Si film electrodes with surface-modified Cu current collectors for micro Li batteries

Abstract

Si film electrodes were fabricated onsurface-modified Cu current collectors using an oxidation-reduction process. Flower-like nanostructures (FLNSs) with diameters of 2-3 mu m and plate-like nanostructures (PLNSs) with lengths of 1 m were formed on the Cu foil oxidized at 423 K for 0.5 h, but only the PLNSs remained after sonication. Reduction of the preoxidized Cu foil at 673 K resulted in the formation of platelike and coral -like nanostructures on the Cu foils reduced for 1 and 3 h and a smooth surface without specific structures on the Cu foil reduced for 6 h. The best electrochemical properties in terms of the first columbic efficiency (85.4%) and the cycle performance (67.3% at 50 cycles) were obtained from the Si film electrode fabricated on the Cu foil that had been reduced for 3 h because the coral -like nanostructures on the Cu foil enhanced the adhesion of the Si film and improved the structural stability of the Si film electrode during the electrochemical reactions. (C) 2016 Elsevier Ltd: All rights reserved.