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Technical Editor Margery Conner's PowerSource streams the latest developments in electronic power design and related technologies.

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Tuesday, January 8, 2008

Silver-zinc battery technology poised to challenge lithium for energy density

Lithium ion batteries have been around since 1991. Over the years vendors such as Sony, Toshiba, and Panasonic have tinkered with the anode, cathode, and separator chemistry and structure to make them the high-energy storage devices they are today. You could make a good argument that they are almost as significant an enabler of today’s consumer electronics as the microprocessor. Try to imagine a cell phone, or an iPod, or a blue-tooth –enabled headset without energy-dense, rechargeable lithium ion batteries.

I had the chance at CES yesterday to talk with Ross Dueber, founder of the silver-zinc battery company ZPower which is a potential rival to lithium ion for energy-dense storage. Intel’s venture capital arm, Intel Capital, thinks enough of the technology’s future that it’s financially backing ZPower, a significant vot of confidence. Dueber was on the CES panel, Top 10 Technologies You’ve Never Heard Of.”

Silver-zinc chemistry has three significant advantages over lithium ion, according to Dueber: It’s inherently safer because it lacks the volatile cathode makeup that leads to a thermal runaway, it’s very green since both silver and zinc are non-toxic as well as recyclable, and, perhaps most importantly, it packs 40% more energy into a battery pack than lithium ion can.

Silver-zinc has a long history that pre-dates ZPower. It was used by the military and aerospace where programs could afford to pay for the higher-priced silver in exchange for increased energy density. However, it was not rechargeable. ZPower’s contribution has been to tweak with the silver-zinc formulation to make the batteries rechargeable. But now that ZPower has the chemistry down pat, there’s still the two-pronged challenge of developing a widespread manufacturing base (think of the number of Chinese lithium ion battery vendors) as well as introducing design engineers to silver-zinc’s different charge-discharge profile.

ZPower is presently using Tyco on a contract basis to both manufacture the cells and battery packs for a laptop vendor that should announce a silver-zinc-powered laptop in 2008. In the meantime, ZPower has worked with TI to develop tweaked versions of TI’s battery-charging ICs to simplify incorporating silver-zinc batteries into portable designs. Lithium ion may have a 15-year head start, but it looks like it has a strong competing technology going forward.

[Note: Check the PowerSource post with the comment from Gannon & Scott agreeing with the recyclability of the technology.]

Related entries in: Battery Power | Power Sources/Controllers |

Reader Comments

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at 1/8/2008 11:53:15 AM, number1bigboy said:
How does the cost of silver come into the equation, if at all?

at 1/8/2008 1:52:19 PM, J. Williams said:
Silver zinc with a KOH electrolyte is rechargeable. That is not new. It's been around for decades in military systems. As for energy density, by volume, Ag-Zn may have better energy density, but by weight it's a wash. However, as I have experience in a program that used a Ag-Zn battery of over a megawatt hour, the reliability was not good at the higher energy densities. Dendrite formation was probably the biggest bugaboo. Unfortunately, the battery would only tolerate about 5 to 20 charge cycles before needing replacement due to cell shorts from dendrite formations puncturing the cell separators. As for safety, the KOH Ag-Zn battery has issues with both H2 and O2 production. Doesn't that sound explosive? The plates may be non-toxic but the electrolyte can be nasty. KOH is a main ingredient in drain cleaners, very caustic. The charging of the cells have to be watched carefully. I don't know what chemistry ZPower are proposing, but I don't see Ag-Zn taking over Li-ion anytime soon. By the way, this military program has now been using a 1.3 MWHr Li-ion battery very sucessfully for over two years.

at 1/8/2008 3:10:49 PM, Meredith Poor said:
KOH (potassium hydroxide) is quite caustic but once it mixes with chlorine (or other halogen) it becomes a common salt. People use KCl as a salt substitute on their food.

at 1/9/2008 5:41:57 AM, PAUL said:
Surely this is yet another demand on silver (price increase!) that it will struggle to fulfil along with all of the new uses such as Hospital anti bacterial uses etc. etc. etc. Is there no end to this wonder metals' usefuleness!???

at 1/9/2008 11:01:06 AM, Bo said:
Just my prediction, within 5~10 years, Li-ion battery will increase the energy density by 10 fold using nano technology. And the fire safety issue will be solved by then. The car industry will be the biggest driver for Li-ion battery improvement. Silver battery may have it's place. But challenge Li-ion? The chance is slim.

at 1/9/2008 11:28:25 AM, JIMB said:
Bo, where does 10x come from? Have you considered the theoretical limits? I think the existing cells are WELL beyond 10% of the theoretical limit.

at 1/9/2008 3:38:15 PM, Tycho said:
In the last 100 years, I don't think any battery chemistry has improved 10x in energy density. New chemistries have arrived, but even those haven't beaten lead-acid by much more than a factor of ten. If there is a Moore's law of batteries, it would be something like 2x every 30 years.

at 1/10/2008 10:39:56 PM, John Faraday said:
How long has ZPower been in business, and what batteries have they sold? If this is such a good idea wouldn't we see competition?

at 1/11/2008 4:30:42 PM, Fond of Zpower said:
Z power (formly Zinc Matrix Power) has been around for about 15 years on a primarily R&D basis. As noted by user: J. Williams there have been many issues with the development of new chemistry that will make a battery; however those kinks have been (slowly but surly) resolved. The cost of silver does come into play, it is a vital component of the battery. With that being said I'm sure they have figured out a way to recycle the silver so maybe you would pay a lot for the battery upfront but once it's dead you'd get a large sum of money back. Competition has previsouly developed but because the amount of time Zpower has put into R&D I believe it would take another company decades to catch up.

at 1/15/2008 11:02:58 AM, Meredith Poor said:
Someone from Stanford has announced a 10x LiIon energy density improvement using silicon nanowires. Do a keyword search on "Stanford LiIon Silicon Nanowire". They're claiming commercialization in less than five years.

at 1/22/2008 3:27:36 PM, GDBryan39 said:
We need to face it: Better lead acid is the way to go if you don't need to haul it anywhere. Better lead acid batteries once were and can be again. If your foundation can hold it up, use lead acid. If you have to move it around, we do need the other batteries for sure. Electric cars could be run from the street under the car most of the time if we would plan it right and then do it. That way we only need to power the vehicle for short distances for off ramps and byways. Why not use the road way as a power source. That is especially true of trains which always go down the same tracks day after day. Who says all the powere has to reside in the car.

at 1/22/2008 3:29:46 PM, GDBryan39 said:
We need to face it: Better lead acid is the way to go if you don''t need to haul it anywhere. Better lead acid batteries once were and can be again. If your foundation can hold it up, use lead acid. If you have to move it around, we do need the other batteries for sure. Electric cars could be run from the street under the car most of the time if we would plan it right and then do it. That way we only need to power the vehicle for short distances for off ramps and byways. Why not use the road way as a power source. That is especially true of trains which always go down the same tracks day after day. Who says all the powere has to reside in the car.

at 1/23/2008 8:53:13 AM, Dan said:
J. Williams said it ALL. Good Post

at 3/9/2008 9:25:13 PM, joe said:
Intel would not invest if it was not ready for prime time. I know I would pay a premium for the 40 percent run time improvement, that is one of the most important things for me in a laptop since I travel constantly doing software consulting. I really don't care about the safety or environmental features, although I suppose it doesn't hurt to have the warm fuzzy eco thing. The people posting here saying Lithium ion is going to improve rapidly do not know what they are talking about. Lithium Ion is a very mature technology. So, a new technology that beats lithium ion by 40 percent out of the gate is very encouraging. Maybe I will to my silver miners portfolio.

at 6/16/2008 7:09:32 PM, AgZn said:
Two points. 1) The 1.2 Megawatt Li-Ion battery referred to above, cost 6x to 10x more the Silver-Zinc battery it replaced. Also not sure how its doing now a days, since the program was canceled. 2) If Li-Ion is so safe, why can't it fly in a commercial airline? Even a box of coin (Dime size) Li-Ion cells can't fly. And if you try to bring a spare Lap top battery onboard, expect it to be confiscated as a safety hazard!

at 7/10/2008 8:32:56 AM, ChrisPE said:
Good article Margery. I remember making a comment about military technology batteries when we talked about electric cars.It happens to be that way that all big technical gadgets(calculators,lcd screens....)are a "fallout" of military ,so now after submarines used it for several decades (an they were rechargeable) we are blessed with a new version of 40 year old technology.I guess that it boils down to a fact that if we REALLY want something ,we can get it.Let's get that technology and make it popular , before speculators buy out all silver and oil moguls start writing nonsence articles of dangers connected with Silver-Zinc batteries.

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