New 'Nuclear Battery' Runs 10 Years, 10 Times More Powerful

[C1ay]

A battery with a lifespan measured in decades is in development at the University of Rochester, as scientists demonstrate a new fabrication method that in its roughest form is already 10 times more efficient than current nuclear batteries - and has the potential to be nearly 200 times more efficient. The details of the technology, already licensed to BetaBatt Inc., appears in today’s issue of Advanced Materials.

 

lefthttp://hypography.com/gallery/files/9/9/8/atomic.jpg[/img]"Our society is placing ever-higher demands for power from all kinds of devices," says Philippe Fauchet, professor of electrical and computer engineering at the University of Rochester and co-author of the research. "For 50 years, people have been investigating converting simple nuclear decay into usable energy, but the yields were always too low. We’ve found a way to make the interaction much more efficient, and we hope these findings will lead to a new kind of battery that can pump out energy for years."

 

The technology is geared toward applications where power is needed in inaccessible places or under extreme conditions. Since the battery should be able to run reliably for more than 10 years without recharge or replacement, it would be perfect for medical devices like pacemakers, implanted defibrillators, or other implanted devices that would otherwise require surgery to replace or repair. Likewise, deep-space probes or deep-sea sensors, which are beyond the reach of repair, also would benefit from such technology.

 

Betavoltaics, the method that the new battery uses, has been around for half a century, but its usefulness was limited due to its low energy yields. The new battery technology makes its successful gains by dramatically increasing the surface area where the current is produced. Instead of attempting to invent new, more reactive materials, Fauchet’s team focused on turning the regular material’s flat surface into a three-dimensional one.

 

Similar to the way solar panels work by catching photons from the sun and turning them into current, the science of betavoltaics uses silicon to capture electrons emitted from a radioactive gas, such as tritium, to form a current. As the electrons strike a special pair of layers called a "p-n junction," a current results. What’s held these batteries back is the fact that so little current is generated - much less than a conventional solar cell. Part of the problem is that as particles in the tritium gas decay, half of them shoot out in a direction that misses the silicon altogether. It’s analogous to the sun’s rays pouring down onto the ground, but most of the rays are emitted from the sun in every direction other than at the Earth. Fauchet decided that to catch more of the radioactive decay, it would be best not to use a flat collecting surface of silicon, but one with deep pits.

 

A layer of silicon riddled with pits, each of which would fill with the radioactive tritium gas, would be like dropping the sun into a deep well lined with solar panels. Almost all of the sun’s rays, no matter which way they were emitted, would strike a well wall. Only those rays that fired straight up and out of the well would be lost. With this reasoning, Fauchet devised a method to excavate pits into a microscopic piece of silicon.

 

The pits, or wells, are only about a micron wide (about four ten-thousandths of an inch), but are more than 40 microns deep. After the wells are "dug" with an etching technique, their insides are coated with a material to form a p-n junction just a tenth of a micron thick, which is the best thickness to induce a current. The Advanced Materials paper details how these wells were dug in a random fashion, yielding a 10-fold increase in current over the conventional design. The team is already working on a technique to create and line the wells in a much more uniform, lattice formation that should increase the energy produced by as much as 160-fold over current technology.

 

"Our ultimate design has roughly 160 times the surface area of the conventional, flat design," says Fauchet. "We expect to be able to get an efficiency that very nearly matches, and we’re doing this using standard semiconductor industry fabrication techniques."

 

Houston-based BetaBatt Inc. has formed to capitalize on the technology, and has recently been awarded a technology commercialization grant by the National Science Foundation (NSF). NSF funded the initial research as well. Collaborators on this research included one of Fauchet’s graduate students, Wei Sun, Nazir Kherani from the University of Toronto, Karl Hirschman from Rochester Institute of Technology, and Larry Gadeken from BetaBatt, Inc.

 

Source: University of Rochester

[BlameTheEx]

A classic case of mistaking an advertising press release for news. The only numbers are in the header, and they are useless.

 

1) What are the actual efficiencies of these new batteries? We can't even begin to consider applications without this information.

 

2) What are the "Current nuclear batteries" that they are comparing them to? Are they referring to the best under development for future NASA missions, the normal standard available off the shelf or what?

 

3) How are they measuring efficiency? Immediate power to weight ratio, total power over lifetime of battery to weight ratio, power to tritium ratio, power to waste heat ratio, power to dollar ratio or what? If power to weight ratio is the measure does the weight include radiation shielding and heat sinks?

 

There is a slightly more detailed press release here:

http://www.rochester.edu/news/show.php?id=2154

 

As best as I read it this 10 times improvement is only in comparison to previous Betavolt batteries. It is careful to point out that those were of limited use. It is NOT a comparison with other more efficient methods of converting radioactive decay to electricity.

 

Sadly nether press release gives a link to the actual paper on the topic (Volume 17 issue 10 of Advanced Materials). As the authors have chosen to publish in a journal that charges a subscription the link would be of limited use to most of us.

 

The commercialisation of these batteries falls to BetaBatt, a company limited to a single web page here: http://www.betabatt.com/

[C1ay]

Well actually, if you follow the link from the bottom of the article where it says Source: University of Rochester and then click on the news release there you'll see that it's exactly the same news release. I also don't agree that the University of Rochester released it for advertising purposes, they released it to show how Philippe Fauchet, professor of electrical and computer engineering at the University of Rochester and co-author of the research, had helped to develop a new method of etching silicon to get a higher yield from betavoltaic cells than those methods that are currently being used. The point of the article was to report that this new method of etching the silicon increased the useful surface area by more than 160 fold over previous betavoltaic batteries resulting in higher efficiencies and lifespans. This will lead to a large increase in the useful lifespan of the spacecraft that use betavoltaics for power as well. Sorry if you find that disappointing.

[BlameTheEx]

Oops. You are right. It is the same news release.

 

Perhaps you are right about Rochester's motives too but that does change the article from being a press release. Not that I am totally against press releases. What I am against is the failure to provide at least links to the necessary basic data. As stands the only way to evaluate this development is to pay a subscription to Advanced Materials. Not even BetaBatt is giving specifications of the batteries it is supposed to market!

 

That betavoltic batteries are improved is news but so what? There are developments all over. The development is only of interest to the extent that it solves problems, or at least gives hope of solving problems. Without the numbers we have no way of telling how likely this is.

 

Of course if betavoltic batteries were already viable then any improvement would be of real interest. You assert "This will lead to a large increase in the useful lifespan of the spacecraft that use betavoltaics for power as well." If betavoltic batteries are already practical for spacecraft then you make a fair point. However I fail to find such an assertion in the article. Correct me if I am wrong but I was under the opinion that the hope is rather that development will one day make betavoltics viable for space. If so we are back to wondering if they will ever compete with alternative solutions, and cursing the lack of numbers.

[C1ay]

You do realize that all research news comes from news releases. To say you are against press releases is to say that you're against research news being published. And then to complain that the author used a venue that would allow them to actually get paid for their work says a lot. Do you work for free? And why do you think data collected from research that investors spent money to produce should be freely available. Are you a contributor? I'm sure that if you have a current development project that this technology might be suitable for, then BetaBatt will gladly send over a sales rep that will overwhelm you with all the data you want at no charge. Give them a call and tell them you're building a space probe or something. You might even get a free sample for your R & D.

 

I did not mean to imply that current spacecraft use betavoltaics, only that those that would could see a large increase in lifespan as a result compared to using current betavoltaics. Poor word choice. If the lifespan of any battery technology can be expanded 10 fold it is a given that any applications that would use that technology would see an increase. One of the design goals of this technology is for it's use in space exploration.

[Pete]

I have access to Advanced Materials through my University.

I don't follow the details in the article (I'm a Business graduate!), and I don't want to post copyrighted material to a public forum, but I'm sending it to BlameTheEx for comment.

[infamous]

That ought to keep the Energizer Bunny hopping.