Moha,
I think you got it. (as far as conductivity)
Resistance is the inverse of conductivity.
Current dependes on resistance. (or conductivity)
When talking about changes in current as a result of changing wire construction, you almost have to say something like, "with voltage held constant" (I am being really picky there, I know)
larger wire (that is thicker wire) ---> less resistance, more conductivity, and with voltage held constant, yes, more current.
shorter wire, same as thicker, yes, you got it.
Wires that are cooled down.... hmmm.. If you could KEEP the wire cool, then you could keep the resistance lower, but remember the wire is turning some energy into heat, and dissapating what it can. Cooling it to begin with does nothing. (unless you can cool it to superconducting temperatures)
As far as electrical energy storage, a large capacitor can work similar to a battery. The newer supercaps are getting bigger and bigger (and cheaper). Also the work they are doing on hydrogen storage cells looks promising. (it looked promising a few years ago, maybe they are in use now, I don't know)
Remember, though that with any storage device you can't add to it and remove from it at the same time. If you have a bucket of water with a hole in the bottom, you can increase the level of water by filling it, you can decrease the level by letting it empty, you can keep it in balance, but you will never ever increase and decrease the level at the same time.
When it comes to charging batteries, you can design a circuit that makes it appear to the end user that for all practical purposes the battery is charging and discharging at the same time, but as a designer, you must realize that this is not happening.
When you start your car, you use battery power. Once started there is enough power from the alternator to run the car and all the accessories and recharge the battery and keep it topped off, but the car is running off the alternator not the battery.
You can turn on your laptop and run it off the battery for a while. When you plug it into the mains, the charger has enough power to recharge the battery and power the laptop. The laptop is running off the charging circuit, not the battery.
As an end user of a car or laptop you can imagine any sort of magical flow of electricity you want. If you as a designer start thinking of energy flowing in and out at the same time and try to make seperate pathways and limit direction of flow and all that.... I think your heading down a road that doesn't go anywhere.
You have a friend that works for a battery company. Tell him that someone online (lots of people online) told you that "technically a battery is either charging or discharging or staying steady and never charging and discharging at the same time," and see what he says. Also give him a link to this site and invite him to join and discuss.
--tim