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Published on July 28th, 2014 | by Tina Casey


Stanford Foresees $25,000, 300-Mile EV Battery Range With New Honeycomb Battery

July 28th, 2014 by  

A research team from the Stanford School of Engineering has just figured out how to stabilize the lithium in a lithium-ion battery, and that could help bring the typical EV down to the level of mainstream affordability. The team is looking at a price point of $25,000 for an EV battery range of 300 miles, which would be competitive with a 40 mpg gasmobile.

The dream of extending EV battery range usually comes with a high price tag (here and here, for example), so the idea that longer range could actually bring down costs is of particular interest, especially considering that former Energy Secretary Steven Chu is a member of that Standford research team.

low cost EV battery

Honeycomb (cropped) by prilfish.

Dendrites Are Attacking The Ship, Captain!

We love the word dendrite because it sounds like one of those evil alien creatures from Star Trek’s cheap season (oh wait, they were all cheap seasons), but in real life dendrites really are evil, at least for Li-ion batteries.

Our sister site Gas2.org took note of Chu’s interest in solving the dendrite problem back in 2008, before he embarked on a detour as Energy Secretary.

Now that Chu is back at his former position with Stanford Engineering, he has joined with research team leader Yi Cui and lead author Guangyuan Zheng in a paper published online yesterday in Nature Nanotechnology, titled “Interconnected hollow carbon nanospheres for stable lithium metal anodes,” which zeroes in on the dendrite problem.

Dendrites refers to those hairy mossy fibers that can grow out of your Li-ion battery over time. They are associated with decreased efficiency as well as safety risks. Our friends over at Lawrence Berkeley Laboratory offer a good rundown (break added for clarity):

Over the course of several battery charge/discharge cycles, particularly when the battery is cycled at a fast rate, microscopic fibers of lithium, called “dendrites,” sprout from the surface of the lithium electrode and spread like kudzu across the electrolyte until they reach the other electrode.

An electrical current passing through these dendrites can short-circuit the battery, causing it to rapidly overheat and in some instances catch fire.

The kudzu reference is to that weedy vine that has been swallowing up the southeastern US, btw.

Three Problems For Li-ion EV Battery Range

For those of you new to the subject, a Li-ion battery has two electrodes, an anode and a cathode. As the battery is discharging, electrons move from the anode to the cathode through a solution (or a solid) called an electrolyte.

The lithium in a Li-ion battery is in the electrolyte, not the anode or the cathode. A typical Li-ion battery has an anode made of graphite or silicon. Lithium would be a far more efficient choice, but that’s where the dendrite problem comes in.

Lithium expands during charging, to a degree far more extreme than silicon or graphite. That leaves an uneven surface. Lithium ions that are attracted to the anode from the electrolyte escape through pits and cracks. The result is a mossy growth, aka dendrites.

Dendrites aren’t the only problem, though. As described by Stanford, extending Li-ion EV battery range also depends on improving management of the chemical reaction between a lithium anode and the electrolyte, in order to prevent the anode from “using up” the electrolyte.

A third, related issue involves managing the heat that results from the interaction between a lithium anode and an electrolyte.

The Honeycomb Solution

Standford’s solution is a “honeycomb” of interlocking carbon nanospheres layered on to the lithium anode. At 20 nanometers thick you’d need 5,000 layers of this nano-comb to equal the width of a human hair, but it seems to have gotten the job done.

The honeycomb structure is flexible enough to stabilize the anode surface as it expands during charging, and also while it contracts during discharge.

According to Stanford, the results so far look promising. In tests the new lithium anode reached 99 percent efficiency over the course of 150 charge/discharge cycles.


The figure of 99 percent is significant because a marketable battery needs to be 99.9 percent efficient over numerous charging cycles (that’s Coulombic efficiency for those of you keeping score at home). Earlier attempts at lithium anodes have petered out pretty quickly, attaining a top mark of 99.6 percent at the beginning and dropping down to 50 percent efficiency after just 100 cycles.

In batteryspeak that figure of 99.6 percent is significantly lower than the desired 99.9 percent. By the same token Standford’s achievement of 99 percent over 150 cycles is pretty impressive and it comes a lot closer to commercial viability, but it does fall short of the desired 99.9 percent mark.

The next steps for Standford include tinkering around with the electrolytes, perhaps trying out some new ones.

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About the Author

specializes in military and corporate sustainability, advanced technology, emerging materials, biofuels, and water and wastewater issues. Tina’s articles are reposted frequently on Reuters, Scientific American, and many other sites. Views expressed are her own. Follow her on Twitter @TinaMCasey and Google+.

  • aseuss

    As an example this phys.org article [http://phys.org/news/2014-07-holy-grail-battery-stable-lithium.html] refers to the researchers by name throughout the article, rather than saying “According to Stanford” or “The next step for Standford” or “As described by Standford [sic]”. The Stanford website article quotes the guys directly–there wasn’t a Stanford spokesperson, it was just these guys talking about their own study.

  • aseuss

    Why does the writer, Tina Casey, keep referring to the Cui and Zheng as “Standford”[sic]? I’ve never heard anyone say “The next step for Cornell” or “As described by Pennsylvania” or “By the same token, Dartmouth’s achievement”, to substitute university names for people. Usually writers just quote the person’s name: “As described by Jones…” Maybe “As described by Cui” or “According to Cui and Zheng” doesn’t sound right. Hmmm. By the way, I don’t think our Stanford University friends like being referred to as ‘Standford’. Now everyone in the comments section is referring to these guys as ‘Standford’.

    • TinaCasey

      Glad you asked. It’s important to give credit where credit is due, but In the interest of accommodating new readers as well as those familiar with the field, I try to avoid cluttering the text with personal names that don’t resonate outside of their field. If you follow my links you can find the original sources. Also as an aside, having worked many years in team situations I feel more comfortable giving voice to the institution that supports the team.

  • aseuss

    Looks like Chu has bounced back from a lackluster tenure as Energy secretary. He’s actually doing something concrete about the energy problem, well over a year after quitting as Secretary of Energy, rather than just dole out money to terrible energy firms.

  • Each transit ride is currently subsidized $8 by the government, in our Municipality.
    These multi-thou. charge batteries would be bought by governments for Google busses and many other vehicles used ’24 hours a day’.

  • TinaCasey

    Sorry ’bout that headline guys. Figured we’d gotten past the days of $25,000 EV batteries…that figure refers to Energy Secretary Chu’s vision of achieving a reasonably priced BEV (that means battery plus wheels, seats and all that other stuff) at around $25,000, including a battery with a nice range of about 300 miles. Here’s the link again to his remark: http://www.eurekalert.org/pub_releases/2014-07/ssoe-sta072514.php

    Also thanks to whoever brought up the point that battery range has a usefulness cap, which would be the amount of time a typical driver usually spends on the road without a break. If your personal limit is only a couple of hours, you’re not going to need to invest in a particularly large battery (that leads to a related issue, which is the amount of time you’d need to spend recharging but whatevs).


    • Bob_Wallace

      The Tesla supercharger is about 130 miles in 20 minutes, 170 miles in 30 minutes.

      I think the magic number is ~200 miles. That would make for a 500 mile day with about 50 minutes spend charging.

      When we start talking about 300, 400, 500 mile ranges we risk estimating very high purchase prices to cover the extra range. And we add on weight that we just don’t need to haul around.

      Assuming supercharger bays are about $35,000 it makes more sense to me to go with moderate range batteries, sell cars for less, and give people plenty places to charge when they take a long trip.

    • Calamity_Jean

      I agree. I need a stretch break about every two hours. If I could count on finding a charging station at that point I’d be willing to stay a while longer (and buy a snack). Companies that cater to long-distance drivers will soon be able to increase their business if they make charging stations available.

  • Henry WA

    The title and later text should be corrected to “a $25,000 EV with a 300 mpg battery”
    In the real world and for most owners 150 full cycles plus 2000 partial cycles of 30% or less would give at least a 10 year battery life

  • Roger Pham

    Toyota hinted recently that they should be able to deliver an EV capable of 300-mile range for $25,000 in today’s dollar by 2020-2023 or so, using Hydrogen-Air battery. This same type of EV will be available next year for $69,000. The Japanese govt will subsidize $20,000 off the price of each of these EV sold, and are building a network of 100 stations of super fast charging stations capable of charging from 0 to 100% in 3 minutes.

    • Bob_Wallace

      Roger, that’s a tired old game. You’ve overplayed it.

      Please stop trying to confuse people with your Hydrogen-Air battery stuff. Expect future attempts to disappear.

      FCEVs might fall to $25,000. If manufacturing volumes rise to 100,000 per year. You failed to include that.

      A FCEV for $70k next year. In a lower end SUV package.

      We can buy luxury EVs with almost as much range right now for $70k. We can plug them in when we park and not have to wait for someone to build H2 fueling station. We can drive across country right now – no H2 fueling stations needed.

      And we can drive for less than half as much per mile.

      • Roger Pham

        Thanks for the feedback, Bob. It is important to compare one battery tech to another to get an overall perspective.
        The Holygrail in battery for 300-mile-range EV with 3-minute recharge has been reached, especially when one consider a Tesla Model S having 15-20 kWh Li-ion battery for daily commute plus a 133-kWh extended Metal-Air battery for long range plus ultra-fast charge in 3-5 minutes. Tesla has already filed a patent for such a concept. If one would look in the Periodic table, Hydrogen is on the top left side on the Metal side, so, it is chemically a metal. It can readily donate electron just like any other metals.

        I wish that the BEV community would be more accepting of Hydrogen-Air battery instead of rejecting just because it was advanced by President GWB and not by Al Gore and rejected by Pres. Obama and Secretary Chu.

        H2 filling stations are being built in California, Europe, Japan, Korea, and with increasing momentum, will come to the rest of US states.

        • Bob_Wallace

          There is no “hydrogen-air” battery.

          Hydrogen could be used in fuel cells. Hydrogen, if made from renewable energy would be a clean storage methodology, but it is not a battery. It does not produce electricity but works as fuel.

          Is that clear enough for you?

          You were asked to not continue attempting to confuse people.

          • Roger Pham

            What about Aluminum-Air battery? The Aluminum is actually consumed in the electrochemical reaction, yet Tesla patent still refer to it as a Metal-Air battery. Some people refer to it as a fuel cell. It all in the semantic…call it however you want…

            I would like to see faster adoption of EV’s that use clean RE, to help solve climate and environmental issues, just like Mr. Musk would want the same. I like to see Tesla grow real big to rule the auto industry. To get to that, it is important to put one’s pride aside, like I’m doing now, and consider all types of batteries and technologies.

            Keep up your good work, Bob. Humanity will need it.

          • Bob_Wallace

            Roger, please do not post stuff about “hydrogen-air” batteries. Those of us who are familiar with you know you’re trying to sneak FCEVs into the discussion.

            If you want to talk about fuel cells, then talk about fuel cells. Then people will understand your comment.

            There’s no problem at all with considering the options. That is only wise. But there is a very large problem on this site with distortion and attempts to confuse.

            Bring on the options. But do it in an honest and forthright manner. Point out not just the pluses but also the negatives that you know about.

          • Roger Pham

            Negatives of H2-FC are bulk, packaging problem, and lack of familiarity by the industry and some people have fear of H2. The Toyota FCV has little trunk space due to the size of the H2 tank and battery pack. Tesla has a way of packaging the battery and even the FC on the floor as a thin layer, while having two H2 tank of 2 kg, one under the front seat bench and one under the rear seat bench, leaving the trunk space intact.

            Negatives of Aluminum-Air battery are inefficiency, with source-to-wheel efficiency of only 15% vs H2-FC of 34%, and help required with changing the aluminum plates, time required not stated, while H2 fillup is much easier. For this reason, heavy-duty EV will likely use H2 instead of Al for energy, and H2 station will be much easier to find.

          • Bob_Wallace

            “Negatives of H2-FC are bulk, packaging problem, and lack of familiarity by the industry and some people have fear of H2.”

            You missed the lack of fueling infrastructure and the higher cost per mile of operation. I’m not sure fear of H2 is playing a big role.

            I think you are engaging in very wishful thinking re: a fuel cell PHEV. It’s more likely we’ll get ~200 mile range EVs and have no use for fuel extenders. We should have a much better idea by the time a few dozen FCEVs have been sold. At that point the investment sector could pull the plug on H2. If there is reasonable expectation of affordable, adequate range EVs we’ll stick with ICE PHEVs as we wait for batteries to get to 200 miles.

    • aseuss

      Toyota’s been beat in the electric game, so they’re going Hydrogen fuel cell, not Hydrogen-Air battery. Tesla will probably crack the sub-$40,000 electric car market with new batteries from Panasonic-Sanyo, which currently supplies Tesla’s Model S.

  • GeekToTheBone83 .

    “As the battery is discharging, electrons move from the anode to the
    cathode through a solution (or a solid) called an electrolyte.”

    Almost. The electrolyte is conductive to ions, but NOT electrons. The electrons have to take the long way around, through whatever the battery is powering.

  • aaron bowersock

    Nice to see updates and innovation on this tech from an entity that’s not Tesla. While they are moving mountains when it comes to popularizing EVs and improving battery tech, diversity is always welcome. Different teams may find different solutions, and with the recent opening of patents, eventually the consumer (and an environment fit for humans) will win.

  • bornu

    Comparable to 40mpg? Hardly impressive. The Tesla S gets the equivalent of 95 mpg, with improvements in efficiency, cost, and range in the short-term outlook.

    • Tony A

      You misread – note that the reference to a 40mpg indicated that the PRICE would be competitive with a 40mpg car. Not perform like one!

  • Jesse Schulman

    The Tesla S already has a 300 mile range, and the battery on that car costed about $30k back in 2008. So how is this new news?

    • Mustafinho

      Its new news because 25K would be the price for the CAR(not just the battery) with 300 mile range!

      • Jason Willhite

        I think the title is misleading. I think the abbreviation ‘EV’ in the title is an adjective describing the battery. The battery will cost $25000. Also, I was unclear the relation between the work that is being done here and how it relates to a cheaper battery.

    • Tony A

      You misread – note that the cost of the WHOLE CAR would allegedly be about $25k, not just the battery.

      • Jason Willhite

        I think the abbreviation ‘EV’ in the title is not a noun. It’s is an adjective describing the battery.

  • Larry

    Even if “Just the battery” is 25k, it would be commercially viable. Not to mention the cost efficiencies of mass production. It seems like these type of announcements are starting to come more frequently. Holy grail indeed!

    • Tony A

      I know Elon hasn’t publicly commented on new battery tech, but if developments like this could be leveraged against something like the planned battery gigafactories, it’d be very interesting indeed.

  • SammyVThompson

    By the same token Standford’s achievement of 99 percent over 150 cycles is pretty impressive and it comes a lot closer to commercial viability, but it does fall short of the desired 99.9 percent mark. http://moourl.com/z2gt1

  • franklingray

    150 cycles is your test. Come on man, try minimum of 1,000, preferably 2,000 cycles. We need to know if that stuff can last. Or will it erode and then the battery still catches on fire, just later.

    • Bob_Wallace

      500 cycles in a 300 mile range EV would be a decent minimum. At 150,000 miles the car would still have 80% or 240 miles left and be an excellent second car or primary drive for someone with a limited budget.

      In fact, with a 300 mile range EV less than 500 cycles would be fine. As long as the car could make it past 100K with at least a 200 mile range I would think it acceptable.

    • jeffhre

      2000 cycles at 300 miles gives an EV battery a 600,000 mile lifespan with 75-80% capacity left. Not too shabby with respect to aspirations!

      How many drive-trains on internal combustion propelled vessels (or $25,000 cars) will be serviceable upon reaching the equivalent hours of a car with 600,000 miles, and no major component replacement?

  • JamesWimberley

    They have an experimental battery that has run for 150 cycles. The price of the car is just PR handwaving.

  • Kite23

    need the entire car to be able to be priced at $25,000 after fees etc. for the masses to be able to afford it.

    • jeffhre

      The “average” price of a new US car is over $32,000.

      • Kite23

        and most of Americans buy used or much lower priced than that. Average America doesnt buy cars like someone would buy new socks

  • James Elliott

    Is the $25,000 price referring to the cost of just the battery, or an entire EV built around the battery with 300-mile range? It’s a bit difficult to tell, and one of these is much more impressive than the other.

    • Doug Cutler

      Pretty sure they are referring to the price of the car not just the battery pack. Here is a quote from Chu from a different post on the same story:

      “In practical terms, if we can improve the capacity of batteries to,
      say, four times today’s, that would be exciting. You might be able to
      have cell phone with double or triple the battery life or an electric
      car with a range of 300 miles that cost only $25,000 — competitive with
      an internal combustion engine getting 40 mpg,” Chu said.

      But please note though: “you might be able to”. Something a little more emphatic would be nice. Valley of Death lies between lab and market, most never make it. We wait hopefully on the other side.

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