High-Performance Flexible Asymmetric Supercapacitor Based on CoAl-LDH and rGO Electrodes
Corresponding Author: Dingsheng Yuan
Nano-Micro Letters,
Vol. 9 No. 3 (2017), Article Number: 31
Abstract
A flexible asymmetric supercapacitor (ASC) based on a CoAl-layered double hydroxide (CoAl-LDH) electrode and a reduced graphene oxide (rGO) electrode was successfully fabricated. The CoAl-LDH electrode as a positive electrode was synthesized by directly growing CoAl-LDH nanosheet arrays on a carbon cloth (CC) through a facile hydrothermal method, and it delivered a specific capacitance of 616.9 F g−1 at a current density of 1 A g−1. The rGO electrode as a negative electrode was synthesized by coating rGO on the CC via a simple dip-coating method and revealed a specific capacitance of 110.0 F g−1 at a current density of 2 A g−1. Ultimately, the advanced ASC offered a broad voltage window (1.7 V) and exhibited a high superficial capacitance of 1.77 F cm−2 at 2 mA cm−2 and a high energy density of 0.71 mWh cm−2 at a power density of 17.05 mW cm−2, along with an excellent cycle stability (92.9% capacitance retention over 8000 charge–discharge cycles).
Highlights:
1 CoAl-LDH (layer double hydroxide) electrode and binder-free rGO (reduced graphene oxide) electrode were successfully synthesized and assembled to produce a flexible ASC (asymmetric supercapacitor).
2 The assembled ASC device exhibited excellent capacitive performance.
Keywords
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- T. Li, G.H. Li, L.H. Li, L. Liu, Y. Xu, H.Y. Ding, T. Zhang, Large-scale self-assembly of 3D flower-like hierarchical Ni/Co-LDHs microspheres for high-performance flexible asymmetric supercapacitors. ACS Appl. Mater. Interfaces 8, 2562–2572 (2016). doi:10.1021/acsami.5b10158
- M. Shao, Z. Li, R. Zhang, F. Ning, M. Wei, D.G. Evans, X. Duan, Hierarchical conducting polymer@clay core-shell arrays for flexible all-solid-state supercapacitor devices. Small 11, 3530–3538 (2015). doi:10.1002/smll.201403421
- Y. Li, J. Dong, J. Zhang, X. Zhao, P. Yu, L. Jin, Q. Zhang, Nitrogen-doped carbon membrane derived from polyimide as free-standing electrodes for flexible supercapacitors. Small 11, 3476–3484 (2015). doi:10.1002/smll.201403575
- Z. Qi, A. Younis, D. Chu, S. Li, A facile and template-free one-pot synthesis of Mn3O4 nanostructures as electrochemical supercapacitors. Nano-Micro Lett. 8, 165–173 (2015). doi:10.1007/s40820-015-0074-0
- Z.H. Wang, D.O. Carlsson, P. Tammela, K. Hua, P. Zhang, L. Nyholm, M. Stromme, Surface modified nanocellulose fibers yield conducting polymer-based flexible supercapacitors with enhanced capacitances. ACS Nano 9, 7563–7571 (2015). doi:10.1021/acsnano.5b02846
- Z. Li, M. Shao, L. Zhou, R. Zhang, C. Zhang, J. Han, M. Wei, D.G. Evans, X. Duan, A flexible all-solid-state micro-supercapacitor based on hierarchical CuO@layered double hydroxide core–shell nanoarrays. Nano Energy 20, 294–304 (2016). doi:10.1016/j.nanoen.2015.12.030
- H. Chen, S. Zeng, M. Chen, Y. Zhang, Q. Li, Fabrication and functionalization of carbon nanotube films for high-performance flexible supercapacitors. Carbon 92, 271–296 (2015). doi:10.1016/j.carbon.2015.04.010
- G.S. Gund, D.P. Dubal, N.R. Chodankar, J.Y. Cho, P. Gomez-Romero, C. Park, C.D. Lokhande, Low-cost flexible supercapacitors with high-energy density based on nanostructured MnO2 and Fe2O3 thin films directly fabricated onto stainless steel. Sci. Rep. 5, 12454 (2015). doi:10.1038/srep12454
- X. Zang, X. Li, M. Zhu, X. Li, Z. Zhen, Y. He, K. Wang, J. Wei, F. Kang, H. Zhu, Graphene/polyaniline woven fabric composite films as flexible supercapacitor electrodes. Nanoscale 7, 7318–7322 (2015). doi:10.1039/c5nr00584a
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- X. Dong, L. Wang, D. Wang, C. Li, J. Jin, Layer-by-layer engineered Co-Al hydroxide nanosheets/graphene multilayer films as flexible electrode for supercapacitor. Langmuir 28, 293–298 (2012). doi:10.1021/la2038685
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- L.F. Chen, Z.Y. Yu, X. Ma, Z.Y. Li, S.H. Yu, In situ hydrothermal growth of ferric oxides on carbon cloth for low-cost and scalable high-energy-density supercapacitors. Nano Energy 9, 345–354 (2014). doi:10.1016/j.nanoen.2014.07.021
- L. Wang, D. Wang, X.Y. Dong, Z.J. Zhang, X.F. Pei, X.J. Chen, B. Chen, J. Jin, Layered assembly of graphene oxide and Co-Al layered double hydroxide nanosheets as electrode materials for supercapacitors. Chem. Commun. 47, 3556–3558 (2011). doi:10.1039/c0cc05420h
- X. Cao, B. Zheng, W. Shi, J. Yang, Z. Fan, Z. Luo, X. Rui, B. Chen, Q. Yan, H. Zhang, Reduced graphene oxide-wrapped MoO3 composites prepared by using metal-organic frameworks as precursor for all-solid-state flexible supercapacitors. Adv. Mater. 27, 4695–4701 (2015). doi:10.1002/adma.201501310
- J. Xu, Q.F. Wang, X.W. Wang, Q.Y. Xiang, B. Hang, D. Chen, G.Z. Shen, Flexible asymmetric supercapacitors based upon Co9S8 nanorod//Co3O4@RuO2 nanosheet arrays on carbon cloth. ACS Nano 7, 5453–5462 (2013). doi:10.1021/nn401450s
- W. Lin, W. Yu, Z. Hu, W. Ouyang, X. Shao, R. Li, D.S. Yuan, Superior performance asymmetric supercapacitors based on flake-like Co/Al hydrotalcite and graphene. Electrochim. Acta 143, 331–339 (2014). doi:10.1016/j.electacta.2014.08.024
- P. Sun, Z. Deng, P. Yang, X. Yu, Y. Chen, Z. Liang, H. Meng, W. Xie, S. Tan, W. Mai, Freestanding CNT–WO3 hybrid electrodes for flexible asymmetric supercapacitors. J. Mater. Chem. A 3, 12076–12080 (2015). doi:10.1039/c5ta02316e
- M. Boota, B. Anasori, C. Voigt, M.Q. Zhao, M.W. Barsoum, Y. Gogotsi, Pseudocapacitive electrodes produced by oxidant-free polymerization of pyrrole between the layers of 2D titanium carbide (MXene). Adv. Mater. 28, 1517–1522 (2016). doi:10.1002/adma.201504705
- G. Sun, X. Zhang, R. Lin, J. Yang, H. Zhang, P. Chen, Hybrid fibers made of molybdenum disulfide, reduced graphene oxide, and multi-walled carbon nanotubes for solid-state, flexible, asymmetric supercapacitors. Angew. Chem. Int. Ed. 54, 4651–4656 (2015). doi:10.1002/anie.201411533
- X. Wu, L. Jiang, C. Long, T. Wei, Z. Fan, Dual support system ensuring porous co-al hydroxide nanosheets with ultrahigh rate performance and high energy density for supercapacitors. Adv. Funct. Mater. 25, 1648–1655 (2015). doi:10.1002/adfm.201404142
- W. Yu, W. Lin, X. Shao, Z. Hu, R. Li, D. Yuan, High performance supercapacitor based on Ni3S2/carbon nanofibers and carbon nanofibers electrodes derived from bacterial cellulose. J. Power Sources 272, 137–143 (2014). doi:10.1016/j.jpowsour.2014.08.064
- J. Chen, X. Wang, J. Wang, P.S. Lee, Sulfidation of NiMn-layered double hydroxides/graphene oxide composites toward supercapacitor electrodes with enhanced performance. Adv. Energy Mater. 6, 1501745 (2016). doi:10.1002/aenm.201501745
- J. Tao, W. Ma, N. Liu, X. Ren, Y. Shi, J. Su, Y. Gao, High-performance solid-state supercapacitors fabricated by pencil drawing and polypyrrole depositing on paper substrate. Nano-Micro Lett. 7, 276–281 (2015). doi:10.1007/s40820-015-0039-3
- M. Li, F. Liu, J.P. Cheng, J. Ying, X.B. Zhang, Enhanced performance of nickel–aluminum layered double hydroxide nanosheets/carbon nanotubes composite for supercapacitor and asymmetric capacitor. J. Alloys Compd. 635, 225–232 (2015). doi:10.1016/j.jallcom.2015.02.130
- L. Li, Q. Zhong, N.D. Kim, G. Ruan, Y. Yang et al., Nitrogen-doped carbonized cotton for highly flexible supercapacitors. Carbon 105, 260–267 (2016). doi:10.1016/j.carbon.2016.04.031
- M.A. Bissett, I.A. Kinloch, R.A. Dryfe, Characterization of MoS2-graphene composites for high-performance coin cell supercapacitors. ACS Appl. Mater. Interfaces 7, 17388–17398 (2015). doi:10.1021/acsami.5b04672
- Y.P. Chen, B.R. Liu, Q. Liu, J. Wang, Z.S. Li, X.Y. Jing, L.H. Liu, Coaxial CoMoO4 nanowire arrays with chemically integrated conductive coating for high-performance flexible all-solid-state asymmetric supercapacitors. Nanoscale 7, 15159–15167 (2015). doi:10.1039/C5NR02961A
- L. Jiang, L. Sheng, C. Long, T. Wei, Z. Fan, Functional pillared graphene frameworks for ultrahigh volumetric performance supercapacitors. Adv. Energy Mater. 5, 1500771 (2015). doi:10.1002/aenm.201500771
- M. Li, J.P. Cheng, F. Liu, X.B. Zhang, 3D-architectured nickel–cobalt–manganese layered double hydroxide/reduced graphene oxide composite for high-performance supercapacitor. Chem. Phys. Lett. 640, 5–10 (2015). doi:10.1016/j.cplett.2015.10.003
- A.D. Jagadale, G. Guan, X. Li, X. Du, X. Ma, X. Hao, A. Abudula, Ultrathin nanoflakes of cobalt–manganese layered double hydroxide with high reversibility for asymmetric supercapacitor. J. Power Sources 306, 526–534 (2016). doi:10.1016/j.jpowsour.2015.12.097
- Z. Huang, S. Wang, J. Wang, Y. Yu, J. Wen, R. Li, Exfoliation-restacking synthesis of coal-layered double hydroxide nanosheets/reduced graphene oxide composite for high performance supercapacitors. Electrochim. Acta 152, 117–125 (2015). doi:10.1016/j.electacta.2014.11.085
- Z.Y. Yu, L.F. Chen, S.H. Yu, Growth of NiFe2O4 nanoparticles on carbon cloth for high performance flexible supercapacitors. J. Mater. Chem. A 2, 10889 (2014). doi:10.1039/c4ta00492b
- J. Wen, S. Li, K. Zhou, Z. Song, B. Li, Z. Chen, T. Chen, Y. Guo, G. Fang, Flexible coaxial-type fiber solid-state asymmetrical supercapacitor based on Ni3S2 nanorod array and pen ink electrodes. J. Power Sources 324, 325–333 (2016). doi:10.1016/j.jpowsour.2016.05.087
- X. Yang, K. Xu, R. Zou, J. Hu, A hybrid electrode of Co3O4@PPy core/shell nanosheet arrays for high-performance supercapacitors. Nano-Micro Lett. 8, 143–150 (2015). doi:10.1007/s40820-015-0069-x
- S. Huang, G.N. Zhu, C. Zhang, W.W. Tjiu, Y.Y. Xia, T. Liu, Immobilization of Co-Al layered double hydroxides on graphene oxide nanosheets: growth mechanism and supercapacitor studies. ACS Appl. Mater. Interfaces 4, 2242–2249 (2012). doi:10.1021/am300247x
- J.X. Feng, S.H. Ye, X.F. Lu, Y.X. Tong, G.R. Li, Asymmetric paper supercapacitor based on amorphous porous Mn3O4 negative electrode and Ni(OH)2 positive electrode: a novel and high-performance flexible electrochemical energy storage device. ACS Appl. Mater. Interfaces 7, 11444–11451 (2015). doi:10.1021/acsami.5b02157
- B. Liu, D. Kong, Z.X. Huang, R. Mo, Y. Wang, Z. Han, C. Cheng, H.Y. Yang, Three-dimensional hierarchical NiCo2O4 nanowire@Ni3S2 nanosheet core/shell arrays for flexible asymmetric supercapacitors. Nanoscale 8, 10686–10694 (2016). doi:10.1039/C6NR02600A
- Z. Su, C. Yang, C. Xu, H. Wu, Z. Zhang, T. Liu, C. Zhang, Q. Yang, B. Li, F. Kang, Co-electro-deposition of the MnO2–PEDOT:PSS nanostructured composite for high areal mass, flexible asymmetric supercapacitor devices. J. Mater. Chem. A 1, 12432 (2013). doi:10.1039/C3TA13148C
- A. Sumboja, C.Y. Foo, X. Wang, P.S. Lee, Large areal mass, flexible and free-standing reduced graphene oxide/manganese dioxide paper for asymmetric supercapacitor device. Adv. Mater. 25, 2809–2815 (2013). doi:10.1002/adma.201205064
- J. Tao, N. Liu, L. Li, J. Su, Y. Gao, Hierarchical nanostructures of polypyrrole@MnO2 composite electrodes for high performance solid-state asymmetric supercapacitors. Nanoscale 6, 2922–2928 (2014). doi:10.1039/C3NR05845J
- W. Zilong, Z. Zhu, J. Qiu, S. Yang, High performance flexible solid-state asymmetric supercapacitors from MnO2/ZnO core–shell nanorods//specially reduced graphene oxide. J. Mater. Chem. C 2, 1331–1336 (2014). doi:10.1039/C3TC31476F
References
T. Li, G.H. Li, L.H. Li, L. Liu, Y. Xu, H.Y. Ding, T. Zhang, Large-scale self-assembly of 3D flower-like hierarchical Ni/Co-LDHs microspheres for high-performance flexible asymmetric supercapacitors. ACS Appl. Mater. Interfaces 8, 2562–2572 (2016). doi:10.1021/acsami.5b10158
M. Shao, Z. Li, R. Zhang, F. Ning, M. Wei, D.G. Evans, X. Duan, Hierarchical conducting polymer@clay core-shell arrays for flexible all-solid-state supercapacitor devices. Small 11, 3530–3538 (2015). doi:10.1002/smll.201403421
Y. Li, J. Dong, J. Zhang, X. Zhao, P. Yu, L. Jin, Q. Zhang, Nitrogen-doped carbon membrane derived from polyimide as free-standing electrodes for flexible supercapacitors. Small 11, 3476–3484 (2015). doi:10.1002/smll.201403575
Z. Qi, A. Younis, D. Chu, S. Li, A facile and template-free one-pot synthesis of Mn3O4 nanostructures as electrochemical supercapacitors. Nano-Micro Lett. 8, 165–173 (2015). doi:10.1007/s40820-015-0074-0
Z.H. Wang, D.O. Carlsson, P. Tammela, K. Hua, P. Zhang, L. Nyholm, M. Stromme, Surface modified nanocellulose fibers yield conducting polymer-based flexible supercapacitors with enhanced capacitances. ACS Nano 9, 7563–7571 (2015). doi:10.1021/acsnano.5b02846
Z. Li, M. Shao, L. Zhou, R. Zhang, C. Zhang, J. Han, M. Wei, D.G. Evans, X. Duan, A flexible all-solid-state micro-supercapacitor based on hierarchical CuO@layered double hydroxide core–shell nanoarrays. Nano Energy 20, 294–304 (2016). doi:10.1016/j.nanoen.2015.12.030
H. Chen, S. Zeng, M. Chen, Y. Zhang, Q. Li, Fabrication and functionalization of carbon nanotube films for high-performance flexible supercapacitors. Carbon 92, 271–296 (2015). doi:10.1016/j.carbon.2015.04.010
G.S. Gund, D.P. Dubal, N.R. Chodankar, J.Y. Cho, P. Gomez-Romero, C. Park, C.D. Lokhande, Low-cost flexible supercapacitors with high-energy density based on nanostructured MnO2 and Fe2O3 thin films directly fabricated onto stainless steel. Sci. Rep. 5, 12454 (2015). doi:10.1038/srep12454
X. Zang, X. Li, M. Zhu, X. Li, Z. Zhen, Y. He, K. Wang, J. Wei, F. Kang, H. Zhu, Graphene/polyaniline woven fabric composite films as flexible supercapacitor electrodes. Nanoscale 7, 7318–7322 (2015). doi:10.1039/c5nr00584a
T.M. Masikhwa, M.J. Madito, D.Y. Momodu, J.K. Dangbegnon, O. Guellati et al., High performance asymmetric supercapacitor based on CoAl-LDH/GF and activated carbon from expanded graphite. RSC Adv. 6, 46723–46732 (2016). doi:10.1039/c6ra07419g
X. Dong, L. Wang, D. Wang, C. Li, J. Jin, Layer-by-layer engineered Co-Al hydroxide nanosheets/graphene multilayer films as flexible electrode for supercapacitor. Langmuir 28, 293–298 (2012). doi:10.1021/la2038685
J. Zhao, J. Chen, S. Xu, M. Shao, Q. Zhang, F. Wei, J. Ma, M. Wei, D.G. Evans, X. Duan, Hierarchical NiMn layered double hydroxide/carbon nanotubes architecture with superb energy density for flexible supercapacitors. Adv. Funct. Mater. 24, 2938–2946 (2014). doi:10.1002/adfm.201303638
L.F. Chen, Z.Y. Yu, X. Ma, Z.Y. Li, S.H. Yu, In situ hydrothermal growth of ferric oxides on carbon cloth for low-cost and scalable high-energy-density supercapacitors. Nano Energy 9, 345–354 (2014). doi:10.1016/j.nanoen.2014.07.021
L. Wang, D. Wang, X.Y. Dong, Z.J. Zhang, X.F. Pei, X.J. Chen, B. Chen, J. Jin, Layered assembly of graphene oxide and Co-Al layered double hydroxide nanosheets as electrode materials for supercapacitors. Chem. Commun. 47, 3556–3558 (2011). doi:10.1039/c0cc05420h
X. Cao, B. Zheng, W. Shi, J. Yang, Z. Fan, Z. Luo, X. Rui, B. Chen, Q. Yan, H. Zhang, Reduced graphene oxide-wrapped MoO3 composites prepared by using metal-organic frameworks as precursor for all-solid-state flexible supercapacitors. Adv. Mater. 27, 4695–4701 (2015). doi:10.1002/adma.201501310
J. Xu, Q.F. Wang, X.W. Wang, Q.Y. Xiang, B. Hang, D. Chen, G.Z. Shen, Flexible asymmetric supercapacitors based upon Co9S8 nanorod//Co3O4@RuO2 nanosheet arrays on carbon cloth. ACS Nano 7, 5453–5462 (2013). doi:10.1021/nn401450s
W. Lin, W. Yu, Z. Hu, W. Ouyang, X. Shao, R. Li, D.S. Yuan, Superior performance asymmetric supercapacitors based on flake-like Co/Al hydrotalcite and graphene. Electrochim. Acta 143, 331–339 (2014). doi:10.1016/j.electacta.2014.08.024
P. Sun, Z. Deng, P. Yang, X. Yu, Y. Chen, Z. Liang, H. Meng, W. Xie, S. Tan, W. Mai, Freestanding CNT–WO3 hybrid electrodes for flexible asymmetric supercapacitors. J. Mater. Chem. A 3, 12076–12080 (2015). doi:10.1039/c5ta02316e
M. Boota, B. Anasori, C. Voigt, M.Q. Zhao, M.W. Barsoum, Y. Gogotsi, Pseudocapacitive electrodes produced by oxidant-free polymerization of pyrrole between the layers of 2D titanium carbide (MXene). Adv. Mater. 28, 1517–1522 (2016). doi:10.1002/adma.201504705
G. Sun, X. Zhang, R. Lin, J. Yang, H. Zhang, P. Chen, Hybrid fibers made of molybdenum disulfide, reduced graphene oxide, and multi-walled carbon nanotubes for solid-state, flexible, asymmetric supercapacitors. Angew. Chem. Int. Ed. 54, 4651–4656 (2015). doi:10.1002/anie.201411533
X. Wu, L. Jiang, C. Long, T. Wei, Z. Fan, Dual support system ensuring porous co-al hydroxide nanosheets with ultrahigh rate performance and high energy density for supercapacitors. Adv. Funct. Mater. 25, 1648–1655 (2015). doi:10.1002/adfm.201404142
W. Yu, W. Lin, X. Shao, Z. Hu, R. Li, D. Yuan, High performance supercapacitor based on Ni3S2/carbon nanofibers and carbon nanofibers electrodes derived from bacterial cellulose. J. Power Sources 272, 137–143 (2014). doi:10.1016/j.jpowsour.2014.08.064
J. Chen, X. Wang, J. Wang, P.S. Lee, Sulfidation of NiMn-layered double hydroxides/graphene oxide composites toward supercapacitor electrodes with enhanced performance. Adv. Energy Mater. 6, 1501745 (2016). doi:10.1002/aenm.201501745
J. Tao, W. Ma, N. Liu, X. Ren, Y. Shi, J. Su, Y. Gao, High-performance solid-state supercapacitors fabricated by pencil drawing and polypyrrole depositing on paper substrate. Nano-Micro Lett. 7, 276–281 (2015). doi:10.1007/s40820-015-0039-3
M. Li, F. Liu, J.P. Cheng, J. Ying, X.B. Zhang, Enhanced performance of nickel–aluminum layered double hydroxide nanosheets/carbon nanotubes composite for supercapacitor and asymmetric capacitor. J. Alloys Compd. 635, 225–232 (2015). doi:10.1016/j.jallcom.2015.02.130
L. Li, Q. Zhong, N.D. Kim, G. Ruan, Y. Yang et al., Nitrogen-doped carbonized cotton for highly flexible supercapacitors. Carbon 105, 260–267 (2016). doi:10.1016/j.carbon.2016.04.031
M.A. Bissett, I.A. Kinloch, R.A. Dryfe, Characterization of MoS2-graphene composites for high-performance coin cell supercapacitors. ACS Appl. Mater. Interfaces 7, 17388–17398 (2015). doi:10.1021/acsami.5b04672
Y.P. Chen, B.R. Liu, Q. Liu, J. Wang, Z.S. Li, X.Y. Jing, L.H. Liu, Coaxial CoMoO4 nanowire arrays with chemically integrated conductive coating for high-performance flexible all-solid-state asymmetric supercapacitors. Nanoscale 7, 15159–15167 (2015). doi:10.1039/C5NR02961A
L. Jiang, L. Sheng, C. Long, T. Wei, Z. Fan, Functional pillared graphene frameworks for ultrahigh volumetric performance supercapacitors. Adv. Energy Mater. 5, 1500771 (2015). doi:10.1002/aenm.201500771
M. Li, J.P. Cheng, F. Liu, X.B. Zhang, 3D-architectured nickel–cobalt–manganese layered double hydroxide/reduced graphene oxide composite for high-performance supercapacitor. Chem. Phys. Lett. 640, 5–10 (2015). doi:10.1016/j.cplett.2015.10.003
A.D. Jagadale, G. Guan, X. Li, X. Du, X. Ma, X. Hao, A. Abudula, Ultrathin nanoflakes of cobalt–manganese layered double hydroxide with high reversibility for asymmetric supercapacitor. J. Power Sources 306, 526–534 (2016). doi:10.1016/j.jpowsour.2015.12.097
Z. Huang, S. Wang, J. Wang, Y. Yu, J. Wen, R. Li, Exfoliation-restacking synthesis of coal-layered double hydroxide nanosheets/reduced graphene oxide composite for high performance supercapacitors. Electrochim. Acta 152, 117–125 (2015). doi:10.1016/j.electacta.2014.11.085
Z.Y. Yu, L.F. Chen, S.H. Yu, Growth of NiFe2O4 nanoparticles on carbon cloth for high performance flexible supercapacitors. J. Mater. Chem. A 2, 10889 (2014). doi:10.1039/c4ta00492b
J. Wen, S. Li, K. Zhou, Z. Song, B. Li, Z. Chen, T. Chen, Y. Guo, G. Fang, Flexible coaxial-type fiber solid-state asymmetrical supercapacitor based on Ni3S2 nanorod array and pen ink electrodes. J. Power Sources 324, 325–333 (2016). doi:10.1016/j.jpowsour.2016.05.087
X. Yang, K. Xu, R. Zou, J. Hu, A hybrid electrode of Co3O4@PPy core/shell nanosheet arrays for high-performance supercapacitors. Nano-Micro Lett. 8, 143–150 (2015). doi:10.1007/s40820-015-0069-x
S. Huang, G.N. Zhu, C. Zhang, W.W. Tjiu, Y.Y. Xia, T. Liu, Immobilization of Co-Al layered double hydroxides on graphene oxide nanosheets: growth mechanism and supercapacitor studies. ACS Appl. Mater. Interfaces 4, 2242–2249 (2012). doi:10.1021/am300247x
J.X. Feng, S.H. Ye, X.F. Lu, Y.X. Tong, G.R. Li, Asymmetric paper supercapacitor based on amorphous porous Mn3O4 negative electrode and Ni(OH)2 positive electrode: a novel and high-performance flexible electrochemical energy storage device. ACS Appl. Mater. Interfaces 7, 11444–11451 (2015). doi:10.1021/acsami.5b02157
B. Liu, D. Kong, Z.X. Huang, R. Mo, Y. Wang, Z. Han, C. Cheng, H.Y. Yang, Three-dimensional hierarchical NiCo2O4 nanowire@Ni3S2 nanosheet core/shell arrays for flexible asymmetric supercapacitors. Nanoscale 8, 10686–10694 (2016). doi:10.1039/C6NR02600A
Z. Su, C. Yang, C. Xu, H. Wu, Z. Zhang, T. Liu, C. Zhang, Q. Yang, B. Li, F. Kang, Co-electro-deposition of the MnO2–PEDOT:PSS nanostructured composite for high areal mass, flexible asymmetric supercapacitor devices. J. Mater. Chem. A 1, 12432 (2013). doi:10.1039/C3TA13148C
A. Sumboja, C.Y. Foo, X. Wang, P.S. Lee, Large areal mass, flexible and free-standing reduced graphene oxide/manganese dioxide paper for asymmetric supercapacitor device. Adv. Mater. 25, 2809–2815 (2013). doi:10.1002/adma.201205064
J. Tao, N. Liu, L. Li, J. Su, Y. Gao, Hierarchical nanostructures of polypyrrole@MnO2 composite electrodes for high performance solid-state asymmetric supercapacitors. Nanoscale 6, 2922–2928 (2014). doi:10.1039/C3NR05845J
W. Zilong, Z. Zhu, J. Qiu, S. Yang, High performance flexible solid-state asymmetric supercapacitors from MnO2/ZnO core–shell nanorods//specially reduced graphene oxide. J. Mater. Chem. C 2, 1331–1336 (2014). doi:10.1039/C3TC31476F