Procedure to optimize materials for cathodes and cathode material having enhanced electrochemical properties

Method for improving the electrochemical properties of a lithiated metal polymer (LMP) technology battery, comprising one anode, one cathode, and a polymer electrolyte containing a lithium salt, where the cathode comprises a C-AxM(XO4)y material, said the method comprising:

• (i) A determination of the level of calcium present as an impurity:
• (a) in a lithiated or partially lithiated oxyanion-based material comprising particles of a compound having the formula AxM(XO4)y,
• (b) in a lithiated or partially lithiated oxyanion-based material comprising particles of a compound having the formula AxM(XO4)y, where the particles comprise carbon deposited by pyrolysis on at least part of its surface, or
• (c) the precursors of (a) or (b);
• (ii) a selection from among (a), (b), or (c) of the material or precursors containing a level of calcium present as an impurity lower than approximately 1000 ppm, preferably lower than approximately 500 ppm, preferably lower than approximately 300 ppm, and even more preferably lower than approximately 100 ppm, to be used for manufacture of the cathode, and
• wherein:
• A stands for Li, alone or partially replaced by at most 10% atomic percentage of Na or K;
• M stands for Fe(II) or Mn(II), or mixtures thereof, alone or partially replaced by at most 30% atomic percentage of the atoms of one or more other metals chosen from Ni and Co, and/or by at most 10% atomic percentage of one or more aliovalent or isovalent metals other than Ni or Co, and/or by at most 5% atomic percentage of Fe(III);
• and
• XO4 stands for PO4 alone or partially replaced by at most 10% atomic percentage of at least one group chosen from among SO4, SiO4, and MoO4;
• and
• 0<x≦2 and 0<y≦2, the coefficients x and y being chosen independently to ensure electroneutrality of the oxide complex,