Electronic Supplementary Information

High rate capability supercapacitors assembled from wet-spun

graphene films with CaCO3 template

Tieqi Huang,a Bingna Zheng,a Zheng Liu,a Liang Koua and Chao

Gao*a

a MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, 38 Zheda Road, Hangzhou 310027, P. R. China.*Email: chaogao@zju.edu.cn

Electronic Supplementary Material (ESI) for Journal of Materials Chemistry A.This journal is © The Royal Society of Chemistry 2014

Experimental

Materials: All the reagents were of analytical grade and used as received. GO was prepared

according to a modified Hummers’ method from natural graphite as previously reported.1

Preparation of WGF: As shown in Figure 1, WGF was prepared by wet-spinning of GO liquid

crystalline dope (10 mg/mL) into a coagulation bath (CaCl2 5 wt %, ethanol: H2O = 1:3), followed

by growth of calcite crystals in a crystallization bath contained 5 wt % Na2CO3 aqueous solution,

chemical reduction of GO by 20 wt% hydrazine hydrate at 85 oC, and etching of calcite with 1 M

HCl.

Preparation of GF: The control film of GF was prepared by wet-spinning of GO liquid

crystalline dope (10 mg/mL) into a coagulation bath (CaCl2 5 wt %, ethanol: H2O = 1:3), followed

by washing with pure water and then chemical reduction of GO by 20 wt% hydrazine hydrate at

85 oC.

Preparation of pWGF and pGF: 0.039 g aniline was dropped in a flask, which contained 5 mL

ethanol and 15 mL 1 M perchloric acid. It was stirred for half an hour before WGFs were dipped

in. After 1 h, 0.063 g ammonium persulfate in 5 mL perchloric acid was added to the flask

dropwise. The reaction was kept at -10 oC without stirring for 24 h. Then the films were washed

with 0.1 M perchloric acid to obtain pWGFs. Using GFs to replace WGFs, pGFs were prepared

with the same protocol as the case of pWGFs.

Characterization: SEM and EDS were conducted on Hitachi S-4800. XRD was measured by

Rigaku D/max-2500, using graphite monochromatized CuK α radiation. Electrochemical

measurements were carried out in cells with two symmetrical electrodes, using a mixed cellulose

esters membrane as separator (pore size 0.22μm), platinum foils as current collector, and 1 M

H2SO4 as electrolyte. CV, GC and EIS tests were performed using an electrochemical workstation

(CHI660e, CH Instruments, Inc.). Mechanical property tests were carried on a HS-3002C at a

loading rate of 10% per minute. Nitrogen cryoadsorption was measured by AUTOSORB-IQ-MP

(Quantachrome Inc., USA) and the sample was outgassed under vacuum at 150oC for 1 h before

measurement. The SSA was obtained by Brunauer-Emmett-Teller (BET) analyses of the

adsorption isotherm. Total pore volume was calculated from the N2 adsorption amount at P/P0 =

0.99.

1 Z. Xu, C. Gao, ACS Nano 2011, 5, 2908.

Tables:

Table S1. Comparison of rate performance. (HI: high current density tested by the specific

authors)

Preparation method HI

(A/g)

SC of the

author at HI

SC retention of

the author at HI

SC of our

work at HI

SC retention of

our work at HI

Ni foam based GF-SC1 10 105 84% 170 96%

GF-SC gel2 100 120 75% 140 79%

GF-SC+CNT3 50 130 52% 152 86%

MgO model GF-SC4 25 208 85% 152~164 86%~93%

Carbon nanocage5 100 112 52% 140 79%

GF-SC wet paper6 100 175 81% 140 79%

GF-SC wet foam7 100 110 64% 140 79%

Anti-solvant GF-SC8 30 171 72% 152~164 86%~93%

Vertically bridging GF-SC9 100 155 88% 140 79%

GF-SC compact wet paper10 100 145 69% 140 79%

SiO2 model GF-SC11 18 136 85% 164~170 93%~96%

PIL-GF-SC12 8 127 68%

Comparison

172 97%

Table S2. Comparison of rate capability of supercapacitors with pseudocapacitance. (HI: high current density tested by the specific authors)

Materials SC at 1A/g

(F/g)

HI (A/g) SC retention at HI

20 100%

50 96%pWGF of this work 505

100 90%

PANI-RGO13 200 10 77%

PANI-RGO14 245 20 86%

PANI-RGO15 362 10 95%

PANI-RGO16 241 30 83%

1 H. Huang, L. Xu, Y. Tang, S. Tang, Y. Du, Nanoscale 2014, 6, 2426.2 U. N. Maiti, J. Lim, K. E. Lee, W. J. Lee, S. O. Kim, Adv. Mater. 2014, 26, 615.3 X. Lu, H. Dou, B. Gao, C. Yuan, S. Yang, L. Hao, L. Shen, X. Zhang, Electrochim. Acta 2011,

56, 5115.4 G. Ning, Z. Fan, G. Wang, J. Gao, W. Qian, F. Wei, Chem. Commun. 2011, 47, 5976.5 K. Xie, X. Qin, X. Wang, Y. Wang, H. Tao, Q. Wu, L. Yang, Z. Hu, Adv. Mater. 2012, 24, 347.6 X. Yang, J. Zhu, L. Qiu, D. Li, Adv. Mater. 2011, 23, 2833.7 F. Liu, S. Song, D. Xue, H. Zhang, Adv. Mater. 2012, 24, 1089.8 Y. Yoon, K. Lee, C. Baik, H. Yoo, M. Min, Y. Park, S. M. Lee, H. Lee, Adv. Mater. 2013, 25,

4437.9 Z. Bo, W. Zhu, W. Ma, Z. Wen, X. Shuai, J. Chen, J. Yan, Z. Wang, K. Cen, X. Feng, Adv.

Mater. 2013, 25, 5799.10 X. Yang, C. Cheng, Y. Wang, L. Qiu, D. Li, Science 2013, 341, 534.11 Y. Korenblit, M. Rose, E. Kockrick, L. Borchardt, A. Kvit, S. Kaskel, G. Yushin, ACS Nano

2010, 4, 1337.12 T. Y. Kim, H. W. Lee, M. Stoller, D. R. Dreyer, C. W. Bielawski, R. S. Ruoff, K. S. Suh, ACS

Nano 2010, 5, 436.13 J. H. Lee, N. Park, B. G. Kim, D. S. Jung, K. Im, J. Hur, J. W. Choi, ACS Nano 2013, 7, 9366.14 J. Benson, I. Kovalenko, S. Boukhalfa, D. Lashmore, M. Sanghadasa, G. Yushin, Adv.

Mater. 2013, 25, 6625.15 Y. Meng, K. Wang, Y. Zhang, Z. Wei, Adv. Mater. 2013, 25, 6985.

16 H. Cao, X. Zhou, Y. Zhang, L. Chen, Z. Liu, J. Power Sources 2013, 243, 715.

Calculations：

(1) The specific capacitance calculated by CV:

2 1( )s

IdUC

m u U U

Ñ

Where Cs (F/g), m (g), u (V/s), U2 and U1 (V), and I (A) are the gram specific capacitance, the

weight of single electrode, scan rate, high and low potential limit of CV tests, and the instant

current of CV curves, respectively.

(2) The specific capacitance calculated by GC:

2s

I tCm U

Where Cs (F/g), I (A), t (s), ΔU (V), and m (g) are the gram specific capacitance, the discharge

current, the discharge time, the potential window and the weight of single electrode,

respectively.

(3) The volume capacitance and area capacitance are calculated as followed:

sv

C mCV

sa

C mCA

Where A (cm2), V (cm3), and m (g) are surface area of one electrode, volume of one electrode

and weight of on electrode, respectively.

Figures:

Figure S1. EDS images of CaCO3-GF.

Figure S2. SEM images of WGF and its corresponding carbon.

Figure S3. SEM images of GF in three different magnifications.

0.0 0.2 0.4 0.6 0.8-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

Curre

nt d

ensi

ty /

(A*g

-1)

Potential / V

WGF-SC GF-SC

Figure S4. Comparison of the CV curves of WGF-SC and GF-SC, the scan rate is 10 mV/s.

0 50 100 150

0.0

0.2

0.4

0.6

0.8

Pote

ntia

l / V

Time / s

WGF-SC GF-SC

Figure S5. Comparison of the GC curves of WGF-SC and GF-SC, the current density is 1 A/g.

0 2000 4000 6000 8000 100000.0

0.2

0.4

0.6

0.8

1.0

C s / C

0

Cycle number

Figure S6. Stability of WGF-SC, the current density is 10 A/g. (C0: the initial Cs of first test cycle)

0 5 10 15 20 25 30

0.000

0.001

0.002

0.003

0.004

0.005

dv(D

)

Diameter / nm

WGF

Figure S7. Pore distribution of WGF.

0 5 10 15 20 25 30

0.0000

0.0005

0.0010

0.0015

0.0020

0.0025

0.0030

dV(D

)

Diameter / nm

GF

Figure S8. Pore distribution of GF.

Figure S9. SEM image of pWGF.

0 100 200 300 400 500 6000.0

0.2

0.4

0.6

0.8

Pote

ntia

l / V

Time / s

pWGF-SC pGF-SC

Figure S10. Comparison of the GC curves of pWGF-SC and pGF-SC at the current density of 1 A/g.

0 1 2 30.0

0.2

0.4

0.6

0.8

Pote

ntia

l / V

Time / s

pWGF-SC pGF-SC

0.13V 0.06V

Figure S11. Comparison of the GC curves of pWGF-SC and pGF-SC at the current density of 100 A/g.

0 5 10 15 20 250

5

10

15

20

25

-Z''/o

hm

Z'/ohm

pWGF-SC

Figure S12. EIS of pWGF-SC.

Figure S13. SEM of pGF.

0 1000 2000 3000 4000 50000.0

0.2

0.4

0.6

0.8

1.0

C s /

C 0

Cycle number

Figure S14. Stability of pWGF-SC, the current density is 10 A/g. (C0: the initial CS of first test cycle)