PPS: I once bumped into a B.Eng honours graduate who recognized me from my time as a lab tech. When I asked him what he had done for his final year project, he said he had made a 750V PSU that ran from a single 1.5V battery. Intrigued by this, I asked how much current he could get out of it and he said 150 amps.
"Don't you mean 150 micro-amps?"
"No, it was definitely 150 amps."
Well I suppose given a large enough bank of capacitors, you could step the voltage upto 500v with a boost converter, and charge it at a slow rate until you've drained the cell into it, and then discharge the capacitor bank into the load circuit, it'll only supply 500v @ 150A for a mere fraction of a second, but should be possible