Influence of anion structure on ion dynamics in polymer gel electrolytes composed of poly(ionic liquid), ionic liquid and Li salt
Influence of anion structure on ion dynamics in polymer gel electrolytes composed of poly(ionic liquid), ionic liquid and Li salt
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DOI：
10.1016/j.electacta.2017.03.219
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发表时间：
2017-05-20
影响因子：
6.6
通讯作者：
Schoenhoff, Monika
中科院分区：
文献类型：
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作者：
Brinkkoetter, Marc;Lozinskaya, Elena I.;Schoenhoff, Monika
为了研究阴离子结构对电解液物理性质的影响，我们使用了5种阴离子，即(FSO2)(2)N(FSI，FSA)，(CN)(2)N(DCA)，(CF3SO2)(2)N(TFSI，TFSA)，CF3SO3(TFO)和(CF3SO2)N(CN)(TFSAM)，并分别在一系列聚电解质、离子液体(IL)/Li盐混合物和三元离子凝胶(聚(离子液体)/离子液体/Li盐)中进行了研究。聚离子液体(PIL)、聚二烯丙基二甲基铵(PDADMA)和所用离子液体都含有相同的吡咯烷阴离子。为了单独分离阴离子的影响，使用了一种常见的氯化物前体PIL来保持平均聚合度(DPN)和链分散性的恒定。从离子导电性、电化学稳定性与Li+/Li、离子扩散(多核脉冲电场梯度核磁共振)和局部锂离子动力学(Li-7自旋晶格驰豫速率)等方面进行了分析。对于这些参数的优化，得到了阴离子系列的不同级数，并从结构和离子配位的角度进行了讨论。特别是，-CN基团对锂离子的配位强度高于-SO2CF3片段中氧的配位强度。因此，TFSAM样品中的锂离子主要由-CN基团配位。详细的结构/性能关系分析表明，对于离子凝胶(电容器、传感器等)的这些应用来说，如果主要要求高电导率，而电化学稳定性不是必需的，则FSI阴离子将是最佳选择。然而，对于储能系统，如锂金属电池，最好是TFSI，但也包括TFSAM阴离子将代表相关参数的最佳折衷。(C)2017爱思唯尔有限公司。保留所有权利。
To investigate the influence of anion structure on physical properties of electrolytes we used five different anions, namely (FSO2)(2)N (FSI, FSA), (CN)(2)N (DCA), (CF3SO2)(2)N (TFSI, TFSA), CF3SO3 (TfO) and (CF3SO2)N(CN) (TFSAM), and investigated them in a series of polyelectrolytes, ionic liquid (IL)/Li salt mixtures and in ternary ion gels (poly(ionic liquid)/ionic liquid/Li salt), respectively. Both the poly(ionic liquid) (PIL) poly(diallyldimethylammonium) (PDADMA) and the ILs employed in the study have the same pyrrolidinium anion. To isolate solely the effect of the anion a common chloride precursor PIL was used to maintain constant the average degree of polymerization (DPn) and chain dispersity. The systems were analyzed in terms of ionic conductivity, electrochemical stability vs Li+/Li, ion diffusion (multinuclear Pulsed Field Gradient NMR) and local lithium ion dynamics (Li-7 spin lattice relaxation rates). Concerning optimization of any of these parameters, different orders of the anion series are obtained and discussed in terms of structural aspects and ion coordination. In particular, the coordination strength of the -CN group to the lithium ion is higher than the coordination strength of the oxygens of the -SO2CF3 fragment. As a result the lithium ion in the TFSAM samples is primarily coordinated by the -CN group. Detailed structure/property relationship analysis demonstrated that for those applications of ion gels (capacitors, sensors, etc.) where a high conductivity is a primary demand, while the electrochemical stability is not essential, the FSI anion will be the best choice. However, for energy storage systems such as Li metal batteries preferably TFSI but also TFSAM anions will represent the best compromise of relevant parameters. (C) 2017 Elsevier Ltd. All rights reserved.