Search

CN-121983744-A - Battery cell and battery pack

CN121983744ACN 121983744 ACN121983744 ACN 121983744ACN-121983744-A

Abstract

The invention relates to the technical field of batteries, in particular to a battery cell and a battery pack. The battery cell comprises a shell, wherein the shell is provided with a first discharging area and a second discharging area, the first discharging area is provided with a groove for thinning the thickness of the first discharging area, the second discharging area is provided with an exhaust hole penetrating through the shell, a first notch is arranged in the first discharging area, the projection of the groove on a plane parallel to the first discharging area can cover the projection of the first notch on the plane parallel to the first discharging area, a pressure release piece is arranged in the exhaust hole, a second notch is arranged on the pressure release piece, the area of an area surrounded by the first notch is S1 and is smaller than the area surrounded by the second notch, and the opening pressure of the first notch is smaller than the opening pressure of the second notch. The first notch of the battery cell is opened firstly, so that more electrolyte in the battery cell can be sprayed out, the source of heat generation quantity of the electrode group in the battery cell is reduced, the strength of thermal runaway thermal reaction of the battery cell is reduced, and the safety performance of the battery cell and the battery pack is improved.

Inventors

  • LI ZHAOHUA
  • CHEN ZHENGXU
  • XU YADONG
  • QIU HEYU

Assignees

  • 蜂巢能源科技股份有限公司

Dates

Publication Date
20260505
Application Date
20260407

Claims (10)

  1. 1. A kind of electric core, characterized by comprising the following steps: A housing having a first discharge region provided with a groove to thin a thickness of the first discharge region and a second discharge region provided with a vent hole penetrating through the housing; The projection of the groove on a plane parallel to the first discharge area can cover the projection of the first notch on the plane parallel to the first discharge area; the pressure relief piece is arranged on the exhaust hole, a second notch is arranged on the pressure relief piece, the area of an area surrounded by the first notch is S1, the area of an area surrounded by the second notch is S2, S1 is less than S2, and the opening pressure of the first notch is smaller than the opening pressure of the second notch.
  2. 2. The cell of claim 1, wherein the first score is disposed corresponding to a bottom of the groove, and wherein an area of the bottom of the groove is S3; S1< S3< S2, and/or S2. Gtoreq.1.2S3, S3. Gtoreq.1.1S1, 1mm 2 ≤S1≤10mm 2 .
  3. 3. The cell of claim 1, wherein the maximum internal pressure of the cell for normal charge and discharge is P1, the opening pressure of the first score is P2, the opening pressure of the second score is P3, P3-0.2mpa > P2> p1+0.2mpa; And/or, in the cell of the LFP system, the opening pressure of the first notch is 0.4Mpa to 0.6Mpa, the opening pressure of the second notch is 0.7Mpa to 0.9Mpa, and in the cell of the NCM system, the opening pressure of the first notch is 0.5Mpa to 0.7Mpa, and the opening pressure of the second notch is 0.9Mpa to 1.5Mpa.
  4. 4. The cell of claim 1, wherein the first drain region and the second drain region are disposed on a same plane of the housing, and the recess and the vent are spaced apart.
  5. 5. The cell of claim 1, wherein the housing comprises a shell and a cover plate, wherein an open side of the shell and a circumferential edge of the cover plate are welded together; the distance between the first nick and the circumferential edge of the cover plate is d, and d is more than or equal to 3mm.
  6. 6. The cell of claim 1, wherein the housing comprises a shell and a cover plate; The first discharging area and the second discharging area are both arranged on the cover plate, a mounting hole is formed in the cover plate and used for mounting the pole, and the second discharging area is arranged on one side, far away from the mounting hole, of the first discharging area.
  7. 7. The cell of claim 1, wherein the recess is recessed from an inner wall of the housing, the first score is recessed from an outer wall of the housing, and the second score is disposed on a side of the pressure relief member facing an exterior of the cell.
  8. 8. The cell of claim 1, further comprising: the first insulating piece is arranged in the shell, a first communication hole communicated with the groove and a second communication hole communicated with the exhaust hole are formed in the first insulating piece, a first reinforcing rib is arranged on the outer side of the periphery of the first communication hole, and a second reinforcing rib is arranged in the second communication hole.
  9. 9. The cell of claim 1, wherein the vent is formed as a stepped hole having a first step and a second step, the first step having an aperture < the second step aperture, the pressure relief member being mounted to the second step.
  10. 10. A battery pack comprising the cell of any one of claims 1 to 9.

Description

Battery cell and battery pack Technical Field The invention relates to the technical field of batteries, in particular to a battery cell and a battery pack. Background The external structural member of the battery core mainly comprises a cover plate and a shell, and in the working process of the battery, particularly under the abnormal conditions of overcharge, short circuit, high temperature and the like, electrolyte can be decomposed and generate a large amount of gas, so that the internal pressure of the battery is increased, and when the pressure exceeds the pressure-resistant range of the battery shell, the shell can crack or even explode. Therefore, the cell pressure relief structure is an important safety component, and the cell pressure relief structure usually adopts an explosion-proof valve arranged on a cell cover plate or a shell, and is automatically opened before the internal pressure of the cell reaches a dangerous value so as to release internal gas to realize pressure relief, thereby avoiding physical explosion of the battery. After the electric core is in thermal runaway, the main heat generation source is the reaction and interaction of the anode material and the electrolyte. In the overcharge test process, the side reaction of the battery cell is accumulated continuously, the heat production amount or the gas production amount is in a continuously aggravated process, when the pressure of the battery cell reaches a critical value, the explosion-proof valve is opened and then part of electrolyte is sprayed out, and the overcharge can be stopped when the overcharge test is continued and a thermal runaway judgment condition is reached. The internal pressure of the battery core is higher than the external pressure, and the electrolyte sprayed out instantly after the explosion-proof valve is opened can not participate in the subsequent thermal runaway reaction to generate heat. However, after the explosion-proof valve is opened, the internal pressure and the external pressure are quickly close, so that the continuous spraying of electrolyte in the battery cell is difficult to be continuously realized, and the reduction of the thermal runaway reaction heat is not facilitated. Disclosure of Invention Accordingly, the present application is directed to a battery cell and a battery pack, which solve the problem that the explosion-proof valve ejects electrolyte at the moment of opening, and the electrolyte in the battery cell is difficult to continue to spray along with the rapid approach of the pressure inside and outside the battery cell, so that the risk of thermal runaway of the battery cell is increased. The first aspect of the present invention provides a battery cell, which comprises: A housing having a first discharge region provided with a groove to thin a thickness of the first discharge region and a second discharge region provided with a vent hole penetrating through the housing; The projection of the groove on a plane parallel to the first discharge area can cover the projection of the first notch on the plane parallel to the first discharge area; the pressure relief piece is arranged on the exhaust hole, a second notch is arranged on the pressure relief piece, the area of an area surrounded by the first notch is S1, the area of an area surrounded by the second notch is S2, S1 is less than S2, and the opening pressure of the first notch is smaller than the opening pressure of the second notch. Preferably, the first nick is arranged corresponding to the bottom of the groove, and the area of the bottom of the groove is S3; S1< S3< S2, and/or S2. Gtoreq.1.2S3, S3. Gtoreq.1.1S1, 1mm 2≤S1≤10mm2. Preferably, the maximum internal pressure of the normal charge and discharge of the battery cell is P1, the opening pressure of the first notch is P2, and the opening pressure of the second notch is P3, wherein P3-0.2mpa > P2> P1+0.2mpa; And/or, in the cell of the LFP system, the opening pressure of the first notch is 0.4Mpa to 0.6Mpa, the opening pressure of the second notch is 0.7Mpa to 0.9Mpa, and in the cell of the NCM system, the opening pressure of the first notch is 0.5Mpa to 0.7Mpa, and the opening pressure of the second notch is 0.9Mpa to 1.5Mpa. Preferably, the first discharge area and the second discharge area are disposed on the same plane of the housing, and the groove and the vent hole are disposed at intervals. Preferably, the shell comprises a shell body and a cover plate, wherein the opening side of the shell body is welded with the circumferential edge of the cover plate; the distance between the first nick and the circumferential edge of the cover plate is d, and d is more than or equal to 3mm. Preferably, the housing comprises a shell and a cover plate; The first discharging area and the second discharging area are both arranged on the cover plate, a mounting hole is formed in the cover plate and used for mounting the pole, and the second discharging area is arranged on one side,