I looked at Li-Ion AA batteries but the fact that they run at 3.6 volts instead of the 1.2 volt NiMH or 1.5 volt Alkaline/lithium AA's was a negative.  Imagine someone getting hold of those with the thought that they were a direct substitute for standard AA batteries -- no thanks.  
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Better is the Enemy of Good Enough.  
Okay, what’s your point??