Design and property investigations of manganese-based cathode material Li delta Ni0.25-zMn0.75-zCo2zOy (0 = delta = 1.75) for lithium-ion batteries

摘要

On the foundation of Li-Ni-Co-Mn quaternary phase diagram, a series of manganese-based cathode materials Li delta Ni0.25-zMn0.75-zCo2zOy (0 = delta = 1.75, z = 0, 0.05, 0.15 and 0.25) have been designed and systematically studied. These materials are synthesized via a carbonate co-precipitation route and followed by a solid-state reaction. The effects of cobalt and lithium contents on phase transformations morphologies, and electrochemical behaviors of the cathode materials are overall compared and evaluated. The results reveal that, with delta increases, structures of the materials present phase evolution from spinel phase (delta = 0.5) to integrated composite of spinel and layered phase (Fd (3) over barm and R (3) over barm, 0.5 delta 1.5) and then to a pure layered phase (R (3) over barm and C2/m, delta = 1.5). In addition, size of primary particle and roughness of the secondary particles are also affected by delta value. Moreover, it is found that the initial discharge capacity and cycle stability of the cathode materials can be improved by a proper amount of cobalt substitution for both spinel and layered structure. These studies on the Li-Ni-Mn-Co quaternary phase diagram provide a new insight into the research and development of the cathode materials for advanced lithium-ion batteries. (C) 2018 Published by Elsevier Ltd.