MXenes are able to store large amounts of electrical energy like batteries and to charge and discharge rather quickly like a supercapacitor. They are thus a very interesting class of materials for energy storage. The material is structured like a kind of pastry, with the MXene layers separated by thin water films. A team at HZB has now investigated how protons migrate in the water films confined between the layers of the material and enable charge transport. Their results have been published in the journal Nature Communications and may accelerate the optimization of these kinds of energy storage materials.