Forgot your password?
Power Portables Hardware

Nanotech Anode Promises 10X Battery Life 193

Posted by kdawson
from the all-day-laptop dept.
UNIMurph sends word out of Stanford University that researchers have discovered a way to increase battery life tenfold by using silicon nanowires. Quoting 'It's not a small improvement,' [lead researcher Yi] Cui said. 'It's a revolutionary development.' Citing a research paper they wrote, published in Nature Nanotechnology, Cui said the increased battery capacity was made possible though a new type of anode that utilizes silicon nanowires. Traditional lithium ion batteries use graphite as the anode. This limits the amount of lithium — which holds the charge — that can be held in the anode, and it therefore limits battery life... 'We are working on scaling up and evaluating the cost of our technology,' Cui said. 'There are no roadblocks for either of these.'"
This discussion has been archived. No new comments can be posted.

Nanotech Anode Promises 10X Battery Life

Comments Filter:
  • Good deal (Score:3, Interesting)

    by alshithead (981606) on Wednesday January 16, 2008 @01:30AM (#22062952)
    Now, if we can see the same kind of improvements in electricity transmission, solar power electricity generation, and larger scale electricity storage, we might be able to really reduce fossil based fuels and CO2 emissions.
  • Re:Good deal (Score:5, Interesting)

    by Rei (128717) on Wednesday January 16, 2008 @02:37AM (#22063312) Homepage
    Since when does "what we have now" imply "what we'll have with the radical technology improvements that are presently occurring"? You do realize that not only are solar thermal prices dropping, but there have been some *major* advancements in the economics of photovoltaic systems. Silicon cells are typically profitable to sell at $4/W (and are currently selling at $5/W because of supply shortages). CIGS cells are profitable at $1/W. This is a major, major leap that'd make solar cheaper than coal almost everywhere in the world.

    Let's look at Nanosolar as an example. Their first plant, when at full capacity, will make them one of the biggest solar producers in the world (430 MW/year if I recall correctly). But this is just their first plant. Selling cells that are profitable at $1/W at nearly $5/W means they'll be profiting hand over fist, which means that investors will fight for the chance to throw money at them. How long do you think it'll take them to scale up with essentially unlimited venture capital? I'm betting not very long. They built their current facility with $100M raised just a year and a half ago, and they've already delivered their first product. Given that most of that money had to go toward simply commercializing their laboratory-scale process, what sort of capacity do you think they could pull off with, say, the next $1B in cash? Dozens of GW/year? And Nanosolar is just one CIGS manufacturer among many. And there's CdTe, too. Unmet demand begs for a market solution. It's inevitable that it's going to be filled.

    Longer term, here's a crazy new tech for you to chew on: nanoantenna solar cells []. A completely different process than conventional cells, which use photons to knock electrons off a donor, these new cells are simply designed to receive solar energy in the same way that a larger antenna receives the several-orders-of-magnitude-longer wave radio signals. They should be able to be produced on a cheap reel-to-reel process like CIGS cells, yet they have the potential to be as much as 80% efficient, even receiving the infrared that the Earth emits at night.
  • by BlueParrot (965239) on Wednesday January 16, 2008 @02:45AM (#22063378)
    Very briefly put, no. The explosive nature of lithium batteries has very little to do with the electric energy stored in them. If the electric energy stored in a battery was even remotely close to the amount of energy released by burning the chemicals they are composed of, then we would all be driving electric cars by now. In fact, more modern lithium batteries are less prone to explode because they have lower internal resistance, so they don't heat up as much when discharged. I keep seeing this fallacy about energy content vs explosive danger when people discuss batteries, but it is frankly nonsense. Many high-power explosives don't produce a whole lot of heat when they detonate, it is the rapid shock-wave that gives them their destructive power. Conversely, regular butter contains enough energy to drive your car on it, but it is quite tricky to ignite and hence fairly safe.

    Anyway, poorly manufactured Lithium batteries are dangerous because they ignite easily. It has very little to do with their energy content.
  • Re:Dupe (Score:5, Interesting)

    by Rei (128717) on Wednesday January 16, 2008 @02:54AM (#22063424) Homepage
    And, let me add, I don't say this to diminish the importance of this news. A severalfold improvement is major, major news. Not in the least because this anode likely lends itself to very rapid charging at the same time. What we're looking at is, as it stands, giving it the sort of charge time and range as a gasoline vehicle, meaning that there's no reason to stick with gasoline (when you can get lower maintenance (assuming long lifespan batteries), higher torque, quieter, more thermodynamically efficient vehicles that only require gas station visits on long trips, require hardly any new infrastructure (versus oil, which needs a lot of infrastructure construction) due to mostly off-peak charging (timer-based to get you a low rate and use our huge amount of unused off-peak capacity), lets us use domestic energy supplies instead of funding our enemies with oil imports, and even if all of the electricity came from burning fossil fuels, would still emit almost half the greenhouse gasses. An equivalent cathode improvement for electric vehicles simply means that you could then drive cross-country on a single charge.

    As for lifespan, Yi Cui's team expects to be able to get at least 1,000 cycles out of this. That may not sound like much, but when you can go ~350 miles on a charge, that's 350,000 miles. And not like the battery just disintegrates up at the end of its lifespan; it simply doesn't hold as much charge.
  • Re:Good deal (Score:3, Interesting)

    by Eivind (15695) <> on Wednesday January 16, 2008 @03:50AM (#22063732) Homepage
    As these things go though, "doubling every 5 years" is not ambitious at all, infact that is very VERY conservative and much less than the increase in production of PV currently taking place. It is, afterall, less than 15% of growth a year.

    The IEA PV trends report from 2003 estimated 20% growth a year for the next decade, but has since been revised upwards. Current trend is looking more like 25% growth in area produced year, which gives somewhat more than that in power generated because average efficiencies are climbing (allbeit slowly).

    Furthermore, increased awareness and interest in global warming is likely to lead to increased incentives and consumer-interest, so I personally think the trend is more likely to grow rather than stall. My guess would be 30% growth a year for the next decade, which is aproximately double your estimate. This is also ignoring HEAT from the sun, which is currently at about half a percent of our energy-needs and *also* growing rapidly.

    Still, you're right: Neither solar nor any other renewable can singlehandedly solve the problem in the next 20 years timeframe. They can contribute, particularily when many and diverse ones are used, but they can't alone solve the problem.

    Proven tech can do a lot though. Did you know that if USA where as efficient measured in GDP/Energy-consumed as Sweden is, you'd be consuming -half- the energy you currently do ? That's not rocket science, that's what Sweden does -TODAY- (and Sweden is improving too!)

    We're going to need more than -one- answer; if it was easy, it woulda been done a long time ago.
  • by giorgist (1208992) on Wednesday January 16, 2008 @03:53AM (#22063748)
    Hey hey lighten up. This is news for nerds. If you want to read about things that are on the market, go read ebay. It does get frustrating, but be critical and enjoy NEWS. Things are not simply evolutionary, things are changing increadably fast on the big picture. Step back and look just a couple of ago. The difference is evident. Each technology/science front is moving forward pretty fast. And all together are starting to tie in ... look at MEMS ... 2GB USB sticks for a couple of bucks, all the music and human knowlege in your pocket, supercomputing/navigating phones, genome Vs History. All this comes to you care of Slashdot ... plus ponies ... pink ones ... what more do you want G
  • by mcrbids (148650) on Wednesday January 16, 2008 @04:24AM (#22063904) Journal
    It's 2008. We still don't have flying cars, practical nuclear fusion, fission-powered cars, or multi-petabyte holographic storage devices. In the real world, advances in technology are usually incremental and evolutionary in nature, or a serious tradeoff at best (As an example, the move underway from platter-based hard drives to solid-state hard drives, while revolutionary in nature, involves massive tradeoffs in price-per-gigabyte which are only slowly lessening). It took CD technology a decade or two to give way to a successor with 10 times the storage capacity (dual-layer DVD-R), and making bits smaller is (arguably) a lot easier than increasing energy density (barring the use of nuclear technology or other exotic things which-- again-- isn't realistically going to happen any time soon).

    Flying cars don't need flying drivers, they need driving pilots. There are about 650,000 pilots in the United States with a certificate of Private Pilot or better. (the minimum license necessary to take more than 1 passenger in a flying vehicle) Compared to the population of 300 MILLION people, and you find that there are an awful few people who could "drive" a flying car. You find the economics of scale that will work at this level. Certainly, Detroit won't. Flying isn't the same as driving. There are no roads, and you have to pay careful attention to long-established procedures designed to avoid situations like running out of gas. (a minor inconvenience in a car, potentially fatal in a plane if you aren't well trained to handle it) I hate to diss flying, since I'm a pilot by hobby, and I love my hobby. But the requirements to pilot are significantly greater than the requirements to drive.

    Nuclear Fusion is widely available. Look up. (you have to go outside to see it - it's called the "sun") As a source for electricity, it's coming at prices comparable to coal [] which is the cheapest non-renewable form of energy today in the USA.

    Data storages has generally followed Moore's law, with a doubling time of about 18 months. What more do you want? I remember when a 100 MB HDD was big. Now, a little over 2 decades later, I routinely transfer files bigger than that all around the world via the Internet, and save to a flash disk the size of my thumb that requires no external power source, while my LAPTOP hard disk is 2,500 MB in size. I won't highlight my workstation/home-server with > 3 TB of storage.


    Try using a 10 year old computer sometime. You'll be amazed at just how far we've really come.

    And, technology is advancing on ALL fronts.

    I recently added on to my home, doubling its size. Along with that came new regulations for insulation, higher-efficiency heating/cooling unit, insulation, double-paned windows, etc. I DOUBLED the size of my home, but my heating/cooling bill is about HALF what it used to be. Progress? Suffice it to say that the money I'm saving on my utility bill easily beats the monthly cost of the financed retrofit upgrades to my original home! In other words: it would be cheaper to buy the upgrades to an existing 100 year old home to get these improvements than to keep using whatever you had in the first place.

    I drive a 10 year-old Saturn. It gets 30 MPG fully loaded at 90 MPH, quietly, with air conditioning, decent radio, and air bags. Back in the 1980s, I drove a VW diesel Rabbit that did about the same at the same speed. It was noisy, shook lots, had an AM-only radio, and didn't have A/C. Relative prices (inflation adjusted) makes the Saturn CHEAPER than the VW Rabbit. Hello progress ?!?

    I use CFL lights throughout my home. Over their lifetimes, they are cheaper than incandescents in replacement costs alone, and 5 of these things use less electricity than a SINGLE incandescent bulb. I can light up my whole house for what it used to cost to turn on the porch light. I've banished incandescents from my home. And, I'm still not particularly good at turning
  • Re:Supersonic Tesla (Score:3, Interesting)

    by aproposofwhat (1019098) on Wednesday January 16, 2008 @04:26AM (#22063922)
    At an average acceleration of just over 11G, you'd likely only ever do that 0-60 one time, before crashing uncontrollably after losing consciousness :P

  • Re:Dupe (Score:5, Interesting)

    by ThreeGigs (239452) on Wednesday January 16, 2008 @05:54AM (#22064342)
    giving it the sort of charge time and range as a gasoline vehicle

    Stop and think for a second, or do some math, because electric cars will *never* 'fill up' as fast as a chemically powered car. Instead of pouring in gasoline, imagine that gasoline powering a flamethrower which you point into your gas tank, and you'll have a better grasp of what it means to transfer energy directly (as in electricity) versus high density potential (like gas).

    Assume your electric car needs only 20 horsepower to maintain 60 mph.
    One horsepower is about 750 watts, assuming perfect efficiency.
    That's 15 kilowatts to keep the car going 60 mph.
    To make the numbers easy, figure 300 mile range. That means you need to drive for 5 hours.
    5 hours times 15 kilowatts is 75 kilowatt-hours.
    Now let's assume the 'electric station' supplies electricity to charge your car at 500 volts.
    75000 watt-hours divided by 500 volts equals 150 amps.
    For an hour. Assuming perfect charging.
    To get to a 3 minute charge time (one twentieth of an hour) you need 20x the amperage, or 3000 amps.

    To carry 3000 amps of current for 3 minutes without melting insulation, my numbers show you'd need copper wire about 2.5 inches in diameter (and you'd still get a temperature rise of 90 degrees farenheit over ambient). And note to electricians who may think the numbers are off, don't forget you're charging with DC voltage, not AC, so you're gonna need about 5000 circular mils worth of wire.

    I cannot imagine Joe Average plugging TWO wires, each of which is thicker than his wrist, into his car for a 3 minute recharge.

    And yeah, you could drop it to 300 amps, but then you're talking 5000 volts.

    So basically... you're never, ever going to see a 'gas station' for electric cars. They'll always be charged for long periods at home, or at 'charging garages'.
  • by Twinbee (767046) on Wednesday January 16, 2008 @08:18AM (#22065040) Homepage
    Interview with Dr. Cui, here [].
  • Re:Good deal (Score:3, Interesting)

    by Zeinfeld (263942) on Wednesday January 16, 2008 @10:05AM (#22065860) Homepage
    How about a hydroelectric dam? These are things we will need energy to make. Does a PV cell result in a net energy gain if you account for how much it took to make one? Starting with the mining processes....all the way up to installation on your roof. Its called energy accounting. My Father was doing it for ICI in the 1970s after the first oil shock. My wife now works for a consulting company that provides that type of data.

    The energy input required to make solar panels is one of the major concerns in the design process, particularly for anyone proposing cheap methods.

    Cheap, long lasting battery systems plus low cost, efficient photovoltaics would allow a large amount of residential electricity use to be met by solar. Just panel every south facing roof. At the moment the cost is high, but the intrinsic cost of manufacture is rather less.

  • by nmg196 (184961) * on Wednesday January 16, 2008 @10:16AM (#22065952)
    Point accepted, but some technologies DO come to market and work out OK in the end.

    1. I would never have believed when I was at university exactly ten years ago, that in 2008, I would have a more powerful processor in my *telephone* than I had in my desktop computer I took to uni to study Computer Science with.
    2. I would never have believed ten years ago that I could get 4 GIGABYTES of non-volatile memory in something the same size as my little fingernail (MicroSD) for a few pounds off eBay.
    3. I also bet my colleague about 3 years ago that you would NOT be able to ever run your computer from any kind of solid state hard disk until at least 2010. I lost the bet - I assumed the OS and data would get bigger faster than solid state storage would increase in size, but 64GB SSD drives are now affordable and would easily take all my files on any of my computers.
    4. We can access the Internet in the lounge, park or coffee shop at multi-megabit speeds, often for free. 10 years ago MOST people had never even heard of "broadband" and I was paying £20 per month for Demon DIAL UP at 28.8K. If you'd said that someone could get 2-8Mbit internet over shitty copper phone lines from a mile away, they'd have laughed. At the time I was struggling to make a 10Mbit work just within the confines of our office. Now our office as a 20MBit internet connection just a few years later. When I graduated from Uni in '99 (CompSci) our entire halls of residence (over 100 people) was connected back to the uni with one 64Kbit leased line - which cost the uni nearly £2000 per month. Now they have 100Mb broadband in every room connected to the uni using a laser.

    I doubt MOST people would have believed any of these things would be possible in only 8-10 years - even on slashdot but sometimes it just does happen.

    On the other hand there are some other surprises. If you expand the old graphs of PC processor clock speeds, we should have 12GHz CPUs now, but we don't. Clock speeds stopped increasing about 4 years ago. Processors are still faster due to architectural changes, faster bus speeds and more cores, but clock speeds are exactly the same if not slower than they were a few years back. My 4 year old desktop has a FASTER clock speed (2.4GHz P4) than my brand new more expensive desktop (2.2Ghz Core 2 Duo).
  • Re:Dupe (Score:1, Interesting)

    by Anonymous Coward on Wednesday January 16, 2008 @11:12AM (#22066598)
    That may work ok for $10-$20 propane tanks. I see dented and rusted ones all the time. I don't see it working anytime soon for the $500-$3000(?) batteries. Plus you'd need to have many many many multiples of them everywhere. That is a lot of investment in something that may be obsolete with the constant improvement in technology.
  • Re:Dupe (Score:4, Interesting)

    by thePowerOfGrayskull (905905) <(moc.liamg) (ta) (esidarap.cram)> on Wednesday January 16, 2008 @11:23AM (#22066754) Homepage Journal

    Isn't that a more logical (and much safer) solution to the problem?
    On the surface, yes. But that means it's perfectly plausible to get different travel distances off of each swap, because you're swapping for batteries at different stages in their overall lifespans. OTOH, keeping the same battery for its lifetime would net you a slow, predictable decline in range -- something I suspect most people would prefer, as opposed to a guessing game as to how many miles they will travel after each swap.
  • Re:Dupe (Score:3, Interesting)

    by mea37 (1201159) on Wednesday January 16, 2008 @12:32PM (#22067758)
    That might be a pretty good idea, for several reasons. But it's not a slam dunk; there are problems that would have to be resolved.

    What is the total weight of the car batteries? How much energy will be spent physically swapping them? This isn't just a starter battery... If nothing else, this would probably be the end of the self-service gas station (at least until our car-refueling robot overlords sweep in to save the day)... And remember, it's the driver that's going to end up paying for any labor, or any energy expense in general from swapping batteries.

    Another poster's concern about some batteries being in better condition than others doesn't seem like a huge deal in and of itself. The battery station is going to have to monitor the condition of the batteries in its inventory to dispose of them when they're no longer usable; so there's going to be some standard minimum: "you will get at least X out of this battery swap." Maybe you get more sometimes -- nice bonus. The station might set tiered pricing -- for an extra $x.xx you get a better guarantee about the condition of your new battery...

    However, unless the station can penalize you for degradation of the battery you turn in (relative to the condition in which you got it), there will be no incentive not to mistreat batteries. What exactly that means will depend on the battery technology, but generally some usage patterns are better for overall battery life than others. If the average battery is abused, average overall life goes down, and then cradle-to-grave energy efficiency goes down (as you have to manufacture / recycle more batteries).

    There would be overhead on the station's end to keep a sufficient inventory of charged batteries. To keep that to a minimum, there should be pretty tight standards to make all cars' batteries interchangeable. Is that currently the case in electric cars? How practical is it to have one (or at least a small number of) standard battery? (Again, we're no longer talking about the market for starter batteries here...)

    Suppose I swap out my batteries and the replacements fail catestrophically; who all has liability exposure? The station? The previous owner? The manufacturer? How do you keep track of a battery's lineage of ownership?

    Ooh, crazy Bad Hollywood Plot theory time -- a terrorist quietly assumes control of a battery station. Over the course of a few days, he swaps out the batteries from as many cars as possible, replacing them with packages that are half battery, half explosive. Once his devices are distributed, across the city vehicles start exploding at random. Film at 11.
  • by cgraves (1213828) on Wednesday January 16, 2008 @01:39PM (#22068772)
    The Slashdot summary correctly draws from the article, but the article is mis-reporting this news. It is not battery life that is being discussed but rather energy density. Capacity has never referred to battery life. The Nature Nanotechnology journal article in question (abstract [], fulltext [], pdf [] - for some reason they are all freely downloadable) reports that their Si nanowire anode has a little more than 10 times the capacity of common graphite anodes, and they have achieved that in charging and 75% of that in discharging.

    In terms of cycles, they have data in their supporting info document that shows they have only tested a cell with this electrode up to 30 cycles! So no discussion of battery life can even be made.

    Energy density can be found by knowing the capacity of each electrode, the electrolyte properties and volume, and the cell voltage (which is usually about 4 V for Li-ion batteries). They claim to have reached their theoretical maximum 4200 mAh/g capacity for a Si electrode. This is indeed ~10x the capacity of graphite anodes, which are the lowest capacity anodes used in Li-ion batteries (300-400 mAh/g). More common carbon (C6) anodes are about twice that. And, in fact, Li metal anodes have about the same capacity, 3800 to 4000 mAh/g, as these Si nanowires. So the capacity is hardly a breakthrough. However, they may be more safe than Li metal: "Li metal" batteries are Li-ion batteries with Li metal electrodes, which have had safety issues due to Li dendrites (trees) growing between electrodes and shorting out the cell. This article [] (needs subscription) from years back explains the details of electrode choices and other challenges regarding Li-ion and Li metal batteries. It seems these Si nanowire electrodes may yield similar energy density to Li metal, or several times that of the Li-ion batteries that are in common use.

It is contrary to reasoning to say that there is a vacuum or space in which there is absolutely nothing. -- Descartes