More like 25% more than a NiMH per KW. The main problem with Li ions is their safety factor - they have a slight tendency to catch fire, particularly the high discharge rate ones. They do better in cold weather than any other battery tech, but..... I wouldn't want to own a car with them that is being used in Texas, Florida, Southern Cal. or Arizona. Another problem is, other than primary battery usage, Li ions don't have a history of being used in large projects like NASA, Military, etc., primarily because of their incindiary potential. And for this reason, the large 50KW+ batteries really haven't made it past research manufacturing levels. So there's no high volume manufacturing history which can give someone enough experience to using them on large projects, like cars. Don't get me wrong - we'd be able to carry around twice as much battery power in the same weight so I'm all for Li ion. Just not at the expense of providing a thermal barrier in the back of passenger seats. :lol:ElectricTroy said:Don't Lithium batteries cost ~$50,000???
They had similar problems with the NiMH in the Prius during the initial design stages...an advanced cooling system and design to prevent such fires in a collision can't be that difficult.billvon said:Some problems with current lithium-ion and li-polymer batteries are:
-Safety. If you short them, they can catch fire and burn, During some testing we did, the results were pretty dramatic - we got big jets of flame from the venting electrolyte. In an accident, where you could crush cells near the fuel tank, you could see some problems.
That's almost exactly what the charge regime is in the Prius Currently...-Charge regime. Ni-MH can accept current until they are full; li-ions need a voltage limited taper charge at the end to prevent cell damage. This means you can only get about 60% of their charge back into them via high rate charging (like regen braking.) This isn't as much of a problem for pure electrics.
Can't speak to that, but wonder if combining Super Capacitors...or even standard capacitors...would help with the rapid charge/discharge issue someone mentioned before as well as being able to deliver more instant current. I'd think the inverter could be improved to adapt to that as well. I do know that LiIon was given serious consideration back in '95 during the original design. There's also an interesting paper about the battery choice put out by Toyota that I have at home, but I'm at work at the moment. If I remember I'll post it here.-Max current. Li-ions have considerably higher specific energy (wh/kg) than ni-mh, but ni-mh can output a more current per kg. Thus a li-ion pack will give less performance (but more range) than a same-weight ni-mh pack.
I didn't think they were that much more, but can't swear to it.-Cost. They're currently about 2x the cost of ni-mh per wh.
Some of these may be overcome in future designs, of course. Li-ion is currently the best-density mature battery technology out there,
I don't believe they're supercaps, just standard....again, don't quote me on it.BIF said:Thanks for that article. Very informative. Am I to understand that my Prius' brakes already use supercap technology?
The problem we found is that if you puncture the case of a battery with a metal object (like a nail) you get:efusco said:They had similar problems with the NiMH in the Prius during the initial design stages...an advanced cooling system and design to prevent such fires in a collision can't be that difficult.
I think that's the next stage. Maxwell Labs has some D-cell-sized 350 farad caps now; they may drop in price enough to make hybrid cap banks doable. But if we ever get to that point, expect the caps to replace batteries completely. They don't wear out as quickly, they deliver orders of magnitude more instantaneous power, and they have no charge/discharge issues. The only problem right now is energy density, but that's less of an issue in a hybrid.efusco said:Can't speak to that, but wonder if combining Super Capacitors...or even standard capacitors...would help with the rapid charge/discharge issue someone mentioned before as well as being able to deliver more instant current.
Zinc-air is a cool technology, but the current large-cell designs I've seen are not yet rechargeable. You have to replace the battery. Some modern designs have easily replaceable plates; swap the plates out and you're ready to go again. Other designs allow you to suck out a zinc slurry and refill it with new slurry to "recharge" it; the slurry is then returned to a reprocessing plant where it's turned back into 'charged' slurry.drash said:There's another battery technology the Europeans (Saft) and Americans (Lawrence Berkeley National Lab - patent 5,441,820 & Electric Fuel Corp.) are persuing: zinc-air.
Yup, Zinc-air is cool but lithium-air is just awesome! Check out what Polyplus had to say about their new lithium aircell at a recent progress in LiIon conference:billvon said:Zinc-air is a cool technology.
It's not the lithium that's the problem - it's the other components of some lithium chemistries. For example, Saphion's LiIon cells which use quite an unusual chemistry (phosphate) are already landfill approved (see here). But I guess in practice the lithium itself is quite valuable so old batteries would end up being recycled.jg said:One issue not yet mentioned is that of disposal of old cells. Cells containing lithium are not so easy to deal with as say, NiMH.
