Nanotube Tangles Power Printable Batteries

George Gruner and his colleagues at the University of California in Los Angeles have created batteries that can be printed onto a surface with nanotube ink. Using the same zinc-carbon chemistry as ordinary non-rechargeable batteries, the flexible batteries are less than one millimeter thick and could power disposable devices such as long-range RFID tags or small displays.

To make the battery, a layer of nanotubes is first deposited in the form of “nanotube ink” onto a surface. This layer acts as the charge collector, which removes current from the battery. Next, a layer of nanotube ink mixed with manganese oxide powder and electrolytes, which carries charge within the cell, is applied on top. This layer acts as the cathode. Finally, a piece of zinc foil – the anode – is applied.

Many carbon nanotubes can be packed into these layers. They form randomly aligned nanotube networks that conduct charge more efficiently than the metals normally used – connecting many points in the battery simultaneously, without hampering the electrochemical process that generates power.

The researchers also made supercapacitors using the inking technique and plan to combine these with batteries for applications requiring more power. Since both printed batteries and supercapacitors can be made entirely at room temperature, it should be possible to mass-produce them using established printing methods, Gruner says.

Gruner says his research team is working to increase power output and to demonstrate suitability of the designs for industrial production.