The galaxy brain take on Tesla is that it is just marketing wrapped around the progress that was already happening in batteries. They really actually are cheaper and have much increased energy density relative to 10 and 20 years ago.
Does lithium-ion itself count? The first practical chemistry was developed in 1979, the first commercial battery was shipped in 1991 and they went pretty mainstream between 2000 and 2005.
That's a long time if you are talking about announcements made today but there's been lots of announcements in between and there is considerably more investment now than 30 years ago.
If we're looking at breakthroughs since 30 years ago, lithium ion definitely counts. But it's pretty much the only example, and there are very severe flaws with lithium ion leaving the space ripe for improvement. Everything since has pretty much been optimization.
