[potato3732842]

You can't actually assess these things without hindsight. At any given time there's a dozen promising looking things but most of them never work out.

Lithium batteries were "coming soon" for like 30yr.

[XorNot]

Which isn't the question: what promising things was the Boring company looking at? Not what they said they wanted to achieve, how were they planning on doing it?

Lithium batteries at all points were quite specific "we think <process> will reduce costs and make them viable".