NOVELTY - Carbon-metal oxide material (I) comprising particles of a metal compound (II), where the particles contain a carbon deposit deposited on at least a portion of the surface by pyrolysis and (I) has a calcium impurity content of less than 1000 ppm, preferably less than 100 ppm, is claimed.    USE - (I) is useful: for the synthesis of carbon-lithium metal phosphate of formula (C-LiMPO4), preferably carbon-lithium iron phosphate (C-LiFePO4); and in electrode and battery, which is lithium metal polymer technology (all claimed).    ADVANTAGE - The material: has improved electrochemical properties when used as a cathode in battery of lithium metal polymer technology, high storage capacity, and low levels of calcium impurities; and provides high power.    DETAILED DESCRIPTION - Carbon-metal oxide material of formula (C-AxM(XO4)y) comprising particles of a metal compound of formula (AxM(XO4)y), where the particles contain a carbon deposit deposited on at least a portion of the surface by pyrolysis and (I) has a calcium impurity content of less than 1000 ppm, preferably less than 100 ppm, is claimed.    A = Li, alone or partially replaced by at most 10 atomic% of Na or K;    M = Fe(II) and/or Mn(II), alone or partially replaced by at most 30 atomic% of one or more metals comprising Mn, Ni or Co and/or at most 5% of Fe(III);    XO4 = PO4, alone or partially replaced by at most 10 molar% of at least one group comprising SO4, SiO4 and MoO4; and    x, y = greater than 0 and less than or equal to 2, where the coefficients x and y are selected to ensure electroneutrality of the complex oxide.    INDEPENDENT CLAIMS are included for:    (1) electrode comprising a film of a composite material deposited on a conductive substrate forming the current collector, where the composite material includes (I), a binder and a electronic conductive compound;    (2) a battery comprising an anode, a cathode and a polymer electrolyte containing a lithium salt, where the cathode includes (I);    (3) process for improving the electrochemical properties of a battery of lithium metal polymer technology, comprising the anode, cathode and the polymer electrolyte containing a lithium salt, comprising: determination of the calcium impurity of (a) oxyanion material of lithium metal or partially lithium comprising the particles, (b) oxyanion material of lithiated or partially lithiated metal comprising the particles or particles comprising the carbon deposit deposited on at least a portion of the surface by pyrolysis or precursors of (a) and (b); and selecting the material of (a), (b) or (c) or its precursor for the manufacture of the cathode; and    (4) metal phosphate (MPO4) material of formula (preferably iron phosphate (FePO4)), optionally hydrated, for the synthesis of carbon-lithium metal phosphate of formula (C-LiMPO4), preferably C-LiFePO4 by a thermal process, where M is a metal of at least 70 atomic% of Fe(II).