CN220492122U

CN220492122U - Battery cell

Info

Publication number: CN220492122U
Application number: CN202322040932.6U
Authority: CN
Inventors: 靳玲玲; 李俊义; 刘建明
Original assignee: Zhejiang Guanyu Battery Co ltd
Current assignee: Zhejiang Guanyu Battery Co ltd
Priority date: 2023-07-31
Filing date: 2023-07-31
Publication date: 2024-02-13
Anticipated expiration: 2033-07-31

Abstract

The application provides a battery, the battery includes shell, electric core and explosion-proof piece, and the shell has accommodation cavity and pressure release through-hole, and the electric core sets up in accommodation cavity, and pressure release through-hole communicates in accommodation cavity and accommodation cavity outside; the explosion-proof piece is positioned in the pressure relief through hole and is welded and connected with the shell, a welding line is arranged at the welding joint of the explosion-proof piece and the shell, at least part of the welding line is positioned in the explosion-proof piece, at least part of the welding line is positioned in the shell, the welding line comprises a total melting width and an effective melting width, and the total melting width is W ₁ The effective melting width is W ₂ Wherein, the method comprises the steps of, wherein,the battery has good sealing performance and explosion performance.

Description

Battery cell

Technical Field

The application relates to the technical field of batteries, in particular to a battery.

Background

Under the large background of global energy conservation, emission reduction and sustainable development, new energy is a good choice for replacing fossil energy, and the new energy lithium battery technology is widely applied to the fields of automobiles, heavy trucks, agricultural unmanned aerial vehicles, electric tools and the like at present, and the lithium battery has the characteristics of high energy density, long cycle life, no memory effect, environmental friendliness and the like and is widely applied to plug-in hybrid electric vehicles, pure electric vehicles, signal tower stations and the like.

The lithium battery generally comprises a battery core and electrolyte, wherein the battery core and the electrolyte are packaged inside a shell together, the lithium battery can produce gas in the lithium battery in the manufacturing and using processes, if the lithium battery is not discharged and decompressed in time, the explosion and the fire risk can occur, therefore, the lithium battery can further comprise a detonation device, when the pressure in the lithium battery reaches a threshold value, the detonation device is separated from the shell, partial gas is discharged to reduce the pressure in the battery, in the related art, the detonation device is connected with the shell of the battery in a welding way, and the sealing property and the compressive strength of the battery can be influenced due to the welding quality of the detonation device and the shell, so that the welding reliability of the detonation device is still a problem to be solved urgently.

Disclosure of Invention

Based on this, the present application provides a battery to solve the deficiencies in the related art.

The application provides a battery, the battery includes shell, electric core and explosion-proof piece, and the shell has accommodation cavity and pressure release through-hole, and the electric core sets up in accommodation cavity, and pressure release through-hole communicates in accommodation cavity and accommodation cavity outside;

the explosion-proof piece is positioned in the pressure relief through hole and is welded and connected with the shell, a welding line is arranged at the welding joint of the explosion-proof piece and the shell, at least part of the welding line is positioned in the explosion-proof piece, at least part of the welding line is positioned in the shell, the welding line comprises a total melting width and an effective melting width, and the total melting width is W ₁ The effective melting width is W ₂ Wherein, the method comprises the steps of, wherein,

in one possible implementation, the battery provided herein has a total and effective melting width ranging from: w is more than or equal to 0.3mm ₂ ≤W ₁ ≤3mm。

In one possible implementation, the battery provided herein further includes a total penetration, where the total penetration is T ₁ Wherein W is ₂ ≤T ₁ ≤W ₁ 。

In one possible implementation, the battery provided by the present application, the weld further includes an effective penetration, where the effective penetration is T ₂ Wherein T is more than or equal to 0.3mm ₂ ≤T ₁ ≤1.5mm。

In one possible implementation, the cross-sectional shape of the weld provided herein includes semi-circular, sharp triangular, trapezoidal, bi-peaked, and cylindrical.

In one possible implementation, the battery provided herein, the explosion proof member is welded to the housing by one of laser pulse welding and laser connection welding.

In one possible implementation manner, the battery provided by the application comprises a shell, a top cover and a battery cover, wherein the top cover is covered on and connected with the shell to jointly enclose a containing cavity;

the pressure release through hole is arranged on one of the top cover and the main shell.

In one possible implementation manner, the battery provided by the application, the explosion-proof piece is welded on one side of the top cover facing the accommodating cavity, or the explosion-proof piece is welded on one side of the main shell facing away from the accommodating cavity.

In one possible implementation manner, the battery provided by the application, the explosion-proof piece is provided with at least one groove along the thickness direction, the bottom wall thickness of the groove is greater than or equal to 0.03mm, and the bottom wall thickness of the groove is less than or equal to 2mm.

In one possible implementation, the battery provided herein has a hardness of the explosion-proof member greater than or equal to 20HV and a hardness of the explosion-proof member less than or equal to 35HV.

In one possible implementation, the battery provided herein has an expansion of 20% or greater of the explosion-proof component.

In one possible implementation manner, the battery provided by the application, the pressure release through hole comprises a first communication section and a second communication section which are communicated with each other, the cross-sectional area of the first communication section along the extending direction of the pressure release through hole is larger than the cross-sectional area of the second communication section along the extending direction of the pressure release through hole, and the explosion-proof piece is arranged on the first communication section;

the thickness of the explosion-proof piece is smaller than or equal to the depth of the first communication section, and the depth of the first extension section is larger than or equal to 0.3mm and smaller than or equal to 2mm.

The battery that this application provided, including shell, electric core and explosion-proof piece, be used for forming through setting up the shell and hold the chamber to hold electric core and electrolyte, be used for releasing pressure when holding chamber pressure too big through setting up the pressure release through-hole at the shell, be used for sealing the pressure release through-hole through setting up the explosion-proof piece at the pressure release through-hole, and open the pressure release when holding the pressure of chamber too big, through making explosion-proof piece and shell welded connection, and make the total width W of fusion of welding seam ₁ And effective melting width W ₂ The method meets the following conditions:and further, the welding strength and the sealing performance of the explosion-proof piece and the shell are ensured, and electrolyte can be prevented from leaking from the welding connection position of the explosion-proof piece and the shell. Therefore, the battery has better sealing performance.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief description will be given below of the drawings that are needed in the embodiments or the prior art descriptions, and it is obvious that the drawings in the following description are some embodiments of the present application, and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a schematic structural diagram of a battery according to an embodiment of the present disclosure;

fig. 2 is a schematic structural view of a top cover, an explosion-proof member, a sealing member, a protective patch, a pole and a switching piece in a battery according to an embodiment of the present application;

fig. 3 is a schematic structural view of a top cover and an explosion-proof member in a battery according to an embodiment of the present application;

fig. 4 is a schematic structural diagram of a casing and an explosion-proof member in a battery according to an embodiment of the present application;

FIG. 5 is a schematic view of a partial structure of a housing, an explosion proof member, and a weld in an embodiment of the present application;

fig. 6 is a schematic structural diagram of a top cover in a battery according to an embodiment of the present disclosure;

fig. 7 is a schematic structural diagram of an explosion-proof component in a battery according to an embodiment of the present application;

fig. 8 is a flow chart of a method for manufacturing a battery according to an embodiment of the present disclosure.

Reference numerals illustrate:

100-a housing; 110-a pressure relief through hole; 111-a first communication section; 112-a second communication section; 120-main shell; 130-top cap; 140-a receiving cavity; 200-explosion-proof parts; 210-groove; 300-cell; 400-welding; 500-pole; 600-switching piece; 700-seal; 800-protective patch.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the present application more apparent, the technical solutions in the embodiments of the present application will be described in more detail below with reference to the accompanying drawings in the preferred embodiments of the present application. In the drawings, the same or similar reference numerals refer to the same or similar components or components having the same or similar functions throughout. The described embodiments are some, but not all, of the embodiments of the present application. The embodiments described below by referring to the drawings are exemplary and intended for the purpose of explaining the present application and are not to be construed as limiting the present application. All other embodiments, which can be made by one of ordinary skill in the art based on the embodiments herein without making any inventive effort, are intended to be within the scope of the present application. Embodiments of the present application are described in detail below with reference to the accompanying drawings.

In the description of the present application, it should be noted that, unless explicitly stated and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, indirectly connected through an intermediary, in communication between two elements, or in an interaction relationship between two elements. The specific meaning of the terms in this application will be understood by those of ordinary skill in the art as the case may be.

In the description of the present application, it should be understood that the terms "upper," "lower," "front," "rear," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like indicate an orientation or a positional relationship based on the drawings, which are merely for convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present application.

The terms "first," "second," "third" (if any) in the description and claims of the present application and in the above-described figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that embodiments of the present application described herein may be capable of operation in sequences other than those illustrated or described herein, for example.

Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or display that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed but may include other steps or elements not expressly listed or inherent to such process, method, article, or display.

Lithium battery generally includes electric core and electrolyte, electric core and electrolyte encapsulate inside the shell together, if the leakproofness of shell is insufficient, can lead to the electrolyte to reveal, and then influence lithium battery's performance and safety, lithium battery is in manufacturing and use simultaneously, lithium battery inside can produce gas, battery internal pressure is too big under the good circumstances of leakproofness, if not in time discharge pressure release, there is the danger of explosion fire, therefore, in the correlation technique, lithium battery can set up a detonating device, detonating device and the shell welded connection of battery, in order to enclose into confined inner space jointly with the shell, and when the inside pressure of lithium battery reaches certain degree, detonating device can be opened, in order to form the gas leakage mouth, and then make the inside gas of battery flow from the gas leakage mouth, thereby reduce battery internal pressure.

It should be noted that, the welding strength between the initiating device and the shell cannot be too high, otherwise, the welding area is not only easy to be penetrated, so that the sealability between the initiating device and the shell is lost, and secondly, the thermal influence is too high, the stability of opening the initiating device can be influenced, the initiating device cannot be opened for pressure relief at a proper time, and in addition, the high welding strength is pursued uniformly, so that heat waste is generated, and the processing cost of the battery is increased. On the other hand, the welding strength between the detonating device and the casing cannot be too low, otherwise, the sealing performance between the detonating device and the casing is insufficient, and electrolyte leakage is easy to cause.

In the related art, a shell and an initiating device of the power battery are both stamping parts with thinner thickness, and stamping parts are easy to remain stamping oil, cleaning liquid and the like during stamping processing. In the subsequent welding process of the detonating device and the shell, the residual liquid is extremely easy to be vaporized by heat during welding, floats to the surface of a molten pool, splashes in a large amount while bursting, and pits are left on the surface of the welding line to form blastholes. On the other hand, the detonation device is extremely easy to generate thermal deformation and warpage during welding due to the thinner thickness, and a large amount of air exists in an assembly gap between the detonation device and the shell. This residual air expands when heated during welding and the tendency for hole-explosion defects to form is further exacerbated by the squirting melt pool. These drawbacks affect the weld strength of the initiator and the housing, which in turn affects the sealability of the battery. Therefore, how to effectively ensure the welding strength between the detonation device and the shell, so that the welding strength is not too high or too low, is a problem to be solved.

Furthermore, it is also an important issue how to give the priming device a better blasting performance. That is, the priming device needs to have good sealability to prevent leakage of the electrolyte. And the detonating device needs to have good blasting performance so as to avoid the risks of reduced service life and explosion and ignition of the battery caused by early or delayed starting or even no starting of the battery in the use process.

In view of the above, embodiments of the present application provide a battery including a case and an explosion-proof member welded to the case and formed by welding a total width W and an effective width W of a weld ₂ The relationship between them is set as:and the welding strength between the explosion-proof piece and the shell is moderate, so that the balance among the tightness of the battery, the processing cost of the battery and the opening stability of the explosion-proof piece is achieved.

Specific embodiments of a battery provided in the examples of the present application are described in detail below with reference to the accompanying drawings.

Referring to fig. 1 to 7, the embodiment of the present application provides a battery, which includes a housing 100, a battery cell 300 and an explosion-proof member 200, wherein the housing 100 has a receiving cavity 140 and a pressure release through hole 110, the battery cell 300 is disposed in the receiving cavity 140, and the pressure release through hole 110 is communicated in the receiving cavity 140 and outside the receiving cavity 140.

The explosion-proof piece 200 is positioned at the pressure relief through hole 110 and is welded and connected with the shell 100, a welding line 400 is arranged at the welding joint of the explosion-proof piece 200 and the shell 100, at least part of the welding line 400 is positioned at the explosion-proof piece 200, at least part of the welding line 400 is positioned at the shell 100, the welding line 400 comprises a total melting width and an effective melting width, and the total melting width is W ₁ The effective melting width is W ₂ Wherein, the method comprises the steps of, wherein,

the explosion-proof member 200 may be welded to the pressure relief through hole 110 by laser pulse welding or laser connection welding.

Note that, the total width of the weld 400 is the total width of the weld 400 in the width direction, and the width direction of the weld 400 may refer to the X direction in fig. 5.

Since there may be an assembly error when the explosion-proof member 200 and the case 100 are spliced before welding, and since there is a cold welding phenomenon when welding, the effective width of the welding seam 400 when the explosion-proof member 200 and the case 100 are welded may be smaller than the total width of the welding seam 400, that is, the effective melting width of the welding seam 400 is smaller than or equal to the total melting width.

In order to ensure the welding strength of the explosion-proof member 200 and the casing 100 and the tightness after welding, the effective melting width is greater than or equal to one third of the total melting width, if the effective melting width is less than one third of the total melting width, the effective width of the welding seam 400 is insufficient, so that the welding strength between the two is lower and the sealing performance is poorer, therefore, the effective melting width is greater than or equal to one third of the total melting width, the moderate welding strength between the explosion-proof member 200 and the casing 100 can be ensured, the sealing performance between the explosion-proof member 200 and the casing 100 is better, electrolyte is not easy to leak, the processing cost of a battery is not increased, and meanwhile, the explosion-proof member 200 has good explosion performance, and the explosion-proof member 200 can be timely separated from the casing 100 when the internal pressure of the battery is over-high so as to open the pressure relief.

The battery provided by the application, including shell 100, electric core 300 and explosion-proof piece 200, be used for forming through setting up shell 100 and hold chamber 140, with hold electric core 300 and electrolyte, through setting up pressure release through-hole 110 at shell 100 and be used for releasing pressure when holding chamber 140 pressure too big, through setting up explosion-proof piece 200 and be used for sealing pressure release through-hole 110 at pressure release through-hole 110, and open the pressure release when holding chamber 140 pressure too big, through making explosion-proof piece 200 and shell 100 welded connection, and make the total width of fusion of welding seam 400 be W ₁ And the effective melting width is W ₂ The method meets the following conditions:further, the welding strength and sealing performance of the explosion-proof member 200 and the housing 100 are ensured, and leakage of the electrolyte from the welding joint of the explosion-proof member 200 and the housing 100 can be prevented. Therefore, the battery has better sealing performance.

In order to achieve better explosion performance of the explosion-proof component 200, referring to fig. 8, specifically, an embodiment of the present application further provides a method for manufacturing a battery, which includes:

s101, determining the detonation pressure of the battery.

Before the battery is manufactured, the detonation pressure of the battery, that is, the maximum pressure that the battery can bear, needs to be determined, and when the pressure inside the battery exceeds the detonation pressure, the battery can explode and fire. Therefore, when the pressure inside the battery reaches the detonation pressure, the casing 100 of the battery should form the pressure release through hole 110, so that part of the gas flows out of the pressure release through hole 110, thereby reducing the pressure inside the battery and preventing the pressure inside the battery from continuously rising, so as to avoid the explosion and the fire of the battery and cause safety accidents.

It should be understood that the maximum pressure that can be sustained by different types of batteries is different, for example, the detonation pressure of the battery may be set between 0.1Mpa and 5.0Mpa, and further, in order to achieve better explosion performance of the explosion-proof member 200, the detonation pressure of the battery may be set between 0.3Mpa and 2.5 Mpa.

Wherein the thickness of the housing 100 may be set between 0-10 mm.

S102, determining explosion parameters of the explosion-proof piece 200 of the battery according to the explosion pressure of the battery, wherein the explosion parameters comprise at least one of the residual thickness of the explosion-proof piece 200 and the hardness of the explosion-proof piece 200.

That is, the residual thickness of the explosion-proof member 200 and the hardness of the explosion-proof member 200 may be determined according to the explosion-initiation pressure of the battery, or the residual thickness of the explosion-proof member 200 or the hardness of the explosion-proof member 200 may be determined according to the explosion-initiation pressure of the battery.

Thus, the hardness of the explosion-proof piece 200 is determined based on the detonation pressure of the battery, so that the hardness of the explosion-proof piece 200 can be matched with the detonation pressure to prevent the explosion-proof piece 200 from being lower, when the pressure in the battery does not reach the detonation pressure, the explosion-proof piece 200 is exploded under the action of the pressure, or the hardness of the explosion-proof piece 200 is prevented from being higher, when the pressure in the battery reaches the detonation pressure, the explosion-proof piece 200 is still not exploded, the pressure in the battery is continuously increased, and finally the explosion of the battery is caused to fire.

The residual thickness of the explosion-proof piece 200 is determined based on the detonation pressure of the battery, so that the residual thickness of the explosion-proof piece 200 can be matched with the detonation pressure, the residual thickness of the explosion-proof piece 200 is prevented from being smaller, when the pressure in the battery does not reach the detonation pressure, the explosion-proof piece 200 is blasted and penetrated under the action of the pressure, or the residual thickness of the explosion-proof piece 200 is prevented from being larger, after the pressure in the battery reaches the detonation pressure, the explosion-proof piece 200 is still not blasted and penetrated, the pressure in the battery is continuously increased, and finally the explosion of the battery is caused to fire.

The explosion-proof component 200 is provided with at least one groove 210, the casing 100 is provided with a pressure relief through hole 110, the groove 210 may be disposed on a side of the explosion-proof component 200 facing the inner side of the casing 100, or the groove 210 may be disposed on a side of the explosion-proof component 200 facing the outer side of the casing 100.

For example, when the number of the grooves 210 is two and the grooves 210 are disposed on one side of the explosion-proof member 200 facing the outer side of the casing 100, the residual thickness T of the explosion-proof member 200 is the thickness of the bottom wall of the groove 210 facing away from the outer side of the casing 100, as shown in fig. 7, after the residual thickness of the explosion-proof member 200 is determined according to the detonation pressure of the battery, when the internal pressure of the battery does not reach the detonation pressure, the bottom wall of the groove 210 is blasted and penetrated due to the fact that the bottom wall of the groove 210 has a certain thickness, and when the internal pressure of the battery reaches the detonation pressure, the part where the bottom wall of the groove 210 is the thinnest part in the overall structure of the explosion-proof member 200 is blasted and penetrated due to the pressure, so that the pressure release through hole 110 is opened to communicate the battery interior with the battery exterior, thereby reducing the pressure inside the battery.

Wherein the bottom wall thickness of the recess 210 facing away from the outside of the housing 100 is smaller than the bottom wall thickness of the recess 210 adjacent to the outside of the housing 100, and both are between 0.03-2 mm.

Therefore, the explosion parameters of the explosion-proof piece 200 are determined according to the explosion pressure of the battery, so that the explosion-proof piece 200 cannot be exploded and penetrated when the pressure of the explosion-proof piece 200 in the battery does not reach the explosion pressure, and the explosion-proof piece 200 is exploded and penetrated when the pressure of the explosion-proof piece 200 in the battery reaches the explosion pressure, the pressure release through hole 110 of the shell 100 is opened, and the explosion-proof piece 200 is prevented from opening the pressure release through hole 110 in advance or the explosion-proof piece 200 is prevented from opening the pressure release through hole 110 in a delayed manner.

S103, determining the explosion-proof piece 200 according to the explosion parameters of the explosion-proof piece 200, and installing the explosion-proof piece 200 on the shell 100 of the battery to form the battery.

After the explosion parameters of the explosion-proof member 200 are determined, the explosion-proof member 200 can be manufactured according to the explosion parameters, and the explosion-proof member 200 is welded to the housing 100 of the battery, so that the explosion-proof member 200 and the housing 100 together form a sealed battery internal space, and when the battery is used for a period of time and the pressure in the battery reaches the explosion pressure, the explosion-proof member 200 can be exploded under the action of the pressure, so that the interior of the housing 100 is communicated with the exterior of the housing 100.

In one possible implementation, determining the explosion parameters of the explosion proof member 200 from the detonation pressure of the battery includes:

s1021, calculating and obtaining the residual thickness of the explosion-proof piece 200 based on a first formula according to the detonation pressure of the battery, wherein the first formula comprises:

T＝(P+a)/b

where T is the residual thickness of the explosion-proof component 200, P is the detonation pressure of the battery, and a and b are constants.

Illustratively, a may be 0.55 and b may be 12.5.

Thus, after the type of the battery is determined and the detonation pressure of the battery is determined according to the type of the battery, the residual thickness of the explosion-proof member 200 can be calculated according to the first formula, and the explosion-proof member 200 is provided with the groove 210 to control the residual thickness of the explosion-proof member 200 by controlling the thickness of the bottom wall of the groove 210, so that the processing depth of the groove 210 can be accurately controlled when the groove 210 is processed on the explosion-proof member 200, thereby accurately controlling the residual thickness of the explosion-proof member 200 to match the residual thickness of the explosion-proof member 200 with the detonation pressure of the battery.

In one possible implementation, determining the explosion parameters of the explosion proof member 200 from the firing pressure of the battery includes:

s1022, calculating and obtaining the hardness of the explosion-proof piece 200 based on a second formula according to the detonation pressure of the battery, wherein the second formula comprises:

H＝(P+c)/d

where H is the hardness of the explosion-proof component 200, P is the detonation pressure of the battery, and c and d are constants.

Illustratively, a may be-0.52 and b may be 0.013.

In this way, after the type of the battery is determined and the detonation pressure of the battery is determined according to the type of the battery, the hardness of the explosion-proof member 200 can be calculated according to the second formula, so that the hardness of the explosion-proof member 200 can be accurately controlled by selecting the material of the explosion-proof member 200 so that the hardness of the explosion-proof member 200 matches the detonation pressure of the battery.

In some embodiments, the residual thickness of the explosion proof piece 200 is greater than or equal to 0.03mm, and the residual thickness of the explosion proof piece 200 is less than or equal to 2mm.

It will be appreciated that if the residual thickness of the explosion-proof member 200 is less than 0.03mm, the bottom wall of the recess 210 is thinner, the detonation pressure of the battery is between 0.1Mpa and 5.0Mpa, the bottom wall of the recess 210 is easy to be blasted and penetrated before the pressure inside the battery does not reach the detonation pressure, so as to cause the explosion-proof member 200 to be opened in advance, if the residual thickness of the explosion-proof member 200 is greater than 2mm, the bottom wall of the recess 210 is thicker, and after the pressure inside the battery reaches the detonation pressure, the bottom wall of the recess 210 is still not blasted and penetrated, so as to cause the explosion-proof member 200 to be opened in a delayed manner.

Accordingly, setting the residual thickness of the explosion-proof member 200 to be between 0.03mm and 2mm can ensure that the explosion-proof member 200 is exploded open at an appropriate time to open the pressure relief through hole 110.

Regarding the numerical ranges and numerical ranges, it should be noted that the numerical ranges and numerical ranges referred to in the embodiments of the present application are approximations, and may be affected by the manufacturing process, and some errors may exist, which may be considered negligible by those skilled in the art.

For example, in order to ensure production uniformity of the explosion proof member 200, a tolerance range of the residual thickness of the explosion proof member 200 may be set to-0.02 mm to 0.02mm.

As an alternative embodiment, the thickness of the explosion proof member 200 is less than or equal to the wall thickness of the housing 100, the thickness of the explosion proof member 200 is greater than or equal to 0.3mm, and the thickness of the housing 100 is less than or equal to 2mm.

That is, the thickness of the explosion-proof member 200 needs to be set between 0.3mm and 2mm to ensure the production yield and productivity of the explosion-proof member 200 in production and manufacture, and to facilitate the mounting of the explosion-proof member 200 to the housing 100, the thickness of the explosion-proof member 200 needs to be made smaller than or equal to the thickness of the housing 100, wherein the thickness of the housing 100 may be set between 0.3 and 2mm.

In one possible implementation, the hardness of the explosion proof member 200 is greater than or equal to 20HV, and the hardness of the explosion proof member 200 is less than or equal to 35HV. In this way, setting the hardness of the explosion-proof member 200 between 20HV and 35HV can ensure the consistency and manufacturability of the explosion-proof member 200.

As an alternative embodiment, the expansion ratio of the explosion proof member 200 is greater than or equal to 20%. Since the explosion penetration of the explosion-proof member 200 is also affected by the expansion rate of the explosion-proof member 200, the explosion-proof member 200 may be made of aluminum, and in order to ensure that the explosion-proof member 200 is reliably exploded and penetrated when the pressure inside the battery reaches the explosion pressure, the expansion rate of the explosion-proof member 200 needs to be 20% or more.

In one possible implementation, the welded connection of the explosion proof piece 200 and the housing 100 has a weld 400, at least a portion of the weld 400 is located at the explosion proof piece 200, and at least a portion of the weld 400 is located at the housing 100.

That is, the weld 400 may be biased toward the explosion proof member 200, and the weld 400 may be biased toward the case 100, but it should be ensured that at least part of the weld 400 is located at the explosion proof member 200 and at least part of the weld 400 is located at the case 100 to prevent the occurrence of a cold joint or a broken joint between the explosion proof member 200 and the case 100, thereby resulting in poor sealability of the battery.

Referring to fig. 5, in one possible implementation, the total and effective widths range from: w is more than or equal to 0.3mm ₂ ≤W ₁ ≤5mm。

That is, when the total and effective widths satisfy:when the welding seam 400 meets the requirement, the welding energy is not excessively dispersed, and the welding seam 400 can be effectively connected with the shell 100 and the explosion-proof piece 200, so that the strength and the tightness of the welding seam 400 are effectively ensured.

Further, the total and effective widths satisfy:to ensure good sealing of the battery.

With continued reference to FIG. 5, in some embodiments, the weld 400 further includes a total penetration, T ₁ Wherein W is ₂ ≤T ₁ . In this way, the effective melting width of the welding seam 400 is smaller than or equal to the total melting depth, and the welding strength and the sealing performance of the welding seam 400 can be effectively ensured. Wherein the depth direction of the weld 400 may refer to the Y direction in fig. 5.

It will be appreciated that the total penetration should be less than 3mm to avoid welding through the housing 100 or the explosion proof member 200, that is:to improve sealability of the battery.

In order to meet the strength and sealing performance after welding, the shape of the weld pool after connecting the vertexes should be an isosceles triangle or an isosceles trapezoid, the base angle of the isosceles triangle or the isosceles trapezoid changes between 30 degrees to 60 degrees, the total melting width is equivalent to the base of the isosceles triangle or the isosceles trapezoid, and the total melting depth is equivalent to the height of the isosceles triangle or the isosceles trapezoid, so the total melting width should be smaller than or equal to the total melting depth. Namely, the relation among the total melting width, the effective melting depth and the total melting depth is as follows: w (W) ₂ ≤T ₁ ≤W ₁ 。

Because assembly errors exist when the explosion-proof piece 200 and the housing 100 are spliced before welding, and because a cold welding phenomenon exists during welding, the effective depth of the welding seam 400 when the explosion-proof piece 200 and the housing 100 are welded is smaller than the total depth of the welding seam 400, namely the effective depth of the welding seam 400The penetration is less than or equal to the total penetration, and the effective penetration is marked as T ₂ Wherein T is more than or equal to 0.3mm ₂ ≤T ₁ ≤1.5mm。

It will be appreciated that if the effective width of the weld 400 is less than 0.3mm, the weld 400 is insufficient to connect the explosion proof member 200 and the housing 100 at the same time, and if the effective width of the weld 400 is greater than 3mm, the weld line energy of the weld 400 may be too dispersed to connect the explosion proof member 200 and the housing 100. If the effective penetration of the weld 400 is less than 0.3mm, the weld 400 is insufficient to simultaneously connect the explosion-proof member 200 and the case 100, and if the effective penetration of the weld 400 is greater than 1.5mm, the weld line energy of the weld 400 is excessively dispersed, which is unfavorable for connecting the explosion-proof member 200 and the case 100.

Therefore, the effective melting width of the welding seam 400 is set between 0.3mm and 3mm, and the effective melting depth of the welding seam 400 is set between 0.3mm and 1.5mm, so that effective welding between the explosion-proof piece 200 and the shell 100 can be ensured, and the welding connection performance between the explosion-proof piece 200 and the shell 100 is good, thereby improving the yield of the battery and reducing the manufacturing cost of the battery.

For example, the effective width of the weld 400 may be set between 0.5mm and 3 mm.

Before testing the effective width and the total width of the weld 400, the weld 400 needs to be cleaned, the weld 400 is cut in sections, polishing, cleaning, corrosion, drying and the like are performed on the weld 400, and then an imaging device or a measuring ruler is used for measuring the effective width, the total width, the effective penetration and the total penetration of the weld 400.

Illustratively, taking the semicircular weld 400 shown in FIG. 5 as an example, after obtaining the cross-section of the weld 400 shown in FIG. 5, the total width W can be obtained by measuring the distance between the two points AB ₁ Projecting the point C onto the AB straight line, and measuring the distance between the projection point of the C on the AB straight line and the point B to obtain the effective melting width W ₂ Measuring the distance between the two DE points to obtain the total penetration T ₁ Measuring the distance between the DF two points to obtain the effective penetration T ₂ . The above description does not limit the cross-sectional shape of the weld 400.

In one possible implementation, the cross-sectional shape of the weld 400 includes semi-circular, sharp triangular, trapezoidal, bi-peaked, and cylindrical. The weld 400 in the various forms can effectively ensure that the total width, the effective width, the total penetration and the effective penetration of the weld 400 meet the requirements, thereby ensuring the firmness and the tightness of the weld 400.

Referring to fig. 2 and 5, in the embodiment, the housing 100 includes a main housing 120 and a top cover 130, where the top cover 130 covers and is connected to the main housing 120 to jointly enclose a receiving chamber 140, and the pressure relief through hole 110 is disposed in the top cover 130 or the main housing 120.

It is understood that the case 100 may have a cylindrical shape or a square shape, and the explosion-proof member 200 may be first welded to the top cap 130 or the main case 120 and then the top cap 130 is welded to the main case 120 to encapsulate the battery cell 300 inside the case 100 at the time of production. When the pressure inside the casing 100 reaches the detonation pressure, the explosion-proof member 200 is exploded to open the pressure release through-hole 110, thereby communicating the inside and the outside of the accommodating chamber 140.

In one possible implementation, the explosion proof member 200 is welded to the side of the top cover 130 facing the receiving chamber 140, or the explosion proof member 200 is welded to the side of the main case 120 facing away from the receiving chamber 140.

It should be noted that, the pressure relief through hole 110 may include a first communication section 111 and a second communication section 112 that are mutually communicated, and a cross-sectional area of the first communication section 111 along an extending direction of the pressure relief through hole 110 is greater than a cross-sectional area of the second communication section 112 along the extending direction of the pressure relief through hole 110, and the explosion-proof component 200 is disposed on the first communication section 111.

In order to ensure the consistency of assembly to improve the production efficiency and the production yield, the thickness of the explosion-proof member 200 may be made smaller than or equal to the depth of the first communication section 111, and the depth of the first communication section 111 is greater than or equal to 0.3mm and smaller than or equal to 2mm.

It will be appreciated that after the explosion proof member 200 is welded within the first communication section 111, the surface of the explosion proof member 200 facing away from the second communication section 112 should be lower than the end surface of the first communication section 111 facing away from the second communication section 112 or flush with the end surface of the first communication section 111 facing away from the second communication section 112. That is, when the pressure relief through hole 110 is disposed on the top cover 130, the first communication section 111 is disposed on one end of the pressure relief through hole 110 facing the accommodating cavity 140, and when the pressure relief through hole 110 is disposed on the main casing 120, the first communication section 111 is disposed on one end of the pressure relief through hole 110 facing away from the accommodating cavity 140, so as to facilitate welding the explosion-proof member 200 and the top cover 130, or facilitate welding the explosion-proof member 200 and the main casing 120.

In addition, referring to fig. 3, the battery may further be provided with a tab 500 and a tab 600, the tab 500 including a tab 500 of a positive electrode and a tab 500 of a negative electrode, the tab 600 including a tab 600 of a positive electrode and a tab 600 of a negative electrode, the tab 600 being connected between the battery cell 300 and the tab 500 for guiding out current of the battery cell 300, the tab 500 being for electrical connection with a device to be powered, and a seal 700 for sealing a gap between the top cover 130 and the main case 120 may be further provided for ensuring tightness between the top cover 130 and the main case 120.

In order to cover the explosion-proof component 200, a protective patch 800 may be further disposed, where the protective patch 800 covers the surface of the explosion-proof component 200, so as to cover, hide and protect the explosion-proof component 200.

The preparation and testing of the battery is briefly described below.

1. Preparation of a Battery

1. Preparation of positive electrode plate

The positive electrode sheet comprises a positive electrode current collector and a positive electrode active material layer coated on the surface of the current collector. The positive electrode current collector adopts a metal foil, such as aluminum foil. The positive electrode active material layer includes a positive electrode active material, a binder, and a conductive agent. The positive electrode active material may be a composite oxide of transition metals such as lithium cobaltate, lithium iron phosphate, nickel cobalt manganese or nickel cobalt aluminum, lithium manganate, etc. The conductive agent can be carbon black, carbon nanotube, carbon fiber, graphene, conductive graphite and other conductive materials. The binder may be polytetrafluoroethylene or poly (vinylidene fluoride). The solvent may be N-methylpyrrolidone (NMP).

The following examples are not limited to the above-mentioned mixing ratio.

97% of lithium iron phosphate is prepared: 1.8% of conductive carbon black: 1.2% of a binder polyvinylidene fluoride positive electrode slurry. And mixing lithium cobaltate and a conductive agent uniformly, adding a solvent NMP for uniform dispersion, and adding a binder for viscosity adjustment to prepare the anode slurry. And uniformly coating the positive electrode slurry on the surface of a current collector, drying at high temperature to remove the solvent, and rolling to form a certain compacted positive electrode plate.

2. Preparation of negative electrode plate

The negative electrode sheet comprises a negative electrode current collector and a negative electrode active material layer coated on the surface of the current collector. The negative electrode current collector is a metal foil, such as copper foil. The anode active material layer includes an anode active material, a binder, and a conductive agent. The positive electrode active material may be graphite or a carbon-containing composite or a metal-organic material such as artificial graphite, natural graphite, mesophase carbon microspheres, carbon fibers, hard carbon, silicon carbon negative electrode, lithium negative electrode, or the like. The conductive agent can be carbon black, carbon nanotube, carbon fiber, graphene, conductive graphite and other conductive materials. Styrene-butadiene rubber or poly (vinylidene fluoride) may be used as the binder. If necessary, a thickener such as sodium carboxymethylcellulose (CMC) is added to make the cathode slurry more stable, and the solvent can be N-methyl pyrrolidone (NMP) or deionized water.

The following examples are not limited to the above-mentioned mixing ratio.

The solvent is deionized water, and 96.5% of artificial graphite is prepared: 1% of conductive carbon black: 1.5% of styrene-butadiene rubber: 1% CMC. And (3) uniformly mixing graphite and conductive carbon black, adding deionized water serving as a solvent and CMC for uniform dispersion, and adding styrene-butadiene rubber serving as a binder for viscosity adjustment to prepare the negative electrode slurry. The negative electrode slurry is uniformly coated on the surface of a current collector, then the solvent is removed by drying at high temperature, and a certain compacted negative electrode plate is formed by rolling.

3. Preparation of electrolyte

The electrolyte includes an electrolyte salt and an organic solvent, and in addition, a gel electrolyte may be used.

Examples of the organic solvent used for the electrolyte include diethyl carbonate, dimethyl carbonate, methylethyl carbonate, dipropyl carbonate, ethylene-propylene carbonate, ethylene carbonate, propylene carbonate, ethyl propionate, propyl propionate, propylene sulfite, and the like. The electrolyte salt is, for example, liPF6, liBF4, or the like.

The electrolyte solvent ratio adopted in this example was 50% propyl propionate, 25% ethylene carbonate, 16% propylene carbonate, 6% ethanedinitrile, 3% ethylene carbonate, and LiPF6 lithium salt concentration of 1.1mol/L.

4. Diaphragm

A porous polyethylene film having a thickness of 10 μm and a porosity of 30% was used.

5. Battery preparation

The positive and negative plates are cut, the negative electrode is 2mm wider than the positive plate, a negative electrode lug is led out at the position of a negative plate empty current collector, a positive electrode lug is led out at the position of a positive plate empty current collector, the width of an isolating film is 2.5mm wider than that of the negative electrode, isolation films are ensured to be insulated between the positive electrode and the negative electrode, the positive electrode active material layer is ensured to be wrapped by the negative electrode active material layer, the diaphragm is beyond the two ends of the negative electrode, and the positive electrode plate and the diaphragm are wound to obtain the battery cell 300.

As shown in fig. 1, the battery 300 is placed in the main case 120, the top cover 130 is welded to the main case 120, electrolyte is injected, and the injection holes are welded to form a battery.

2. Performance test of explosion-proof piece 200

1. Explosion-proof piece 200 valve opening fluctuation sigma test

32 batteries are sampled in each group of embodiments, an JC-B015-E10 explosion-pulling instrument is adopted to pump air from the liquid injection holes of the batteries respectively, the pumping pressure is controlled to be 0.4MPa-1.1MPa until the explosion-proof piece 200 is opened, and the valve opening pressure x of the batteries in each group of embodiments is recorded ₁ 、x ₂ …x ₃₂ According to x ₁ 、x ₂ …x ₃₂ Calculate the average value x= (x) of the 32 cell opening pressures in each set of examples ₁ +x ₂ +…+x ₃₂ ) And/32, finally calculating the valve opening fluctuation of the explosion-proof piece of each group of embodiments:

in order to ensure consistency of the welding effect, the valve opening fluctuation Σ of the explosion-proof material 200 is required to be less than or equal to 0.08.

2. Welding failure tension test of the explosion-proof piece 200:

after the explosion-proof piece 200 is opened, a LY-1066A type tensile machine is used for testing the tensile force of the safety score lines of the explosion-proof piece 200 and the shell 100, a battery is clamped on a clamp of the LY-1066A type tensile machine, so that the shell 100 is relatively fixed, the explosion-proof piece 200 is pulled, the tensile force applied to the explosion-proof piece 200 is gradually increased during testing until the explosion-proof piece 200 is separated from the shell 100, and the tensile force value at the moment is recorded, namely the welding failure tensile force of the explosion-proof piece 200.

It should be appreciated that to ensure reliability of the weld, a weld failure tension of greater than 120N is required for the explosion proof member 200.

3. Test results

And (4) carrying out cutting corrosion measurement on the tested battery to obtain related penetration and fusion width, and recording as follows:

table 1 comparative table of weld bead fusion parameters and test parameters for the present application

As can be seen from Table 1, the weld 400 of the explosion proof member 200 satisfies the following conditionThe welding line 400 has a width that meets the requirement, and the welding energy is not excessively dispersed, so that the welding line 400 can be effectively connected with the casing 100 and the explosion-proof piece 200, and further the strength and the tightness of the welding line 400 are effectively ensured. />

Table 2 comparative table of weld penetration parameters and test parameters for the battery of the present application

As can be seen from Table 2, W ₂ ≤T ₁ Can effectively improve the sealing performance and the bursting performance of the battery.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. The battery is characterized by comprising a shell and an explosion-proof piece, wherein the shell is provided with a containing cavity and a pressure relief through hole, and the pressure relief through hole is communicated with the inside of the containing cavity and the outside of the containing cavity;

the explosion-proof piece is arranged in the pressure relief through hole and is welded and connected to the shell, a welding seam is arranged at the welding joint of the explosion-proof piece and the shell, the welding seam comprises a total melting width and an effective melting width, and the total melting width is W ₁ The effective melting width is W ₂ Wherein, the method comprises the steps of, wherein,

2. the battery of claim 1, wherein the total and effective widths range from: w is more than or equal to 0.3mm ₂ ≤W ₁ ≤3mm。

3. The battery of claim 2, wherein the weld further comprises a total penetration, the total penetration being T ₁ Wherein W is ₂ ≤T ₁ ≤W ₁ 。

4. The battery of claim 3, wherein the weld further comprises an effective penetration, the effective penetration being T ₂ Wherein T is more than or equal to 0.3mm ₂ ≤T ₁ ≤1.5mm。

5. The cell of any of claims 1-4, wherein the cross-sectional shape of the weld comprises a semicircle, an acute triangle, a trapezoid, a double peak shape, and a column.

6. The battery of any one of claims 1-4, wherein the explosion proof member is welded to the housing by one of laser pulse welding and laser link welding.

7. The battery of any one of claims 1-4, wherein the housing comprises a main housing and a top cover that covers and is connected to the main housing to collectively enclose the receiving cavity;

the pressure relief through hole is disposed in one of the top cover and the main housing.

8. The battery of claim 7, wherein the explosion proof member is welded to a side of the top cover facing the receiving chamber or the explosion proof member is welded to a side of the main case facing away from the receiving chamber.

9. The battery according to any one of claims 1 to 4, wherein the explosion-proof member is provided with at least one groove in a thickness direction, a bottom wall thickness of the groove is 0.03mm or more, and a bottom wall thickness of the groove is 2mm or less.

10. The battery of claim 9, wherein the explosion proof member has a hardness of greater than or equal to 20HV and the explosion proof member has a hardness of less than or equal to 35HV.

11. The battery of claim 10, wherein the explosion proof member has an elongation of greater than or equal to 20%.

12. The battery according to claim 9, wherein the pressure release through hole includes a first communication section and a second communication section that are communicated with each other, a cross-sectional area of the first communication section along an extending direction of the pressure release through hole is larger than a cross-sectional area of the second communication section along the extending direction of the pressure release through hole, and the explosion-proof member is provided in the first communication section;