Electrochemical studies of a new anode material, Li3 − xMxN (M = Co, Ni, Cu)

Li3 − xMxN (M = Co, Ni, Cu) with hexagonal symmetry, P6/mmm, was prepared by heating a mixture of Li3N and metallic powder in a nitrogen gas stream. Solid solutions of Li3 − xMxN are formed in the range of 0 ≤ x ≤ 0.5, 0 ≤ x ≤ 0.6, and 0 ≤ x ≤ 0.3 for M = Co, Ni and Cu, respectively. The cycle performance in an Li/Li3 − xMxN cell was studied in the cell voltage range between 0.01 and 1.5 V. The lithium ion is easily cycled over a wide range of 0.0 ≤ z ≤ 1.0 in Li3 − x − zCoxN and is also cycled fairly well Li3 − x − zCuxN with the cell voltage range between 0 and 1.1 V. It is characteristic that the charge and discharge curves of the second cycle differ from the first one. On the other hand, in the Li/Li3 − xNixN cell, the lithium ion is only cycled in a narrow range of 0.0 ≤ z ≤ 0.5 between 0.01 and 1.5 V, while the charge and discharge curves of the second cycle are almost similar to the first one.