KR20200057971A - Method of manufacturing lithium ion secondary battery comprisng stacking type electrode assembly - Google Patents

Abstract

Provided are a method for manufacturing a new secondary battery, capable of preventing contamination and/or electrolyte solution reduction due to long-term aging of a battery container under an unsealed state, and an aging device thereof. According to the present invention, the secondary battery has an effect of preventing contamination or evaporation of the electrolyte even if the battery container in which an electrode assembly is accommodated undergoes a long-term aging in an open state after injection of the electrolyte.

Description

Manufacturing method of a lithium secondary battery including a stacked electrode assembly {METHOD OF MANUFACTURING LITHIUM ION SECONDARY BATTERY COMPRISNG STACKING TYPE ELECTRODE ASSEMBLY}

The present invention relates to a method of manufacturing a lithium secondary battery including a stacked electrode assembly, and specifically, to a method of manufacturing a secondary battery including an electrode assembly that takes a long time to impregnate an electrolyte and an aging device therefor.

As the price of energy sources increases due to the exhaustion of fossil fuels, and interest in environmental pollution is amplified, the demand for eco-friendly alternative energy sources has become an indispensable factor for future life, especially technology development for mobile devices. Demand for secondary batteries as an energy source is rapidly increasing as the demand for electricity increases.

Typically, the shape of the battery has a high demand for prismatic secondary batteries and pouch-type secondary batteries that can be applied to products such as mobile phones with a thin thickness, and in terms of materials, lithium ion batteries with high energy density, discharge voltage, and output stability, There is a high demand for lithium secondary batteries such as lithium ion polymer batteries.

Lithium secondary batteries are roughly classified into cylindrical batteries, prismatic batteries, and pouch-type batteries according to the external and internal structural characteristics. Among them, prismatic batteries and pouch-type batteries that can be stacked with high integration and have a small width to length are particularly It is getting attention.

On the other hand, the electrode assembly of the anode / separator / cathode structure constituting the secondary battery is largely divided into a wound type (jelly-roll type) and a laminated type (stack type) depending on its structure.

The wound electrode assembly is coated with an electrode active material on a metal foil used as a current collector, dried and pressed, cut into a band shape having a desired width and length, and a positive electrode and / or a negative electrode is directly contacted using a separator. It is manufactured by winding it in a spiral after blocking it.

However, the wound electrode assembly is suitable for a cylindrical battery, but when applied to a prismatic or pouch-shaped battery, a problem of peeling of the electrode active material may occur, and space that cannot be utilized due to the characteristics of the winding and manufacturing method inevitably occurs. There is a disadvantage in that space utilization is poor.

On the other hand, the stacked electrode assembly has a structure in which a plurality of anode and cathode unit cells are sequentially stacked, and has excellent compactness, but has superior space utilization, high integration, and easy to obtain a square shape compared to the above-mentioned wound electrode assembly. Although there is an advantage, there is a problem in that the manufacturing process is complicated and an electrode is easily pushed by an external impact, causing a short circuit.

Therefore, in order to ensure stability when applying the stacked electrode assembly, it is preferable to use a sturdy can-shaped square battery cell rather than a pouch-type battery cell.

On the other hand, since the stacked electrode assembly is poor in electrolyte impregnation due to its dense structural characteristics, it requires a long aging process until the injected electrolyte is impregnated into the electrode assembly after injection of the electrolyte.

In the case of a pouch-type battery with a built-in electrode assembly, the electrolyte is impregnated through a process of aging for about 3 days in a sealed state after injection of the electrolyte, and gas is generated inside the battery as a side reaction. The gas in the pouch is removed through a degasing process and then resealed.

However, the prismatic secondary battery cannot perform the degassing process performed in the pouch-type battery. Therefore, when a stacked electrode assembly is embedded in a prismatic secondary battery, in order to discharge gas due to side reactions, aging must be performed for a long time in a state where the battery is inevitably opened. At this time, as the electrolyte is exposed to the outside air for a long time, a problem of evaporation or contamination may occur.

In this regard, Korean Registered Patent No. 1809113 introduces a non-incisional gas removal process that first performs activation through initial charging prior to the aging process of dispersing the electrolyte solution, and then performs aging while simultaneously removing the gas inside the battery. , Non-aqueous electrolyte is proposed to include a SEI film forming agent. According to the above method, it is possible to reduce side reaction gas without cutting and / or degassing the battery.

However, even with the above method, variations in gas removal efficiency may occur depending on process conditions, and there is still a problem that it is difficult to completely remove side reaction gases.

Korean Registered Patent No. 1809113

The present invention provides a method for manufacturing a new secondary battery capable of preventing a decrease in electrolyte and / or contamination problems caused by long-term aging in the prior art while embedding a highly dense and efficient stacked electrode assembly into a square battery having excellent stability. do.

In addition, an aging device required for manufacturing a secondary battery according to the present invention is also provided.

In order to solve the above problems, the method of manufacturing a secondary battery according to the present invention may include the following steps.

Preparing an electrode assembly having a separator interposed between the positive electrode plate and the negative electrode plate (s1);

Injecting the electrode assembly into a battery container and injecting an electrolyte solution (s2);

Storing the battery container in which the electrolyte solution is injected into a storage box (s3);

Injecting and sealing nitrogen gas into the storage box in which the battery container is stored (s4);

Aging the battery container housed in the sealed storage box (s5); And

Step of taking out and sealing the battery container stored in the storage box (s6).

At this time, the electrode assembly incorporated in the battery container may be either a wound type or a stacked type, but may preferably be a stacked electrode assembly.

Meanwhile, the battery container of step s3 may be housed in a storage box in an open state in which the upper portion of the battery container is not sealed after the electrode assembly is embedded and the electrolyte is injected. At this time, the battery container to be stored is preferably stored in a vertical direction with respect to the bottom surface of the storage box, so that even if the top of the battery container is opened, the injected electrolyte does not flow out.

After the nitrogen gas is injected in the step s4, the internal pressure of the storage box may be preferably 0.1 to 2 Mpa, more preferably 0.5 to 1 Mpa.

In addition, when nitrogen gas is injected into the storage box and the box is sealed and the box is stored (step s5), the external temperature may be preferably 10 to 50 ° C, more preferably 23 to 40 ° C. In addition, the aging step of s5 may be preferably performed for 48 to 72 hours, more preferably for 54 to 60 hours.

The storage box is preferably made of a material that can be sealed, and more preferably, may be made of a flame-retardant material to prevent the risk of fire due to an increase in external temperature or spark. At this time, as the flame-retardant material, a plastic material or an insulating metal material containing a flame-retardant material may be used.

The method for manufacturing a secondary battery according to the present invention is preferable for a cylindrical and / or stacked can type battery, and more particularly, it is more preferably applied to a square secondary battery capable of efficiently embedding a stacked electrode assembly.

On the other hand, the secondary battery manufacturing method according to the present invention includes a storage groove for storing a battery container having an electrode assembly, a nitrogen gas supply pipe for injecting nitrogen gas, and

It includes a discharge pipe for discharging the internal air, the upper storage box body is open; And a cover member having a structure that covers an open area of the storage box body.

According to an embodiment of the present invention, the aging device may further include a sealing member and a sealing groove for sealing the storage box body and the cover member.

In addition, the storage groove may be formed in a shape corresponding to the lower surface of the battery container so that the battery container can be stored vertically.

In addition, according to another embodiment of the present invention, in order to more stably fix the stored battery container, the storage box main body further includes a support projecting upward from the lower surface of the storage box main body in a direction toward an open surface. can do.

In the secondary battery according to the present invention, even if the battery container containing the electrode assembly undergoes an aging process for a long time in an open state after the electrolyte is injected, there is an effect that the electrolyte does not evaporate or contaminate.

1 is a graph showing the difference in EIS characteristics of a cylindrical test cell according to moisture content.
2 is a graph showing the difference in cycle characteristics of a cylindrical test cell according to moisture content.
3 is a plan view of a battery container storage box body according to an embodiment of the present invention.
Figure 4 shows a bottom view of the cover member according to an embodiment of the present invention.
5 is a plan view of a main body of a battery paper storage box according to another embodiment of the present invention.
6 is a perspective view of a main body of a battery paper storage box according to another embodiment of the present invention.
7 is a perspective view of a battery paper storage box body according to another embodiment in which the support of the present invention is installed.
8 is a perspective view of a main body and a cover portion of a battery container storage box according to another embodiment of the present invention.

The terms used in the present specification and claims should not be interpreted as being limited to a conventional or dictionary meaning, and the inventor can appropriately define the concept of terms in order to explain his or her invention in the best way. Based on the principle, it should be interpreted as meanings and concepts consistent with the technical idea of the invention. Therefore, the configuration shown in the embodiments described herein is only one of the most preferred embodiments of the present invention and does not represent all of the technical spirit of the present invention, and various equivalents that can replace them at the time of this application And it should be understood that there may be variations.

Throughout the present specification, when a part “includes” a certain component, it means that the component may further include other components, not to exclude other components, unless otherwise stated.

The description of "A and / or B" in the present specification means "A or B or both".

Hereinafter, the present invention will be described in more detail.

The present invention provides a method of manufacturing a secondary battery in which the electrolyte solution is not reduced or contaminated even after a long-term aging process without sealing the battery container in which the electrode assembly is embedded.

In general, in manufacturing a battery cell, an electrolyte solution is injected into a battery container in which the electrode assembly is embedded, and then an aging process is performed to ensure that the electrolyte solution is sufficiently dispersed in the electrode assembly. However, in the case of the stacked electrode assembly, because of the structural characteristics, the dispersion rate of the electrolyte is slow, so the aging process is inevitably lengthened.

In the case of a pouch-type secondary battery, it is possible to maintain the battery shape by removing gas through a degassing process after an activation process, removing a gas pocket, and sealing according to the shape. On the other hand, in a can-type secondary battery, when a long-term aging process is required, the aging process is usually performed without sealing the battery container, so that the generated gas is discharged directly to the outside air.

However, when the aging process is performed for a long time without sealing the battery container, there is a problem in that contaminants contained in the outside air, particularly moisture, flow into the battery container and deteriorate the performance of the battery. When the moisture content inside the battery is too high due to the inflow of moisture in the atmosphere, the interface resistance increases, and the performance of the battery may decrease, such as the cycle characteristics of the battery decrease.

In this regard, FIG. 1 is a view showing the results of preparing and experimenting with a cylindrical test cell, which is a commonly used secondary battery, in order to examine the effect of moisture content inside the battery on battery performance. Specifically, four conventional cylindrical test cells were prepared as the same, and the moisture content inside the cells was changed to 300 ppm, 500 ppm, 700 ppm, and 900 ppm, respectively, and EIS measurements were made, and the difference was illustrated in a graph.

The EIS measurement results are usually expressed as a Nyquist plot on an impedance complex plane. The Nyquist plot is a method of plotting the imaginary part of the impedance on the y-axis and the real part on the x-axis according to a change in frequency. Figure 1 shows the water content of each of the cylindrical test cell is set differently, EIS characteristics are shown in a Nyquist plot. In this case, the total impedance Z of the battery is divided into a real impendence component (Z 'or Z _real ) and an imaginary impedance component (Z "or Z _img ) for each applied frequency.

As shown in Fig. 1, the impedance values of the cylindrical test cells having a water content of 300 ppm, 500 ppm, 700 ppm, and 900 ppm are shown in a Nyquist plot, respectively. It can be observed that the impedance characteristic curve changes due to the change. In the Nyquist plot, the plot distance of each curve that is different depending on the moisture content indicates the magnitude of the interface resistance. At this time, the interface resistance is related to whether or not the inefficient mass transport due to diffusion of the electrolytic material exhibits a certain resistance to charge transfer, and it can be determined that the performance of the battery decreases as the interface resistance increases. In FIG. 1, it can be seen that as the moisture content inside the battery increased from 300 ppm to 900 ppm, the interface resistance increased and the battery characteristics deteriorated.

On the other hand, Figure 2 shows the cycle characteristics according to the moisture content for the same cylindrical test cell as in Figure 1 above. It can be seen that as the moisture content increases, the cycle characteristics decrease, and particularly in the case of a test cell having a moisture content of 900 ppm, the cycle characteristics rapidly decrease.

Accordingly, in order to solve the above problems, the present invention provides a method for manufacturing a can-type secondary battery having excellent performance by blocking contaminants such as moisture from entering the battery even though the battery container is subjected to a long-term aging process in an unsealed state. do.

Hereinafter, a method of manufacturing a secondary battery according to an embodiment of the present invention will be described in detail.

An electrode assembly having a separator interposed between the positive electrode plate and the negative electrode plate is prepared. At this time, the electrode assembly may be a stacked electrode assembly that easily achieves a high capacity but has a slow electrolyte impregnation rate.

The electrode assembly includes an electrode stack in which two electrodes having opposite polarities are alternately stacked through a separator, and the electrode may be a cathode or an anode, and the separator is interposed between the anode and the cathode to electrically connect them. Insulate.

The positive electrode may include, for example, a positive electrode current collector made of aluminum (Al) and a positive electrode active material layer formed by coating a positive electrode active material on one or both surfaces thereof. Similarly, the negative electrode may include a negative electrode active material layer formed by applying a negative electrode active material to a copper current collector and one surface thereof.

As the positive electrode active material, for example, LiCoO ₂ , LiNiO ₂ , LiNi _1-y Co _y O ₂ (0 <y <1), LiMO ₂ (M = Mn, Fe, etc.), Li (NiaCobMnc) O ₂ (0 <a <1, 0 <b <1, 0 <c <1, a + b + c = 1), a layered positive electrode active material such as LiNi _1-y Mn _y O ₂ (O≤y <1); LiMn ₂ O ₄ , LiMn _2-z Co _z O ₄ (0 <z <2), LiMn _2-z Ni _z O ₄ (0 <z <2), Li (Ni _a Co _b Mn _c ) O4 (0 < spinel type positive electrode active materials such as a <2, 0 <b <2, 0 <c <2, a + b + c = 2); An olivine-type positive electrode active material such as LiCoPO ₄ or LiFePO ₄ may be used.

In addition, the negative electrode active material, for example, petroleum coke (petroleum coke), activated carbon (activated carbon), graphite (graphite), non-graphitized carbon, carbon-based materials such as graphite carbon; Li _x Fe ₂ O ₃ (0≤x≤1), Li _x WO ₂ (0≤x≤1), Sn _x Me _1-x Me ' _y O _z (Me: Mn, Fe, Pb, Ge; Me' : Al, B, P, Si, group 1, group 2, group 3 elements of the periodic table, halogen; metal composite oxide of 0 <x≤1;1≤y≤3;1≤z≤8); Lithium metal; Lithium alloys; Silicon-based alloys; Tin-based alloys; SnO, SnO ₂ , PbO, PbO ₂ , Pb ₂ O ₃ , Pb ₃ O ₄ , Sb ₂ O ₃ , Sb ₂ O ₄ , Sb ₂ O ₅ , GeO, GeO ₂ , Bi ₂ O ₃ , Bi ₂ O ₄ , Oxides such as Bi ₂ O ₅ ; Conductive polymers such as polyacetylene; Li-Co-Ni-based materials and the like can be used.

The separator serves as an ion-conducting barrier that passes ions while blocking electrical contact between the anode and the cathode. It may be made of a porous polymer substrate having a plurality of fine pores. Furthermore, the separator may be formed with a porous coating layer comprising a plurality of inorganic particles and a polymer binder resin on the surface of the porous polymer substrate. The porous coating layer is a layer in which inorganic particles in the coating layer are integrated by point bonding and / or face bonding via a binder resin, and the coating layer has a porous structure due to interstitial volume between inorganic particles. .

Meanwhile, as the porous polymer substrate, for example, polyolefin, polyethylene terephthalate, polybutylene terephthalate, polyacetal, polyamide, polycarbonate, polyimide, polyether ether ketone, polyether sulfone, polyphenylene oxide, poly There are porous polymer substrates formed of at least one of polymer resins such as phenylene sulfide and polyethylene naphthalene, but are not particularly limited thereto. In addition, as the porous polymer substrate, any of a sheet-like film formed by melting a polymer resin and a filament obtained by melt spinning a polymer resin may be used. It is preferably a porous polymer substrate manufactured in a sheet form by melting / molding the polymer resin.

The electrode assembly can be manufactured in both a wound type and a laminated type. However, as described above, in the case of a stacked electrode assembly that requires a long aging process, there is a high possibility that contaminants are introduced, and thus a better effect may be exhibited. According to the method of manufacturing a secondary battery of the present invention, since the amount of the electrolyte is not reduced or the electrolyte is not contaminated during a long-term aging process, the electrode assembly of the stacked structure having a relatively slow impregnation and / or dispersion rate is included. The effect is most excellent when applied to each type of can type battery, where the degassing process is impossible.

According to an embodiment of the present invention, after the electrode assembly is embedded in a battery container, an electrolyte is injected. After that, the upper portion of the battery container is stored in the storage box without sealing, and aging is performed. The stacked electrode assembly, unlike the wound electrode assembly, has a slow electrolyte impregnation rate, so the aging time can be preferably 48 to 72 hours, more preferably 54 to 60 hours. If the aging time is less than 48 hours, the electrolyte is not sufficiently dispersed, and if it exceeds 72 hours, the manufacturing process may be excessively long, resulting in a decrease in production efficiency.

The electric container can be used for both the pouch type and / or each type, but in the case of the pouch type, the gas can be discharged without reducing or polluting the electrolyte by performing a degassing process after sealing and aging. It is more suitable for invention.

According to one embodiment of the present invention, the stacked electrode assembly is built into each type of battery container, and the electrolyte is injected, and then stored in the storage box body of the aging device according to the present invention. At this time, it is preferable that the upper end of the battery container is sealed and stored in an open state so that gas generated by side reactions can be discharged.

On the other hand, since the upper end of the battery container is open, it is preferable that the battery container is stored in the vertical direction with respect to the bottom surface of the storage box body so that the electrolyte does not leak. To this end, according to an embodiment of the present invention, a storage groove corresponding to a bottom surface shape of the electric container is formed on the bottom surface of the storage box body, and the electric container can be mounted to the storage groove and fixed in a vertical direction. .

Then, after the storage box body is covered with the cover member of the aging device, nitrogen gas is injected from the nitrogen gas supply pipe connected to the storage box body or the cover member, and air remaining in the box is discharged through the discharge pipe. Then, after closing the outlet, when the pressure inside the storage box is 0.1 to 2 MPa, preferably 0.5 to 1 Mpa, the supply of nitrogen gas is stopped and the storage box is sealed. At this time, the pressure of the internal nitrogen gas can be arbitrarily adjusted within the above-mentioned range, but if it is less than 0.1 Mpa, the air in the box is pushed out and difficult to discharge, and some air remains. Also, when it exceeds 2Mpa, the stability of the battery container in which the electrolyte solution and the electrode assembly are embedded may be deteriorated, which is not preferable.

Aging is performed by storing the battery container in the sealed storage box so that the electrolyte is sufficiently dispersed inside the battery container. At this time, the storage box may be stored at an external temperature of 10 to 50 ° C, more preferably 23 to 40 ° C. If the outside temperature is too low outside the above range, the electrolyte impregnation rate may be lowered, and the electrolyte may not be sufficiently dispersed even after the aging process.

On the other hand, since the electrolyte solution injected into the battery container is generally volatile and flammable, there is a risk of ignition if the temperature rises rapidly or sparks occur during long-term storage. Therefore, it is preferable that the storage box body and the cover member are made of a flame retardant material. The aging process does not usually perform charging and discharging, but since the battery container in which the highly volatile electrolyte solution is injected is dense and can be ignited, the storage box is preferably made of a flame retardant material. Specifically, the flame-retardant material may be appropriately selected in consideration of mechanical strength and flame-retardant properties among the plastic material and the insulating metal material including the flame-retardant material.

Hereinafter, the aging process using the aging device of the present invention will be described in detail with reference to Examples and Comparative Examples to help understanding of the present invention. However, the embodiments according to the present invention can be modified in many different forms, and the scope of the present invention should not be construed as being limited by the following examples. The embodiments of the present invention are provided to more fully describe the present invention to those skilled in the art.

Comparative Example 1

A storage box body 100 for storing a battery container as shown in FIG. 3 was manufactured. In the storage box body, a sealing groove 110 for sealing and a storage groove 120 for storing a battery container are formed.

After receiving the battery container in the storage groove 120, the cover member 200 shown in FIG. 4 is covered with the storage box body 100 and sealed to prevent external air from entering. At this time, in the cover member 200, a sealing member 210 for maintaining a sealed state by combining with the sealing groove 110 of the storage box body 100 was formed at a position corresponding to the sealing groove 110.

The storage box body 100 shown in FIG. 3 and the cover member 200 shown in FIG. 4 were used to store one battery container and then perform an aging process at room temperature (23 ° C.) for 60 hours. As a result, a small amount of moisture was detected inside the battery. This is judged to be because a small amount of moisture present in the air inside the storage box has flowed into the battery container.

Example 1

In order to completely discharge the air remaining inside the storage box, a nitrogen gas supply pipe 130 for injecting nitrogen gas into the storage box body 100 as shown in FIG. 5 and an exhaust pipe 140 for discharging air therein A storage box body according to another embodiment was manufactured. Valves are attached to the nitrogen gas supply pipe 130 and the discharge pipe 140, respectively, so that the amount of nitrogen gas input and the pressure inside the storage box can be adjusted when sealed.

After storing one battery container by using the storage box main body according to FIG. 5 and the cover member according to FIG. 4, the valves of the nitrogen gas supply pipe 130 and the discharge pipe 140 are opened to sufficiently discharge the air inside the storage box. Then, the valve of the discharge pipe 140 was closed, and when the internal pressure became 1 Mpa, the valve of the nitrogen gas supply pipe 130 was closed, and then an aging process was performed at room temperature (23 ° C.) for 60 hours. As expected, moisture entering the battery container was not detected.

Subsequently, a number of battery containers were manufactured to store the battery containers in all the storage grooves formed in the storage box body of FIG. 5 and the cover member of FIG. 4, respectively, and an aging process was performed. However, during the storage operation of the battery container, an unexpected problem occurred in which some of the battery containers collapsed and the internal electrolyte was leaked. It was expected that the same problem would occur even if an external impact occurred during aging or the aging device was moved.

Example 2

In order to solve the above-described problem, in accordance with another embodiment, two support holders 150 protruding upward from the lower surface of the storage box body around the receiving groove in an open direction are installed for each groove. 6 and 7 show and compare the perspective view of the storage box body before and after installation of the support.

Afterwards, as shown in FIG. 8, the aging process was performed in the same manner as in Example 1, except that the support was installed by sealing all the battery containers in each storage groove and sealing them with a cover member. No problems occurred at.

100: storage box body
110: sealing groove
120: storage groove
130: nitrogen gas supply pipe
140: discharge pipe
150: support
200: cover member
210: sealing member

Claims (13)

Preparing an electrode assembly having a separator interposed between the positive electrode plate and the negative electrode plate (s1);
Injecting the electrode assembly into a battery container and injecting an electrolyte solution (s2);
Storing the battery container in which the electrolyte solution is injected into a storage box (s3);
Injecting and sealing nitrogen gas into the storage box in which the battery container is stored (s4);
Aging the battery container housed in the sealed storage box (s5); And
A method of manufacturing a secondary battery comprising a; step of taking out and sealing the battery container stored in the storage box (s6).
According to claim 1,
The electrode assembly is a method of manufacturing a secondary battery that is a stacked electrode assembly.
According to claim 1,
The method of manufacturing a secondary battery in which the battery container of step s3 is stored in an open state of an upper portion of the battery container.
According to claim 1,
The method of manufacturing a secondary battery in which the battery container of step s3 is stored in a vertical direction with respect to the bottom surface of the storage box.
According to claim 1,
The method of manufacturing a secondary battery in which the internal pressure of the storage box is 0.1 to 2 Mpa after nitrogen gas is injected in the step s4.
According to claim 1,
In the step s5, the storage box is a method of manufacturing a secondary battery, which is stored in a state where the external temperature is 10 to 50 ° C.
According to claim 1,
The s5 step is a method of manufacturing a secondary battery that is performed for 48 to 72 hours.
According to claim 1,
The storage box is a method of manufacturing a secondary battery made of a flame retardant material.
According to claim 1,
The secondary battery is a method of manufacturing a secondary battery that is a prismatic secondary battery.
Storage groove for storing a battery container with an electrode assembly,
Nitrogen gas supply pipe for injecting nitrogen gas and
It includes a discharge pipe for discharging the internal air,
A storage box body with an open top; And
A secondary battery aging device comprising a; cover member having a structure covering an open area of the storage box body.
The method of claim 10,
A secondary battery aging device in which a sealing member and a sealing groove for sealing are formed in the storage box body and the cover member.
The method of claim 10,
The storage groove is a secondary battery aging device that is in a form corresponding to the lower surface of the battery container so that the battery container can be stored vertically.
The method of claim 10,
The storage box main body further comprises a support for protruding upward in the direction of one surface opened from the lower surface of the storage box main body.

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