Supplemental Material
High Electric Energy Storage Density of Poly(vinylidene
fluoride) in -Form Crystal Domain
Wenjing Li, Yuansuo Zheng, Zhicheng Zhang a)
Department of Applied Chemistry, School of Science, MOE Key Laboratory for
Nonequilibrium Synthesis and Modulation of Condensed Matter, Xi’an Jiaotong
University, Xi’an, China, 710049
Weimin Xia, Zhuo Xu
Electronic Materials Research Laboratory, Key Laboratory of Ministry of Education,
Xi’an Jiaotong University, Xi’an 710049, China
1. FTIR of -, β- and -PVDF films
In -PVDF film, the -phase could be confirmed by the characteristic absorption
bands at 408, 532, 614, 764, 796, 855, and 976 cm-1. The small peak at about 840 cm-1
may attributed to -phase in minority. The absorption bands at 431, 512, 776, 812, 833,
and 840 cm-1 observed in -PVDF film are characteristic -phase PVDF, which
confirms the majority of -phase crystal in this film. The bands at 444 and 510 cm-1
are regarded as characteristic of the β phase, which is distinguished from -PVDF1.
All the information indicates that the samples applied possess the majority of the
corresponding crystal phase as desired.

840
773
Transmittance

605
433
812
512
484

445
410
855
1423
1600
1393
1400
795
975
1280
1150 1070
1200
1000
877
765
800
530
615 490
600
400
-1
Wave Number(cm )
FIG S1. FTIR and assignment of PVDF in -, β- and -form crystal phase
2. XRD and DSC of - and -PVDF films treated in different thermal
process
- and -PVDF films are treated in different thermal processes including
solution casting as received marked as untreated, quenching from 200 oC to ice-water
immediately marked as quenched and cooling from 200oC gradually to room
temperature in 24 hours marked as annealed. The XRD results and the assignment are
presented in Fig. S1. The results indicate that different thermal treatment processes
exhibit limited influence on the crystal forms of the films. DSC results are shown in
Fig. S2. Annealing may improve the crystallinity of the films slightly. However,
quenching is able to reduce the crystallinity of PVDF films greatly.
-PVDF
20.2
(021)
17.94
(100)
26.8
(022)
1 untreated
2 quenched
3 annealed
27.92
(100)
-PVDF
20.1
(110)
PVDF 40
18.5
(020)
38.7
(211)
39
(002)
36.12
(200)
1
I/I0
I/I0
3
1 untreated
2 quenched
3 annealed
2
2
18.4
(020)
39
(002)
15
20
25
30
35
40
1
45
3
50
0
10
20
30
40
50
60

o
2 ( )
FIG S2. XRD and assignment of - and -PVDF films treated in different thermal
process.
175
-PVDF
quenched
annealed
untreated
172
60.3J/g
58.6J/g
174
-PVDF
Heat Flow(a.u.)
Heat Flow
annealed
untreated
quenched
173
173
44J/g
56J/g
39.8J/g
40
60
80
100
120
140
Temperature(C)
175
53J/g
160
180
200
20
40
60
80
100
120
140
160
180
200
Temperature(C)
FIG S3. DSC of - and -PVDF films treated in different thermal process.
3. Dielectric constant () and loss (tan) of - and -PVDF films
treated in different thermal process
As shown in Fig. S3, thermal treatment leads to significant influence on the
dielectric properties of -PVDF. Both the dielectric constant and loss of the three
samples are in the order of quenched film>untreated film>annealed film, which is in
the same order of H or the crystallinity of the corresponding samples observed from
DSC. It is well known that the dielectric constant and loss in low electric field is more
related to the noncrystaline phase of the sample. The similar results are observed in
-PVDF as well. Apparently, quenching leads to a lower crystallinity therefore higher
dielectric response, and annealing favors the crystalline phase therefore low dielectric
response.
16
0.5
Annealed
Untreated
Quenched
14
12
0.5
0.4
0.4
8
10
0.3
r'
(Untreated)
(Quenched)
4
0.2
0.1
4
-PVDF
2
0
2
10
3
10
4
10
5
2
0.0
0
2
10
0.0
6
10
0.1
7
10
10
3
10
4
5
10
Frequency(Hz)
10
6
10
7
10
8
10
Frequecy(Hz)
FIG S4. Dielectric constant () and loss (tan) of -PVDF treated in different
processes.
4. XRD of quenched -PVDF film and -PVDF film after poled in an
electric field beyond 300MV/m
XRD results of the quenched -PVDF and poled -PVDF in the electric field
beyond 300MV/m are shown in Fig. S4. All the reflections of the poled -PVDF
coincide perfectly with the quenched -PVDF, which confirms the phase transition of
- to -PVDF induced by the electric field.
I/I0
1 quenched -PVDF
2 poled -PVDF
1
2
10
20
30
40
50
60

2
FIG S5. XRD comparison of quenched -PVDF and poled -PVDF in the electric
field beyond 300MV/m.
5. Unipolar D-E hysteresis loops of β-PVDF measured in the
tan
0.2
6
0.3
6
tan
8
r'
-PVDF
10
increasing electric field.
The D-E hysteresis loops of uniaxially stretched β-PVDF are measured in the
increasing electric field as shown in Fig. S5. As electric field increases, the loops
expand in parallel with each other gradually. All the loops are very slim.
2
Displacement (C/m )
0.04
-PVDF
0.03
0.02
0.01
0.00
0
50
100
150
200
E(MV/m)
FIG S6. Unipolar D-E loops of β-PVDF as a function of electric field.