Actually lithium batteries are rechargeable. I can do them with my Super Brain 969 as long as I follow the 87 or so it seems warnings about doing so in the owners manuals.
It goes like, the charger can charge these batteries but you must be very carefull, set this do that this feature and that don't work with lithium and so on.
I don't know what the advantage to them is but I've heard they are the thing for racing.
I do have 8 2100 mah energizers it does no problem as well as the AAA packs for my mini x.
I use lithium all the time. You might be able to get them from wal-mar (You may have to take it out of a camcorder pack).
This site may be able to help: http://www.slavin4u.com/lithium.html
When it's down to racing, I have not lost as of yet!(don't plan on it either!)