Provided are a positive electrode active material for nonagueous secondary batteries, the material having a narrow particle-size distribution and a monodisperse property and being capable of increasing a battery capacity; an industrial production method thereof; and a nonaqueous secondary battery using the positive electrode active material and having excellent electrical characteristics. The positive electrode active material is represented by a general formula: Li.sub.1+uNi.sub.xCo.sub.yMn.sub.zM.sub.tO.sub.2+ (wherein, 0.05u0.95, x+y+z+t=1, 0x0.5, 0y0.5, 0.5z<0.8, 0t0.1, and M is an additive element and at least one element selected from Mg, Ca, Al, Ti, V, Cr, Zr, Nb, Mo, and W), has an average particle diameter of 3 to 12 um, and has [(d.sub.90d.sub.10)/average particle diameter], an index indicating a scale of particle-size distribution, of 0.60 or less.

A positive active material for a positive electrode of a battery cell which includes a first component containing a compound of general formula: Li.sub.2-zNa.sub.zM.sup.1.sub.1-yM.sup.2.sub.yO.sub.3, where M.sup.1 and M.sup.2 are different from one another and stand for transition metal ions, 0<y<1, and 0z<2, with the condition that the compound is essentially free of manganese ions. Moreover, a positive electrode of a battery cell which includes the positive material, and a battery cell which includes at least one positive electrode, are also described.

Electrode materials for electrochemical cells and batteries and methods of producing such materials are disclosed herein. The electrode materials comprise an active lithium metal oxide material prepared by: (a) contacting the lithium metal oxide material with an aqueous acidic solution containing one or more metal cations; and (b) heating the so-contacted lithium metal oxide from step (a) to dryness at a temperature below 200 C. The metal cations in the aqueous acidic solution comprise one or more metal cations selected from the group consisting of an alkaline earth metal ion, a transition metal ion, and a main group metal ion.

A method for preparing a cathode active material is provided. The method for preparing a cathode active material can comprise the steps of: preparing a first metal oxide; preparing a second metal oxide having an oxygen ratio lower than that of the first metal oxide by heat treating the first metal oxide in a nitrogen-containing gas atmosphere; and preparing a lithium metal oxide by firing the second metal oxide and a lithium salt.

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.

Substituted -MnO.sub.2 compounds are provided, where a portion of the Mn is replaced by at least one alternative element. Electrochemical cells incorporating substituted -MnO.sub.2 into the cathode, as well as methods of preparing the substituted -MnO.sub.2, are also provided.

Disclosed are a positive active material for a rechargeable lithium battery, a method of manufacturing the same, and a rechargeable lithium battery including the same. More specifically, the positive active material for a rechargeable lithium battery is a compound having an orthorhombic layered structure represented by the following Chemical Formula 1 or a compound represented by the following Chemical Formula 2, a method for producing the same, and a rechargeable lithium battery including the same.
Li.sub.1+xM.sub.yO.sub.2+z[Chemical Formula 1]
{.sub.m(Li.sub.1+xM.sub.yO.sub.2+z)}.{.sub.1-m(LiMO.sub.2)}[Chemical Formula 2] Wherein, in the above Chemical Formula 1 or Chemical Formula 2, M is one or more elements selected from the group consisting of Mn, Co, Ni, Al, Ti, Mo, V, Cr, Fe, Cu, Zr, Nb, and Ga, 0.7x1.2, 0.8y1.2, 0.2z0.2, and 0<m1.

Thermochemical storage materials having the general formula A.sub.xA.sub.1-xB.sub.yB.sub.1-yO.sub.3-, where A=La, Sr, K, Ca, Ba, Y and B=Mn, Fe, Co, Ti, Ni, Cu, Zr, Al, Y, Cr, V, Nb, Mo, are disclosed. These materials have improved thermal storage energy density and reaction kinetics compared to previous materials. Concentrating solar power thermochemical systems and methods capable of storing heat energy by using these thermochemical storage materials are also disclosed.

Provided is a method for recycling and refreshing a cathode material, a refreshed cathode material and a lithium ion battery. The method for recycling and refreshing the cathode material includes: 1) a cathode material recycled from a waste battery is mixed with a manganiferous salt solution; 2) an alkali aqueous solution is added to the mixture to react to obtain a manganese hydroxide coating cathode material; and 3) the manganese hydroxide coating cathode material is sintered with a lithium resource to obtain a refreshed cathode material. The refreshed cathode material has no obvious impurity phase and has good crystallinity, high initial charge-discharge efficiency and good cycling performance.

A ceramic member comprising a compound oxide of La, E and Mn, wherein AE is (i) Ca, or (ii) contains Ca and at least one of Sr and Ba with a total amount of Sr and Ba to a total of Ca, Sr and Ba of not more than 5 mol %, and a crystal system in a surface of the ceramic member is a monoclinic system.