In regards with Krastorio2 compatibility, you could use the lithium-sulfur battery to generate some train powerpack.

using it as a difference for alkaline to non-alkaline powerpack?
a more advanced powerpack?
for the moduled powerpack?

In regards with Krastorio2 compatibility, you could use the lithium-sulfur battery to generate some train powerpack.

using it as a difference for alkaline to non-alkaline powerpack?
a more advanced powerpack?
for the moduled powerpack?

I'm not too familiar with the K2 mod since I haven't played it before, but altering recipes slightly in the presence of K2 is something I could definitely do. In my opinion, if lithium-sulphur batteries are more advanced than the batteries used to create all the current powerpacks, then it makes sense to add them perhaps to the moduled powerpacks, as they are intended to sort of be the end of the line in terms of performance.

The issue that comes with changing any recipes would be for those who have already automated production and use K2 would need to at best change a few supply lines and at worst not notice that production has stopped.

What do you think?

I don't believe it's a big issue, since the difference in recipe between battery and lithium-sulfur battery is changing iron for lithium.
And, for me, it would make sense to require a bit more for a better powerpack. I could say even to increase the level for the module, but I don't know the stats.
And, on my view (again), the train is unlocked too early for K2SE playthrough. I could have it unlocked it before nuclear locomotive (a worse train in terms of performance).

I don't believe it's a big issue, since the difference in recipe between battery and lithium-sulfur battery is changing iron for lithium.
And, for me, it would make sense to require a bit more for a better powerpack. I could say even to increase the level for the module, but I don't know the stats.
And, on my view (again), the train is unlocked too early for K2SE playthrough. I could have it unlocked it before nuclear locomotive (a worse train in terms of performance).

Ah ok. I changed the recipe for the module powerpacks from tier threes (vanilla) to tier 1 (SE) so you would be able to unlock them before getting to space. I made this change cos I am aware that modules are a lot harder to unlock in SE, and since I haven't done a playthrough of it, I was unsure where to rebalance the recipe to. Without SE the default recipe is tier three modules for each advanced powerpack.

As someone who has a SE/K2 world would it seem balanced to increase the module requirement to tier 2? (As a NTS I would probably need to add those modules as a prerequisite for those powerpack researches.)

I believe it would be fairer. And it would make more sense to only be able to upgrade the powerpack a bit later not just in the moment you just researched it.
And I would reduce the technology cost for electric wagon locomotive. It's a bit too much for a cosmetic change.

Btw, if you want to unlock before going to space, you could require rocket tech card. You don't need to go to space to produce it (just launch a rocket (you can't go to space yet here)), you unlock tier 2 module just after, and it needs some progress after chemical tech card. I believe it would be more balanced this way.