Electrochemical and Structural Properties of xLi₂M'O₃●(1-x)LiMn_0.5Ni_0.5O₂ Electrodes for Lithium Batteries (M' = Ti, Mn, Zr; 0 ≤ x ≤ 0.3)

Jeom-Soo Kim, Christopher S. Johnson, John T. Vaughey, and Michael M. Thackeray*
Electrochemical Technology Program, Chemical Engineering Division,
Argonne National Laboratory, Argonne, Illinois 60439

Stephen A. Hackney
Department of Metallurgical and Materials Engineering,
Michigan Technological University, Houghton, Michigan 49931

Wonsub Yoon
Brookhaven National Laboratory, Upton, New York 11973

Clare P. Grey
Department of Chemistry,
State University of New York, Stony Brook, New York 11794

Electrochemical and structural properties of xLi₂M'O₃●(1-x)LiMn_0.5Ni_0.5O₂ electrodes (M' = Ti, Mn, Zr; 0 ≤ x ≤ 0.3) for lithium batteries are reported. Powder X-ray diffraction, lattice imaging by transmission electron microscopy, and nuclear magnetic resonance spectroscopy provide evidence that, for M' = Ti and Mn, the Li₂M'O₃ component is structurally integrated into the LiMn_0.5Ni_0.5O₂ component to yield “composite” structures with domains having short-range order, rather than true solid solutions in which the cations are uniformly distributed within discrete layers. Li₂TiO₃ and Li₂ZrO₃ components are electrochemically inactive, whereas electrochemical activity can be induced into the Li₂MnO₃ component above 4.3 V vs Li⁰. When cycled in lithium cells, xLi₂M'O₃●(1-x)LiMn_0.5Ni_0.5O₂ electrodes with x = 0.3 provide capacities in excess of 300 mA●h/g over the range 4.6-1.45 V.

Copyright © 2004, American Chemical Society

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