[mowowie]

Under high pressure it turns to a liquid... I think.

[wildcard_redneck]

I believe to keep hydrogen liquid you have to keep it at a very low temperature or the pressure will get too much for the container. It isn't a natural liquid at room temperature like gasoline.

Liquid hydrogen (LH2) offers the highest storage density compared to other forms of storage, without requiring a chemical reaction. However, it requires the hydrogen be cooled to 20 K using an energy-intensive refrigeration process. LH2 storage is associated with the unavoidable evaporation of a fraction of the LH2, known as “boil-off”, which results in process inefficiency and energy losses. To ensure proper deployment and increased competitiveness of LH2 storage, evaporation should be minimized as much as possible or, alternatively, recovered in liquid or gaseous form.

Source https://www.sciencedirect.com/science/article/abs/pii/S1364032123002174