Lithium explosiveness

bobbobwhite

Lithium has been commonly stated as explosive and/or flammable upon exposure to water. What does this mean for its use in electric/hybrid car batteries when there will be traffic crashes in rain that could damage the batteries and thus expose this element to water?

Thanks for all informed answers.

stewartcs

I suspect it means they should be well protected and insulated.

CS

bobbobwhite

I am suspect that mere protection of damaged lithium batteries from water such as rain or fire hoses is not going to be adequate, and lives may be lost in wrecks that expose lithium to water. As we saw with the Ford Pinto gas tank explosions 35 years ago, I am sure Ford thought those gas tanks were adequately protected but served as fiery bombs when hit causing many deaths.

We shall see what happens, but I will be glad when we get beyond the trendy era of the use of batteries for mass electricity storage for cars(physically limited anyway) and move on to regenerative, wind and solar sources, thereby making cars as close as possible to perpetual motion machines. It could be done. For example, cars could be made with 4 or even 6 wheels to a side primarily for regenerative purposes and the car could run simultaneously on the energy it produces at that moment and not have to rely on a huge bank of potentially dangerous lithium batteries. And, as batteries of all types are second only to disposable diapers in landfills, what of that potentially disasterous harm to the environment? I remain very skeptical of mass batteries for car usage.

Mech_Engineer

The lithium in a battery is no more dangerous than the tank of gasoline under the vehicle.

Do you have any concept of conservation of energy and efficiency losses? A car cannot "regenerate" energy, regenerative systems only recapture kinetic energy using a generator (and it isn't 100% efficient).

bobbobwhite

I can see I am not getting anywhere at all here as most of what I wrote is overlooked or misinterpreted. As I clearly wrote, regenerative energy is only one of the 3 potential ways I stated where energy can be produced/recovered to power a car. I did not say that it is the only way and would power a car exclusively, but the other two ways were overlooked in your response.

I also addressed the safety issue of certain unsafe gas tanks earlier. Maybe someone else can give their thoughts?

Mech_Engineer

The fact is I'm getting the smell of a perpetual motion machine from your post- let me explain by taking specific examples from your previous post:

I'm not sure there is anything "trendy" about batteries, but they are one option for storing energy in a vehicle. They aren't anywhere close to the storage capacity or convenience of a gas tank though. It's true they are somewhat hazardous with their component chemicals, but no more dangerous than many other things we take for granted in life every day.

This just throws up a huge red flag for me. Cars have a long way to go in efficiency, but we will never get close to perpetual motion. Losses to aerodynamic drag, friction, and drive system efficiencies will make sure of that.

"Regenerative sources" by definition cannot create energy, only recapture excess energy that would be thrown away (like a regenerative braking system, or exhaust steam turbine). I'm not sure how wind could power a car unless it was a wind farm generating electricity to be stored in a battery.

What you're describing here is an impossible machine. You cannot have wheels "generating electricity" for the car to drive. I think your are misinterpreting the application of the word "regenerative," not to mention conservation of energy.

berkeman

ME is doing a fine job, but okay, I'll offer a thought or two. Adding more wheels to try to recover energy does nothing. You need to have the energy in the first place to get you up to speed, and that has to come from someplace. It's not going to come from a windmill on the car ("wind"), and it's not going to come from solar panels on the car ("solar"). If you've seen the solar competition cars that run without batteries, you can see how specialized they are, and of course, they don't work too well at night or on cloudy days.

There is not enough energy available from the sun and wind to directly power a car, without a storage mechanism on the car. The only other way you could try to do it, would be to couple electrical energy into the car from coils in the road or something, but that would be a huge infrastructure undertaking, and it would carry its own safety hazards.

You are correct in saying that the batteries and electrical systems on hybrids and battery-powered cars are dangerous in vehicle accident situations. Firefighters and EMS workers are very aware of the new hazards that they face in accidents involving cars with big batteries and high-voltage motor systems.

hamster143

There's a big misconception here. Yes, metallic lithium reacts explosively when in contact with water, as does sodium and a number of other alkali metals. But there's no more metallic lithium in "lithium batteries" than there is metallic sodium in table salt. Automotive lithium batteries consist of a lithium compound cathode (usually lithium iron phosphate, LiFePO4, 5% lithium by weight) and a graphite anode.

As to the harm to the environment. Prius has been around for 10 years and yet there are essentially no dead Prius batteries in landfills. Do you know why? Reason #1: when you need to replace your Prius battery, you don't just throw your old one into the trash can and get a new one from your neighborhood Wal-Mart - you take it to your Toyota dealer, who then replaces the battery and recycles the old one. Reason #2: batteries are extremely long-lasting, Prius batteries can last the lifetime of the car. Reason #3: even if the car ends up in a junkyard, Toyota will pay a $200 bounty to the owner of the junkyard for the battery.

chayced

Although the lithium batteries may not react explosively with water they are far from 'safe'. Thermal runaway is a dangerous problem that is made worse by battery placement in hybrid and electric vehicles. In a gas automobile the gas tank is small, away from the driver and protected by as much of the car as possible. In an electric or hybrid the battery is large and by necessity placed wherever you can fit the cells. It's not unlikely for a catastrophic crash followed by firefighters applying water to cause cells to short and then you have a violent reaction on your hands.

Is this worse than gasoline? I don't know. I have never tried to put out a large lithium ion or lithium gel cell. I can say from the videos of thermal runaway that I don't want to be near any car that this happens to.

http://www.youtube.com/watch?v=jjAtBiTSsKY

NiMh batteries have their own problems. They can release large amounts of hydrogen

When it comes down to it any method of storing large amounts of energy is going to be inherently dangerous. When put in perspective, a liquid gasoline fire is really not that bad and easy to put out.

mheslep

Well put.

And that's for nickle hydride batteries. Lithium is not a heavy metal, and it costs 50x Ni. Count on it being recycled.

mheslep

No, safety depends on the compound not the element as hamster illustrated. LiCoO2, the compound used commonly in for the anode in cell phone and laptop batteries, can experience thermal runaway as the oxygen sneaks away from the weak cobalt bonds, and more oxygen escapes the higher the temperature. It's the O2 that encourages the fire. In LiFePO4, the compound being widely used by EVs, the oxygen is no going anywhere. That molecule will not let go of the oxygen even when hot.

Stanley514

Explosiveness of hydrocarbon fuel depends on kind.For example biodiesel seems to
be non-exposive.And even get spontaneus fire out of it is not very easy,I think.
It would be interesting to know about explosiveness of adsorbed fuels such as adsorbed
natural gas or hydrogen.I guess it's not very dangerous.We need to recognize that hydrocarbons is not only energy densiest but also one of the safest way to store energy.

mheslep

Safest as opposed to what?

Stanley514

"Safest as opposed to what?"

Biodiesel is apparently safer than:

1)Supercapacitors
2)Superconductive magnetic energy storage
3)Compressed air or hydro energy storage
4)Flywheels
5)Thermal molten energy storage
6)Any batteries which use alkali as anode or electrolyte
or may produce hydrogen or other gases in side reactions.

mheslep

Apparently? What metric are you using to make these comparisons? How many burning flywheels have been observed?

mheslep

Just saw this - of course biodiesel is explosive. See the MSDS on Biodiesel for specifics.
http://www.tsocorp.com/stellent/grou...sbiodiesel.pdf. You are likely confusing flammability with flash point. The flash point for bio-diesel is about double that of regular diesel, but both will explode given a spark when they reach that temperature point.

Stanley514

I don't know,but I never heard from somebody that cooking oil would explode on their
kitchen or become reason of fire.It would be difficult to set vegetable oil on fire with
help of spark or even matches.But it still good to be used in diesel engine where it does
"explode" under huge compression of diesel engine.