Polymer‐free Vertical Transfer of Silicon Nanowires and their Application to Energy Storage

• DOI: 10.1002/cssc.201300202
• Publication Date: 2013-09-12T17:34:29Z
• Authors: Han‐Jung Kim; Jihye Lee; Sang Eon Lee; Wanjung Kim; Hwan Jin Kim; Dae‐Geun Choi; Jong Hyeok Park
• Keywords: Silicon; Electric Power Supplies; Nanowires; Electric Conductivity; 02 engineering and technology; Lithium; 0210 nano-technology; Electrodes; 7. Clean energy

AbstractSilicon nanowires (SiNWs) for use as lithium‐ion battery (LIB) anode materials have been studied for their one‐dimensional (1D) properties and ability to accommodate large volume changes and avoid rapid capacity fading during cycling. Although the vertical transfer of SiNWs from their original substrate onto a conducting electrode is very important, to date, there has been no report of a direct integration method without polymer binders. Here, we propose for the first time a vertical transfer method for SiNWs grown on a Si substrate directly to the current‐collecting electrode without using a polymer adhesive for the use as a binder‐free LIB anode. The vertical SiNWs produced using a low‐cost wafer‐scale metal‐assisted chemical etching (MaCE) process have been successfully transferred directly to a copper electrode coated with a thin Ag layer by using a simple hot pressing method. When evaluated as an LIB anode without using conventional polymeric binder and a conducting additive, the transferred vertically aligned SiNWs showed a high specific capacity (≈2150 mAh g−1) and excellent rate performance. It is believed that the anode‐manufacturing process is simple and fast, thus enabling a large‐scale production that is of low‐cost, broadly applicable, and provides new avenues for the rational engineering of Si‐based electrode materials with enhanced power density and conductivity.