Functionalization of Polypropylene with High Dielectric Properties: Applications in Electric Energy Storage

T. C. Mike Chung

Department of Materials Science and Engineering, The Pennsylvania State University, University Park, USA.

DOI: 10.4236/gsc.2012.22006                

Abstract

Biaxial-oriented polypropylene (BOPP) thin films are currently used as dielectrics in state-of-the-art capacitors that show many advantages, such as low energy loss and high breakdown strength, but a limited energy density (<2 J/cm3). This paper reviews some of our experimental results in functionalization of polypropylene with the objective to increase its electric energy density and maintain all desirable properties. A family of PP copolymers with various moieties, such as OH, O-Si(CH3)3, long chain branching, and cross-linking structure, have been systematically synthesized and studied to examine their dielectric properties (i.e. dielectric constant, dielectric loss, breakdown strength, polarization under various temperatures and electric fields). Evidently, a high molecular weight poly(propylene-co-hexen-6-ol) copolymer (PP-OH) containing 4.2 mol% of polar OH groups shows a dielectric constant (ε) of about 4.6 (more than 2 times of BOPP)—which is independent on a wide range of temperatures and frequencies—and high breakdown strength > 600 MV/m. The PP-OH dielectric demonstrates a linear reversible charge storage behavior with high releasing energy density > 7 J/cm3 (2 - 3 times of BOPP) after an applied electric field at E = 600 MV/m, without showing any significant increase of energy loss and remnant polarization at zero electric field. On the other hand, a cross-linked polypropylene (x-PP) exhibits an ε ~ 3, which is independent of a wide range of temperatures and frequencies, slim polarization loops, high breakdown strength (E = 650 MV/m), narrow breakdown distribution, and reliable energy storage capacity > 5 J/cm3 (double that of state-of-the-art BOPP capacitors), without showing any increase in energy loss.

Keywords

Capacitor; Dielectric; Energy Storage; Polypropylene; Functional Polyolefin

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	M. Winter and R. J. Brodd, “What Are Batteries, Fuel Cells, and Supercapacitors?” Chemical Reviews, Vol. 104, No. 10, 2004, pp. 4245-4270. doi:10.1021/cr020730k
[2]	W. J. Sarjeant, “Advanced Power Sources for Space Missions, NAS-NRC (EEB) Committee on Advanced Spaced Based High Power Technologies,” National Academy Press, Washington DC, 1989.
[3]	W. J. Sarjeant, J. Zirnheld and F. W. MacDougall, “Capacitors,” IEEE Transactions on Plasma Science, Vol. 26, No. 5, 1998, pp. 1368-1392. doi:10.1109/27.736020
[4]	M. Villegas, J. F. Fernandez, C. Moure and P. Duran, “Preparation, Microstructural Development and Dielectric Properties of Pb(Mg1/3Nb2/3)O3-Pb(TixZr1?x)O3 Multilayer Ceramic Capacitors,” Journal of Materials Science, Vol. 29, No. 19, 1994, pp. 4999-5004. doi:10.1007/BF01151090
[5]	G. R. Love, “Energy Storage in Ceramic Dielectrics,” Journal of the American Ceramic Society, Vol. 73, No. 2, 1990, pp. 323-328.
[6]	C. W. Reed and S. W. Cichanowski, “The Fundamentals of Aging in HV Polymer-Film Capacitors,” IEEE Transactions on Dielectrics and Electrical Insulation, Vol. 1, No. 5, 1994, pp. 904-922. doi:10.1109/94.326658
[7]	W. J. Sarjeant, F. W. MacDougall and D. W. Larson, “Energy Storage in Polymer Laminate Structures-Ageing and Diagnostic Approaches for Life Validation,” IEEE Electrical Insulation Magazine, Vol. 13, No. 1, 1997, pp. 20-24. doi:10.1109/57.567394
[8]	J. H. Tortai, N. Bonifaci, A. Denat and C. Trassy, “Diagnostic of the Self-Healing of Metallized Polypropylene Film by Modeling of the Broadening Emission Lines of Aluminum Emitted by Plasma Discharge” Journal of Applied Physics, Vol. 97, No. 5, 2005, Article ID: 53304. doi:10.1063/1.1858872
[9]	M. Rabuffi and G. Picci, “Status Quo and Future Prospects for Metallized Polypropylene Energy Storage Capacitors,” IEEE Transactions on Plasma Science, Vol. 30, No. 5, 2002, pp. 1939-1942.
[10]	G. Picci and M. Rabuffi, “Pulse Handling Capability of Energy Storage Metallized Film Capacitors,” IEEE Transactions on Plasma Science, Vol. 28, No. 5, 2000, pp. 1603-1606. doi:10.1109/27.901241
[11]	J. A. Langston, J. Y. Dong and T. C. Chung, “One-Pot Process of Preparing Long Chain Branched Polypropylene (LCBPP) Using C2-Symmetric Metallocene Complex and A ‘T’ Reagent,” Macromolecules, Vol. 38, No. 14, 2005, pp. 5849-5853. doi:10.1021/ma0506841
[12]	J. A. Langston, R. H. Colby, T. Shimizu, T. Suzuki, M. Aoki and T. C. Chung, “Synthesis and Characterization of Long Chain Branched Isotactic Polypropy-lene (LCBPP) via Metallocene Catalyst and T-Reagent,” Macromolecules, Vol. 40, No. 8, 2007, pp. 2712-2720. doi:10.1021/ma062111+
[13]	T. C. Chung and A. Petchsuk, “Ferroelectric Polymers with Giant Electrostriction; Based on Semicrystalline Ter-polymers Containing Vinylidene Difluroride, Trifluroethylene and Third Monomer,” US Patent No. 6,355,749, 2002.
[14]	Z. C. Zhang and T. C. Chung, “Fluoro-Terpolymer Based Capacitors Having High Energy Density, Low Energy Loss, and High Pulsed Charge-Discharge Cycles,” Macromolecules, Vol. 40, No. 4, 2007, pp. 783-785. doi:10.1021/ma0627119
[15]	Z. C. Zhang and T. C. Chung, “The Structure-Property Relationship of PVDF-Based Polymers with Energy Storage and Loss under Applied Electric Fields,” Macromolecules, Vol. 40, No. 26, 2007, pp. 9391-9397. doi:10.1021/ma071561e
[16]	T. C. Chung and A. Petchsuk, “Synthesis and Properties of Ferroelectric Fluoro-Terpolymers with Curie Transition at Ambient Temperature,” Macromolecules, Vol. 35, No. 20, 2002, pp. 7678-7684. doi:10.1021/ma020504c
[17]	Z. Wang, Z. C. Zhang and T. C. Chung, “High Dielectric VDF/TrFE/CTFE Terpolymers Pre-pared by Hydrogenation of VDF/CTFE Copolymers; Synthesis and Characterization,” Macromolecules, Vol. 39, No. 13, 2006, pp. 4268-4271. doi:10.1021/ma060738m
[18]	T. C. Chung, “Functionalization of Polyolefins,” Academic Press, London, 2002.
[19]	T. C. Chung, “Synthesis of Functional Polyolefin Copolymers with Graft and Block Structures,” Progress in Polymer Science, Vol. 27, No. 1, 2002, pp. 39-85. doi:10.1016/S0079-6700(01)00038-7
[20]	X. Yuan, Y. Mat-suyama and T. C. Chung, “Synthesis of Functionalized Isotactic Polypropylene Dielectrics for Electric Storage Application,” Macromolecules, Vol. 43, No. 9, 2010, pp. 4011-4015. doi:10.1021/ma100209d
[21]	W. Lin, Z. Shao, J. Y. Dong and T. C. Chung, “Cross- Linked Polypropylene Prepared by PP Copolymers Containing Flexible Styrene Groups,” Macromo-lecules, Vol. 42, No. 11, 2009, pp. 3750-3754. doi:10.1021/ma9002775
[22]	X. Yuan and T. C. Chung, “Cross-Linking Effect on Dielectric Properties of Polypropy-lene Thin Films and Applications in Electric Energy Storage,” Applied Physics Letters, Vol. 98, No. 6, 2011, Article ID 62901. doi:10.1063/1.3552710
[23]	J. Artbauer, “Electric Strength of Polymers,” Journal of Physics D: Applied Physics, Vol. 29, No. 2, 1996, p. 446. doi:10.1088/0022-3727/29/2/024
[24]	C. C. Xu, J. Ho and S. A. Boggs, “Automatic Breakdown Voltage Measurement of Polymer Films,” IEEE Electrical Insulation Magazine, Vol. 24, No. 6, 2008, pp. 30-34. doi:10.1109/MEI.2008.4665348