A positive electrode active material for an all-solid-state lithium ion secondary battery, containing: a lithium-metal composite oxide particle having a niobium solid solution layer and a center other than the niobium solid solution layer; and a coating layer coating at least a part of a surface of the lithium-metal composite oxide particle and formed of a compound containing lithium and niobium, an average thickness of the coating layer is 2 nm or more and 1 μm or less, and an average thickness of the niobium solid solution layer is 0.5 nm or more and 20 nm or less.

There is provided a method for collecting and reusing an active material from positive electrode scrap. The method for reusing a positive electrode active material of the present disclosure includes (a) thermally treating positive electrode scrap comprising an active material layer on a current collector in air for thermal decomposition of a binder and a conductive material in the active material layer, to separate the current collector from the active material layer, and collecting an active material in the active material layer, (b-1) washing the active material collected from the step (a) with a lithium compound solution which is basic in an aqueous solution, (b-2) mixing the active material washed from the step (b-1) with a lithium precursor aqueous solution and spray drying, and (c) annealing the active material spray dried from the step (b-2) to obtain a reusable active material.

An irreversible additive contained in a cathode material for a secondary battery according to one embodiment of the present disclosure, the irreversible additive being an oxide represented by the following chemical formula 1, wherein the oxide has a trigonal crystal structure,

Li.sub.2+aNi.sub.1−bTi.sub.bO.sub.2+c   (1) in the above formula, −0.2≤a≤0.2, 0<b≤0.2, and 0≤c≤0.2.

The present disclosure provides a cathode material and a method for preparing the cathode material, a cathode, a lithium ion battery and a vehicle. The cathode material comprises a matrix particle, wherein the matrix particle is a monocrystal particle comprising nickel lithium manganate and nickel cobalt lithium manganate. A position in the matrix particle close to a surface layer is provided with a buffer layer. A content of at least one of elements Ni, Co and Mn in the buffer layer is lower than contents thereof in other positions of the matrix particle. The cathode material has at least one of advantages of relatively high specific capacity, cycling stability, better safety performance and the like, and the buffer layer can alleviate erosion by an electrolyte and inhibit separation of active oxygen.

Exemplary embodiments of positive electrode active materials in the form of single particles, and a method of preparing each of them, are provided. The single particles of the exemplary embodiments include single particles of a nickel-based lithium composite metal oxide, having a plurality of crystal grains, each having a size of 180 nm to 300 nm, as analyzed by a Cu Kα X-ray (X-rα). The single particles include a metal doped in the crystal lattice thereof. One embodiment includes a surface coating. The total content of the metal doped in the crystal lattice thereof and the metal of the metal oxide coated on the surface thereof is controlled in the range of 2500 ppm to 6000 ppm.

Disclosed is a lithium complex oxide and method of manufacturing the same, more particularly, a lithium complex oxide effective in improving the characteristics of capacity, resistance, and lifetime with reduced residual lithium and with different interplanar distances of crystalline structure between a primary particle locating in a internal part of secondary particle and a primary particle locating on the surface part of the secondary particle, and a method of preparing the same.

Process for making an electrode active material wherein said process comprises the following steps: (a) Providing a hydroxide TM(OH).sub.2 or at least one oxide TMO or oxyhydroxide of TM or combination of at least two of the foregoing wherein TM contains at least 99 mol-% Ni and, optionally, in total up to 1 mol-% of at least one metal selected from Ti, Zr, V, Co, Zn, Ba, or Mg, (b) mixing said hydroxide TM(OH).sub.2 or oxide TMO or oxyhydroxide of TM or combination with a source of lithium and an aqueous solution of a compound of Me wherein Me is selected from Al or Ga or a combination of the foregoing and wherein the molar amount of TM corresponds to the sum of Li and Me, (c) removing the water by evaporation, (d) treating the solid residue obtained from step (c) thermally at a temperature in the range of from 500 to 800° C. in the presence of oxygen.

A positive electrode material includes a first powder. The first powder includes first secondary particles. The first secondary particles includes at least two first primary particles. An average particle diameter D1 of the first primary particles is 500 nm to 3 μm. An average particle diameter D2 of the first secondary particles is 2 μm to 8 μm. A ratio K1 of D2 to D1 satisfies: 2≤K1≤10. The first powder includes an element Co and optionally further includes a metal element M. The metal element M includes at least one of Mn, Al, W, Ti, Zr, Mg, La, Y, Sr, or Ce. A molar ratio R1 between Co and M is greater than or equal to 5. The positive electrode material achieves relatively high rate performance and safety on the basis of achieving a relatively high energy density.

The present disclosure provides an irreversible additive contained in a cathode material for a secondary battery, wherein the irreversible additive is an oxide represented by the following chemical Formula 1, and wherein the oxide has a trigonal structure, a cathode material including the irreversible additive, and a secondary battery including the cathode material:

Li.sub.2+aNi.sub.1-bMo.sub.bO.sub.2+c  (1) in Formula 1, −0.2≤a≤0.2, 0<b≤0.2, 0≤c≤0.2.

The production method is a method for producing a positive electrode active material for a lithium ion secondary battery which contains at least nickel and lithium, the method including: a firing process in which a mixture of a nickel compound powder and a lithium compound powder is fired; and a water washing process in which a lithium-nickel composite oxide powder obtained in the firing process is washed with water, wherein the firing process is performed under conditions such that a value obtained by dividing a ratio of an amount-of-substance of lithium to a total amount-of-substance of transition metals other than lithium in the lithium-nickel composite oxide powder after the washing with water by a ratio of an amount-of-substance of lithium to a total amount-of-substance of transition metals other than lithium in the lithium-nickel composite oxide powder before the washing with water exceeds 0.95.