As the demands of wearable electronics increase, the development of flexible power sources has become very important to satisfy them. All-solid-state lithium batteries have attracted huge attention over the recent years due to their safe characteristic and wide electrochemical stable window compared to those of liquid electrolyte-based lithium rechargeable batteries, which allows high operating voltage without any worries on safety problems at bending state.However, the cathode thin film, which is a critical component of thin film battery, certainly needs to be crystallized at high temperature because of the hindrance of solid-state lithium diffusion from any imperfections in the crystal. Eventually, the polymer substrate goes through sudden changes because of its poor resistance to high temperature, so a new direction of crystallization should be considered. 

In this work, we present a new fabricating method for all-solid-state flexible lithium batteries using excimer laser annealed cathode thin films, which facilitates fast crystallization of active materials with no damage on substrate. The excimer laser annealed cathode thin films were crystallized without a damage of polyimide substrate. Structural properties of the thin films were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Transmission electron microscopy (TEM). The electrochemical properties were carried out using WBC3000 battery cycler. The initial capacity of developed flexible battery on polyimide substrate was 20 μAh μm^-1 cm^-2 at 0.2 C-rate. It was confirmed that red light-emmitting diode light was turned on continuously during the bending state. We expect that this approach for fabricating flexible batteries will be practically applied for micro-powered flexible electronic devices.