Easy to implement, perhaps. But not very effective. And liquid cooling has both safety concerns and is more expensive to implement.
There is a real reason why a passive cooled BEV should exist, at least in climates where battery life is reasonable.
I agree. For different climates different solutions. In California, all Leafs should have naked battery (not covered with plastics) and
lots of air passages. That would help considerably. In Norway, no need for cooling, just heating and even thermal insulation.
About liquid cooling. Battery cells absolutely do not care the medium that is used for cooling. Be it refrigerant tube walls,
cold air or liquid glycol. Battery only cares about the temperature, in the worst possible place (so usually in the center of the cell).
If Leaf had that eNV200 cooling unit, it would help a LOT. BUT.... it would not help for those Leafs that degraded all the time at
30-35*C weather. As cooling unit mostly only works when parked (it is unreasonable to keep it running randomly when parked.
Problem with Leaf is chemistry, that does not accept 40*C in 30-35*C climate. That was the biggest mistake.
Tesla's chemistry loves 40*C. Though hates cold. So much that Tesla is CONSIDERABLY worse than Leaf, for my climate.
Not that it degrades. No. It is just heavily restricting and heat-hungry.