Structure and Performance of Through-holed Electrodes Prepared with a Pico-second Pulsed Laser for Lithium-Ion Battery

Abstract

This study analyzed holed structures formed in lithium iron phosphate（LiFePO₄; LFP）cathodes and graphite anodes with a picosecond pulsed laser, which can remarkably improve the material’s high-rate performance. The holes in the structure have tapered shapes. During hole formation in the LFP cathode layer, a minute amount of LFP was transformed to Fe₂O₃ through LFP oxidation by laser irradiation. Additionally, results demonstrated that percussion drilling by the laser beam increased the LFP cathode layer porosity because the strong effect of the laser on the LFP layer evaporated the Al current collectors. After laser ablation, Al deposits formed on the hole sidewalls because of the cooling Al vapors. The increased LFP layer porosity increases the permeation of Li^＋-containing electrolyte solutions into LFP layers. The three-dimensional（3D）electron pathway formed by the Al deposits on the sidewalls of holes and the Al current collector plane were regarded as improving its high-rate performance.