First-Principles Studies on the Structural Stability of Spinel ZnCo 2 O 4 as an Electrode Material for Lithium-ion Batteries.

Systematic first principles calculations were performed for ZnCo2 O4 to clarify its structural and electronic properties, and particularly the structural stability as an electrode material for lithium-ion batteries. For samples with low Li concentration, e.g., Lin ZnCo2 O4 with n < 1, Li atoms take the center of oxygen octahedra and may diffuse rapidly. Structure distortions and volume expansions can be observed in Lin ZnCo2 O4 with n > 1 and amorphous structures eventually prevail. The AIMD simulations for Li9 ZnCo2 O4 suggest the formation of Li2 O, Co3 O4 and LiZn local compounds or alloys. In particular, the formation of Zn-Co aggregations and the losing of ZnO pairs are identified as the possible reasons that are responsible to the Li capacity fading in ZnCo2 O4 anodes.