Technically, 'battery that lasts forever' should be a perfectly good description to use, at least for a start, so maybe she should just accept that and move on.

But... nah.

"Hmm... maybe, but if that is the case - Mr. Luthor, would you like to explain when, exactly, your corporation started using magic? I don't believe we have that on record at the moment." Her voice is so exaggeratedly sweet and earnest that there is basically no way not to parse it as sarcasm.