CN111697169A

CN111697169A - Lithium battery and head

Info

Publication number: CN111697169A
Application number: CN202010554371.XA
Authority: CN
Inventors: 黄河; 宋鹏元; 王成云; 何巍; 刘金成
Original assignee: Eve Energy Co Ltd
Current assignee: Eve Energy Co Ltd
Priority date: 2020-06-17
Filing date: 2020-06-17
Publication date: 2020-09-22
Anticipated expiration: 2040-06-17
Also published as: CN111697169B

Abstract

The invention discloses a lithium battery and a seal head, wherein the lithium battery comprises a battery cell, a lug arranged at the end part of the battery cell and a seal arranged outside the battery cell; the seal comprises a protection part, and before the thermal runaway of the battery, the protection part is firstly broken than other parts except the protection part on the seal, so that the pressure relief is realized. The invention also discloses the end socket which comprises at least two hot pressing surfaces with different heights so as to form at least two positions with different thicknesses on the protection part. The invention provides a lithium battery which can break a battery seal to release pressure before thermal runaway of the battery occurs.

Description

Lithium battery and head

Technical Field

The invention relates to the technical field of lithium battery manufacturing, in particular to a lithium battery and a sealing head.

Background

The lithium battery is widely applied to the field of electrochemical energy storage by virtue of the advantages of high energy density, long service life, no memory effect, cleanness, high efficiency and the like, is particularly widely applied to electric automobiles, and has higher requirements on the safety performance of the lithium battery when the lithium battery is applied to the electric automobiles. Compared with hard-shell packaged batteries such as steel shells and aluminum shells, soft-package batteries do not have safety protection devices similar to those of hard-shell packaged batteries, so that the safety performance of soft-package lithium batteries is ensured from the aspect of electrochemical system design.

In the use process of the lithium battery, due to the variability of the external environment and the characteristics of self heating, high pressure and the like, the lithium battery is likely to generate thermal runaway, and if the seal of the battery is not broken by the soft package lithium battery before the thermal runaway, safety accidents such as explosion and the like are likely to occur. The phenomenon that the seal is difficult to break before thermal runaway can appear in soft package lithium cell at present stage to lead to soft package lithium cell to have the problem of potential safety hazard.

Disclosure of Invention

The invention aims to provide a lithium battery and a sealing head, and aims to solve the problem that the sealing seal of a soft package lithium battery provided in the background technology is difficult to break before thermal runaway, so that the soft package lithium battery has potential safety hazards.

In order to achieve the purpose, the invention adopts the following technical scheme:

a lithium battery comprises a battery cell, a tab arranged at the end part of the battery cell and a seal arranged outside the battery cell; the seal comprises a protection part, and before the thermal runaway of the battery, the protection part is firstly broken through than the rest parts except the protection part on the seal, so that the pressure relief is realized.

In an alternative embodiment of the present invention, at least two locations on the protection member have different thicknesses, so that the seal can be broken through from the locations of the protection member having the larger thickness before thermal runaway of the battery occurs.

In an alternative embodiment of the invention, the protective portion is located at the tab.

In an alternative embodiment of the invention, the thickness of the guard decreases from the middle to both sides.

In an alternative embodiment of the invention, the gradient of the decreasing thickness of the shield is 8% to 25%.

In an alternative embodiment of the present invention, two sides of the protection part are symmetrically arranged.

In an alternative embodiment of the present invention, the two sides of the protection part are asymmetrically arranged.

In an alternative embodiment of the present invention, the protective part is located on a side portion of the battery cell.

In an alternative embodiment of the present invention, the protective part is provided corresponding to an exhaust passage of the battery.

The invention also provides the end socket applied to the lithium battery, which comprises at least two hot pressing surfaces with different heights so as to form at least two positions with different thicknesses on the protection part.

The invention has the advantages that: the protection part is arranged on the seal of the battery, and before the thermal runaway of the battery, the protection part is firstly broken than other parts except the protection part on the seal, so that the pressure relief is realized, the safety accidents such as explosion of the battery are prevented, and the safety performance of the battery is improved.

Drawings

FIG. 1 is a schematic cross-sectional view of a lithium battery in an embodiment of the invention;

FIG. 2 is an exploded view of a lithium battery according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of a process for fabricating a lithium battery according to an embodiment of the present invention;

FIG. 4 is a schematic structural view of a first embodiment of a shield part according to an embodiment of the present invention;

FIG. 5 is a schematic structural diagram of a seal head in an embodiment of the invention;

FIG. 6 is a schematic view of the state of the sealing head when pressing the protecting part in the embodiment of the invention;

FIG. 7 is a schematic structural view of a second embodiment of a shield part according to an embodiment of the present invention;

FIG. 8 is a schematic structural view of a third embodiment of a guard in an embodiment of the present invention;

FIG. 9 is a schematic structural view of a fourth embodiment of a shield part according to an embodiment of the present invention;

fig. 10 is a schematic structural view of a fifth embodiment of the protective part in the embodiment of the present invention.

In the figure:

10. an electric core; 20. a tab; 30. sealing; 40. an aluminum-plastic film; 50. sealing the end;

31. a protective part.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.

In the description of the present invention, unless expressly stated or limited otherwise, the terms "connected," "connected," and "fixed" are to be construed broadly, e.g., as meaning permanently connected, removably connected, or integral to one another; can be mechanically or electrically connected; may be directly connected or indirectly connected through an intermediate. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

In the description of the present embodiment, the terms "upper", "lower", "front", "rear", "left", "rear", and the like are used in the orientations and positional relationships shown in the drawings only for convenience of description and simplification of operation, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus should not be construed as limiting the present invention.

The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached drawings.

Referring to fig. 1, the lithium battery includes a battery cell 10, tabs 20 and a seal 30, the tabs 20 are disposed at ends of the battery cell 10, and generally, the tabs 20 include positive tabs and negative tabs, which are respectively disposed at two ends of the battery cell 10 as shown in fig. 1. The seal 30 is provided outside the battery cell 10. The seal 30 is formed by the process of: referring to fig. 2 and 3, after the two aluminum-plastic films 40 cover the battery cell 10, the battery cell 10 is sandwiched between the two aluminum-plastic films 40, and hot pressing is performed at the overlapping position of the edges of the two aluminum-plastic films 40 to form a seal 30, so that the battery cell 10 is sealed in the aluminum-plastic films 40; fig. 3 only shows that the two aluminum-plastic films 40 are overlapped together, and hot pressing is not performed yet, so that the two aluminum-plastic films 40 are still separated, and after the hot pressing is completed, the peripheries of the two aluminum-plastic films 40 are all adhered together and completely sealed, and the battery cell 10 is sealed therein.

Seal 30 includes protection part 31, and before battery thermal runaway, the rest positions except protection part 31 on the seal 30 are broken through earlier, for the battery pressure release, prevent dangers such as explosion, have promoted the safety protection performance of battery.

The protection part 31 is a part with a small section of seal 30 with different thickness, please refer to fig. 4, at least two parts of the protection part 31 have different thickness, thus the seal 30 can be broken through from the part with larger thickness on the protection part 31 before the battery thermal runaway, the battery is decompressed, the dangers such as explosion and the like are prevented, and the safety protection performance of the battery is improved. The thickness difference can be realized by the sealing head 50, and during hot pressing, as shown in fig. 6, the sealing head 50 presses the edges of the aluminum-plastic films 40, and hot pressing is performed at a certain temperature for a certain time, so that the edges of the two aluminum-plastic films 40 are hot-pressed together to form the seal 30. In order to form the protective portion 31 with a thickness difference on the seal 30, as shown in fig. 5 and 6, the seal head 50 adopted by the present invention includes at least two heat pressing surfaces with different heights, and after the heat pressing surfaces with different heights contact and press the aluminum plastic film 40, a sealing edge with a non-uniform thickness, that is, the seal 30, can be formed on the protective portion 31. It can be understood that, where the protection portion 31 is not needed to be disposed on other portions of the seal 30, the thickness difference is not needed to be disposed, and then the hot pressing surface can be replaced by other flat seal heads to perform hot pressing. The seal 30 is broken from the place with the larger thickness before the thermal runaway of the battery, and the seal is broken from the place with the smaller thickness.

According to the invention, the protective part 31 can be formed on the seal 30 by directly utilizing the seal head 50 used in hot pressing, the forming is simple, and the protective part 31 is arranged on the seal 30 without any other tool or forming process change, so that the safety protection performance of the battery can be improved under the condition of not increasing higher cost, the seal 30 can be broken before thermal runaway of the battery, and safety accidents are prevented. In addition, the protective part 31 can be formed only by changing the end socket 50, which is beneficial to automatic production.

The lithium battery is suitable for any lithium battery with a seal, and is particularly suitable for a soft package lithium battery.

The effect of protection part 31 is that it breaks seal 30 from the great department of thickness to be preferential before making the battery thermal runaway, avoids the battery to take place danger such as explosion, so protection part 31 can set up the optional position on the battery, for example protection part 31 can be located utmost point ear 20 department, and the temperature of utmost point ear 20 department is higher than the temperature on electric core 10 surface, and seal 30 of battery generally appears the deblocking at utmost point ear 20 department first, sets up protection part 31 can be favorable to battery break seal 30 in utmost point ear 20 department. Specifically, the protection portion 31 may be disposed at the positive tab or the negative tab, and is not limited herein, and the temperatures at the positive tab and the negative tab are relatively high, and both are suitable for disposing the protection portion 31.

Of course, the protective part 31 may be located at a side portion of the battery cell 10, for example, the protective part 31 may be disposed at any position around the battery cell 10.

In addition, the guard portion 31 may be provided corresponding to the exhaust passage of the battery. Generally, the battery is internally provided with an exhaust passage for exhausting gas in the battery, the protection part 31 is arranged corresponding to the exhaust passage, and the seal 30 can be broken by utilizing the gas exhausted from the battery exhaust passage, so that the safety performance of the battery can be improved.

Fig. 4 is a schematic structural view of a first embodiment of the protective part in the embodiment of the present invention, and as shown in fig. 4, the thickness of the protective part 31 decreases from the middle to both sides to form a thickness difference. The protection part 31 shown in fig. 4 has a plurality of places with different thicknesses, and in practical implementation, it is only required to ensure that at least two places with different thicknesses are different, that is, a position with a larger thickness is arranged on the protection part 31, so that the battery can preferentially break the seal 30 from the place with the larger thickness. In the embodiment shown in fig. 7, only two positions on the protection portion 31 are shown with different thicknesses.

It is understood that the thickness of the guard 31 may also vary continuously rather than decreasing, as shown in fig. 8.

In addition, as shown in fig. 4, when the thickness of the protection portion 31 decreases toward both sides, the decreasing gradient is 8% to 25%, that is, the thickness decreases by 8% to 25% on the original basis every time of decreasing, so that the degree of decreasing is not large every time, and the strength of the whole protection portion 31 can be ensured.

Referring to fig. 4, the two sides of the protection portion 31 are symmetrically disposed, and the thickness decreases from the middle to the two sides in a symmetrical manner. The symmetrical arrangement of the protection part 31 not only makes the stress of the protection part 31 more symmetrical, but also facilitates the arrangement of the seal head 50, makes the hot pressing surface on the seal head 50 more symmetrical, and facilitates the manufacture of the seal head 50.

As shown in fig. 4, the thickness of the guard portion 31 is decreased by 10% and 23% in order from the middle to both sides. Let the thickness of the middle of the protection part 31 be a, the thickness of the position adjacent to the middle be b, and the thickness of the two sides be c, wherein b is 0.9 a; c is 0.77b, b is reduced by 10% on a basis, and c is reduced by 23% on b basis.

As shown in fig. 9, both sides of the protector 31 may be asymmetric, and may have a difference in thickness.

The thickness of the protection portion 31 does not necessarily decrease or increase as shown in fig. 10, but may increase or decrease irregularly, and the thickness of the protection portion 31 decreases from left to right and then increases and then decreases and then increases as shown in fig. 10.

The invention also provides a seal head applied to the lithium battery, and the structure of the seal head 50 is shown in fig. 5 and comprises at least two hot pressing surfaces with different heights, so that at least two parts with different thicknesses are formed on the protection part 31, the protection part 31 is provided with a part with a thicker thickness, the lithium battery can break the seal 30 from the part with the thicker thickness on the protection part 31 before thermal runaway, the pressure of the battery is relieved, and the safety performance of the battery is ensured.

It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Numerous obvious variations, adaptations and substitutions will occur to those skilled in the art without departing from the scope of the invention. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A lithium battery is characterized by comprising a battery core (10), a pole lug (20) arranged at the end part of the battery core (10), and a seal (30) arranged outside the battery core (10); the seal (30) comprises a protection part (31), and before the thermal runaway of the battery, the protection part (31) is firstly broken than other parts of the seal (30) except the protection part (31) so as to realize the pressure relief.

2. A lithium battery as claimed in claim 1, characterized in that the protective part (31) has at least two portions of different thickness, so that the seal (30) can be broken through from the portions of greater thickness of the protective part (31) before thermal runaway of the battery.

3. A lithium battery as claimed in claim 2, characterized in that the protective part (31) is located at the tab (20).

4. A lithium battery as claimed in claim 3, characterized in that the thickness of the protective part (31) decreases from the middle to both sides.

5. Lithium battery as claimed in claim 4, characterized in that the gradient of the decreasing thickness of the protective part (31) is 8-25%.

6. Lithium battery according to claim 4, characterized in that the two sides of the guard (31) are symmetrically arranged.

7. Lithium battery according to claim 4, characterized in that the two sides of the guard (31) are arranged asymmetrically.

8. A lithium battery as claimed in claim 2, characterized in that the protective part (31) is located at the side of the cell (10).

9. A lithium battery as claimed in claim 2, characterized in that the protective part (31) is arranged in correspondence with an air exhaust channel of the battery.

10. A header for a lithium battery as claimed in any one of claims 2 to 9, characterized in that it comprises at least two hot-pressing surfaces of different height to form at least two spots of different thickness on the shield (31).