There were 3 versions of the Canon QL17. Yours is the earliest version. The canon museum page lists it as a 1.3v MP mercury cell, but ive also seen a similar battery listed as a PX-640, which is about double the size of the usual PX625's, but still 1.3v. So a Wein zinc-air cell will work, but you will need a adapter or something to fill in the gap. A wad of aluminum foil will work, or a spring. A 1.5 volt silver oxide or alkaline will work as well, but you will need to adjust the ISO by about half a stop.
Either way, do not stack two 1.3 or 1.5v batteries together, you will not get the correct voltage.