I wanted to be sure using zinc solder to connect tabs wouldn't be an electrical point of high resistance that could cause tab heating.
I just worked the numbers on the electrical resistance of zinc being used to connect the tabs.
It turns out, zinc is a pretty damn good conductor. Copper is 16.8nOhm/m, Zinc is 59nOhm/m, and our normal solder base, lead, is 208nOhm/m, and tin is 109nOhm/m. Zinc solder is an electrically superior solder to our 60/40 lead/tin electronics solder.
If you lay a 4.5mm path of zinc all the way across the tab, you've got a connection that equals half the resistance of the tab material itself, meaning it would be generating less heat at the connection than the tab itself, and I've all ready found these tabs to be incredibly capable when it comes to handling extremely high currents without getting warm.
I would recommend setting up to solder the tabs just like it would be done with an RC LiPo pack, except scaled up a bit.
A couple of 1/4" copper bars on a little spring clamp, and solder paste. The little copper bar clamp is very handy, because it not only holds the tabs together, but it makes a thermal sink/barrier from the soldering heat on the tabs ever reaching the temperature sensitive parts on the inside of the cell. Trim the tabs as desired, apply a little smear of the the solder paste on the outside area of one tab, put the clamp on the area of the tab as close to where it enters the foil package as possible, but not where it blocks the area you need to apply heat to solder the tab. Then hit the outside part of that tab with as intense of heat as you can manage. Most people use flame, but I don't like the tendency to oxidize the surface, so I use a hot gun. lol, I remember I could throughly melt the solder paste in LiPo cell pack construction in roughly a 2-second heating period by covering the back (air inlet) side of my heat gun until the coils went from red, to bright orange (just takes about 5 seconds, so be careful you don't melt your heating element!), then releasing my hand at the same time I would direct the little chisel tip of the heat gun onto the tabs. 2 seconds later, you could see the solder completely wet and flow, I pull the heat gun away, and keep my fingers on the area the tab enters the foil pouch. If done correctly, you could hardly even feel the tab on the back side of the heatsink get above room temperature.
This was all for working with LiPo cells that have 1/4" wide aluminum tabs though of course, but I can't think of why the same process couldn't simply be scaled up for connecting these monster cell tabs.
This stuff is pricey for it's tiny quanity, but it's just flux with 85% zinc micro-balls, and 15% aluminum micro-balls. It melts at a low temp and is super easy to work with for doing LiPo tabs. There are of course many larger quantity aluminum solder pastes available, but just for experimenting, this stuff is pretty common to find in hardware stores and things. I would think it, or something like it would be available in China. http://www.amazon.com/Aluminum-Solder-S ... B0017T0U3U