JP2002110216A - Cylindrical secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cylindrical secondary battery storing a wound electrode 4 inside a sealed vessel 3 and letting electrolyte penetrate into the wound electrode 4 sufficiently. SOLUTION: In the cylindrical secondary battery, the electrode constituted by providing a separator 42 containing electrolyte between a positive pole 41 and a negative pole 43 and laminating them in layers is stored inside the sealed vessel 3. The positive pole 41 and the negative pole 43 are constituted by coating an active material on the surfaces of respective core bodies, and a plurality of netlike pieces 61 are nipped between opposing faces of each electrode of the positive pole 41 and the negative pole 43 and the separator 42.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylindrical secondary battery in which an electrode body serving as a power generation element is housed in a cylindrical airtight container and electric power generated by the electrode body can be taken out. Things.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 11, this type of secondary battery has a cylindrical closed container (3) formed by welding lids (2) to both ends of a cylindrical body (1). The winding electrode body (9) is housed inside. A pair of positive and negative electrode terminal mechanisms (5) are attached to the lid (2).
(9) and the electrode terminal mechanism (5) consist of the current collector (32) and the lead (3).
The power generated by the winding electrode body (9), which is connected to each other by (3), can be taken out from the pair of electrode terminal mechanisms (5). The lid (2) is provided with a pressure opening / closing gas discharge valve (7).

[0003] The winding electrode body (9) is shown in Figs.
As shown in the figure, a strip-shaped positive electrode (41) and a negative electrode (43) are superposed so as to be shifted in the width direction via a separator (42), and are wound in a spiral shape. Thereby, at one end of the two ends in the winding axis direction of the winding electrode body (9), the edge of the positive electrode (41) projects outward from the edge of the separator (42), At the other end, the separator (42)
The edge of the negative electrode (43) protrudes outward from the edge of the negative electrode (43).
In addition, since the winding electrode body (9) is wound under tension, the positive electrode (41), the separator (42) and the negative electrode (43) are in close contact with each other in the overlapping portion. .

The positive electrode (41) is a core made of aluminum foil.
(45) is formed by coating the positive electrode active material (44) on the surface,
(43) is a negative electrode active material (46) on the surface of the core (47) made of copper foil
Is applied.

The wound electrode body (9) in the closed container (3) is immersed in the electrolyte, and most of the electrolyte is separated by the separator (4).
2) has penetrated. The electrolyte is a solution obtained by dissolving the electrolyte in a solvent.
The electrolytic solution injected into the inside of the positive electrode (41), the separator (42) and the negative electrode (43) penetrate from the end surface (48) of the winding electrode body (9) in which the edges appear in a spiral shape, Permeates the separator (42).

The electrolyte serves as a charge transfer medium between the opposing surfaces of the positive electrode (41) and the negative electrode (43), and the electrolyte sufficiently penetrates the separator (42) sandwiched between the opposing surfaces. If
Since the movement of the charges is uniform throughout the separator (42), the battery output is stabilized. On the other hand, when the penetration of the electrolyte is insufficient, the movement of the charge becomes uneven, and the battery output becomes unstable.

Therefore, after injecting the electrolyte into the closed container, the inside of the closed container is pressurized to promote the penetration of the electrolyte. Further, in order to sufficiently infiltrate the electrolyte into the separator, an electrode body using a separator having a roughened surface (Japanese Patent Application Laid-Open No. 6-333550) or a method of heating the electrolyte and the electrode body (Japanese Patent Application Laid-Open No. 10-284121) ) Etc. have been proposed.

[0008]

However, since the positive electrode (41), the separator (42) and the negative electrode (43) are in close contact with each other on the end face (48) of the winding electrode body (9) without any gap. In addition, the electrolyte hardly permeated into the separator (42), and it took a long time to permeate the entire separator (42). Even in a battery using a separator having a roughened surface, the penetration time cannot be significantly reduced in order to utilize the capillary phenomenon of fine grooves formed on the surface of the separator,
Also, since fine groove processing is required on the separator surface,
There was a problem that the manufacturing process became complicated. Also, in the method of heating the electrolyte and the electrode body, although the viscosity of the electrolyte is reduced and the fluidity is improved, the positive electrode, the separator, and the negative electrode are in close contact with each other at the end surface of the wound electrode body without any gap. However, the infiltration difficulty was not improved, and the electrolyte did not sufficiently permeate the separator. In addition, the heating may cause evaporation of a low-boiling substance in the electrolyte, which may change the composition of the electrolyte.

In particular, in a high-capacity large-sized battery, since the electrode body becomes large, it takes time for the electrolyte to permeate.
There was a problem that unevenness in the permeation state occurred and sufficient battery characteristics could not be obtained.

An object of the present invention is to provide a cylindrical secondary battery having a structure in which an electrolyte can sufficiently penetrate a separator even when an electrode body having a separator interposed between a positive electrode and a negative electrode becomes large. Is provided.

[0011]

Means for Solving the Problems In a cylindrical secondary battery according to the present invention, an electrode in which a separator containing an electrolytic solution is interposed between a positive electrode and a negative electrode inside a cylindrical airtight container, and these are laminated. The body is housed, and the positive electrode and the negative electrode are each formed by applying an active material to the surface of the core body, and the electric power generated by the electrode body can be taken out from the pair of electrode terminals. Here, one or a plurality of spacer pieces are sandwiched between the facing surfaces of at least one of the positive electrode and the negative electrode of the electrode body and the separator.

In the cylindrical secondary battery according to the present invention, since the spacer piece forms a gap between the electrode and the separator, the electrolyte easily enters the gap. Further, the electrolyte gradually penetrates the separator.

In a specific configuration, the spacer pieces are net-like pieces.

In this specific configuration, since the mesh piece itself can pass the electrolytic solution, there is no possibility that the mesh piece hinders the charge transfer between the electrodes. As a result, the output of the battery is stabilized.

In a more specific configuration, the electrode body is a wound electrode body wound in a spiral shape with a separator interposed between a strip-shaped positive electrode and a strip-shaped negative electrode. here,
The net-like pieces are arranged at both ends or one end in the winding axis direction of the electrode constituting the winding electrode body, and extend over the entire length in the longitudinal direction orthogonal to the winding axis of the electrode.

According to this specific configuration, the net-like piece forms a gap at the end of the wound electrode body over the entire length in the longitudinal direction, so that the electrolyte easily penetrates into the gap, and furthermore, It gradually penetrates into the separator from around the gap. In addition, since the infiltration point of the electrolytic solution extends over the entire length in the longitudinal direction, the electrolytic solution uniformly permeates the entire separator in a short time.

In another specific configuration, the mesh pieces are arranged at a plurality of locations at intervals in a longitudinal direction perpendicular to the winding axis of the electrode constituting the winding electrode body, and have a width in the winding axis direction of the electrode. It has a width slightly shorter than that.

[0018] According to this specific configuration, since the mesh-like pieces form gaps penetrating in the winding axis direction at intervals in the longitudinal direction, the electrolyte easily penetrates into the gaps, and is further adjacent to the gaps. To the separator region sandwiched between the gaps. As a result, the electrolyte uniformly permeates the entire separator in a short time.

In still another specific configuration, the mesh piece comprises
The electrode constituting the winding electrode body is disposed at a plurality of positions at both ends or one end of the electrode in the winding axis direction at intervals in a longitudinal direction orthogonal to the winding axis of the electrode.

According to this specific configuration, since the net-like piece forms a gap at an interval at the end, the electrolytic solution easily penetrates into the gap and further permeates the separator from around the gap. . In addition, since a large number of places where the electrolytic solution enters are formed, the electrolytic solution uniformly permeates the entire separator in a short time.

The mesh piece is formed of a metal selected from aluminum, copper and nickel or an alloy thereof.

In this specific configuration, the reticulated piece formed of the metal or its alloy has excellent chemical stability in the electrolytic solution, and thus is not likely to be deteriorated in the closed container.
For example, as the metal forming the mesh piece sandwiched between the positive electrode and the separator, aluminum or an alloy thereof is preferable,
The metal forming the mesh piece sandwiched between the negative electrode and the separator is preferably a metal selected from copper or nickel or an alloy thereof. These are generally used as a material of a positive electrode current collector or a negative electrode current collector, and have excellent conductivity and stability in an electrolytic solution.

Further, the mesh piece is formed of a resin selected from a fluororesin, a polyethylene resin, a polypropylene resin, and a silicone resin. In the specific configuration,
Since the resin forming the net-like piece has excellent chemical stability in the electrolytic solution, there is no possibility that the net-like piece is deteriorated in the closed container.

[0024]

According to the cylindrical secondary battery of the present invention, even when the electrode body is large, the electrolyte sufficiently penetrates the entire separator, so that a stable battery output can be obtained.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment in which the present invention is applied to a cylindrical lithium ion secondary battery will be specifically described with reference to the drawings.

As shown in FIGS. 1 and 2, the cylindrical lithium ion secondary battery of this embodiment has lids at both ends of a cylindrical body (1).
(2) A wound electrode body (4) is accommodated in a cylindrical hermetic container (3) formed by welding and fixing (2). A pair of positive and negative electrode terminal mechanisms (5) and (5) are attached to the lid (2), and the winding electrode body (4) and each electrode terminal mechanism are attached.
(5) are connected to each other by a current collecting plate (32) and a lead portion (33), and the electric power generated by the winding electrode body (4) is output from the pair of electrode terminal mechanisms (5) and (5) to the outside. It is possible to take it out. The lid (2) has a pressure-opening / closing gas discharge valve.
(7) is attached.

As shown in FIG. 3, the wound electrode body (4)
Each of the strip-shaped positive electrode (41), separator (42), negative electrode (43),
And a net-like piece (61). The positive electrode (41) is a core
(45) is formed by coating the positive electrode active material (44) on the surface,
(43) is configured by applying a negative electrode active material (46) to the surface of a core (47). The net-like piece (61) is formed by knitting a wire rod, and is disposed at both ends in the winding axis direction of the winding electrode body (4), and is orthogonal to the winding axis in the longitudinal direction of the winding electrode body (4). Extends over the entire length of The mesh piece (61) arranged at a position in contact with the positive electrode (41) is made of aluminum, which is the same material as the core (45) of the positive electrode (41), and is meshed at a position in contact with the negative electrode (43). The piece (61) is formed of copper or nickel, which is the same material as the core (47) of the negative electrode (43).

Each of the positive electrode (41) and the negative electrode (43) is overlapped with being shifted in the width direction while being sandwiched between the separator (42) and the mesh piece (61), and wound in a spiral shape. I have. FIG. 7 shows a cross section of the end surface (48) of the wound electrode body (4) shown in FIG. At both ends in the axial direction of the winding electrode body (4), the positive electrode (4
The edge of 1) protrudes outward from the edge of the separator (42), and at the other end, the edge of the negative electrode (43) extends outward from the edge of the separator (42). It will protrude. The mesh piece (61) is arranged inside the edge of the separator (42).

The battery of the present invention is manufactured as follows. First, after the wound electrode body (4) shown in FIG. 3 is manufactured, the current collector plate (32) is joined to each end face (48) of the wound electrode body (4) by welding. Next, as shown in FIG. 2, the current collector plate (32) is connected to the electrode terminal mechanism (5) attached to the lid (2) via the lead portion (33). Thereafter, the take-up electrode body (4) is accommodated inside the cylinder (1), and the lid (2) is fixed by welding to the opening of the cylinder (1). Finally, an electrolytic solution is injected into the closed container (3) from a liquid injection hole (not shown) to complete the battery of the present invention.

As shown in FIG. 7, the net-like piece (61) extends over the entire length in the longitudinal direction at both ends of the wound electrode body (4).
A gap is formed between each of the positive electrode (41) and the negative electrode (43) and the separator (42). Therefore, in the battery assembling process, the electrolytic solution easily penetrates into the gap along the net-like piece (61) and gradually penetrates into the separator (42) from around the gap.
Furthermore, since the infiltration point of the electrolytic solution extends over the entire length in the longitudinal direction, the electrolytic solution permeates from both ends of the separator (42) toward the central portion, and the electrolytic solution is separated from the separator (42) in a short time. Penetrates uniformly throughout.

FIG. 4 shows another arrangement of the mesh piece (61) in the winding electrode body (4), and FIG. 8 shows an end surface of the winding electrode body (4) shown in FIG. (48) C-
It shows a cross section along the line C. The net-like piece (61) is arranged at an interval in a direction perpendicular to the winding axis of the winding electrode body (4), and is formed to have a width slightly shorter than the width in the longitudinal direction of the winding electrode body (4). ing.

As shown in FIG. 8, the net-like pieces (61) form gaps penetrating in the winding axis direction at intervals in the longitudinal direction. The electrolyte easily penetrates into the gap, and penetrates in both directions into the region of the separator (42) sandwiched between the gaps adjacent in the longitudinal direction. As a result, the electrolyte uniformly permeates the entire separator (42) in a short time.
Further, since the mesh piece (61) is formed to have a width slightly shorter than the width in the longitudinal direction of the winding electrode body (4), the end of the mesh piece (61) is formed at both ends of the separator (42). It does not protrude further outward, thereby preventing a short circuit between the positive electrode (41) and the negative electrode (43).

FIG. 5 shows still another arrangement of the mesh pieces (61) in the winding electrode body (4). FIG. 9 shows the arrangement of the winding electrode body (4) shown in FIG. It shows a cross section of the end face (48) along the line CC. The mesh piece (61) is provided at both ends in the winding axis direction of the winding electrode body (4) at intervals in the longitudinal direction orthogonal to the winding axis of the winding electrode body (4), and the positive electrode (41) and the positive electrode (41). The plurality of anodes (43) are disposed at a plurality of locations on the interface between the separator (42). Here, the plurality of mesh pieces (61) are arranged so that they do not overlap each other on the front and back surfaces of the positive electrode (41) and the negative electrode (43), and do not overlap each other even in the longitudinal direction of the wound electrode body (4). I have.

As shown in FIG. 9, the net-like piece (61) forms a gap at an interval at the end, so that the electrolyte easily penetrates into the gap and further separates the separator (42) from the periphery of the gap. ). Further, by forming a plurality of places where the electrolyte enters, the electrolyte uniformly permeates the entire separator (42) in a short time. Since the plurality of mesh pieces (61) have the above-described arrangement, the winding electrode body depends on the thickness of the mesh pieces (61).
(4) An increase in the outer diameter can be minimized.

It should be noted that the above-mentioned wire net is made of a metal mesh piece (6
Instead of 1), a net-like piece (62) made of a resin sheet having a large number of through holes as shown in FIG. 10 can be used.

[0036]Experiment Preparation of positive electrode  LiCoO as positive electrode active material₂And charcoal as a conductive agent
And a mixture thereof at a weight ratio of 90: 5 to prepare a positive electrode mixture. Next
In addition, polyvinylidene fluoride as a binder is N-methyl-
Dissolve in 2-pyrrolidone (NMP) to prepare NMP solution
Was. And the weight ratio between the positive electrode mixture and polyvinylidene fluoride is
Mix the positive electrode mixture and the NMP solution so that the ratio becomes 95: 5.
Thus, a slurry was prepared. This slurry is used as a positive electrode core.
Doctor blade method on both sides of aluminum foil
Apply and vacuum dry at 150 ° C for 2 hours to produce positive electrode
Made.

[0037]Fabrication of negative electrode  Dissolve polyvinylidene fluoride as a binder in NMP
An NMP solution was prepared. Next, graphite powder (particle diameter 10μ)
m) and polyvinylidene fluoride in a weight ratio of 85:15.
To prepare a slurry. This slurry
The doctor blade method is applied to both sides of the copper foil as the negative electrode core.
And vacuum dried at 150 ° C for 2 hours to form a negative electrode.
Produced.

[0038]Preparation of electrolyte  Ethylene carbonate and diethyl carbonate as solvents
Are mixed at a volume ratio of 1: 1, and LiPF₆1m
The solution was dissolved at a ratio of ole / l to prepare an electrolytic solution.

[0039]Fabrication of the wound electrode body  The mesh pieces used in the following Examples 1 to 6 were all
Is the mesh 330. Examples 1 to 3
6 and the winding length of the winding electrode body used in the comparative example
Are 4 m each, and the cell sandwiched between the positive and negative electrodes
The parator uses a polyethylene-permeable microporous membrane made of polyethylene.
Using.

[0040]Example 1  10 nets made of aluminum between the positive electrode and the separator
Pieces (30 × 50 mm, thickness 100 μm)
As shown in FIG. Those
Is wound up by overlapping with the negative electrode through the separator,
A wound electrode body was produced.Example 2  Between the negative electrode and the separator, ten copper mesh pieces (30 ×
(50mm, thickness 100μm) so that they do not overlap each other
They were arranged at equal intervals in the strip length direction. Separe them
And roll it over with the positive electrode
A polar body was prepared.Example 3  Example 2 except that the net-like piece was made of nickel.
Similarly, a wound electrode body was manufactured.Example 4  10 mesh pieces made of PTFE between the positive electrode and the separator
(20 × 50mm, thickness 100μm) do not overlap each other
In the same manner, they were arranged at equal intervals in the winding length direction. Those,
Laminated with negative electrode via separator, winding
An electrode body was prepared.Example 5  Ten nets made of polyethylene between negative electrode and separator
Pieces (20 × 50 mm, thickness 100 μm)
As shown in FIG. Those
Is wound up by overlapping with the positive electrode through the separator,
A wound electrode body was produced.Example 6  Except that the mesh was made of polypropylene,
A wound electrode body was produced in the same manner as in Example 5.Comparative example  Positive and negative electrodes are superimposed via a separator and wound
Thus, a wound electrode body having no net-like piece was produced.

[0041]Battery assembly  As shown in FIG. 2, current collector plates are provided at both ends of the wound electrode body (4).
(32) is welded. Furthermore, the current collector (32) is connected to the lead (3
Electrode terminal machine attached to lid (2) via 3)
It is joined with the structure (5). This is inserted into the cylinder (1) and the lid
After welding (2) to the cylinder (1), the electrolytic solution is placed in the closed container (3).
Was injected to assemble the battery of the present invention. In addition, in FIG.
The cylindrical body (1) is made of aluminum and has an outer diameter of 45 m.
m, height 200 mm and thickness 1.25 mm.
The lid (2) is made of aluminum and has a diameter of 45 mm and a thickness of 45 mm.
5 mm. The completed battery has an outer diameter of 4
5mm, total length including both electrode terminal mechanism (5) (5) is 220
mm.

[0042]Test 1  The electrolyte content of each battery was measured. In testing,
After injecting 20 g of electrolyte into the closed container,
Repeat the operation of reducing the pressure to 00 mmHg and leaving it to stand for 30 minutes.
did. The liquid content is such that the electrolyte cannot be poured into the closed container.
The total injection volume until the injection was completed. Table 1 shows the results.

[0043]

【table 1】

[0044]Test 2  Next, the output density of each battery was measured. In the test,
DOD 80%, 25A, 15A, 5A
The battery voltage when each battery was discharged for 30 seconds was measured. So
Then, the current value at 2.7 V from the current-voltage (IV) straight line is
Then, the output density was calculated from the battery weight. as a result
Are shown in Table 2.

[0045]

[Table 2]

From the results of Tests 1 and 2, it can be seen that all of the batteries of the examples have a large electrolyte content and a high output density. Therefore, according to the present invention, it is clear that the penetration of the electrolytic solution into the electrode body is promoted by the formation of the gap by the mesh-like pieces, and the electrolytic solution sufficiently penetrates into the separator.

The configuration of each part of the present invention is not limited to the above-described embodiment, but can be widely applied to a battery as a power generation element by impregnating an electrode body with an electrolytic solution, and within the technical scope described in the claims. Various modifications are possible.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an appearance of a battery of the present invention.

FIG. 2 is a cross-sectional view illustrating a current collecting structure of the present invention.

FIG. 3 is a partially developed view of the wound electrode body of the present invention.

FIG. 4 is a partially developed view of another winding electrode body.

FIG. 5 is a partially developed view of still another wound electrode body.

FIG. 6 is a plan view showing a part of the wound electrode body of the present invention.

FIG. 7 is an enlarged sectional view showing a main part of a wound electrode body of the present invention.

FIG. 8 is an enlarged sectional view showing a main part of another winding electrode body.

FIG. 9 is an enlarged sectional view showing a main part of still another wound electrode body.

FIG. 10 is a front view showing another example of the mesh piece used in the present invention.

FIG. 11 is a cross-sectional view illustrating a conventional current collecting structure.

FIG. 12 is a partially developed view of a conventional wound electrode body.

FIG. 13 is an enlarged sectional view showing a main part of a conventional wound electrode body.

FIG. 14 is a partial cross-sectional view of a conventional wound electrode body.

[Explanation of symbols]

 (3) Closed container (32) Current collector plate (4) Winding electrode body (41) Positive electrode (42) Separator (43) Negative electrode (5) Electrode terminal mechanism (61) Mesh piece (9) Winding electrode body

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Atsuhiro Funabashi 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Toshiyuki Noma 2-chome Keihanhondori, Moriguchi-shi, Osaka No. 5-5 Sanyo Electric Co., Ltd. (72) Inventor Ikuo Yonezu 2-5-5 Keihanhondori, Moriguchi-shi, Osaka F-term in Sanyo Electric Co., Ltd. 5H028 AA08 BB07 CC08 CC13 EE01 EE06 5H029 AJ14 AK03 AL07 AM03 AM05 AM07 BJ02 BJ14 CJ07 CJ28 DJ04 DJ11 EJ01 EJ12

Claims (8)

[Claims] An electrode body in which a separator containing an electrolytic solution is interposed between a positive electrode and a negative electrode is housed inside a cylindrical closed container, and the positive electrode and the negative electrode are each activated on the surface of a core. In a cylindrical secondary battery that is formed by applying a substance and can take out the electric power generated by the electrode body from a pair of electrode terminals, at least one of the positive electrode and the negative electrode of the electrode body A cylindrical secondary battery, wherein one or more spacer pieces are sandwiched between surfaces facing the separator. 2. The spacer piece is a net-like piece.
4. The cylindrical secondary battery according to 4. 3. The cylindrical secondary battery according to claim 2, wherein the electrode body is a spirally wound electrode body with a separator interposed between a strip-shaped positive electrode and a strip-shaped negative electrode. 4. A reticulated piece is disposed at both ends or one end in the winding axis direction of an electrode constituting a winding electrode body, and extends over the entire length in a longitudinal direction orthogonal to the winding axis of the electrode. The cylindrical secondary battery according to claim 3. 5. The net-like piece is disposed at a plurality of positions at intervals in a longitudinal direction orthogonal to the winding axis of the electrode constituting the winding electrode body, and is slightly shorter than the width of the electrode in the winding axis direction. The cylindrical secondary battery according to claim 3 having a width. 6. The reticulated piece is provided at a plurality of locations at both ends or one end in the winding axis direction of the electrode constituting the winding electrode body, at intervals in the longitudinal direction orthogonal to the winding axis of the electrode. The cylindrical secondary battery according to claim 3, which is disposed. 7. The cylindrical secondary battery according to claim 2, wherein the mesh piece is formed of a metal selected from aluminum, copper, and nickel or an alloy thereof. 8. The cylindrical secondary battery according to claim 2, wherein the mesh piece is formed of a resin selected from a fluororesin, a polyethylene resin, a polypropylene resin, and a silicone resin.