A new copolymer-based battery developed by researchers at Ulm and Jena universities in Germany stores energy from sunlight for days and can release it when required as green hydrogen. The battery is rechargeable, and the charge and discharge process can be activated by flipping a pH switch, a press release said.
With the focus on switching away from fossil fuels, countries are adopting large-scale solar and wind power plants. However, for applications requiring higher energy density, hydrogen is a more viable alternative. It can be burnt, much like a fossil fuel, but produces only water as a byproduct, offering a carbon-free solution for energy-intensive applications.
It's currently a work in progress and it's often that articles don't go into full detail on that work but it links to this this article which goes into further detail and may answer some of your questions. Constructive comments are more appreciated than cynicism