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电化学 ›› 2021, Vol. 27 ›› Issue (6): 646-657.  doi: 10.13208/j.electrochem.210210

• 研究论文与评述 • 上一篇    下一篇

多孔电极电池的循环伏安法模拟

蔡雪凡, 孙升*()   

  1. 上海大学材料基因组工程研究院,上海 200444
  • 收稿日期:2021-02-10 修回日期:2021-04-07 出版日期:2021-12-28 发布日期:2021-04-14
  • 通讯作者: 孙升 E-mail:mgissh@t.shu.edu.cn
  • 基金资助:
    国家自然科学基金项目(12072179);国家自然科学基金项目(11672168)

Cyclic Voltammetric Simulations on Batteries with Porous Electrodes

Xue-Fan Cai, Sheng Sun*()   

  1. Materials Genome Institute, Shanghai University, Shanghai 200444, China
  • Received:2021-02-10 Revised:2021-04-07 Online:2021-12-28 Published:2021-04-14
  • Contact: Sheng Sun E-mail:mgissh@t.shu.edu.cn

摘要:

锂离子电池的全电池建模模拟对现代新能源领域的发展至关重要。伪二维(P2D)电化学模型是最常使用的全电池模拟模型,但一直被用于输入为电流,输出为电压的模拟中。本文基于P2D模型,通过对内电位、电极电位以及电池端电压的详细讨论,首次采用电压边界条件,利用COMSOL仿真软件完成了实验中常用的两电极体系和三电极体系的循环伏安法建模和模拟。并对比分析了两/三电极体系中扫描速率、颗粒半径、电极锂扩散速率以及最大嵌锂浓度这四个参数对循环伏安曲线形状的影响。结果表明,循环伏安测试时扫描速率越大,循环伏安曲线的峰值电流越大;固相锂扩散速率越大、电活性颗粒半径越小、最大嵌锂浓度越大,峰值电流越大。在相同的测试条件下,三电极体系比两电极体系的循环伏安图对称性更好,电流响应更大,并且颗粒半径、锂扩散速率及最大嵌锂浓度这三个参数对峰值电流的影响也更为明显。

关键词: 锂离子电池, 循环伏安法, P2D模型, 两/三电极体系, COMSOL仿真模拟

Abstract:

Lithium-ion batteries (LIBs) are among the most widely used energy storage devices. Whole-cell modeling and simulations of LIBs can optimize the design of batteries with lower costs and higher speeds. The Pseudo-Two-Dimensional (P2D) electrochemical model is among the most famous whole-cell models and widely applied in LIB simulations. P2D model consists of a series of kinetic equations to model Li+/Li diffusion in working/counter electrodes and electrolytes, which are filled in the porous electrodes and separator, and reactions at the interface of electrolyte and active particles. The traditional applications of P2D model, however, are limited to the cases where the current is the control variable and the voltage is the dependent variable. The present work tries to apply boundary conditions with the electrode potential as the control variable to simulate cyclic voltammetric (CV) experiments on the whole battery, based on a detailed analysis on different potentials, including Galvani potential, Volta potential, electrode potential and battery terminal voltage, as well as their relationships. In many CV experiments, only two electrodes, the working and the counter electrodes, are used. The experimental results are usually explained by using theoretical results directly taken from textbooks. The theories of CV are, however, based on three-electrode systems with a reference electrode to provide a reference voltage. The differences of CV curves between the two- and the three-electrode systems have never been studied by using P2D models. The present work performs numerical simulations of CV on both two- and three-electrode systems by using finite element methods, brought with the software of COMSOL Multiphysics, to study the influences of scanning rate, effective radius of active particles, lithium ion diffusivity and stoichiometric maximum concentration in electrode on CV curves. The three-electrode system is simulated by applying a potential detector at the separator region of a battery. The applied potentials are changed in time based on the magnitude of the detected potential. Results show that, for CV curves on both two- and three-electrodes systems, the peak current determined by the complex electrode dynamics process increases with the increases of scanning rate, lithium ion diffusivity in electrode and stoichiometric maximum lithium ion concentration, but with the decrease of the radius of electrode active particles. The peak currents obtained from CV curves are larger in three-electrode systems than in two-electrode systems under the same applied parameters. CV curves of three-electrode systems are more symmetric for the anodic and cathodic currents than those in two-electrode systems.

Key words: lithium ion battery, cyclic voltammetry, P2D model, two/three electrode system, finite element simulation