Well, from a weight standpoint, an equal amount of available energy stored as hydrogen, is going to be way less than the equivalent in a battery. Storing hydrogen in a high pressure gaseous state still takes some volume, whereas storing the same amount in a slurry, along with the equipment to extract it, probably won't, and it's much easier to transport, so could be available more places. 2-3 pounds of hydrogen move an EV about 300-miles. A battery pack is going to likely be in the 700-800 pound range.
The hassle with any hydrogen is, most of it is not green (2-3% of supply), and unless you have an excess amount of energy available, it's nowhere near as efficient as storing it in batteries. It only makes sense if you have some renewable energy source, (tidal, solar, wind) that has an excess available that could be used to make hydrogen rather than turning those sources off, or throttling them down to keep the power distribution network intact. Some of those can produce lots of energy when the world sleeps. Today, they tend to just turn off the more expensive fossil fuel plants. We still need a buffer in case the green energy dips (a cloudy day, the wind dies down, for example), but batteries COULD be used for this, and Australia has built a pretty large demonstration plant for this by Tesla, and is expanding it after finding it worked for them.
If you make your H2 from natural gas, or do electrolysis from coal, oil, or natural gas powered plants, it's not all that green, and more of an impact than using that power to charge batteries, which don't lose that much and is generally available nearly everywhere in the industrialize world.
But, if and when we ever get into the situation where we can easily make more power than we need, storing it in hydrogen may make some sense. Tidal and wave energy goes on constantly, where wind and solar can be sporadic. Maybe if we figure out fusion reactors...we'll be swimming in excess power capacity, and more options will show up!
Recently read an article about using hydrogen in the steel making process rather than coke. You need something that can extract the oxygen in the iron oxide, and instead of making carbon dioxide in the process, a demonstration plant is doing it with hydrogen, making water in the process rather than CO2. Steel making produces about 8% of the CO2 annually, so is a significant factor if we ever want to get to a net zero situation. So, regardless, there will be continuing efforts to more efficiently make hydrogen...what we end up doing with it, is still up in the air, and making water is much better than CO2!
2014 i3 BEV, 2021 X5 45e
(The i3 will be sold soon, <17K-miles, interested?)