Scientists have found a way to make batteries from paper and spit. But don’t expect the batteries to power your electric vehicle or take the place of your lithium-ion home storage system. 

Instead, the biodegradable, paper-based batteries devised by a team at Binghamton State University of New York are designed for disposable, one-time applications “like AA batteries,” said one of the researchers.

“I would not compare it to traditional batteries because the application is different,” said associate professor Seokheun "Sean" Choi from Binghamton’s Electrical and Computer Engineering Department. “Ours will be for low-cost, low-power applications like biosensors.”

In a paper published June in the journal Advanced Sustainable Systems, the research team noted that paper-based microbial batteries “may be an excellent way to reduce the dramatic increase in electronic waste.”  

Until now, though, progress in the development of paper batteries has been hampered by their low performance and questionable biodegradability.

The Binghamton battery team’s concept uses polyamic acid and polypyromellitic dianhydride‐p‐phenylenediamine in a porous hydrophilic network of cellulose fibers. 

According to earlier research, microbial fuel cells in the battery can be activated by water, such as that contained in saliva. The technology has a much higher power‐to‐cost ratio than previously reported paper‐based microbial batteries, the researchers claimed.

And the biobattery biodegrades without special facilities, conditions or other microorganisms, they said. Choi said his team’s battery was capable of producing up to 4 microwatts of power and 26 microamps of electric current per square centimeter.

A rough calculation shows that to store or deliver the peak output of a typical 6-kilowatt residential solar array, you would need around 150,000 square meters of such a paper battery. If laid out as a square, this would have sides around 387 meters long. 

In theory, it might be possible to cut this down to a more manageable size, under 2.3 square meters, by folding the paper eight times, which is about the practical limit for the number of times you can fold the material. 

Nevertheless, it is clear that paper-based batteries will not pose a threat to lithium-ion any time soon. “This is for small-power applications, like HIV biosensors, which need to be disposed [of] right after use,” Choi confirmed. 

While paper batteries may be some way off commercialization and are unlikely to ever compete with mainstream technologies such as lithium-ion, they could be useful to the wider energy storage market in two ways.

One is that they could extend the range of devices that are able to store energy, potentially improving the flexibility of the electricity network. Last year, a paper on grid regulation in the U.K. recommended that storage should be embedded right across the energy system.

Paper batteries could potentially extend this storage capacity down to very small and transient sources of electrical demand, for example avoiding the need for plug-in sensors in some medical applications.

By doing this, cheap and biodegradable paper batteries could provide a second benefit: helping relieve the materials burden imposed by increasing electrification.

Although it is still unclear how the transition from a fossil-fuel to a renewables-and-storage system might stress supplies of materials such as cobalt, there can be little doubt that making some batteries from paper could ease the situation.

The next unknown: How much will biobatteries cost?

A matchbook-sized, paper-based biosensor developed by Choi and his colleagues in 2015 was cited as costing five cents. Today, the paper battery concept is still at “a science level,” said Choi, with testing needed to establish basic characteristics such as bacterial toxicity, packaging, storage and shelf life.

The work is being supported by a grant from the National Science Foundation and carried out within the Center for Research in Advanced Sensing Technologies and Environmental Sustainability at Binghamton. 

Separate from the work at Binghamton, in July a Swedish packaging company called BillerudKorsnäs announced it was working with Uppsala University in Sweden on the development of paper batteries to help with package tracing.

“With electrodes based on cellulose from wood fiber, the ambition is that in the future it will be possible to recycle batteries along with their boxes and make them into new boxes or paper batteries,” said the company.