3类锂离子电池多孔电极模型比较研究及电池正向设计应用  

Comparison study of three porous electrode models for the forward design of lithium-ion batteries

作　　者：方儒卿 张娜[1] 李哲[1] FANG Ruqing;ZHANG Na;LI Zhe(State Key Laboratory of Automotive Safety and Energy,Tsinghua University,Beijing 100084,China)

机构地区：[1]清华大学汽车安全与节能国家重点实验室,北京100084

出　　处：《清华大学学报（自然科学版）》2021年第10期1055-1065,共11页Journal of Tsinghua University(Science and Technology)

基　　金：国家重点研发计划项目(2017YFB0102201)

摘　　要：锂离子电池的电极由活性物质、黏结剂、导电剂等多种固相材料及灌注其孔隙间的液态电解质组成。通过优化电极的微观多孔结构可提高电池内部锂离子与电子两类主要载流子的有效传输速率,从而有效提升电池能量密度、功率密度。基于多孔电极模型的正向设计方法正逐渐取代传统的试错方法被广泛应用于产业界,但以往的模型难以在计算量与性能预测精度上取得平衡。该文提出了扩展均相多孔电极模型,该模型可以有效地在计算负荷与性能预测精度上实现较好的平衡。比较了3类锂离子电池多孔电极模型——经典准二维均相模型、作者团队开发的非均相模型、该文提出的扩展均相多孔电极模型在计算时间以及电极结构描述精度上的差异,并就不同研发场景下的模型选择给出了具体建议。利用扩展均相多孔电极模型分析了一例电池正向设计的典型问题,即负极活性颗粒粒径选择及其对电池性能的影响,结果发现:提高负极颗粒粒径分布集中度、降低颗粒粒径大小可有效改善电池内部离子在电解液以及活性颗粒内部的有效传输速率,可使得电池在不同倍率条件下的放电容量提升25%(低倍率)至100%(高倍率)。The electrodes of lithium ion batteries are composed of active material particles, binders, conductive additives and pores filled with electrolyte. Optimizing the porous structure of the electrode effectively improves the ionic and electronic transport inside the cell which improves the battery power output. Many previous designs have used the conventional trial-and-error method while the forward design method based on an electrode model is gradually being more widely used in the industry. However, previous electrode models required excessive computations to get the desired prediction accuracy. This paper presents an extended homogeneous porous electrode model for lithium-ion batteries which balances the computational cost and the prediction accuracy. This study compares the computational costs and the electrode modeling accuracy of three electrode models, a traditional volume-averaged pseudo 2 D model, a 2 D heterogeneous particle-packing model from the previous work of the authors’ group, and the extended homogeneous model of this study. Then, this paper discusses how these three electrode models can be used for the forward design of lithium-ion battery electrodes. Finally, the extended homogeneous model is used to analyze the influence of the particle size distribution in the negative electrodes on the cell rate performance with improvements of up to 25% for low C-rates to 100 % for high C-rates produced by narrowing the particle size distribution and reducing the particle size.

关 键 词：锂离子电池 电化学模型 多孔电极 非均相模型 粒径分布 

分 类 号：TM9129[电气工程—电力电子与电力传动]