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.

There is provided a separator for an electricity storage device, comprising a polyolefin resin microporous membrane and an inorganic porous layer arranged on at least one surface of the polyolefin resin microporous membrane, wherein the inorganic porous layer has at least one selected from the group consisting of (i) covalent bonding between inorganic particles, (ii) covalent bonding between resin binders, and (iii) covalent bonding between an inorganic particle and a resin binder, and the polyolefin resin microporous membrane comprises a silane graft-modified polyolefin, and a silane crosslinking reaction in the silane graft-modified polyolefin is initiated when the separator for an electricity storage device is brought into contact with an electrolyte solution.

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.

A doped electrode may be manufactured by doping an active material included in an electrode with an alkali metal in a dope solution containing a first aprotic solvent and an alkali metal salt. The doped electrode may be cleaned with a cleaning solution containing a second aprotic solvent that has a boiling point lower than that of the first aprotic solvent. The cleaning solution may be controlled such that a content ratio of the first aprotic solvent in the cleaning solution is 8 vol % or lower.

A secondary battery includes a positive electrode, a negative electrode, and an electrolytic solution. The positive electrode includes a positive electrode active material layer. The positive electrode active material layer includes a lithium-nickel composite oxide of a layered rock-salt type.

A miniature electrochemical cell having a volume of less than 0.5 cc is described. The cell has a casing of first and second ceramic substrates that are hermetically secured to each other to provide an internal space housing an electrode assembly. First and second conductive pathways extend through the ceramic substrates. The pathways have respective inner surfaces that are conductively connected to the respective anode and cathode current collectors and respective outer surfaces that provide for connection to a load. An electrolyte in the internal space of the housing activates the electrode assembly.

An integrated energy storage component that includes a substrate supporting a contoured layer having a region with a contoured surface such as elongated pores. A stack structure is provided conformally over the contoured surface of this region. The stack is a single or repeated instance of MOIM layers, or MIOM layers, the M layers being metal layers, or a quasi-metal such as TiN, the O layers being oxide layers containing ions, and the I layer being an ionic dielectric. The regions having a contoured surface may be formed of porous anodized alumina.

A doping system is configured to dope an active material included in an electrode with an alkali metal. The doping system includes a doping bath, a conveyor unit, a connection unit, and a drying unit. The doping bath is configured to store a solution containing alkali metal ion and a counter electrode unit. The conveyor unit is configured to convey the electrode along a path that passes through the doping bath. The connection unit includes an electrically conductive electric power supply roller that contacts the electrode, and is configured to couple the electrode to the counter electrode unit. The drying unit is configured to spray a gas onto the electrode that passes through the doping bath and is being conveyed to the electric power supply roller.

The present invention relates to a method for preparing an electrode comprising a metal substrate, vertically aligned carbon nanotubes and a metal oxide deposited over the entire length of said vertically aligned carbon nanotubes, said method comprising the following consecutive steps: (a) synthesizing, on a metal substrate, a mat of vertically aligned carbon nanotubes; (b) electrochemically depositing the metal oxide on said carbon nanotubes from an electrolytic solution comprising at least one precursor of said metal oxide and at least one nitrate, said electrochemical deposition being carried out by a chronopotentiometry technique. The present invention also relates to the electrode thus prepared and to the uses thereof.

To provide a secondary battery in which a side reaction does not easily occur at an interface between a positive electrode active material and a solid electrolyte, an interface between the positive electrode active material and a positive electrode current collector, or the like even when charge and discharge are repeated. In one embodiment of the present invention, a buffer layer or a protective layer is provided on a current collector surface or between a current collector layer and an active material layer to prevent deterioration such as oxidation of the current collector. As the buffer layer or the protective layer, it is possible to use a titanium compound such as titanium oxide, titanium oxide in which nitrogen is substituted for part of oxygen, titanium nitride, titanium nitride in which oxygen is substituted for part of nitrogen, or titanium oxynitride (TiO.sub.xN.sub.y, where 0<x<2 and 0<y<1). Titanium nitride is particularly preferable because it has high conductivity and has a high capability of inhibiting oxidation.