As a current non revenue company, obviously they have a long term time line, so comparing TSLA, which is well established and the current leader in batteries, to a relative startup, 4 years out, I don't think that is a fair comparison.
The question is, kind of like TSLA,( though again at different points in the timeline), is the current market cap just too far ahead of it's future earnings? Given the apparent huge future growth in the sector they may not be.
As per fuel cells, that segment is doing pretty well as well.