The invention relates to a lithium positive electrode active material for a high voltage secondary battery: the lithium positive electrode active material comprising at least 94 wt % spinel, where the spinel has a net chemical composition of Li.sub.xNi.sub.yMn.sub.2-yO.sub.4, wherein:

0.95≤x≤1.05;

0.43≤y≤0.47.

The lithium positive electrode active material is made up of particles characterized by one or more of the following parameter ranges: the particles have average aspect ratio below 1.6, the particles have a roughness below 1.35, particles have a circularity above 0.55. Then invention also relates to a process for the preparation of the lithium positive electrode active material as well as a secondary battery comprising the lithium positive electrode active material.

Disclosed are a method for preparing lithium nickel cobalt manganese oxide by reverse positioning of a power battery and use thereof. The method first mixes and grinds a positive electrode tab and a slagging agent, then dries, cools, adds an aluminum powder, mixes well, conducts a self-propagating reaction to the mixed material, cools, takes a lower layer of rough nickel cobalt manganese alloy, grinds the rough nickel cobalt manganese alloy, adds an alkali liquor, then immerses, filters, takes the filter residue for washing and then dries, to obtain a nickel cobalt manganese alloy powder, adds a lithium salt solution to the porous nickel cobalt manganese alloy powder, mixes and drips an alkali liquor, ages, filters, takes a filter residue for washing and then dries, to obtain a mixed powder of precursor, sinters the mixed powder of precursor and cools, to obtain a lithium nickel cobalt manganese oxide.

Disclosed are a method for preparing lithium nickle cobalt manganese oxide by reverse positioning of a power battery and use thereof. The method first mixes and grinds a positive electrode tab and a slagging agent, then dries, cools, adds an aluminum powder, mixes well, conducts a self-propagating reaction to the mixed material, cools, takes a lower layer of rough nickel cobalt manganese alloy, grinds the rough nickel cobalt manganese alloy, adds an alkali liquor, then immerses, filters, takes the filter residue for washing and then dries, to obtain a nickel cobalt manganese alloy powder, adds a lithium salt solution to the porous nickel cobalt manganese alloy powder, mixes and drips an alkali liquor, ages, filters, takes a filter residue for washing and then dries, to obtain a mixed powder of precursor, sinters the mixed powder of precursor and cools, to obtain a lithium nickle cobalt manganese oxide.

A lithium metal oxide powder for a cathode material in a rechargeable battery, consisting of a core and a surface layer, the surface layer being delimited by an outer and an inner interface, the inner interface being in contact with the core, the core having a layered crystal structure comprising the elements Li, M and oxygen, wherein M has the formula M=(Ni.sub.z (Ni.sub.1/2 Mn.sub.1/2).sub.y Co.sub.x).sub.1-k A.sub.k, with 0.15≤x≤0.30, 0.20≤z≤0.55, x+y+z=1 and 0<k≤0.1, wherein the Li content is stoichiometrically controlled with a molar ratio 0.95≤Li:M≤1.10; wherein A is at least one dopant and comprises Al; wherein the core has an Al content of 0.3-3 mol % and a F content of less than 0.05 mol %; and wherein the surface layer has an Al content that increases continuously from the Al content of the core at the inner interface to at least 10 mol % at the outer interface, and a F content that increases continuously from less than 0.05 mol % at the inner interface to at least 3 mol % at the outer interface, the Al and F contents in the surface layer being determined by XPS. The surface layer may also have a Mn content that decreases continuously from the Mn content of the core at the inner interface, to less than 50% of the Mn content of the core at the outer interface.

Provided is a 5 V class spinel type lithium nickel manganese-containing composite oxide having an operating potential of 4.5 V or more with respect to a metal Li reference potential, wherein the composite oxide is able to improve cycle characteristics while suppressing the amount of gas generated under high temperature environments and, moreover, to improve output characteristics while suppressing a shoulder on discharge at around 4.1 V in a charge and discharge curve. The spinel type lithium nickel manganese-containing composite oxide is represented by a general formula [Li(Li.sub.aNi.sub.yMn.sub.xTi.sub.bMg.sub.zM.sub.α)O.sub.4-δ] (where 0<a, 0<b, 0.30≤y<0.60, 0<z, 0≤α, x=2−a−b−y−z−α<1.7, 3≤b/a≤8, 0.11<b+z+α, 0<z/b<1, 0≤δ≤0.2, and M represents one or two or more elements selected from the group consisting of Fe, Co, Ba, Cr, W, Mo, Y, Zr, Nb, P, and Ce).

An electrolyte solution applicable to high-voltage electrochemical devices and capable of improving the cycle characteristics of electrochemical devices even at high voltage. The electrolyte solution contains a fluorinated acyclic carbonate and a metal salt having a specific structure. The fluorinated acyclic carbonate is represented by CF.sub.3—OCOO—R.sup.11 (wherein R.sup.11 is a C1 or C2 non-fluorinated alkyl group or a C1 or C2 fluorinated alkyl group) or CFH.sub.2—OCOO—R.sup.12 (wherein R.sup.12 is a C1 or C2 non-fluorinated alkyl group or a C1 or C2 fluorinated alkyl group).

Disclosed herein are a method of transition metal doping while simultaneously forming an ultra-thin film coating of the transition metal oxide using atomic layer deposition (ALD) on lithium ion battery (LIB) electrode particles; a product formed by the disclosed method; and the synergetic effect of the transition metal doping simultaneously with forming the ALD ultra-thin film transition metal oxide coating.

Provided is a material that can be used as a potassium secondary battery positive electrode active material (particularly a potassium ion secondary battery positive electrode active material), other than Prussian blue, by using a potassium compound and a potassium ion secondary battery positive electrode active material comprising the potassium compound, the potassium compound being represented by general formula (1):
K.sub.nA.sub.kBO.sub.m,
wherein A is a positive divalent element in groups 7 to 11 of the periodic table; B is positive tetravalent silicon, germanium, titanium or manganese, excluding a case in which A is manganese and B is titanium, and a case in which A is cobalt and B is silicon; n is 1.5 to 2.5; and m is 3.5 to 4.5.

The present invention relates to a positive electrode comprising a Mn composite oxide having a tetragonal structure represented by formula (1): Li.sub.a(M.sub.xMn.sub.2-x-yY.sub.y)(O.sub.4-wZ.sub.w)(wherein 1<a2.6, 0x1.2, 0y, x+y<2, 0w1; M is at least one selected from the group consisting of Co, Ni, Fe, Cr and Cu; Y is at least one selected from the group consisting of Li, B, Na, Mg, Al, Ti, Si, K and Ca; Z is at least one of F or Cl; and a composite oxide having a layered structure represented by formula (2): Li(Li.sub.xM.sub.1-x-yY.sub.y)O.sub.2 (wherein 0x<0.3, 0y<0.3; M is at least one selected from the group consisting of Co, Fe, Ni and Mn; Y is at least one selected from the group consisting of Mg, Al, Zr, Ti and Zn. According to the present invention, a lithium secondary battery having a high capacity and being excellent in cycle life can be provided.

The present invention relates to a method for producing lithium-nickel-manganese-based transition metal oxide particles, the transition metal oxide particles which are obtained with the method, and the use thereof as electrode material. The present invention particularly relates to lithium-nickel-manganese-based transition metal oxide particles in over-lithiated form with high tamped density, a method for production thereof and use thereof as cathode material in lithium secondary batteries.