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.

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.

Compounds, powders, and cathode active materials that can be used in lithium ion batteries are described herein. Methods of making such compounds, powders, and cathode active materials are described.

Acidified metal oxides combined with non-acidified metal oxides used as a battery electrode active material.

A technique for improving the performance of a secondary battery is provided. A secondary battery according to an embodiment includes a first electrode, a second electrode, a first layer disposed on the first electrode, and including a first n-type oxide semiconductor, a second layer disposed on the first layer and including a second n-type oxide semiconductor material and a first insulating material, a third layer disposed on the second layer and including tantalum oxide, and a fourth layer disposed on the third layer and including a second insulating material.

Provided is a sodium secondary battery that has visible light transparency and is excellent in flexibility. A sodium secondary battery includes: a positive electrode film that contains a material formed on a flexible transparent film substrate, the material being capable of intercalating and deintercalating sodium ions; a transparent electrolyte having sodium ion conductivity; and a negative electrode film that if formed of a material formed on a flexible transparent film substrate, the material being capable of dissolving and depositing sodium or intercalating and deintercalating sodium ions. When the positive electrode film contains a sodium source, the negative electrode film is made to have a thickness of 30 nm to 200 nm by using, as a negative electrode material, any of tin oxide, silicon oxide, titanium oxide, tungsten oxide, niobium oxide, molybdenum oxide, metal phosphide, metal sulfide, metal nitride, metal fluoride, or metal titanium composite oxide.

The present disclosure relates to a positive active material for a lithium rechargeable battery and a lithium rechargeable battery including the same, which include a first compound represented by Chemical Formula 1 and a second compound represented by Chemical Formula 2, and a content of the first compound is 65 wt % or more based of the positive active material of 100 wt %.

Li.sub.a1Ni.sub.b1Co.sub.c1Mn.sub.d1M1.sub.e1M2.sub.f1O.sub.2-f1   [Chemical Formula 1]

Li.sub.a2Ni.sub.b2Co.sub.c2Mn.sub.d2M3.sub.e2M4.sub.f2O.sub.2-f2   [Chemical Formula 2] Chemical Composition 1 and 2 of each composition and molar ratio is as defined in the specification. Each composition and molar ratio of Chemical Formula 1 and 2 is as defined in the specification.

Compounds, powders, and cathode active materials that can be used in lithium ion batteries are described herein. Methods of making such compounds, powders, and cathode active materials are described.

A method of synthesizing an electrode material for lithium ion batteries from Fe.sub.3O.sub.4 nanoparticles and multiwalled carbon nanotubes (MWNTs) to yield (Fe.sub.3O.sub.4-NWNTs) composite heterostructures. The method includes linking the Fe.sub.3O.sub.4 nanoparticles and multiwalled carbon nanotubes using a π-π interaction synthesis process to yield the composite heterostructure electrode material. Since Fe.sub.3O.sub.4 has an intermediate voltage, it can be considered an anode (when paired with a higher voltage material) or a cathode (when paired with a lower voltage material).

An anode for an energy storage device includes a current collector having a metal oxide layer. A continuous porous lithium storage layer overlays the metal oxide layer, and a first supplemental layer overlays the continuous porous lithium storage layer. The continuous porous lithium storage layer may be substantially free of nanostructures. The continuous lithium storage layer may include amorphous silicon deposited by a PECVD process. The first supplemental layer includes silicon nitride, silicon dioxide, or silicon oxynitride. The anode may further include a second supplemental layer overlaying the first supplemental layer.