Li2.7Mg0.3N was synthesized by using a mixture of Li3N and Mg metal as starting materials. Atomic absorption, XRD and Coulombic titration tests are carried out for the studies on the constitution and properties of Li2.7Mg0.3N. Atomic absorption analysis reveals the constitution of the sample is Li2.74Mg0.26N. It is shown that Li2. 7Mg0.3N has a tetragonal structure with the cell parameters of sample a=0.388 nm, c=0.547 nm. The sample's specific capacity is 1695 (mA.h) /g, the maximum of Li^+ intercalation is 2.5276; the intercalation free energy of Li^+ △Gin obtained from the EMF(x) data is =-397.51 kJ/mol; the chemical diffusion coefficient of Li^+ into Li2.7Mg0.3N is determined to be about 5.90×10^-^11～7.23×10^-^10 cm^2/s at room temperature and a series of thermodynamic and kinetic parameters is gained. Thermodynamic factor dlaai/dlnci is 10.91, ion electrical conductivity σi is 1.15×10^-^6 S.cm^-^1; component diffusion coefficient Di is 5.4×10^-^11 cm^2.s^-^1; ion mobility μi is 2.58× 10^-^9 s^-^1.cm^2.V^-^1.

Key words: MAGNESIUM, X-RAY DIFFRACTION ANALYSIS, ATOMIC ABSORPTION SPECTROPHOTOMETRY