Superior Anode For Lithium-Ion Batteries Developed 77
RogerRoast writes "The anode is a critical component for storing energy in lithium-ion batteries. The Berkeley Lab (D.O.E) has designed a new kind of anode that can absorb eight times the lithium of current designs, and has maintained its greatly increased energy capacity after over a year of testing and many hundreds of charge-discharge cycles. According to the research published in Advanced Materials they used a tailored polymer that conducts electricity and binds closely to lithium-storing silicon particles, even as they expand to more than three times their volume during charging and then shrink again during discharge."
Re:Subscription access only... (Score:4, Interesting)
Energy capacity (assuming constant voltage) is linear with stored charge.. stored charge is linear with quantity of active species, which is going up by a factor of 8, so I'd guess about 8 times.
Voltage is never constant under high discharge rates... lead acid "car" batteries are famous for covering their plates temporarily with gas (h2) and all batteries dump some fraction of their capacity into their internal resistance. For a good example try pulling 10 amps out of a giant deep cycle marine battery, then outta a nicad C size cell, then outta a pre-alkaline, pre-heavy duty zinc C size cell (think radio shack battery of the month club red battery).
expand to more than three times their volume during charging and then shrink again during discharge
Well, that's fairly terrifying word choice to anyone who did extreme stuff with prior battery techs. Expanding lead acid cell means the vent is clogged and you're about to get a large dose of flammable H2, corrosive electrolyte, and splintering plastic. Expanding lithium means its about to go kaboom. "Expand" is not a cool choice of words around battery people. Call it "volumetrically challenged" or something.
Re:Jaded (Score:2, Interesting)
Not gonna happen any time soon. The energy density (per unit volume) of alkaline long-life cells is about 50% higher than any other viable technology we have available. It seems unlikely anything is going to revolutionise this technology. Almost all current research is targeted at improving lithium cells, which are the next best (lower density than NiMH, but that technology has severe limitations on longevity that are not going to go away). Lithium is better in terms of density per mass, but what it absolutely cannot give you is a longer-lasting battery in the same physical format as an alkaline cell.
What we might hopefully see in the near future is a lightweight battery that can survive many thousands of charge cycles (LiFePO4 is the best in this respect with reasonable energy density, but it still lacks in density compared to Li-ion technologies, so there is potential to improve these to match and get a better battery). Unfortunately, they're still talking in terms of hundreds of cycles here.
To make true electric vehicles a reality (which is IMO the most important target of battery research right now) what we need is a battery that will last >2000 cycles and carries >200Wh/kg. The technology here looks like it might more than exceed these energy density requirements[1] but with only a 650 cycle lifetime it would probably be too expensive for day-to-day use. We might see something that meets these targets in the future, but it isn't here yet.
[1]: the abstract of the paper doesn't mention cell voltage and describes density in terms of milliamp-hours, which leaves you having to guess about plausible voltages, but we could be looking at 400Wh/kg or more here, so similar to Li-S batteries but without the very low lifespan associated with them.
Re:Subscription access only... (Score:5, Interesting)
I'd guess about 8 times.
If that's true, and even if it only works out to six times in production then it almost solves the car battery problem. We can get about 100 miles with existing batteries and 600 miles is about as far as a normal person would want to drive in a day (ie. average 60mph for ten hours).
(I say "almost" because of the following posts...)
Like more efficient solar panels (Score:5, Interesting)
I expect that the reason for this is quite sinister - Li-Ion batteries are used to enforce planned obsolescense, which is why standard cells are often packed into an overpriced proprietary plastic casing before sale. Manufacturers of consumer electronics don't want batteries that are still good after thousands of cycles. Apple also deserves a mention for pioneering the idea of packing the battery into the hard to open case of the phone/laptop itself, forcing 99% of the people who own these products to buy a new one as soon as the battery dies.