For a long time, batteries were bulky and heavy. Now, a new cutting-edge battery is revolutionizing the field. It is thinner than a millimeter, lighter than a gram, and can be produced cost-effectively through a printing process.

Printable batteries

In the past, it was necessary to race to the bank for every money transfer and every bank statement. Today, bank transactions can be easily carried out at home. Now where is that piece of paper again with the TAN numbers? In the future you can spare yourself the search for the number. Simply touch your EC card and a small integrated display shows the TAN number to be used. Just type in the number and off you go. This is made possible by a printable battery that can be produced cost-effectively on a large scale.

It was developed by a research team led by Prof. Dr. Reinhard Baumann of the Fraunhofer Research Institution for Electronic Nano Systems ENAS in Chemnitz together with colleagues from TU Chemnitz and Menippos GmbH. “Our goal is to be able to mass produce the batteries at a price of single digit cent range each,” states Dr. Andreas Willert, group manager at ENAS.

The characteristics of the battery differ significantly from those of conventional batteries. The printable version weighs less than one gram on the scales, is not even one millimeter thick and can therefore be integrated into bank cards, for example. The battery contains no mercury and is in this respect environmentally friendly. Its voltage is 1.5 V, which lies within the normal range. By placing several batteries in a row, voltages of 3 V, 4.5 V and 6 V can also be achieved. The new type of battery is composed of different layers: a zinc anode and a manganese cathode, among others. Zinc and manganese react with one another and produce electricity. However, the anode and the cathode layer dissipate gradually during this chemical process. Therefore, the battery is suitable for applications which have a limited life span or a limited power requirement, for instance greeting cards.

The batteries are printed using a silk-screen printing method similar to that used for t-shirts and signs. A kind of rubber lip presses the printing paste through a screen onto the substrate. A template covers the areas that are not to be printed on. Through this process it is possible to apply comparatively large quantities of printing paste, and the individual layers are slightly thicker than a hair. The researchers have already produced the batteries on a laboratory scale. At the end of this year, the first products could possibly be finished.

In revisiting a chemical reaction that’s been in the literature for several decades and adding a new wrinkle of their own, researchers with Berkeley Lab and the University of California (UC) Berkeley have discovered a mild and relatively inexpensive procedure for removing oxygen from biomass. This procedure, if it can be effectively industrialized, could allow many of today’s petrochemical products, including plastics, to instead be made from biomass.

“We’ve found and optimized a selective, one-pot deoxygenation technique based on a formic acid treatment,” said Robert Bergman, a co-principal investigator on this project who holds a joint appointment with Berkeley Lab’s Chemical Sciences Division and the UC Berkeley Chemistry Department.

The formic acid, Bergman said, converts glycerol, a major and unwanted by-product in the manufacturing of biodiesel, into allyl alcohol, which is used as a starting material in the manufacturing of polymers, drugs, organic compounds, herbicides, pesticides and other chemical products. Allyl alcohol today is produced from the oxidation of petroleum.

Said Jonathan Ellman, a UC Berkeley chemistry professor and the other principal investigator in this research, “Right now, about five percent of the world’s supply of petroleum is used to make feedstocks that are synthesized into commodity chemicals. If these feedstocks can instead be made from biomass they become renewable and their production will no longer be a detriment to the environment.”

Biomass has been drawing wide public attention for its potential to be converted into carbon-neutral biofuels, but there is also huge potential for it to be converted into   chemical feedstocks. It is safe to say that a day does not go by without each of us making use of multiple petrochemical products. Feedstocks for such products obtained from biomass rather than petroleum would be renewable as well as biodegradable. However, unlike petrochemical feedstocks, which are made by adding oxygen to petroleum, biomass feedstocks require the removal of oxygen from the raw material.

Bergman and Ellman, working with Elena Arceo, a Fulbright scholar from Spain, and Peter Marsden, a UC Berkely graduate student, used labeling experiments and a unique distillation system to take a new look at an old chemical reaction in which formic acid, the chemical found in bee venom, was used to remove oxygen from glycerol. In its original conception, the reaction was low-yielding, primarily because of substantial charring, an unselective  combustion that leads to an intractable mixture under high heat. Bergman and Ellman found that simply protecting this reaction from air provided a much improved process for the deoxygenation of glycerol.

Said Bergman, “Treating glycerol with formic acid while directing a stream of nitrogen through the reaction mixture completely eliminates charring. Besides protecting the product from atmospheric oxidation, the nitrogen also facilitates distillation of the alcohol. The final product shows substantially improved yield (80-percent) and higher selectivity.”

Said Ellman, “From our studies we also gained a much better understanding of the basic chemistry behind the reaction. We thought that the charring was a random oxidation process because the reaction had been carried out in air and we expected that running it in a nitrogen environment would improve things. However, in studying the basic chemistry we uncovered an unexpected reaction pathway that really broadens the generality of this reaction and expands its potential applications.”

With this new reaction pathway, the formic acid-mediated deoxygenation technique developed by Bergman and Ellman could be used to convert the carbohydrates in biomass, as well as other polyhdroxy compounds, into the chemical feedstocks, such as olefins (alkenes) that are now derived from petroleum. The technique could also prove useful in the process by which biomass is converted into liquid transportation fuels.

Said Bergman, “Our preliminary results with inexpensive biomass-derived polyols suggest that the reaction of polyhydroxy compounds with formic acid will be a valuable alternative for the manufacture of reduced oxygen content products. However, scaling this technique up so that biomass feedstocks are competitive with feedstocks derived from petroleum is going to be an engineering challenge.”

Added Ellman, “Scaling the technique up to industrial levels is probably going to require the combined efforts of industrial and academic laboratories, but if we are able to one day make commodity chemicals as well as fuels from biomass, we can protect the atmosphere from further damage and at the same time help lower current carbon dioxide levels.”

Berkeley Lab is a U.S. Department of Energy national laboratory located in Berkeley, California.  It conducts unclassified scientific research and is managed by the University of California.