Abstract: The present invention relates to an electrochemical device, comprising a negative electrode comprising a nitrogen-containing electron storage material, a positive electrode, and an electrolyte, wherein the nitrogen-containing electron storage material has a two-dimensional or a three-dimensional covalent structure, contains heptazine and/or triazine moieties, and is capable of intercalating and de-intercalating cations. The present invention is further directed to a uses the material, a photorechargeable battery, an autophotorechargeable battery, a redox-flow-battery, a method for harvesting light and storing electrical energy, a method for detecting and removing oxygen, and a method for detecting light.