Companies in the micro-battery industry may use "thin films" to manufacture their devices. The idea is to make a device that is small -- on the scale of semiconductors -- and thereby reduce costs while (hopefully) improving performance.
What are Thin Films?
A thin film is a coating that, by definition, is less than 5 mm. Typically, the advantages advertised over other devices include:
-- they use less material -- their manufacture can usually be automated -- they are usually smaller and more flexible
Many products can be built using thin films, including semiconductors, electronics, photovoltaic parts and a myriad of custom devices. They are generally less expensive and of higher quality than competing technologies.
Research in Thin Film Batteries
One of the leading research labs working on thin film batteries is the US Department of Energy's Oak Ridge National Laboratory (ORNL) in Oak Ridge, Tennessee. In the mid 1990s, they began development of a thin film based lithium battery. To date, they have been awarded 16 patents on this technological endeavor.
Their technology allows for the deposition of a number of films, comprising (mostly) an anode, cathode and electrolyte. The materials are usually sputtered (a process by which thin films are deposited onto a surface -- although other deposition techniques may be used) onto almost any substrate. They are scalable, meaning they can be wired together to provide enough power to be usable for most smaller applications.
The ORNL batteries are about 15 microns thick (by comparison Saran Wrap is about 25 microns thick). The area size determines the power level.
Still, there are some technological issues with the thin film battery and this is why it has not reached its market potential. A number of companies have licensed the technology from ORNL and are attempting to commercialize it. Potential applications (according to ORNL's and others' websites) include miniature transmitters, medical devices, smart cards and MEMs devices.
Advantages of Thin Film Batteries
Thin film battery advantages include a huge number of recharge cycles (ORNL, and some of their licensees, report in the tens of thousands, as do other thin film battery technologies) and economical production for small power requirements. In addition, these batteries tend to be physically flexible; they can be formed to fit in almost any shape, depending on the application.
