Seth Fletcher from Popular Science and GM's director of Global Battery Systems Bill Wallace hosted a webchat Sept. 23. Fletcher is the author of “Bottled Lightning: Superbatteries, Electric Cars” and the new “Lithium Economy.”
Q- Is there a Moore’s Law for the batteries? (i.e. how long does it take for the battery capacity to double for the same volume, price etc..)
A- Bill Wallace: There is no Moore's law for battery technology evolution. However, we are aggressively pursuing both energy density and cost reduction improvements in our product. In general, we see significant improvements in 3-5 years, with smaller incremental improvement sooner.
Q- Will batteries ever be able to replace the combustion engine?
A- Seth Fletcher: Tough question. I'm using rough numbers here, but to match the energy density of gasoline or diesel fuel, we need a battery that can store about 2,000 watt-hours per kilogram. (Gasoline stores 13,000 wh/kg, but only a fraction of that is usable.) Lithium-ion is theoretically limited to about 400 wh/kg. Chemistries such as lithium-sulfur and lithium-air might be able to exceed 2,000 wh/kg, and many smart scientists around the world are developing those batteries on a lab scale, but it's hard to say whether they'll scale up well enough to use in transportation.
Q- Can you talk to GM's current and future plans for end of life usage/recycling of the Volt batteries?
A- GM has a partnership with grid management supplier ABB to develop prototypes of electric storage solutions for improved grid reliability using Volt batteries after they've reached the end of their useful life in the vehicle. We recently showed an early version of the prototype at ABB's R&D facility in Raleigh, N.C., and expect to have a prototype in the field next year. We're also studying solutions that will use Volt batteries in secondary applications to store renewable energy for use on the grid.
Q- Any chance you guys will be making the batteries in America? I continually hear that East Asia has all the supporting industries so it wouldn't be economical. However, I don't understand how our vast intellectual resources could not quickly bring us back to a competitive position.
A- Seth Fletcher: David, I can't speak for GM, but I can say that I've seen a tremendous amount of activity aimed at establishing a domestic lithium-ion battery industry. Thing is, it'll take time and continued support to make it happen, and historically this country hasn't been very patient and far-sighted about this sort of thing. Most of the IP that underpins today's lithium-ion batteries were developed in the West and then effectively handed over to Asian electronics manufacturers. Now we're struggling to catch up. It won't happen overnight, and it definitely won't happen if our political system decides not to support this nascent industry long enough for it to succeed on its own.
Q- What makes the Volt battery different from other battery/gas operated vehicles?
A- Bill Wallace: The Volt battery is unique because it delivers both high power as well as high energy, helping the Volt deliver full electric driving under all conditions, unlike a traditional hybrid which must rely on its engine during high power demands. High energy density allows our compact battery to deliver an EPA-estimated 35 miles of full electric range.
Q- What advancements over say a laptop battery do the volt batteries have?
A- Bill Wallace: The primary advantage of the Volt battery is extended user life, which, compared to a typical laptop battery, lasts ten times longer. In addition, the Volt battery can also deliver the power required for rapid acceleration. Laptop batteries are only able to deliver power at a low and constant rate.
Q- Are you looking into renewable sources for new batteries? Or just looking to make Li-Ion batteries more efficient? The problem I see with Li-Ion batteries is that we must import the Lithium from Afghanistan or elsewhere. How can we avoid the looming problem of running out of Lithium?
A- Seth Fletcher: Please don't let anyone ever tell you we're going to run out of lithium. Lithium is very different from the rare earths (some of which genuinely are a problem). Lithium is cheap, abundant, easy to mine and recyclable. Most battery-grade lithium currently comes from Chile, an extremely friendly country. Then there's Argentina, Australia and Bolivia have huge reserves, but we don't need them. We won't need lithium from Afghanistan for probably 100 years. And the U.S. actually has a few very large lithium deposits -- one in particular is being developed right now by an interesting company called Western Lithium, operating in northern Nevada.[PAGEBREAK]
Q- What is the effect on long term battery life due to routine rapid charging (>50kW)?
A- Bill Wallace: Rapid charging, while convenient for the customer, does decrease battery life. Therefore, the battery thermal management system can be designed to help reduce that performance loss.
Q- Do either of you want to comment on the viability EEStor?
A- Seth Fletcher: EEStor, which says they have a breakthrough supercapacitor design, has captured many imaginations, but as far as I know they've never demonstrated their technology for any independent observers. Until they do, the only responsible attitude is to be extremely skeptical.
Q- I know how long the Volt battery is guaranteed for, but how long do you think the useful life really is? As an early adopter I would like to think that the car would have resale value after 8 years.
A- Bill Wallace: For those of you who don't know, the Volt's battery is warrantied for 8-years/100,000 miles. Engineers at our Global Battery Systems Lab here in Warren (where I'm doing this chat today. It's the largest automotive battery lab in North America) have tested the Volt's battery packs for more than double that amount of miles. We are confident that the Volt will prove its value well beyond the warranty period.
Q- When the Volt is parked in the garage I can sometimes hear a pump going. I've assumed this is for cooling the battery (not cold enough here for heating). Is that right and, if so, what exactly is happening and why?
A- Bill Wallace: Hi Don, yes, that's right. The pump is cooling the charger and the battery to ensure high efficiency charging and maximum battery life.
Q- I know that the Volt's battery is liquid cooled, which makes it a one of a kind. It seems as though nobody else is going to a liquid cooled battery at this time. Is this something GM will continue to pursue in the future? Or is it not cost efficient to stick with a liquid cooled battery?
A- Bill Wallace: We've always been strong proponents of a liquid-cooled battery because of its compactness and its advantages for battery life. You bet that it is something we will pursue in the future and we're likely to see others join us as well.
Q- Do you see the electric utilities being able to keep pace with the adoption of electric vehicle technology?
A- Seth Fletcher: Utilities insist that they'll be able to keep pace, and most independent studies confirm that. A 2006 study from PNNL found that the U.S. could convert 70 percent of its auto fleet to electric drive without adding new generating capacity. They made some overoptimistic assumptions about the way people will use their cars, but still … The biggest issue is that if you get a few EVs in a cul-de-sac with an old transformer, it might blow the transformer, and that's why utilities are trying to locate EV buyers early on. But that's a local issue, not a large-scale generating-capacity issue.
Q- How will the battery R&D work done at the new GM China Advanced Technical Center in Shanghai impact/coordinate with the efforts here at GM NA?
A- Bill Wallace: Scott, the China Battery R&D Center, which opened last week, is tightly linked with our battery lab here in Warren. The lab here will remain the hub of our battery research and we will now be able to collaborate with our China team to do additional research on technologies that may be available in that part of the world.
Q- Are you guys more focused on additional capacity or reduced weight for the next generation of Volt Batteries? I'm wondering about 12kw packs, 24kw packs...etc. Where's the attention going?
A- Bill Wallace: Cody, I'm going to cheat here. We're actually focused on both. By improving energy density, it will result in lighter, smaller batteries for our customers in the future, which will improve affordability and performance for you.
Q- From my understanding all PHEV and full EV are using Li-ion batteries and will continue to do so in the near future. Can you comment on any trends you see with respect to NiMH and regular HEV? Do you think as Li-ion prices decline we will see a switch?
A- Seth Fletcher: Over the past couple years a lot of automakers have begun to move toward lithium-ion even for conventional hybrid applications. Buick eAssist is one example, and Ford is doing the same. So is Hyundai, etc. That will quickly drive down costs. I wish I could get carmakers to tell me know much they're actually paying for batteries and how much they will be in a few years — they're very skilled at not giving reporters those numbers! — but I think it's pretty clear that prices are dropping and will continue to drop rapidly in the next several years.[PAGEBREAK]
Q- The Chevy volt uses a 3.3 kw charger, the Ford Focus Electric will be using a 6 kw charger. Do you see Chevy putting a higher power charger in? The Level 2 standard will support up to 15 kw.
A- Bill Wallace: The 6.6 is only relative to places where you can get a 240v charge and is ideal for full battery electric vehicles, which requires significantly longer charge times. The Volt's range-extending capability allows us to use a battery that can be charged in only four hours using 3.3 kw.
Q- What chemistry lithium batteries are used in the Volt?
A- Seth Fletcher: Unless Bill wants to correct me, I'll do this one — the simple answer is that LG Chem's cells use lithium manganese spinel cathodes. But earlier this year Mohamed Alamgir from LG Chem admitted that LG blends in some nickel-manganese-cobalt, which was developed by Argonne. So it's a blend.
Q- What voltage does the Volt's battery operate at?
A- The average voltage is 360v with up to 400 amps delivered during aggressive driving.
Q- Bill, what's the metric by which you measure battery goodness by? Are you focused on $/kwh, $/kw, lbs/kwh or lbs/kw?
A- Bill Wallace: We focus on $/kwh, $/kw and kwh/L in our future designs.
Q- Intellectual property has been mentioned a few times here. I've often wondered if part of the reason certain car companies overstate the problems with electric vehicles is that they don't have the IP to compete. Do you think that is a factor?
A- Seth Fletcher: I promise I'm not saying this because we're on GM turf, but when I was working on the book I had a few battery-industry insiders tell me that they suspected Toyota exaggerated the problems with lithium-ion batteries because their battery partner, Panasonic, was behind on lithium-ion. Since then, of course, Panasonic has bought Sanyo and formed a battery juggernaut. And next year, Panasonic is set to release an 18650 cell with a silicon alloy in the anode, for a big boost in energy density. So make of that what you will.
Q- How did you arrive at the decision to use large format cells in the Volt battery as opposed to a larger number of smaller cells, such as the standard 18650 that is in large volume production (inexpensive)? P.s. I love my Volt. I've had it since January and am averaging about 200mpg!
A- Bill Wallace: We're glad you love your Volt! You might be surprised to learn that large format batteries are actually less expensive to produce in high volume and high capacity than small format batteries like the 18650, and that's why we use them. They're also easier to cool.
Q- I am from Sweden, and we can have really cold winters. When a battery gets cold it’s not working as well. Will there be a solution to this or will Sweden have to have bigger battery packs to compensate for this?
A- Bill Wallace: The range loss on the Volt's battery in extremely cold weather isn't the result of reduced energy capacity because we do maintain optimal battery temperature using our liquid-cooling system. The loss is actually the result of heating the cabin and defrosting the windshield. That can be minimized by using the Volt's convenient pre-conditioning feature available on the mobile app. That uses energy from the grid while charging to heat the cabin and defrost the windows.
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