Both the spent fuel and the cells are totally recyclable (where recyclable means transforming them into some amount of inert nontoxic stuff and some amount of useful stuff.) I would bet that recycling spent fuel rods is more expensive than recycling spent chemical batteries.

Also, the spent batteries, while toxic, don't require 24x7 armed security. Also the spent fuel recycling process potentially increases the need to secure the resultant materials, depending on what you're doing.