This isn’t really an “emerging” battery tech, and there have been all kinds of hyped “breakthroughs” about hydrogen batteries for a long time. The issue here, like always, is that it does not scale, the cost is absurd, the tech is improving slower than Lithium batteries, and this essentially takes the working parts of a fuel cell but makes the storage foolishly low.
There are also no end-of-life environmental challenges with a proton battery, since all components and materials can be rejuvenated, reused or recycled.”
The same is true of Lithium cells, but the problem historically has been that recycling is more expensive because the volume of cells being recycled is vanishingly small. The ability to recycle a product doesn’t determine whether or not it is recycled, which is a really unfortunate truth we have to face.