A positive electrode active material particle with little deterioration is provided. A power storage device with little deterioration is provided. A highly safe power storage device is provided. The positive electrode active material particle includes a first crystal grain, a second crystal grain, and a crystal grain boundary positioned between the crystal grain and the second crystal grain; the first crystal grain and the second crystal grain include lithium, a transition metal, and oxygen; the crystal grain boundary includes magnesium and oxygen; and the positive electrode active material particle includes a region where the ratio of the atomic concentration of magnesium in the crystal grain boundary to the atomic concentration of the transition metal in first crystal grain and the second crystal grain is greater than or equal to 0.010 and less than or equal to 0.50.

A lithium-replenishing additive is provided. The lithium-replenishing additive includes a lithium-rich-material core and a shell layer disposed at the lithium-rich-material core. The lithium-rich-material core is made of a lithium-rich material with an average chemical formula of aNi.sub.xM.sub.yO.sub.2 .Math.bLi.sub.2O, where 0.95≤x≤1, 0.01≤y≤0.05, 1≤z≤1.15, 0.8≤a≤1.1, 0.8≤b≤1.1, and the M includes one or more of copper (Cu), cobalt (Co), aluminum (Al), titanium (Ti), vanadium (V), zirconium (Zr), or iron (Fe). The shell layer includes a polymer layer. A preparing method of a lithium-replenishing additive and a lithium secondary battery are further provided.

This non-aqueous electrolyte secondary battery comprises: a separator that has an adhesive on at least one surface thereof; and an electrode that has a core and an electrode mix layer, and that is configured so that the electrode mix layer abuts the adhesive. The electrode mix layer is configured so that the density, in the thickness-direction, of a porous body increases from the core towards the adhesive.

A secondary battery that includes an electrode assembly; an exterior body defining a housing space that houses the electrode assembly; a positive electrode terminal that includes a first metal layer made of nickel and a second metal layer made of a metal other than nickel, the first metal layer of the positive electrode terminal is exposed from the exterior body, and the first metal layer has a fixing face; and an insulating material positioned so as to fix the fixing face of the first metal layer to an inner wall of the exterior body, and the insulating material abuts against a face of the positive electrode terminal other than the fixing face of the first metal layer.

A cobalt-free layered positive electrode material, a preparation method thereof, and a lithium-ion battery are provided. The method includes: preparing a layered lithium nickel manganese oxide matrix material; mixing the layered lithium nickel manganese oxide matrix material with a coating agent to obtain a first mixed material; and forming a coating layer on a surface of the layered lithium nickel manganese oxide matrix material by performing a first sintering treatment on the first mixed material to obtain the cobalt-free layered positive electrode material. The coating agent includes a first coating agent including ceramic oxide, and a second coating agent including at least one of phosphate and silicate.

A mixed powder for an all-solid-state lithium-ion battery, which is composed of a positive electrode active material for a lithium-ion battery and a solid electrolyte, wherein the positive electrode active material for a lithium-ion battery is composed of particles containing crystals of a lithium metal composite oxide, and the lithium metal composite oxide has a layered structure and contains at least Li and a transition metal, wherein the positive electrode active material for a lithium-ion battery has a particle diameter distribution that satisfies the following Formula (1), and wherein the solid electrolyte has a particle diameter distribution that satisfies the following Formula (2):

[00001]$\left(\text{D90-D10}\right)/\text{D50}\le \text{1}\text{.5}$

[00002]$\left(\text{D90-D10}\right)/\text{D50}\le 2.0$

A positive electrode material and a preparation method therefor, a lithium-ion battery, and an electric vehicle. The positive electrode material comprises: matrix particles, materials forming the matrix particles comprising at least one of a lithium-rich manganese-based material, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, lithium manganate, lithium nickel cobalt manganese aluminate, and lithium nickel manganate; and a housing, the housing covering at least a portion of the outer surfaces of the matrix particles.

What is claimed is a positive electrode active material for an all-solid-state lithium-ion battery composed of particles containing crystals of a lithium metal composite oxide,

wherein the lithium metal composite oxide has a layered structure and contains at least Li and a transition metal, and wherein, in the particles, in pore physical properties obtained from nitrogen adsorption isotherm measurement and nitrogen desorption isotherm measurement at a liquid nitrogen temperature, the total pore volume obtained from a nitrogen adsorption amount when the relative pressure (p/p.sub.0) of an adsorption isotherm is 0.99 is less than 0.0035 cm.sup.3/g.

A class of compositions that are inclusive of a lithium metal oxide or oxyfluoride compound having a general formula: LiTM[n]OF where TM[n] represents a number of transition metal species inclusive of transitional metal species differentiated by charge or d.sup.0 electron shell conformation, with [n] being at least 4 of said transitional metal species, and wherein said lithium metal oxide or oxyfluoride has a cation-disordered rocksalt (DRX) structure and a mitigated SRO via a high entropy DRX design strategy. Also featured is a method of synthesizing the high entropy DRX lithium metal oxide or oxyfluoride compounds, as well as usage of the same in Li-ion batteries, with particular utility in cathodes of such Li-ion batteries.

Secondary batteries using lithium cobalt oxide as positive electrode active materials have a problem of a decrease in battery capacity due to repeated charging/discharging, for example. A positive electrode active material particle which hardly deteriorates is provided. In a first step, a container in which a lithium oxide and a fluoride are set is placed in a heating furnace, and in a second step, the inside of the heating furnace is heated in an atmosphere containing oxygen. The heating temperature of the second step is from 750° C. to 950° C., inclusive. By the manufacturing method, fluorine can be contained in the positive electrode active material particle to increase the wettability of the surface of the positive electrode active material so that the surface of the positive electrode active material is homogenized and planarized. The crystal structure of the thus manufactured positive electrode active material is unlikely to be broken in repeated high-voltage charging/discharging. Thus, secondary batteries using the positive electrode active material having such a feature have greatly improved cycle characteristics.