Therefore, researchers around the world are working to continuously improve their performance, for example by increasing their energy density. “One way to achieve this is to increase the operating voltage,” says Mario El Kazzi from the Center for Energy and Environmental Sciences at Paul Scherrer Institute PSI. To solve this problem, El Kazzi and his team have developed a new method to stabilise the surface of the cathode by coating it with a thin, uniform protective layer. In a further step, the researchers tested the effectiveness of the protective coating by carrying out electrochemical tests at high operating voltages. The gratifying result: The protective coating remained stable even at high voltages.