The Battery technology thread - How will EVs be powered?

[speculawyer]

The best info indicates that the Aptera will be powered by some type of 10Kwh battery which uses some type of Lithium-Ion chemistry. That is about all that is known.

This thread is to discuss battery technology since it is clearly the Achilles heel of the entire EV industry. The cost, maintenance issues, durability, and energy density have largely prevented the EV industry from taking off. Will these problems be solved at all? Or is it just a long wait until oil/gas prices are so high that EV technology looks interesting by default.

Here is a series of articles about one guy's views on battery technology . . . he seems to think that lead-acid will have a revival. I doubt it.
http://seekingalpha.com/author/john-...rticles/latest

[KarenRei]

Current lithium tech is already pretty darn good, apart from price, and it has a long way to advance. Graphite holds a tenth as much lithium as silicon (and tin holds nearly as much as silicon), while there are several ways that should be able to get at least 2x as much in the cathodes, possibly more. My brief calculations suggest that a battery pack energy density of around 340Wh/kg and a 90% efficient drivetrain with 70kg for the inverter/charger/motor/associated wiring/etc will give you about the same range as a gasoline car that's 20% efficient, has a 12 gallon tank (35kg of gasoline) and has a gas tank + engine + transmission + emissions controls + PbA battery + fluids + etc, etc mass of 315kg. 340Wh/kg definitely seems like an achievable target for li-ion packs -- and even if you don't get that high, so what if your car is a couple hundred kilograms heavier and you have to design in a few extra cubic feet of space for the pack? Also, getting rid of the cobalt or increasing the energy density, plus mass production, makes prices in the $0.10-$0.30/Wh range look quite achievable. Extremely high power rapid chargers are already in the same price range as the per-pump cost of a gas station, and charge times shouldn't be an issue with them.

Oh, and the cake is a lie.

[zguitar71]

A123 Systems produces Nano-phosphate Lithium batteries that, according to them, cannot catch on fire and hold up to 10x the charge of other lithium batteries (most people are getting around 3x). They are being used in Dewalt rechargeable 18 and 36 volt battery packs. There are videos on you tube that show how to take them apart use the individual cells for different applications. People have been using them for RC cars and stuff and ev racing motorcycles with great success. The downfall is the cost. The 36v battery packs contain 10 cells, 3.6v each @ around 2.2 amp hours. So quite a few packs are required to assemble the battery needs for a car in both series and parallel. The 6800 cells that the Tesla uses would cost around 60k that way and the cells cannot be bought retail yet. The current cost is around $10-16 per cell getting them the hard way. The bright side is the request from different manufactures for the A123 batteries is increasing and the cost are coming down. IMO it will not be very long before there are batteries that can compete with ice cars for power and range and not cost much more, probably something like 10 years or so if everything continues as is.

[IamIan]

Energy storage technology continues to move forward in small steps every year. There is always someone promising some massive leap forward. But it has never happened. Slow and steady things continue to improve.

Li has the 2nd best energy per unit weight and per unit volume which are the two highest priority items to vehicle energy storage. But still hasn't been able to show that they have beaten the shelf life losses. They are still very expensive.

NiMH has less energy per unit weight or unit volume than all but the worst Li batteries. But tends to cost less per kWh of battery. NiMH also does not have the shelf life issue Li still struggles with. NiMH with the newer LSD version no longer self discharge any faster than the Li batteries do. They remain as the middle ground between the venerable Lead Acid and the newer Li.

NiCd research kind of flat lined... It seems like 90+% of the Ni Battery research has all shifted to NiMH... while ~75% of all battery research now seems to be targeted toward Li.

Lead Acid continues to truck along. It is still the cheapest per kWh of battery. Minor improvements continue to trickle in year by year. It still has one of the lowest amounts of kWh energy per unit weight or volume. It remains a popular choice of the DIY EV Conversions & stationary applications.

Super / Ultra Capacitors currently have the lowest amount of kWh energy per unit weight and volume. They are also even more expensive than Li batteries. But Capacitors are the longest lived of all the options. They will last longer than the average human lives, even with constant cycling. They also provide the fastest rates for charging or discharging. They have the best cycle efficiency from what you put in compared to what you take out. research continues.

Fly-wheels are still a tiny fringe market. The fly wheels themselves store more energy than Li batteries. The required containment devices are still the killing feature of Fly-wheels. the containment weighs too much, is too expensive, etc..etc... Cost is prohibitive even higher than Ultra capacitors. The cycle energy is not any better than Li batteries. The peak surge power is only slightly better than Li , but not as good as capacitors. Still research continues.

Reversible fuel cells have very low kWh per cost , per pound, or per volume. The Cost is on par with Li. The weight and volume are on par with Lead Acid. Research continues to make the tiniest of improvements.

Nuclear cells are hands down the most expensive option of all. For Manufacture, maintenance, re-fueling, clean up from traffic accidents, disposal at the end of life; they are the most expensive of all choice in just about all ways. But they do have the highest potential of energy per unit weight or per unit volume. research is on-going.

[IamIan]

Originally Posted by zguitar71

A123 Systems produces Nano-phosphate Lithium batteries that, according to them, cannot catch on fire and hold up to 10x the charge of other lithium batteries

correction... A123 cells have high current rate / power densities.

They actually hold less energy than all but the worst of the other Li batteries. Modern NiMH cells are actually very close to what A123 cells can hold in terms of energy per unit weight or volume.


A123 ( 26650 ) has :
~209 Wh per L of volume
~108 Wh per kg of weight
As of ~1 year ago 0.5 Wh per $ spent

The CTA 12 Ah NiMH "D" cell on the market ~3 years ago has:
~276 Wh per L of volume
~90 Wh per kg of weight
As of ~1 year ago 1.53 Wh per $ spent

The Gaia HE-602050 Li Battery on the market ~3 years ago has:
~380 Wh per L of volume
~150 Wh per kg of weight
as of ~3 years ago ~0.54 Wh per $ spent

[KarenRei]

A123 Systems produces Nano-phosphate Lithium batteries that, according to them, cannot catch on fire and hold up to 10x the charge of other lithium batteries (most people are getting around 3x).

That's incorrect. They actually hold less energy than other li-ion batteries (~100Wh/kg instead of ~180Wh/kg). They have a much higher *power* density, however.

There are videos on you tube that show how to take them apart use the individual cells for different applications. People have been using them for RC cars and stuff and ev racing motorcycles with great success. The downfall is the cost. The 36v battery packs contain 10 cells, 3.6v each @ around 2.2 amp hours. So quite a few packs are required to assemble the battery needs for a car in both series and parallel.

At one point, that was the only way to get LiPs, but they're obtainable on the open market these days.

Li has the 2nd best energy per unit weight and per unit volume which are the two highest priority items to vehicle energy storage.

What are you picturing that's better? Zinc-air is more of a fuel cell than a battery, if that's what you're thinking of.

NiMH also does not have the shelf life issue Li still struggles with.

Traditional li-ion has significant shelf-life issues, but the more modern variants, especially the titanates, do not.

Fly-wheels are still a tiny fringe market. The fly wheels themselves store more energy than Li batteries.

Flywheel energy densities aren't very high. Flybrid's flywheel hybrid system, for example, is barely 20Wh/kg. They got about 300kW/kg power density.

Reversible fuel cells have very low kWh per cost , per pound, or per volume. The Cost is on par with Li. The weight and volume are on par with Lead Acid. Research continues to make the tiniest of improvements.

Price issue with nearly all fuel cells is not cost per kWh; it's cost per kW. Which is currently obscenely high -- in the case of non-regenerative PEMFCs, $10/W or so. It'd cost as much as a low-endcar to get a fuel cell stack only strong enough to power a blow dryer.

Nuclear ... But they do have the highest potential of energy per unit weight or per unit volume. research is on-going.

Thinking of betavoltaics, perhaps?

Honestly, I'd expect us to see solar powered cars covered in 60%+ efficient cells before we see nuclear powered cars. Betavoltaics, the safest small-scale nuclear power I'm aware of that works today, is incredibly low power and the cells degrade too fast. Still, it'd be neat

[speculawyer]

Originally Posted by KarenRei

Honestly, I'd expect us to see solar powered cars covered in 60%+ efficient cells before we see nuclear powered cars. Betavoltaics, the safest small-scale nuclear power I'm aware of that works today, is incredibly low power and the cells degrade too fast. Still, it'd be neat

RIP Ford Nucleon

http://en.wikipedia.org/wiki/Ford_Nucleon

[speculawyer]

Anyone have any comments on the various Sodium batteries? They are currently shipping (sort of) in the Th!nk City. They seem to required a bit of maintenance (heating, monitoring, etc.). But this article seems to indicate that sodium batteries may see decent price drops:
http://seekingalpha.com/article/1118...ore-it-can-run

[KarenRei]

Yeah... really shows the hubris of the nuclear age, doesn't it? "We'll stick a nuclear reactor in a device that gets into collisions all the time."

[KarenRei]

Originally Posted by speculawyer

Anyone have any comments on the various Sodium batteries? They are currently shipping (sort of) in the Th!nk City. They seem to required a bit of maintenance (heating, monitoring, etc.). But this article seems to indicate that sodium batteries may see decent price drops:
http://seekingalpha.com/article/1118...ore-it-can-run

Pros: Good energy density, pretty solid lifespan, nontoxic, efficient (apart from energy wasted on heating), moderately priced with potential to drop, no worries about low-temp operation (since heating is inherent in the battery).

Cons: Awful power density, energy wasted on heating except at high power draw, has all kinds of storage issues due to having to maintain the heating or lose most of your charge.