I hate to say anything that makes sense, while you guys are busy arguing but...
The simple, low cost way to reduce temperature induced battery degradation in the Leaf Pack is
A-I-R--C-O-O-L-I-N-G. Introducing forced air cooling is the obvious way to get rid of waste heat.
This added greatly to the simplicity and reliability of the VW. Each aluminum skinned "cell" has a large amount of surface area, painting these black improves thermal conductivity even more.
Ram air cooling can provide much if not all of the required flow at speed, and a squirrel cage blower can do it at low speed.
Liquid cooling, with a1000 O-rings ( as in the Volt Battery) is a long term nightmare .
Look at some YouTube videos of the two battery types disassembled... and you wont want to own a volt or tesla
battery .
KISS Prinicple. Nobody talks about the admirable Leaf progressive refinement program which is so similar to what made the VW bug so successful, and so much improved over its many decades of production. Maintaining optimal battery temps also has some minor range implications.. but the longevity issue, especially in hot climes and under quick charge regimes make adding aircooling the obvious elephant in the room