Multi-ionic lithium salts comprised of polyoligomeric silsesquioxanes (POSS) functionalized with eight – (LiNSO₂CF₃) groups, referred to as POSS-(LiNSO₂CF₃)₈, can be dissolved at very high loadings into tetraglyme (G₄), where they can be considered solvent-in-salt electrolytes. With increasing dilution, colloidal solutions are formed. Two systems were investigated, neat POSS-(LiNSO₂CF₃)₈ in G₄ and mixtures of POSS-(LiNSO₂CF₃)₈ with LiPF₆ or lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). PFG-NMR indicates that Li can be un-dissociated, completely dissociated and surrounded by G₄ molecules, or as contact ion pairs (in which there are 3–4 ether oxygen contacts and one contact with the oxygen from the anion). Equilibria exist between the species of POSS-(LiNSO₂CF₃)₈ and if there is rapid equilibration between the Li states, and close enough proximity between the POSS-(LiNSO₂CF₃), then the Li⁺ ions can migrate by a Grotthus-type coordinated hopping mechanism, as well as by a purely diffusive motion. Unlike polymer single ion conductors, where the backbone flexibility permits cluster/aggregate formation, which inhibits escape and mobility of the Li⁺ ions, the rigid POSS cube and its colloidal structure in G₄ prevents formation of POSS-(NSO₂CF₃⁻)⋯Li⁺⋯(⁻CF₃NSO₂)-POSS triplets. Instead, the solvated Li⁺ in POSS-(NSO₂CF₃⁻)⋯Li⁺⋯G₄ can be more easily removed to form conductive G₄⋯Li⁺⁻⋯G₄. Good ionic conductivities (∼10⁻⁴ S cm⁻¹) and lithium ion transference numbers of t^PP₊ = 0.65 can be achieved in these systems. Mixtures of 80 wt% LiTFSI and 20 wt% POSS-(LiNSO₂CF₃)₈ in G₄ at an O/Li ratio of 20/1, yield both high conductivity (σ = 3.3 × 10⁻³ S cm⁻¹) and high (t^PP₊ = 0.65) transference number. Stable cycling between C/2 and 2C with high capacity retention was achieved using Li/[G₄/80 wt% LiTFSI/20 wt% POSS-(LiNSO₂CF₃)₈]/LiFePO₄ half-cells.

中文翻译：

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使用多离子盐实现单离子电导率的另一种途径†

包含POSS-（LiNSO ₂ CF ₃）_8的，由八个（LiNSO ₂ CF ₃）基团官能化的低聚倍半硅氧烷（POSS）组成的多离子锂盐，可以以很高的负载量溶解成四甘醇二甲醚（G ₄）。 ，可以将其视为盐中溶剂型电解质。随着稀释度的增加，形成胶体溶液。研究了两个系统：纯净的POSS-（LiNSO ₂ CF ₃）₈在G _4中和POSS-（LiNSO ₂ CF ₃）₈与LiPF _6的混合物或双（三氟甲磺酰基）酰亚胺锂（LiTFSI）。PFG-NMR表明，Li可以未解离，完全解离并被G ₄分子包围，或作为接触离子对（其中有3–4个醚氧接触并且一个与阴离子中的氧接触）。在POSS-（LiNSO ₂ CF ₃）₈的物种之间存在平衡，如果在Li状态之间存在快速平衡，并且在POSS-（LiNSO ₂ CF ₃）之间足够接近，则Li ⁺离子可以通过Grotthus型协调跳跃机制以及纯扩散运动迁移。不同于聚合物单离子导体，其中所述主链的灵活性允许群集/聚集体形成，其抑制逸出和锂的迁移率⁺离子，G中的刚性POSS立方体及其胶体结构₄防止形成POSS-的（NSO ₂ CF ₃ ^- ）⋯Li ⁺ ⋯（⁻ CF ₃ NSO ₂）-POSS三胞胎。取而代之的是，溶剂化的锂⁺在POSS-（NSO ₂ CF ₃ ^-）⋯栗⁺ ⋯ģ ₄可以更容易地除去以形成导电性G ₄ ⋯Li ^{+ −} ⋯G ₄。在这些系统中，可以获得良好的离子电导率（〜10 ^-4 S cm ^-1）和锂离子转移数t ^PP ₊ = 0.65。以20/1的O / Li比在G _4中以80 wt％的LiTFSI和20 wt％的POSS-（LiNSO ₂ CF ₃）_8的混合物产生高电导率（σ = 3.3×10 ^-3 S cm ^-1）高（t ^PP ₊= 0.65）转移编号。使用Li / [G达到C / 2和2C之间稳定的循环具有高容量保持₄ /80重量％的LiTFSI / 20重量％POSS-（林索₂ CF ₃）₈ ] /的LiFePO ₄的半电池。