(Invited) Electrodeposition As a Versatile Method to Prepare Materials for the Storage and Conversion of Sustainable Energy

Abstract

Sustainable energy carriers such as sun light, wind or biomass will play a crucial role in our future. After converting the energy, one should be able to store it and transport it to places where it is needed most. Therefore, the research on materials for storage systems, such as batteries, supercapacitors and fuel cells is an important aspect. Electrodeposition is a powerful technique for the preparation of such materials. As industry strives to produce smaller portable devices, one needs also smaller and lighter batteries with a high storage capacity per gram of active material. The commercial graphite anodes are limited to ca. 370 mAh/g, but silicon and C-Si composites have a theoretical storage capacity beyond 1000 mAh/g. Thus, nanostructured Si, such as nanoporous Si layers, ordered arrays of Si (porous) nanopillars produced by using a combination of nanoimprint lithography and metal-assisted chemical etching or silicon thin films deposited from ionic liquids could be used as high-capacity anodes in Li-ions batteries. Another interesting semiconductor material besides Si is Cu2O. Photo-cathodes from Cu2O can be used to produce hydrogen as a chemical fuel by utilizing direct solar energy and its narrow bandgap of 2.0-2.2 eV that can lead to the theoretical value of solar-to-hydrogen efficiency of 18 %. One can fabricate Cu/Cu2O porous electrodes using the hydrogen bubbles as a dynamic and effective template by electrochemical deposition. These foam electrodes can then be used as photocathodes for water electrolysis under visible light irradiation. This contribution will discuss recent results from the authors’ labs on developing new anode materials for Li-ion batteries (Si based), new electrodes for electrochemical water splitting (Cu2O based) and for electrocatalysis. Further, approaches using light induced plating for electrical front side contacts of solar cells will be presented.