LiAlyCo1-yO2 (R(3)over-bar-m) intercalation cathode for rechargeable lithium batteries

LiAlyCo1-yO2 solid solutions of alpha-NaFeO2 structure type have been synth esized from homogeneous hydroxide precursors. X-ray powder diffraction and scanning transmission electron microscopy show that single-phase solid solu tions are formed up to y approximate to 0.5 at 800 degrees C in air. Electr ochemical tests using nonaqueous liquid electrolyte cells shows that the op en-circuit voltage and working voltage increase with Al content as predicte d by ab initio calculations [Ceder et al., Nature, 392, 694 (1998)],(1) whi le capacity fade was significant during cycling at room temperature. Howeve r, both the absolute capacity and cycleability were improved at 55 degrees C. (C) 1999 The Electrochemical Society. S0013-4651(98)08-006-9. All rights reserved.