Microfabricated thin-film batteries : technology and potential applications

Abstract

High-energy-density lithium ion batteries have enabled a myriad of small consumer-electronics applications. Batteries for these applications most often employ a liquid electrolyte system. However, liquid electrolytes do not allow for small scale and thin-film production as they require hermetic sealing. The aim for batteries in any size or shape, without the restrictions liquid components pose, has led to the development of solid electrolyte systems. ll-solid-state thin-film batteries add a new dimension to the space of battery applications. The purpose of this thesis is to assess the application potential for solid-state thin-film batteries, particularly with regard to CMOS integration. Such batteries were developed with the aim of creating a power unit on a silicon microchip. The various degrees of integration of thin-film batteries on a silicon wafer are examined. All of them show limitations that make fabrication of batteries on a wafer not viable at present from a business standpoint. A search for other commercializable applications for thin-film batteries leads to solid-state bulk batteries made from thin-film batteries. The underlying technology here as well as the market situation and a potential business model are discussed.