For applications that need only small amounts of power, flexible paper batteries look promising by offering a viable alternative to current batteries. These batteries use a paper layer containing the electrolyte as the separator between the anode and the cathode. They are easy and cheap to manufacture because they are produced using printing machines and environmentally friendly because of easy disposal. And as they're thin and flexible, they can be tailored for a large variety of applications, including cosmetics, smart cards, sensors, greeting cards or semi-active RFIDs.
Let's first look at Enfucell, a Finnish start-up and at its technologies.
Enfucell's SoftBattery is "based on traditional paper printing/coating and lamination/heat sealing technology." Below is a picture of this SoftBattery. (Credit: Enfucell)
How does this work? Here is how Enfucell describes its technology.
The paper battery converts chemical energy directly into electricity. In our case, metal is oxidized at one side of paper and manganese oxide or other oxides is reduced at another side of the paper when the battery is connected to applications. The paper-containing electrolyte is used as separator. The metal might be zinc, aluminum, nickel and so on. The process generates electricity without any environmentally harmful by-products and goes on at a very wide temperature and humidity with a stable power output.
Enfucell also details the advantages of such flexible paper batteries which are: "cheap (low manufacturing cost and raw material cost); thin and flexible (customer decides the size and shape); easy disposal due to environmentally friendly technology."
So far, Enfucell has the technology but no real products. The company hopes that its batteries will power wireless devices and applications including cosmetics, smart cards, micro sensors, greeting cards or semi-active RFIDs in one or two years.
This is not the case of an Israeli company named Power Paper, which already is selling a range of products based on a similar technology. It has for example invested in beauty treatments with its PowerCosmetics line of products.
Below are two pictures showing the application of its anti-aging skincare products which use "a novel, micro-electrically driven, user-friendly method to more effectively address consumer desires for a rapid healthy-looking, youthful appearance." On the first one, you can see a woman using the product. (Credit: PowerCosmetics)
And on this second one, you can see the results: reduction of wrinkles and of the appearance of crow's feet. (Credit: PowerCosmetics)
For more information about these skin care products, you can watch a video on PowerCosmetics home page (1 minute and 35 seconds, 15.9 MB) or read this page.
The technologies used by Enfucell and Power Paper are very similar. Here is how Power Paper describes how it works -- with some marketing hype.
Power Paper has developed a breakthrough technology platform that enables the mass production of low-cost, thin and flexible energy cells capable of powering a host of applications. Power Paper's core technology is an innovative process that enables the printing of caseless, thin, flexible and environment-friendly energy cells on a polymer film substrate, by means of a simple mass-printing technology and proprietary inks.
Power Paper cells are composed of two non-toxic, widely-available commodities: zinc and manganese dioxide. The cathode and anode layers are fabricated from proprietary ink-like materials that can be printed onto virtually any substrate, including specialty papers. The cathode and anode are produced as different mixes of ink, so that the combination of the two creates a 1.5-volt battery that is thin and flexible.
So will these paper batteries become common in the years to come? Time will tell.
Finally, I want to thank the alarm:clock team who wrote about Power Paper in "Paper Battery Startup Charges Up First Round Archives" (March 23, 2006).
Sources: Enfucell and Power Paper web sites
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