The present invention provides a sulfur-modified polyacrylonitrile, which has a content of sulfur of from 30 mass % to 50 mass %, and satisfies the expression: 4,500<140×x−y<5,200 when the content (mass %) of sulfur is represented by “x”, and an average CT value of the sulfur-modified polyacrylonitrile in X-ray CT is represented by “y”.

Disclosed is an electrode active material that has a large charge discharge capacity, a high initial efficiency, as well as excellent cycle characteristics and rate characteristics and is favorably used in a non-aqueous electrolyte secondary battery. An organo sulfur-based electrode active material contains sodium and potassium in a total amount of 100 ppm by mass to 1000 ppm by mass; an electrode for use in a secondary battery, the electrode containing the organo sulfur-based electrode active material as an electrode active material; and a non-aqueous electrolyte secondary battery including the electrode. Preferably, the organo sulfur-based electrode active material further contains iron in an amount of 1 ppm by mass to 20 ppm by mass. Preferably, the organo sulfur-based electrode active material is sulfur-modified polyacrylonitrile, and the amount of sulfur in the organo sulfur-based electrode active material is 25 mass % to 60 mass %.

The cathode active material for a lithium secondary battery according to embodiments of the present invention includes a lithium-transition metal composite oxide particle including a plurality of primary particles, and the lithium-transition metal composite oxide particle includes a lithium-sulfur-containing portion formed between the primary particles. Thereby, it is possible to improve life-span properties and capacity properties by preventing the layer structure deformation of the primary particles and removing residual lithium.

The cathode active material for a lithium secondary battery according to embodiments of the present invention includes a lithium-transition metal composite oxide particle including a plurality of primary particles, and the lithium-transition metal composite oxide particle includes a lithium-sulfur-containing portion formed between the primary particles. Thereby, it is possible to improve life-span properties and capacity properties by preventing the layer structure deformation of the primary particles and removing residual lithium.

A carbon-sulfur composite including a carbonized metal-organic framework (MOF); and a sulfur compound introduced to at least a part of an outside surface and an inside of the carbonized metal-organic framework, wherein the carbonized metal-organic framework has a specific surface area of 1000 m.sup.2/g to 4000 m.sup.2/g, and the carbonized metal-organic framework has a pore volume of 0.1 cc/g to 10 cc/g, and a method for preparing the same.

A carbon-sulfur composite including a carbonized metal-organic framework (MOF); and a sulfur compound introduced to at least a part of an outside surface and an inside of the carbonized metal-organic framework, wherein the carbonized metal-organic framework has a specific surface area of 1000 m.sup.2/g to 4000 m.sup.2/g, and the carbonized metal-organic framework has a pore volume of 0.1 cc/g to 10 cc/g, and a method for preparing the same.

A cathode active material for a lithium secondary battery includes a lithium metal oxide particle, and an organic poly-phosphate or an organic poly-phosphonate formed on at least portion of a surface of the lithium metal oxide particle. Chemical stability of the lithium metal oxide particle may be improved and surface residues may be reduced by the organic poly-phosphate or the organic poly-phosphonate.

Provided is a secondary battery, comprising a positive electrode, the positive electrode comprises a positive electrode material layer, and the positive electrode material layer comprises a positive electrode active material and a compound represented by structural formula I: ##STR00001## the positive electrode active material includes one or more of the compounds represented by Li.sub.1+xNi.sub.aCo.sub.bM′.sub.1−a−bO.sub.2−yA.sub.y and Li.sub.1+zMn.sub.cL.sub.2−cO.sub.4−dB.sub.d; the positive electrode material layer meets the following requirements:
0.05≤p.Math.u/v≤15 wherein, u is the percentage mass content of element phosphorus in the positive electrode material layer, and the unit is wt %; v is the percentage mass content of element M in the positive electrode material layer, element M is selected from one or two of Mn and Al, and the unit is wt %; p is the surface density of one single surface of the positive electrode material layer, and the unit is mg/cm.sup.2.

Provided is a secondary battery, comprising a positive electrode, the positive electrode comprises a positive electrode material layer, and the positive electrode material layer comprises a positive electrode active material and a compound represented by structural formula I: ##STR00001## the positive electrode active material includes one or more of the compounds represented by Li.sub.1+xNi.sub.aCo.sub.bM′.sub.1−a−bO.sub.2−yA.sub.y and Li.sub.1+zMn.sub.cL.sub.2−cO.sub.4−dB.sub.d; the positive electrode material layer meets the following requirements:
0.05≤p.Math.u/v≤15 wherein, u is the percentage mass content of element phosphorus in the positive electrode material layer, and the unit is wt %; v is the percentage mass content of element M in the positive electrode material layer, element M is selected from one or two of Mn and Al, and the unit is wt %; p is the surface density of one single surface of the positive electrode material layer, and the unit is mg/cm.sup.2.

A coated hybrid electrode for a composite solid-state battery cell is disclosed. Systems and methods are further provided for forming an electrolyte coating including a solid ionically conductive polymer material in the coated hybrid electrode. In one example, the coated hybrid electrode can include an anode material coating, the solid polymer electrolyte coating, and a cathode material coating, such that the solid polymer electrolyte coating can function as a separator coating between the anode material coating and the cathode material coating, thus eliminating a need for a conventional battery separator. In some examples, a slurry-based coating process can be utilized for forming the solid polymer electrolyte coating. As such, the solid polymer electrolyte coating can be mechanically robust with uniform thickness. Further, a battery cell can be formed by utilizing a sub-assembly stacking technique to provide battery cell stiffness and increase precision and accuracy of coating.