Molecular tailoring to improve polypyrrole hydrogels’ stiffness and electrochemical energy storage capacity

Abstract

This research looks at ways of tailoring and improving the stiffness of polypyrrole hydrogels for use as flexible supercapacitor electrodes. Molecules providing additional cross-linking between polypyrrole chains are added post-polymerisation but before gelation, and are found to increase gel stiffness by up to 600%, with the degree of change dependent on reactant type and proportion. It was also found that addition of phytic acid led to an increase in pseudocapacitive behaviour of the hydrogel, and thus a maximum specific capacitance of 217.07 F·g⁻¹ could be achieved. This is an increase of 140% compared to pristine polypyrrole hydrogels produced by this method.

Graphical abstract

Keywords

supercapacitor / polypyrrole / hydrogel / strengthening / electrochemical

References

[1] González A, Goikolea E, Barrena J A, Mysyk R. Review on supercapacitors: Technologies and material. Renewable & Sustainable Energy Reviews, 2016, 58: 1189–1206

[2] Shown I, Ganguly A, Chen L C, Chen K H. Conducting polymer-based flexible supercapacitor. Energy Science & Engineering, 2015, 3(1): 2–26

[3] Wang G, Zhang L, Zhang J. A review of electrode materials for electrochemical supercapacitors. Chemical Society Reviews, 2012, 41(2): 797–828

[4] Shi Y, Yu G. Designing hierarchically nanostructured conductive polymer gels for electrochemical energy storage and conversion. Chemistry of Materials, 2016, 28(8): 2466–2477

[5] Stejskal J, Trchovä M, Bober P, Moràvkovà Z, Kopecký D, Vrňata M, Prokeš J, Varga M, Watzlovà E. Polypyrrole salts and bases: Superior conductivity of nanotubes and their stability towards the loss of conductivity by deprotonation. RSC Advances, 2016, 6(91): 88382–88391

[6] Zhang X, Zhang J, Song W, Lu Z. Controllable synthesis of conducting polypyrrole nanostructures. Journal of Physical Chemistry B, 2006, 110(3): 1158–1165

[7] Kaynak A. Electrical conductivity of polypyrrole films at a temperature range of 70 K to 350 K. Materials Research Bulletin, 1998, 33(1): 81–88

[8] Brédas J L, Thémans B, André J M. Bipolarons in polypyrrole chains. Physical Review. B, 1983, 27(12): 7827–7830

[9] Otaigbe J U. The processing, structure and properties of elastomeric fibres. Handbook of Textile Fibre Structure. Volume 1: Fundamentals and Manufactured Polymer Fibres. Cambridge: Elsevier, Woodhead Publishing, 2009, 1–528

[10] Tan Y, Ghandi K. Kinetics and mechanism of pyrrole chemical polymerization. Synthetic Metals, 2013, 175: 183–191

[11] Kang H, Geckeler K. Enhanced electrical conductivity of polypyrrole prepared by chemical oxidative polymerization: Effect of the preparation technique and polymer additive. Polymer, 2000, 41(18): 6931–6934

[12] Pan L, Chortos A, Yu G, Wang Y, Isaacson S, Allen R, Shi Y, Dauskardt R, Bao Z. An ultra-sensitive resistive pressure sensor based on hollow-sphere microstructure induced elasticity in conducting polymer film. Nature Communications, 2014, 5(1): 1–8

[13] Shi Y, Pan L, Liu B, Wang Y, Cui Y, Bao Z, Yu G. Nanostructured conductive polypyrrole hydrogels as high-performance, flexible supercapacitor electrodes. Journal of Materials Chemistry. A, Materials for Energy and Sustainability, 2014, 2(17): 6086–6091

[14] Rajesh M, Raj J C, Kim B C, Cho B B, Ko M, Yu K H. Supercapacitive studies on electropolymerized natural organic phosphate doped polypyrrole thin films. Electrochimica Acta, 2016, 220: 373–383

[15] Zhou H, Ni T, Qing X, Yue X, Li G, Lu Y. One-step construction of graphene-polypyrrole hydrogels and their superior electrochemical performance. RSC Advances, 2013, 4(8): 4134–4139

[16] Bai H, Sheng K, Zhang P, Li C, Shi G. Graphene oxide/conducting polymer composite hydrogels. Journal of Materials Chemistry, 2011, 21(46): 18653–18658

[17] Lu Y, He W, Cao T, Guo H, Zhang Y, Li Q, Shao Z, Cui Y, Zhang X. Elastic, conductive, polymeric hydrogels and sponges. Scientific Reports, 2014, 4: 1–8

[18] Zhou X, Li T, Wang J, Chen F, Zhou D, Liu Q, Zhang L, Shena J, Zhou X. Shape morphing of anisotropy-encoded tough hydrogels enabled by asymmetrically-induced swelling and site-specific mechanical strengthening. Journal of Materials Chemistry. B, Materials for Biology and Medicine, 2018, 29(29): 4731–4737

[19] Zhou X, Li T, Wang J, Chen F, Zhou D, Liu Q, Li B, Cheng J, Zhou X, Zheng B. Mechanochemical regulated origami with tough hydrogels by ion transfer printing. ACS Applied Materials & Interfaces, 2018, 10(10): 9077–9084

[20] Li T, Wang J, Zhang L, Yang J, Yang M, Zhu D, Zhou X, Handschuh-Wang S, Liua Y, Zhou X. “Freezing”, morphing, and folding of stretchy tough hydrogels. Journal of Materials Chemistry. B, Materials for Biology and Medicine, 2017, 29(29): 5726–5732

[21] Dai T, Qing X, Zhou H, Shen C, Wang J, Lu Y. Mechanically strong conducting hydrogels with special double network structure. Synthetic Metals, 2010, 160(7-8): 791–796

[22] Bredas J L, Scott J C, Yakushi K, Street G B. Polarons and bipolarons in polypyrrole: Evolution of the band structure and optical spectrum upon doping. Physical Review. B, 1984, 30(2): 1023–1025

[23] Wang Y, Shi Y, Pan L, Ding Y, Zhao Y, Li Y, Shi Y, Yu G. Dopant-enabled supramolecular approach for controlled synthesis of nanostructured conductive polymer hydrogels. Nano Letters, 2015, 15(11): 7736–7741

[24] Ghosh S, Inganäs O. Conducting polymer hydrogels as 3D electrodes: Applications for supercapacitors. Advanced Materials, 1999, 11(14): 1214–1218

[25] Neoh K G, Young T T, Kang E T, Tan K L. Structural and mechanical degradation of polypyrrole films due to aqueous media and heat treatment and the subsequent redoping characteristics. Journal of Applied Polymer Science, 1997, 64(3): 519–526

[26] Xie Q, Kuwabata S, Yoneyama H. EQCM studies on polypyrrole in aqueous solutions. Journal of Electroanalytical Chemistry, 1997, 420(1-2): 219–225

[27] MacDiarmid A G, Mammone R J, Kaner R B, Porter S J, Pethig R, Heeger A J, Rosseinsky D R. The concept of ‘doping’ of conducting polymers: The role of reduction potentials. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 1985, 314(1528): 3–15

[28] Diaz A, Crowley J, Bargon J, Gardini G, Torrance J. Electrooxidation of aromatic oligomers and conducting polymers. Journal of Electroanalytical Chemistry and Interfacial Electrochemistry, 1981, 121: 355–361

Acknowledgements

This work was made possible by funding provided by the Engineering and Physical Sciences Research Council (EPSRC), funding number “EP/N509565/1”

Open Access

This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.

RIGHTS & PERMISSIONS

2019 The Author(s) 2019. This article is published with open access at link.springer.com and journal.hep.com.cn