NOVELTY - An electrode material comprises surface-coated particles obtained by coating surface of lithium phosphate particles with carbonaceous film. The surface-coated particles have lithium elution amount of 200-700 ppm and phosphorus dissolution amount of 500-2000 ppm when immersed in sulfuric acid solution having pH of 4 for 24 hours. The surface-coated particles contain lithium phosphate compound (I). The lithium phosphate particles contain lithium phosphate compound (II).    USE - Electrode material is used for manufacture of electrode plate for lithium-ion battery (all claimed) for electric vehicle and portable electronic device.    ADVANTAGE - The lithium-ion battery containing the electrode material has improved durability. The electrode material suppresses the elution of metal impurities.    DETAILED DESCRIPTION - An electrode material comprises surface-coated particles obtained by coating surface of lithium phosphate particles with carbonaceous film. The surface-coated particles have lithium elution amount of 200-700 ppm and phosphorus dissolution amount of 500-2000 ppm when immersed in sulfuric acid solution having pH of 4 for 24 hours. The surface-coated particles contain lithium phosphate compound of formula: LixAyD'zPO4 (I). The lithium phosphate particles contain lithium phosphate compound of formula: LixAyD'zPO4 (II).    A=Co, Mn, Ni, Fe, Cu or Cr;    D'=Mg, Ca, Sr, Ba, Ti, Zn, B, Al, Ga, In, Si, Ge, Sc, Y or rare-earth element;    x=more than 0 to 2;    y=more than 0 to 1;and    z=0-1.5.    INDEPENDENT CLAIMS are included for the following:    (1) electrode plate, which is obtained by forming positive electrode material layer containing the electrode material on electrical power collector;    (2) lithium-ion battery, which contains the electrode plate;    (3) manufacture of electrode material, which involves heating aggregate obtained by aggregating two or more surface-coated particles at 40-500 degrees C for 0.1-1000 hours under non-oxidizing atmosphere; and    (4) manufacture of electrode plate.    DESCRIPTION OF DRAWING(S) - The drawing shows a sectional view of the lithium-ion battery containing the electrode material.    Negative electrode (1)    Positive electrode (2)    Separator (3)    Seal portion (4)