The Spinel Phase of LiMn2 O 4 as a Cathode in Secondary Lithium Cells

Abstract

Theelectrochemical properties of LiMn2O4 and LiMyMn2–yO4 (M = Ti, Ge, Fe, Zn, or Ni) were studied for differentconditionsof sample preparation and different degrees of cation substitution (y).In the voltage range 3.5–4.5 V, cells of eitherspinel LiMn2O4or -MnO2 (made by leaching the Li from LiMn2O4) reversiblyinsert 0.4 Li per Mn at an average voltage of4.1V, leading to an energy density of 480 Wh/kg ofcathode. Cells cycled 50 times lost less than 10% oftheir initial capacity,suggesting that this material could be used insteadof LiCoO2 or LiNiO2 as the cathode in the newgeneration of "rockingchair batteries." Replacing Mn with cations of valence2 (Ni, Zn) or 3 (Fe) reduces the amount ofMn+3 and correspondinglyreduces the capacity of the cells at 4.1V, but does not affect their cycling performance. ©1991 The Electrochemical Society, Inc.