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Charge Your Cellphone In 20 Seconds (Eventually)
New submitter GoJays writes "An 18-year-old from Saratoga, California has won an international science fair for creating an energy storage device that can be fully juiced in 20 to 30 seconds. The fast-charging device is a so-called supercapacitor, a gizmo that can pack a lot of energy into a tiny space, charges quickly and holds its charge for a long time. What's more, it can last for 10,000 charge-recharge cycles, compared with 1,000 cycles for conventional rechargeable batteries, according to the inventor Eesha Khare." This one in particular has been used so far only to power an LED, rather than a phone or laptop, but I hope in a few years near-instant charging of portable electronics will be the norm as supercapacitors grow more common.
The one thing I like about supercapacitors (and non-super capacitors) is how quickly they can release all their energy. I can't wait to hold one up to my ear when it's embedded inside a device whose manufacture was outsourced to the lowest bidder!
did she have some new angle to the tech?
you can buy capacitor based battery replacements for cars.
world was created 5 seconds before this post as it is.
Sometimes I really hate "technology" reporting.
My phone battery has a capacity of 2.1Ah. To charge it in 20 seconds would require a current of 380 Amps. What kind of charger could safely supply that?
With the rapid adoption of portable electronics, Eesha Khare, 18, of Saratoga, California, recognized the crucial need for energy-efficient storage devices. She developed a tiny device that fits inside cell phone batteries, allowing them to fully charge within 20-30 seconds. Eesha’s invention also has potential applications for car batteries.
Will be doing some more Googling, but seriously, a link to the lab in which she worked or article/abstract published would be nice. Surely these are gifted kids, but I can't help but think the reporter really doesn't understand what she's done to write any thing more than a press release.
The only possible interpretation of any research whatever in the 'social sciences' is: some do, some don't
What a lot of these articles forget is the current requirements to charge something fast. Just because something can be charged fast doesn't mean you can do it.
Let's take a typical laptop battery of 70 watt hours. To charge it in one hour, you need a 70W power supply (more or less). Now let's charge that same battery - if we can - in 30 seconds, or 120th of the time. You'll need an 8.4kW charger to do that, which is going to be much larger and heavier than the laptop. In Britain where the mains electricity is 240 volts, you're going to need 35 amps to do that (typical household circuit is 13 amps, high power circuits for example ovens and tumble dryers are 30A). In the United States you'll need 70 amps.
OK, so you can charge slower (but still much faster than a conventional battery) but it's still going to require a large (heavy) power supply for your laptop if you want to make the charging speed significantly faster than current lithium ion batteries. You're either going to wind up lugging around a lot of extra weight with your portable machine, or you're going to need two chargers (more expense). The thing is, the times when you really wish you can charge a battery quickly are always times you're travelling and so won't have the large heavy charger with you!
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"supercapacitor, a gizmo that can pack a lot of energy into a tiny space, charges quickly and holds its charge for a long time"
Ah, Not really, no. Supercapacitor=1Mj/KG, pretty weak sauce relatively speaking.
Personally, I'm, holding out for a 'Doug Stanhope' phone with an ethanol fuel cell than 'runs on booze'.
"I bless every day that I continue to live, for every day is pure profit."
The rough version is there, it's called (quite missleadingly) a second battery plus a charger that can charge batteries externally. Been using that setup for years now and it can charge a phone in seconds, as long the phone has a changeable battery.
Guess companies might be able to fine tune it, e.g. make batteries easier to eject and insert, plus add a capacitor (a normal one, that keeps the phone live for say 30s), and you've got instant charging, today.
One problem with capacitors is the charge is stored a lot like water in a tank. As you use water the water level drops, in any capacitor, as you use it the voltage drops.
The governing equation is Q = 0.5 *C*V*V.
A single cell (in a battery of cells) is composed of two materials of different chemical states and they produce a constant voltage until one of the chemical states is depleted. Charging reverses this, again at a constant voltage. The charge and discharge voltages in a theoretically perfect cell are ~~ the same, in a real cell, resistance caused voltage drops and departures from irreversibility lead to differences in the charge discharge voltage. You must charge with a high voltage than you get on discharge.
A second problem, is the fact that a bulk material changes state in a cell, this inherently stores more charge than a capacitor, which is a surface layer of added charge. It is true that since the capacitor involves no change of state, that the life is more or less infinite, and because it is a monolayer of charge, you can charge and discharge at speeds limited only by the current limits of the wires.
The net result is the energy density of the best capacitors is barely as good as the worst batteries.
Battery graphs here http://tinyurl.com/autjb7l
Capacitor graphs here http://tinyurl.com/byqbdje
Direct comparisons here http://tinyurl.com/b9zwcdw
As long as you design a downstream voltage regulator to use the declining voltage to power your circuit at its required constant voltage, then ultracaps will find a niche in many pieces of equipment from Cars(as a peak acceleration source) to tiny items as the sole power
Interesting numbers. Just to compare, here's the energy densities of lithium-polymer batteries and super-capacitors, taking the values for best easily-available components I could find.
LiPo: 168 W.h/kg, 370 W.h/l
Super-cap: 5.1 W.h/kg, 6.6 W.h/l (I'm being slightly generous to the capacitor here, by counting the energy to discharge it to zero volts. In practice that last bit of energy will not be usable.)
The volumetric figures are most critical for phones, and in those terms batteries are 56x better than super-capacitors. So an improvement of 3x is interesting, but there's a lot more work to do.
Forgot to mention self-discharge rates: 0.007 C/day for LiPo batteries, and 0.08 C/day for super-caps (12x greater)
There were no affordable supercaps with leakage current low enough in the 1980's your memory is playing tricks on you. The standard means used was NiCad button-cell accumulators.
You are right about the age of supercaps though.
Most ACs are not even worth the keystrokes to insult them. Be generically insulted by this and ignored otherwise.
The article is brief on facts but i would bet my money she has just repeated the graphene super capacitor experiment done by and explained in detail by these guys https://www.youtube.com/watch?v=_oEFwyoWKXo all you need is a light scribe dvd player some grpahite oxide and a dielectric.
Rocket Surgeon.
The video references the issue with fast charging: Fast discharging.
People tend to forget that high quantities of stored energy have an inherent danger. Laptops catching fire because of lithium-ion battery failures are usually the only hazard that people tend to remember. To truly have a consumer safe device you want something that can be charged quickly but the maximum discharge rate is closer to a conventional battery.
The point is that when you exceed a certain speed of energy release the device starts resembling a bomb more then a battery. A wrench dropped across both posts of a car battery is spectacular enough in a very scary way (even before the battery actually explodes.) (And don't try this! An explosion can spray acid a LONG way.) A device that can discharge almost instantly is even more destructive. We obviously need to be able to store energy for so many different reasons but the method needs to remain safe even when handled in a completely negligent manner... like a consumer device.