KR20230096735A - Rechargeable battery and battery pack comprising the same - Google Patents

Abstract

The present invention relates to a secondary battery and a battery pack including the same, and the secondary battery according to the present invention includes an electrode assembly in which electrodes and separators are alternately stacked and wound; a center member positioned at a winding center of the electrode assembly; a gas absorbent accommodated inside the center member; and a battery case accommodating the electrode assembly and the center member, and when the center member is melted by heat, the gas absorber is exposed and gas inside the battery case is absorbed.

Description

Secondary battery and battery pack including the same {RECHARGEABLE BATTERY AND BATTERY PACK COMPRISING THE SAME}

The present invention relates to a secondary battery and a battery pack including the same.

Secondary batteries, unlike primary batteries, can be recharged, and have recently been extensively researched and developed due to their small size and high capacity. As technology development and demand for mobile devices increase, demand for secondary batteries as an energy source is rapidly increasing.

Secondary batteries are classified into coin cells, cylindrical cells, prismatic cells, and pouch-type cells according to the shape of a battery case. In a secondary battery, an electrode assembly installed inside a battery case is a power generating device capable of charging and discharging, consisting of a laminated structure of electrodes and separators.

The electrode assembly is a jelly-roll type in which a separator is interposed between a sheet-type positive electrode and a negative electrode coated with an active material, and a stack type in which a plurality of positive and negative electrodes are sequentially stacked with a separator interposed therebetween. , and a stack/folding type in which unit cells of a stack type are wound with a long separation film. The dual jelly roll-type electrode assembly is widely used because it is easy to manufacture and has a high energy density per weight.

However, conventional secondary batteries have a problem of exploding due to internal pressure when internal gas is rapidly generated.

Korean Patent Publication No. 10-2016-0010121

One aspect of the present invention is to provide a secondary battery capable of preventing explosion due to rapid gas generation.

A secondary battery according to an embodiment of the present invention includes an electrode assembly in which electrodes and separators are alternately stacked and wound; a center member positioned at a winding center of the electrode assembly; a gas absorbent accommodated inside the center member; and a battery case accommodating the electrode assembly and the center member, and when the center member is melted by heat, the gas absorbent is exposed and gas inside the battery case can be absorbed.

Also, a battery pack according to an embodiment of the present invention may include a secondary battery according to an embodiment of the present invention.

According to the present invention, when a secondary battery explosively generates gas at a high temperature, the center member positioned at the winding center of the electrode assembly is melted at a high temperature to expose the gas absorbent accommodated therein and absorb the gas, resulting in rapid gas generation. Explosion can be prevented.

1 is an exploded perspective view showing a secondary battery according to an embodiment of the present invention.
2 is a perspective view showing an electrode assembly and a center member in a secondary battery according to an embodiment of the present invention.
3 is a cross-sectional view showing a state before melting of a center member in a secondary battery according to an embodiment of the present invention.
4 is a cross-sectional view showing a melted state of a center member in a secondary battery according to an embodiment of the present invention.

Objects, specific advantages and novel features of the present invention will become more apparent from the following detailed description and preferred embodiments taken in conjunction with the accompanying drawings. In adding reference numerals to components of each drawing in this specification, it should be noted that the same components have the same numbers as much as possible, even if they are displayed on different drawings. In addition, the present invention may be embodied in many different forms and is not limited to the embodiments described herein. In addition, in describing the present invention, detailed descriptions of related known technologies that may unnecessarily obscure the subject matter of the present invention will be omitted.

1 is an exploded perspective view showing a secondary battery according to an embodiment of the present invention, Figure 2 is a perspective view showing an electrode assembly and a center member in a secondary battery according to an embodiment of the present invention, Figure 3 is a perspective view showing an embodiment of the present invention This is a cross-sectional view showing a state before melting of the center member in the secondary battery according to FIG.

1 to 3 , the secondary battery 100 according to the embodiment of the present invention includes an electrode assembly 110 in which electrodes 116 and separators 113 are alternately stacked and wound, and an electrode assembly 110. It includes a center member 120 positioned at the center of the winding, a gas absorbent 130 accommodated inside the center member 120, and a battery case 170 accommodating the electrode assembly 110 and the center member 120. . Meanwhile, the secondary battery 100 according to an embodiment of the present invention may further include a cap 160 covering the open accommodating space 171 of the battery case 170 .

In more detail, referring to FIG. 1 , the electrode assembly 110 is a power generating element capable of charging and discharging, and an electrode 116 and a separator 113 are assembled to form a structure in which they are alternately stacked. Here, the electrode assembly 110 may have a wound shape. In this case, the electrode assembly 110 may be wound in a cylindrical shape around the winding central axis C.

The electrode 116 may include an anode 114 and a cathode 115 . And, the separator 113 separates the anode 114 and the cathode 115 and electrically insulates them. Here, the positive electrode 114 and the negative electrode 115 may be formed in a sheet shape, wound together with the separator 113, and formed in a jelly roll shape. At this time, the electrode assembly 110 may be wound in a cylindrical shape, for example. In addition, the positive electrode 114, the separator 113, and the negative electrode 115 are each a plurality of layers in the thickness direction of the electrode assembly 110 perpendicular to the winding central axis C of the electrode assembly 110 can form

The anode 115 may include an anode current collector and an anode active material coated on the anode current collector.

In addition, the negative electrode 115 may have a negative electrode uncoated region, which is an area where the negative electrode current collector is not coated with the negative electrode active material.

The anode current collector may be formed of, for example, a foil made of copper (Cu) or nickel (Ni). The anode active material may include, for example, artificial graphite, lithium metal, lithium alloy, carbon, petroleum coke, activated carbon, graphite, a silicon compound, a tin compound, a titanium compound, or an alloy thereof. At this time, the negative electrode active material may further include, for example, non-graphite-based SiO (silica) or SiC (silicon carbide).

The cathode 114 may include a cathode current collector and a cathode active material coated on the cathode current collector.

In addition, the positive electrode 114 may be formed with a positive electrode plain layer, which is an area where the positive electrode active material is not applied to the positive electrode current collector.

The cathode current collector may be made of, for example, aluminum foil, and the cathode active material may include, for example, lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, lithium iron phosphate, or one or more of these. compounds and mixtures, and the like.

The separator 113 is made of an insulating material and is alternately laminated with the anode 114 and the cathode 115 . Here, the separator 113 may be positioned between the positive electrode 114 and the negative electrode 115 and on the outer surface of the positive electrode 114 and the negative electrode 115 . In this case, the separator 113 may include a first separator 111 and a second separator 112 . Meanwhile, the separator 113 may also be positioned on the outermost side O in the width direction when the electrode assembly 110 is wound.

In addition, the separator 113 may be made of a flexible material. At this time, the separator 113 may be formed of, for example, a polyolefin-based resin film having microporous properties such as polyethylene and polypropylene.

Meanwhile, the electrode assembly 110 according to the embodiment of the present invention may further include an electrode tab 150.

The electrode tab 150 is attached to the electrode 116 and electrically connected to the electrode 116 .

Meanwhile, the electrode tab 150 may include a positive electrode tab 151 attached to the positive electrode 114 and a negative electrode tab 152 attached to the negative electrode 115 .

The positive electrode tab 151 may be provided on the positive electrode uncoated portion, and the negative electrode tab 152 may be provided on the negative electrode uncoated portion.

The battery case 170 may accommodate the electrode assembly 110 and the center member 120 . Here, the electrode assembly 110 and the center member 120 may be accommodated in the accommodation space 171 formed inside the battery case 170 . At this time, the secondary battery 100 according to the embodiment of the present invention further includes an electrolyte solution, so that the electrolyte solution can be accommodated in the accommodation space 171 of the battery case 170 .

4 is a cross-sectional view showing a melted state of a center member in a secondary battery according to an embodiment of the present invention.

Referring to FIGS. 1 to 4 , the center member 120 may be positioned at the winding center of the electrode assembly 110 .

The center member 120 may be positioned at the winding center of the electrode assembly 110 to provide a reference axis or reference plane when the electrode assembly 110 is wound. Here, the electrode assembly 110 may surround the center member 120 and be wound around the center member 120 . Accordingly, when winding the positive electrode 114, the separator 113, and the negative electrode 115, the meandering alignment of the positive electrode 114, the separator 113, and the negative electrode 115 is captured through the center member 120. (For reference, meandering refers to a phenomenon in which the winding is not rolled evenly but at an angle).

In addition, the center member 120 is provided on the core side (I), which is the winding center of the electrode assembly 110, and the electrode is positioned on the core side (I) of the electrode assembly 110 as the charge/discharge cycle progresses. Breaking of (116) can be prevented. At this time, the positive electrode 114, the separator 113, and the negative electrode 115 are wound around the outer circumferential surface of the center member 120, and the electrode assembly 110 is perpendicular to the winding central axis C of the electrode assembly 110. A plurality of layers may be formed in the thickness direction of each.

Meanwhile, the electrode assembly 110 may be wound while being fixed to the center member 120 with a tape. If the tape fixing method is used, the degree of meandering alignment during winding can be further improved.

In addition, the center member 120 may be formed in a tubular shape having an accommodating portion 121 therein. At this time, the center member 120 may be formed in a cylindrical shape.

The center member 120 may have an accommodating portion 121 accommodating the gas absorbent 130 therein. Here, the accommodating part 121 may be in a sealed form.

Therefore, the accommodating portion 121 of the center member 120 in which the gas absorbent 130 is accommodated is sealed until the center member 120 is melted, and when the secondary battery rapidly generates gas at a high temperature, the center member 120 Melting is performed, the sealing of the accommodating portion 121 is released, and the gas absorbent 130 may be exposed to the outside of the center member 120 . That is, when the center member 120 is melted by high heat, the gas absorbent 130 is exposed and the gas inside the battery case 170 is absorbed to prevent the secondary battery from exploding at high pressure due to rapid gas generation. (Reference Figure 4)

The center member 120 may be melted at, for example, 120° C. or higher. Here, specifically, for example, the center member 120 may be melted at 120 to 160°C. At this time, more specifically, for example, the center member 120 may be melted at 120 to 150°C.

Accordingly, the center member 120 is melted at 160° C. or less, and various safety problems such as evaporation of the electrolyte and thermal runway of the anode and the cathode may be prevented from occurring. In addition, since the center member 120 is melted at 160° C. or less, it is possible to prevent an explosion due to a rise in internal pressure.

In addition, since the center member 120 is melted at 120° C. or higher, melting at a general cell ignition temperature can be prevented.

Therefore, the center member 120 is melted at 120° C. or higher, so that the gas absorbent 130 can be prevented from being exposed before the electrode assembly 110 generates high heat or ignites. That is, the center member 120 is not melted by heat generated during charging and discharging of a normal secondary battery, but is melted by high heat or heat generated during ignition, so that the gas absorbent 130 may be exposed.

In addition, the center member 120 is melted at 160° C. or lower, so that the gas absorbent 130 can be effectively exposed when gas is rapidly generated due to high heat generation or ignition of the electrode assembly 110 . That is, since the center member 120 is melted from the initial stage of ignition or rapid gas generation, it is possible to prevent the secondary battery from exploding due to an increase in internal pressure due to an increase in internal gas.

In addition, the center member 120 may include a plastic material. Also, the center member 120 may be made of a polypropylene (PP) material.

The gas absorbent 130 may be accommodated inside the center member 120 .

In addition, the gas absorbent 130 may remove H2O component gas by using, for example, calcium chloride or sulfuric acid material. At this time, the gas absorbent 130 may further use zeolite or porous silica, which is a high poly structure for removing CO2 gas.

In addition, the gas absorbent 130 may include, for example, at least one of potassium hydroxide, sodium hydroxide, barium hydroxide, soda lime, and ascarite. Accordingly, when the secondary battery 100 rapidly generates gas due to high heat or ignition, the center member 120 melts and absorbs carbon dioxide in the secondary battery 100 to prevent the secondary battery 100 from exploding. . In this case, the gas absorbent 130 further includes an ammoniacal or acidic copper (I) chloride solution, and is exposed during melting of the center member 120 and can further absorb carbon monoxide.

Meanwhile, a battery pack may be configured including the secondary battery 100 according to the embodiment of the present invention configured as described above.

The battery pack may include a plurality of secondary batteries 100 and a pack case accommodating the plurality of secondary batteries 100 .

Although the present invention has been described in detail through specific examples, this is for specifically explaining the present invention, and the present invention is not limited thereto. It will be said that various implementations are possible by those skilled in the art within the technical spirit of the present invention.

In addition, the specific protection scope of the invention will be clarified by the appended claims.

100: secondary battery
110: electrode assembly
111 anode
112 cathode
113: electrode
114: first separator
115: second separator
116 Separator
120: center member
121: receiving part
130: gas absorbent
150: electrode tab
151: anode tab
152: cathode tab
160: cap
170: battery case
171: accommodation space
C: winding central axis
O: outer side
I: core side

Claims (10)

An electrode assembly in which electrodes and separators are alternately stacked and wound;
a center member positioned at a winding center of the electrode assembly;
a gas absorbent accommodated inside the center member; and
A battery case in which the electrode assembly and the center member are accommodated,
When the center member is melted by heat, the gas absorber is exposed and gas inside the battery case is absorbed. The method of claim 1,
The center member is a secondary battery that is melted at 120 ° C or higher. The method of claim 2,
The center member is a secondary battery that is melted at 120 to 160 ° C. The method of claim 1,
The secondary battery of claim 1 , wherein the center member has an accommodating portion accommodating the gas absorbent therein. The method of claim 4,
A secondary battery wherein the receiving portion of the center member is in a sealed form. The method of claim 4,
The secondary battery wherein the center member is formed in a tubular shape. The method of claim 6,
The secondary battery wherein the center member is formed in a cylindrical shape. The method of claim 1,
The secondary battery wherein the center member includes a plastic material. The method according to any one of claims 1 to 8,
The center member is a secondary battery made of PP (polypropylene, polypropylene) material. A battery pack comprising the secondary battery according to any one of claims 1 to 8.

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