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April 16, 2008

Media Contacts:

Michael Buckley, The Johns Hopkins University Applied Physics Laboratory
240-228-7536 or 443-778-7536

Kristi Marren, The Johns Hopkins University Applied Physics Laboratory
240-228-6268 or 443-778-6268

The Johns Hopkins University Applied Physics Laboratory
Office of Technology Transfer
Inventions of the Year for 2007

Battery in Nanotubes

Need: There is a need for a new battery with low internal impedance and high capacity, as well as one that discharges over a long period of time relative to conventional batteries. The nanotube battery, according to this case, is such a battery, and may be applied to batteries as structures, sensors, sensor networks, remote controlled toys and vehicles, battery integrated-integrated microprocessors and controllers, and so on.

Technical Description: The generalized element of the nanotube battery includes a polymer or silicon matrix base that is 10-20 µm thick, to which is fixed nanotubes having a length of 2-15 µm, an inner diameter of 10 nm to 4 µm, and an outer diameter of 20 nm to 5 µm. The nanotubes may be made from metals and/or metal oxides such as nickel, copper, tantalum, gold, titanium oxide, etc. A conducting layer is deposited on the matrix and in contact with exteriors of the nanotubes, but it is applied so that the interiors of the nanotubes remain open (i.e., free of the conducting layer so as to be accessible to being filled with chemicals). The conducting layer may be connected so as to form a cathode or anode electrode. The nanotubes are filled with energy-storing and energy-discharging chemicals such as oxides and hydroxides of nickel, cadmium, silver, zinc, and lithium (and compositions thereof). The energy-storing and energy-discharging chemicals fill 50-80% of the volume of each of the nanotubes.

The structure generalized above, which may serve as either an anode or cathode battery layer, is repeated in anode and cathode layers to form a battery. That is, the battery includes (i) a cathode layer, including a cathode matrix, nanotubes fixed thereto filled with a cathode chemical, and a conducting layer thereon, and (ii) an anode layer, including an anode matrix, nanotubes fixed thereto filled with an anode chemical, and a conducting layer thereon. The cathode and anode layers are attached, so that their respective conducting layers do not touch, to form a battery cell. Stacking layers upon layers builds up a battery of desired thickness and voltage.

Images of the technology are shown in Figure 1.

Stage of Development: Preliminarily reduced to practice, but not tested extensively

Figure 1.
(a) Ni nanotubes arranged in situ in a 10-µm-thick polymer matrix. (b) A magnified view of an Ni nanotube after etching the polymer away. (c) Initial stages of filling the nanotubes with an energy-storing/energy-discharging chemical. (d) Layering a cathode and an anode matrix on each other to form one cell, with the electrolyte in between and conducting gold coatings on the outside surfaces. (e) Layering two (or more) cells to form a battery.

The Applied Physics Laboratory, a division of The Johns Hopkins University, meets critical national challenges through the innovative application of science and technology. For information, visit www.jhuapl.edu.