A negative electrode active material having a specific aspect ratio and sphericity in a cumulative particle volume distribution. When tested by using a dynamic particle image analyzer, when a cumulative particle volume distribution of the negative electrode active material is 10%, an aspect ratio AR.sub.10 of the negative electrode active material satisfies 0.4≤AR.sub.10≤0.55, and a sphericity S.sub.10 of the negative electrode active material satisfies 0.48≤S.sub.10≤0.60. The negative electrode active material improves rate performance, dynamics performance, and a deformation problem of the electrochemical apparatus.

A negative electrode active material having a specific aspect ratio and sphericity in a cumulative particle volume distribution. When tested by using a dynamic particle image analyzer, when a cumulative particle volume distribution of the negative electrode active material is 10%, an aspect ratio AR.sub.10 of the negative electrode active material satisfies 0.4≤AR.sub.10≤0.55, and a sphericity S.sub.10 of the negative electrode active material satisfies 0.48≤S.sub.10≤0.60. The negative electrode active material improves rate performance, dynamics performance, and a deformation problem of the electrochemical apparatus.

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.

An electrode sheet includes a current collector and a first active material layer coated on a first surface of the current collector. The first active material layer includes a first groove, and the first groove includes a first side wall, a second side wall, and a third side wall. The first side wall and the second side wall are arranged parallel to each other, and the third side wall connects the first side wall and the second side wall. The first groove has a width that is a distance from the first side wall to the second side wall, and a length of a surface contour of a cross-section view of the third side wall is greater than the width of the first groove.

An electrode sheet includes a current collector and a first active material layer coated on a first surface of the current collector. The first active material layer includes a first groove, and the first groove includes a first side wall, a second side wall, and a third side wall. The first side wall and the second side wall are arranged parallel to each other, and the third side wall connects the first side wall and the second side wall. The first groove has a width that is a distance from the first side wall to the second side wall, and a length of a surface contour of a cross-section view of the third side wall is greater than the width of the first groove.

Disclosed are a cathode materials suitable for an aluminium ion battery, wherein the cathode materials comprise a main group element nitride, and an oxide of a main group element or an oxide of a element in Group 1 to 13. The nitride is preferably a 2-dimensional layered material. Preferably, the ratio of the main group element nitride to the oxide is between 5:95 and 95:5 (by weight).

Disclosed are a cathode materials suitable for an aluminium ion battery, wherein the cathode materials comprise a main group element nitride, and an oxide of a main group element or an oxide of a element in Group 1 to 13. The nitride is preferably a 2-dimensional layered material. Preferably, the ratio of the main group element nitride to the oxide is between 5:95 and 95:5 (by weight).

This positive electrode active substance for a non-aqueous electrolyte secondary battery contains a lithium-transition metal composite oxide which has a crystal structure belonging to the space group Fm-3m and is represented by the compositional formula Li.sub.xMn.sub.yM.sub.aO.sub.bF.sub.c (in the formula: M is at least one type of metal element excluding Mn; x+y+a=b+c=2; 1<x≤1.35; 0.4≤y≤0.9; 0≤a≤0.2; and 1.3≤b≤1.8). In addition, the lattice constant a of the lithium-transition metal composite oxide is 4.09-4.16.

This positive electrode active substance for a non-aqueous electrolyte secondary battery contains a lithium-transition metal composite oxide which has a crystal structure belonging to the space group Fm-3m and is represented by the compositional formula Li.sub.xMn.sub.yM.sub.aO.sub.bF.sub.c (in the formula: M is at least one type of metal element excluding Mn; x+y+a=b+c=2; 1<x≤1.35; 0.4≤y≤0.9; 0≤a≤0.2; and 1.3≤b≤1.8). In addition, the lattice constant a of the lithium-transition metal composite oxide is 4.09-4.16.

A pouch-type secondary battery includes an electrode assembly having a structure in which electrodes and separators are alternately disposed; and a pouch-type exterior configured to accommodate the electrode assembly, wherein the exterior includes an accommodation part defining a space accommodating the electrode assembly; and a sealing part disposed along a circumference of the accommodation part in which some areas of the exterior are attached to each other so that the accommodation part is sealed from an outside, wherein a plurality of corners are disposed on the sealing part, at least one corner of the plurality of corners includes a recess part recessed toward the electrode assembly; and a diagonal part disposed adjacent to the recess part and extending toward the recess part in a diagonal direction crossing a longitudinal direction of the exterior.