EP-4738494-A1 - ELECTRODE ASSEMBLY AND BATTERY CELL

EP4738494A1EP 4738494 A1EP4738494 A1EP 4738494A1EP-4738494-A1

Abstract

This application discloses an electrode assembly and a battery cell. The electrode assembly includes a first electrode plate unit and a second electrode plate unit that are wound together. A polarity of the first electrode plate unit is opposite to that of the second electrode plate unit. At least one of the first electrode plate unit or the second electrode plate unit includes an electrode plate, a tab, and a separator. The separator includes a first separator film and a second separator film arranged on two opposite sides of the electrode plate respectively in a thickness direction of the electrode plate. The first separator film includes a first extension portion extending beyond an edge of the electrode plate along a width direction of the electrode plate. The second separator film includes a second extension portion extending beyond the edge of the electrode plate along the width direction of the electrode plate. The tab is disposed on the electrode plate. The tab extends out of the separator from between the first extension portion and the second extension portion. A part of the first extension portion is connected to a part of the second extension portion to form sealing regions. There are at least two sealing regions. The sealing regions avoid the tab. The electrode assembly provided herein can effectively improve anti-drop performance of the battery cell.

Inventors

HUANG, ZEYU
GUO, Peipei
LI, HU
WANG, HUILING

Assignees

Ningde Amperex Technology Limited

Dates

Publication Date: 20260506
Application Date: 20240607

Claims (12)

An electrode assembly, characterized in that the electrode assembly comprises a first electrode plate unit and a second electrode plate unit that are wound together; and a polarity of the first electrode plate unit is opposite to that of the second electrode plate unit; at least one of the first electrode plate unit or the second electrode plate unit comprises an electrode plate, a tab, and a separator; the separator comprises a first separator film and a second separator film arranged on two opposite sides of the electrode plate in a thickness direction of the electrode plate respectively; the first separator film comprises a first extension portion extending beyond an edge of the electrode plate along a width direction of the electrode plate; the second separator film comprises a second extension portion extending beyond the edge of the electrode plate along the width direction of the electrode plate; the tab is disposed on the electrode plate; the tab extends out of the separator from between the first extension portion and the second extension portion; the first extension portion is connected to the second extension portion to form sealing regions; there are at least two sealing regions; and the sealing regions avoid the tab.
The electrode assembly according to claim 1, characterized in that at least a part of the sealing regions are spaced apart along a length direction of the electrode plate; in the length direction of the electrode plate, a length of the electrode plate is L, a length of each sealing region is l 0 , and a distance between two adjacent sealing regions is a1, satisfying: 1 < L / l 0 ≤ 200 ; and/or 200 ≤ L / a 1 ≤ 4000 ; and/or 1 ≤ l 0 / a 1 ≤ 4000 .
The electrode assembly according to claim 2, characterized in that a part of the sealing regions are spaced apart along the length direction of the electrode plate, and another part of the sealing regions are spaced apart along a width direction of the electrode plate; in the width direction of the electrode plate, a width of the electrode plate is W, a width of each sealing region is w 0 , and a width between two adjacent sealing regions is a2, satisfying: 1 ≤ W / w 0 ≤ 20 ; and/or W / a 2 ≥ 20 ; and/or w 0 / a 2 ≥ 1 .
The electrode assembly according to claim 1, characterized in that in the width direction of the electrode plate, the first extension portion comprises a first part located on one side of the electrode plate, and a part of the first part is connected to the second extension portion to form at least two sealing regions; in the width direction of the electrode plate, one end of the first separator film facing away from the first part is integrally formed with the second separator film; or in the width direction of the electrode plate, the first extension portion comprises a second part facing away from the first part, and a part of the second part is connected to the second extension portion to form at least one sealing region.
The electrode assembly according to claim 1, characterized in that each of the sealing regions is a hot-pressed sealing portion or a calendered sealing portion; or an adhesive layer is disposed between the first extension portion and the second extension portion, and the first extension portion and the second extension portion are connected by the adhesive layer to form the sealing region.
The electrode assembly according to claim 1, characterized in that the electrode assembly comprises a straight part and a curved part, and the sealing region is disposed on the straight part.
The electrode assembly according to claim 6, characterized in that the sealing regions are correspondingly arranged in a thickness direction of the electrode assembly, and the first extension portion and the second extension portion of the curved portion are spaced apart.
The electrode assembly according to claim 1, characterized in that the electrode assembly comprises two electrode plates, at least two tabs, and one separator; at least one tab is disposed on one of the electrode plates, and the electrode plate is disposed between the first separator film and the second separator film of the separator to form the first electrode plate unit; a remaining tab is disposed on the other electrode plate to form the second electrode plate unit; and the two electrode plates are opposite in polarity; or the electrode assembly comprises two electrode plates, at least two tabs, and two separators; at least one tab is disposed on one of the electrode plates, and the electrode plate is disposed between the first separator film and the second separator film of one of the separators to form the first electrode plate unit; a remaining tab is disposed on the other electrode plate and the electrode plate is disposed between the first separator film and the second separator film of the other separator to form the second electrode plate unit; and the two electrode plates are opposite in polarity.
The electrode assembly according to claim 8, characterized in that the tab extends out of the separator along the width direction of the electrode plate; and, in the width direction of the electrode plate, a width of one of the electrode plates is less than a width of the other electrode plate, and at least the electrode plate with a smaller width is disposed between the first separator film and the second separator film of the separator.
The electrode assembly according to claim 9, characterized in that the electrode plate with a smaller width is a positive electrode plate, and the electrode plate with a larger width is a negative electrode plate.
The electrode assembly according to claim 1, characterized in that the sealing regions are spaced apart from the electrode plate, a distance from a sealing region edge facing the electrode plate to an edge of the electrode plate is S, and S satisfies: 0.1 mm ≤ S ≤ 1 mm; and/or the tab extends out of the separator along the width direction of the electrode plate; in a length direction of the electrode plate, one of the sealing regions is disposed on one side of the tab, and the other sealing region is disposed on the other side of the tab, and a distance from a sealing region edge to an edge of the tab is Q, and Q satisfies: 0.2 mm ≤ Q ≤ 2 mm.
A battery cell, characterized in that the battery cell comprises: a packaging bag; and the electrode assembly according to any one of claims 1 to 11, wherein the electrode assembly is disposed in the packaging bag.

Description

This application claims priority to Chinese Patent Application No. 202310802063.8, filed with China National Intellectual Property Administration on June 30, 2023 and entitled "ELECTRODE ASSEMBLY AND BATTERY CELL", which is incorporated herein by reference in its entirety. TECHNICAL FIELD This application relates to the field of electrochemical technology, and in particular, to an electrode assembly and a battery cell. BACKGROUND As the Computer, Communication, Consumer Electronics (3C) electronic products are used in more diverse and more complex scenarios, safety requirements imposed by people on the electronic products are increasingly stringent, and attention to battery safety is growing. After a battery is dropped repeatedly, the battery is prone to voltage drop or even fire and explosion. Through research, it is found that a main cause of voltage drop or fire and explosion of a dropped battery is an internal short circuit caused by shrinkage of a separator inside the battery. During repeated drops, free electrolyte solution repeatedly impacts the separator. When an impact force of the electrolyte solution exceeds a binding force of the separator, the separator inside the battery shrinks, and a positive electrode plate directly contacts a negative electrode plate, resulting in an internal short circuit. Consequently, voltage drops significantly, and the battery fails or even directly smokes and catches fire. Therefore, the shrinkage of the separator poses a severe threat to battery safety and urgently needs to be addressed. SUMMARY Some embodiments of this application provide an electrode assembly and a battery cell to solve the problem that the anti-drop performance of the battery cell is poor. According to a first aspect, this application provides an electrode assembly. The electrode assembly includes a first electrode plate unit and a second electrode plate unit that are wound together. A polarity of the first electrode plate unit is opposite to that of the second electrode plate unit. At least one of the first electrode plate unit or the second electrode plate unit includes an electrode plate, a tab, and a separator. The separator includes a first separator film and a second separator film arranged on two opposite sides of the electrode plate respectively in a thickness direction of the electrode plate. The first separator film includes a first extension portion extending beyond an edge of the electrode plate along a width direction of the electrode plate. The second separator film includes a second extension portion extending beyond the edge of the electrode plate along the width direction of the electrode plate. The tab is disposed on the electrode plate. The tab extends out of the separator from between the first extension portion and the second extension portion. The first extension portion is connected to the second extension portion to form sealing regions. There are at least two sealing regions. The sealing regions avoid the tab. In the electrode assembly in an embodiment of this application, the part of the first separator film extending beyond the width of the electrode plate is connected to the part of the second separator film extending beyond the width of the electrode plate in a specified manner, and the connection is solidified to form a sealing region, thereby preventing occurrence of a voltage drop or a short circuit of the battery cell caused by contact between the positive electrode plate and the negative electrode plate. Two adjacent sealing regions are spaced apart, and an electrolyte solution can enter a space between the first separator film and the second separator film from a region at which the first separator film is not connected to the second separator film, so that the electrolyte solution still infiltrates the electrode assembly sufficiently. The sealing regions avoid the tab, thereby preventing excessive pressure on the tab and the electrode plate correspondingly connected to the tab, and effectively improving the stability of the performance of the resulting battery cell. In some exemplary embodiments, at least a part of the sealing regions are spaced apart along a length direction of the electrode plate. In the length direction of the electrode plate, a length of the electrode plate is L, a length of each sealing region is l0, and a width between two adjacent sealing regions is a1, satisfying: 1<L/l0≤200; and/or 200≤L/a1≤4000; and/or 1≤l0/a1≤4000. Based on the above embodiment, by controlling the ratios of L and l0 to a1 to fall within appropriate ranges, it is convenient to distribute the length and spacing of the sealing regions in the length direction of the electrode plate, so that the sealing regions are firmly encapsulated in the length direction of the electrode plate and are efficiently infiltrated by the electrolyte solution. In some exemplary embodiments, a part of the sealing regions are spaced apart along the length direction of the electrode plate, and