Lithium intercalation in two-dimensional penta-NiN<sub>2</sub>: insights from NiN<sub>2</sub>/NiN<sub>2</sub> homostructure and G/NiN<sub>2</sub> heterostructure
First-principles calculations are employed to investigate the intercalation of lithium atoms in the interlayer gap of nitrogen-rich 2D bilayer NiN2 for anode applications.