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Those damn Germans (And their New Li Ion Battery)

Discussion in 'Battery Discussion' started by Bperry, Jun 4, 2013.

  1. Bperry

    Bperry Member

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  2. wraithnot

    wraithnot Model S VIN #5785

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    Since they mentioned the power density, but didn't mention the energy density, I'm suspicious that the energy density isn't all that good. They hint at this here: Green Car Congress: ZSW develops process for Li-ion batteries with extended cycle life; 10,000 charge cycles

    "The balancing of electrodes means that the electrodes must be adjusted because the complete lithium is introduced by the positive electrode. Otherwise, when the electrodes are not adjusted this could lead to a lithium deposition on the surface of the negative electrode. Therefore the negative electrode (anode) was oversized to avoid the lithium deposition on the anode surface. The balancing of the electrode must be performed as accurately as possible. A high oversizing of the anode leads to a loss of energy density of the complete cell. One the other hand an oversizing of the cathode results in lithium deposition on the anode surface."
     
  3. Bperry

    Bperry Member

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    I'm not saying that we'd get much more energy out of these, but the longevity of the batteries is much improved. And we'll never have to change the batteries again due to degradation.

    The power density they mentioned 1100 W/kg in the 18650 form factor, compares to the upper bound for current LiIon Batteries is 340 W/kg (according to wikipedia). I realize this doesn't mean we'll have 4x the joules, so much as we'll have 4x the joules per second. We may still have only 300 mi on our 85kWh batteries, but we'll have ~300 for 27 years.
     
  4. PhilBa

    PhilBa Active Member

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    You can drive yourself crazy reading research announcements about this or that battery technology "breakthrough" and then regretting a purchase decision. 90% or more of those never make it into actually production designs. There are all sorts of discoveries that improve density, power, internal resistance and lifetime but even if they actually get adopted, it will be YEARS before you see products with them. So, relax, have a homebrew.
     
  5. Johann Koeber

    Johann Koeber Member

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    Sorry, a German speaking here ;)


    The battery in my Lexus 450h Hybrid car is charged and discharged constantly. Its capacity was just enough to travel 2 km - using electricity alone. It is seldom (if ever) in neutral. Either it is being charged, or it is delivering power.

    I have driven the car over 305,000 km (ca. 200,000 miles) so far.


    No noticable degradation of the battery. I assume they are using only a small part of the capacity, like 60% to 75% SOC. Maybe the electronics are also hiding battery degradation from me - who knows.

    It just shows that cycling a battery 100.000 times does not neccessarily render it useless.
     
  6. Johan

    Johan Took a TSLA bear test. Came back negative.

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    Those batteries, just like the NiMH batteries in the Prius, are kept as you say in a very tight SOC-range. Therefore I wouldn't call it 100.000 cycles since we're only talking partial cycling. But you're right about longevity when used this way. It would apply to the 85kWh battery of the Model S too I think - let's say you could drive the car 99% of the time plugged in (think super-long extention cord): then I don't think you'd see much degradation after several hundred thousand kilometres. It's high SOC, low SOC, elevated temperature especially at high SOC, high charge rate, high discharge rate that degrades the battery.

    With regards to the OP: this announcement has little value until they can show a commercial product. By that time Tesla will have something better :)
     
  7. VolkerP

    VolkerP EU Model S P-37

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    All hybrid batteries are designed to take a lot of cycling. Depleting it for an all-electric range of 2 km at urban speeds (let's say 30 kph) means some 15C discharge rate.
    But the chemistry has low energy density and quite high weight. It can't be scaled up 250 times to give the Tesla Model S range of 500km and still fit inside a car's size and weight constraints.

    In other words, it is still not possible to build a long range EV with these. LiFePO4 energy density is known to be orders of magnitude worse than the Panasonic cells used by Tesla.

    Who wants to drive an EV that's empty in half an hour? This makes sense for hybrids but not for pure BEV like Tesla.

    BTW this belongs in the batteries subforum: Battery Discussion
     

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