Supporting Information for Omnidirectionally Stretchable High ...
Supporting Information for Omnidirectionally Stretchable High Performance Supercapacitor Based on Isotropic Buckled Carbon Nanotube Films Jiali Yu†,‡, Weibang Lu∥, Shaopeng Pei‡, Ke Gong§, Liyun Wang‡, Linghui Meng†, Yudong Huang*,†, Joseph P. Smith⊥, Karl S. Booksh⊥, Qingwen Li∥, Joon-Hyung Byun#, Youngseok Oh#, Yushan Yan§, and Tsu-Wei Chou*,‡
†
School of Chemical Engineering and Technology, Harbin Institute of Technology,
Harbin, 150001, P.R. China ‡
Department of Mechanical Engineering, §Department of Chemical and Biomolecular
Engineering, Center for Catalytic Science and Technology, and
⊥Department
of
Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, United States ∥Suzhou
Institute of Nano-Tech and Nano-Bionics, Suzhou 215123, P. R. China
Composites Research Center, Korean Institute of Materials Science, Changwon,
#
641831, South Korea
S1
Figure S1. TEM image of a bundle of CNTs.
250
Stress (MPa)
200 150 100 50 0 0
5
10
15
20
Strain (%) Figure S2. Stress-strain curve of a typical CNT film. The tensile elongation rate was 1.5 mm min-1.
S2
Figure S3. Schematic illustration of steps for fabricating omnidirectionally stretchable CNT film. A schematic illustration of the fabrication process for constructing a buckled CNT film is given in Figure S3. Here, a stretchable silicon rubber film was first prepared by mixing a silicone-elastomer base with a curing agent. Then, the silicon rubber substrate was uniformly pre-stretched to certain strain levels in all directions. The CNT film was subsequently transferred and attached to the prestretched substrate. Thereafter, the prestrains in the substrate were relaxed. During relaxation, the lateral dimensions of the CNT film were reduced in proportional to those of the substrate. By simply adjusting the prestrain level of a substrate, buckled CNT films with different omnidirectional stretchabilities in the range of 50%-200% can be readily obtained.
S3
Figure S4. (a) Buckled structure (omnidirectional prestrain=200%) formed under sequential conpression (in the x-direction first and then in all other directions). (b) Enlarged view of (a). (c) Side view of (a).
S4
Figure S5. Reversible unbuckling-buckling of a CNT film under uniaxial stretching-releasing of the polymer substrate. Optical microscopic images of the buckled CNT film (omnidirectional prestrain=200%) under various uniaxial stretching strains: 0%, 50%, 100%, 150%, 200%, and 0%.
S5
Figure S6. Reversible unbuckling-buckling of a CNT film by omnidirectional stretching strain in the CNT film through stretching-releasing the polymer substrate. Optical microscopic images of the buckled CNT film (omnidirectional prestrain=200%) under various omnidirectional stretching strains: 0%, 50%, 100%, 150%, 200%, and then released to 0%.
S6
CNT film
Substrate
CNT film Substrate
CNT film
Substrate
Figure S7. (a) SEM images of buckled CNT film/silicon rubber cut by focused ion beam. (b, c) Enlarged views of the marked areas in (a). (d) SEM image of side view of buckled CNT film on silicon rubber substrate. (e) Enlarged view of the marked area in (d).
S7
Figure S8. Peeling of buckled CNT film (omnidirectional prestrain=200%) from silicon rubber substrate.
To verify good interfacial bonding between the CNT film and the substrate, the interface between buckled CNT film and substrate was examined using an integrated focused ion beam (FIB) and SEM system. Both the central (Figure S7a) and side areas (Figure S7d) of the buckled CNT film remained perfectly attached to the substrate. Furthermore, a thin layer of CNTs was still attached to the substrate when the buckled
Sheet resistance ( sq-1)
CNT film was peeled from the substrate (Figure S8).
4.0 3.5 3.0 2.5 2.0 1.5 1.0
20 30 40 50 60 70 80
90 100
o
Tempreture ( C)
S8
Figure S9. The variation of electrical conductivity of CNT film in the temperature range of 20 ℃ to 100 ℃.
Figure S10. (a) CV curves of buckled acid treated CNT@PANI film at different deposition time. The CV curves were tested using three-electrode system in 1 M H2SO4 aqueous solution at a scan rate of 20 mV s-1. (b) Normalized areal specific capacitance (where C0 represents the areal specific capacitance of buckled acid treated CNT film and C represents the areal specific capacitance of buckled acid treated CNT@PANI film at different deposition times) and PANI weight percentage versus deposition times.
S9
Figure S11. SEM images of the acid treated CNT@PANI films at different deposition times (a) 100 s, (b) 150 s, (c) 200 s, and (d) 250 s.
Figure S12. CV curves of isotropic buckled acid treated CNT film based stretchable supercapacitor.
S10
Figure S13. CV curves of isotropic buckled CNT@PANI film based stretchable supercapacitor.
400 350
Cm (F g-1)
300
CNT Acid treated CNT CNT@PANI Acid treated CNT@PANI
250 200 150 100 50 0
0
50
100
150
200
Scan rate (mV s-1) Figure S14. Variations of gravimetric specific capacitance with scan rate for different samples.
S11
Figure S15. SEM images of the buckled acid treated CNT@PANI film before (a) and after (b) 20 omnidirectional stretching cycles. The insets exhibit the enlarged views.
Table S1. Comparison of the isotropic buckled CNT film electrodes with the other reported stretchable conductors.1-8 Stretchable Conductor
Sheet Resistance (Ω sq-1)
Conductivity (S cm-1)
Normalized Resistance R/R0
Strain (%)
Ref.
Doped SWCNT film/PDMSa
328
-
~5
150
1
Superaligned MWCNT ribbon/PDMSb
211
-
~1.6
100
2
Superaligned CNT/PDMS
650
-
~1.06
100
3
CVD graphene/PDMSc
-
600-1250
~25
40
4
SWCNT macrofilms/PDMS
-
-
~3.3
70
5
2000
1.05
140
6
-
~1.8
30
7
SWCNT film/PDMS Highly aligned CNT sheet/PDMS
-
S12
SWCNT/polymer composite
50-500
Isotropic buckled CNT/PDMS
2.75
3636
~1.5-2.4
50
8
~1.03
200
Present Work
a)
SWCNT: single-walled carbon nanotube; b)MWCNT: multi-walled carbon nanotube; c) CVD: chemical vapor deposition. REFERENCES 1. . Lipomi, D. J.; Vosgueritchian, M.; Tee, B. C.; Hellstrom, S. L.; Lee, J. A.; Fox, C. H.; Bao, Z. Skin-like Pressure and Strain Sensors Based on Transparent Elastic Films of Carbon Nanotubes. Nat. Nanotechnol. 2011, 6, 788–792. 2. Zhu, Y.; Xu, F. Buckling of Aligned Carbon Nanotubes as Stretchable Conductors: A New Manufacturing Strategy. Adv. Mater. 2012, 24, 1073–1077. 3. Shin, U.-H.; Jeong, D.-W.; Kim, S.-H.; Lee, H. W.; Kim, J.-M. ElastomerInfiltrated Vertically Aligned Carbon Nanotube Film-Based Wavy-Configured Stretchable Conductors. ACS Appl. Mater. Interfaces 2014, 6, 12909–12914. 4. Chen, T.; Xue, Y.; Roy, A. K.; Dai, L. Transparent and Stretchable HighPerformance Supercapacitors Based on Wrinkled Graphene Electrodes. ACS Nano 2013, 8, 1039– 1046. 5. Yu, C.; Masarapu, C.; Rong, J.; Wei, B.; Jiang, H. Stretchable Supercapacitors Based on Buckled Single-Walled Carbon-Nanotube Macro-films. Adv. Mater. 2009, 21, 4793-4797. 6. Niu, Z.; Dong, H.; Zhu, B.; Li, J.; Hng, H. H.; Zhou, W.; Chen, X.; Xie, S. Highly Stretchable, Integrated Supercapacitors Based on Single-Walled Carbon Nanotube Films with Continuous Reticulate Architecture. Adv. Mater. 2013, 25, 1058−1064.
S13
7. Chen, T.; Peng, H.; Durstock, M.; Dai, L. High-Performance Transparent and Stretchable All-Solid Supercapacitors Based on Highly Aligned Carbon Nanotube Sheets. Sci. Rep. 2014, 4, 03612. 8. Yu, Z.; Niu, X.; Liu, Z.; Pei, Q. Intrinsically Stretchable Polymer Light-Emitting Devices Using Carbon Nanotube Polymer Composite Electrodes. Adv. Mater. 2011, 23, 3989–3994.
S14
†
School of Chemical Engineering and Technology, Harbin Institute of Technology,
Harbin, 150001, P.R. China ‡
Department of Mechanical Engineering, §Department of Chemical and Biomolecular
Engineering, Center for Catalytic Science and Technology, and
⊥Department
of
Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, United States ∥Suzhou
Institute of Nano-Tech and Nano-Bionics, Suzhou 215123, P. R. China
Composites Research Center, Korean Institute of Materials Science, Changwon,
#
641831, South Korea
S1
Figure S1. TEM image of a bundle of CNTs.
250
Stress (MPa)
200 150 100 50 0 0
5
10
15
20
Strain (%) Figure S2. Stress-strain curve of a typical CNT film. The tensile elongation rate was 1.5 mm min-1.
S2
Figure S3. Schematic illustration of steps for fabricating omnidirectionally stretchable CNT film. A schematic illustration of the fabrication process for constructing a buckled CNT film is given in Figure S3. Here, a stretchable silicon rubber film was first prepared by mixing a silicone-elastomer base with a curing agent. Then, the silicon rubber substrate was uniformly pre-stretched to certain strain levels in all directions. The CNT film was subsequently transferred and attached to the prestretched substrate. Thereafter, the prestrains in the substrate were relaxed. During relaxation, the lateral dimensions of the CNT film were reduced in proportional to those of the substrate. By simply adjusting the prestrain level of a substrate, buckled CNT films with different omnidirectional stretchabilities in the range of 50%-200% can be readily obtained.
S3
Figure S4. (a) Buckled structure (omnidirectional prestrain=200%) formed under sequential conpression (in the x-direction first and then in all other directions). (b) Enlarged view of (a). (c) Side view of (a).
S4
Figure S5. Reversible unbuckling-buckling of a CNT film under uniaxial stretching-releasing of the polymer substrate. Optical microscopic images of the buckled CNT film (omnidirectional prestrain=200%) under various uniaxial stretching strains: 0%, 50%, 100%, 150%, 200%, and 0%.
S5
Figure S6. Reversible unbuckling-buckling of a CNT film by omnidirectional stretching strain in the CNT film through stretching-releasing the polymer substrate. Optical microscopic images of the buckled CNT film (omnidirectional prestrain=200%) under various omnidirectional stretching strains: 0%, 50%, 100%, 150%, 200%, and then released to 0%.
S6
CNT film
Substrate
CNT film Substrate
CNT film
Substrate
Figure S7. (a) SEM images of buckled CNT film/silicon rubber cut by focused ion beam. (b, c) Enlarged views of the marked areas in (a). (d) SEM image of side view of buckled CNT film on silicon rubber substrate. (e) Enlarged view of the marked area in (d).
S7
Figure S8. Peeling of buckled CNT film (omnidirectional prestrain=200%) from silicon rubber substrate.
To verify good interfacial bonding between the CNT film and the substrate, the interface between buckled CNT film and substrate was examined using an integrated focused ion beam (FIB) and SEM system. Both the central (Figure S7a) and side areas (Figure S7d) of the buckled CNT film remained perfectly attached to the substrate. Furthermore, a thin layer of CNTs was still attached to the substrate when the buckled
Sheet resistance ( sq-1)
CNT film was peeled from the substrate (Figure S8).
4.0 3.5 3.0 2.5 2.0 1.5 1.0
20 30 40 50 60 70 80
90 100
o
Tempreture ( C)
S8
Figure S9. The variation of electrical conductivity of CNT film in the temperature range of 20 ℃ to 100 ℃.
Figure S10. (a) CV curves of buckled acid treated CNT@PANI film at different deposition time. The CV curves were tested using three-electrode system in 1 M H2SO4 aqueous solution at a scan rate of 20 mV s-1. (b) Normalized areal specific capacitance (where C0 represents the areal specific capacitance of buckled acid treated CNT film and C represents the areal specific capacitance of buckled acid treated CNT@PANI film at different deposition times) and PANI weight percentage versus deposition times.
S9
Figure S11. SEM images of the acid treated CNT@PANI films at different deposition times (a) 100 s, (b) 150 s, (c) 200 s, and (d) 250 s.
Figure S12. CV curves of isotropic buckled acid treated CNT film based stretchable supercapacitor.
S10
Figure S13. CV curves of isotropic buckled CNT@PANI film based stretchable supercapacitor.
400 350
Cm (F g-1)
300
CNT Acid treated CNT CNT@PANI Acid treated CNT@PANI
250 200 150 100 50 0
0
50
100
150
200
Scan rate (mV s-1) Figure S14. Variations of gravimetric specific capacitance with scan rate for different samples.
S11
Figure S15. SEM images of the buckled acid treated CNT@PANI film before (a) and after (b) 20 omnidirectional stretching cycles. The insets exhibit the enlarged views.
Table S1. Comparison of the isotropic buckled CNT film electrodes with the other reported stretchable conductors.1-8 Stretchable Conductor
Sheet Resistance (Ω sq-1)
Conductivity (S cm-1)
Normalized Resistance R/R0
Strain (%)
Ref.
Doped SWCNT film/PDMSa
328
-
~5
150
1
Superaligned MWCNT ribbon/PDMSb
211
-
~1.6
100
2
Superaligned CNT/PDMS
650
-
~1.06
100
3
CVD graphene/PDMSc
-
600-1250
~25
40
4
SWCNT macrofilms/PDMS
-
-
~3.3
70
5
2000
1.05
140
6
-
~1.8
30
7
SWCNT film/PDMS Highly aligned CNT sheet/PDMS
-
S12
SWCNT/polymer composite
50-500
Isotropic buckled CNT/PDMS
2.75
3636
~1.5-2.4
50
8
~1.03
200
Present Work
a)
SWCNT: single-walled carbon nanotube; b)MWCNT: multi-walled carbon nanotube; c) CVD: chemical vapor deposition. REFERENCES 1. . Lipomi, D. J.; Vosgueritchian, M.; Tee, B. C.; Hellstrom, S. L.; Lee, J. A.; Fox, C. H.; Bao, Z. Skin-like Pressure and Strain Sensors Based on Transparent Elastic Films of Carbon Nanotubes. Nat. Nanotechnol. 2011, 6, 788–792. 2. Zhu, Y.; Xu, F. Buckling of Aligned Carbon Nanotubes as Stretchable Conductors: A New Manufacturing Strategy. Adv. Mater. 2012, 24, 1073–1077. 3. Shin, U.-H.; Jeong, D.-W.; Kim, S.-H.; Lee, H. W.; Kim, J.-M. ElastomerInfiltrated Vertically Aligned Carbon Nanotube Film-Based Wavy-Configured Stretchable Conductors. ACS Appl. Mater. Interfaces 2014, 6, 12909–12914. 4. Chen, T.; Xue, Y.; Roy, A. K.; Dai, L. Transparent and Stretchable HighPerformance Supercapacitors Based on Wrinkled Graphene Electrodes. ACS Nano 2013, 8, 1039– 1046. 5. Yu, C.; Masarapu, C.; Rong, J.; Wei, B.; Jiang, H. Stretchable Supercapacitors Based on Buckled Single-Walled Carbon-Nanotube Macro-films. Adv. Mater. 2009, 21, 4793-4797. 6. Niu, Z.; Dong, H.; Zhu, B.; Li, J.; Hng, H. H.; Zhou, W.; Chen, X.; Xie, S. Highly Stretchable, Integrated Supercapacitors Based on Single-Walled Carbon Nanotube Films with Continuous Reticulate Architecture. Adv. Mater. 2013, 25, 1058−1064.
S13
7. Chen, T.; Peng, H.; Durstock, M.; Dai, L. High-Performance Transparent and Stretchable All-Solid Supercapacitors Based on Highly Aligned Carbon Nanotube Sheets. Sci. Rep. 2014, 4, 03612. 8. Yu, Z.; Niu, X.; Liu, Z.; Pei, Q. Intrinsically Stretchable Polymer Light-Emitting Devices Using Carbon Nanotube Polymer Composite Electrodes. Adv. Mater. 2011, 23, 3989–3994.
S14
