Scientists invent wafer-thin plastic that can store electricity , page 1
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reply posted on 6-2-2010 @ 12:25 PM by LeeTheDestroyer
reply to post by minkey53


sure does look like a capacitor....but a capacitor that can release its charge over a 20 minute period of time is a pretty interesting thing, which could have lots of uses.


reply posted on 7-2-2010 @ 05:40 PM by mdiinican
reply to post by LeeTheDestroyer


Capacitors can release their charge over as long a period as you want them to, the just don't have the energy density of a battery, so everyone uses batteries, not capacitors for power.

According to Wikipedia, the highest energy density ultra-capacitor on the market has an energy density of 30 watt hours per kilogram, or .108 MJ/kg. that's roughly comparable to old zinc-acid batteries from the 50s, or about 1/10th as much as modern lithium batteries.

this new technology isn't even an ultracapacitor, so it's energy density will probably be about 1000 times less.

For cheap applications, I'm pretty sure there's printable batteries now, so there are still thin power sources.


reply posted on 7-2-2010 @ 11:31 PM by LightFantastic
Originally posted by mdiinican
reply to post by LeeTheDestroyer

Capacitors can release their charge over as long a period as you want them to, the just don't have the energy density of a battery, so everyone uses batteries, not capacitors for power.

For cheap applications, I'm pretty sure there's printable batteries now, so there are still thin power sources.


The length of time a cap can release its charge is limited by its leakage.

There are also lithium polymer batteries available which can be very thin and have a high energy density.


reply posted on 8-2-2010 @ 12:43 PM by mdiinican
reply to post by LightFantastic


That's true, but capacitor leakage is usually pretty slow, like discharging an ideal capacitor over a few tens or hundreds of megaohms. Most rechargeable batteries also lose their charge over time. Over the charge cycle of a device like a phone or media player, neither effect really matters. It only really comes up for things that need to sit around charged for months at a time.

capacitors would be nice because they can be charged extremely quickly compared to batteries. The problem is you need at least 10 times the weight in ultra-capacitors to equal the same energy storage in batteries. (or about 10,000 times the weight of the same energy in gasoline)


reply posted on 9-2-2010 @ 12:54 AM by LightFantastic
reply to post by mdiinican

Generally available ultra/supercaps lose between 1% and 4% of the stored energy per day which is worse than a few tens megohms but as you say it doesn't really matter in many applications if you aren't too worried about efficiency. Other capacitor types are as you say but they aren't useful for bulk energy storage.

Ultracaps are useful for reducing the transient impedance of a battery however and prevent overheating and electrode damage.

I wonder what effect having lots of fast charge devices would have on our current electrical grid?



[edit on 9/2/2010 by LightFantastic]
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