Sand-Based Anode Triples Lithium-Ion Battery Performance

Zothecula (1870348) writes "Conventional lithium-ion batteries rely on anodes made of graphite, but it is widely believed that the performance of this material has reached its zenith, prompting researchers to look at possible replacements. Much of the focus has been on nanoscale silicon, but it remains difficult to produce in large quantities and usually degrades quickly. Researchers at the University of California, Riverside have overcome these problems by developing a lithium-ion battery anode using sand."

Comments

Little Bit of History Repeating.

[Anonymous Coward]

I love the way that at the end of TFA there are links to pretty much the exact same story dating from 2013, 2012, 2009 and 2003.

Re:Little Bit of History Repeating.

[Anonymous Coward]

The anomaly was caused by the submitter using one of the early prototype batteries to power his computer.

Since then I've discovered that the battery actually steals electricity from the future, and the original submission is stuck in a time loop.

Signed,
Emmett Brown

p.s. Great Scott!

Re:Little Bit of History Repeating.

[Rei]

Commercial li-ion battery energy densities have continued to improve during that time period, including the commercial introduction of cells with silicon anodes. Of course, silicon anodes are a new tech, so there's a great deal of room for improvement, which probably won't come close to "maxing out" for a decade or more.

Of course, that said, this article is your typical fluff piece following the guidelines of fluff science reporting.

1. Present an oversimplified version of one technology challenge that may or may not address the biggest issue and certainly doesn't address all of them - but don't mention that.
2. Introduce an outside-the-establishment loner with a passion - or at least someone you can try to present as "outside the establishment" and glaze over anyone who helped him.
3. Loner gets a "vision" based on some everyday activity
4. Present their solution and make it out to be a huge revolution that will certainly solve all our problems - if they can only get corporate backing / funding!

I think these sort of articles hurt the image of science because people read them, think "OMG, all our problems are solved!", then when everything's not solved afterward, fail to trust science in the future. For example, in this case, the most important element to improve is the cathode, not the anode. And cathode improvements are less common and usually less major than anode improvements. There's also tons of different anode improvements out there in various stages of research. Pretty much all of the silicon ones get way better than graphite or amorphous carbon.

That doesn't mean that this isnt an important paper - actually, from looking at it, it looks pretty good. It's just not "all that".

BTW, anyone know how credible this journal is? I see it's hosted on Nature.com but not part of Nature, and I tried to find an impact rating for it but couldn't.

Re:Little Bit of History Repeating.

[wooferhound]

Sand in my batteries . . . Next they will try and convince me that Sand will improve the performance of my computers brain ?

Correct me if I'm wrong, but...

[ThreeGigs]

Looking at the actual research paper, all I see is improved durability, _not_ increased capacity. Yet the article claims you'd only need to "charge every three days instead of every day".

Am I reading the research paper wrong or is everyone else?

Re:Correct me if I'm wrong, but...

[Rei]

1024 mAhg1 is excellent capacity even vs. brand new graphite or amorphous carbon, about 3x as much as graphite's maximum. Silicon's theoretical max is 8-10x that of graphite, but the main problem with it is durability, it tends to tear itself apart on loading. There are silicon anodes in some newer li-ion cells on the market, but the tech is in its infancy.

That said, the real papers you want to be on the lookout for are cathode improvements, there's a lot more potential for volume/mass reduction there than in the anode. But it seems to be a more difficult challenge. Getting a 3x improvement in anode density is absolutely not the same a getting a 3x improvement in battery life.

Launch date

[kingsaj2]

Can we have announcements when these products are actually launched and are in use. Every month we hear of some new battery tech that will revolutionise everything in 5+ years time.

Re:Launch date

[rtb61]

Here is the rub, as they continually improve batteries committing to a production line becomes harder. Getting say fifteen years of life out of a battery production line becomes impossible with batteries improving every year and your production line being way behind latest technology.

So there are certain levels in development where sufficient gain is made to commit to a production line even though the batteries will be out of date or the production line is based around a much reduced life with substantial impact on battery price. This is aided by government subsidises, making it possible to initiate a battery production line with less than optimal outcomes.

Of course producing batteries builds the infrastructure and pays for more development. It is getting pretty obvious though that full scale electric vehicles are no longer that far off as battery technology continues to develop and companies can commit to major battery production lines with a required life to pay for that production line.

That said...

[Rei]

... the greater your capacity, the less cycle life matters. If you want an EV that battery that will run a 250Wh/mi vehicle for an average 20 miles a day for 15 years, then you want it to cycle through about 30MWh. If you use a 100 mile (25kWh) battery pack, then that's 1100 cycles. If you use a 200 mile (50kWh) battery pack, then that's 550 cycles. If you use a 400 mile (100kWh) battery pack, then that's a mere 275 cycles. Actually, the improvement is even better than that in the real world, because the greater your capacity vs. how far you're actually driving, the more you can cycle the cells through a less destructive state of charge range rather than doing deep discharges.

A lot of people picture battery packs in EVs backwards, they think that things like hybrids stress the packs the least, PHEVs moderately, and EVs the worst. But it's reversed. If you look at how big hybrid packs are vs. how much electric range they hold, you'll see that they're disproportionately large, even after you factor in any differences in Wh/kg. The reason is that because hybrid packs get cycled so much, they have to keep the cycling in a very narrow state of charge range, only allowing shallow discharges. So if you only have a narrow discharge range, you have to make your pack bigger to make up for it. EVs can discharge through much more of their pack because they need fewer total cycles and only rarely go down toward the lower end of their allowable discharge range. Some EVs also let you limit the max that your pack charges up to to further extend lifespan (it's usually destructive both to use the very top end and the bottom end of the discharge range).

Re:That said...

[swillden]

Some EVs also let you limit the max that your pack charges up to to further extend lifespan (it's usually destructive both to use the very top end and the bottom end of the discharge range).

That is the theory, but real-world experience with the world's most successful EV (Nissan LEAF) isn't bearing it out. There doesn't appear to be any significant benefit to limiting charging to the 80% level. What is proving to matter, a lot, is temperature. The risks of very cold temperatures are so extreme that the cars have built-in battery heaters (powered by the batteries, obviously) to protect against them, so in practice cold just reduces range, but hot temperatures seriously impact battery longevity.

Another theoretically-predicted battery-killer that is not showing real-world degradation is quick charging. I believe Nissan has even stopped telling people they should limit the amount of level 3 charging they do.

Excellent points about larger capacity batteries needing to survive fewer cycles, though.

Sand!

[PPH]

Our energy supply is still at the mercy of those damned Arabs!