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(The Register)   Researchers cross sodium-ion battery with pine tree, create something you'll be able to plug Christmas lights into   (theregister.co.uk) divider line 10
    More: Interesting, Christmas lights, lithium batteries, anodes, electrolytes, pines, cathodes, cellulose, carbon nanotubes  
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1359 clicks; posted to Geek » on 08 Jul 2013 at 8:32 AM (1 year ago)   |  Favorite    |   share:  Share on Twitter share via Email Share on Facebook   more»



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2013-07-08 08:36:10 AM  
can they make a low sodium battery please i'm watching my weight
 
2013-07-08 09:24:06 AM  
A salt in battery?  That sounds criminal.
 
2013-07-08 09:34:16 AM  
145 mAH/g @ 400 cycles?

someone please correct me if I am wrong but assuming it has a similar voltage to lithium ion batteries (3.2 volts or so), wouldn't the energy density of the battery after 400 cycles be ((.145AH x 3.2V) x 1000) or 464 watt-hours/kg?

Thats still something like twice the performance of the best lithium-ion batteries out there, which also have a relatively short 400-1200 cycle lifespan. Twice the performance AFTER 400 cycles. Its original capacity would be just over a kilowatt-hour/kg.

Someone please tell me I've overlooked something crucial here, messed up my math, or the Scientists protoypes are just ridiculously energy dense due to having no other components...

A quick online search for more info on sodium ion batteries puts their voltage at a higher 3.6V, though most batteries had a more modest 80-106 mAh/g rating, and they degraded to something like 60mAh/g after only 20 cycles. 60mAh/g at 3.6 volts is still neck and neck with some of the better lithium ion batteries out there...

Maybe sodium ion batteries are just that much better than lithium batteries on a basic level as far as energy density goes.


The researchers energy densities are fairly insane though still. 4x top of the line lithium ion battery density on first charge... 2x after 400 cycles, which is near the end of the life for many lithium ion batteries...


Hopefully someone more qualified than I am can shed more light on this mystery for me....
 
2013-07-08 10:01:27 AM  

RecentGrad: 145 mAH/g @ 400 cycles?


I couldn't find much more info, but apparently the sodium ion batteries take much longer to charge, making them ineffective for consumer electronics.  I was trying to find a picture or the dimensions of the experimental battery but couldn't find anything.  I imagine it is also much larger, using more material, than the lithium ion batteries you are comparing them to.
 
2013-07-08 10:24:23 AM  
I farking love this field.
 
2013-07-08 11:02:27 AM  
Since Li batteries are used in mobile meth labs, does this mean that pine scent is the next drug dog skill or do Na batteries just not work in that process?
 
2013-07-08 11:24:44 AM  
[I_bet_the_scientists_did_this.jpg]
 
2013-07-08 11:53:00 AM  

RecentGrad: Hopefully someone more qualified than I am can shed more light on this mystery for me....


I can't read the paper without buying it, but presumably that number is the anode energy density, which is always significantly higher than the cell energy density.
 
2013-07-08 12:40:16 PM  

Hollie Maea: RecentGrad: Hopefully someone more qualified than I am can shed more light on this mystery for me....

I can't read the paper without buying it, but presumably that number is the anode energy density, which is always significantly higher than the cell energy density.


Found an abstract.  These numbers are in fact anode densities.
http://pubs.acs.org/doi/ipdf/10.1021/nl400998t
 Since cathodes are generally less dense than anodes, immediately cut that number in half or worse.  Add electrolyte and casing and you are down to pretty pedestrian values.  Also, losing 50% capacity in 400 cycles isn't really too much to crow about.  The latest Lithium Iron Phosphate batteries are good for 2000-3000 cycles to 80% of initial capacity--and that's if you don't treat them well.  Stay away from the top and bottom margins, and they have been tested for over 10,000 cycles to 80%.  Don't get me wrong--I'm glad people are working on this, but they have a LONG way to go.  Maybe they will get there and have a slightly cheaper battery that's good for stationary applications.  Ultimately though, these crazy electrodes and electrolytes that are being studied are going to be used to make better lithium batteries--for example a chemistry that suffers from a similar cycle degradation (Lithium Sulfur) really will be a game changer if they can make some modest progress on that front.  Ultimately, Lithium isn't really what makes batteries expensive, and despite what you read in the news it is not particularly rare.
 
2013-07-08 02:06:17 PM  
IIRC lithium in bulk is like 100$ a kilogram. that's pretty expensive, and a very significant portion of the battery cost.
 
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