Patent Description:
The present disclosure relates to a battery cell and a battery module including the same, and more particularly, to a battery cell with improved external emission of gas generated inside the battery cell, and a battery module including the same.

As technology development and demand for mobile devices increase, the demand for secondary batteries as an energy source is rapidly increasing. In particular, secondary batteries are of great interest as energy sources not only for mobile devices such as mobile phones, digital cameras, notebooks and wearable devices, but also for power devices such as electric bicycles, electric vehicles and hybrid electric vehicles.

Depending on the shape of a battery case, these secondary batteries are classified into a cylindrical battery and a prismatic battery in which a battery assembly is included in a cylindrical or prismatic metal can, and a pouch-type battery in which the battery assembly is included in a pouch-type case of an aluminum laminate sheet. Here, the battery assembly included in the battery case is a power element including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, and capable of charging and discharging, and is classified into a jelly-roll type in which long sheet-type positive and negative electrodes coated with an active material are wound with a separator being interposed therebetween, and a stack type in which a plurality of positive and negative electrodes are sequentially stacked with a separator being interposed therebetween.

Among them, in particular, a pouch-type battery in which a stack-type or stack/folding-type battery assembly is included in a pouch-type battery case made of an aluminum laminate sheet is being used more and more due to low manufacturing cost, small weight, and easy deformation.

<FIG> is a top view showing a conventional battery cell. <FIG> is a cross-sectional view, taken along the axis a-a' of <FIG>. Referring to <FIG>, a conventional battery cell <NUM> includes a battery case <NUM> having an accommodation portion <NUM> in which a battery assembly <NUM> is mounted, and a sealing portion <NUM> formed by sealing an outer periphery thereof by heat fusion. Here, the battery cell <NUM> includes an electrode lead <NUM> protruding out of the battery case <NUM> via the sealing portion <NUM>, and a lead film <NUM> is positioned between upper and lower portions of the electrode lead <NUM> and the sealing portion <NUM>.

However, as the energy density of the battery cell increases in recent years, there is a problem that the amount of gas generated inside the battery cell also increases. In the case of the conventional battery cell <NUM>, a component capable of discharging the gas generated inside the battery cell is not included, so a venting may occur in the battery cell due to gas generation. In addition, moisture may penetrate into the battery cell damaged by the venting, which may cause side reactions, and there is a problem that battery performance deteriorates and additional gas is generated. Accordingly, there is an increasing need to develop a battery cell with improved external emission of gas generated inside the battery cell.

In other realizations <CIT> concerns a battery cell with a gas discharge pipe embedded in a lead film away from an electrode lead, <CIT> concerns a battery cell with gas discharge portion comprising slits in lead films corresponding to a slit in an electrode lead and <CIT> concerns a battery cell with gas discharge portion opened towards the exterior or the case of the battery cell.

The present disclosure is designed to solve the problems of the related art, and therefore the present disclosure is directed to providing a battery cell with improved external emission of gas generated inside the battery cell, and a battery module including the same.

The object to be solved by the present disclosure is not limited to the above-mentioned object, and the objects not mentioned here may be clearly understood by those skilled in the art from this specification and the accompanying drawings.

In one aspect of the present disclosure, there is provided a battery cell, comprising: a battery case having an accommodation portion in which a battery assembly is mounted, and a sealing portion formed by sealing an outer periphery thereof by heat fusion; an electrode lead electrically connected to an electrode tab included in the battery assembly and protruding out of the battery case via the sealing portion; and a lead film positioned at a portion corresponding to the sealing portion in at least one of an upper portion and a lower portion of the electrode lead, wherein the lead film includes a gas discharge portion formed to extend from the inside of the battery case to the outside of the battery case, and the gas discharge portion is opened toward the inside of the battery case.

A front surface and both side surfaces of the gas discharge portion based on a protruding direction of the electrode lead are closed.

The battery cell may further comprise an inner layer configured to cover at least a part of a surface of the gas discharge portion.

A material of the inner layer may have a higher melting point compared to a material of the lead film and may not react with an electrolytic solution.

The lead film may comprise a polyolefin-based material, and the inner layer may contain at least one of polyolefin-based, fluorine-based and porous ceramic-based materials.

The lead film may have a greater width than the electrode lead.

The lead film may have a greater length than the sealing portion and have a smaller length than the electrode lead.

The gas discharge portion may have a greater width than the electrode lead.

The lead film may include a first lead film and a second lead film, the first lead film may be positioned at an upper portion of the electrode lead, and the second lead film may be positioned at a lower portion of the electrode lead.

The electrode lead may be positioned between the first lead film and the second lead film, and the first lead film and the second lead film may be connected to each other.

An end of the gas discharge portion formed within the lead film may be positioned outer than an outer surface of the battery case.

An end of the gas discharge portion opened toward the inside of the battery case may be positioned inner than an inner surface of the battery case.

In another aspect of the present disclosure, there is also provided a battery module, comprising the battery cell described above.

According to the embodiments, since the present disclosure provides a battery cell including an electrode lead to which a lead film having a maximum penetration area is attached, and a battery module including the same, it is possible to improve the external emission of gas generated inside the battery cell.

The effect of the present disclosure is not limited to the above effects, and the effects not mentioned here will be clearly understood by those skilled in the art from this specification and the accompanying drawings.

Hereinafter, with reference to the accompanying drawings, various embodiments of the present disclosure will be described in detail so as to be easily implemented by those skilled in the art. The present disclosure may be implemented in various different forms and is not limited to the embodiments described herein.

In order to clearly explain the present disclosure, parts irrelevant to the description are omitted, and identical or similar components are endowed with the same reference signs throughout the specification.

In addition, since the size and thickness of each component shown in the drawings are arbitrarily expressed for convenience of description, the present disclosure is not necessarily limited to the drawings. In order to clearly express various layers and regions in the drawings, the thicknesses are enlarged. Also, in the drawings, for convenience of explanation, the thickness of some layers and regions is exaggerated.

In addition, throughout the specification, when a part "includes" a certain component, it means that other components may be further included, rather than excluding other components, unless otherwise stated.

In addition, throughout the specification, when referring to "top view", it means that the target part is viewed from above, and when referring to "cross-sectional view", it means that a vertically-cut section of the target part is viewed from a side.

Hereinafter, a pouch battery cell <NUM> according to an embodiment of the present disclosure will be described. However, here, the description will be made based on one side surface of both side surfaces of the pouch battery cell <NUM>, but it is not necessarily limited thereto, and the same or similar contents may be described in the case of the other side surface.

<FIG> is a top view showing a battery cell according to this embodiment.

Referring to <FIG>, the battery cell <NUM> according to this embodiment includes a battery case <NUM>, an electrode lead <NUM>, and a lead film <NUM>.

The battery case <NUM> includes an accommodation portion <NUM> in which a battery assembly <NUM> is mounted, and a sealing portion <NUM> formed by sealing an outer periphery thereof by heat fusion. The battery case <NUM> may be a laminate sheet including a resin layer and a metal layer. More specifically, the battery case <NUM> may be made of a laminate sheet, and may include an outer resin layer forming the outermost layer, a barrier metal layer preventing penetration of materials, and an inner resin layer for sealing.

Also, the battery assembly <NUM> may have a structure of a jelly-roll type (winding type), a stack type (lamination type), or a composite type (stack/folding type). More specifically, the battery assembly <NUM> may include a positive electrode, a negative electrode, and a separator disposed therebetween.

Hereinafter, the electrode lead <NUM> and the lead film <NUM> will be mainly described.

<FIG> is a perspective view showing an electrode lead included in the battery cell of <FIG>.

Referring to <FIG>, the electrode lead <NUM> is electrically connected to an electrode tab (not shown) included in the battery assembly <NUM>, and protrudes out of the battery case <NUM> via the sealing portion <NUM>. In addition, the lead film <NUM> is positioned at a portion corresponding to the sealing portion <NUM> in at least one of an upper portion and a lower portion of the electrode lead <NUM>. Accordingly, the lead film <NUM> may improve the sealing properties of the sealing portion <NUM> and the electrode lead <NUM> while preventing a short circuit from occurring in the electrode lead <NUM> during thermal fusion.

In addition, the lead film <NUM> may have a greater width than the electrode lead <NUM>. The lead film may have a greater length than the sealing portion and have a smaller length than the electrode lead. Accordingly, the lead film <NUM> may prevent the side surface of the electrode lead <NUM> from being exposed to the outside without interfering with the electrical connection of the electrode lead <NUM>.

In addition, the lead film <NUM> may include a first lead film and a second lead film, the first lead film may be positioned at an upper portion of the electrode lead <NUM>, and the second lead film may be positioned at a lower portion of the electrode lead <NUM>. At this time, the electrode lead <NUM> may be heat-fused together with the sealing portion <NUM> in a state of being located between the first lead film and the second lead film, so that the first lead film and the second lead film may be connected to each other.

Accordingly, the lead film <NUM> may prevent the side surface of the electrode lead <NUM> from being exposed to the outside, while improving the sealing properties of the sealing portion <NUM> and the electrode lead <NUM>.

<FIG> is a cross-sectional view, taken along the axis c-c' of <FIG>. <FIG> is a cross-sectional view, taken along the axis d-d' of <FIG>. <FIG> is a cross-sectional view, taken along the axis b-b' of <FIG>.

Referring to <FIG>, the lead film <NUM> includes a gas discharge portion <NUM> formed to extend from the inside of the battery case <NUM> to the outside of the battery case <NUM>, and the gas discharge portion <NUM> is opened toward the inside of the battery case <NUM>. In addition, a front surface and both side surfaces of the gas discharge portion <NUM> based on a protruding direction of the electrode lead <NUM> are closed. Here, the gas discharge portion <NUM> may refer to a portion in which the remaining surfaces of the lead film <NUM> other than for the surface opened toward the inside of the battery case <NUM> are not adhered with each other. In addition, the gas discharge portion <NUM> may have a greater width than the electrode lead <NUM>.

Accordingly, the gas generated inside the battery case <NUM> flows in the gas discharge portion <NUM> of the lead film <NUM>. In addition, when the pressure of the lead film <NUM> is higher than a predetermined pressure, the gas generated inside the battery case <NUM> passes through the gas discharge portion <NUM> to be discharged to the outside. In addition, since a gas permeation area is maximized by the gas discharge portion <NUM>, the lead film <NUM> discharges a large amount of gas.

In addition, the lead film <NUM> may further include an inner layer <NUM> that covers at least a part of the surface of the gas discharge portion <NUM>. More preferably, the inner layer <NUM> may cover the entire surface of the gas discharge portion <NUM>. Here, the inner layer <NUM> may be coated on the gas discharge portion <NUM> or may be manufactured as a separate film and attached to the gas discharge portion <NUM>.

Accordingly, even if the lead film <NUM> is heat-fused together with the sealing portion <NUM> in a state of being located in at least one of the upper portion and the lower portion of the electrode lead <NUM>, the gas discharge portion <NUM> may be preserved without being heat-fused by the inner layer <NUM>.

More specifically, the inner layer <NUM> may be made of a material having a higher melting point compared to the material of the lead film <NUM>. In addition, the inner layer <NUM> may be made of a material that does not react with an electrolytic solution contained in the battery case <NUM>. For example, the lead film <NUM> may include a polyolefin-based material, and the inner layer <NUM> may include at least one of a polyolefin-based material, a fluorine-based material, and a porous ceramic-based material. In addition, the inner layer <NUM> may include a getter material to increase gas permeability while minimizing water permeability. As an example, the getter material may be calcium oxide (CaO), barium oxide (BaO), lithium chloride (LiCl), silica (SiO<NUM>), or the like, but is not limited thereto, and any material reacting with water (H<NUM>O) may be used.

Accordingly, since the inner layer <NUM> is made of the above-described material, the inner layer <NUM> does not react separately with the electrolytic solution and does not cause heat fusion, thermal deformation, or the like during the high-temperature thermal fusion process, so that the gas discharge portion <NUM> may be kept blank. That is, the inner surface of the gas discharge portion <NUM> may be maintained in a non-adhesive state. In addition, when the gas generated in the battery case <NUM> flows into the gas discharge portion <NUM>, the inner surfaces of the gas discharge portion <NUM> may be spaced apart from each other, so that the gas introduced into the gas discharge portion <NUM> may be easily discharged to the outside. In addition, since the lead film <NUM> is made of the above-described material, the lead film <NUM> may maintain the airtightness of the battery cell <NUM> and also prevent leakage of the internal electrolytic solution.

Referring to <FIG>, an end of the gas discharge portion <NUM> formed within the lead film <NUM> may be positioned outer than the outer surface of the battery case <NUM>. In addition, an end of the gas discharge portion <NUM> that is opened toward the inside of the battery case <NUM> may be positioned inner than the inner surface of the battery case <NUM>.

Accordingly, the lead film <NUM> may maximize the area of the gas discharge portion <NUM>, thereby maximizing the area of the inner layer <NUM> to which the gas generated inside the battery case <NUM> is exposed. In addition, the permeation area of the gas generated inside the battery case <NUM> may be maximized, so that a large amount of gas may be discharged.

<FIG> is a diagram showing the flow of gas generated inside the battery cell of <FIG> and discharged to the outside.

Referring to <FIG>, the gas generated inside the battery cell <NUM> of <FIG> may flow toward the gas discharge portion <NUM> of the lead film <NUM>. At this time, the gas discharge portion <NUM> may be expanded upward and downward compared to <FIG> by the gas inside the battery cell <NUM>. Also, as indicated by A in <FIG>, when the gas inside the battery cell <NUM> exceeds a predetermined pressure, the gas inside the battery cell <NUM> may be discharged to the outside through the gas discharge portion <NUM>.

Accordingly, as compared with <FIG>, as the gas discharge portion <NUM> is positioned on the lead film <NUM>, the permeation area of the gas inside the battery cell <NUM> is also maximized, and thus the amount of the gas discharged to the outside may also be maximized.

A battery module according to another embodiment of the present disclosure includes the battery cell described above. Meanwhile, one or more battery modules according to this embodiment may be packaged in a pack case to form a battery pack.

The battery module described above and the battery pack including the same may be applied to various devices. These devices may be transportation means such as electric bicycles, electric vehicles, hybrid electric vehicles, and the like, but the present disclosure is not limited thereto, and the present disclosure may be applied various devices that can use a battery module and a battery pack including the same.

Hereinafter, the content of the present disclosure will be described through more specific examples, but the following examples are for illustratively describing the present disclosure, and the scope of the present disclosure is defined by the appended claims.

A battery cell including a battery case having an accommodation portion in which a battery assembly was mounted and a sealing portion formed by sealing an outer periphery of the battery case by heat fusion was manufactured. Here, an electrode tab included in the battery assembly was electrically connected to an electrode lead, and the electrode lead protruded out of the battery case via the sealing portion. At this time, a lead film was attached to a position corresponding to the sealing portion in an upper portion of the electrode lead, and a gas discharge portion extending from the inside of the battery case to the outside of the battery case was formed in the lead film.

A battery cell was manufactured in the same manner as in the example, except that a separate gas discharge portion was not formed in the lead film.

For the battery cell of the example, CT was taken centered on the sealing portion where the lead film and the electrode lead were located, and a CT image of the corresponding portion was obtained as shown in <FIG>.

<FIG> is a diagram showing a cross section of a battery cell according to Experimental Example <NUM>. In the battery cell of the example, <FIG> is a CT image of a cross-section of the lead film and electrode lead before the internal pressure of the battery cell of the example is increased, and <FIG> is a CT image of a cross-section of the lead film and electrode lead after the internal pressure of the battery cell of the example increases by injecting gas into the battery cell of the example.

Referring to <FIG>, it is confirmed that, before the internal pressure of the battery cell of the example increases, there is no significant change centered on the gas discharge portion formed on the lead film. However, as the internal pressure of the battery cell of the example increases, it may be seen that the gas discharge portion formed in the lead film is spaced apart in the vertical direction (arrow direction), as shown in <FIG>.

Accordingly, as in this example, if the gas discharge portion is formed in the lead film of the battery cell, the gas discharge portion is vertically spaced apart when the internal pressure of the battery cell increases, so that the gas inside the battery cell may be introduced into the gas discharge portion. That is, it may be seen that the gas discharge portion included in the battery cell of this example serves as a gas discharge path of the battery cell.

For the battery cells of the example and the comparative example, the gas pressure inside the battery cell over time was measured, and the results are shown in <FIG>. In the battery cell of the example, the initial internal pressure of the battery cell was <NUM> atm.

<FIG> is a diagram showing a measurement result of a gas pressure in a battery cell according to Experimental Example <NUM>.

Referring to <FIG>, it may be confirmed that, in the battery cell according to the comparative example, the internal pressure decreases relatively little as time elapses in a state where the initial internal pressure is <NUM> atm. On the contrary, in the battery cell according to the example, it may be seen that the internal pressure is relatively significantly decreased as time elapses in a state where the initial internal pressure is <NUM> atm. That is, in the battery cell according to the example, it may be confirmed that the internal gas is effectively discharged to the outside through the gas discharge portion formed in the lead film over time.

Claim 1:
A battery cell (<NUM>), comprising:
a battery case (<NUM>) having an accommodation portion (<NUM>) in which a battery assembly (<NUM>) is mounted, and a sealing portion (<NUM>) formed by sealing an outer periphery thereof by heat fusion;
an electrode lead (<NUM>) electrically connected to an electrode tab included in the battery assembly and protruding out of the battery case via the sealing portion (<NUM>); and
a lead film (<NUM>) positioned at a portion corresponding to the sealing portion (<NUM>) in at least one of an upper portion and a lower portion of the electrode lead (<NUM>),
characterised in that the lead film (<NUM>) discharges gas and includes a gas discharge portion (<NUM>) formed to extend from the inside of the battery case to the outside of the battery case, wherein the gas discharge portion (<NUM>) maximizes a gas permeation area and
the gas discharge portion (<NUM>) is opened toward the inside of the battery case and is closed on a front surface and on both side surfaces based on a protruding direction of the electrode lead (<NUM>), wherein gas generated inside the battery cell exceeding a predetermined pressure flows inside the gas discharge portion and is discharged to the outside through the gas discharge portion (<NUM>).