiimine in
CDCl
3
.
SI-11
Figure S5:
1
H NMR spectrum of (F-salcy)cobalt(III)NO
3
complex in
C
5
D
5
N.
SI-12
Figure S6:
13
C NMR spectrum of (F-salcy)cobalt(III)NO
3
complex in
C
5
D
5
N.
SI-13
1.5 Copolymerization Procedures
1.5.1 Synthesis of Polymer 1a
In the glovebox, catalyst 1(12.6 mg, 0.025 mmol), PPNCl (14.4 mg, 0.025 mmol), glutaric
anhydride (850 mg, 7.5 mmol), and 0.66 mL toluene were added to a dry 4mL scintillation vial
equipped with a stirbar. The epoxide (
S
)-propylene oxide (0.61 mL, 8.7 mmol) was added via
syringe, and the vial was sealed with a Teflon lined cap. The reaction vial was then removed
from the glovebox and stirred at 50
°C
for 19 h. The polymerization was quenched with
a solution of 5 equiv. (relative to catalyst)
p
-toluenesulfonic acid in acetone, diluted with
a minimum volume of dichloromethane, and precipitated into hexanes. The precipitation
process was repeated until no residual monomer was observed by
1
H NMR spectroscopy.
The polymer was dried under reduced pressure at room temperature overnight.
1.5.2 Synthesis of Polymer 1b
Catalyst 1 (9.6 mg, 0.019 mmol), PPNCl (10.7 mg, 0.019 mmol), diglycolic anhydride (650
mg, 5.6 mmol), and 0.5 mL toluene were added to a dry 4 mL scintillation vial with a stirbar.
The epoxide (
S
)-propylene oxide (0.52 mL, 7.4 mmol) was added via syringe, and the vial
was sealed with a Teflon lined cap. The reaction was stirred for 20 h at 55
°C
, and quenched
with 5 equiv. of
p
-toluenesulfonic acid in acetone (relative to catalyst), and precipitated in
methanol. The polymer was dried under vacuum at room temperature overnight.
1.5.3 Synthesis of Polymer 2a
Catalyst 1 (7.1 mg, 0.014 mmol), PPNCl (8.0 mg, 0.014 mmol), glutaric anhydride (480 mg,
4.2 mmol), and 0.5 mL toluene were added to a dry 4 mL scintillation vial with a stirbar.
The epoxide allyl glycidyl ether (0.5 mL, 4.2 mmol) was added via syringe, and the vial was
sealed with a Teflon lined cap. The reaction was stirred at 55
°C
for 22 h and quenched
with 5 equiv. of
p
-toluenesulfonic acid (relative to catalyst) in acetone. The polymer was
SI-14
precipitated in MeOH and dried under vacuum at room temperature overnight.
1.5.4 Synthesis of Polymer 2b
Catalyst 1 (7.1 mg, 0.014 mmol), PPNCl (8.0 mg, 0.014 mmol), diglycolic anhydride (489
mg, 4.2 mmol), and 0.3 mL toluene were added to a dry 4 mL scintillation vial with a stirbar.
The epoxide allyl glycidyl ether (0.5 mL, 4.2 mmol) was added via syringe, and the vial was
sealed with a Teflon lined cap. The reaction was stirred at 25
°C
for 25 h, and quenched
with 5 equiv. of
p
-toluenesulfonic acid (relative to catalyst) in acetone. The polymer was
precipitated in methanol and dried under vacuum at room temperature overnight.
1.5.5 Synthesis of Polymer 3a
Catalyst 1 (6.8 mg, 0.013 mmol), PPNCl (7.7 mg, 0.013 mmol), glutaric anhydride (450 mg,
3.9 mmol), and 0.3 mL toluene were added to a dry 4 mL scintillation vial with a stirbar.
The epoxide 2-((2-(2-methoxyethoxy)ethoxy)methyl)oxirane (500 mg, 4.6 mmol) was added
via syringe, and the vial was sealed with a Teflon lined cap. The reaction was stirred at
55
°C
for 25 h, and quenched with 5 equiv. of
p
-toluenesulfonic acid (relative to catalyst)
in acetone. The polymer was precipitated in hexanes and dried under vacuum at room
temperature overnight.
1.5.6 Synthesis of Polymer 3b
Catalyst 2 (4.0 mg, 0.0080 mmol), PPNCl (4.6 mg, 0.0090 mmol), diglycolic anhydride (458
mg, 4.0 mmol), and 0.3 mL toluene were added to a dry 4 mL scintillation vial with a
stirbar. The epoxide 2-((2-(2-methoxyethoxy)ethoxy)methyl)oxirane was added via syringe,
and the vial was sealed with a Teflon lined cap. The reaction was stirred at 55
°C
for 28
h, and quenched with 5 equiv. of
p
-toluenesulfonic acid (relative to catalyst) in acetone.
The polymer was precipitated in hexanes and dried under vacuum at room temperature
overnight.
SI-15
1.6 NMR Spectra for Polyesters
1.6.1 Polymer 1a
1
H NMR spectrum (CDCl
3
, 500 MHz):
δ
5.13 (m, 1 H); 4.18 (dd,
J
=
3.4, 11.7 Hz, 1 H);
4.03 (dd,
J
=
6.6, 11.8 Hz, 1 H); 2.38 (dt,
J
=
7.4, 7.4, 11.4 Hz, 4H); 1.93 (tt,
J
=
7.3, 7.3,
7.4, 7.4 Hz, 2H); 1.24 (d,
J
=
6.5 Hz, 3H).
13
C NMR spectrum (CDCl
3
, 125 MHz):
δ
172.67;
172.34; 68.34; 66.14; 33.44; 33.09; 20.12; 16.66.
Figure S7:
1
H NMR spectrum of polymer 1a in CDCl
3
.
SI-16
Figure S8:
13
C NMR spectrum of polymer 1a in CDCl
3
.
SI-17