High-voltage LiMgδNi0.5−δMn1.5O4 spinels for Li-ion batteries

Abstract New high-voltage cathode materials for lithium and Li-ion batteries, with the general formula LiMg δ Ni 0.5− δ Mn 1.5 O 4 ( δ =0.00, 0.05 and 0.10), have been synthesized and characterized. The crystal structure of these cubic spinel materials has been refined with space group P 4 3 32 with the following site occupation: Li + on 8c, Mg 2+ on 4b, Ni 2+ on 4b/12d, Mn 4+ on 12d/4b and O 2− on 24e and 8c. Refinement with space group Fd 3 m was not possible. As a function of the Mg content, it was found that: (I) the cubic lattice constant increases from 8.1685 A ( δ =0.00) and 8.1703 A ( δ =0.05) to 8.1733 A ( δ =0.10); (II) the flat potential profile at 4.7 V vs. Li/Li + ( δ =0.00) changes to a slightly sloping profile with an increased average potential of 4.75 V ( δ =0.10); (III) the cyclability and the conductivity of the materials improve. It is concluded that LiMg δ Ni 0.50− δ Mn 1.5 O 4 ( δ 4 , can result in ∼3.25 V rechargeable Li-ion battery with spinel electrodes.