New and optimised lithium manganese oxide cathodes for rechargeable lithium batteries

The 3 V spinel, LiM2O4.1, has been prepared by a low temperature solution route which includes the addition of a small amount of carbon to the solution. As a result a significant enhancement of the capacity retention is obtained on cycling, reaching 50% after 300 cycles at discharge and charge rates of C/2 and C/4, respectively. X-ray diffraction of the composite cathode on cycling shows that the improved capacity retention is related to a more complete conversion of the entire electrode between the cubic (charged) and tetragonal (discharged) structures. Layered and anhydrous LiMnO2, with a structure analogous to LiCoO2 is reported. The structure, refined using neutron diffraction data, as well as some preliminary results concerning the electrochemical performance are presented. A capacity of 270 mAh g(-1) is obtained on the first charge. Capacity fade on cycling is significant for these early materials. (C) 1997 Elsevier Science S.A.