Nano Scale Development May Yield Macro Results for Robots

We keep struggling to build bigger, more powerful and more useful robots, but invariably battery capacity and life turn out to be major roadblocks. Practical robot applications require a level of autonomy and independence, which means that they have to carry their operating power along with them and can't be constantly traveling back to a charging station to refuel.

Even at the hobby robot level batteries have been a major obstacle. A Kondo KHR-2HV or a Hitec Robonova-1 typically operate for considerably less than 30 minutes before their batteries need to be replaced or recharged. Of course the same problem is prevalent among other consumer electronic devices like cell phones, laptop computers, and mp3 players.

Thankfully, because of advanced nano-wire research conducted at Stanford University. all that may soon change. Operating times could be expanded by up to 10 times as long. Laptops could run on batteries for several days, and humanoid robots could go for 4 to 6 hours at a stretch.

In a research paper titled "High-performance Lithium Battery Anodes Using Silicon Nanowires" published on the Nature Nanotechnology website, Yi Cui, an assistant professor of materials science and engineering, laid out the background on this exciting new technological advance.

According to the paper, traditional lithium battery anode designs have steered away from the use of silicon in favor of graphite or other nitride and oxide materials. Theoretically, silicon would be the most effective choice based in its low discharge potential and the fact that it has the highest charge capacity -  more than an order of magnitude higher than alternative material choices.

The major problem has been that the silicon's volume changes as lithium is inserted and extracted in operation. The volume increase can be up to 400% and often results in breakdown of the structure and diminished storage capacity.

By using SI nano-wires, the Stanford research project was able to create and successfully test, lithium battery electrodes that minimize degradation and lowering storage capacity. Rather than a rigid and prone to fracturing structure, the nano-wires provide the flexibility and expandability critical for the application.

Also since they are connected, both physically and electrically, to the battery current collectors, the nano-wires actually increase the available contact surface area and increase overall efficiency.

The team believes that their research can be quickly put into actual application in a fairly short period of time since the underlying processes are already well understood by the battery industry.


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