Pulse Electrodeposition of Interconnected Porous Si-Cu Composites as Anodes for Lithium-Ion Batteries

Abstract

Si-Cu composites composed of an alternate Si-rich layer and Cu layer were obtained by two-potential pulse electrodeposition of −1900 mV and −1600 mV in 0.002 mol l−1 Cu(TfO)2−1 mol l−1 SiCl4(saturated)-[BMP]Tf2N ionic liquid at room temperature. The potential lasting time ratios for −1900 mV and −1600 mV changed from 0.5 s/0.5 s to 4 s/0.5 s, respectively. All the Si-Cu composites showed an interconnected porous structure caused by the SiCl4 bubbles templates formation during electrodeposition. Especially, the Si-Cu 4–1 composite prepared at −1900 mV/−1600 mV for 2 s/0.5 s within 1 h, presented an interconnected mesoporous and macropore structure. And the Si-Cu 4–1 composite exhibited the best rate and cycle performances as anode of lithium-ion battery, with the initial capacity of 1589.2 mAh g−1 and capacity retention ratio of 72.6% after 1000 cycles at 1 C. This is attributed to the lowest charge transfer resistance and fastest Li+ transfer ability due to the beneficial porosity-structure. This finding provides a new idea for the directly designing of interconnected porous material by pulse electrodeposition.