The Future For Fast-Charging Car Batteries

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Perhaps the biggest hurdle to the widespread uptake of electric cars is not their comparatively short range, but the long time it takes to re-charge the batteries. If a car like the Nissan Leaf manages only an 80-90 mile range as this test suggests (as against the manufacturers’ 108 miles from a tank of sparks) you at least want to know you can re-charge and continue your journey, as with an internal combustion engine. In practice though, a Leaf takes seven to eight hours for a full charge using a 240V – 16A outlet as in the UK. Public quick-charging points are said to give an 80% charge in about 30 minutes. That’s OK if you want to have a cup of coffee and read the papers, but you don’t want to be doing that every 80 miles on a longer journey. So faster charging that would allow, say, a 2-minute turnaround similar to refueling a conventional car could open up use of cars like the Leaf to mainstream rather than just city users.

Well, research at the University of Illinois holds out just that promise, according to an article by the Economist. Their most successful experiment has recharged to almost 100% in two minutes. In addition, the technology applies equally well to nickel hydride batteries as to lithium ion. As the article explains, a battery has two electrodes, an anode and a cathode, that are connected by an electrically conductive material”generally a liquid”called an electrolyte. Under normal discharge conditions, negatively charged electrons flow from the anode to the cathode providing a source of electric current. To balance the circuit, positively charged ions flow from the anode to cathode to balance the charges. During recharging, an external source of electrons flows in the opposite direction replacing the positively charged ions ready for discharge again in the future. The speed at which a battery recharges depends on the surface area of contact between the electrolyte and the cathode, but crucially, the amount of energy a battery can hold is dependent on the volume of the electrodes. What is needed is both a high volume and a high surface area for cathode and anode.

Dr. Paul Braun at the university has developed a process to achieve just such an outcome. His starting material is made of closely packed polystyrene spheres about 0.001 millimeters (0.00004 inches) in diameter. The next stage is to fill the gaps between the spheres with nickel by electro-deposition, similar to nickel-plating a piece of steel. After that, the material is heated, to melt the polystyrene and leave a sponge made of metallic nickel. This creates an electrically conductive framework suitable for coating with materials normally used to make cathodes such as a substance called nickel oxyhydroxide for the nickel-metal hydride version of the battery and lithium ion-spiked manganese dioxide for the lithium ion version.

The result is a charging rate 10 to 100 times faster than a normal commercial battery, but with an increase in production costs estimated to be only 20-30 percent more than current methods. 20-30 percent is not to be dismissed, as the battery is a very significant part of the cost of new electric vehicles, but for the convenience of internal combustion “refueling rates, it may be a price worth paying over the life of the car.

How far Dr. Braun’s technology is from commercial application is unclear, but if the wall of money that has poured into new battery technologies is anything to go by, there is no lack of enthusiasm out there to find just such a solution to improving charging rates.

–Stuart Burns

Comments (14)

  1. Geoff G says:

    To replace just 100 miles worth of energy in 2 minutes will require currents of the order of 5,000 Amps. The heating effect from this, in the battery and conductors, (I squared x R), is gigantic. I just don’t believe these ultra-fast charges are possible. The only way to achieve a very fast recharge is to make it chemically rechargeable, e.g. new anodes/cathodes are inserted or for a liquid battery, refilled with reactants/electrolyte.

  2. Noel Falconer says:

    Electric model aircraft fliers have been there. The batteries they use don’t charge/discharge this fast, but still melt and explode if they short. Those you describe will respond even – much! – more violently. Worse yet, they’re always ready to go BANG!, whereas petrol in a tank needs to be mixed with air before it will ignite, so is relatively safe.

  3. frankania says:

    Or, a chain of fueling stations, that LEASE you a battery pack (your car does not come with batteries).
    Thus when you needed refueling, you’d pull into the station, the attendant with the help of mechanical devices, would CHANGE your battery pack and you’d be on your way.
    Of course, the electric cars would have to be disigned for quick battery removal and replacement (not rocket-science).

  4. Joe in Oly says:

    Why not create a battery large enough that the electrolyte can be changed quickly like a gas fill-up? The filling station would leisurely, and on a massive scale, recharge the electrolyte in its “tanks” for sale vis “gas pumps” to the customers.
    Or, do I have the chemistry backward? Or, has it already been tried?
    Just musing.

  5. Toeser says:

    Why are we talking about this? Japan has already largely solved the problem. They can get a charge of around 80% in 5 minutes. I believe they may be already adding charging stations around the country based on this technology.

  6. Marc LeChasseur says:

    This souds promising, but not as much Zenn Motors (ZNN on the TSX Venture). Zenn stands for zero emissions, no noice. They have the license from a Texas company (Esstor) to produce a capacitor. Like a battery, you can peruse the technology aspect on their web-site.
    A few months ago they tested a version of an automobile that went 70 mph for 4 hours, and they recharged the capacitor in under 15 minutes!!!!

  7. Larry Oswald says:

    “I” would LIKE to HEAR more about the “charge” or “re-charge” the Japanese have developed. Sound to me like THEY have the ANSWER!

  8. Geoff G says:

    To: Marc LeChasseur
    Ultracapacitors sound great at first, but do have a couple of serious snags:
    1) They have a much lower energy density than lithium batteries (but a higher power density).
    2) Like all capacitors they have a definite “leakage current” which means, on standing all the charge gradually is lost.

    A combination of electrochemical battery working in parallel with a supercapacitor has often been proposed – the battery for total energy content and the supercapacitor for maximum power, such as acceleration.

  9. JERRY KING says:

    The solution is not in fast charging, but simply in having the battery pack mounted is such a way, that it can quickly and easily exchanged for a fresh other pack of battery already charged before at the exchange station.
    For example the batteries could be mounted in a flat support underneath the car. easily lowered mechanically, disconnected, rolled sideways, or back/forward and similarly replaced. The cost should include the new energy charge and a write of for battery pack aging.
    Jerry

  10. Xoceandove says:

    This is exactly where we need to go. If you think about the fact at least 2000 cars are on the road in any large city, every day. Then add the trucks, another 1000 or more, you begin to see the size of this issue. 24 and 7, in San Francisco, Miami, Boston, Chicago, Ft. Worth Texas and every other state that has a large city. An ocean of cars and trucks. Seriously. I can not see us destroying our planets natural resources. At the rate we are doingg so.

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