An electrochemical apparatus includes an electrode assembly. The electrode assembly includes a first electrode plate, a first separation layer, a second electrode plate, and a second separation layer. Along a first direction, the first separation layer includes a first protruding portion extending beyond the second electrode plate, and the second separation layer includes a second protruding portion extending beyond the second electrode plate. The first protruding portion includes a first bonding area, the second protruding portion includes a second bonding area, and adhesion between the first bonding area and the second bonding area is F1, where F1≥5 N/m. Separation layers on two sides of an electrode plate are bonded to prevent the separation layers from shrinking at high temperatures or prevent the separation layers from turning inward at edges due to impact from an electrolyte when the electrochemical apparatus falls, thereby preventing a short circuit.

An electrochemical apparatus includes an electrode assembly. The electrode assembly includes a first electrode plate, a first separation layer, a second electrode plate, and a second separation layer. Along a first direction, the first separation layer includes a first protruding portion extending beyond the second electrode plate, and the second separation layer includes a second protruding portion extending beyond the second electrode plate. The first protruding portion includes a first bonding area, the second protruding portion includes a second bonding area, and adhesion between the first bonding area and the second bonding area is F1, where F1≥5 N/m. Separation layers on two sides of an electrode plate are bonded to prevent the separation layers from shrinking at high temperatures or prevent the separation layers from turning inward at edges due to impact from an electrolyte when the electrochemical apparatus falls, thereby preventing a short circuit.

A battery includes a negative electrode active material layer, a positive electrode active material layer. The negative electrode active material layer includes a first portion and a second portion including a first surface and a first end. The first surface is connected to the first portion by using a first connection part. A thickness of the second portion decreases from the first connection part to the first end. The positive electrode active material layer includes a third portion and a fourth portion including a second surface and a second end. The first surface is at least partially opposite to the second surface, and the second surface is connected to the third portion by using a second connection part. A thickness of the fourth portion gradually decreases from the second connection part to the second end. The first connection part is located between the second connection part and the second end.

A battery includes a negative electrode active material layer, a positive electrode active material layer. The negative electrode active material layer includes a first portion and a second portion including a first surface and a first end. The first surface is connected to the first portion by using a first connection part. A thickness of the second portion decreases from the first connection part to the first end. The positive electrode active material layer includes a third portion and a fourth portion including a second surface and a second end. The first surface is at least partially opposite to the second surface, and the second surface is connected to the third portion by using a second connection part. A thickness of the fourth portion gradually decreases from the second connection part to the second end. The first connection part is located between the second connection part and the second end.

An embodiment of the present invention relates to a cylindrical secondary battery comprising: a cylindrical can having one open end; an electrode assembly received in the can, and wherein a first electrode plate having a first electrode uncoated part, a separator, a second electrode plate having a second electrode uncoated part disposed in a direction opposite to the first electrode uncoated part are stacked and wound into a cylindrical shape; and a cap assembly for closing the open end of the can while the electrode assembly is received in the can, wherein an end of at least one of the first electrode uncoated part and the second electrode uncoated part is bent to form a bending part. An embodiment of the present invention is advantageous for a welding process in that, when a current collection plate is welded, the thickness and number of weldable substrates are increased and the gaps between the substrates are reduced, thereby increasing the heat capacity of a welding part. Furthermore, there are fewer empty spaces between the substrates after the substrates are compacted for welding than a structure having no bending part, and thus the electrode plates or the separator can be prevented from being damaged due to the penetration of welding heat, thereby improving a stability risk.

An embodiment of the present invention relates to a cylindrical secondary battery comprising: a cylindrical can having one open end; an electrode assembly received in the can, and wherein a first electrode plate having a first electrode uncoated part, a separator, a second electrode plate having a second electrode uncoated part disposed in a direction opposite to the first electrode uncoated part are stacked and wound into a cylindrical shape; and a cap assembly for closing the open end of the can while the electrode assembly is received in the can, wherein an end of at least one of the first electrode uncoated part and the second electrode uncoated part is bent to form a bending part. An embodiment of the present invention is advantageous for a welding process in that, when a current collection plate is welded, the thickness and number of weldable substrates are increased and the gaps between the substrates are reduced, thereby increasing the heat capacity of a welding part. Furthermore, there are fewer empty spaces between the substrates after the substrates are compacted for welding than a structure having no bending part, and thus the electrode plates or the separator can be prevented from being damaged due to the penetration of welding heat, thereby improving a stability risk.

An electrode assembly, a battery cell, a battery, and a method and device for manufacturing an electrode assembly are provided. In some embodiments, the electrode assembly includes a positive electrode plate and a negative electrode plate. The positive electrode plate and the negative electrode plate are wound or folded to form a bend region. The positive electrode plate includes a plurality of bend portions located in the bend region. Each bend portion includes a positive current collecting layer and a positive active material layer. The positive current collecting layer is coated with the positive active material layer on at least one surface in a thickness direction of the positive electrode plate. A barrier layer is disposed between the positive current collecting layer and the positive active material layer.

An electrode assembly, a battery cell, a battery, and a method and device for manufacturing an electrode assembly are provided. In some embodiments, the electrode assembly includes a positive electrode plate and a negative electrode plate. The positive electrode plate and the negative electrode plate are wound or folded to form a bend region. The positive electrode plate includes a plurality of bend portions located in the bend region. Each bend portion includes a positive current collecting layer and a positive active material layer. The positive current collecting layer is coated with the positive active material layer on at least one surface in a thickness direction of the positive electrode plate. A barrier layer is disposed between the positive current collecting layer and the positive active material layer.

An embodiment of the present invention relates to a cylindrical secondary battery comprising: a cylindrical can having a bottom surface and a side portion extending from the bottom surface, one end of the side portion being open to form an opening; an electrode assembly accommodated in the can; and a cap assembly including a gasket which is inserted into the can with the electrode assembly inserted in the can to come into contact with the electrode assembly, and a cap plate which is disposed on the gasket and is electrically connected to the electrode assembly, wherein the can has, at the edge of the opening, a curling portion which presses the gasket to bring the gasket into contact with the cap plate.

An embodiment of the present invention relates to a cylindrical secondary battery comprising: a cylindrical can having a bottom surface and a side portion extending from the bottom surface, one end of the side portion being open to form an opening; an electrode assembly accommodated in the can; and a cap assembly including a gasket which is inserted into the can with the electrode assembly inserted in the can to come into contact with the electrode assembly, and a cap plate which is disposed on the gasket and is electrically connected to the electrode assembly, wherein the can has, at the edge of the opening, a curling portion which presses the gasket to bring the gasket into contact with the cap plate.