**8. Conclusion**

In this chapter, the overview of types of thin-film batteries, deposition techniques, mechanisms, fundamentals, advantages and applications of thin-film batteries were given. We summarized the types of thin-film manufacturing technologies, and the choice of any technological pathway will depend on the end-use applications of the thin-film batteries. Physical and chemical methods are used to prepare thin-film batteries. These techniques are used to modify the surface properties of the batteries. In chemical vapor deposition, films are deposited from various chemical reactions to generate the vapor that is deposited on the substrate, while the physical deposition technique involves physical mixing and deposition of the mixture on the substrate without any chemical reaction. The need to address the current energy crisis using the most fascinating next-generation energy storage systems and vast applications of thinfilm batteries has driven research focus on thin-film batteries. Thin-film batteries have a wide area of applications covering the Internet of Things (IoT), implantable medical devices, integrated circuit cards, smart watches, radio-frequency identifier (RFID) tags, remote sensors, smart building control, astronomical mirrors and other wireless devices.
