Silicon-based 3D electrodes for high power lithium-ion battery

Abstract

The well-known drawbacks of silicon-based anode materials are the huge volume change resulting in film cracking, film delamination and pulverization of the active material. In order to reduce mechanical stress and to improve film adhesion, free-standing structures and modified current collector surfaces were generated by applying ultrafast laser processing. Freestanding structures were generated on pure silicon and silicon-doped graphite electrodes. Specific capacities were measured by galvanostatic cycling as function of C-rate. It could be shown that free-standing structures can compensate the volume changes which occur during electrochemical cycling. The capacity retention at high C-rates (> 0.5 C) was significantly improved. Moreover, laser-induced micro/nano-surface patterning was realized on copper current collectors, prior to deposition of pure silicon. Improvement of specific capacity could be achieved during electrochemical priming. The impact of 3D electrode architectures regarding cycle stability, capacity retention and cell lifetime will be discussed in detail.