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She won the $50,000 Intel Foundation Young Scientist Award

A high school student from California has created a way to charge cell phones completely in just 20-30 seconds. 

Eesha Khare, 18, of Saratoga, California, recently won the $50,000 Intel Foundation Young Scientist Award for her fast-charging device. 

The device uses an improved supercapacitor that can store a lot of energy into a small space using a nanorod electrode. It is capable of 10,000 charge-recharge cycles and can fully charge a cell phone in 20-30 seconds. 

Traditional chargers typically take hours to achieve a full charge, and are capable of only 1,000 cycles for rechargeable batteries.


Khare said her supercapacitor has been used to power an LED, and sees her invention being placed in cell phones in the future.

"It is also flexible, so it can be used in rollup displays and clothing and fabric," Khare said. "It has a lot of different applications and advantages over batteries in that sense."

This definitely isn't the first time a high school student has come up with a brilliant invention in recent years. Just last year, 15-year-old Jack Andraka invented a new pancreatic cancer test that earned him the $75,000 prize from another Intel-sponsored fair. 

Source: NBC News



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RE: Paper
By EricMartello on 5/20/2013 1:12:06 PM , Rating: 2
quote:
That's not correct. Generally, batteries that are more energy dense for a given chemistry have much slower charge and discharge rates. Compare the Panasonic UR18650ZTA and the UR18650SAX.


Yes, they would, if you think of the batteries as buckets the bigger the bucket the longer it takes to fill or empty it using a fixed flow of water. It's not necessarily that they charge or discharge at different rates, it's just that a larger capacity takes longer to fill and lasts longer under load.

quote:
Same manufacturer and basic chemistry, but one can be discharged at 8C without affecting the final capacity much but another starts to quickly lose capacity even discharging at 1C.


One battery is 1350 mAH and the other is 3000 mAH; the larger capacity battery does not experience as much of a voltage drop under load as the smaller battery does, but that doesn't really counter what I said.

All I said is that you can charge any modern rechargeable battery at 1C, with the implication being that it is safe to do so. You will not "lose capacity" but your battery may not be suited to a high-current application.

Some batteries do a better job of maintaining their nominal voltage rating under load than others. Certain batteries can be damaged if you let their voltage get too low - but that is beside the point.

In general, a higher capacity battery will have higher tolerances for current in both charging and discharging cycles, but 1C is going to be a safe charge or discharge rate and your links support that statement.

quote:
The extreme example of this are high capacity rechargeable lithium coin cells, where a 3032 sized cell can have a 100mAh capacity, but won't be able to charge or discharge more than 1mA.


If the battery you were referring to is the only one of its kind them maybe you'd be right, but check this link below:

http://www.eemb.com/pdf/Li-ion/LIR3032.pdf

Note the "max current" for charge and discharge...but also consider that an application where 100 mAH @ 3V is sufficient would typically not incur high current draw nor would it require a rapid charging cycle.


RE: Paper
By MrTeal on 5/20/2013 4:38:43 PM , Rating: 2
quote:
Yes, they would, if you think of the batteries as buckets the bigger the bucket the longer it takes to fill or empty it using a fixed flow of water. It's not necessarily that they charge or discharge at different rates, it's just that a larger capacity takes longer to fill and lasts longer under load.

You're missing the point, the battery makers tailor the geometry of the battery to optimize for high current draw or high capacity.

quote:
One battery is 1350 mAH and the other is 3000 mAH; the larger capacity battery does not experience as much of a voltage drop under load as the smaller battery does, but that doesn't really counter what I said.

The larger capacity battery exhibits more voltage drop at high currents; a higher internal resistance is one of the trade-offs they make to get the higher capacity. Look at the discharge graphs, the high capacity ZTA has almost a 250mV drop between the 0.2C (0.6A) and the 1C rate (3A), while the low capacity SAX has only about a 100mV drop between the 0.2C (0.27A) and the 2C rate (2.7A). That's why if you pop open the battery pack of a Lithium power tool they all use high current, low capacity batteries instead of the really high capacity 18650s you can buy.

quote:
All I said is that you can charge any modern rechargeable battery at 1C, with the implication being that it is safe to do so. You will not "lose capacity" but your battery may not be suited to a high-current application.

That is the main point of what I'm getting at, not every modern battery can be charged at 1C. Standard Lithium Ion and LiPo ones you can, but there are modern chemistries used for different applications that can't be charged safely in an hour. It's a blanket statement that's not correct. You linked to a Lithium ion CR3032 that could be charged or discharged at 1C, I linked to one that cannot. Your blanket statement of "any modern rechargeable battery at 1C" is wrong.


RE: Paper
By EricMartello on 5/20/2013 6:43:46 PM , Rating: 2
quote:
You're missing the point, the battery makers tailor the geometry of the battery to optimize for high current draw or high capacity.


You disagreed with my generalized statement about 1C being a safe charge rate for modern rechargeable batteries, then you found some batteries that you thought would support your idea - but they did not.

You are right, 1C may not always be the OPTIMAL charge rate but it's safe to say that it's VIABLE.

quote:
Look at the discharge graphs, the high capacity ZTA has almost a 250mV drop between the 0.2C (0.6A) and the 1C rate (3A), while the low capacity SAX has only about a 100mV drop between the 0.2C (0.27A) and the 2C rate (2.7A).


Despite this, they both remain within 200 mV of their nominal rated voltages for at least half of their respective capacities...but this isn't what I was talking about.

At which point do you demonstrate where a 1C charge or discharge rate would be unsafe for either of these batteries? You seem to be hung up on the difference between 'optimal' and 'viable'.

quote:
You linked to a Lithium ion CR3032 that could be charged or discharged at 1C, I linked to one that cannot. Your blanket statement of "any modern rechargeable battery at 1C" is wrong.


I'd be willing to bet money that the one you linked to could be charged at 1C even if the spec sheet says no.

I would also say that what's commonly accepted by most people as a 'rechargeable battery' is not one of these niche button cells, rather it would be a cell phone, camera battery, AA or AAA type - all of which will charge and discharge safely at 1C.


RE: Paper
By MrTeal on 5/20/2013 7:59:45 PM , Rating: 2
quote:
I'd be willing to bet money that the one you linked to could be charged at 1C even if the spec sheet says no. I would also say that what's commonly accepted by most people as a 'rechargeable battery' is not one of these niche button cells, rather it would be a cell phone, camera battery, AA or AAA type - all of which will charge and discharge safely at 1C.


Actually, you're right there. I thought I'd inserted a link to the 100mAh coin cell I was talking about, but I obviously missed it.
http://www.panasonic.com/industrial/includes/pdf/P...
A button cell is hardly niche, there's billions of them made each year. They're just tailored to a different market, low self discharge and high capacity in a small size without a need for much current draw.

1C isn't some magic number, it's just that rather than choose to list energy storage in joules or some other unit, they settled on Ah. That many batteries can be charged in an hour or less doesn't grant some special physical significance to 1C.


RE: Paper
By EricMartello on 5/20/2013 11:24:53 PM , Rating: 2
quote:
A button cell is hardly niche, there's billions of them made each year. They're just tailored to a different market, low self discharge and high capacity in a small size without a need for much current draw.


What I meant by niche is that coin cells are not a common type. They're used in motherboards, clocks and compact devices that require something to preserve backup memory or whatever. Often they're installed by the factory and the consumer never worries about it until it dies, which can be years. A typical battery-powered device is going to use AA or AAA type batteries...but anyway I know what you were saying.

quote:
1C isn't some magic number, it's just that rather than choose to list energy storage in joules or some other unit, they settled on Ah. That many batteries can be charged in an hour or less doesn't grant some special physical significance to 1C.


EXACTLY! It is nothing special which is why I made my original statement in response to another poster's comment claiming that there was some wide discrepancy as to the typical charge/discharge rate for a battery.

The C in 1C refers to the capacity of a given battery in amp-hours, so 1C means 1 times capacity rating. You could have any number there to describe a particular charge or discharge current.


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