Facile fabrication of patterned Si film electrodes containing trench-structured Cu current collectors for thin-film batteries

•Trench-structured Cu current collector was fabricated using facile method.•Wholly covered Si film electrode exhibited an increase in capacity.•Selectively covered Si film electrode exhibited good efficiency and cycleability. In this study, two types of patterned (wholly and selectively covered) Si film electrodes containing trench-structured Cu current collectors are proposed for use in thin-film Li-ion batteries. The proposed electrodes are fabricated using a standard laser printer and electrochemical etching. The formation of the trench structure in the Si film electrodes results in improved electrochemical performance compared to conventional continuous Si film electrodes. The wholly covered Si film (WCS) electrode exhibits an 18.5% increase in capacity compared to the continuous Si film electrode. The selectively covered Si film (SCS) electrode, which is covered by Si film only at the bottom of the trenches, exhibits better electrochemical performance than the WCS electrode. An SCS electrode with a trench width of 45μm and trench height of 14.3μm exhibits the best electrochemical properties in terms of efficiency (85% in the first cycle) and cycle performance (60% capacity retention after 100 cycles).