from the this-story-brought-to-you-by-Torchy-the-battery-boy dept.
Battery technology advances seem to come every other month, all of them seem to be the proverbial 5 years away. But by and large, these developments are simply nibbling around the edges of current battery technology, making minor improvements.
ArsTechnica reports that at the recent meeting of the American Association for the Advancement of Science, scientists explain that what is needed to make battery technology suitable for use in motor vehicles and grid storage is to triple capacity, AND cut price by nearly 70%. This would require raising the energy density of batteries from its present 200 W-hr/kg to about 600 W-hr/kg.
The way forward is to step out side the familiar battery chemistry we've been working with.
Electrodes play a key role in batteries in that they're where charge carriers—lithium in today's batteries—are held. Their ability to store lithium therefore becomes a key determinant of the storage density of a battery. Right now, carbon electrodes require six atoms of carbon for each lithium atom stored. Elements further down that column in the periodic table, like silicon and germanium, however, have a more complicated electronic structure, which can interact with more lithium atoms. As a result, you can store 4.4 lithium atoms for each silicon atom—a significant boost in capacity.
The article goes on to explain the issues with silicon. Lithium atoms cause silicon to expand, damaging the battery. Using, amorphous silicon beads and a polymer they've achieved 360 W-hr/kg version working in the lab. Still far short of the goal.
Jumping beyond silicon, the scientists explored Lithium-sulfur batteries, which have a theoretical capacity of 2,500 W-hr/kg. This would be an ideal material for electrodes, because it is cheap and plentiful. The article explains the struggle to get sulfur to remain where its needed. It has a nasty habit of forming polysulfides that can leak away from the electrode and undergo reactions elsewhere in the battery. A couple of different approaches to solving the wandering sulfur problem appear to be promising, yielding batteries in the lab that exhibit charge-discharge cycle counts comparable with today's lithium technology.
Are they ready for market yet? Of course not. In fact the researchers aren't even sure these chemistries are the right approach. Costs of production may still be too high. But the results are good enough to demonstrate that the major jumps in battery energy density are possible, and we may be able to blow right by the the goal of tripling energy density.
(Score: 0, Offtopic) by Anonymous Coward on Monday March 02 2015, @02:42AM
JavaScript is what drains my phone's battery the quickest. Less JavaScript, and more highly-optimized C and C++, would allow my phone to run for a lot longer than it currently can.
(Score: 1, Troll) by Anonymous Coward on Monday March 02 2015, @04:28AM
JavaScript doesn't have jack to do with electric cars and a number of other technologies that need a denser battery.
(Score: 0) by Anonymous Coward on Monday March 02 2015, @02:52AM
Excellent summary. I even clicked on the linked article.
(Score: 1) by BK on Monday March 02 2015, @03:54AM
...the path less traveled by. It could make the difference.
...but you HAVE heard of me.
(Score: 2) by Techwolf on Monday March 02 2015, @05:10AM
There is a current battery tech that can be use to replace car batteries and small solar farms. LiFePO4 (Lithium iron phosphate) Less weight, longer discharge curve, and the big one, 10x more charge/discharge cycles. Only downside, cost, but over the long term, much cheaper then lead acid.
(Score: 2) by bzipitidoo on Monday March 02 2015, @05:37AM
Batteries with 3 times the capacity won't help much without much better recharge times. We should live with the current glacial recharge rates, and wait 3 times as long for these batteries to recharge? Recharge time is so bad that in many cases for every minute spent traveling, it needs to recharge for 5 minutes! There are fast charging methods, but they require much higher voltage, shouldn't be used to charge to full as that will damage the battery, and shouldn't be used frequently as that shortens battery life. That leaves really only one option, a battery swap. But that too is not practical, as that takes far too much shelf space to hold all the charging batteries. If charge time is longer than discharge time, it's too easy to saturate a battery swap station, as they will be unable to to send out charged batteries as fast as discharged ones come in. That's totally unacceptable for any scenario involving continuous use, like for taxi cabs, pizza delivery, and of course, the road trip.
(Score: 0) by Anonymous Coward on Monday March 02 2015, @05:57AM
(Score: 1) by sorokin on Monday March 02 2015, @09:51AM
Some time ago I read this article: http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries [batteryuniversity.com]
It states that elevated charge voltages shorten battery life.
(Score: 0) by Anonymous Coward on Monday March 02 2015, @04:11PM
Why would you assume 3x the capacity mean 3x as long to charge? In reality, maximum charge rate generally scales linearly with capacity, so 3x the capacity means you can charge with 3x the current, which means a complete charge takes the same time.
Compare 18650 Li-ion cells, which when they started (or at least became popular in laptop batteries) were about 2Ah, and could be charged at 1A. Now available capacity has nearly doubled to 3.6Ah, and they can be charged at 1.8A.
Yes, and one simple answer to that is a higher capacity battery (whether by combining 5 similar batteries, or one magic battery from the future with 5x the energy density), and a higher-power charger to charge it. Now you get 5 minutes of travel, and recharge it in the same 5 minutes.
(Score: 2) by bzipitidoo on Monday March 02 2015, @05:44PM
More batteries, charge in parallel is a seemingly simple answer, yes. But that runs into other problems. That requires more wiring and electronics. A car that runs on several thousand rechargeable batteries of the AA size _could_ be built, but has not. Why? The wiring for all that could take up more space and add more weight than the batteries themselves.
Consider another simple gas saving idea on a conventional car: remove the alternator. Most combustion engine cars are good for about another 50 miles after an alternator failure. (I've done 25 miles in that situation. Would have been further but had to have headlights on because it happened just after sunset. Barely made it-- the headlights were real dim and the engine was sputtering when I crested the last hill and could see my destination. As I let up on the gas, the engine stalled, but I was able to roll downhill the rest of the way.) No alternator, and change to a larger deep cycle battery to get more range. This cuts fuel consumption by somewhere between 10% to 30%. So, why doesn't anyone do it? Even the most fanatic hypermilers pass on this one. One reason is that it takes hours to recharge the battery. A similar idea is to run electric pumps and fans for coolant circulation and fuel delivery on a separate battery, take that load off the engine. Again, not done because batteries can't deliver.
(Score: 1, Insightful) by Anonymous Coward on Monday March 02 2015, @07:22AM
Liquid fuel is best, easy to transport, store and fill.
Also, the mass of the battery itself is often pretty obscene.
Non fossil fuel chemical storage with a fuel cell seems like the optimal solution for vehicle use. Ammonia generated from renewable sources would be an excellent liquid fuel as it requires little compression to store.
Also, perhaps the tightening of the energy budget will force is to consider if maybe it's best not to move a tonne of metal for one person on their commute.
Viva la public transport (and the rationalization of city design to suit)
(Score: 3, Interesting) by carguy on Monday March 02 2015, @12:47PM
... maybe it's best not to move a tonne of metal for one person on their commute.
I'm guessing you are not in N. America? If we could get commuters down to one ton (2000 pounds) or tonne (1000 Kg) of car it would be nearly a 2:1 improvement. Many/most of the the fat SUVs in use here weigh more than two tons. With the most recent round of CAFE requirements (USA legislated fuel economy) weight savings has finally become necessary, prior to that there was no incentive to save weight.