Skeptical toolkit for new battery technology:1: Haste is a pain
: shoving energy quickly into a battery requires high charging currents. This is an unavoidable physical fact, and independent whether its Li-Ion of a supercapacitor.
Quick example: A typical smartphone battery has a capacity of about 3000mAh, which means it can deliver 3 Amps (at 3.6V) for one hour, or 300mA for 10 hours, or 100mA for 30 hours.
To charge such battery capacity in just 30 seconds it would require a whopping current of (120*3000mAh =) 360Amps. That's impossible to deliver safely into a thin smartphone. High currents are a bitch, and would take fist-sized connectors with 9-gauge (3.2mm diameter) copper wire. And it would take a power supply rated at at least 1300Watt, roughly 270 times stronger than the current adapter or ~23x as large as the charger of a MacBook laptop.
So a 30 seconds charge of a cell phone supercapacitor ain't going to happen, irrespective of the battery technology. Even a 10 minute charge will be a challenge to pull off. The amount of energy is too high for the amount of time.
For the same reason super fast EV charging is difficult. The Nissan Leaf EV has a 20kWh battery capacity which gives it a range of about 72 miles. To deliver that energy in one minute would require a whopping (20Kx60=) 1,200,000Watt, more than megawatt!. Currents would be at insane (1.2MW/370V=) ~3,250 Amps. For comparison, here are realistic charge speeds:
2: Haste is waste
- 110V/20A wall plug (2.2kW) ~4 miles/hour
- 220V/30A L2 plug (4.6kW) ~15 miles/hour
- Tesla DC Supercharger (90kW) ~300 miles/hour
- Gasoline fill-up: ~3600 miles/hour, thanks to the enormous energy density in gasoline
. About 15% of the charging energy is lost with slow charging. This waste generally goes up with higher charge speeds. The waste comes out as heat, requiring special cooling hardware. 3: Self-Discharge
is the amount of energy lost over time while not using the battery. Non-rechargable batteries lose ~0.3% of charge per month, Li-Ion batteries about 5% per month, but most supercapacitors lose about 50% per month. 4: Discharge profile
The output voltage of a supercapacitor goes down linearly with its state-of-charge. So at 20% capacity only 20% of the initial voltage is left. That poses a huge challenge for electronics, as it is designed for a narrow voltage range. A conventional Li-Ion battery still has over 80% of its initial voltage left at 20% capacity.
More on supercapacitors: http://batteryuniversity.com/learn/article/whats_the_role_of_the_supercapacitor