Solid-state redox potentials for Li[Me1/2Mn3/2]O-4 (Me : 3d-transition metal) having spinel-framework structures: a series of 5 volt materials for advanced lithium-ion batteries

A series of spinel-framework structures of Li[Me1/2Mn3/2]O-4 (Me; Ti, Cr, F e, Co, Ni, Cu, and Zn) was prepared and examined by XRD and electrochemical methods. All samples except Li[Ti1/2Mn3/2]O-4 and Li[Zn1/2Mn3/2]O-4 exhibi ted approximately 5 V solid-state redox potentials (vs. Li+/Li), probably d ue mainly to compact crystal fields imposed by the spinel-framework structu re of cubic close-packed oxygen linked with tetravalent manganese ions. Of these, Li[Fe1/2Mn3/2]O-4 and Li[Ni1/2Mn3/2]O-4 are very attractive material s in both basic and applied research fields, and the solid-state redox pote ntials of transition metal ions in such crystal fields are summarized and d iscussed. (C) 1999 Elsevier Science S.A. All rights reserved.