结晶型PEO8∶NaPF6聚电解质中晶区链段的运动
收稿日期: 2014-04-04
修回日期: 2015-01-08
网络出版日期: 2015-03-05
基金资助
国家自然科学基金资助项目(11004220，11274347).
Segmental Motion of PEO8∶NaPF6 Crystalline Polymer Electrolyte
Received date: 2014-04-04
Revised date: 2015-01-08
Online published: 2015-03-05
Supported by
国家自然科学基金资助项目(11004220，11274347).
利用固体NMR 研究了高度结晶的聚氧乙烯(PEO)/六氟磷酸钠(NaPF6)（按照氧钠摩尔比8∶1 描述为PEO8∶NaPF6，分子量Mw = 1 000 和6 000 g/mol）固体聚电解质晶区链段的结构和运动．对于纯PEO 来说，晶区链段的构象交换或大角度再取向促使其13C 粉末线形从低温的非轴对称(δ33 < δ22 < δ11)变成高温的轴对称线形(δ11 =δ22 > δ33)．通过变温的13C 粉末线形和243 K 下的二维交换谱，PEO8∶NaPF6 晶区链段同样存在大角度再取向，且开启温度也很低(~243 K)与PEO 接近．这种长程的运动使得PEO8∶NaPF6 从低温的类轴对称(δ33 < δ22 < δ11)变成高温的轴对称线形(δ33 > δ22 = δ11)，高温线形是PEO 高温线形的翻转．与其它PEO/Na(Li)固体聚电解质不同，PEO8∶NaPF6 中晶区链段与Na+络合后仍具有很高的运动性（与纯PEO 链段的运动性相当），这种高分子链段和Na+协同运动促使Na+沿PEO 分子链轴向迁移，提高电导率．
罗 欢1 , 2 , 梁欣苗1 , 2 , 冯继文1 , 王立英1 . 结晶型PEO8∶NaPF6聚电解质中晶区链段的运动[J]. 波谱学杂志, 2015 , 32(1) : 12 -22 . DOI: 10.11938/cjmr20150102
Solid-state NMR spectroscopy was used to study the segmental motion of high-crystallinity PEO8∶NaPF6 electrolytes with different PEO molecular weights (Mw =1 000 and 6 000 g/mol, respectively). 13C-magic angle spinning (MAS) NMR spectra and static powder patterns, as well as static 2D exchange spectra, revealed that large-angle reorientation of the crystalline PEO segments in both PEO8∶NaPF6 complexes starts at a very low temperature (~243 K), similar to the case in pure crystalline PEO. At higher temperature, long-range reorientation gives rise to a well-defined high-temperature powder pattern of uniaxial chemical shift anisotropy (δ33 > δ22 = δ11), perhaps as the result of flipping of PEO. In contrast to other PEO/Na (Li) solid electrolytes, the segments in crystalline PEO8∶NaPF6 are highly mobile even when coordinated with Na+, and this is comparable with PEO. It is suggested that the segmental motion in crystalline PEO8∶NaPF6 electrolyte can enhance ion transportation along the coil, improving ionic conductivity.
Key words： solid-state NMR; polymer dynamics; ionic conductivity; PEO; PEO8∶NaPF6
[1] Tarascon J M, Armand M. Issues and challenges facing rechargeable lithium batteries [J]. Nature, 2001, 414(6 861): 359－367.
[2] Fenton D E, Parker J M, Wright P V. Complexes of alkali-metal ions with poly(ethylene oxide) [J]. Polymer, 1973, 14(11): 589－589.
[3] Berthier C, Gorecki W, Minier M, et al. Microscopic investigation of ionic-conductivity in alkali-metal salts poly(ethylene oxide) adducts[J]. Solid State Ionics, 1983, 11(1): 91－95.
[4] Ratner M A, Shriver D F. Ion-transport in solvent-free polymers[J]. Chem Rev, 1988, 88(1): 109－124.
[5] Borodin O, Smith G D. Mechanism of ion transport in amorphous poly(ethylene oxide)/LiTFSI from molecular dynamics simulations[J]. Macromolecules, 2006, 39(4): 1 620－1 629.
[6] Croce F, Appetecchi G B, Persi L, et al. Nanocomposite polymer electrolytes for lithium batteries[J]. Nature, 1998, 394(6 692): 456－458.
[7] Dissanayake M A K L, Frech R. Infrared spectroscopic study of the phases and phase-transitions in poly(ethylene oxide) and poly(ethylene oxide)-lithium trifluoromethanesulfonate complexes[J]. Macromolecules, 1995, 28(15): 5 312－5 319.
[8] Frech R, Chintapalli S, Bruce P G, et al. Crystalline and amorphous phases in the poly(ethylene oxide)-LiCF3SO3 system[J]. Macromolecules, 1999, 32(3): 808－813.
[9] Cha E H, Lim S A, Lee C W, et al. Ionic conductance of PDMAEMA/PEO polymeric electrolyte containing lithium salt mixed with plasticizer[J]. J Power Sources, 2006, 163(1): 269－273.
[10] Sannier L, Bouchet R, Grugeon S, et al. Room temperature lithium metal batteries based on a new gel polymer electrolyte membrane[J]. J Power Sources, 2005, 144(1): 231－237.
[11] Wright P V. Polymer electrolytes - the early days[J]. Electrochim Acta, 1998, 43(10-11): 1 137－1 143.
[12] Gadjourova Z, Andreev Y G, Tunstall D P, et al. Ionic conductivity in crystalline polymer electrolytes[J]. Nature, 2001, 412(6 846): 520－523.
[13] Rocco A M, Carias A D, Pereira R P. Polymer electrolytes based on a ternary miscible blend of poly(ethylene oxide), poly(bisphenol A-co-epichlorohydrin) and poly(vinyl ethyl ether)[J]. Polymer, 2010, 51(22): 5 151－5 164.
[14] Bruce P G, Vincent C A. Polymer Electrolytes[J]. J Chem Soc Faraday T, 1993, 89(17): 3 187－3 203.
[15] Christie A M, Lilley S J, Staunton E, et al. Increasing the conductivity of crystalline polymer electrolytes[J]. Nature, 2005, 433(7 021): 50－53.
[16] Henderson W A, Passerini S. Ionic conductivity in crystalline-amorphous polymer electrolytes - P(EO)(6): LiX phases[J]. Electrochem Commun, 2003, 5(7): 575－578.
[17] Stoeva Z, Martin-Litas I, Staunton E, et al. Ionic conductivity in the crystalline polymer electrolytes PEO6 : LiXF6, X = P, As, Sb[J]. J Am Chem Soc, 2003, 125(15): 4 619－4 626.
[18] Vincent C A. Ion-transport in polymer electrolytes[J]. Electrochim Acta, 1995, 40(13-14): 2 035－2 040.
[19] Vincent C A. Polymer electrolytes - new materials for pure and applied electrochemistry - the simulation challenge[J]. Comput Polymer Sci, 1995, 5(3): 81－88.
[20] Zhang C H, Gamble S, Ainsworth D, et al. Alkali metal crystalline polymer electrolytes[J]. Nat Mater, 2009, 8(7): 580－584.
[21] Schmidt-Rohr K, Spiess H W. Multidimensional Solid-State NMR and Polymers[M]. New York: Academic Press, 1994.
[22] Schmidt-Rohr K. Dynamics, structure, and order of polymers studied by multidimensional solid-state NMR[J]. Abstr Pap Am Chem S, 1994, 208, 111: PMSE.
[23] Gao Y W, Hu B W, Yao Y F, et al. Segmental dynamics of PEO/LiClO4 complex crystals and their influence on the Li+-Iontransportation in crystal lattices: A 13C solid-state NMR approach[J]. Chem-Eur J, 2011, 17(32): 8 941－8 946.
[24] Luo H, Liang X, Wang L, et al. Highly mobile segments in crystalline poly(ethylene oxide)(8): NaPF6 electrolytes studied by solid-state NMR spectroscopy[J]. J Chem Phys, 2014, 140(7): 74 901.
[25] Zhang Lei(张磊), Yang Guang(杨光), Chen Qun(陈群). Influence of CP time on intermolecular cross polarization in the composite of poly(ethylene oxide) and fullerene(交叉极化时间对分子间交叉极化的影响的研究)[J]. Chinese J Magn Reson(波谱学杂志), 2005(3): 245－251.
[26] Song Rui(宋瑞), Pan Tie-ying(潘铁英), Shi Xin-mei(史新梅), et al. Coal and its liquefaction products studied by NMR and ESR spectroscopy(煤及其液化产物的13C CP/MAS/TOSS NMR 和ESR 研究)[J]. Chinese J Magn Reson(波谱学杂志), 2006(1): 41－47.
[27] Schmidt-Rohr K, Wilhelm M, Johansson A, et al. Determination of chemical-shift tensor orientations in methylene groups by separated-local-field NMR[J]. Magn Reson Chem, 1993, 31(4): 352－356.
[28] Wei L, Liu Q H, Gao Y W, et al. Phase structure and helical jump motion of poly(ethylene oxide)/LiCF3SO3 rystalline complex: A high-resolution solid-state 13C NMR approach[J]. Macromolecules, 2013, 46(11): 4 447－4 453.
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