NEW AND OPTIMIZED LITHIUM MANGANESE OXIDE CATHODES FOR RECHARGEABLE LITHIUM BATTERIES

The 3 V spinel, LiM2O4.1, has been prepared by a low temperature solut ion route which includes the addition of a small amount of carbon to t he solution. As a result a significant enhancement of the capacity ret ention is obtained on cycling, reaching 50% after 300 cycles at discha rge and charge rates of C/2 and C/4, respectively. X-ray diffraction o f the composite cathode on cycling shows that the improved capacity re tention is related to a more complete conversion of the entire electro de 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 w ell as some preliminary results concerning the electrochemical perform ance are presented. A capacity of 270 mAh g(-1) is obtained on the fir st charge. Capacity fade on cycling is significant for these early mat erials. (C) 1997 Elsevier Science S.A.