German battery recharges using sunlight, releases hydrogen on demand

Researchers at Ulm and Jena universities in Germany have developed a novel copolymer-based solar battery that efficiently stores sunlight energy and releases it as green hydrogen on demand. The system achieves a high charging efficiency of 80% and maintains a discharge efficiency of 72%, making it a promising technology for sustainable energy storage. The battery operates through reversible redox reactions and uses a pH switch to control the charge and discharge cycle: changing the pH triggers hydrogen release via a catalyst, while exposure to sunlight recharges the system. The battery’s state of charge is visually indicated by a color change from yellow (discharged) to violet (charged). This innovation addresses the need for carbon-free hydrogen production, which is crucial for replacing fossil fuels in high energy-density applications such as electric vehicles, steel manufacturing, and clean electricity generation. Unlike conventional hydrogen production methods that rely on methane reforming and emit carbon, this system produces green hydrogen directly from solar energy. The combination of macromolecular polymer chemistry and