A lithium-sulfur accumulator comprising at least one electrochemical cell comprising a positive electrode comprising, as active material, at least one sulfur-containing material, a negative electrode and an electrolyte conducting lithium ions disposed between the negative electrode and the positive electrode, wherein the negative electrode comprises, as active material, a lithium and calcium alloy, wherein the calcium is present in the alloy to the extent of 2% to 34% atomic.

A negative electrode active material including a core, an intermediate layer on a surface of the core, and a shell layer on a surface of the intermediate layer, wherein the core includes a silicon oxide of SiO.sub.x (0<x<2); the intermediate layer includes a lithium silicate, the shell layer includes lithium fluoride (LiF) and the intermediate layer is present in an amount of 5 wt %-15 wt % based on a total weight of the negative electrode active material. Also, a method for preparing the negative electrode active material, and a negative electrode and lithium secondary battery including the same. The negative electrode active material provides excellent initial efficiency and life characteristics.

A negative electrode active material including a core, an intermediate layer on a surface of the core, and a shell layer on a surface of the intermediate layer, wherein the core includes a silicon oxide of SiO.sub.x (0<x<2); the intermediate layer includes a lithium silicate, the shell layer includes lithium fluoride (LiF) and the intermediate layer is present in an amount of 5 wt %-15 wt % based on a total weight of the negative electrode active material. Also, a method for preparing the negative electrode active material, and a negative electrode and lithium secondary battery including the same. The negative electrode active material provides excellent initial efficiency and life characteristics.

Provided is a method for producing an electrode active material capable of forming a non-aqueous secondary battery with superior durability and output characteristics. The method for producing an electrode active material for a non-aqueous secondary battery includes contacting a dispersion containing graphene and a dispersion medium with alkali-metal-transition-metal composite oxide particles, and the dispersion has a dispersibility index of 0.25 or more.

A positive electrode active material contains at least: fluorine in an amount not lower than 0.08 mass %; carbon in an amount not lower than 0.02 mass %; and lithium-metal composite oxide particles making up the remainder. The lithium-metal composite oxide particles contain nickel in an amount not lower than 60 mol % of the total amount of metallic elements. At least a partial amount of each of the fluorine and the carbon is present on surfaces of the lithium-metal composite oxide particles.

Methods of synthesizing few-layer two-dimensional (2D) Sb.sub.2S.sub.3 nanosheets using scalable chemical exfoliation are provided. The 2D Sb.sub.2S.sub.3 nanosheets can be developed as bi-functional anode materials in both lithium ion batteries and sodium ion batteries. The unique structural and functional features brought by 2D Sb.sub.2S.sub.3 nanosheets can offer short electron/ion diffusion paths and abundant active sites for surface redox reactions.

Methods of synthesizing few-layer two-dimensional (2D) Sb.sub.2S.sub.3 nanosheets using scalable chemical exfoliation are provided. The 2D Sb.sub.2S.sub.3 nanosheets can be developed as bi-functional anode materials in both lithium ion batteries and sodium ion batteries. The unique structural and functional features brought by 2D Sb.sub.2S.sub.3 nanosheets can offer short electron/ion diffusion paths and abundant active sites for surface redox reactions.

A positive electrode material for lithium ion secondary batteries is provided, wherein a ratio (A/B) of an oil absorption amount (A) of powder per unit mass of the material, which is measured using N-methyl-2-pyrrolidone, to a void volume (B) of powder per unit mass of the material is 0.30 or more and 0.85 or less, and a ratio (C/D) of a powder density (C) of the material, which is measured in a powder pressure test at a pressure of 4.5 MPa, to an initial powder density (D) of the material is 1.3 or more and 1.7 or less.

A lithium ion secondary battery includes: a positive electrode having a positive electrode active material layer on a surface of a positive electrode collector; a negative electrode a having a negative electrode active material layer on a surface of a negative electrode collector; and a nonaqueous electrolyte. The positive electrode, the negative electrode, and the nonaqueous electrolyte are accommodated in a battery case. The nonaqueous electrolyte contains γ-butyrolactone as a main component of a nonaqueous solvent. A monoalkyl sulfate ion-derived coat is formed on the surface of the positive electrode active material layer. A VC-derived coat is formed on the surface of the negative electrode active material layer.

A method for recycling waste lithium iron phosphate is by selective oxidation-reduction, to obtain recycled lithium iron phosphate, and a lithium ion battery. The method includes: primarily sintering waste lithium iron phosphate under a condition where a mild oxidizing gas is introduced; separating a lithium iron phosphate powder material; supplementing lithium and supplementing carbon to the lithium iron phosphate powder material and regulating the composition of the lithium iron phosphate powder material using a lithium source and a carbon source by secondary sintering to obtain recycled lithium iron phosphate, wherein the mild oxidizing gas is water vapor, CO2 gas, or a mixed gas thereof.