Polymer electrolytes have attracted considerable attention due mainly to the possibility of their application in various electrochemical devices such as rechargeable lithium batteries. According to the above-mentioned introduction to polymer electrolytes, there remains intense interest in developing solid polymer electrolytes, free from low molecular weight plasticizer and with a sufficiently high ionic conductivity for application in all-solid-state rechargeable lithium batteries. For such applications, conductivities above the present maximum of 10-4 S cm-1 are required.
Gel-type electrolytes, in which a liquid electrolyte is entrapped in a polymer matrix,
possess levels of ionic conductivity that are sufficient for application in lithium batteries. These materials will lead to the first commercialization of polymer batteries.
Nevertheless, such electrolytes did not get rid of the problems, which are many of disadvantages associated with liquid electrolytes still retained in the gel.
Great progress has been made over the last 30 years in increasing the level of ionic conductivity exhibited by polymer electrolytes. However, despite innovative designs of flexible polymers and the addition of inorganic materials to form polymer composite capable of suppressing crystallinity, levels of ionic conductivity are persistently limited to a ceiling of around 10-4 S cm-1 at room temperature. Such a level is insufficient for many lithium battery applications.
When such barriers are reached in science, it is time to change the way we think.
Our version is that we must direct our attention to the phase behavior and interaction mechanism of polymer electrolytes. It is of vital importance to optimize the performance of the ionic conductivity through understanding of the fundamentals of ionic interaction mechanism and phase behavior in full detail within polymer electrolytes.
Poly(ethylene oxide) (PEO)-based polymer electrolytes are still among the most extensively studied polymer ionic conductor owing to their structures are beneficial for facilitating fast ion transport. Unfortunately, a high content of a crystalline phase limits the conductivity of PEO-based electrolytes. It is an important challenge to develop practical methods for preparing the SPEs for that have higher conductivity and dimensional stability. In this regard, the preparation of polymer electrolytes by blending them with other appropriate polymers is of interest. Polymer blend is a quick and economical alternative method for obtaining materials that have optimized properties and for the easy control of their physical properties by compositional change. Therefore, the introduce of poly(ε-caprolactone) (PCL) into PEO-based
polymer electrolytes tends to suppress the crystallization of PEO and results in higher ionic conductivity. In Chapter 3, we employed differential scanning calorimetry (DSC), Fourier transform infrared (FTIR), solid-state 7Li NMR, and alternating current (ac) impedance to investigate the miscibility and related conductivity behaviors of this LiClO4/PEO/PCL ternary blend system. Subsequently, we synthesize monomethoxypoly(ethylene glycol)-block-poly(ε-caprolactone) (MPEG-PCL) block copolymers and blend them with LiClO4 salt to study the influences that the miscibility behavior and interaction mechanisms have on the variation of ionic conductivity, which was discussed in Chapter 4.
Finally, since poly(vinyl pyrrolidone) (PVP) and poly(methyl methacrylate) (PMMA) both possess their own advantages to act as polymer electrolyte, we are interested in studying the polymer electrolyte incorporating lithium perchlorate with PVP and PMMA. However, PVP/PMMA blends tend to be immiscible, therefore, PVP-co-PMMA random copolymer was synthesized by free radical polymerization. It seemed reasonable to us to expect that the gel-type polymer electrolyte based on PVP-co-PMMA may not only sustain the mechanical properties of PMMA-based gel polymer electrolyte but also increase the dissolubility of the lithium salt due to the strong withdrawing group within PVP molecules. As a result, Chapter 5 investigated the interaction behavior and related conductivity of all-solid-state polymer electrolyte based on LiClO4/PVP-co-PMMA blend systems.
1-6 REFERENCES
1. Weber, N.; Kummer, J. T. Proc. Annu. Power Sources Conf 1967, 21, 37.
2. Whittingham, M. S.; Huggins R. A. J. Chem. Phys. 1971, 54, 414.
3. Owens, B. B.; Argue, A. G. Science 1967, 157, 308.
4. Takahashi, T.; Ikeda, S.; Yamamoto, O. J. Electrochem. Soc. 1972, 119, 477.
5. Tatsumisago, M.; Shinkuma, Y.; Minami, T. Nature 1991, 354, 217.
6. Nicholson, P. S.; Whittingham, M. S.; Farrington, G. C.; Smeltzer, W. W.; Thomas J., Eds. Solid State Ionics; North-Holland: Amsterdam, 1992.
7. Chowdari, B. V. R.; Chandra, S.; Singh, S.; Srivastava, P. C., Eds. Solid State Ionics, Materials and Appications; North-Holland; Amsterdam, 1992.
8. Bange, K.; Gambke, T. Adv. Mater. 1990, 2, 10.
9. Visco, S. J.; Liu, M.; Doeff, M. M.; Ma, Y. P.; Lampert, C.; De Jonghe, C. Solid State Ionics 1993, 60, 175.
10. Hagenmuller, P.; Van Gool, W., Eds. Solid Electrolytes, General Principles, Characterization, Materials, Applications; Academic Press: New York, 1978.
11. Vincent, C. A.; Bonino, F.; Lazzari, M.; Scrosati, B., Eds. Modern Batteries;
Edward Arnold: London, 1983.
12. Gabano, F., Ed. Lithium Batteries; Academic Press: London, 1983.
13. Rickert, H. Angew. Chem. Int. Ed. Engl. 1978, 17, 37.
14. Bonino, F.; Ottaviani, M.; Scrosati, B. Pistoia, G. J. Electrochem. Soc. 1998, 135, 12.
15. Ratner, M. A.; Shriver, D. F. Chem. Rev. 1988, 88, 109.
16. Gray, F. M. Ed. Solid Polymer Electrolytes: Fundamentals and Technological Applications; VCH: New York, 1991.
17. Fenton, D. E.; Parker, J. M.; Wright, P. V. Polymer 1973, 14, 589.
18. Armand, M.; Duclot, M. French Patent 1978, 7832976.
19. Armand, M. Solid State Ionics 1994, 69, 309.
20. Vögtle, F.; Weber, E. In Crown Ethers and Analogs, Patai, S., Rappoport, Z., Eds.;
Wiley: New York, 1989.
21. Bruce, P. G.; Vincent, C. A. Faraday Discuss. Chem. Soc. 1989, 88, 43.
22. Takeoka, S.; Ohno, H.; Tsuchida, E. Polym. Adv. Technol. 1993, 4, 53.
23. Müller-Plathe, F.; Van Gunsteren, W. F. J. Chem. Phys. 1995, 103, 4745.
24. Gray, F. M.; MacCallum, J. R.; Vincent, C. A. Solid State Ionics 1985, 18–19, 282.
25. LaNest, J. F.; Cheradame, H.; Dalard, F.; Deroo, D. J. Appl. Electrochem. 1986, 16, 75.
26. Gutmann, V., The Donor Acceptor Approach to Molecular Interactions; Plenum Press: New York, 1978.
27. Shotenshtein, A. I.; Petrov, E. S.; Yokovlevla, E. A. J. Polym. Sci., Part C 1967, 16, 1799.
28. Vincent, C. A.; MacCallum, J. R. In Polymer Electrolyte Reviews; Mac Callum, J.
R., Vincent, C. A., Eds., Elsevier: London, 1987.
29. Armand, M. B.; Chabagno, J. M.; Duclot, M. J. In Fast Ion Transport in Solids;
Duclot, M. J., Vashishta, P., Mundy, J. N., Shenoy, G. K., Eds.; North-Holland:
New York, 1979.
30. Shriver, D. F.; Papke, B. L.; Ratner, M. A.; Dupon, R.; Wong, T.; Brodwin, M.
Solid State Ionics 1981, 5, 83.
31. Paper, B. L.; Ratner, M. A.; Shrever, D. F. J. Phys. Chem. Solids 1981, 42, 493.
32. Paper, B. L.; Ratner, M. A.; Shrever, D. F. J. Electrochem. Soc. 1982, 129, 1694.
33. Armand, M. B. Solid State Ionics 1983, 9–10, 745.
34. Watanabe, M.; Rikukawa, M.; Sanui, K.; Ogata, N.; Kato, H.; Kobayashi, T.;
Ohtaki, Z. Polymer J. 1983, 15, 65.
35. Watanabe, M.; Togo, M.; Sanui, K.; Ogata, N.; Kobayashi, T.; Ohtaki, Z.
Macromolecules 1984, 17, 2908.
36. Watanabe, M.; Rikukawa, M.; Sanui, K.; Ogata, N.; Kato, H.; Kobayashi, T.;
Ohtaki, Z. Macromolecules 1984, 17, 1902.
37. Dupon, R.; Papke, B. L.; Ratner, M. A.; Shriver, D. F. J. Electrochem. Soc. 1987, 131, 586.
38. Armstrong, R. D.; Clarke, M. D. Electrochim. Acta. 1984, 29, 1443.
39. Harris, C. S.; Shriver, D. F.; Ratner, M. A. Macromolecules 1986, 19, 987.
40. Clancy, S.; Shriver, D. F.; Ochrymomycz, L. A. Macromolecules 1986, 19, 606.
41. Angell, C. A.; Liu, C.; Sanchez, E. Nature 1993, 362, 137.
42. Armand, M. B.; Chabagno, J. M.; Duclot, M. J. In Extended Abstract Second International Meeting on Solid Electrolytes, St Andrews, Scotland, 20–22 Sept., 1978.
43. Takahashi, Y.; Takadoro, H. Macromolecules 1983, 6, 672.
44. Nagaoka, K.; Naruse, H.; Shinohara, I. Watanabe, M. J. Polym. Sci., Polym. Lett.
Ed. 1984, 22, 659.
45. Hall, P. G.; Davis, G. R.; McIntyre, J. E.; Ward, I. M.; Banister, D. J.; Le Brocq, K.
M. F. Polym. Commun. 1986, 27, 98.
46. Fish, D.; Khan, I. M.; Smid, J. Macromol. Chem. Rapid Commun. 1986, 7, 115.
47. Fish, D.; Khan, I. M.; Smid, J. Br. Polym. J. 1988, 20, 281.
48. Blonsky, P. M.; Shriver, D. F.; Austin, P.; Allcock, H. R. J. Am. Chem. Soc. 1984, 106, 6854.
49. Inoue, K.; Nishikawa, Y.; Tanigaki, T. Marcomolecules 1991, 24, 3464.
50. Blonsky, P. M.; Shriver, D. F. J. Am. Chem. Soc. 1984, 106, 6854.
51. Watanabe, M.; Kanba, M.; Nagaoka, K.; Shinohara, I. J. Polym. Sci., Polym. Phys.
Ed. 1983, 21, 939.
52. Abraham, K. M.; Alamgir, M. J. Electrochem. Soc. 1990, 137, 1657.
53. Abraham, K. M.; Alamgir, M. Solid State Ionics 1994, 70, 20.
54. Matsumoto, M.; Rutt, S. J.; Nishi, S. J. Electrochem. Soc. 1995, 142, 3052.
55. Matsumoto, M.; Ichino, T.; Rutt, S. J.; Nishi, S. J. Electrochem. Soc. 1993, 140, L151.
56. Matsumoto, M.; Ichino, T.; Rutt, S. J.; Nishi, S. J. Electrochem. Soc. 1994, 141, 1989.
57. Matsumoto, M.; Ichino, T.; Rutt, S. J.; Nishi, S. J. Polym. Sci., Polym. Chem. Ed.
1994, 32, 2551.
ceramic framework materials soft framework materials polymersa
crystalline species glasses crystalline species glasses partly crystalline amorphous LiAlSiO4 LiAlSiO4 (glass) AgI AgCl/AgI/CsCl
β-alumina [(Na2O)x‧11Al2O3] Ag2xGeSe2+x Ag2HgI4 LiSCN PEO‧ LiSCN-MEEP
PbI2 NaCF3SO3‧PEI
Na2SO4 NaCF3SO3‧PPO
a PEO = poly(ethylene oxide), PEI = poly(ehylenimine), MEEP = poly(bis(methoxyethoxyethoxy)phosphazene), and PPO = poly(propylene oxide).
Table 1-1. Classes of Solid Electrolytes
Table 1-2. Salts That Form Complex Polymeric Electrolytes with PEOa
a The numbers reported are the lattice energies of the salts (in kJ/mol). “Yes” indicates polymer-salt complex formation and “no” indicates the lack of complex formation.
The stair-step line indicates the division between complex formation and separate phases.
Table 1-3. The Important Parameter for Salt Solubilities
common solvents DN AN
Acetonitrile 14.1 18.9
Propylene carbonate 15.5 18.3
Methanol 19.1 41.5
1,2-Dimethoxyethane (glyme) 22.0 10.2 Tetrahydrofuran (THF) 20.0 8.0
Water 16.4 54.8
Table 1-4. Conductivity Data for Polymer Electrolytes Containing Linear Polymers [33-40]
polymers metal salts
O/Li
2. poly(β-propiolactone)
* CH2 CH2 C O
a The number in the bracket indicates the measured temperature in Kevin unit. b O/Na ratio. c O/Ag ratio.
Table 1-5. Chemical Structures of Common PEO-derivative Materials for Solid Polymer Electrolytes [44-49]
compounds molecular structure reference 1
a MEEP = poly(bis(methoxyethoxyethoxy)phosphazene)
Table 1-6. The Properties of Common Use of Organic Solvents for Gel-type Polymer
Density, g/cm3 0.887 1.198 1.322 1.071 0.98 Solution
a THF = tetrahydrofuran, PC = propylene carbonate, EC = ethylene carbonate, DMC
= dimethyl carbonate, DEC = diethyl carbonate.
Table 1-7. Conductivity Data for Gel-type Polymer Electrolytes [51-57]
gel polymers Li salt maximum conductivity, S cm-1 reference NBR/SBR/BLa LiClO4 1.2 × 10-3 (298)e [54]
PAN/ECb/PCc LiClO4 1.7 × 10-3 (293) [53]
PAN/PC LiClO4 2.0 × 10-4 (293) [51]
EC/PC/PAN/PEGDAd LiClO4 4.0 × 10-4 (263); 1.2 × 10-3 (293) [55]
EC/PC/PAN LiCF3SO3 4.0 × 10-4 (263); 1.4 × 10-3 (293) [56]
EC/PC/PVP LiCF3SO3 4.0 × 10-5 (263); 5.0 × 10-4 (293) [57]
a BL = γ-butyrolactone, b EC = ethylene carbonate, c PC = propylene carbonate, d PEGDA = poly(tetra ethylene glycol diacrylate), e The number in the bracket indicates the measured temperature in Kevin unit.
Figure 1-1. Comparison of the different battery technologies in terms of volumetric and gravimetric energy density. The share of worldwide sales for Ni-Cd, Ni-MeH and Li-ion portable batteries is 23, 14, 63 %, respectively. The use of Pb-acid batteries is restricted mainly to SLI (starting, lighting, ignition) in automobiles or standby applications, whereas Ni-Cd batteries remain the most suitable technologies for high-power applications.
Figure 1-2. Schematic illustration of a lithium rocking chair battery with graphite and spinel as intercalation electrodes and its electrode reactions.
Figure 1-3. Schematic of the segmental motion assisted diffusion of Li+ in the PEO matrix. The circles represent the ether oxygen atoms of PEO.
19.3 Å
Figure 1-4. The helical structure of PEO molecule [43].