A cathode composition includes a lithium transition metal oxide having the formula Li.sub.p□.sub.qNi.sub.xMn.sub.yCo.sub.zO.sub.2, where □ represents assumed vacancy content, p+q+x+y+z=2, 0.05<q<0.15, 0.8<p<1.02, 0.05<x<0.45, 0.05<y<0.6, 0.05<z<0.6, and 0.14<p*x<0.34. The lithium transition metal oxide has an O3 type structure.

A method for producing porous graphite capable of realizing higher durability, output and capacity, and porous graphite. A carbon member having microvoids is obtained by a dealloying step for selectively eluting other non-carbon main components into a metal bath by immersing a carbon-containing material, composed of a compound including carbon or an alloy or non-equilibrium alloy, in the metal bath, wherein the metal bath has a solidifying point lower than the melting point of the carbon-containing material, and is controlled to a temperature lower than the minimum value of a liquidus temperature within a composition fluctuation range extending from the carbon-containing material to carbon by reducing the other non-carbon main components. The carbon member obtained in the dealloying step is graphitized by heating in a graphitization step. The carbon member graphitized in the graphitization step is subjected to activation treatment by an activation step.

A negative electrode active material according to one embodiment includes a titanium oxide compound having a crystal structure of monoclinic system titanium dioxide. The titanium oxide compound is modified by at least one kind of ion selected from the group consisting of an alkali metal cation, an alkali earth metal cation, a transition metal cation, a sulfide ion, a sulfuric acid ion and a chloride ion.

The present invention relates to a method for producing titanium oxide particles, comprising a step of producing a mixed solution by mixing a hydrolysis product of a titanium alkoxide or a titanium metal salt and a compound having a five-membered ring containing nitrogen and a step of generating titanium oxide fine particles by heating and pressurizing the mixed solution, titanium oxide particles produced by the same production method, a dispersion solution of titanium oxide particles produced using the same titanium oxide particles, titanium oxide paste, a titanium oxide film, and a dye-sensitized solar cell.

A cathode active material contains a secondary particle containing or consisting of a group of a plurality of primary particles. At least some of the primary particles disposed on the surface of the secondary particle include first primary particle in the form of flakes having a pair of first crystal faces facing toward each other. The first crystal faces are arranged in a radial direction, ends of the first crystal faces pair are provided with a plurality of crystal faces different from the first crystal faces to connect the ends of the first crystal faces pair. Longitudinal cross-sections of the first primary particle contain a pair of first crystal faces spaced apart from each other. Second and third crystal faces are disposed in the outermost surface of the secondary particle to be connected to each other at an angle.

To provide a process for producing a cathode active material capable of obtaining a lithium ion secondary battery which has a high discharge capacity and a high initial efficiency, a cathode active material, a positive electrode for a lithium ion secondary battery, and a lithium ion secondary battery. A process for producing a cathode active material, which comprises a mixing step of mixing a lithium compound, an alkali metal compound other than Li, and a transition metal-containing compound containing at least Ni and Mn to obtain a mixture, a step of firing the mixture at a temperature of from 900 to 1,100° C. to obtain a first lithium-containing composite oxide containing the alkali metal other than Li, and a step of removing the alkali metal other than Li from the first lithium-containing composite oxide to obtain a second lithium-containing composite oxide represented by the following formula:
aLi(Li.sub.1/3Mn.sub.2/3)O.sub.2.Math.(1−a)LiMO.sub.2
wherein 0<a<1, and M is an element containing at least Ni and Mn.

Provided is a piezoelectric material filler including alkali niobate compound particles having a ratio (K/(Na+K)) of the number of moles of potassium to the total number of moles of sodium and potassium of 0.460 to 0.495 in terms of atoms and a ratio ((Li+Na+K)/Nb) of the total number of moles of alkali metal elements to the number of moles of niobium of 0.995 to 1.005 in terms of atoms. The present invention can provide a piezoelectric material filler having excellent piezoelectric properties, and a composite piezoelectric material including the piezoelectric material filler and a polymer matrix.

A solid electrolyte material according to an aspect of the present disclosure is represented by the following Compositional Formula (1):
Li.sub.6-3zY.sub.zX.sub.6
where, 0<z<2 is satisfied; and X represents Cl or Br.

An electrode for a secondary battery comprises a current collector; and an active material-containing layer has active materials which comprise titanium-containing composite oxide having an orthorhombic crystal structure and represented by a general formula Li.sub.2+aM1.sub.2−bTi.sub.6−cM2.sub.dO.sub.14+δ; wherein the active material-containing layer has intensity ratio Ia/Ib in an X-ray diffraction pattern of the active material-containing layer, the Ia and the Ib are obtained by powder X-ray diffraction method using Cu-Kα ray, the intensity ratio is within a range of 0.5≤Ia/Ib≤2, the Ia is the strongest intensity of a diffraction peak among diffraction peaks appearing within a range of 42°≤2θ≤44°, and the Ib is the strongest intensity of a diffraction peak among diffraction peaks appearing within a range of 44°<2θ≤48°. (M1 is at least one selected from the group consisting of Sr, Ba, Ca, Mg, Na, Cs, Rb and K, M2 is at least one selected from the group consisting of Zr, Sn, V, Nb, Ta, Mo, W, Y, Fe, Co, Cr, Mn, Ni and Al a is within a range of 0≤a≤6 b is within a range of 0≤b<2 c is within a range of 0≤c<6 d is within a range of 0≤d<6 δ is within a range of −0.5≤δ≤0.5.)

Provided is a chlorine-containing positive electrode active material that can impart excellent high-temperature storage characteristic to a lithium ion secondary battery. The positive electrode active material disclosed herein includes 0.1% by mass or more and 3% by mass or less of Cl. Further, in the positive electrode active material disclosed herein, the ratio of a peak intensity of a (003) plane to a peak intensity of a (104) plane in Miller indexes hlk that is determined by powder X-ray diffraction is 0.8 or more and 1.5 or less.