Oh everywhere really. It's something I've been interested in for quiet a while. A battery related article was something I'd click on every time it came up on slashdot.
Limiting factor [1] can be really good at breaking things down and covering current battery tech (they are fairly bullish on tesla). But I also get bits and pieces from google news feeds, renewable focused social media, and diving into anti-renewable social media :D. I don't mind reading into a critical piece to challenge my preconceived notions.
It does help, though, to simply know who the big players are and watch what they are actually manufacturing (and then read up on that tech). I mostly ignore the "this battery is 8 billion times cheaper than lithium ion!" news stories because they are sensationalist. An article about CATL building a solid state battery line and now I want to know what it is, how it works, and what the cons are.
CATL is probably the most interesting manufacturer to watch if you want to know where the cutting edge is. (Similar to TSMC being cutting edge when it comes to chip manufacturing).
[1] https://www.youtube.com/@thelimitingfactor
