چكيده به لاتين
One of the big human challenges is the need for electrical energy storage devices with high energy density and cyclicity. Lithium batteries are one of the most important energy storage tools, and among them, lithium-air batteries have unique features that make them very prominent and distinctive. The very high energy density of this type of battery (11400 Wh / kg), which is something close to the energy density of gasoline, is its biggest advantage, but there are still some shortcomings such as high potential overcharge and low cyclicity in this battery that prevent it from becoming industrialized. In this study, using free energy changes, the overpotential of the discharge process resulting from the use of graphitic carbon nitride as a cathode of lithium-oxygen battery in the first charge-discharge cycle by DFT method has been investigated, which obtained 0.38 V. Due to the strong adsorption of lithium on graphitic carbon nitride, it is predicted that lithium will not separate from the cathode structure during the discharge process. Therefore, the overpotential of the discharge process in the second charge-discharge cycle is calculated assuming that the initial lithium remains on the cathode, which is equal to 0.80 V. In order to reduce the overpotential and also to reduce the energy of lithium adsorption on graphitic carbon nitride, elements such as sulfur, oxygen and phosphorus have been doped on graphitic carbon nitride and their overpotential has been investigated. The results are 0.41 V, 0.68 V and 0.70 V, respectively. Due to the additional potentials obtained as well as the energy of lithium adsorption on the studied structures, graphitic carbon nitride doped with sulfur can be a good option for use as a cathode for lithium-air batteries.
