Sulfur Polymers Could Enable Long-Lasting, High-Capacity Batteries

MTorrice writes "Lithium-sulfur batteries promise to store four to five times as much energy as today's best lithium-ion batteries. But their short lifetimes have stood in the way of their commercialization. Now researchers demonstrate that a sulfur-based polymer could be the solution for lightweight, inexpensive batteries that store large amounts of energy. Battery electrodes made from the material have one of the highest energy-storage capacities ever reported" Litihium Ion batteries should maintain capacity for about 1000 cycles, whereas Lithium-sulfur batteries traditionally went kaput after about 100. But it looks like they are getting pretty close to something feasible, from the article: "The best performing copolymer consisted of 90% sulfur by mass. Batteries using this copolymer had an initial storage capacity of 1,225 mAh per gram of material. After 100 charge-discharge cycles, the capacity dropped to 1,005 mAh/g, and after 500 cycles it fell to about 635 mAh/g. In comparison, a lithium-ion battery typically starts out with a storage capacity of 200 mAh/g but maintains it for the life of the battery, Pyun says."

Re:Still a ways to go

[Gravis Zero]

I saw an interesting graph in Aviation Week some time ago about the energy density of batteries versus the same mass of hydrocarbon fuel.

the problem with that comparison is that it considers that the engines and motors will have the same efficiency which is not true at all. hypothetically, if your motor is four times as efficient as an engine but your battery has only half the energy storage of the engine's fuel, the motor is still going to run twice as long as the engine.

it's systems, not components that matter.

Re:Still a ways to go...until we get where?

[skids]

Ah, so we're throwing the aircraft through the air with the power of pixie dust and unicorn farts.

Aircraft engines are a red herring here, since the target of these batteries is automotive. But for what it's worth, jet turbines also only convert a portion of the fuel's chemical energy into kinetic energy. Combustion efficiency is 90%+, but cycle efficiency in turbojet and similar is nearer to 30%. [wikipedia.org]

For automotive, in contrast to ICE+drivetrain at about 25%, shows average values of about 36% [wikipedia.org] and this is in part due to the efficiency of electric drive trains and in part due to the efficiency of the fuel cell process, but of course externals in the fuel production.

Batteries win hands down against both of those options for efficiency, with externals excluded, so the same amount of energy in a battery is worth more miles than the equivalent amount of chemically stored energy in gasoline once it is onboard.

Re:Still a ways to go...until we get where?

[beanpoppa]

At the risk of sounding 'Applely', Think different. Right now, I have to stop to 'recharge' my ICE car for 5-10 minutes, once a week. That's, on average, about 6 hours a year I wait for my car to 'recharge'. If I had an electric car, I would be plugging it in every night. For most weeks of my commuting year, it would eliminate any time waiting at the gas pump.

Re:Many exciting developments in batteries

[bluefoxlucid]

The varying lifetime is less important than people think. If you have a 300 mile range electric vehicle battery that can handle 1,000 charges and you replace it with a 3,000 mile range battery that can handle 100 charges, you can still go 300,000 miles. It just turns out you can go 3000 miles in one trip.