SYNTHESIS AND PERFORMANCES OF NEW NEGATIV E ELECTRODE MATERIALS FOR ROCKING-CHAIR LITHIUM BATTERIES

New negative electrode materials for ''rocking-chair'' Li batteries we re prepared by a two-step process: solid state synthesis of crystalliz ed LiMVO4 (M = Co, Ni, Cd, Zn) precursors at 500-degrees-C in air, fol lowed by an electrochemical lithiation leading irreversibly to amorpho us materials with composition close to Li8MVO4. The average voltage of reversible Li insertion/deinsertion in these materials is about 1 V v s Li with a maximum specific capacity ranging from 700 to 1,000 Ah/kg according to M. The fast cycling behaviour of the best material, Li8Ni VO4, was studied over several hundreds of cycles. The capacity is abou t 600 Ah/kg after 100 cycles, i.e. more than 50% higher than capacitie s obtained with the best graphite materials. Comparison of volumic cap acities is even more favourable owing to the much larger densities of these materials compared to that of carbonaceous ones.