US-12626917-B2 - Positive electrode active material for nonaqueous electrolyte secondary batteries, and nonaqueous electrolyte secondary battery

US12626917B2US 12626917 B2US12626917 B2US 12626917B2US-12626917-B2

Abstract

A positive electrode active material for nonaqueous electrolyte secondary batteries according to one embodiment of the present disclosure contains a lithium transition metal composite oxide which is represented by general formula Li a Ni b Co c Al d X e O f (wherein 0.9≤a≤1.2; 0.88≤b≤0.96; 0≤c≤0.12; 0≤d≤0.12; 0≤e≤0.1; 1.9≤f≤2.1; (b+c+d)=1; and X represents at least one element that is selected from among Mn, Mg, Ca, Sr, Ba, Ti, Zr, V, Nb, Ta, Mo, W and B); and the lithium transition metal composite oxide has a pore volume of pores having a pore diameter of 0.3 μm or less of from 6×10 −4 mL/g to 50×10 −4 mL/g, while having a particle fracture strength of 120 MPa or more at the volume average particle diameter.

Inventors

Masanori Maekawa
Takayuki Ishikawa
Kaoru Nagata

Assignees

SANYO ELECTRIC CO., LTD.

Dates

Publication Date: 20260512
Application Date: 20210826
Priority Date: 20200904

Claims (7)

1 . A positive electrode active material for a non-aqueous electrolyte secondary battery, including a lithium-transition metal composite oxide represented by the general formula Li a Ni b Co c Al d X e O f , wherein 0.9≤a≤1.2, 0.88≤b≤0.96, 0≤c≤0.12, 0≤d≤0.12, 0≤e≤0.1, 1.9≤f≤2.1, b+c+d=1, and X represents at least one element selected from the group consisting of Mn, Mg, Ca, Sr, Ba, Ti, Zr, V, Nb, Ta, Mo, W, and B, wherein the lithium-transition metal composite oxide includes secondary particles formed by aggregation of primary particles, and has a volume of pores having a pore diameter of less than or equal to 0.3 μm, of greater than or equal to 6×10 −4 and less than or equal to 50×10 −4 mL/g, and a particle rupture strength at an average volume particle diameter, of greater than or equal to 120 MPa.
2 . The positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 1 , wherein the X adheres onto surfaces of the secondary particles or surfaces of the primary particles.
3 . A non-aqueous electrolyte secondary battery, comprising: a positive electrode including the positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 1 ; a negative electrode; and a non-aqueous electrolyte.
4 . The non-aqueous electrolyte secondary battery according to claim 3 , wherein the positive electrode has a positive electrode core and a positive electrode mixture layer formed on a surface of the positive electrode core, and a void ratio of the positive electrode mixture layer is less than or equal to 25 vol %.
5 . The non-aqueous electrolyte secondary battery according to claim 4 , wherein the void ratio of the positive electrode mixture layer is less than or equal to 22 vol %.
6 . The positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 1 , wherein a particle diameter of the primary particles constituting the secondary particles is greater than or equal to 0.05 μm and less than or equal to 1 μm.
7 . The positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 1 , wherein X represents at least one element selected from the group consisting of Ca, Ti, Nb, W, and B, and X adheres onto surfaces of the secondary particles.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application is a National Phase Application filed under 35 U.S.C. § 371 of International Application No. PCT/JP2021/031277 filed on Aug. 26, 2021 which claims the benefit of priority under 35 U.S.C. $119(a) of Japanese Patent Application No. 2020-149324 filed in Japan on Sep. 4, 2020, the contents of which are incorporated herein by reference. TECHNICAL FIELD The present disclosure relates to a positive electrode active material for a non-aqueous electrolyte secondary battery, and a non-aqueous electrolyte secondary battery. BACKGROUND ART For batteries with high capacity, a lithium nickelate-based positive electrode active material is widely used. Patent Literature 1 discloses art in which a lithium nickelate-based positive electrode active material having an average crushing strength (particle rupture strength) of greater than or equal to 15 and less than or equal to 100 MPa is used to regulate a contact area between an electrolyte liquid and the positive electrode active material within a certain range, thereby improving cycle characteristics and output characteristics of the battery. CITATION LIST Patent Literature PATENT LITERATURE 1: Japanese Unexamined Patent Application Publication No. 2007-257985 SUMMARY Technical Problem In recent years, a Ni content in the lithium nickelate has been increased from the viewpoint of higher capacity. The present inventors' investigation has found that, in the lithium-nickelate system with high Ni content, even a positive electrode active material having the physical properties disclosed in Patent Literature 1 may deteriorate the battery capacity and the cycle characteristics. Patent Literature 1 still has a room for improvement in terms of achievement of both of the battery capacity and the cycle characteristics of the battery. It is an advantage of the present disclosure to provide a positive electrode active material for a non-aqueous electrolyte secondary battery that contributes to achievement of both of the battery capacity and the cycle characteristics. Solution to Problem A positive electrode active material for a non-aqueous electrolyte secondary battery of an aspect of the present disclosure includes a lithium-transition metal composite oxide represented by the general formula LiaNibCocAldXeOf, wherein 0.9≤a≤1.2, 0.88≤b≤0.96, 0≤c≤0.12, 0≤d≤0.12, 0≤e≤0.1, 1.9≤f≤2.1, b+c+d=1, and X represents at least one element selected from the group consisting of Mn, Mg, Ca, Sr, Ba, Ti, Zr, V, Nb, Ta, Mo, W, and B, wherein the lithium-transition metal composite oxide has a volume of pores having a pore diameter of less than or equal to 0.3 μm, of greater than or equal to 6×10−4 and less than or equal to 50×10−4 mL/g, and a particle rupture strength at an average volume particle diameter, of greater than or equal to 120 MPa. A non-aqueous electrolyte secondary battery of an aspect of the present disclosure comprises: a positive electrode including the above positive electrode active material for a non-aqueous electrolyte secondary battery; a negative electrode; and a non-aqueous electrolyte. Advantageous Effect of Invention According to an aspect of the present disclosure, a secondary battery that achieves both of the battery capacity and the cycle characteristics may be obtained. BRIEF DESCRIPTION OF DRAWING FIG. 1 is a vertical sectional view of a cylindrical secondary battery of an example of an embodiment. DESCRIPTION OF EMBODIMENTS Hereinafter, an example of an embodiment of a non-aqueous electrolyte secondary batter according to the present disclosure will be described in detail. Hereinafter, a cylindrical battery housing a wound electrode assembly in a cylindrical exterior will be exemplified, but the electrode assembly is not limited to the wound electrode assembly, and may be a stacked electrode assembly in which a plurality of positive electrodes and a plurality of negative electrodes are alternately stacked one by one with a separator interposed therebetween. The shape of the exterior is not limited to the cylindrical shape, and may be, for example, a rectangular shape, a coin shape, or the like, and the exterior may be a pouch composed of laminated sheets including a metal layer and a resin layer. FIG. 1 is a vertical sectional view of a cylindrical secondary battery 10 of an example of an embodiment. In the secondary battery 10 illustrated in FIG. 1, an electrode assembly 14 and a non-aqueous electrolyte (not illustrated) are housed in an exterior 15. The electrode assembly 14 has a wound structure in which a positive electrode 11 and a negative electrode 12 are wound with a separator 13 interposed therebetween. Hereinafter, for convenience of description, a sealing assembly 16 side will be described as the “upper side”, and the bottom side of the exterior 15 will be described as the “lower side”. An opening end of the exterior 15 is capped with the sealing assembly 16 to seal inside the secondary battery 10. Insulat