MATIERE ELECTROCHIMIQUEMENT ACTIVE POUR ELECTRODE POSITIVE DE GENERATEUR ELECTROCHIMIQUE RECHARGEABLE AU LITHIUM

La présente invention a pour objet une matière électrochimiquement active résultant de la substitution d'une partie du nickel d'un oxyde mixte de nickel et de lithium du type LiNiO2 cristallisant dans une structure rhomboédrique et répondant à la formule :Li (Ni(1-x-y-z-t) Cox MnyLiz Mt) O2-e Feoù 0 ≤ x < 0,700,05 < y ≤ 0,500 ≤ z ≤ 0,200 ≤ t ≤ 0,300,01 < e ≤ 0,500,20 ≤ (1-x-y-z-t)et dans laquelle M est au moins un élément parmi Mg, Al, B, Ti, Si, Zr, Fe, Zn, Cu. Electrochemically active material (I) comprises more than 97 wt.% of a rhombohedral crystal phase comprising a mixed oxyfluoride (II) of lithium, nickel and manganese. Electrochemically active material comprises more than 97 wt.% of a rhombohedral crystal phase comprising a mixed oxyfluoride of formula Li(Ni ( 1 - x - y - z - t )Co xMn yLi zM t)O 2 - eF e (II) x : greater than or equal to 0 and less than 0.7; y : greater than 0.05 and less than or equal to 0.5; z : greater than or equal to 0 and less than or equal to 0.2; t : greater than 0 and less than or equal to 0.3; e : greater than 0.01 and less than or equal to 0.5; (1-x-y-z-t) : less than or equal to 0.20. M : Mg, Al, Bi, Ti, Si, Zr, Fe, Zn and/or Cu. Independent claims are also included for: (1) positive electrode for a rechargeable lithium battery, comprising a conductive support covered with an active layer containing (I); (2) rechargeable lithium battery comprising a positive electrode containing (I) and a negative electrode whose active material is metallic lithium, a lithium alloy or a material into whose structure lithium can be inserted.