The present invention provides a sulfur-based positive electrode active material for use in a solid-state battery, comprising: 30-80 wt % of Li.sub.2S, 10-40 wt % of one or more second lithium compounds selected from LiI, LiBr, LiNO.sub.3, and LiNO.sub.2, and 0-30 wt % of a conductive carbon material; a method for preparing the sulfur-based positive electrode active material, a positive electrode including the sulfur-based positive electrode active material, and a solid-state battery including the positive electrode. The sulfur-based positive electrode active material and the positive electrode provide a high specific capacity and an increased discharge voltage.

A method for recycling a lithium iron phosphate positive plate with low energy consumption and low Al content, including: crushing a lithium iron phosphate positive plate to be recycled into a granular material with a particle size of 1-15 mm by using a crusher; heating the granular material obtained in step (1) to 350-500° C. in an atmosphere furnace in an inert atmosphere; and keeping the granular material at 350-500° C. for 0.5-2 h followed by cooling to a preset temperature to obtain a calcined product; grinding the calcined product obtained in step (2) by using a grinder to obtain a ground product with D50 larger than or equal to 50 μm; and classifying the ground product obtained in step (3) by using an air classifier to remove Al simple substance to obtain a recovered positive material with an Al content below 200 ppm.

A secondary battery includes a positive electrode, a negative electrode, and an electrolytic solution. The positive electrode includes a positive electrode current collector and a positive electrode active material layer. The positive electrode active material layer is provided on the positive electrode current collector and includes an electrically conductive substance. The electrically conductive substance includes electrically conductive supports and electrically conductive particles. The electrically conductive supports each include a carbon material. The electrically conductive particles are supported by the electrically conductive supports. The electrically conductive particles are primary particles that each include a lithium phosphate compound and have an average particle size of less than 35 nanometers.

A material for a negative electrode active material having capability of achieving excellent cycle performance while maintaining satisfactory initial efficiency (initial capacity), a production method for the material, a composition for a negative electrode, using the material, a negative electrode, and a secondary battery. A core-shell structure that includes the following components (A) and (B), and satisfies the following conditions (i) and (ii): (A): a core containing at least Si (silicon), O (oxygen) and C (carbon) as a constituent element, and containing crystalline carbon and non-crystalline carbon as a constituent; and (B): a shell encapsulating the core, and including a SiOC structure having a graphene layer, and (i): having an atomic composition represented by formula SiO.sub.xC.sub.y (0.5<x<1.8, 1.0<y<5.0), and (ii): having a predetermined value of less than 1.0×10.sup.5 Ω.Math.cm in specific resistance determined by powder resistance measurement.

Provided is a rechargeable alkali metal-sulfur cell comprising an anode active material layer, an electrolyte, and a cathode active material layer comprising multiple particulates, wherein at least one of the particulates comprises one or a plurality of sulfur-containing material particles being embraced or encapsulated by a thin layer of a conductive sulfonated elastomer composite having from 0.01% to 50% by weight of a conductive reinforcement material dispersed in a sulfonated elastomeric matrix material, wherein the conductive reinforcement material is selected from graphene sheets, carbon nanotubes, carbon nanofibers, metal nanowires, conductive polymer fibers, or a combination thereof and the composite has a recoverable tensile strain from 2% to 500%, a lithium ion conductivity from 10.sup.−7 S/cm to 5×10.sup.−2 S/cm, and a thickness from 0.5 nm to 10 μm. This battery exhibits an excellent combination of high sulfur content, high sulfur utilization efficiency, high energy density, and long cycle life.

Provided are a negative electrode composition including a sulfide-based inorganic solid electrolyte, a negative electrode active material containing a silicon atom or a tin atom, and a polymer, in which the polymer has substantially no adsorption capacity to the negative electrode active material and the sulfide-based inorganic solid electrolyte, a modulus of elasticity of the polymer measured in accordance with JIS K 7161 (2014) is 100 MPa or higher and 1000 MPa or lower, and in a case where a negative electrode active material layer is formed of the negative electrode composition, the polymer is contained in the negative electrode active material layer in a particle form, a negative electrode sheet for an all-solid state secondary battery, an all-solid state secondary battery, a method for manufacturing a negative electrode sheet for an all-solid state secondary battery, and a method for manufacturing an all-solid state secondary battery.

Provided are a negative electrode composition including a sulfide-based inorganic solid electrolyte, a negative electrode active material containing a silicon atom or a tin atom, and a polymer, in which the polymer has substantially no adsorption capacity to the negative electrode active material and the sulfide-based inorganic solid electrolyte, a modulus of elasticity of the polymer measured in accordance with JIS K 7161 (2014) is 100 MPa or higher and 1000 MPa or lower, and in a case where a negative electrode active material layer is formed of the negative electrode composition, the polymer is contained in the negative electrode active material layer in a particle form, a negative electrode sheet for an all-solid state secondary battery, an all-solid state secondary battery, a method for manufacturing a negative electrode sheet for an all-solid state secondary battery, and a method for manufacturing an all-solid state secondary battery.

A production method for producing a halide includes a heat-treatment step of heat-treating, in an inert gas atmosphere, a mixed material in which LiX and YZ.sub.3 are mixed, where X is an element selected from the group consisting of Cl, Br, and I, and Z is an element selected from the group consisting of Cl, Br, and I. In the heat-treatment step, the mixed material is heat-treated at higher than or equal to 200° C. and lower than or equal to 650° C.

Various methods and techniques for enhancing a silicon-containing anode for a battery cell are presented. The methods may include providing a silicon-containing anode having reversible electrochemical capabilities including a silicon-containing material and an anode material compatible with a lithium-ion battery chemistry having porous and conductive mechanical properties. The methods may also include enriching a surface layer of the silicon-containing anode with sodium ions to intersperse the sodium ions between silicon atoms of the silicon-containing matieral. The methods may also include displacing the sodium ions with potassium ions to form a comrpession layer in the silicon-containing anode. The potassium ions may place the silicon atoms of the silicon-containing material in a pre-compressive state to counteract internal stress exerted on the silicon-containing material.

Various methods and techniques for enhancing a silicon-containing anode for a battery cell are presented. The methods may include providing a silicon-containing anode having reversible electrochemical capabilities including a silicon-containing material and an anode material compatible with a lithium-ion battery chemistry having porous and conductive mechanical properties. The methods may also include enriching a surface layer of the silicon-containing anode with sodium ions to intersperse the sodium ions between silicon atoms of the silicon-containing matieral. The methods may also include displacing the sodium ions with potassium ions to form a comrpession layer in the silicon-containing anode. The potassium ions may place the silicon atoms of the silicon-containing material in a pre-compressive state to counteract internal stress exerted on the silicon-containing material.