Electrochemical studies of ternary and quadruple lithium metal nitrides synthesized by ballmilling

Quadruple Li2.6Co0.2Cu0.2N and Li2.6Ni0.2Cu0.2N compounds with a hexagonal structure like Li3N were synthesized by high-energy ballmilling under N2 atmosphere. The Li2.6Co0.2Cu0.2N sample obtained by using CoCu alloy and Li3N as precursors exhibits high electrochemical activity and reversibility. Its initial specific capacity is 609 mA h/g and 91% of the initial capacity can be retained at the 45th cycle. This result shows that the Li2.6Co0.2Cu0.2N has better cycling stability than ternary Li2.6Co0.4N and Li2.6Cu0.4N. On the other hand, the Li2.6Ni0.2Cu0.2N has poor electrochemical reversibility. Only about 66% of initially extracted lithium can be inserted for cycling.