Blends of POSS-PEO(n=4)(8) and high molecular weight poly(ethylene oxide) as solid polymer electrolytes for lithium batteries.
Blends of POSS-PEO(n=4)(8) and high molecular weight poly(ethylene oxide) as solid polymer electrolytes for lithium batteries.
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DOI：
10.1021/jp064585g
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发表时间：
2007-03
期刊：
影响因子：
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通讯作者：
Hanjun Zhang;Sunil Kulkarni;S. Wunder
中科院分区：
文献类型：
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作者：
Hanjun Zhang;Sunil Kulkarni;S. Wunder
以POSS-PEO（n=4）8（3 K）、聚环氧乙烷（PEO（600 K））和LiClO 4为原料，在不同盐浓度（O/Li = 8/1、12/1和16/1）下制备了固体聚合物电解质共混物。POSS-PEO（n=4）_8/LiClO_4在所有的O/Li下均为非晶态，而PEO（600 K）在O/Li = 8/1时为非晶态，在O/Li = 12/1和16/1时为半晶态。PEO（600 K）结晶的倾向限制了可以掺入共混物中的POSS-PEO（n=4）（8）的量，使得POSS-PEO（n=4）（8）的最大掺入发生在O/Li = 8/1时。POSS-PEO（n=4）（8）/PEO（600 K）/LiClO 4（O/Li = 8/1和12/1）微相共混物分离成两个非晶相，组成为85% POSS-PEO（n=4）（8）/15%PEO（600 K）的低T（g）相和组成为29% POSS-PEO（n=4）（8）/71%PEO（600 K）的高T（g）相。当O/Li = 16/1时，共混物含有结晶相（纯PEO（600 K））和两个非晶相，一个富含POSS-PEO（n=4）（8），一个富含PEO（600 K）。微相，而不是大相分离被认为是由于Li（+）/醚氧交联位点而发生的。共混物的导电性取决于它们的组成。正如预期的那样，结晶度降低了共混物的电导率。对于无定形共混物，当低T（g）（80/20）相为连续相时，电导率介于纯PEO（600 K）和POSS-PEO（n=4）（8）之间。当高T（g）（70/30、50/50、30/70和20/80）相为连续相时，共混物和PEO（600 K）的电导率相同，并且在整个温度范围（10-90 ℃）内低于POSS-PEO（n=4）（8）的电导率。这表明POSS-PEO（n=4）（8）的运动被长链PEO（600 K）的动力学减慢，并且次要的低Tg相没有相互连接，因此对增强的电导率没有贡献。在高于PEO的T（m）（600 K）的温度下，POSS-PEO（n=4）（8）的添加没有导致电导率的改善。60% POSS-PEO（n=4）（8）/40%PEO（600 K）/LiClO_4（O/Li = 12/1）共混物的室温电导率最高，为8 × 10 ~（-6）S/cm。
Solid polymer electrolyte blends were prepared with POSS-PEO(n=4)8 (3K), poly(ethylene oxide) (PEO(600K)), and LiClO4 at different salt concentrations (O/Li = 8/1, 12/1, and 16/1). POSS-PEO(n=4)8/LiClO4 is amorphous at all O/Li investigated, whereas PEO(600K) is amorphous only for O/Li = 8/1 and semicrystalline for O/Li = 12/1 and 16/1. The tendency of PEO(600K) to crystallize limited the amount of POSS-PEO(n=4)(8) that could be incorporated into the blends, so that the greatest incorporation of POSS-PEO(n=4)(8) occurred for O/Li = 8/1. Blends of POSS-PEO(n=4)(8)/PEO(600K)/LiClO4 (O/Li = 8/1 and 12/1) microphase separated into two amorphous phases, a low T(g) phase of composition 85% POSS-PEO(n=4)(8)/15% PEO(600K) and a high T(g) phase of composition 29% POSS-PEO(n=4)(8)/71% PEO(600K). For O/Li = 16/1, the blends contained crystalline (pure PEO(600K)), and two amorphous phases, one rich in POSS-PEO(n=4)(8) and one rich in PEO(600K). Microphase, rather than macrophase separation was believed to occur as a result of Li(+)/ether oxygen cross-link sites. The conductivity of the blends depended on their composition. As expected, crystallinity decreased the conductivity of the blends. For the amorphous blends, when the low T(g) (80/20) phase was the continuous phase, the conductivity was intermediate between that of pure PEO(600K) and POSS-PEO(n=4)(8). When the high T(g) (70/30, 50/50, 30/70, and 20/80) phase was the continuous phase, the conductivity of the blend and PEO(600K) were identical, and lower than that for the POSS-PEO(n=4)(8) over the whole temperature range (10-90 degrees C). This suggests that the motions of the POSS-PEO(n=4)(8) were slowed down by the dynamics of the long chain PEO(600K) and that the minor, low Tg phase was not interconnected and thus did not contribute to enhanced conductivity. At temperatures above T(m) of PEO(600K), addition of the POSS-PEO(n=4)(8) did not result in conductivity improvement. The highest RT conductivity, 8 x 10(-6) S/cm, was obtained for a 60% POSS-PEO(n=4)(8)/40% PEO(600K)/LiClO4 (O/Li = 12/1) blend.