I'm not a mammal, no flier-by-night,
(though I too have been known to give you a fright).
And you might just stutter when finding my name
(but I'll give you energy to try again).
My end is quite short - and it's part of a key.
(Just please use the right way to dispose of me!)
And one more stanza, just for fun:
Still stuck? Here, try this: you can buy me with money,
or sometimes with Na, if you're being funny.
What am I?