An electrode sheet includes a current collector and a first active material layer on a first surface of the current collector. The first active material layer includes a main portion and a first buffer portion. The main portion includes a first inner surface and an outer surface. The first inner surface is attached to the current collector, and the outer surface is parallel to the first inner surface. The first active material layer has a height that is a vertical distance from the outer surface to the first inner surface. The first buffer portion includes a second inner surface, a buffer surface, and an inner wall surface defining a first groove. A first end of the buffer surface is connected to the outer surface, a second end of the buffer surface is connected to the inner wall surface. The inner wall surface is shorter than the first active material layer.

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.

The present invention relates to a battery cell with improved safety and a method of manufacturing the same, and more particularly a battery cell configured such that an electrode assembly including a positive electrode (200) and a negative electrode (300) located so as to be opposite each other in the state in which a separator (400) is interposed therebetween is received in a cell case (100), wherein the positive electrode (200) includes a positive electrode plate (210) and a positive electrode active material layer (220) provided on one surface and/or the other surface of the positive electrode plate (210), the negative electrode (300) includes a negative electrode plate (310) and a negative electrode active material layer (320) provided on one surface and/or the other surface of the negative electrode plate (310), the positive electrode active material layer (220) includes a first flat portion (221) and a first inclined portion (222) provided at each of opposite sides of the first flat portion (221), and the negative electrode active material layer (320) includes a second flat portion (321) and a second inclined portion (322) provided at each of opposite sides of the second flat portion (321) and a method of manufacturing the same.

An electrode includes an active material coating portion coated with an electrode active material on at least one surface of an electrode collector; and an active material non-coating portion which is at one side of the active material coating portion, is not coated with the electrode active material, and includes at least one slit extending from one end to the another end thereof, wherein in each slit of the at least one slit, a hole is passes through a point at which the respective slit and the active material coating portion meet each other.

An electrode includes an active material coating portion coated with an electrode active material on at least one surface of an electrode collector; and an active material non-coating portion which is at one side of the active material coating portion, is not coated with the electrode active material, and includes at least one slit extending from one end to the another end thereof, wherein in each slit of the at least one slit, a hole is passes through a point at which the respective slit and the active material coating portion meet each other.

In a metal negative electrode, a current collector includes a through-hole or a recess provided to extend from a front surface of a planar plate toward a back surface of the planar plate. A distance from a midpoint of a joining boundary to a point on a surface of the current collector is designated as a region dividing distance, the point defining a distance less than a maximum distance between the midpoint and a side or a surface of the current collector. In the current collector, a first region is a region defined by distances from the midpoint, the distances being a distance equal to the region dividing distance and distances greater than the region dividing distance, and, in the current collector, a second region is a region defined by distances from the midpoint that are less than the region dividing distance. A volume reduction ratio of the first region is greater than a volume reduction ratio of the second region, the volume reduction ratio of the first region being a ratio with respect to a volume of the first region determined assuming that the through-hole or the recess is not present, the volume reduction ratio of the second region being a ratio with respect to a volume of the second region determined assuming that the through-hole or the recess is not present.

In a secondary battery including a large-sized electrode group including stacked positive and negative electrode plates, an electrode plate in which failures such as the separation and cracking of an active material layer and the abrasion and cracking of a current collector are unlikely to occur is provided. An electrode plate 21 includes a coated region CR where active material layers 21a are formed and an uncoated region NC where no active material layer is formed and has a configuration in which a boundary section between the coated region and the uncoated region is provided with a first buffer region C2 having a non-linear irregular shape in plan view.

In a secondary battery including a large-sized electrode group including stacked positive and negative electrode plates, an electrode plate in which failures such as the separation and cracking of an active material layer and the abrasion and cracking of a current collector are unlikely to occur is provided. An electrode plate 21 includes a coated region CR where active material layers 21a are formed and an uncoated region NC where no active material layer is formed and has a configuration in which a boundary section between the coated region and the uncoated region is provided with a first buffer region C2 having a non-linear irregular shape in plan view.

A positive electrode (100) includes a positive electrode current collector (110), a positive electrode mixture (120), and a mixture (130). The positive electrode current collector (110) has a first surface (112). The first surface (112) of the positive electrode current collector (110) includes a first region (112a), a second region (112b), and a third region (112c). The positive electrode (100) satisfies the following expression (1).

0≤L3/(L1+L3)≤0.075  (1)

Here, L1 is a length of the positive electrode (100) of the first region (112a) of the positive electrode (100) in one direction (first direction (X)), and L3 is a length of the third region (112c) of the positive electrode (100) in the one direction (first direction (X)).