Effect of crystallinity on the electrochemical behaviour of spinel Li1.03Mn2O4 cathode materials

The spinel Li1.03Mn2O4 powders with a different crystallinity were synthesized by a sol-gel method from an aqueous solution of metal acetates containing glycolic acid as a chelating agent. The relation between physicochemical and electrochemical properties of the Li1.03Mn2O4 powders was studied. It was seen that as the calcination temperature increased, the lattice constant linearly increased whereas the average oxidation state of manganese linearly decreased, which resulted in an increase in crystallinity of the Li1.03Mn2O4 host. The capacity in the 4 V region Linearly increased with increasing the lattice constant of the cubic unit cell and decreasing the average oxidation state of manganese. The glycolic acid-assisted Li1.03Mn2O4 powders calcined at 800 degrees C have delivered a discharge capacity of 134 mAh/g and shown an excellent cyclability. (C) 1998 Elsevier Science B.V. All rights reserved.