ACTIVE MATERIAL AND METHOD FOR PRODUCING SAME, ELECTRODE MIXTURE, AND BATTERY

1 . An active material comprising:

a core portion made of an active material base material; and

a coating portion located on a surface of the core portion,

wherein the coating portion contains an element A comprising at least one selected from the group consisting of titanium (Ti), zirconium (Zr), tantalum (Ta), niobium (Nb), and aluminum (Al), and

the active material has two or more inflection points in a first-order derivative obtained with respect to a peak attributed to the element A, the first-order derivative being obtained based on a constituent element average intensity profile measured for the coating portion with use of an energy dispersive X-ray spectrometer.

2 . The active material according to claim 1 ,

wherein, when an interface between the core portion and the coating portion is defined as an origin, and at least inflection points P 1 and P 2 are present as the inflection points in an order from the origin in a thickness direction of the coating portion,

the inflection point P 1 is observed within 10 nm from the origin in the thickness direction of the coating portion.

3 . The active material according to claim 1 ,

wherein the coating portion contains lithium (Li) element, the element A, and oxygen (O) element.

4 . A method for producing an active material having: a core portion made of an active material base material; and a coating portion located on a surface of the core portion,

the method comprising:

a preparing step of preparing a dispersion liquid in which a powder constituting the core portion is dispersed in a liquid containing water; and

a mixing step of mixing an aqueous solution containing lithium (Li) element and an element A with the dispersion liquid, the element A comprising at least one selected from the group consisting of titanium (Ti), zirconium (Zr), tantalum (Ta), niobium (Nb), and aluminum (Al).

5 . The method for producing an active material according to claim 4 ,

wherein the preparing step is a step in which the liquid containing water and aggregates constituting the core portion are mixed, and a resulting mixture is disintegrated, to thereby obtain the dispersion liquid in which the powder constituting the core portion is dispersed.

6 . An electrode material mixture comprising the active material according to claim 1 and a solid electrolyte.

7 . A battery comprising:

a positive electrode layer;

a negative electrode layer; and

a solid electrolyte layer located between the positive electrode layer and the negative electrode layer,

wherein the positive electrode layer contains the active material according to claim 1 .