Ultra-dense and highly doped SiNWs for micro-supercapacitors electrodes

•Growing silicon nanowires in porous alumina enables to increase their density.•Electrode capacitance is increased thanks to the SiNWs growth in alumina template.•SiNWs/SiNWs micro-supercapacitors have a promising stability in ionic liquid.

The use of nanoporous anodic alumina as a template for silicon nanowire growth enables the production of ultra dense nanowire arrays with density up to 8.109 cm−2. The integration of such nanowire arrays in micro-supercapacitor electrodes significantly improves the electrode capacitance per planar surface area and nanowires length unit compared to electrodes made from silicon nanowires grown from gold colloids (from 5.2 μF.cm−2.μm to 36.7 μF.cm−2.μm). Micro-supercapacitors with such electrodes and ionic liquid as electrolyte have a very promising cycling stability featuring less than 1% of losses after 300 000 cycles.