content: The problem with hydrogen is (and has always been) two-fold. Primarily, generation. Secondarily, storage. The cheapest source of high-yield hydrogen is through thermal cracking of fossil fuels. I don't need to explain why this is unsustainable. The second pathway for hydrogen generation is electrolysis, which is less efficient in terms of energy conversion than storing electricity in a battery. Storage has also been a big issue for hydrogen adoption. Hydrogen is a gas at room temperature, so its STP (standard temperature and pressure) energy density is very, very low. Thankfully, it can be pressurized to improve its mass per unit volume, thereby increasing its energy density, but this also has problems of its own. Hydrogen is the smallest atom by a significant margin. It leaks very readily through otherwise solid materials, and a pressurized hydrogen vessel poses a non-negligible combustion hazard when ruptured in open air. You can fairly state that battery technology has a lot of room for improvement, but hydrogen fuel cell technology isn't even at the starting line. Furthermore, where battery technology could still improve through application of novel material sciences, hydrogen sequestration and storage are butted quite squarely against thermodynamic and physical limitations that are difficult, if not impossible to work around.