Los Alamos National Laboratory, Los Alamos, New Mexico, New Mexico 87545, USA.
J Chem Phys. 2010 Jan 28;132(4):044701. doi: 10.1063/1.3294560.
Dielectric characteristics of a molecular model of liquid propylene carbonate are evaluated for utilization in molecular scale simulation of electrochemical capacitors based on nanotube forests. The linear-response dielectric constant of the bulk liquid, and its temperature dependence, is in good agreement with experiment. Dielectric saturation is studied by simulations with static uniform electric fields as large as 4 V/nm. The observed polarization is well described by the Langevin equation with the low-field/high-field crossover parameter of 0.09 V/nm. Simulation of liquid propylene carbonate confined between charged parallel graphite electrodes yields a capacitance that depends on the electric potential difference across those thin films. An effective dielectric constant inferred from the capacitance is significantly less than the uniform liquid dielectric constant, but is consistent with the nonlinear dielectric response at the strong fields applied to the electrode film. Those saturation effects reduce the weak-field capacitance.
用于基于纳米管森林的电化学电容器的分子尺度模拟的液体碳酸丙烯酯分子模型的介电特性进行了评估。 液体的线性响应介电常数及其温度依赖性与实验很好地吻合。 通过模拟静态均匀电场高达 4 V/nm 研究了介电饱和。 观察到的极化很好地用 Langevin 方程描述，低场/高场交叉参数为 0.09 V/nm。 在带电平行石墨电极之间限制的液体碳酸丙烯酯的模拟产生了取决于这些薄膜之间的电势差的电容。 从电容推断的有效介电常数明显小于均匀液体介电常数，但与施加到电极膜的强场的非线性介电响应一致。 这些饱和效应降低了弱场电容。
