INFLUENCE OF MORPHOLOGY ON THE STABILITY OF LINIO2

LiCoO2 is currently used as a cathode material in most commercial lith ium-ion batteries. Lithium intercalation compounds such as LiNiO2 are being pursued as lower cost alternatives to LiCoO2. Although cathodes of LiNiO2 provide higher capacity at a lower cost the layered structur e becomes unstable during the cell charging process as the material is delithiated. The instability of LiNiO2 in lithium-ion cells reduces t he cycle life of the cell and leads to safety concerns. Ir, this paper we determine the influence of particle size and particle morphology o n the thermal stability of lithiated LiNiO2. Five different particle s ize (P-c) cathode materials were prepared by a proprietary Westaim pro cess and the thermal and electrochemical stability determined. Thermog ravimetric analysis indicates that the thermal stability of LiNiO2 dep ends on P-c, not on the particle size of the agglomerate (P-a). LiNiO2 with a large P-c is more thermally stable than those with a small P-c . The LiNiO2 cathode material exhibits a reversible electrochemical ca pacity of about 150 mAh/g when tested in an Li/LiNiO2 cell. The LiNiO2 cathode material with a large P-c has a slightly lower reversible cap acity than that with a small P-c. (C) 1997 Elsevier Science S.A.