Electronic Supplementary Information · XL-VK-1 VK: Temperature (o C) Fig. S7. DSC curves collected...

1

Electronic Supplementary Information

Crosslinked Fluoropolymers Exhibiting Superior High-Temperature Energy Density and

Charge–Discharge Efficiency

He Li, Matthew R. Gadinski, Yuqi Huang, Lulu Ren, Yao Zhou, Ding Ai, Zhubing Han, Bin Yao

and Qing Wang

Department of Materials Science and Engineering, The Pennsylvania State University,

University Park, Pennsylvania, 16802, USA.

Electronic Supplementary Material (ESI) for Energy & Environmental Science.This journal is © The Royal Society of Chemistry 2020

2

100 200 300 400 500 600

0

1

2

3

4

5

6

7

BOPP

VK

Dis

charg

ed

Energ

y D

ensity (

J c

m-3)

0

10

20

30

40

50

60

70

80

90

100

Electric Field (MV m-1)

@ 25 oC

Charg

e-D

ischarg

e E

ffic

iency (

%)

Fig. S1. Discharged energy density and charge–discharge efficiency of BOPP and VK at room

temperature. Error bars represent standard deviations obtained from at least three measurements

using different samples.

3

0 100 200 300 400 500 600 700

0

1

2

3

4

5

6

7

8

9

10

25 oC

100 oC

150 oC


Dis

charg

ed E

nerg

y D

ensity (

J c

m-3)

0

10

20

30

40

50

60

70

80

90

100

Ch

arg

e-D

ischarg

e E

ffic

iency (

%)

Fig. S2. Discharged energy density and charge–discharge efficiency of VK at varied temperatures.

Error bars represent standard deviations obtained from at least three measurements using different

samples.

4

Fig. S3. The mechanism of crosslinking reaction of XL-VK.

Ⅲ Crosslinking reaction

Ⅰ Initiation

Ⅱ Propagation

5

Fig. S4. (a) Cross-sectional SEM image of XL-VK-2 film with a thickness of 10.8 μm.

Photographs of XL-VL-2 films (b) before and after (c) socking in a high-temperature insulation

fluid at 150 oC for 24 h. The crosslinked films maintain the flatness, transparency and flexibility,

exhibiting excellent thermal stability.

6

1800 1600 1400 1200 1000 800 600 400

C-Cl

C-F2

C-F

C=CC=O

XL-VK-3

XL-VK-2

XL-VK-1

VK

Absorb

ance (

a.u

.)

Wavenumber (cm-1)

Fig. S5. ATR-FTIR spectra of VK and XL-VK. The peaks at 1470 cm–1 and 1700 cm–1 in the XL-

VK spectra correspond to the double bond formation and the carbonyl of the triallyl isocyanurate

(TAIC), respectively.1,2 These groups have been shown to act as charge traps in the crosslinked

polymers.3,4 The peaks at 1282 cm–1 and 665 cm–1 are attributed to the C-F and C-Cl bonds of the

polymer backbones, respectively.2,5,6 The ratio of the intensities of the C-F peak to the C-Cl peak

were taken and normalized to 3.05 (to account for the 2.5 mol% VDF in VK) for the pristine VK.2

The ratio after crosslinking is 3.13, 3.22 and 3.30 for XL-VK-1, -2, -3, which correspond to a

2.4%, 5.7% and 8.2% decrease in chlorine, respectively.

7

1400 1200 1000 800 600 400 200 0 -200

200 202 204 206

Area ratio%:

peak 1/ peak 2

= 0.53

Court

pe

r S

econd

(a.u

.)

Binding Energy (eV)

Experimental

Cl 2p peak 1

Cl 2p peak 2

Peak fitting

Atomic ratio%:

F/Cl = 2.38

Cl 2p

VKa

Co

urt

pe

r S

eco

nd

(a

.u.)

Binding Energy (eV)

F 1s

1400 1200 1000 800 600 400 200 0 -200

200 202 204 206

Area ratio%:

peak 1/ peak 2

= 0.52

Co

urt

pe

r S

eco

nd

(a

.u.)

Binding Energy (eV)

Experimental

Cl 2p peak 1

Cl 2p peak 2

Peak fitting

Atomic ratio%:

F/Cl = 2.81

b XL-VK-1

Co

urt

pe

r S

eco

nd

(a

.u.)

Binding Energy (eV)

F 1s

Cl 2p

1400 1200 1000 800 600 400 200 0 -200

200 202 204 206

Area ratio%:

peak 1/ peak 2

= 0.52

Co

urt

pe

r S

eco

nd

(a

.u.)

Binding Energy (eV)

Experimental

Cl 2p peak 1

Cl 2p peak 2

Peak fitting

Atomic ratio%:

F/Cl = 3.70

XL-VK-2c

Co

urt

pe

r S

eco

nd

(a

.u.)

Binding Energy (eV)

F 1s

Cl 2p

1400 1200 1000 800 600 400 200 0 -200

200 202 204 206

Area ratio%:

peak 1/ peak 2

= 0.53

Court

pe

r S

econd

(a.u

.)

Binding Energy (eV)

Experimental

Cl 2p peak 1

Cl 2p peak 2

Peak fitting

Atomic ratio%:

F/Cl = 3.82

XL-VK-3d

Court

pe

r S

econd (

a.u

.)

Binding Energy (eV)

F 1s

Cl 2p

Fig. S6. XPS spectra of VK and XL-VK. Insets show the high-resolution XPS of Cl 2p. The peaks

of Cl 2p were fitted by using “Peak Add” of Thermo Advantage, the area ratios of peak 1/peak 2

are around 0.52~0.53 for all the VK and XL-VK samples, which indicates that the crosslinking

reaction does not change the chemical status of chlorine. The atomic ratio of F/Cl was calculated

by using Survey Spectrum of Thermo Advantage, which increases from 2.38 of pristine VK to

2.81, 3.70 and 3.82 of XL-VK-1, XL-VK-2, and XL-VK-3, respectively. The increased atomic

ratio F/Cl is due the elimination of chlorine groups from chlorotrifluoroethylene because of

crosslinking reaction, which is consistent with the trend shown in ATR-FTIR measurements.

8

100 120 140 160 180 200 220 240

Tm= 193

oC

Tm= 196

oC

Tm= 198

oC

Tm= 215

oC

XL-VK-3

XL-VK-1

XL-VK-2

He

at

flo

w (

a.u

.) e

xo

the

rm →

Temperature (oC)

VK

a

100 120 140 160 180 200 220 240

b

Tc= 149

oC

Tc= 153

oC

Tc= 156

oC

Tc= 175

oC

XL-VK-3

XL-VK-2

XL-VK-1

VK

Heat

flow

(a.u

.) e

xoth

erm

→

Temperature (oC)

Fig. S7. DSC curves collected during (a) the heating cycle and (b) the cooling cycle of VK and

XL-VK. Crosslinking was found to decrease the melting temperature, the crystallization

temperature as well as crystallinity of XL-VK with respect to the pristine VK. The crystallinity

was calculated as7,8

sDSC

0

100%H

XH

=

(S1)

9

where XDSC is the calculated crystallinity from DSC curve, ΔHs is the heat of fusion integrated

from melting peak of DSC curve and ΔH0 of 43 J g–1 is the corrected heat of fusion of a 100%

crystalline PCTFE.7,8 This calculation assumes that the heat of fusion is independent of the co-

monomer content used here (2.5 mol%). The XDSC was found to drop from 40.1% in pristine VK

to 21.1%, 19.3% and 10.8% in XL-VK-1, -2 and -3. The melting temperature decreases from 215 oC for pristine VK to 198 oC, 196 oC and 193 oC for XL-VK-1, -2 and -3. The crystallization

temperature decreases from 175 oC for pristine VK to 156 oC, 153 oC and 149 oC for XL-VK-1, -

2 and -3. Further decrease in melting temperature is relevant as it suggests a decrease in crystallite

size9.

10

10 12 14 16 18 20 22 24

Experimental

Peak fitting

Amorphous

(101)

(102)

(103)

(104)

2θ (deg.)

Rela

tive Inte

nsity (

a.u

.)

VKa

10 12 14 16 18 20 22 24

Experimental

Peak fitting

Amorphous

(101)

(102)

(103)

(104)

XL-VK-1

2θ (deg.)

Rela

tive Inte

nsity (

a.u

.)

b

10 12 14 16 18 20 22 24

XL-VK-2

2θ (deg.)

Rela

tive Inte

nsity (

a.u

.)

c Experimental

Peak fitting

Amorphous

(101)

(102)

(103)

(104)

10 12 14 16 18 20 22 24

dXL-VK-3

2θ (deg.)

Re

lative Inte

nsity (

a.u

.)

Experimental

Peak fitting

Amorphous

(101)

(102)

(103)

(104)

Fig. S8. XRD spectra of VK and XL-VK. All data were analyzed using Jade software with a

Gaussian-Lorentz superposition fitting function. The crystallinity calculated from XRD (XXRD) are

consistently higher than that of DSC results.8 The decrease in crystallite size is also confirmed by

the XRD curves, indicating little difference between the pristine and crosslinked polymers, but all

show the same crystalline phase of PCTFE. The crystallite size of XL-VK, however, is observed

to be smaller which is visible in spectra as the broadening of the peaks no longer allows the

shoulder of each plane from being visible as they are in pristine VK. The spectra of all samples is

a result of 4 peaks located at about 16.3°, 16.7°, 17.3°, and 18.2° 2θ corresponding to the (101),

(102), (103), and (104) planes, respectively.8

11

Table S1. Crystallographic parameters of VK and XL-VK.

Sample

Crystallinity

by DSC

(XDSC)

Crystallinity

by XRD

(XXRD)

Crystallite

size

d(101) (nm)

Crystallite

size

d(102) (nm)

Crystallite

size

d(103) (nm)

Crystallite

size

d(104) (nm)

VK 40.1% 77.9% 42.5 41.6 25.6 16.5

XL-VK-1 21.1% 70.4% 35.2 31.9 24.0 23.2

XL-VK-2 19.3% 66.9% 33.6 28.6 22.9 17.0

XL-VK-3 10.8% 62.8% 30.0 18.2 13.4 7.0

12

-50 -25 0 25 50 75 100 125 150 175 2001.5

1.8

2.1

2.4

2.7

3.0

3.3

3.6

3.9

VK

103 Hz

104 Hz

105 Hz

106 Hz

Temperature (oC)

K

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

tan

a

-50 -25 0 25 50 75 100 125 150 175 2001.8

2.1

2.4

2.7

3.0

3.3

3.6

3.9 10

3 Hz

104 Hz

105 Hz

106 Hz

b XL-VK-1

Temperature (oC)

K

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

tan

-50 -25 0 25 50 75 100 125 150 175 2001.8

2.1

2.4

2.7

3.0

3.3

3.6

3.9c

Temperature (oC)

K

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08 10

3 Hz

104 Hz

105 Hz

106 Hz

XL-VK-2

tan

13

-50 -25 0 25 50 75 100 125 150 175 2001.8

2.1

2.4

2.7

3.0

3.3

3.6

3.9d XL-VK-3

Temperature (oC)

K

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08 10

3 Hz

104 Hz

105 Hz

106 Hz

tan

-50 -25 0 25 50 75 100 125 150 175 2001.2

1.5

1.8

2.1

2.4

2.7

3.0

3.3

3.6

3.9e

α relaxation

γ relaxation

@ 103 Hz

Temperature (oC)

K

0.00

0.01

0.02

0.03

0.04

0.05

0.06

VK

XL-VK-1

XL-VK-2

XL-VK-3 tan

Fig. S9. Temperature-dependent dielectric spectra of the real part of permittivity (K) and loss

tangent (tan δ) of (a) VK, (b) XL-VK-1, (c) XL-VK-2, (d) XL-VK-3 at varied frequencies and (e)

VK and XL-VK at 103 Hz.

14

102

103

104

105

106

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0.18a

Imagin

ary

Part

of P

erm

ittivity

Frequency (Hz)

303 K 313 K

323 K 333 K

343 K 353 K

363 K 373 K

VK

102

103

104

105

106

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0.18b

303 K 313 K

323 K 333 K

343 K 353 K

363 K 373 K

XL-VK-1

Imagin

ary

Part

of P

erm

ittivity

Frequency (Hz)

102

103

104

105

106

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0.18c

303 K 313 K

323 K 333 K

343 K 353 K

363 K 373 K

XL-VK-2

Imagin

ary

Part

of P

erm

ittivity

Frequency (Hz)

102

103

104

105

106

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0.18d

303 K 313 K

323 K 333 K

343 K 353 K

363 K 373 K

XL-VK-3

Imagin

ary

Part

of P

erm

ittivity

Frequency (Hz)

Fig. S10. Frequency-dependent dielectric spectra of the imaginary part of permittivity of (a) VK,

(b) XL-VK-1, (c) XL-VK-2, (d) XL-VK-3 at varied temperatures.

15

6.1 6.2 6.3 6.4 6.5 6.6-4

-3

-2

-1

0

1a

Pro

babili

ty o

f F

ailu

re,

Plo

tted a

s: ln

(-ln

(1-P

))

VK

XL-VK-1

XL-VK-2

XL-VK-3

@ 25 oC

ln(Electric Field) (MV m-1)

5.2 5.4 5.6 5.8 6.0 6.2 6.4 6.6-4

-3

-2

-1

0

1b

Pro

babili

ty o

f F

ailu

re,

Plo

tted a

s: ln

(-ln

(1-P

))

VK

XL-VK-1

XL-VK-2

XL-VK-3

@ 100 oC


16

5.0 5.2 5.4 5.6 5.8 6.0 6.2 6.4 6.6-4

-3

-2

-1

0

1c

Pro

babili

ty o

f F

ailu

re,

Plo

tted a

s: ln

(-ln

(1-P

))

VK

XL-VK-1

XL-VK-2

XL-VK-3

@ 150 oC


Fig. S11. Weibull statistic of dielectric breakdown strength of VK and XL-VK at (a) 25 oC, (b)

100 oC and (c) 150 oC.

Table S2. Weibull parameters of VK and XL-VK at varied temperatures.

Sample 25 oC 100 oC 150 oC

Eb (MV m–1) β Eb (MV m–1) β Eb (MV m–1) β

VK 590 10.19 301 7.66 251 5.51

XL-VK-1 646 14.76 511 12.24 384 8.73

XL-VK-2 681 20.95 604 19.23 494 15.94

XL-VK-3 674 20.14 577 15.51 438 11.34

17

5.8 5.9 6.0 6.1 6.2 6.3 6.4 6.5 6.6 6.7-6

-5

-4

-3

-2

-1

0

1

Pro

babili

ty o

f F

ailu

re,

Plo

tted a

s: ln

(-ln

(1-P

))


VK

Eb = 590 MV m

-1

β = 10.19

c-BCB/

BNNSs

Eb = 447 MV m

-1

β = 13.96

c-BCB/

Al2O

3 NPLs

Eb = 500 MV m

-1

β = 15.37

PEI

Eb = 501 MV m

-1

β = 10.79

XL-VK-2

Eb = 681 MV m

-1

β = 20.95

Fig. S12. Room-temperature Weibull breakdown strengths of VK, XL-VK-2 and high-

temperature dielectric polymer and composite dielectrics including PEI, c-BCB/BNNSs and c-

BCB/Al2O3 NPLs.

18

Ul

Ue

Ele

ctr

ic D

ispla

cem

ent

Electric Field

Charge

Discharge

Uo = Ue + Ul

= Ue/Uo 100%

a

0 100 200 300 400 5000.000

0.003

0.006

0.009

0.012

0.015

0.018b

100 MV m-1

150 MV m-1

200 MV m-1

250 MV m-1

300 MV m-1

Ele

ctr

ic D

ispla

cem

ent (C

m-2)


VK @ 100 oC

0 100 200 300 400 5000.000

0.003

0.006

0.009

0.012

0.015

0.018c

100 MV m-1

200 MV m-1

300 MV m-1

400 MV m-1

500 MV m-1

XL-VK-1 @ 100 oC

E

lectr

ic D

ispla

cem

ent (C

m-2)


0 100 200 300 400 5000.000

0.003

0.006

0.009

0.012

0.015

0.018d

100 MV m-1

200 MV m-1

300 MV m-1

400 MV m-1

500 MV m-1

XL-VK-2 @ 100 oC

Ele

ctr

ic D

ispla

cem

ent (C

m-2)


0 100 200 300 400 5000.000

0.003

0.006

0.009

0.012

0.015

0.018e

100 MV m-1

200 MV m-1

300 MV m-1

400 MV m-1

500 MV m-1

XL-VK-3 @ 100 oC

Ele

ctr

ic D

ispla

cem

ent (C

m-2)


19

0 100 200 300 400 5000.000

0.003

0.006

0.009

0.012

0.015

0.018f

100 MV m-1

200 MV m-1

225 MV m-1

250 MV m-1

VK @ 150 oC

Ele

ctr

ic D

ispla

cem

ent (C

m-2)


0 100 200 300 400 5000.000

0.003

0.006

0.009

0.012

0.015

0.018g

100 MV m-1

200 MV m-1

300 MV m-1

350 MV m-1

XL-VK-1 @ 150 oC

Ele

ctr

ic D

ispla

cem

ent (C

m-2)


0 100 200 300 400 5000.000

0.003

0.006

0.009

0.012

0.015

0.018hXL-VK-2 @ 150

oC

Ele

ctr

ic D

ispla

cem

ent (C

m-2)


100 MV m-1

200 MV m-1

300 MV m-1

400 MV m-1

450 MV m-1

0 100 200 300 400 5000.000

0.003

0.006

0.009

0.012

0.015

0.018iXL-VK-3 @ 150

oC

Ele

ctr

ic D

ispla

cem

ent (C

m-2)


100 MV m-1

200 MV m-1

300 MV m-1

400 MV m-1

Fig. S13. (a) Schematic of electric displacement–electric field (D–E) loop of a dielectric material

with the discharged energy density (Ue) represented by the area in painted purple and energy

density loss (Ul) indicated by the area colored orange. The total stored energy density (Uo) equals

Ue plus Ul, and the charge–discharge efficiency (η) is calculated by η = Ue/Uo × 100%. The

conduction loss can be calculated as Ul/Uo ×100%. Unipolar D–E loops of VK, XL-VK-1, -2, and

-3 measured at 100 oC (b-e) and 150 oC (f-i), respectively.

20

0 100 200 300 400 500 600 700

0

1

2

3

4

5

6

7

8

9

10a

VK

XL-VK-1

XL-VK-2

XL-VK-3


Dis

charg

ed E

nerg

y D

ensity (

J c

m-3)

20

30

40

50

60

70

80

90

100

@ 25 oC

Charg

e-D

ischarg

e E

ffic

iency (

%)

0 100 200 300 400 500 600

0

1

2

3

4

5

6

7

8

VK

XL-VK-1

XL-VK-2

XL-VK-3

Electric Field (MV m-1)D

ischarg

ed E

nerg

y D

ensity (

J c

m-3)

-20

0

20

40

60

80

100b

Charg

e-D

ischarg

e E

ffic

iency (

%)

@ 100 oC

21

0 100 200 300 400 500

0

1

2

3

4

5

6

7

VK

XL-VK-1

XL-VK-2

XL-VK-3


ischarg

ed E

nerg

y D

ensity (

J c

m-3)

c

-40

-20

0

20

40

60

80

100

Charg

e-D

ischarg

e E

ffic

iency (

%)

@ 150 oC

Fig. S14. Discharged energy density and charge–discharge efficiency of VK and XL-VK at (a) 25 oC, (b) 100 oC and (c) 150 oC. Error bars represent standard deviations obtained from at least three

measurements using different samples.

22

80 100 120 140 160

0

2

4

6

8

c-BCB [12]

Epoxy resin [11]

Epoxy resin [11]

XL-VK-2

(This work)

Dis

ch

arg

ed

En

erg

y D

en

sity (

J c

m-3)

Temperature (oC)

XL-VK-2

(This work)

Fig. S15. Discharged energy density of XL-VK-2 and other crosslinked polymer dielectrics at

elevated temperatures.

23

0 100 200 300 400 500 600

0

1

2

3

4

5

6

7a

VK

VK/TAIC


ischarg

ed

Energ

y D

ensity (

J c

m-3)

0

10

20

30

40

50

60

70

80

90

100

@ 25 oC

Charg

e-D

ischarg

e E

ffic

iency (

%)

50 100 150 200 250

0.00

0.25

0.50

0.75

1.00

1.25

1.50

@ 150 oC

b

VK

VK/TAIC


ischarg

ed

Energ

y D

ensity (

J c

m-3)

-20

-10

0

10

20

30

40

50

60

70

80

90

100

Charg

e-D

ischarg

e E

ffic

iency (

%)

Fig. S16. Discharged energy density and charge–discharge efficiency of VK containing 5 wt%

TAIC measured at (a) 25 oC and (b) 150 oC. Error bars represent standard deviations obtained from

at least three measurements using different samples.

24

0 1 2 3 4 5 6 7 8 9 100.0

0.1

0.2

0.3

0.4

0.5a

Discharge time

BOPP @ 200 MV m-1

Dis

charg

ed E

nerg

y D

ensity (

J c

m-3)

Time (μs)

25 oC 1.47 μs

70 oC 1.46 μs

105 oC 1.41 μs

0 1 2 3 4 5 6 7 8 9 100.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

Dis

charg

ed E

nerg

y D

ensity (

J c

m-3)

Time (μs)

25 oC 1.48 μs

100 oC 1.48 μs

150 oC 1.52 μs

Discharge time

XL-VK-2 @ 200 MV m-1

b

Fig. S17. Discharged energy density of (a) BOPP and (b) XL-VK-2 at varied temperatures

measured at 200 MV m–1 as a function of discharge time.

25

The discharge time (t95%) is defined as the time for the discharge energy in a load resistor to reach

95% of the final value. Power density (P) is given as

95%

95%

UP

t= (S2)

where U95% is the discharged energy density recorded at the discharge time.

In a typical fast discharge test, the stored energy was discharged to a resistor RL in series with

the sample13. Since the various losses in a dielectric material should also be treated as an equivalent

series resistor (ESR), the energy discharged to RL (UR) is smaller than the total stored energy (Uo)

in the sample, as interpreted by the equation given as

o LR

L

*

ESR

U RU

R=

+ (S3)

But when the RL is much larger than the ESR, the discharged energy is very close to the stored

one. And also, ESR will depend on the discharge speed (or RL). In the frequency domain analysis,

tanESR( )

C

= (S4)

where ω is the angular frequency, and C is the capacitance. At the initial time of discharging (high

frequencies) to RL in which most of the energy is released, ESR effect is small. At later stage

(longer time and lower frequencies) of discharging process, ESR influence increases.

26

1 10 100 1000 100000.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8a@ 200 MV m

-1

Dis

ch

arg

ed

En

erg

y D

en

sity (

J c

m-3)

Cycle Number

XL-VK-2 @ 150 oC

BOPP @ 120 oC

0 100 200 300 400 500

0

1

2

3

4

5

6

7

8b

Origin

After cycles


ischarg

ed

Energ

y D

ensity (

J c

m-3)

0

10

20

30

40

50

60

70

80

90

100

@ 150 oC

Charg

e-D

dis

charg

e E

ffic

iency (

%)

Fig. S18. (a) Cyclic ability of BOPP at 120 oC and XL-VK-2 at 150 oC measured at 200 MV m–1.

XL-VK-2 shows almost no sign of degradation in Ue over a straight 50,000 cycles at 150 oC, while

BOPP is broken down at the 12,852 cycle at 120 oC.14 (b) Capacitive performance of XL-VK-2

before and after 50,000 cycling at 150 oC and 200 MV m–1.

27

10-14

10-13

10-12

10-11

10-10

10-9

10-8

a@ 25

oC

Cu

rre

nt

De

nsity (

A c

m-2)


VK

XL-VK-2

50 70 100 125 150

10-13

10-12

10-11

10-10

10-9

10-8

10-7

b @ 100 oC

Curr

ent D

en

sity (

A c

m-2)


VK

XL-VK-2

50 70 100 125 150

28

10-10

10-9

10-8

10-7

10-6

10-5

10-4

c @ 150 oC

VK

XL-VK-2

Curr

ent D

en

sity (

A c

m-2)


50 70 100 125 150

Fig. S19. Comparison of the conduction current density of VK and XL-VK-2 measured at varied

electric fields at (a) 25 oC, (b) 100 oC and (c) 150 oC. Error bars represent standard deviations

obtained from at least three measurements using different samples.

29

2064.89

1344.03

318.40251.46 235.69

10

100

1000

10000 PI

FPE

c-BCB/BNNSs

c-BCB/Al2O

3 NPLs

XL-VK-2

@ 150 oC

Incre

ase

Ratio

Fig. S20. Increase ratio of conduction current density of XL-VK-2 and high-temperature

dielectrics with the applied field at 400 MV m–1 vs. at 50 MV m–1 measured at 150 oC. The increase

ratio of conduction current density (Ri) was calculated by

hi

l

JR

J=

(S5)

where Jh is the conduction current density measured at relatively high electric field (i.e., 400 MV

m–1) and Jl is the conduction current density measured at relatively low electric field (i.e., 50 MV

m–1).

30

Table S3. TSDC results and calculated trap parameters

Sample Peak current

(×10-12 A)

Peak temperature

(Tm) (K)

Trap energy level

(eV)

Trapped charge

quantity (nC)

VK 1.11 144.50 0.57 0.86

XL-VK-1 5.90 158.30 0.89 5.76

XL-VK-2 15.27 160.20 1.03 13.12

XL-VK-3 20.66 154.50 0.96 17.64

0 1 2 3 40.0

0.2

0.4

0.6

0.8

1.0

1.2

Content of DCP (wt%)

Tra

p E

ne

rgy L

eve

l (e

V)

200

300

400

500

600

700

Eb (

MV

m-1)

@ 1

50

oC

Fig. S21. Weibull Breakdown Strength (Eb) at 150 oC and trap energy level calculated from TSDC

curve of VK and XL-VK as a function of DCP content. Error bars represent standard deviations

obtained from at least three measurements using different samples. The formation of deepest traps

and its high-temperature peak location at ~160 °C for XL-VK-2 could be responsible for the

improved dielectric breakdown strength up to 150 °C since15,16

TSDC

b

B

exp( )4

AE

K T

(S6)

where ATSDC is the trap energy level, KB is the Boltzmann constant. Charges need to overcome a

potential barrier after being trapped, the bigger the trap energy becomes, the stronger the trapping

effect is. It is difficult for the trapped carriers in deeper traps to escape (de-trap), thus leading to

the decreased carrier mobility and the improvement of breakdown strength.

31

-40 0 40 80 120 160 200 240-3

-2

-1

0

1

2

3

1 min 5 min

10 min 20 min

40 min 60 min

Ch

arg

e D

ensity (

C m

-3)

Position (μm)

VK

@ 25 oC

a

-40 0 40 80 120 160 200 240-1.2

-0.8

-0.4

0.0

0.4

0.8

1.2

1 min 5 min

10 min 20 min

40 min 60 min

b XL-VK-2

@ 25 oC

Charg

e D

ensity (

C m

-3)

Position (μm)

32

-40 0 40 80 120 160 200 240-5

-4

-3

-2

-1

0

1

2

3

4

5

1 min 5 min

10 min 20 min

40 min 60 min

cVK

@ 80 oC

Ch

arg

e D

ensity (

C m

-3)

Position (μm)

-40 0 40 80 120 160 200 240-9

-6

-3

0

3

6

9

1 min 5 min

10 min 20 min

40 min 60 min

d XL-VK-2

@ 80 oC

Charg

e D

ensity (

C m

-3)

Position (μm)

Fig. S22. Charge decay profiles of VK and XL-VK-2 at 25 oC (a,b) and 80 °C (c,d), respectively.

33

101

102

103

0.0

0.1

0.2

0.3

0.4

0.5

0.6

@ 25 oC

VK

XL-VK-2

a

Avera

ge C

harg

e D

ensity (

C m

-3)

Time (s)

101

102

103

0.85

0.90

0.95

1.00

1.05

1.10 @ 25 oC

VK

XL-VK-2

b

Tra

p D

epth

(eV

)

Time (s)

34

101

102

103

10-17

10-16

10-15

10-14

10-13

10-12

10-11

@ 25 oC

VK

XL-VK-2

c

Appare

nt M

obili

ty (

m2 V

-1 s

-1)

Time (s)

Fig. S23. (a) Average charge density, (b) Trap depth, and (c) Apparent mobility of VK and XL-

VK-2 as a function of decay time at 25 oC, respectively. Error bars represent standard deviations

obtained from at least three measurements using different samples.

35

Supplementary References

1. A. Taguet, B. Ameduri and B. Boutevin, Adv. Polym. Sci., Springer Press, New York, 2005,

127.

2. D. J. T. Hill, K. J. Thurecht and A. K. Whittaker, Radiat. Phys. Chem., 2003, 67, 729.

3. Y. Suzuoki, K. Yasuda, T. Mizutani and M. Ieda, J. Phys. D Appl. Phys., 1977, 10, 1985.

4. Y. Takai, K. Mori, T. Mizutani and M. Ieda, Jpn. J. Appl. Phys., 1976, 15, 2341.

5. C. Y. Liang and S. Krimm, J. Chem. Phys., 1956, 25, 563.

6. A. Soldera, Macromolecular Symposia, WILEY‐VCH Verlag GmbH & Co. KGaA,

Weinheim, 1998, 11.

7. A. M. Bueche, J. Am. Chem. Soc., 1952, 74, 65.

8. N. S. Murthy, Y. P. Khanna and A. J. Signorelli, Polym. Eng. Sci., 1994, 34, 1254.

9. P. Starck, Polym. Int., 1996, 40, 111.

10. P. Khanchaitit, K. Han, M. R. Gadinski, Q. Li and Q. Wang, Nat. Commun., 2013, 4, 2845.

11. S. Chen, G. Meng, B. Kong, B. Xiao, Z. Wang, Z. Jing, Y. Gao, G. Wu, H. Wang and Y.

Cheng, Chem. Eng. J., 2020, 387, 123662.

12. Q. Li, L. Chen, M. R. Gadinski, S. Zhang, G. Zhang, H. U. Li, E. Iagodkine, A. Haque, L.

Q. Chen, T. Jackson and Q. Wang, Nature, 2015, 523, 576.

13. Q. Li, K. Han, M. R. Gadinski, G. Zhang and Q. Wang, Adv. Mater., 2014, 26, 6244.

14. H. Li, L. Ren, D. Ai, Z. Han, Y. Liu, B. Yao and Q. Wang, InfoMat, 2020. DOI:

10.1002/inf2.12043.

15. S. J. Wang, J. W. Zha, W. K. Li and Z. M. Dang, Appl. Phys. Lett., 2016, 108, 092902.

16. S. Li, D. Xie, G. Qu, L. Yang, D. Min and Y. Cheng, Appl. Surf. Sci., 2019, 478, 451.

Electronic Supplementary Information · XL-VK-1 VK: Temperature (o C) Fig. S7. DSC curves collected...

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Transcript of Electronic Supplementary Information · XL-VK-1 VK: Temperature (o C) Fig. S7. DSC curves collected...