Thin Film Using Micro-Well Patterned Titanium Substrates PrePared by Wet Etching Method

Abstract

Titanium sheet metal substrates used in thin film batteries were wet etched and their surface area was increasedin order to increase the discharge capacity and power density of the batteries. To obtain a homogeneous etching pattern,imately 40m were formed on the surface of the Ti substrate using a photo-etching process with a 20m. 20 m squarepatterned photo mask. All-solid-state thin film cells composed of a Li/Lithium phosphorous oxynitride (Lipon)/LiCoO2system were fabricated onto the wet etched substrate using a physical vapor deposition method and their performanceswere compared with those of the cells on a bare substrate. It was found that the discharge capacity of the cells fabricatedon wet etched Ti substrate increased by ca. 25% compared to that of the cell fabricated on bare one. High discharge ratewas also able to be obtained through the reduction in the internal resistance. However, the cells fabricated on the wetof the thin films, while the cells on the bare substrate demonstrated a good cycling performance.