Finite element modeling of stress and adhesion in laser-textured electrodes for enhanced lithium-ion battery performance

Volumetric expansion and contraction during Li-ion battery cycling is known to contribute to capacity fade and aging due to mechanical stress within the active material and current collector of electrodes. In the present work, a finite element model (FEM) is employed to investigate the effects of nanosecond pulsed laser texturing of current collectors on the stress distribution at the interface between the active material and current collector of LiFePO4\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_4$$\end{document} (LFP) cathodes and graphite anodes. Peel-off tests, single-lap shear tests, and volumetric changes due to lithiation and delithiation are modeled separately for electrodes with and without laser-textured current collectors to determine the effects of laser processing on the resulting deformation, total contact stress, and Von Mises equivalent stress. Crater geometry is based on the experimentally acquired surface topography of aluminum and copper current collectors subject to nanosecond pulsed laser irradiation. Texturing of current collectors is found to be beneficial to surface adhesion by increasing the effective contact area and reducing the Von Mises equivalent stress at the interface, thus reducing the risk of electrode damage and delamination during battery cycling. The results provide a physical explanation for experimentally observed increases in adhesion between the active material and current collector following laser texturing, with simulation outcomes suggesting that moderate laser power should be employed to maximize adhesion with the active material while limiting material removal and heat accumulation.