is there any other alternate batteries that can be used?

I have been wondering for awhile if you can use any other alternate battery (not lead acid) that are still legal in competitions. I know that Lithium ion batteries are not legal, but I was mostly wondering about nickel-lithium batteries. I have been looking everywhere but cant seem to find a definite answer.

Read the Battery Rules:

Specifically R20

I think it will answer your question.