NEGATIVE ELECTRODE FOR LITHIUM BATTERIES

摘要

An active material for high-voltage negative electrodes (>1V vs. Li) of secondary rechargeable lithium batteries is disclosed. Chemical composition is represented by the general formula Li2+vTi3−WFeXMyM′ZO7−α, where M and M′ are metal ions having an ionic radius between 0.5 and 0.8 A and forming an octahedral structure with oxygen, like Ti3+, Co2+, Co3+, Ni2+, Ni3+, Cu2+, Mg2+, Al3+, In3+, Sn4+, Sb3+, Sb5+, α is related to the formal oxidation numbers n and n′ of M and M′ by the relation 2α=v+4w−3x−ny−n′z and the ranges of values are −0.5≦̸V≦̸0.5, 0≦̸w≦̸0.2, x>0, y+z>0 and x+y+z≦̸0.7. The structure is related to that of ramsdellite for all the compositions. The negative active material is prepared by ceramics process wherein lithium oxide, titanium oxide, iron oxide, M and/or M′ oxide are used as starting material for synthesis. Inorganic or organic solid precursors of the oxides can also be used instead. After reactant dispersion the mixture is fired. The resulting electrochemically active material provides low working voltage and capacity with excellent cycling capabilities at both low and high current densities.