Structural and electrochemical characteristics of Li/sub 1+x/Mn/sub 2+x/O/sub 4/ and LiMn/sub 2/O/sub 4-/spl delta// for secondary lithium batteries

摘要

A series of excess lithium doped and oxygen deficient lithium manganese oxide spinels were prepared in order to investigate the dependence of electrochemical performance on the sample structure and chemical composition. Test cells were constructed containing cathodes of synthesised compounds. Li/Li/sub 1+x/Mn/sub 2+x/O/sub 4/ cells demonstrated improved capacity retention on cycling. However, the rechargeability of Li/LiMn/sub 2/O/sub 4-/spl delta// cell was degraded. Structural damage of the spinel LiMn/sub 2/O/sub 4/ electrode probably is the main reason responsible for capacity fade. The relation between the capacity retention and the Jahn-Teller effect is discussed in detail.