A few companies do this with Prius batteries and sell them as refurbished batteries. The cells aren't too hard to disassemble and a dead cell is pretty easy to isolate. A refurbished battery is much cheaper than a brand new one from Toyota, but the batteries don't last very long before another cell eventually dies since they probably have 150k+ miles on them and Toyota, in my opinion, provided inadequate cooling for them and should have told consumers the battery's cooling system required regular maintenance.