US-20260128386-A1 - ELECTRODE ASSEMBLY, CYLINDRICAL BATTERY CELL, AND BATTERY PACK AND VEHICLE INCLUDING THE SAME

US20260128386A1US 20260128386 A1US20260128386 A1US 20260128386A1US-20260128386-A1

Abstract

An electrode assembly having a first electrode, a second electrode, and a separator positioned between the first electrode and the second electrode. The first electrode, the second electrode, and the separator are together wound about an axis in a winding direction resulting in a plurality of winding turns. Each of the first electrode and the second electrode has a first side and a second side opposite the first side in the direction of the axis, as well as a first, electrode active material portion, coated with an electrode active material, extending from the second side in the direction of the first side, and a second, uncoated portion extending from the first side in the direction of the second side to the active material of the first portion. Additionally, the first side of the first electrode and the first side of the second electrode are divided into a plurality of segments by a cut groove, and each of the segments has a first end corresponding to the first side of either the first or the second electrode. One or more of the segments are bent in a radial direction relative to the axis, at a point below the first end of each bent segment, and the separator has a side that is positioned between the bending point of each bent segment and a boundary between the first and the second portions.

Inventors

Myung-An LEE
Duk-Hyun RYU
Jae-young Woo

Assignees

LG ENERGY SOLUTION, LTD.

Dates

Publication Date: 20260507
Application Date: 20251226
Priority Date: 20211015

Claims (20)

1 . An electrode assembly comprising: a first electrode, a second electrode, and a separator between the first electrode and the second electrode, wherein the first electrode, the second electrode, and the separator are together wound about an axis in one winding direction to have a plurality of winding turns, wherein each of the first electrode and the second electrode comprises a first side and a second side opposite the first side in a direction of the axis, wherein each of the first electrode and the second electrode further comprises a first, electrode active material portion, coated with an electrode active material, extending from the second side in the direction of the first side, and a second uncoated portion extending from the first side in the direction of the second side to the active material of the first portion, wherein the first side of the first and the second electrodes is divided into a plurality of segments by a cut groove having a predetermined length, wherein each of the segments has a first end corresponding to the first side of the first and second electrodes, wherein one or more of the segments are bent in a radial direction relative to the axis, at a point below the first end in each segment, wherein the side of the separator is positioned between the bending point and a base line, or positioned below the base line in the axis direction, and wherein the base line is represented by a straight line extending in a winding direction (X) at a height corresponding to a notching valley of cut grooves dividing the plurality of segments, wherein a bent segment is a segment that is bent among the segments and a shortest bent segment is a segment that has a shortest length among the plurality of bent segments, the side of the separator is located below the base line and at a distance from the base line that is no greater than 30% of the total length of the shortest bent segment, and wherein the total length of the shortest bent segment is the length from the base line corresponding to the shortest bent segment to the first end of the shortest bent segment.
2 . The electrode assembly of claim 1 , wherein the separator has a side that is positioned between the bending point of each bent segment and a boundary between the first and the second portions.
3 . The electrode assembly of claim 1 , wherein a base line is represented by a straight line extending in the winding direction and corresponding to a notching valley of each cut grooves.
4 . The electrode assembly of claim 3 , wherein a length from the first end of each segment to the base line is variable.
5 . The electrode assembly according to claim 1 , wherein the second, uncoated portion includes a core-side uncoated portion adjacent to a core of the electrode assembly, a circumferential uncoated portion adjacent to an outer circumferential surface of the electrode assembly, and an intermediate uncoated portion interposed between the core-side uncoated portion and the circumferential uncoated portion, and at least one of the core-side uncoated portion and the circumferential uncoated portion has a relatively shorter length from the base line to the first side than the intermediate uncoated portion.
6 . The electrode assembly according to claim 5 , wherein the core-side uncoated portion has a relatively shorter length from the base line to the first side than the intermediate uncoated portion and the circumferential uncoated portion.
7 . The electrode assembly according to claim 5 , wherein the first side of the core-side uncoated portion and the base line coincide with each other.
8 . The electrode assembly according to claim 5 , wherein the core-side uncoated portion includes an uncoated portion corresponding to an innermost winding turn of the electrode assembly, and the circumferential uncoated portion includes an uncoated portion corresponding to an outermost winding turn of the electrode assembly.
9 . The electrode assembly according to claim 5 , wherein all or at least a partial region of the intermediate uncoated portion is divided into a plurality of segments.
10 . The electrode assembly according to claim 1 , wherein a distance between the bending point and the side of the separator is greater than or equal to 0.1 mm.
11 . The electrode assembly according to claim 1 , wherein the length from bending point to base line of the shortest bent segment is greater than or equal to 2 mm.
12 . The electrode assembly according to claim 1 further comprising: at least one segment (segment A) having a height less than the shortest bent segment, otherwise the shortest bent segment is the segment having a minimum height, wherein segment height means a shortest length from the base line to the first end.
13 . The electrode assembly according to claim 5 , wherein at least a partial region of the intermediate uncoated portion is configured to have a height in the winding axis direction, which increases stepwise from the core to the outer circumference.
14 . The electrode assembly according to claim 1 , wherein at least one of segment height and segment width increases stepwise in the winding direction from the core to the outer circumference individually or in groups.
15 . The electrode assembly according to claim 1 , wherein each of the plurality of segments satisfies at least one of the following conditions: a width of 1 mm to 6 mm in the winding direction; a height of 2 mm to 10 mm in the axis direction; and a separation pitch of 0.05 mm to 1 mm in the winding direction.
16 . The electrode assembly according to claim 1 , wherein the plurality of segments satisfy a separation pitch condition of 0.05 mm to 1 mm in the winding direction, the separation pitch is defined as a distance between corners of two segments adjacent to each other, and wherein round reinforcing portions are formed to the corners of the segments adjacent to each other.
17 . The electrode assembly according to claim 1 , wherein the separator comprises a porous polymer substrate; and a porous coating layer located on at least one surface of the porous polymer substrate, wherein the porous coating layer comprises a plurality of inorganic particles and binder polymer.
18 . The electrode assembly according to claim 17 , wherein the inorganic particles comprise inorganic particles having a hydrophilic property.
19 . A cylindrical battery cell, comprising an electrode assembly according to claim 1 , and further comprising: a battery can configured to accommodate the electrode assembly and electrically connected to one of the first electrode and the second electrode to have a first polarity; a sealing body configured to seal an open end of the battery can; and a terminal electrically connected to the other of the first electrode and the second electrode to have a second polarity and configured to have a surface exposed to the outside, wherein the separator comprises a porous polymer substrate; and a porous coating layer located on both surfaces of the porous polymer substrate and comprising inorganic particles and a binder polymer.
20 . A battery pack, comprising at least one battery cell according to claim 19 .

Description

CROSS-REFERENCE WITH RELATED APPLICATION(S) This application is a Continuation of Ser. No. 17/967,614 filed Oct. 17, 2022, now allowed, which claims the benefit of and priority of Korean Patent Application No. 10-2021-0175085 filed on Dec. 8, 2021, Korean Patent Application No. 10-2021-0137939 filed Oct. 15, 2021 and Korean Patent Application No. 10-2022-0089239 filed Jul. 19, 2022, the disclosures of which are incorporated herein by reference in their entirety. TECHNICAL FIELD The present application claims priority to Korean Patent Application No. 10-2021-0137939 filed on Oct. 15, 2021, Korean Patent Application No. 10-2021-0175085 filed on Dec. 8, 2021 and Korean Patent Application No. 10-2022-0089239 filed on Jul. 19, 2022 in the Republic of Korea. The present disclosure relates to an electrode assembly, a cylindrical battery cell, and a battery pack and a vehicle including the same. BACKGROUND ART Secondary batteries that are easily applicable to various product groups and have electrical characteristics such as high energy density are universally applied not only to portable devices but also to electric vehicles (EVs) or hybrid electric vehicles (HEVs) driven by an electric drive source. These secondary batteries are attracting attention as a new energy source to improve eco-friendliness and energy efficiency because they have the primary advantage that they can dramatically reduce the use of fossil fuels as well as the secondary advantage that no by-products are generated from the use of energy. Secondary batteries currently widely used in the art include lithium ion batteries, lithium polymer batteries, nickel cadmium batteries, nickel hydrogen batteries, nickel zinc batteries, and the like. A unit secondary battery cell, namely a unit battery cell, has an operating voltage of about 2.5V to 4.5V. Therefore, when a higher output voltage is required, a battery pack may be configured by connecting a plurality of battery cells in series. In addition, a plurality of battery cells may be connected in parallel to form a battery pack according to the charge/discharge capacity required for the battery pack. Accordingly, the number of battery cells included in the battery pack and the form of electrical connection may be variously set according to the required output voltage and/or charge/discharge capacity. Meanwhile, as a kind of unit secondary battery cell, there are known cylindrical, rectangular, and pouch-type battery cells. In the case of a cylindrical battery cell, a separator serving as an insulator is interposed between a positive electrode and a negative electrode, and they are wound to form an electrode assembly in the form of a jelly roll, which is inserted into a battery can to configure a battery. In addition, a strip-shaped electrode tab may be connected to an uncoated portion of each of the positive electrode and the negative electrode, and the electrode tab electrically connects the electrode assembly and an electrode terminal exposed to the outside. For reference, the positive electrode terminal is a cap plate of a sealing body that seals the opening of the battery can, and the negative electrode terminal is the battery can. However, according to the conventional cylindrical battery cell having such a structure, since current is concentrated in the strip-shaped electrode tab coupled to the uncoated portion of the positive electrode and/or the uncoated portion of the negative electrode, the current collection efficiency is not good due to large resistance and large heat generation. For small cylindrical battery cells with a form factor of 18650 or 21700, resistance and heat are not a major issue. However, when the form factor is increased to apply the cylindrical battery cell to an electric vehicle, the cylindrical battery cell may ignite while a lot of heat is generated around the electrode tab during the rapid charging process. In order to solve this problem, there is provided a cylindrical battery cell (so-called tab-less cylindrical battery cell) in which the uncoated portion of the positive electrode and the uncoated portion of the negative electrode are designed to be positioned at the top and bottom of the jelly-roll type electrode assembly, respectively, and the current collecting plate is welded to the uncoated portion to improve the current collecting efficiency. FIGS. 1 to 3 are diagrams showing a process of manufacturing a tab-less cylindrical battery cell. FIG. 1 shows the structure of an electrode plate, FIG. 2 shows a process of winding the electrode plate, and FIG. 3 shows a process of welding a current collecting plate to a bent surface of an uncoated portion. Referring to FIGS. 1 to 3, a positive electrode plate 10 and a negative electrode plate 11 have a structure in which a sheet-shaped current collector 20 is coated with an active material 21, and include an uncoated portion 22 at one long side along the winding direction X. An electrode assembly A is manufactured by seq