化工学报 ›› 2021, Vol. 72 ›› Issue (12): 6340-6350.DOI: 10.11949/0438-1157.20210813

• 能源和环境工程 • 上一篇    下一篇

锂离子电池电极中多级孔道结构设计

汪宇1(),张禹2,童微雯1,叶光华1(),周兴贵1,袁渭康1   

  1. 1.华东理工大学化学工程联合国家重点实验室,上海 200237
    2.上海空间推进研究所,上海 201112
  • 收稿日期:2021-06-17 修回日期:2021-09-08 出版日期:2021-12-05 发布日期:2021-12-22
  • 通讯作者: 叶光华
  • 作者简介:汪宇 (1998—),男,硕士研究生,Y30190945@mail.ecust.edu.cn
  • 基金资助:
    国家自然科学基金项目(21676082)

Engineering hierarchical pore network for Li-ion battery electrodes

Yu WANG1(),Yu ZHANG2,Weiwen TONG1,Guanghua YE1(),Xinggui ZHOU1,Weikang YUAN1   

  1. 1.State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China
    2.Shanghai Institute of Space Propulsion, Shanghai 201112, China
  • Received:2021-06-17 Revised:2021-09-08 Online:2021-12-05 Published:2021-12-22
  • Contact: Guanghua YE

摘要:

在较高充放电速率下,锂电池电极中Li+扩散受限严重,致使电池性能显著降低。为了减弱扩散限制,设计电极的孔结构是一种行之有效的方法。本工作以LiCoO2正极为模型电极,利用建立的二维模型,优化了电极中含低曲折因子孔道的多级孔道结构。这些低曲折因子孔道可作为Li+传输的“高速公路”,优化其孔隙率和孔径,可大幅度提升高放电倍率下的能量密度。低曲折因子孔道的最佳孔隙率高度依赖于其孔径,其直径小于10 μm较优。当电极厚度为200 μm且总孔隙率为0.36时,优化后的多级孔电极相比于传统电极,能量密度可提高45.9%~91.4%。此外,当Li+的扩散限制较弱时(例如,电极厚度≤50 μm和总孔隙率≥0.48),优化电极的多级孔结构并不会显著提升电极性能。本工作可为锂电池电极中多级孔道结构的设计提供一定的指导。

关键词: 锂离子电池, 电极, 扩散限制, 多级孔道, 优化

Abstract:

At higher charging and discharging rates, Li+ diffusion in the electrodes of lithium batteries is severely restricted, resulting in a significant decrease in battery performance. To reduce the diffusion limitations, engineering pore structure of electrodes can be an efficient approach. In this work, a LiCoO2 cathode is taken as a model electrode, the hierarchical pore network of the cathode with low-tortuosity pores is engineered with the aid of a two-dimensional model. The low-tortuosity pores act as "highways" for the transport of Li+, and their porosity and diameter are optimized to achieve the maximum energy density at high discharge rates. The optimal porosity of low-tortuosity pores is highly dependent on the diameter of low-tortuosity pores, and a diameter of low-tortuosity pores less than 10 μm is preferable. The preferable hierarchically structured electrode can be 45.9%—91.4% higher in energy density when the electrode thickness is 200 μm and the total porosity is 0.36. Besides, optimizing hierarchically structured electrodes is unnecessary when the diffusion limitation of Li+ is weak (e.g., electrode thickness ≤50 μm and total porosity ≥0.48). This work should provide some guidance to engineer the hierarchical pore network for high-performance Li-ion battery electrodes.

Key words: lithium-ion battery, electrode, diffusion limitation, hierarchical pore network, optimization

中图分类号: