KR101476523B1 - Electrode of secondary battery - Google Patents

Abstract

There is provided an electrode of a secondary battery in which a stress generated on a positive electrode or a negative electrode in a lithium ion secondary battery employing a fixed electrode laminate structure is reduced. The electrode of the secondary battery according to the present invention is composed of a laminated electrode body 101 in which a positive electrode 10, a separator 30 and a negative electrode 20 are alternately laminated, and a fixing portion 40), and the rigidity of the positive electrode and / or the negative electrode facing the separator is lower than that in the vicinity of the fixed portion.

Description

ELECTRODE OF SECONDARY BATTERY [0002]

The present invention relates to an electrode of a secondary battery used in an electric automobile or the like.

BACKGROUND ART [0002] In a secondary battery used in an electric vehicle or the like, a laminated electrode body in which a positive electrode or a negative electrode formed by applying a positive electrode or a negative electrode active material to both surfaces of a current collector is laminated with a separator interposed therebetween is often constituted. Such a laminated secondary battery tends to cause a displacement of lamination in the electrode body due to external vibrations, and therefore a technique of fixing the laminated electrode body in the lamination direction has been studied. For example, Patent Document 1 discloses a technique of forming a penetrating portion for fixing a laminated electrode body to an area deviating from an active region used for an electrode reaction.

Japanese Patent Application Laid-Open No. 2010-232145

However, the electrode repeats the expansion and contraction of the active material layer due to the insertion / removal of lithium by charging / discharging. Therefore, when the positive electrode and the negative electrode are fixed in the lamination direction in the laminated electrode body as in the above-described Patent Document 1, the surfaces of the positive electrode active material layer and the negative electrode active material layer expand or shrink starting from the fixed portion, Deformation occurs. If the stress generated in the active material layer is increased, the electrode layer may be collapsed or peeled off, thereby causing internal short-circuiting of the secondary battery. And the electrode layer is likely to be short-lived.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide an electrode of a secondary battery in which a stress generated on a positive electrode or a negative electrode in a lithium ion secondary battery employing a fixed laminated electrode structure is reduced .

The present invention for achieving the above object has a laminated electrode body in which a positive electrode, a separator and a negative electrode are alternately laminated, and a fixing portion for fixing the laminated electrode body in the lamination direction. And the rigidity of the positive electrode and / or the negative electrode is lower in the distal portion than in the vicinity of the fixed portion.

According to the electrode of the secondary battery according to the present invention, the deformation caused by the expansion and contraction of the laminated electrode body generated from the fixed portion by the charge / discharge reaction becomes larger as the distance from the fixed portion increases. And the lower the distance from the government. As a result, deformation of the circular portion from the fixing portion caused by charging / discharging of the secondary battery is allowed compared with the adjacent portion, so that the stress generated in the positive electrode or the negative electrode can be reduced.

By reducing the stress generated on the surface of the positive electrode or the negative electrode in this manner, it is possible to suppress the dislocation and peeling of the electrode layer and also to suppress internal short-circuiting of the secondary battery, thereby improving the life of the battery.

1 is a sectional view showing a stacked secondary battery;
2 is a plan view showing a positive electrode according to the present invention.
3 is a sectional view taken along line 3-3 of Fig.
4 is a sectional view showing a modified example of the electrode of the secondary battery according to the embodiment;
5 is a plan view showing a modification of the electrode of the secondary battery according to the embodiment;
6 is a plan view showing a modified example of the electrode of the secondary battery according to the embodiment.
7 is a plan view showing a modification of the electrode of the secondary battery according to the embodiment.
8 is a plan view showing a modified example of the electrode of the secondary battery according to the present embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, the following description does not limit the technical scope and meaning of the terms described in the claims. In addition, the dimensional ratios in the drawings are exaggerated for convenience of explanation, and may differ from the actual ratios.

2 is a plan view showing a positive electrode or a negative electrode according to the present embodiment, and Fig. 3 is a sectional view taken along the line 3-3 in Fig. 2. Fig.

1 to 3, a secondary battery 100 includes a laminated electrode body 101 in which a positive electrode 10, a separator 30, and a negative electrode 20 are alternately laminated, a laminated electrode body 101, And the rigidity of the positive electrode 10 and / or the negative electrode 20 facing the separator 30 is set to be lower than that in the vicinity of the fixing portion 40 .

The rigidity of the positive electrode 10 and / or the negative electrode 20 in the present embodiment is set such that the surface roughness of the surface of the positive electrode 10 and / or the negative electrode 20 is greater than the surface roughness of the negative electrode 20 . The surface roughness is adjusted by forming a groove 50 on the surface of the positive electrode 10 and / or the negative electrode 20. Although the surface of the positive electrode 10 is shown in Figs. 2 and 3, description about the fixed portion 40 and the groove portion 50 is applied to the negative electrode 20 in the same manner.

The secondary battery 100 is sealed inside a casing 70 formed of a laminated film or the like. As a result, the impact applied to the secondary battery 100 is relaxed, and the liquid leakage from the secondary battery 100 is prevented. The positive electrode 10 is formed by applying the positive electrode active material 12 and the coating layer 60 to the surface of the positive electrode collector 11 as shown in Figs. Similarly, the negative electrode 20 is formed by applying the negative electrode active material 22 and the coating layer 60 to the surface of the negative electrode collector 21. Hereinafter, this will be described in detail.

The current collector constituting the positive electrode current collector 11 and the negative electrode current collector 21 is made of a conductive material and an active material layer is disposed on one surface or both surfaces thereof. The material constituting the current collector is not particularly limited, and for example, a metal, a conductive polymer material, or a conductive resin having a conductive filler added to a non-conductive polymer material may be employed. Examples of the conductive polymer material include polyaniline and polypyrrole, and examples of the non-conductive polymer material include polyethylene, polypropylene, and polyethylene terephthalate.

Examples of the conductive filler include metals, conductive carbon, and the like, which are excellent in conductivity, anti-satellite, or lithium ion barrier properties. The metal is not particularly limited, but preferably includes at least one kind of metal selected from the group consisting of Ni, Ti, and Al, or an alloy or metal oxide containing these metals. The conductive carbon is not particularly limited, but preferably includes at least one selected from acetylene black, carbon nanofiber, Ketjen black, carbon nanotube, and the like.

The positive electrode active material for forming the positive electrode active material layer 12 has a composition that adsorbs lithium ions during discharging and releases lithium ions upon charging. A preferable example is a lithium-transition metal composite oxide which is a composite oxide of a transition metal and lithium.

Concretely, a Li-Co composite oxide such as LiCoO ₂ , a Li · Ni composite oxide such as LiNiO ₂ , a Li · Mn composite oxide such as spinel LiMn ₂ O ₄ , a Li · Fe composite oxide such as LiFeO ₂ And those obtained by replacing a part of these transition metals with other elements. These lithium-transition metal composite oxides are excellent in reactivity and cycle characteristics, and are low-cost materials. Therefore, by using these materials for the electrodes, it is possible to form a battery having excellent output characteristics.

Examples of the positive electrode active material include transition metal oxides and sulfides such as V ₂ O ₅ , MnO ₂ , TiS ₂ , MoS ₂ and MoO ₃ , transition metal oxides such as LiFePO ₄ and lithium phosphate compounds such as PbO ₂ , AgO , NiOOH, or the like may be used. The positive electrode active material may be used alone or in the form of a mixture of two or more.

The negative electrode active material forming the negative electrode active material layer 22 has a composition capable of releasing lithium ions at the time of discharging and storing lithium ions at the time of charging. The negative electrode active material is not particularly limited as long as it is capable of reversibly intercalating and deintercalating lithium. Examples of the negative electrode active material include metals such as Si and Sn, TiO ₂ , Ti ₂ O ₃ , TiO ₂ , SiO ₂ , SiO, SnO _2, and a metal _{oxide, Li 4/3 Ti 5/} 3 O 4 or Li of lithium and transition metal such as ₇ MnN complex oxide, Li-Pb alloy, Li-Al alloy, Li, or natural graphite, artificial graphite , Carbon black, activated carbon, carbon fiber, coke, soft carbon, or hard carbon.

Among them, by using an element that alloys with lithium, it becomes possible to obtain a battery having a high energy density and a high output characteristic compared to a conventional carbon-based material. The negative electrode active material may be used alone or in the form of a mixture of two or more kinds. The element to be alloyed with lithium is not limited to the following elements but may be specifically exemplified by Si, Ge, Sn, Pb, Al, In, Zn, H, Ca, Sr, Ba, Ru, Rh, Ir, Pd, Pt, Ag, Au, Cd, Hg, Ga, Tl, C, N, Sb, Bi, O, S, Se, Te and Cl.

The method of joining the active material layer and the current collector is not particularly limited, and a conventional method can be suitably employed. For example, the adhesive may be applied by applying an adhesive between the active material layer and the current collector and bonding them, or may be bonded by hot-pressing by hot pressing.

The separator 30 is made of a porous film made of a polyolefin such as polyethylene or polypropylene having a small particle diameter so that lithium ions or the like can move by the charge and discharge reaction of the secondary battery.

The above-described positive electrode active material layer 12, the negative electrode active material layer 22 and the coating layer 60 adjacent to the positive electrode active material layer 12 face each other with the separator 30 therebetween, and the positive electrode active material layer 12, the coating layer 60, 30, a coating layer 60, and a negative electrode active material layer 22 are laminated in this order.

The adjacent positive electrode active material layer 12, the coating layer 60, the separator 30, the coating layer 60 and the negative electrode active material layer 22 constitute one unit cell layer 80. Therefore, the lithium ion battery of the present embodiment has a configuration in which a plurality of unit cell layers 80 are laminated and electrically connected in parallel.

A sealing portion for insulating the adjacent positive electrode current collector and the negative electrode current collector may be provided on the outer periphery of the unit cell layer 80. The positive electrode current collector 11 located on the outermost layers on both sides of the laminated electrode body 101 is provided with the positive electrode active material layer 12 on only one side. The arrangement of the positive electrode and the negative electrode in Fig. 1 may be reversed, and the negative electrode active material layer 22 may be disposed only on one side of the negative electrode collector 21 in the outermost layer.

The positive electrode current collector plate 11 or the negative electrode current collector 21 is provided with a positive electrode collector plate 13 or a negative electrode collector plate 23 which is electrically connected to the positive electrode 10 or the negative electrode 20. The positive electrode current collecting plate 13 and the negative electrode collecting plate 23 are sandwiched between the ends of the casing member 70 and arranged so as to lead to the outside of the casing member 70. The positive electrode current collector plate 13 or the negative electrode collector plate 23 is installed on the positive electrode current collector 11 or the negative electrode current collector 21 by ultrasonic welding or resistance welding or the like through positive electrode terminal leads and negative electrode terminal leads, .

However, the positive electrode current collector 11 may be extended to serve as the positive electrode current collector plate 13 and may be led out from the casing member 70. Similarly, the negative electrode current collector 21 may extend to form the negative electrode current collecting plate 23 and be arranged so as to be led out from the casing member 70 as well.

1 and 3, the coating layer 60 is provided on the surface of the positive electrode 10 and the negative electrode 20 opposite to the separator 30 and has a melting point higher than that of the separator 30 . The coating layer 60 has a melting point higher than that of the separator 30 even when the polyethylene forming the separator 30 is melted down at a temperature of around 140 deg. Can be interposed between the negative electrode (20). As a result, it is possible to prevent internal short-circuiting of the secondary battery 100. The material of the coating layer 60 is not particularly limited, and for example, a heat-resistant resin such as polyimide or aromatic polyamide is used.

As shown in Fig. 2, the fixing portion 40 is formed in a region deviated from the active region used for the electrode reaction in the plane of the positive electrode 10 or the negative electrode 20. In FIGS. 2 and 3, the fixing portions 40 are provided at four positions of the rectangular positive electrode 10 and the negative electrode 20, and for convenience of explanation, the current collectors 11 and 21 are omitted, 60 are positioned, and the active material layers 12, 22 are positioned at the bottom. The four points of the fixing portion 40 are located at positions where the intersection of the upper right portion and the left lower portion of FIG. 2 and the diagonal lines of the upper left portion and the lower right portion is the geometric center of the surface of the positive electrode 10 or the negative electrode 20 As shown in FIG. The fixing portion 40 integrally fixes the laminated electrode body 101, not the unit of the unit cell layer 80. [ The fixing portion 40 is not particularly limited, but is constituted by a clip in the present embodiment.

The laminated electrode assembly 101 according to the present embodiment has the positive electrode 10, the negative electrode 20 and the separator 30 laminated in a number of 10 to less than 24. The aspect ratio of the plane of the positive electrode 10 or the negative electrode 20 in Fig. 2 is preferably between 1: 1 and 1: 4.

In the case where the fixing portion 40 is provided at four places of the positive electrode 10 and the negative electrode 20, the groove portion 50 is formed in the cross section cut by the diagonal line of the fixing portion 40 shown in Fig. And is formed in the coating layer 60 in a substantially rectangular shape. In the present embodiment, the vicinity of the fixed portion 40 corresponds to the right peripheral portion and the left peripheral portion near the fixed portion in Fig. 3, and the remote portion corresponds to the portion near the fixed portion 40 And the center portion of FIG.

3, the groove portion 50 has a greater surface roughness than the right end portion and the left end portion where the fixing portion 40 is located, thereby increasing the surface roughness of the central portion of the groove portion 50 . In the present embodiment, as shown in Fig. 2, when the secondary batteries are viewed from the stacking direction, a plurality of grooves 50 are formed in a substantially concentric shape so that the surface roughness of the positive electrode 10, And rigidity are adjusted. The groove 50 can be formed by, for example, embossing or punching. The index of the surface roughness indicating the property of the groove 50 is not particularly limited, but an arithmetic mean roughness (Ra) can be used, for example. The method of measuring the shape of the groove 50 is not particularly limited, but can be performed by, for example, a sectional SEM, a probe-type roughness meter, a laser displacement meter or the like.

Adjustment of the surface roughness by the groove 50 can be performed by deepening the depth of the groove 50 more than the vicinity of the fixing portion 40 as shown in Fig. 3, the distance g between the grooves 50 may be smaller than the distance from the vicinity of the fixing portion 40. As shown in Fig.

As described above, when the laminated electrode body 101 is fixed at the four ends of the positive electrode 10 and the negative electrode 20 shown in Fig. 2, the vicinity of the center of the positive electrode 10 or the negative electrode 20 is fixed It is not in the state. When insertion and disconnection of lithium ions occurs due to the charge and discharge reaction of the battery in such a state and the expansion or contraction phenomenon occurs in the positive electrode 10 or the negative electrode 20, The stress is generated and concentrated in the part. If a stress concentration site is generated on the surface of the positive electrode 10 or the negative electrode 20, there is a fear that the electrode may collapse or the like.

On the other hand, in the present embodiment, the grooves 50 are formed on the surface of the coating layer 60 adjacent to the active material layers 12 and 22 with respect to the stress generated by the expansion and contraction. When the stress is generated and concentrated in the circular portion spaced from the fixing portion 40, the groove portion 50 is formed, so that the circular portion from the fixing portion 40 has a lower stiffness than the near portion. By making the circular portion from the fixing portion 40 have a lower stiffness than that in the vicinity of the portion, the deformation of the circular portion is allowed compared with the adjacent portion, and the generated stress can be reduced.

Further, when the groove portion 50 is excessively formed on the surface of the coating layer 60, the production facility contacting with the surface of the coating layer 60 and the abrasion are generated in the manufacturing process of the secondary battery, There is a concern. In the present embodiment, since the groove 50 is adjusted to be large only in the circular portion of the fixing portion 40, the influence on the installation can be minimized.

As described above, in the electrode of the secondary battery according to the present embodiment, the rigidity of the positive electrode 10 or the negative electrode 20 is set to be And the distal portion of the fixing portion 40 is lower than the distal portion of the fixing portion 40.

As a result, even when an external force is inputted, since the relatively long circular arc portion from the stationary portion 40 is configured to have low rigidity, large deformation is allowed compared with the adjacent portion, and the stress generated can be reduced, Peeling can be suppressed. In addition, it is possible to suppress the collapse of the electrode and the like, thereby preventing internal short-circuiting and improving the service life of the secondary battery.

The rigidity of the positive electrode 10 and / or the negative electrode 20 is set such that the surface roughness of the surface of the positive electrode 10 and / or the negative electrode 20 opposed to the separator 30 is greater than that of the vicinity of the fixing portion 40 And the circular circular arc side is enlarged. Therefore, it is possible to easily adjust the surface roughness by embossing or the like to reduce the stress generated on the surface of the positive electrode 10 and / or the negative electrode 20.

Since the surface roughness is adjusted by forming the trench 50, the stress generated on the surfaces of the positive electrode 10 and / or the negative electrode 20 can be easily reduced by embossing or the like as described above.

Further, the depth of the groove 50 is deeper than the vicinity of the fixing portion 40, and corresponds to the deformation mode that occurs when the periphery of the electrode is fixed. Therefore, the generated stress can be appropriately reduced.

Since the interval between the grooves 50 is narrower from the vicinity of the fixing part 40 toward the remote part, by narrowing the interval between the grooves 50 in the circumferential part which is relatively easily deformed, The stress can be reduced in accordance with the generated deformation.

Further, since the fixing portion 40 is provided in the region deviating from the active region used for the electrode reaction, the deterioration of the battery capacity can be prevented even if the fixing portion 40 is provided.

Further, since the active material used for the negative electrode 20 is made of an alloy, it is possible to provide a secondary battery having excellent capacity and energy density while preventing the generation of stress.

The coating layer 60 is composed of a member of a porous film having a melting point higher than that of the separator 30 so that the coating layer 60 does not shrink even if the separator 30 shrinks due to charge / It can be interposed between the negative electrode 20 and internal short circuit at high temperature can be suppressed.

The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims.

Fig. 4 is a cross-sectional view showing a modified example of the electrode of the secondary battery according to the present embodiment, and Figs. 5 to 8 are plan views showing a modified example of the electrode of the secondary battery according to the present embodiment.

Although the embodiment in which the groove 50 is formed on the surface of the coating layer 60 has been described, it is not limited thereto. Since a coating layer is not formed on the surface of the positive electrode or the negative electrode, a groove portion may be formed on the surface of the positive electrode active material layer or the negative electrode active material layer.

Further, the embodiment in which the rigidity of the positive electrode 10 and / or the negative electrode 20 is adjusted by the groove portion 50 has been described, but the present invention is not limited thereto. The rigidity may be adjusted by forming an inclined surface as shown in Fig. 4 in addition to the groove portion. By forming the inclined surface on the surface of the electrode and making the depth of the inclined surface deeper as the distance from the vicinity of the fixed portion is increased, the deformation of the circular portion is allowed more than the near portion, and the stress generated on the surface of the positive electrode or the like can be reduced.

Although the groove portion 50 has a narrow gap g from the vicinity of the fixing portion 40 toward the remote portion, the width w of the groove portion 50 shown in Fig. 3 May be adjusted to be wider from the vicinity of the fixing portion toward the circular portion.

Although the shape of the groove 50 seen from the stacking direction of the secondary battery has been described as an end shape as shown in Fig. 2, the present invention is not limited to this. The shape of the groove portion 50 is formed taking into consideration that the deformation of the coating layer or the active material layer becomes relatively large due to the expansion or contraction of the coating layer or the active material layer as the distance from the vicinity of the fixing portion 40 is increased.

Therefore, the shape of the groove portion 50 may be deeper or narrower as the groove portion 50 is separated from the fixed portion 40. As a result, the groove portion can be formed in the form of, for example, a concave dotted or striped shape as shown in Figs. 5, 6, and 7, As shown in FIG. The groove 50 in Fig. 7 is formed as shown in Fig. 3 in cross section taken along line 3-3 in the vertical direction or the horizontal direction in Fig.

When the fixing portion 40 is provided not only at the four corners but also at the central portion as shown in Fig. 8, the central portion of the fixing portion 40 and the right half of the positive electrode 10 or the negative electrode 20, An elliptical groove 50 surrounded by the central fixed portion 40 and the left half of the positive electrode 10 or the negative electrode 20 may be formed. By changing the shape of the groove portion 50 viewed from the stacking direction in accordance with the arrangement of the fixing portions 40, the stress can be reduced in accordance with the deformation mode of the electrode, which is changed by the arrangement of the fixing portions 40. [

In this way, if the laminated electrode assembly 101 can be fixed, the fixing portion 40 does not need to have the intersection of the diagonal lines of the fixing portion 40 passing through the geometric center, and the fixing portion 40 is not limited to four , Or three or two locations.

Further, although the embodiment in which the fixing portion 40 is constituted by clips has been described, it is not limited thereto. In addition to the above, the fixing portion may be configured such that a through hole is formed in the region deviated from the active region used for the electrode reaction of the positive electrode 10 or the negative electrode 20 and fixed by a screw. The fixing portion may be configured so that a screw is passed through the clip, and the width of holding the laminated electrode body by the amount of the screw is adjusted.

Further, although the embodiment in which the lithium ion secondary battery is taken as an example has been described, the present invention is not limited thereto, and the present invention is also applicable to a secondary battery other than a lithium ion secondary battery. Although the secondary battery has been described as a laminate type embodiment, it can also be applied to a bipolar type secondary battery.

(Example)

Next, the charge / discharge characteristics test of the secondary battery was performed using the electrode of the secondary battery according to the present embodiment.

In this test, the following batteries were charged at 1 C up to 4.2 V in a constant temperature state at 25 캜 under a constant current constant voltage system (CCCV), and discharged at 1 C up to 2.5 V in a constant current system (CC) 500 cycles. Then, it was confirmed whether the capacity retention rate and an internal short circuit were occurring. The number of samples is 10 in each of the Examples and Comparative Examples. Here, C represents a time rate, and 1C represents an amount of current sufficient to charge or discharge the entire capacity of the battery in one hour. For example, an amount of current of 0.5 C indicates that the entire capacity of the battery is charged or discharged for 2 hours (= 1 / 0.5 hour).

This test uses the SiO in Example 1 and Comparative Example 1 using a graphite on LiCo _2, a negative electrode to the positive electrode as in Example 2 and a comparative example 2, LiCo _2, a positive electrode and negative electrode as shown in Table 1 below Respectively.

A positive electrode plate and a negative electrode plate each having a square of 200 mm on one side were used. The number of stacked cells is 10 cells. The surfaces of the negative electrode plates of Examples 1 and 2 were pressed by a single emboss press molding machine to form concentric grooves as shown in Figs. 2 and 3. The concentric grooves were formed so that the Ra (arithmetic mean roughness) at the end portion was 2 mu m and the Ra at the center portion was 6 mu m. The experimental results are shown in Table 2.

From the results shown in Table 2, it was confirmed that the capacity retention rate of Example 1 was increased in Example 1 and Comparative Example 1, and the cycle characteristics of the battery were improved. In comparison between Example 2 and Comparative Example 2, it was confirmed that when SiO having a large expansion / shrinkage was used, not only the capacity retention rate was greatly improved but also the internal short circuit was suppressed during cycle evaluation.

The electrode after the evaluation in Comparative Example 2 and Example 2 in which the short circuit occurred as a result of the evaluation was disassembled to confirm the electrode. In Comparative Example 2, wrinkles were generated in the electrode due to expansion / contraction accompanied by charge / A local short circuit was confirmed. On the other hand, in Example 2, generation of wrinkles was not observed.

As described above, it was confirmed that by using the electrode of the secondary battery according to the present embodiment, the life of the secondary battery can be improved and the internal short circuit can be suppressed.

10: positive
11: positive electrode current collector
12: positive electrode active material layer
13: positive pole collector plate
20: negative polarity
21: anode collector
22: Negative electrode active material layer
23: anode collector plate
30: Separator
40:
50: Groove
60:
70: Outer material
80:
100: secondary battery
101: laminated electrode body

Claims (10)

A laminated electrode body in which a positive electrode, a separator and a negative electrode are alternately laminated,
And a fixing portion for fixing the laminated electrode body in the lamination direction,
Wherein the rigidity of at least one of the positive electrode and the negative electrode facing the separator is lowered as the separator is spaced apart from the fixing portion. The method according to claim 1,
Wherein the rigidity of at least one of the positive electrode and the negative electrode is such that the surface roughness of at least one of the positive electrode and the negative electrode facing the separator is increased as the distance from the fixing portion is increased. 3. The method according to claim 1 or 2,
Wherein the surface roughness is adjusted by forming a groove portion on at least one surface of the positive electrode and the negative electrode. The method of claim 3,
Wherein a depth of the groove portion is made deeper as it is spaced apart from the fixing portion. The method of claim 3,
Wherein an interval between the grooves is made narrower as the distance from the fixing portion is reduced. The method of claim 3,
And the groove portion is formed in an elliptic shape when viewed in the stacking direction of the laminated electrode bodies. The method according to claim 1,
Wherein the rigidity of at least one of the positive electrode and the negative electrode is adjusted by forming an inclined surface that becomes deeper as it separates from the fixed portion. 3. The method according to claim 1 or 2,
Wherein the fixing portion is provided in a region deviating from an active region used at the time of an electrode reaction. 3. The method according to claim 1 or 2,
Wherein the active material used for the negative electrode is made of an alloy. 3. The method according to claim 1 or 2,
Characterized in that a coating layer covering the positive electrode or the negative electrode is formed on the surface of the positive electrode or the negative electrode facing the separator and the coating layer is made of a member of a porous film having a melting point higher than that of the separator. Electrode of a battery cell.

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