3D silicon/graphite composite electrodes for high-energy lithium-ion batteries

Graphite composite electrodes mixed with silicon are proposed as next generation anode material for high energy and high power applications. In order to overcome drawbacks caused by volume changes of silicon particles during electrochemical cycling and to maintain high specific capacities at enhanced C-rates, free-standing structures are generated on silicon/graphite electrodes by applying ultrafast laser ablation. Electrochemical properties are systematically investigated by means of galvanostatic measurements, cyclic voltammetry, and electrochemical impedance spectroscopy. Cells with structured electrodes exhibit improved battery performances and lithium-ion transport kinetics in comparison to cells with unstructured electrodes. Furthermore, the cells with structured electrodes exhibit a lower impedance at fully lithiated state. After cycling, post-mortem analysis is performed revealing that the mechanical stress within the electrodes and current collector can be significantly reduced due to laser generated free-standing structures.