A process for making an at least partially coated electrode active material may involve, with an electrode active material of formula Li.sub.1−xTM.sub.1−xO.sub.2, wherein TM is a combination of Ni, Co and, optionally, Mn, and, optionally, at least one metal selected from Al, Ti and Zr, and x is in the range of from 0 to 0.2, treating the electrode active material with at least one compound of W or Mo that bears at least one group or ion that is replaced or displaced when such compound reacts with the surface of the electrode active material particle, treating the surface-reacted material with an agent to decompose the compound of W or Mo, repeating the sequence 1 to 100 times, wherein the average thickness of the resulting coating is in the range of from 0.1 to 50 nm.

The present invention provides a positive electrode active material for a lithium secondary battery including a core including first lithium cobalt oxide, and a surface modifying layer positioned on a surface of the core. The surface modifying layer includes a lithium compound discontinuously distributed on the surface of the core, and second lithium cobalt oxide distributed while making a contact with or adjacent to the lithium compound, with a Li/Co molar ratio of less than 1. The positive electrode active material according to the present invention forms a lithium deficient structure in the positive electrode active material of lithium cobalt oxide and changes two-dimensional lithium transport path into three-dimensional path. The transport rate of lithium ions may increase when applied to a battery, thereby illustrating improved capacity and rate characteristic without decreasing initial capacity.

Provided is a secondary battery including a hydroxide-ion-conductive ceramic separator. The secondary battery includes a positive electrode; a negative electrode; an alkaline electrolytic solution; a ceramic separator that is composed of a hydroxide-ion-conductive inorganic solid electrolyte and separates the positive electrode from the negative electrode; a porous substrate disposed on at least one surface of the ceramic separator; and a container accommodating at least the negative electrode and the alkaline electrolytic solution, wherein the inorganic solid electrolyte is in the form of a membrane or layer densified enough to have water impermeability, and the porous substrate has a thickness of 100 to 1,800 μm. According to the secondary battery of the present invention, the thickness and resistance of the ceramic separator are decreased without concern for reduced strength, and a reduction in energy density and an increase in internal resistance are effectively prevented.

Provided is a secondary battery including a hydroxide-ion-conductive ceramic separator. The secondary battery includes a positive electrode; a negative electrode; an alkaline electrolytic solution; a ceramic separator that is composed of a hydroxide-ion-conductive inorganic solid electrolyte and separates the positive electrode from the negative electrode; a porous substrate disposed on at least one surface of the ceramic separator; and a container accommodating at least the negative electrode and the alkaline electrolytic solution, wherein the inorganic solid electrolyte is in the form of a membrane or layer densified enough to have water impermeability, and the porous substrate has a thickness of 100 to 1,800 μm. According to the secondary battery of the present invention, the thickness and resistance of the ceramic separator are decreased without concern for reduced strength, and a reduction in energy density and an increase in internal resistance are effectively prevented.

The disclosure relates to a method for the fabrication of a thin-film solid-state battery with Ni(OH).sub.2 electrode, battery cell, and battery. One example embodiment is a method for fabricating a thin-film solid-state battery cell on a substrate comprising a first current collector layer. The method includes depositing above the first current collector layer a first electrode layer. The first electrode layer is a nanoporous composite layer that includes a plurality of pores having pore walls. The first electrode layer includes a mixture of a dielectric material and an active electrode material. The method also includes depositing above the first electrode layer a porous dielectric layer. The method further includes depositing directly on the porous dielectric layer a second electrode layer. Depositing the second electrode layer includes depositing a porous Ni(OH).sub.2 layer using an electrochemical deposition process.

The disclosure relates to a method for the fabrication of a thin-film solid-state battery with Ni(OH).sub.2 electrode, battery cell, and battery. One example embodiment is a method for fabricating a thin-film solid-state battery cell on a substrate comprising a first current collector layer. The method includes depositing above the first current collector layer a first electrode layer. The first electrode layer is a nanoporous composite layer that includes a plurality of pores having pore walls. The first electrode layer includes a mixture of a dielectric material and an active electrode material. The method also includes depositing above the first electrode layer a porous dielectric layer. The method further includes depositing directly on the porous dielectric layer a second electrode layer. Depositing the second electrode layer includes depositing a porous Ni(OH).sub.2 layer using an electrochemical deposition process.

A lithium secondary battery includes a positive electrode, a negative electrode, and an electrolyte solution. The positive electrode contains a positive electrode active material including element M2 incorporated in a crystal structure in a surface layer area of a complex oxide, the oxide including the element M1 and being represented by the following formula (1), M2 being different from M1. The element M2 is at least one kind selected from the group consisting of magnesium Mg, calcium Ca, titanium Ti, zirconium Zr, sulfur S, fluorine F, iron Fe, copper Cu, boron B, aluminum Al, phosphorus P, carbon C, manganese Mn, nickel Ni, and cobalt Co.
Li.sub.1+a(Mn.sub.bCo.sub.cNi.sub.1−b−c).sub.1−aM1.sub.dO.sub.2−e  (1) M1 is at least one kind of aluminum, magnesium, zirconium, titanium, barium Ba, boron, silicon Si, and iron, a satisfies 0<a<0.25, b satisfies 0.5≦b<0.7, c satisfies 0≦c<1−b, d satisfies 0.01≦d≦0.2, and e satisfies 0≦e≦1.

Disclosed is a cathode active material for secondary batteries in which a carboxymethyl cellulose derivative is coated on surfaces of particles of a lithium transition metal oxide having the formula Li.sub.xM.sub.yO.sub.2 where M: Ni.sub.aMn.sub.bCo.sub.c wherein 0≦a≦0.9, 0≦b≦0.9, 0≦c≦0.5, and 0.85≦a+b+c≦1.05 and x+y=2, wherein 0.95≦x≦1.15.

A coated nickel hydroxide powder that has a cobalt compound coating having improved uniformity and adhesion properties on the surface of particles thereof and is therefore suitable for a positive electrode active material of an alkaline secondary battery is obtained by coating the surface of nickel hydroxide particles with a cobalt compound, and has a transmittance ratio of 30% or higher as determined by (A−B.sub.max)/(B.sub.0−B.sub.max). The transmittance A (coated nickel hydroxide powder), the transmittance B.sub.0 (nickel hydroxide powder), or the transmittance B.sub.max (nickel hydroxide powder and cobalt compound containing cobalt in an amount corresponding to the amount of cobalt contained in the coating) can be determined by measuring the transmittance of a tubular transparent cell after shaking the tightly-closed transparent cell containing each powder for a certain time and then taking the contents out of the transparent cell.

A coated nickel hydroxide powder that has a cobalt compound coating having improved uniformity and adhesion properties on the surface of particles thereof and is therefore suitable for a positive electrode active material of an alkaline secondary battery is obtained by coating the surface of nickel hydroxide particles with a cobalt compound, and has a transmittance ratio of 30% or higher as determined by (A−B.sub.max)/(B.sub.0−B.sub.max). The transmittance A (coated nickel hydroxide powder), the transmittance B.sub.0 (nickel hydroxide powder), or the transmittance B.sub.max (nickel hydroxide powder and cobalt compound containing cobalt in an amount corresponding to the amount of cobalt contained in the coating) can be determined by measuring the transmittance of a tubular transparent cell after shaking the tightly-closed transparent cell containing each powder for a certain time and then taking the contents out of the transparent cell.