Vapor chambers and heat pipes are exceptional at moving heat from a relatively small part of them to distribute it around the whole.
This is because the heat dumps into a liquid which is concentrated at the heat source, but as soon as it evaporates it fills the volume in which it’s contained. Also it’s because the evaporation process itself sucks out heat at a rate that’s orders of magnitude faster than via conduction, convection, or radiation alone.
They do not cool though. They rely on the fact that the heat source is relatively small and that something else can pull heat out of them fast enough to re-condense the liquid (and since they distribute the heat that cooling can attach anywhere or everywhere — this is like an embarrassingly parallel problem in software).
In a battery pack there is a lot of surface area that gets relatively and evenly hot, and little room to extract it between the cells. This would likely result in even heating around the heat pipe, which would tend to evaporate all of the liquid inside and do nothing but raise its overall temperature after an initial delay.
What it potentially could be used for is to draw heat out of the battery pack and up to some place where better airflow were possible, or for some active cooling system to extract the heat, but there are problems with scaling up like that (in typical heat pipes they manufacture wicking inner layers to draw the water back even against gravity).
At the points they could be used it’s likely significantly cheaper and easier to control some air or liquid cooling loop through the batteries.
Phones are ideal because a tiny little chip is producing almost all of the heat. It’s not even a lot, it’s just in a small area. Temperature goes up when heat can’t escape, so in this case, spreading the heat around even a few square inches can be a major factor in keeping down the temperature of the CPU/GPU.
Contrast this to EV batteries which are huge and produce evenly distributed heat already; there just isn’t the same value when things are big enough to add cooling systems, when cooling systems are necessary anyway, and when the heat pipe or vapor chamber just adds another piece too the system.