How are batteries cooled in passenger aircraft? What sort of systems are used to cool batteries in the air? Liquid cooled? Air cooled? 

I am interested in lithium chemistry batteries in the form of either pouch cells or 18650 batteries inside of boxes placed in the fuselage or wing.
As far as I can tell, current aviation lithium batteries do not use active cooling.

I know the True Blue Power TB17 (Robinson R44 &amp; R66, Bell 505 Jet Ranger X) and TB44 (Cessna Caravan, DHC-6, DHC-8) do not require active cooling.

I haven't seen any easily accessible info on the Saft batteries for the A350.