The Technograph

Imagine trying to complete last minute class work that requires a calculator. All of a sudden, your calculator runs out of power, and you have no back up batteries. By the time you run to a nearby store, your assignment will be past due; this assignment would have raised your grade. You can’t ask your roommate for help because they’re out at Clybourne’s. What do you do?

Instead of doing calculations by hand on paper, why not make batteries out of paper? Researchers at Rensselaer Polytechnic Institute have created an efficient battery (later further tested by Stanford University researchers), which is made of paper and runs on ink soaked in carbon nanotubes and silver nanowires. The paper is made up of many tiny, interconnected fibers which can easily connect carbon nanotubes.

The size of the battery is also an important factor in the design. The small diameter helps the ink's carbon nanotubes and silver nanowires stick strongly to the paper, and this makes the battery very durable. In fact, the paper battery, which can also work as a supercapacitor, can last through 40,000 charge-discharge cycles, an amount that is in fact more than lithium batteries. The strong energy comes from the design of the battery: it is designed as an integrated device which doesn't involve multiple processes of transferring energy in order to get the battery to work. A single battery has many separate components that involve lots of energy transfer, thus making it use more power than necessary. The materials in the ink make ideal conductors because they can move electricity more efficiently than ordinary solutions. Professor Linhardt, creator of the paper battery at Rensselaer Polytechnic Institute, explains that increasing power is also possible. “If we stack 500 sheets together in a ream, that’s 500 times the voltage. If we rip the paper in half, we cut the power by 50%. So we can control the power and voltage issue.”

The battery works in a way that is consistent with the design. Normally, a chemical reaction between an electrolyte and metal produces electrons, which makes the energy flow from the negative to the positive end. However, the paper battery undergoes a chemical reaction between the electrolyte and the carbon nanotubes to produce electrons. The electrons meet at the negative end of the battery and then flow along a connected wire to the positive end. The electron flow from the negative end to the positive end is required for the chemical reaction to continue.

The paper battery has a bright future. It is now being considered as a source of power for smartphones; it’s small size and strong power makes the paper battery an efficient choice. Another related project that Linhardt is working on involves pacemakers. The paper battery would use electrolytes in human blood to power the pacemakers. The materials are not toxic because they are biodegradable. Furthermore, a main goal of Linhardt is to create paper batteries large enough to power a vehicle, such as a car. Researchers at Stanford University are starting to make batteries out of textiles, as well. However, carbon nanotubes are very expensive, which may affect the outcomes of these projects.

Tagged with: paper, batteries, battery, nanotubes