KR20180039986A - Battery pack - Google Patents

Abstract

The present invention provides a battery pack capable of instantaneously detecting venting gas generated in a secondary battery inside a battery pack when the battery leaks to the outside of the battery pack. The battery pack according to the present invention is a battery pack having a battery module housed in a pack cover. The battery pack includes a venting part for discharging venting gas from a secondary battery included in the battery module to the outside of the battery pack, A venting valve coupled to the venting part from the outside of the pack cover and an identification part including a pointing material whose color changes in response to the venting gas, .

Description

Battery pack

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a battery pack, and more particularly, to a battery pack that can easily detect whether gas is generated in a secondary battery included in the battery pack.

The secondary rechargeable batteries are nickel-cadmium batteries, nickel-hydrogen batteries, nickel-zinc batteries, and lithium secondary batteries. Among them, lithium secondary batteries have almost no memory effect compared to nickel- It is very popular because of its low self-discharge rate and high energy density.

These lithium secondary batteries mainly use a lithium-based oxide and a carbonaceous material as a cathode active material and an anode active material, respectively. The lithium secondary battery includes an electrode assembly in which a positive electrode plate and a negative electrode plate each coated with such a positive electrode active material and a negative electrode active material are disposed with a separator interposed therebetween, and an outer casing, that is, a battery case, for sealingly storing the electrode assembly together with the electrolyte solution.

Generally, a lithium secondary battery can be classified into a can type secondary battery in which an electrode assembly is embedded in a metal can, and a pouch type secondary battery in which an electrode assembly is embedded in a pouch of an aluminum laminate sheet, depending on the shape of the casing.

In recent years, secondary batteries are widely used not only in small-sized devices such as portable electronic devices, but also in medium to large-sized devices such as automobiles and electric power storage devices. When used in such a medium to large-sized apparatus, a large number of secondary batteries are electrically connected to increase capacity and output. In particular, pouch-type secondary batteries are widely used because they are easy to laminate in such a middle- or large-sized apparatus.

However, since the pouch-type secondary battery is generally packaged in a battery case of a laminate sheet of aluminum and polymer resin, the mechanical rigidity is not so large. Therefore, when constructing a battery module including a plurality of pouch type secondary cells, a frame is often used to protect the secondary battery from external impact, prevent the flow of the secondary battery, and facilitate stacking. Etc. to assemble the battery pack.

The pouch-type secondary battery can generate gas from the inside at any time while repeating charging and discharging, and this is called venting gas. However, the venting gas may contain a harmful component to the human body, and when the venting gas is exhausted, the user of the battery pack may inhale the venting gas. In particular, in the case of a hybrid vehicle or an electric vehicle, since a middle- or large-sized battery pack including a large number of secondary batteries is mounted, venting gas is likely to be generated from the secondary battery. Therefore, venting gas is discharged from the battery pack, , There is a risk that the driver of the vehicle suffers harm to the human body by sucking the harmful gas, and the driving ability is reduced due to the harmful gas during driving, thereby causing accidents.

Therefore, management of the venting gas is very important. However, when the venting gas is discharged from the secondary battery inside the battery pack, the existing battery packs can not immediately recognize the discharge situation, and there is a limit to detect the gas concentration. The battery pack without the gas concentration sensor can not know whether the venting gas is discharged from the secondary battery until the battery pack is disassembled.

In the long term, it is possible to check whether there is an abnormality such as a venting gas through the deterioration of the function of the battery pack. However, this method raises the risk of the battery pack user. Therefore, there is a need for a structure that can easily detect the venting gas emission immediately.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a battery pack which can be instantaneously detected when venting gas generated in a secondary battery inside a battery pack leaks to the outside of the battery pack do.

Other objects and advantages of the present invention will become apparent from the following description, and it will be understood by those skilled in the art that the present invention is not limited thereto. It will also be readily apparent that the objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.

According to an aspect of the present invention, there is provided a battery pack including a battery pack housed in a pack cover, the battery pack comprising: A venting part is included in the pack cover, a venting valve is coupled to the venting part from the outside of the pack cover, and an identification part including a pointing material whose color changes in response to the venting gas, And is installed around the venting portion on the gas moving path.

According to an aspect of the present invention, the identification unit includes a membrane for sealing the ventilation part from the inside of the pack cover so that the gas inside the battery pack is discharged through the venting part and the moisture inside the battery pack is not discharged, Is coated with the indicator material.

According to another aspect of the present invention, the identification unit may include a pH test paper adhered to the inside of the pack cover, a window provided on the pack cover so that the color of the pH test paper can be confirmed from outside the pack cover, .

At this time, the window may be provided above the venting part. The transparent member may be formed by insert injection inside the pack cover. The pH test paper may be attached to the inside of the pack cover with an adhesive material while covering the transparent member.

According to the present invention, when the venting gas generated in the secondary battery inside the battery pack is discharged to the outside of the battery pack, it can be visually recognized. It is possible to know whether or not the venting gas is discharged by paying attention to the fact that the main component of the venting gas discharged from the secondary battery is acidic.

According to an aspect of the present invention, when the venting gas leaks, the gas molecules escape to the venting valve through the membrane and the venting portion due to an increase in internal pressure. Since the indicator material is applied to the membrane located on the gas transfer path, the membrane can be sensitively changed in color. By removing the venting valve, the color change of the membrane inside the venting part can be checked immediately, so it can easily check whether the venting gas is exhausted.

Accordingly, it is possible to easily grasp the abnormality related to whether or not the ventilation gas of the battery pack is discharged during the maintenance.

According to another aspect of the present invention, a pH test paper which is easy to identify can be attached to the inside of the battery pack, and can be visually confirmed from the outside of the pack cover through the window, so that the state of the inside of the battery pack can be more easily confirmed. There is no stiffness problem because it implements structure where mechanical strength is sufficient.

Therefore, according to these aspects of the present invention, even if venting gas is generated from the secondary battery, it is possible to immediately and easily detect whether the venting gas generated from the secondary battery is discharged to the outside of the battery pack.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate preferred embodiments of the invention and, together with the description of the invention given below, serve to further the understanding of the technical idea of the invention. And should not be construed as limiting.
1 is a perspective view of a lower pack cover including a venting part as a lower pack cover included in a battery pack according to an embodiment of the present invention.
2 is a perspective view showing a state in which the battery module is seated on the lower pack cover of FIG. 1;
FIG. 3 is a perspective view showing a state in which the upper pack cover is assembled by being joined to the lower pack cover of FIG. 2. FIG.
4 is a perspective view of a battery pack manufactured by coupling a venting valve to a venting portion of the lower pack cover of FIG.
5 is a view illustrating a venting gas movement path in a battery pack according to an embodiment of the present invention.
FIG. 6 is a perspective view illustrating an identification unit viewed from the outside of the battery pack according to an embodiment of the present invention. FIG.
7 is a perspective view showing an identification unit installed in a battery pack according to an embodiment of the present invention.
8 is a top view of a lower pack cover included in a battery pack according to another embodiment of the present invention.
9 is an enlarged view of a portion A in Fig.
10 is a sectional view taken along line BB of Fig.
11 is a perspective view for explaining an identification part viewed from the outside of the battery pack according to another embodiment of the present invention.
12 to 14 are perspective views of the battery pack according to another embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms, and the inventor should appropriately interpret the concepts of the terms appropriately It should be interpreted in accordance with the meaning and concept consistent with the technical idea of the present invention based on the principle that it can be defined. Therefore, the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and do not represent all the technical ideas of the present invention. Therefore, It is to be understood that equivalents and modifications are possible.

1 is a perspective view of a lower pack cover including a venting part as a lower pack cover included in a battery pack according to an embodiment of the present invention. 2 is a perspective view showing a state in which the battery module is seated on the lower pack cover of FIG. 1; FIG. 3 is a perspective view showing a state in which the upper pack cover is assembled by being joined to the lower pack cover of FIG. 2. FIG. 4 is a perspective view of a battery pack manufactured by coupling a venting valve to a venting portion of the lower pack cover of FIG.

Referring first to FIG. 1, the lower pack cover 10 is a substantially box-shaped case having a space for accommodating therein a battery module. That is, the lower pack cover 10 includes a substantially rectangular bottom surface 11 and front, rear, left and right side walls 12a to 12d standing up from four sides of the bottom surface 11 . The lower pack cover 10 is provided with a venting portion 15 for discharging the venting gas from the secondary battery included in the battery module to the outside of the battery pack. The venting part (15) is formed on one of the side walls of the lower pack cover (10). For example, the venting portion 15 is formed on the front side wall 12a of the lower pack cover 10.

When the battery pack is manufactured, the battery module 20 is seated in the bottom pack cover 10, such as the bottom surface 11, as shown in FIG.

Next, referring to FIG. 3, the upper pack cover 30 is assembled by engaging the upper pack cover 10 on the lower pack cover 10. The upper pack cover 30 is a substantially lid-viewable case that covers the battery module 20 and can be cut off from the outside. That is, the upper pack cover 30 also includes a substantially rectangular bottom surface 31 and front, rear, left, and right side walls 32a-32d that extend downward from the four sides of the bottom surface 31 . The lower pack cover 10 and the upper pack cover 30 are brought into contact with each other by the side walls 12a to 12d and 32a to 32d being brought into contact with each other through the fastening means such as the bolt 35. [

Finally, referring to FIG. 4, the venting valve 40 is coupled to the venting part 15 to complete the battery pack 50. The venting valve 40 may be coupled to the venting part 15 in advance before the upper pack cover 30 is joined on the lower pack cover 10. [

The battery pack 20 is assembled by housing the battery pack 20 in a pack cover (in this embodiment, the lower pack cover 10 and the upper pack cover 30) (Lower pack cover 10 in this embodiment) for venting the venting gas from the secondary battery included in the battery pack 50 to the outside of the battery pack 50, The venting valve 40 is coupled to the venting portion 15 from the outside of the lower pack cover 10).

FIG. 5 is a view illustrating a venting gas moving path in a battery pack according to an embodiment of the present invention. For convenience, the upper pack cover 30 is omitted.

A secondary battery included in the battery module 20, for example, a pouch-type secondary battery, can generate venting gas from the inside during use at any time while repeating charge and discharge. As shown by a dotted line arrow in FIG. 5, And moves along the side walls 12a to 12d of the lower pack cover 10 in the battery pack 50 to be discharged to the outside of the battery pack 50 through the venting part 15. [ The venting valve 40 connected to the venting part 15 normally closes the venting part 15 and is opened when the venting gas leaks from the secondary battery and the internal pressure of the battery pack 50 rises above the maximum reference value, And venting gas is discharged out of the pack 50. In the case of a battery pack for an automobile, the discharged venting gas may be subjected to a predetermined treatment so as not to directly affect a driver of a vehicle, such as being exhausted through a separate purification device.

FIG. 6 is a perspective view illustrating an identification unit viewed from the outside of the battery pack according to an embodiment of the present invention. FIG. 7 is a perspective view showing an identification unit installed in a battery pack according to an embodiment of the present invention.

Referring to Figs. 6 and 7, the battery pack 50 includes an identification unit 60 including an indicating material whose color changes in response to the venting gas. The identification portion 60 is installed around the venting portion 15 on the venting gas moving path inside the pack cover described with reference to Fig. In particular, in this embodiment, the identification portion 60 is the membrane 62 to which the indicating substance is applied. The gas is discharged from the inside of the battery pack 50 through the venting part 15 and the ventilation part 15 is moved from the inside to the outside of the battery pack 50 In the embodiment, it is blocked from the inside of the lower pack cover 10. Particularly, in this embodiment, the membrane 62 is formed at a position corresponding to the position of the venting part 15 inside the front side wall 12a of the lower pack cover 10. It can be said to be semi-permeable because it is permeable to gas but impermeable to moisture. The material may be poly (carbonyl-ethylene). The color may be transparent or white. PCE20-108 available from Schreiner, a commercially available semipermeable film, can be used. In the case of a battery pack for an automobile, the moisture of the battery pack may be seriously damaged when the moisture is discharged to the parts of the vehicle, so moisture management is required. The membrane 62 prevents the moisture of the battery pack 50 from being discharged to the outside, thereby preventing damage to vehicle parts. The indicator 62 is coated with an indicator material that changes color by reaction with the venting gas and is included as an identification unit 60. The application method may be spraying, printing, printing, brushing, dropping, and the like.

The main component of the venting gas discharged from the secondary battery is acidic. Therefore, it is preferable that the indicating substance is a substance which is discolored in response to the acidity (pH concentration). For example, the indicator material is litmus. This can be applied to the membrane 62 in the form of a solution. Litmus is a bluish purple pigment obtained from various lichens, especially Roccella tinctoria. It is used as an indicator in the range of pH 4.5 ~ 8.3 because it is red by acid and blue by alkali. It is contained in gypsum powder, solidified, solidified and put on the market. Water, alcohol and so on. The litmus solution was prepared by grinding 100 g of litmus granules, dissolving in 200 mL of 40% ethanol, boiling for 1 to 2 minutes, centrifuging the supernatant to make 400 mL after adding 40% ethanol and dropping 1N HCl until the solution became purple Lt; / RTI > The litmus solution may be applied to the membrane 62 by spraying and used as the identification portion 60.

In this embodiment, when the venting gas leaks, the gas molecules escape to the venting valve 40 through the membrane 62 and the venting part 15 due to an increase in internal pressure of the battery pack 50. Since the venting gas of the secondary battery inside the battery pack 50 necessarily reaches the membrane 62, the venting gas reacts with the indicating material to discolor the membrane 62 . In the case of a lithium ion secondary battery, an electrolyte solution formed by adding a lithium salt and various functional additives to a non-aqueous organic solvent such as ethylene carbonate or propylene carbonate is generally used. There is a fluorine component in the lithium salt material or the impurity. In the electrolyte of the used secondary battery, fluorine usually forms the coating of the active material layer or exists in the lithium fluoride form, but it is also present in a small amount of the fluoric acid form. The venting gas may include such hydrofluoric acid, and in such a case can be recognized by the discoloration of the membrane 62. Particularly, when the venting gas leaks and the electrolytic solution also leaks, electrolytic salts such as LiPF 6 and LiBF are decomposed by moisture contact inside the battery pack 50, and when the concentration of hydrofluoric acid increases, the pH value is lower than 7, It can be acidic to about 5. Thus, the indicator material, such as litmus, applied to the membrane 62 may exhibit a red color that is indicative of acid, and the membrane 62, which may be transparent or white, may be sensitively hued.

When the venting valve 40 is pulled out, the color of the membrane 62 provided inside the venting part 15 can be confirmed from the outside of the battery pack 50. For example, if it was initially transparent but changed to red, the color change would be detected immediately and it would be easy to see if venting gas was emitted. Therefore, even if the gas concentration sensor is not provided, it is possible to easily determine whether or not the venting gas is discharged through the separation of the venting valve 40 only by the color change of the membrane 62, without disassembling the battery pack 50. Accordingly, it is possible to easily grasp the abnormality related to whether or not the venting gas is discharged from the battery pack 50 through the minimum operation of extracting the venting valve 40 at the time of maintenance.

Hereinafter, a battery pack according to another embodiment of the present invention will be described.

8 is a top view of a lower pack cover included in a battery pack according to another embodiment of the present invention. 9 is an enlarged view of a portion A in Fig. 10 is a sectional view taken along the line B-B in Fig. 11 is a perspective view for explaining an identification part viewed from the outside of the battery pack according to another embodiment of the present invention.

8 to 11, the battery pack 50 'has the same structure as that of the battery pack 50 of the previous embodiment except that the pack cover (in this embodiment, the lower pack cover 10' and the upper pack cover 30) And a venting part 15 for discharging the venting gas from the secondary battery included in the battery module to the outside of the battery pack 50 ' (Not shown in FIG. 4) is mounted on the venting portion 15 outside the pack cover (the lower pack cover 10 'in this embodiment) Is the same as 40 of Fig. The venting portion 15 is provided with a membrane 62. The gas in the battery pack 50 'is discharged through the venting portion 15 of the membrane 62 and the venting portion 15 is inserted into the battery pack 50' so that moisture in the battery pack 50 ' Block from the inside. The membrane 62 may or may not be coated with the same indicator material as in the previous embodiment.

The lower pack cover 10 'is different only in the lower pack cover 10 and the identifying portion 60' as described above. The lower pack cover 10 ' The movement path is also the same as the battery pack 50.

The battery pack 50 'is provided with a window 64 on the front side wall 12a of the lower pack cover 10' above the venting part 15. The window 64 may be provided in the form of a hole through the lower pack cover 10 '. The window 64 is covered with a transparent member 66. The inside can be seen from the outside of the battery pack 50 'through the transparent member 66.

12 to 14 are perspective views of the battery pack according to another embodiment of the present invention.

Referring to FIG. 12, a window 64 is shown in the form of a hole through the lower pack cover 10 '. Referring to Fig. 13, the transparent member 66 covers the window 64. Fig. The transparent member 66 may be formed by insert injection inside the lower pack cover 10 '. The material can be, for example, acrylic. By forming the transparent member 66 inside the lower pack cover 10 'instead of forming the transparent member 66 on the outer side of the lower pack cover 10' Can be prevented from falling off from the cover 10 ', and there is a mechanically robust advantage. Referring to FIG. 14, a pH test paper 68 is attached to the inside of the lower pack cover 10 'on the transparent member 66. the pH test paper 68 is attached at a position corresponding to the position of the window 64. [ the pH test paper 68 may be adhered with an adhesive material inside the front side wall 12a of the lower pack cover 10 'around the window 64 in a size larger than the size of the window 64. [ Thus, the window 64, the transparent member 66, and the pH test paper 68 constitute the identification portion 60 '.

As described above, in this embodiment, the identification portion 60 'is configured so that the color of the pH test paper 66 inside the battery pack 50' can be confirmed from outside the battery pack 50 'through the window 64 do. This identification part 60 'is formed on the venting part 15 in the lower pack cover 10'. Since the venting gas is discharged to the outside through the venting part 15, the venting gas must pass through the identifying part 60 '. That is, the identification portion 60 'is provided around the venting gas movement path. The identification part 60 'has a structure where the mechanical strength of the lower pack cover 10' is sufficient, so that there is no stiffness problem.

As mentioned above, the main component of the venting gas discharged from the secondary battery is acidic. Therefore, the pH test paper 68 reacts with the venting gas to change color, thereby confirming whether or not the venting gas is discharged.

The pH test paper 68 may be litmus paper. Litmus paper is made from the litmus solution mentioned above. Litmus, a weakly acidic substance, dissociates in a small proportion in aqueous solution to produce H ⁺ . However, since there is a greater amount of H ⁺ present in the acid solution than in the aqueous solution, litmus is placed in an acidic solution, and the litmus can not emit H ⁺ but exists in a structure with H attached. The color of the material changes according to the structure. The litmus of the structure with H is mainly absorbed the light of the green wavelength band, and becomes a complementary color of red. Therefore, when litmus paper is put into acid solution, most of litmus that is attached to paper is red because it exists in the form of H. Generally, in order to clearly understand the change of color, a blue litmus paper in which H is dissociated when testing an acidic solution, and a red litmus paper in which H is adhered when a basic solution is tested, . Thus, the pH test strip 68 may be a blue litmus paper.

14, the lower pack cover 10 'formed up to the identification portion 60' is prepared, and then the battery module is seated. By assembling the upper pack cover 30 in the same manner as described above, the battery pack 50 ' . For example, immediately after the battery pack 50 'is manufactured, the pH test paper 68 seen through the window 64 is blue. When the venting gas is generated during use of the battery pack 50 ', the pH test paper 68 changes to red. Color identification of the pH test paper 68 discolored through the window 64 is immediately possible without disassembling the battery pack 50 '. Since the identification portion 60 'is formed around the venting gas movement path, even a very small amount of venting gas can be sensitively sensed through the color change of the pH test paper 68.

The pH test paper 68 may be prepared by applying a litmus solution in addition to litmus paper or by impregnating or impregnating it into a polymer film or fiber. The polymer in the polymer film or the polymer fiber may be selected from the group consisting of polyvinylidene fluoride (PVdF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polypyrophyfluorene (PSf) and polyacrylonitrile (PAN) and the like.

As described above, the pH test paper 68, which is easy to identify, is attached to the inside of the battery pack 50 'and can be visually confirmed through the window 64, so that the state of the inside of the battery pack 50' I will. Therefore, even if the venting gas is generated from the secondary battery, it can be immediately detected whether the venting gas generated from the secondary battery is discharged to the outside of the battery pack 50 '. Even if a small amount of venting gas is discharged, it is possible to quickly confirm whether or not the ventilation gas can be easily visually inspected, thereby facilitating the maintenance and maintenance of the battery pack 50 '. The position of the pH test paper 68 is close to the venting portion 15, so that the venting portion 15 is one of the positions where the venting portion 15 can contact the venting gas first when the venting gas is discharged. Therefore, venting gas detection can be most easily achieved when the venting gas is exhausted.

In the above embodiments, the venting part 15 is illustrated as being formed only on the front side of the lower pack case 10, 10 ', but the venting part 15 may be formed on the lower pack case 10, 10' . For example, the venting portion 15 may be formed on the rear side in addition to the front side. In this case, the identification portions 60 and 60 'may also be formed to correspond to the respective venting portions 15. The venting part 15 may be formed in the upper pack case 30 instead of the lower pack case 10, 10 '. In this case as well, the identification portions 60 and 60 'are also formed so as to correspond to the respective venting portions 15.

The battery pack according to the present invention is provided with a venting portion through which the venting gas can be discharged so as to control the movement path of the venting gas in the battery pack and form an identification portion close to the movement path, There is a characteristic in having to check whether.

The battery pack according to the present invention can be applied to an automobile such as an electric car or a hybrid car. That is, the automobile according to the present invention may include the battery pack according to the present invention.

In the present specification, terms indicating upward, downward, leftward, rightward, forward, and backward directions are used, but these terms are for convenience of explanation only and may vary depending on the position of an object or the position of an observer It will be apparent to those skilled in the art that the present invention is not limited thereto.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not to be limited to the details thereof and that various changes and modifications will be apparent to those skilled in the art. It is to be understood that various changes and modifications may be made without departing from the scope of the appended claims. It is intended that all changes and modifications that come within the meaning and range of equivalency of the claims, as well as any equivalents thereof, be within the scope of the present invention.

10, 10 ': Lower pack cover 15: Venting part
20: battery module 30: upper pack cover
35: Bolt 40: Venting valve
50, 50 ': battery pack 60, 60': identification unit
62: membrane 64: window
66: Transparent member 68: pH test paper

Claims (6)

A battery pack having a battery module housed in a pack cover,
Wherein a venting portion for discharging venting gas from a secondary battery included in the battery module to the outside of the battery pack is included in the pack cover and a venting valve is coupled to the venting portion from the outside of the pack cover,
Wherein an identification part including a pointing material whose color changes in response to the venting gas is installed around the venting part on the venting gas moving path inside the pack cover. 2. The battery pack according to claim 1, wherein the identification unit includes a membrane for sealing the ventilation part from the inside of the pack cover so that gas inside the battery pack is discharged through the venting part and moisture in the battery pack is not discharged, Wherein the indicating material is applied. [2] The apparatus according to claim 1, wherein the identification unit comprises a pH test paper adhered to the inside of the pack cover, a window provided on the pack cover so as to enable color checking of the pH test paper from outside the pack cover, And a battery pack. The battery pack according to claim 3, wherein the window is provided on an upper portion of the venting portion. The battery pack according to claim 3, wherein the transparent member is formed by insert injection inside the pack cover. The battery pack according to claim 5, wherein the pH test paper is attached to the inside of the pack cover with an adhesive material while covering the transparent member.

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