Structure and Electrochemistry of LiNi[sub xCosub 1−2xMnsub x]Osub 2 (0≤x≤1/2)

In a recent paper, Lu et al. showed that and are attractive electrode materials for Li-ion cells. Most interesting, they appear to be much less reactive with electrolyte at high temperatures than Since these two materials are part of the solid-solution series with which also contains when it is possible to study the reasons for the safety advantage by a careful study of electrochemical, structural, and thermal properties as a function of This paper reports the structural and electrochemical properties of for The materials all show good specific capacity (between 110 and 130 mAh/g between 3.0 and 4.2 V vs. Li at 40 mA/g) and very little capacity loss over 50 cycles. Careful consideration of differential capacity measurements proves that and do, indeed, substitute for at least for as was hypothesized by Lu et al. The thermal stability of the charged cathode materials improves rapidly compared to then saturates as in increases. Materials with show approximately equal thermal stability. The reason for the variation of the thermal stability with is the subject of a companion paper. © 2002 The Electrochemical Society. All rights reserved.