New Polymeric Proton Conductors High Temperature Applications · New Polymeric Proton Conductors...
Transcript of New Polymeric Proton Conductors High Temperature Applications · New Polymeric Proton Conductors...
New Polymeric Proton Conductors for
High Temperature Applications
John Kerr, Xiao-Guang Sun, Gao Liu, Jiangbing Xie and Craig Reeder
Lawrence Berkeley National Laboratory,MS 62R0203, 1 Cyclotron Road,
Berkeley CA, [email protected]
Outline
• Background– Solid Polymer vs. Gel Polymer Ion Transport– Lithium ion transport vs. Proton transport.– Common features for Lithium Polymer batteries
and PEMFC’s.• Polymer design & Synthesis.• Preliminary Results• Future schedule and testing development
Liquids vs. Gels vs. Dry PolymersTransport mechanisms differ
(blue: polymer chain; red: cross-linker; black: solvent)
Li+
Li+
Li+
X-
X-
X-
One or both ions are solvated by polymer.Ions move due to segmental motion ofpolymer. Need 850C for EV performance
Dry Polymer – Li Metal/polymer &Fuel Cells –High Temp PEM (1500C)Gel Polymer – Li Ion and Fuel Cell
Li+
Li+
Li+
X-
X- X-
Network Backbone may be polymer or inorganic. Free liquid moves with ions. Operates at ambient temp.
Anions may be tethered to polymer backbone by means of side chains.Molecular structure determines morphology and properties.
Fuel Cell MembranesMicroscopic to Macroscopic
Anions tethered to polymer. Cations (H+, Na+)are mobile and solvated by water. Molecular structure determines morphology and formation of ionic, water-rich clusters.
Fuel Cell Composite Electrodes.
O2
Current collector
X-
X-
X-
X-
X-
X-
X-
X- X-
H+
H+
H+
H+
H+
H+
Nafionmembrane
O2H+
Carbon electrode particles
= conductingcarbon particle
Gas Phase •Transport of gases and ions through crowdedpolymer-solid interfaceswhere the electrolyte mobility is restricted.• Polyelectrolytes close to glassy phase in presence of electrode surfaces.•Poor ion transport and dis-bondment.•Ion activity?
Composite Electrodes in Li Ion CellsLithium ions in crowded neighborhoods
Cur
rent
col
lect
or
Carbon/graphiteparticles for intercalation
Li+
Li+
Li+
Li+
Li+Li+
Li+
Li+
Li+X-
X-
X-
X-X-
X-
Cur
rent
col
lect
or
separatorAnode Cathode
Ions plus solvent (EC/DMC, DME) – Unstable!Leads to gas generation and polymer formation
= cathode particle= Conducting carbon particle
Mechanisms of Ion Mobility in “Dry”Polymers - Amorphous Phase
O
O O
O
OO
O
O Li+Li+
Arrhenius Control-related tosolvation
O
Controlled by Segmental Motion- related to glass transition temperature, Tg
New Polymer Architectures for ImidazoleSolvating groups, Anion Mobility and
Flexibility
O
F2C
SO2
N
SO2
F3C
O O
O
N
N
O
O
N
N
O
O
n
bdo
n
pdo
nn
pdo bdo
Imidazole H+ solvating group
Imide Anion
H+
•Attach anions and solvatinggroups by grafting –control nature and concentration.•Use nature (pdo/bdo) and length of side chainto control chain mobility.•Backbone (PE, polystyrene,polysiloxane) and cross-linkdensity to control mechanical & morphological properties.•Degradation results in Release of small fragments- facilitates failure analysis.
Imidazole Proton Conductivity
Grotthus Proton Transfer?
Oxygen Separation Membraneexhibits stability to (per)oxygen
•Vinyl Imidazole used rather than vinyl pyridine.•PolyvinylImidazole has highTg. Membrane is very selectivefor O2 over N2.
Hiroyuki Nishide,* Yukihiro Tsukahara, and Eishun Tsuchida, J. Phys. Chem. B, 102 (44), 8766 -8770, 1998.
Hydrosilylation Chemistry Allows Grafting of Functions (Anions or Imidazoles) and Cross-
linking for Mechanical Properties.O
O
O
x yX-link catalyst
OO
O
x y
X
OO
O
y x
Graft Reaction
X O
C(SO2CF3)2
Li
OO
O
x y
Single-Ion ConductorX-Linked Network- may link different polymers to stabilize blends for cost savings
X OC(SO2CF3)2
Li
))))
))
))
((( (
((
((
-allyl groups are reactive centers in this chemistry.-Hydrosilation is reproducible, provides better uniformity and leaves no residues. -Allyl groups do not react with radical initiators
HSi Si
HX =
Prepolymers and Salts
OB
O
O
OO O
OO
Li+
SO2CF3
SO2CF3Li +
OSO3Li+
F F
FFFF
F F
Salt I
Salt II
Salt III
*O
O*
O
O
O
O
O
O
O
O
x
Prepolymer
OO SO3Li+
OO
OO
SO3Li
O O SO3Li
Salt IV
Salt V
Salt VI
y
CH2=CH-CH2-O-CF2-CFH-O-CF2-CF2-SO2N(Li)SO2CF3
CH2=CH-CH2-O-CF2-CFH-O-CF2-CF2-SO3(Li)
New salts arriving from DesMarteau Group (Clemson)
Conductivity of Li+
Polyelectrolytes
-9
-8
-7
-6
-5
-4
2.6 2.8 3 3.2 3.4 3.6 3.8 4
Ionic Conductivity of Comb-branch SIC as a Function of Temperature
SIC-25SIC-45SIC-80
1000/T (K-1)
•Theoretical modelspredict optimumion concentrationto be half the optimum for binarysalts.(Ratner JES 148,A858 (2001))
•Low salt concn. giveslower cost pathway.•Lower Tg at higherion concn. wanted forhigh conductivity. •Side chain lengths and flexibility not optimized.Tg: 80 = -54oC; 45 = -53oC; 25 = -35oC
Synthesis of Prepolymers & SaltsCl O
OO OH O O OOa
b
O O OHO O OO2
O O OH2
b
Cl OO
a
Cl OO
aO O O
O3
b
O O OH3
Cl
cO O4
O O2O OH
2
Cl
c
O O4
O O2
+K tert-Butoxide
OO
O
O
O
O
O
O
O
O
x
PETMO4
Note: a. NaOH/H2O (50/50), tetrabutylammonium hydrogen sulfate (THS), Toluene b. Methanol, H2O, HCl c. NaOH/H2O (50/50), THS
65oC
ICF2CF2OCF2CF2SO2F O
O+
Benzoyl peroxide
O
O
IO
SO2F
F F
F F F F
F F
Zn
OSO2F
F F
F F F F
F F OSO3Li
F F
F F F F
F F
LiOH
Salt III
OOH
Cl OO
OO
O O
H+
OO
OHOO
ClSOCl2
Na2SO3
OO
SO3Na OO
SO3Li
Salt IV
1. Ion exchange
2. LiOH
NaOH/H2O, catalyst
Conductivities of Lithium Polyelectrolytes
2.4 2.6 2.8 3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4-9.5
-9.0
-8.5
-8.0
-7.5
-7.0
-6.5
-6.0
-5.5
-5.0
-4.5
100oC 25oC
Log σ
/ S.c
m-1
1000 / T ( K -1)
Methide LiBAMB C2F4OC2F4SO3Li E4SO3Li E2SO3Li TMO2SO3Li
2.4 2.6 2.8 3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4
-9.5
-9.0
-8.5
-8.0
-7.5
-7.0
-6.5
-6.0
-5.5
-5.0
-4.5
DSC results of PETMO4 based single ion conductors
-79.0154C2F4OC2F4SO3LiPETMO4-40
-78.0652MethidePETMO4-40
-79.5954TMO2SO3LiPETMO4-40
-78.7256E4SO3LiPETMO4-40
-79.0754E2SO3LiPETMO4-40
-86.770----PETMO4-40
-78.5348LiBAMBPETMO4-20
-85.660---PETMO4-20
Tg/oCO/LiSaltPrepolymer
Uniformity of the Membrane is Critical!Rheology(DMTA) and AFM probe Membrane Properties and Uniformity – PEPE3+ 10% AGE
-100.0 -50.0 0.0 50.0 100.0 150.0105
106
107
108
109
10-2
10-1
100
101
Temp [°C]
E
' ()
[dy
n/cm
2 ]
E"
()
[dy
n/cm
2 ]
tan_delta ()
[ ]
PEPE3_Silane-X_Tg_third
2nd Tg
Tg
Rapid growth of dendrites observed in Li/Li cells – due to thick membrane (400µm), high x-link density that degrades
transport properties and non-uniformity from non-random polymer
Comb Structures allow Increase of Mechanical strength without Loss of Ion transport Properties?
PEPE3 (no salt) with different amount of crosslinker
-120.0 -104.0 -88.0 -72.0 -56.0 -40.0 -24.0 -8.0 8.0 24.0 40.00.0
0.5
1.0
1.5
2.0
2.5
Temp [°C]
tan
_del
ta (
)
[ ]
-120.0 -104.0 -88.0 -72.0 -56.0 -40.0 -24.0 -8.0 8.0 24.0 40.0104
105
106
107
108
109
1010
Temp [°C]
E
' ()
[dy
n/cm
2 ]
Increase crosslinker
Increase crosslinker
Increase of X-link agent leaves fewer free allyl groups available to alter polymer morphology
PEPE3/LiTFSI 20:1 with different amounts of hydrophobic SiO2 R805 filler
-100 -80 -60 -40 -20 0 20 40 60 80 1000
2
tan
delta
Temperature (oC)
Increasing SiO2: 0, 5, 10, 20%
-100 -80 -60 -40 -20 0 20 40 60 80 100
0
2
tan
delta
Temperature ( oC)
Combine X-link Chemistry with fillers for Increased Mechanical Properties
Different Surface Interactions influence Polymer Mobility (Temperature Sweep in Compression (10Hz))Fumed SiO2 -A200 –OH hydrophilic groups
R805 – Octyl hydrophobic groups
-80.0 -53.333 -26.667 0.0 26.667 53.333 80.00.0
0.2857
0.5714
0.8571
1.1429
1.4286
1.7143
2.0
Temp [°C]
tan
_del
ta (
)
[ ]
X-PEPE3_LITFSI (20:1)
tan_delta no filler 5% hydrophobilc SiO210% hydrophobic SiO210% hydrophilic SiO2
-80.0 -53.333 -26.667 0.0 26.667 53.333 80.0104
105
106
107
108
109
1010
Temp [°C]
E
' ()
[dy
n/cm
2 ]
X-PEPE3_LITFSI (20:1)
E' no filler 5% hydrophobic SiO210% hydrophobic SiO210% hydrophilic SiO2
PEPE3copolymer with 20% AGE-LiTFSI (20:1). X-linked to 10% density.Note increase in Tg due to presence of salt (cf. X-link with no salt).
Single-ion Conductor Gels.Add solvent to increase Ion transport to
Useful Levels.
-12
-10
-8
-6
-4
-2
2.5 3 3.5 4
Ionic conductivity for PAE8.66
based single ion conductors
before and after plasticized with PC/EMC (1/1, v/v)
PAE8.66-g-E2SO3NaPAE8.66-g-E2SO3LiPAE8.66-g-E3SO3NaPAE8.66-g-E3SO3LiPlasticized PAE8.66-g-E2SO3NaPlasticized PAE8.66-g-E2SO3LiPlasticized PAE8.66-g-E3SO3NaPlasticized PAE8.66-g-E3SO3Li
Log σ/
S.cm
-1
1000/T (K-1)
25oC
-10
-9
-8
-7
-6
-5
-4
-3
-2
2.5 3 3.5 4
Ionic conductivity for PEPE3 based single ion conductorsbefore and after plasticized with PC/EMS (1/1, v/v)
PEPE3-g-E2SO3NaPEPE3-g-E2SO3LiPEPE3-g-E3SO3LiPEPE3-g-E3SO3NaPlasticized PEPE3-g-E2SO3NaPlasticized PEPE3-g-E2SO3LiPlasticized PEPE3-g-E3SO3NaPlasticized PEPE3-g-E3SO3Li
Log σ/
S.cm
-1
1000/T (K-1)
25oC
Imidazoles and Long Tethers good for Hydrogels- Heller
Imidazole provides stabilityand faster kinetics.Long tether provides faster diffusionand leads to order of magnitudeIncreas in current.
Hydrogels used for bionsensors,medical applications, etc.
New Opportunities for Old Technologies?
Organic &Polymer
ElectrochemistryLithium Batteries
FuelCell
Membranes
LED flat panelDisplays
IonExchange materials
biomembranes &biocatalysis
Environmental preservation &
remediation
Gasseparation
Biotechnology bioprocessing
sensors
Electric Vehicles- Transportation
Energy generation
Photo-voltaics
Electrochemi-luminescence
chemical manufacturing
Selective ChemicalSynthesis
Selective Membranes
Pharmaceuticals &Intermediates
Electro-chromic devices
SmartWindows -EnergyEfficiency
Ozone/peroxidegeneration
Biotechnologyfor the
Environment
New
EETD/LB
NL O
pportunitiesEs
tabl
ishe
d EE
TD/L
BN
L Pr
ogra
ms
Next Steps
• Prepare polyelectrolyte acid forms (usually from Na+ form)
• Measure “dry” conductivity, Tg-values and mechanical properties.
• Dope with imidazole, pyridine and water.– Measure conductivity, Tg and rheology.
• Examine polymer stability.• Attach Imidazole to polyelectrolyte and
measure properties.
Next Phase
• Optimize polyelectrolyte structure for transport– Concentration of imidazole, anions– Tether length and flexibility– Backbone and cross-linking
• Examine material properties with carbon filler for potential MEA construction.
• Develop more stability data.• Initiate development of structure-function
relationships
Acknowledgements
• DOE-LANL• NASA PERS program (Glenn Research
Center).• DOE Office of FreedomCAR and Vehicle
Technologies