Living Battery: Given the amount of biotechnology around the place, it should not surprise you that there are, yes, more than a few living batteries.
It’s just that they’re all lifeforms specifically created to serve as living batteries – large cultures of Spheroporus electri inside microbial fuel cells, artificial organs rich in electrophores, that sort of thing. Insert food, get pumped electrons. This is vastly more practical, you see, than trying to use existing living creatures, which are generally not designed to optimize the production of electrical power.