Development of Laser Structured Silicon-based Anodes for Lithium-ion Batteries

摘要

In order to increase the practical capacity of standard graphite anode and to overcome the drawbacks of pure silicon anode material due to its large volume change, graphite electrodes mixed with silicon nanoparticles are under development. In this work, various types of graphite anodes mixed with 10 wt% silicon nanoparticles were fabricated in view of film thickness and mixing ratio of binder materials. Additionally, free-standing structures were generated on silicon/graphite electrodes by applying ultrafast laser ablation. The mechanical stress within the electrodes can be significantly reduced by means of laser generated artificial porosity. Galvanostatic and cyclic voltammetry measurements reveal that the cells with structured electrodes exhibit excellent electrochemical properties and improved lithium-ion transport kinetic in comparison to cells with unstructured electrodes (reference). Furthermore, cell impedance was investigated by applying electrochemical impedance spectroscopy. Fresh cells with structured electrodes indicate a lower impedance only at full lithiated state. After cycling, these cells exhibit lower impedance at different depth of discharge probably due to a reduced mechanical and chemical degradation compared to reference cells.