[BrianG]

While this technology sounds very promising for certain applications, capacitors will never completely replace batteries. At least not without some serious changes in how the power is drawn from them.

A capacitor discharges in a logarithmic curve. Meaning, once a load is placed on the cap, it starts discharging immediately. At 1TC (time-constant), there is only 36.8% of the voltage remaining. After another TC, 36.8% of that voltage is remaining. And so on for 5 TC (at which the cap is considered discharged).

So, even if a 10,000,000uF (10F) 100v cap (which would be absolutely ginormous by the way) and is loaded with 10ohms, the TC is 100 seconds (TC=R*C). So, with 100v on the cap, that load would cause the voltage to drop to 36.8v in about 1.5 minutes (and current is dropping continually during this time) after just one TC. If the load "wants" 100v, the voltage on the cap is already unusable.

To get any kind of long-term usable voltage on a cap when loaded with anything more than an LED or two, it would have to be in the hundreds of farads, not micro-farads as they are usually rated, to keep the voltage during the first TC in a usable range. OK, so lets add in a switching PS device that would output a steady voltage regardless of the cap voltage (to a point of course). But even then, the ever-increasing load (as the PS draws more current to compensate for falling voltage) will just decrease the discharge time to something like 2TC total. So, using our 10F 100v cap example above, you could get maybe 3 minutes out of it instead of 1.5 minutes. Hardly seems worth it to me.

One of the articles about this technology does state the discharge and charge is more linear, so this would be a little different than the logarithmic curve of current cap technology, but still nowhere near similar to the relatively flat discharge curve of a battery.

No, I see these caps as supplemental devices that would be used along with batteries for larger-scale applications like EVs and the like. The caps would handle any extreme burst currents, so the battery would see more of a steady drain. The battery could then be designed to be more efficient at a more moderate discharge rating (no more 50C requirements) and smaller cells could be used as long as super-long runtimes aren't needed.

One of these articles states that you could charge a cellphone in seconds if powered from one of these super caps. Assuming these caps were hypothetically used with additional circuitry to power cellphones with a steady voltage supply, let's look at that for a second. A typical smart phone has around 2000mAh single cell battery. To charge that in 30 seconds, you would need a power supply capable of delivering around 240 AMPS at 5v. Hmm, yeah, I don't see myself rushing to hook up 2 gauge charging wires to my phone!

So, yeah, this technology does have merit (smaller size, simple/cheap to make, biodegradable, etc). But many of these "breakthroughs" tend to be over-hyped without much technical detail. To hear them talk about it, it is THE answer to all our woes.

By the way, exactly how did they make a graphene layer using a "standard DVD burner"?? In the video, they put the graphite solution on a DVD, put it in the tray, and out pops a graphene disc. I really don't think it's a standard DVD burner because; How does the disc spin at all without whipping the solution off the disc? OK, so maybe they used some custom software to spin the DVD reeeaaaalllly slow. But, how are they "burning" the disc when the laser is facing the underside of the disc? They put the solution-covered DVD facing up (duh, obviously), so is the laser burning through the disc before it hits the solution? Or did they mod the player so the laser is on top (which means it is not a "standard" burner).