A negative active material for a rechargeable lithium battery includes a carbon-based active material including highly crystalline natural graphite and artificial graphite. The carbon-based active material has a peak intensity ratio (P2/P4) of about 0.3 to about 0.4, wherein P2 refers to the 101 peak of a rhombohedral crystal grain and P4 refers to the 101 peak of a hexagonal crystal grain, as measured by X-ray diffraction.

A storage device having excellent cycle lifetime, an electrode used in this storage device, and a production method of the electrode are provided. An electrode comprising an active material and a conductive carbon including oxidized carbon. A surface of the active material is covered by the conductive carbon. A Raman spectrum of the active material covered by the conductive carbon includes a peak intensity (a) derived from the active material and a peak intensity (b) of D-band derived from the conductive carbon. A peak intensity ratio (b)/(a) between the peak intensity (a) and the peak intensity (b) is 0.25 or more.

A preparation method of a composite anode material of micrometer-sized carbon-coated silicon and carbon includes: subjecting micrometer-sized silicon particles to a chemical vapor deposition reaction under a gas atmosphere containing carbon to obtain carbon-coated first micrometer-sized silicon particles; dispersing the carbon-coated first micrometer-sized silicon particles in a first mixed solvent to obtain a dispersed solution; adding alkali into the dispersed solution and heating the dispersed solution to obtain carbon-coated second micrometer-sized silicon particles; dispersing the carbon-coated second micrometer-sized silicon particles and graphene oxide in a second mixed solvent that are subjected to a hydrothermal reaction to obtain a composite hydrogel of reduced graphene oxide, silicon, and carbon; and heating the hydrogel to obtain the composite anode material.

Provided are a cobalt-free positive electrode material for a lithium ion battery, a preparation method therefor and a lithium ion battery. The method for preparing the cobalt-free positive electrode material for the lithium ion battery comprises: mixing lithium nickel manganese oxide with sulfate, so as to obtain a first mixture; and reacting the first mixture at a predetermined temperature, so as to obtain the cobalt-free positive electrode material. The cobalt-free positive electrode material comprises lithium nickel manganese oxide and a cladding layer of an outer surface thereof, and the cladding layer comprises lithium sulphate. The lithium ion battery comprises the cobalt-free positive electrode material. The cobalt-free positive electrode material has a relatively high electrical performance and a relatively low alkali content.

The present invention provides a binder for a secondary battery that can reduce the initial resistance value of the secondary battery. A binder for a secondary battery comprising a polymer compound, wherein the polymer compound contains repeating units represented by formulae (1), (2), and (3):

##STR00001## in formula (1), R.sup.1 is a hydrogen atom or a methyl group, and M is a hydrogen atom or an alkali metal atom; and in formula (3), R.sup.2 is a hydrogen atom or a methyl group; and when a total ratio of repeating units constituting the polymer compound is taken as 100 mol %, a total ratio of the repeating unit represented by formula (3) is less than 2 mol %.

The present invention provides a binder for a secondary battery that can reduce the initial resistance value of the secondary battery. A binder for a secondary battery comprising a polymer compound, wherein the polymer compound contains repeating units represented by formulae (1), (2), and (3):

##STR00001## in formula (1), R.sup.1 is a hydrogen atom or a methyl group, and M is a hydrogen atom or an alkali metal atom; and in formula (3), R.sup.2 is a hydrogen atom or a methyl group; and when a total ratio of repeating units constituting the polymer compound is taken as 100 mol %, a total ratio of the repeating unit represented by formula (3) is less than 2 mol %.

A secondary battery with excellent cycle performance is provided. The secondary battery is an all-solid-state battery including a positive electrode current collector layer, a base film, a positive electrode active material layer, a buffer layer, and a solid electrolyte layer. The base film contains titanium nitride. The positive electrode active material layer contains lithium cobalt oxide. The buffer layer contains titanium oxide. The solid electrolyte layer contains a titanium compound. By using titanium oxide for the buffer layer, a side reaction between the positive electrode active material layer and the solid electrolyte layer can be suppressed, and cycle performance can be improved.

Embodiments of the present invention relate to a cathode active material, a method for manufacturing the same, and a lithium secondary battery including the same.

According to an embodiment, a cathode active material can be provided, the cathode active material comprising: a lithium metal oxide including a core and a shell disposed on a surface of the core; and a coating layer disposed on a surface of the lithium metal oxide, wherein a c value that satisfies Equation 1 and is in a range of 0.3 to 0.7, and the core and the shell have a layered crystalline structure.

c=b/a  [Equation 1]

(in Equation 1, a is a peak at 530 to 533 eV and b is a peak at 528 to 531 eV in an XPS spectrum of the coating layer)

Provided are a positive electrode active material for a lithium secondary battery, a method of preparing the same, and a lithium secondary battery including the same.

According to an exemplary embodiment, a positive electrode active material for a lithium secondary battery which includes lithium metal oxide particles and a coating layer placed on at least a part of a surface of the lithium metal oxide particles may be provided, wherein the coating layer includes B, LiOH, Li.sub.2CO.sub.3, and Li.sub.2SO.sub.4.

Provided are a positive electrode active material for a lithium secondary battery, a method of preparing the same, and a lithium secondary battery including the same.

According to an exemplary embodiment, a positive electrode active material for a lithium secondary battery which includes lithium metal oxide particles and a coating layer placed on at least a part of a surface of the lithium metal oxide particles may be provided, wherein the coating layer includes B, LiOH, Li.sub.2CO.sub.3, and Li.sub.2SO.sub.4.