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首页> 外文期刊>RSC Advances >Strategies for fast ion transport in electrochemical capacitor electrolytes from diffusion coefficients, ionic conductivity, viscosity, density and interaction energies based on HSAB theory
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Strategies for fast ion transport in electrochemical capacitor electrolytes from diffusion coefficients, ionic conductivity, viscosity, density and interaction energies based on HSAB theory

机译：基于HSAB理论的扩散系数，离子电导率，粘度，密度和相互作用能在电化学电容器电解质中快速离子迁移的策略

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摘要

To elucidate factors affecting ion transport in capacitor electrolytes, five propylene carbonate (PC) electrolytes were prepared, each of which includes a salt ((C2H5)4NBF4, (C2H5)4NPF6, (C2H5)4NSO3CF3, (C2H5)3CH3NBF4 and LiBF4). In addition to conventional bulk parameters such as ionic conductivity (σ), viscosity (η) and density (ρ), self-diffusion coefficients (D) of the cation, anion and PC were measured by pulsed-gradient spin-echo (PGSE) NMR. Interaction energies (ΔE) were calculated by density function theory calculations based on Hard and Soft Acids and Bases (HSAB) theory for cation–anion (salt dissociation) and solvent–cation/anion (solvation). ΔE values are related to the salt dissociation and solvation, which affect ion diffusion radii formed by solvation and/or ion pairs. The calculated solvation ΔE values were small (around 0.30 eV) and salt dissociation energies were also small. For comparison, the ΔE value for PC–Li+ interaction was larger than that for ammonium cations, because of strong Li+ Lewis acidity. Ammonium salts are highly dissociated and each ion forms a weakly solvated structure, which is quite different from Li+ electrolytes. Weak solvation for the cation and anion in the ammonium salts are important in enhancing fast ion transfer and electrode reactions in capacitor devices.
机译：为阐明影响电容器电解质中离子迁移的因素，制备了五种碳酸亚丙酯（PC）电解质，每种电解质都包含一种盐（（C 2 H 5 ） 4 NBF 4 ，（C 2 H 5 ） 4 NPF 6 ，（C 2 H 5 ） 4 NSO 3 CF 3 ，（C 2 H 5 ） 3 CH 3 NBF 4 和LiBF 4 ）。除了常规的体积参数，例如离子电导率（σ），粘度（η）和密度（ρ），自扩散系数（阳离子，阴离子和PC的 D ）通过脉冲梯度自旋回波（PGSE）NMR进行测量。相互作用能（Δ E ）是根据密度函数理论计算得出的，该函数基于硬质和软质酸和碱（HSAB）理论，用于阳离子-阴离子（盐离解）和溶剂-阳离子/阴离子（溶剂化）。 Δ E 值与盐解离和溶剂化有关，盐解离和溶剂化会影响由溶剂化和/或离子对形成的离子扩散半径。计算得到的溶剂化Δ E 值很小（约0.30 eV），盐解离能也很小。为了比较，PC-Li + 相互作用的Δ E 值大于铵阳离子的Δ E ，这是由于Li < sup> + 路易斯酸度。铵盐高度解离，每个离子形成弱溶剂化的结构，这与Li + 电解质完全不同。铵盐中阳离子和阴离子的弱溶剂化对于增强电容器器件中的快速离子转移和电极反应非常重要。

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