JP3484422B2 - Battery and method for manufacturing battery - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery having an electrode pair in which a separator is sandwiched between a pair of electrodes and a method for manufacturing the battery.

[0002]

2. Description of the Related Art In a battery such as a lithium battery, which has a low conductivity of an electrolytic solution, or a battery such as a nickel-cadmium battery, which extracts a large current, it is necessary to increase the electrode area. Therefore, in such a battery,
The main portion of the battery is formed by folding a belt-shaped battery electrode device (electrode pair) in which positive electrode side electrodes and negative electrode side electrodes are superposed via a separator by 180 degrees, or folding them in a spiral shape. Are formed.

FIG. 12 shows a cross section of a folding type lithium secondary battery described in, for example, Japanese Patent Application No. 5-076840. In this lithium secondary battery, a battery electrode device, which is a strip-shaped electrode pair 4 formed by forming a positive electrode 2 and a negative electrode 3 on the surface of a porous separator 1, is provided in 180 degree increments. The main part of the battery is formed by folding it into a certain size while changing its direction. In addition, 5 is an insulating seal material, and 6 is a conductive plate material for extracting electric power.

In the folding type lithium secondary battery shown in FIG. 12, a tensile force or a compressive force is applied to the folded portion 4a of the electrode pair 4, so that the active material layers of the electrodes 2 and 3 are likely to crack. Therefore, for example, Japanese Patent Application No. 5-0768
In No. 40, a flexible fluororesin is used as a binder for fixing the active materials of the electrodes 2 and 3 to give flexibility to the active material layers of the electrodes 2 and 3, so that the electrodes 2 and 3 in the folded portion 4a are covered. It is described that cracking is prevented.

[0005]

However, there is a limit to the kinds of binders that give flexibility to the active material layers of the electrodes 2 and 3 and prevent the electrodes 2 and 3 from cracking in the folded portion 4a. That is, depending on the type of the active material, such a binder does not have a good compatibility at the time of mixing with the active material powder, and therefore a binder that gives sufficient flexibility to the active material layer cannot be used, resulting in poor flexibility. There was a problem that there was a case where the binder had to be used. Therefore, in such a case, there is a problem in that the folded portion 4a of the electrode pair 4 of the lithium secondary battery causes an inconvenient crack. The above problem similarly occurs in a battery in which the strip-shaped electrode pair 4 is wound in a spiral shape.

Although forming the active material layer directly on the separator is a fundamental method for solving the problem of relative displacement between the positive electrode, the negative electrode and the separator, the active material species of the active material layer and the binder are formed. Depending on the species, the adhesiveness to the separator may be poor, and thus the intended function may not be exhibited.

Furthermore, the thickness of the electrode is limited not only by its performance but also by the design of the entire battery. For example, the thickness is limited for use in an ultrathin sheet battery, but if the active material is overfilled to a certain thickness, the maximum current performance of the electrode may be impaired.

The present invention has been made in order to solve the above problems, and the performance can be maintained without causing the battery and the electrode and the separator from being displaced from each other, in which the electrode is not cracked or peeled off during bending or winding. It is an object to provide a battery and a method for manufacturing such a battery.

[0009]

(1) A battery of the present invention has a first active material layer and a current collector which are in close contact with each other.
And a second electrode, a separator sandwiched between the first electrode and the second electrode, and an electrolyte, and the active material layer of at least one of the first and second electrodes and the separator are polymers. It is characterized by being bonded by an electrolyte layer to form an electrode pair.

(2) In the contact area of the active material layer with the separator, the value of the ratio of the area of the non-bonded portion to the area of the bonded portion of the polymer electrolyte layer is r, and the ionic conductivity of the polymer electrolyte layer is The value of the ratio of the thickness of the polymer electrolyte layer to Tp was defined as Tp, and the value of the ratio of the effective thickness of the separator taking into consideration the bending ratio of the electrolyte used in this battery with respect to the ionic conductivity was defined as Tq. In this case, it is preferable that the relationship 0.9 <r × (Tp / Tq + 1) <1.1 holds. (3) The anion or cation of the electrolyte salt contained in the polymer electrolyte layer may be the same as the anion or cation of the electrolyte salt forming the active material layer. (4) Further, it is preferable that the separator joined by the polymer electrolyte layer and at least one of the first electrode and the second electrode are wound. (5) Further, the electrolytic solution may be composed of a lithium salt and an aprotic organic solvent. (6) Further, the aprotic organic solvent may contain ethylene carbonate. (7) Furthermore, the method for producing a battery of the present invention comprises a step of forming a positive electrode by bringing the positive electrode active material layer and the positive electrode current collector into close contact with each other,
A step of forming a negative electrode by bringing the negative electrode active material layer and the negative electrode current collector into close contact with each other, and a step of forming a pair of electrodes by adhering at least one of the positive electrode and the negative electrode and the separator by the polymer electrolyte layer. There is. (8) Further, it is preferable to include a step of injecting an electrolytic solution after the step of adhering at least one of the positive electrode and the negative electrode to the separator with the polymer electrolyte layer and forming the electrode pair.

[0011]

[0012]

1 is a side view showing an electrode pair for a lithium secondary battery, which is an example of an electrode device, as a reference example for explaining the battery of the present invention, and FIG. 2 shows the electrode device for a battery. It is a side view which shows the state which bent and formed the bending part.
In the figure, 10 is a positive electrode current collector, and 11 is a positive electrode current collector 10.
A positive electrode active material layer having a constant thickness d1 (eg, d1 = 200 μm) formed thereon, 12 is a strip-shaped first electrode composed of a positive electrode current collector 10 and a positive electrode active material layer 11, and a positive electrode side electrode , 13 is a negative electrode current collector, 14 is a negative electrode active material layer formed on the negative electrode current collector 13 with a constant thickness d2 (for example, d2 = 200 μm), and 15 is a negative electrode current collector 13 and a negative electrode active material layer 14. And a negative electrode that is a strip-shaped second electrode composed of
Is a thin strip-shaped separator, 17 is a strip-shaped battery electrode device (electrode) formed by sandwiching the separator 16 between the positive electrode active material layer 11 side of the positive electrode side electrode 12 and the negative electrode active material layer 14 side of the negative electrode side electrode 15. Pair). In addition, 17a is an electrode pair 1
It is a bent portion of 7.

Reference numeral 20 is a depth that reaches the positive electrode current collector 10 and fills the width of the positive electrode active material layer 11 (vertical direction in the plane of the drawing of FIG. 1) for folding the positive electrode active material layer 11. It is an electrode bending groove. The electrode bent groove 20 has an opening-side groove width of 400 μm and is formed such that the groove interval between them is twice the thickness d2 of the negative electrode active material layer 14 (200 × 2 = 400 μm). The first groove 20a and the second groove 20b having an angle of about 90 degrees and the second groove 2 having the opening-side groove width of 100 μm
It is composed of three types of grooves, namely, a third groove 20c formed so that the groove interval between the groove 0b and 0b is 9.9 cm, for example. The positive electrode active material layer 11 has these three types of electrode bending grooves 2
0 is repeatedly formed.

Reference numeral 21 is a depth reaching the negative electrode current collector 13 and the width of the negative electrode active material layer 14 is as large as possible.
4 is an electrode bending groove formed in FIG. This electrode bent groove 21
Are arranged on both sides of the third groove 20c of the positive electrode 12,
The first groove 2 having an opening angle of about 90 degrees and having an opening-side groove width of 400 μm and a groove interval between them is twice the thickness d1 of the positive electrode active material layer 11 (200 × 2 = 400 μm).
1a and the second groove 21b, and the opening side groove width is 100 μm
Then, the positive electrode 12 is composed of three types of grooves, that is, a third groove 21c arranged at an intermediate position between the first groove 20a and the second groove 20b. The negative electrode active material layer 14 has this 3
The kind of electrode bending groove 21 is repeatedly formed.

As described above, the battery electrode device according to the first embodiment has the active material layer 11 and the current collector 10 in close contact with each other.
Of the first electrode 12, the separator 16 provided in contact with the active material layer 11 of the first electrode 12, the active material layer 14 and the current collector 13 in close contact with each other. A second electrode 15 in contact with the separator 16, and the active material layer 11 of the first and second electrodes 12 and 15,
14 includes electrode bent grooves 20 and 21.

Next, the procedure for forming the main part of the battery by folding the strip-shaped electrode pair 17 while changing its direction by 180 degrees will be described. For example, as shown in FIG. 2, the positive electrode 12 is on the outer side, the negative electrode 15 is on the inner side, the first and second grooves 20a and 20b and the third groove 21c are folds, and the electrode pair 17 is 180 degrees. Fold once. In this case, the positive electrode 12 of the bent portion 17a is folded without the tensile force and the compressive force acting on the positive electrode active material layer 11 with the first and second grooves 20a and 20b closed. . Further, the negative electrode 15 of the bent portion 17a has a third
The groove 21c is opened at an angle of about 180 degrees,
The negative electrode active material layer 14 is folded without exerting a tensile force or a compressive force. The separator 16 is bent along the outer surface of the negative electrode 15 while slipping between the positive electrode 12 and the negative electrode 15.

Similarly, with the positive electrode 12 as the inner side and the negative electrode 15 as the outer side, the first and second grooves 21a, 2 are formed.
The electrode pair 17 is folded 180 degrees to the opposite side to the above, with the fold line 1b and the third groove 20c. Also in this case, the electrode pair 17 is folded without applying a tensile force or a compressive force to the positive electrode and negative electrode active material layers 11 and 14 of the folded portion 17a. Thereafter, similarly, as shown in FIG. 12, this electrode pair 1
The main part of the battery is formed by folding 7 while changing its direction by 180 degrees.

Next, a specific method for manufacturing the lithium secondary battery will be described. First, how to make the positive electrode 12 that is the first electrode will be described. 87 wt% of LiCoO ₂ , graphite powder (KS- manufactured by LONZA)
6) 8 wt% of binder and 5 wt% of binder (polyvinylidene fluoride) adjusted positive electrode active material paste on the aluminum foil of 20 μm thickness which becomes the positive electrode current collector 10 and 300 μm thickness by doctor blade method. The active material layer is formed by coating while adjusting to 30.degree.
Leave for half a minute to dry. Next, the semi-dried active material layer is cut using a blade having a thickness of 400 μm and a blade having a thickness of 100 μm to form the electrode bent groove 20, which is then main dried at 150 ° C. for 1 hour. Next, the positive electrode active material layer is pressed to a thickness of 200 μm to complete the strip-shaped positive electrode side electrode 12 in which the positive electrode active material layer 11 of 200 μm is formed on the positive electrode current collector 10 of aluminum foil. . By the above press, the porosity of the positive electrode active material layer 11 is set within the range of 10 to 30%.

Next, the negative electrode 15 which is the second electrode
Explain how to make. 95% by weight of mesophase microbead carbon (made by Osaka Gas) and 5 binders
The negative electrode active material paste adjusted to wt% was used as the negative electrode current collector 1
3 on a strip-shaped copper foil with a thickness of 20 μm while adjusting the thickness to 300 μm by the doctor blade method to form an active material layer, which is then left in a dryer at 80 ° C. for 30 minutes. Make it semi-dry. Next, the semi-dried negative electrode active material layer was cut with a blade having a thickness of 400 μm and a blade having a thickness of 100 μm to form the electrode bending groove 21.
Main drying is performed at 50 ° C. for 1 hour. Next, the negative electrode active material layer is pressed to a thickness of 200 μm to complete the strip-shaped negative electrode side electrode 15 in which the negative electrode active material layer 14 of 200 μm is formed on the negative electrode current collector 13 of copper foil. . In addition, the porosity of the negative electrode active material layer 14 is 10 to 3 by the above press.
It is contained within the range of 0%.

Next, how to make a lithium secondary battery using the positive electrode 12 and the negative electrode 15 will be described. First, the strip-shaped electrode pair 1 is formed by sandwiching a strip-shaped polypropylene porous sheet (Cell Guard # 2400 manufactured by Daicel Chemical Industries) as the separator 16 between the positive electrode 12 and the negative electrode 15.
The battery electrode device of No. 7 is formed. In this case, for example, the third groove 21c of the negative electrode 15 is arranged between the first and second grooves 20a, 20b of the positive electrode 12, and the first and second grooves 21a, 21a of the negative electrode 15 are arranged. 21b
The third groove 20c of the positive electrode 12 is arranged in between. Subsequently, the electrode pair 17 is formed by connecting the electrode bending groove 20,
While turning 180 degrees at the position of 21, for example, 12
After being folded back and stacked, they are sandwiched between stainless steel current collector plates, and then an electrolytic solution containing ethylene carbonate and dimethoxyethane as a solvent and lithium perchlorate as an electrolyte is injected into the electrode pair 17. Then, the periphery of the electrode pair 17 and the like is fixed with polyethylene resin and sealed to complete the lithium secondary battery.

As described above, in this lithium secondary battery, since the predetermined electrode bent grooves 20 and 21 are formed in the positive electrode 12 and the negative electrode 15, the positive electrode current collector 10 is folded when the electrode pair 17 is folded. It does not cause an inconvenient crack in the negative electrode current collector 13. Further, in this lithium secondary battery, since the folding position is determined by the electrode bending grooves 20 and 21, the electrode pair 17 can be quickly folded. Although 1000 cells were continuously manufactured by the above-mentioned manufacturing method, none of the cells had an undesired crack in the electrode when the electrode pair 17 was folded. Note that, for example, the positive electrode 1
Even when only 2 is composed of the current collector and the active material layer in which the electrode bent groove 20 is formed and the negative electrode 15 is made of lithium metal, the same effect as above can be obtained.

Here, the porosity of the active material layers 11 and 14 is set to 1
0-30% means that when the porosity is lower than 10%,
This is because the maximum current performance of the battery is impaired and the performance of the battery is reduced, and when the porosity is increased above 30%, the output per volume of the battery is reduced.

In FIG. 3, one electrode bending groove 20, is provided on the electrodes 12, 15 arranged outside the bending portion 17a of the electrode pair 17.
It is explanatory drawing at the time of forming only 21. In this case, the shape of the electrode bent groove 20 of the electrode (for example, the positive electrode 12) arranged outside the bent portion 17a is such that the width of the current collector side groove is t.
1. If the opening side groove width is t2, it is necessary to satisfy the following conditions: t1 ≧ 2 × (d1 + d2) (1) t2 ≧ t1 (2)

For example, when t1 = t2 = 800 μm, no tensile force or compressive force is generated in the positive electrode active material layer 11 arranged outside the bent portion 17a when the electrode pair 17 is folded, and this positive electrode active material is not generated. No unfavorable cracks occur in the layer 11.
Similarly, in the case where the negative electrode 15 is arranged outside the bent portion 17a, the shape of the electrode bent groove 20 may satisfy the conditions of Expression (1) and Expression (2). In addition, the bent portion 17
The electrode bending grooves 20 and 21 of the electrodes arranged inside a are 1
There is no particular limitation on its shape.

FIG. 4 is an explanatory diagram in the case of forming a plurality (for example, n) of electrode bending grooves 20 and 21 in the electrodes 12 and 15 arranged outside the bent portion 17a of the electrode pair 17. In this case, the shape of the electrode bent groove 20 of the electrode (for example, the positive electrode 12) arranged on the outer side of the bent portion 17a is the width of the current collector side groove of the 1 to n electrode bent grooves 20. t11, t
12, ... t1n, opening side groove widths are t21, t2
2, ... t2n, t21 + t22 + ... + t2n ≧ 4d1 (3) 21 ≧ t11, t22 ≧ t12, ... And t2n ≧ t1n (4) Need to meet.

For example, as shown in FIG. 5, three electrode bending grooves 20a are provided on the positive electrode 12 at intervals of 200 μm,
20b and 20c are formed, t21 = 300 μm, t22
= 200 μm, t23 = 300 μm, t11 = t12 =
When t13 = 0, no tensile force or compressive force is generated in the positive electrode active material layer 11 arranged outside the bent portion 17a when the electrode pair 17 is folded, and this positive electrode active material layer 11 is undesirably cracked. Does not occur. In addition, the negative electrode 15 has a bent portion 17
The shape of the electrode bending groove 21 when it is arranged outside a is sufficient to satisfy the expressions (3) and (4). The electrode bending groove 20 of the electrode arranged inside the bent portion 17a,
There is only one 21, and there is no particular limitation on its shape.

FIG. 6 shows an electrode bending groove 2 for the electrodes 12 and 15 arranged outside the bent portion 17a of the electrode pair 17.
It is explanatory drawing of the formation range of 0 and 21. When a plurality of electrode bending grooves 20 are formed on the electrode (for example, the positive electrode 12) arranged outside the bending portion 17a, the electrode bending grooves 20 are formed.
The length L of the range that forms is required to satisfy the condition of L ≦ π × (d1 + d2) (5) where pi is π. As shown in FIG.
= Π × (d1 + d2) indicates a semicircular length when the end of the bent portion 17a has an arc shape, and the electrode bent groove 20 is formed within this length L. There is a need. The same applies to the case where the negative electrode 15 is arranged outside the bent portion 17a.

FIG. 7 shows an example in which the groove width of the electrode bent groove 20 of the positive electrode 12 and the groove width of the electrode bent groove 21 of the negative electrode 15 are different. The positive electrode active material layer 11 can hardly be deformed by compression after the final pressing, and the compression rate is 1. However, the negative electrode active material layer 14 using carbon
Can be compressed and deformed to a volume of 80 to 90% after the final pressing, and the compression rate is 0.8 to 0.9. Therefore, when the positive electrode 12 comes to the outside of the bent portion 17 a of the electrode pair 17, the first groove 20 of the positive electrode active material layer 11 is formed.
If the opening-side groove width of a and the second groove 20b is not 400 μm, the positive electrode active material layer is cracked by compression.

On the other hand, the negative electrode 1 is provided outside the bent portion 17a.
5, the negative electrode active material layer 14 is compressed and contracts even if the opening-side groove width of the first groove 21a and the second groove 21b of the negative electrode active material layer 14 is 350 μm. 14 does not crack. That is, when the active material layer is deformable by compression, the electrode bending groove 2 of the electrode
The groove width of 0, 21 may be smaller than the required width.

Embodiment 1. FIG. 8 is an exploded perspective view of an electrode pair of the lithium secondary battery of the battery according to the embodiment of the present invention. In the figure, 23 is formed on the positive electrode active material layer 11 of the positive electrode 12 and has, for example, a lattice size of 1.95 mm × 1.0 mm and a groove width of 0.4.
mm grid grooves 24 are formed in the negative electrode active material layer 14 of the negative electrode 15, for example, a grid size of 1.95 mm ×
It is a lattice-shaped groove having a groove width of 1.0 mm and a groove width of 0.4 mm.

Here, for the positive electrode 12, the positive electrode active material paste described in Example 1 was applied to a strip-shaped aluminum foil having a thickness of 20 μm by the doctor blade method so as to have a thickness of 300 μm, and then this was applied. It is left in a drier at 80 ° C. for 30 minutes to be in a semi-dried state, and then this semi-dried positive electrode active material paste is applied to this and a grid size of 1.95 mm ×
Expanded metal having a mesh width of 0.4 mm and a width of 1.0 mm was stacked and lightly pressed at 2 Kg / cm 2 to form grid-like grooves 23 in the positive electrode active material paste, and then the grid-shaped grooves 23 were formed at 150
This is completed by carrying out main drying at 1 ° C. for 1 hour and then pressing this positive electrode active material layer to a thickness of 200 μm (porosity 10 to 30%).

The negative electrode 15 is shown in FIGS.
The thickness of the negative electrode active material paste described in connection with
After applying the doctor blade method to the thickness of 300 μm on the copper foil, the product is left in a dryer at 80 ° C for 30 minutes to be in a semi-dried state, and then the negative electrode active material in the semi-dried state is used. Material paste, grid size 1.95mm
Expanded metal having a mesh width of 0.4 mm and a wire width of 0.4 mm was overlaid and lightly pressed at 2 Kg / cm 2 to form grid-like grooves 24 in this negative electrode active material paste, and then this was applied to 15
This is completed by performing main drying at 0 ° C. for 1 hour and then pressing this negative electrode active material layer so that the thickness becomes 200 μm (porosity 10 to 30%).

Next, with reference to FIG. 9 and FIG. 10, a method of making a winding type lithium secondary battery using the positive electrode 12 and the negative electrode 15 will be described. Example 1
The strip-shaped polypropylene porous sheet (separator 16) described in 1. is sandwiched between the positive electrode active material layer 11 side of the positive electrode side electrode 12 and the negative electrode active material layer 14 side of the negative electrode side electrode 15, and the strip shaped electrode pair 17 is sandwiched. To form. Then, as shown in FIG. 9, the electrode pair 17 has the negative electrode side electrode 15 inside and the negative electrode current collecting tab 15 inside the folding side.
Fold it in half with a attached. Then, with the positive electrode collector tab 12a attached to one end side of the folded electrode pair 17, as shown in FIG. 10, this is wound around the bobbin 18 and then inserted into the stainless steel can 19. Next, after joining the positive electrode current collecting tab 12a and the positive electrode terminal, an electrolytic solution containing ethylene carbonate and dimethoxyethane as a solvent and a lithium perchlorate salt as an electrolyte is injected into the inside of the positive electrode current collector tab 12a, and a sealing treatment is performed to wind it up. A type of lithium secondary battery is completed.

As described above, in this lithium secondary battery, since the predetermined grid-like grooves 23 and 24 are formed in the entire active material layers 11 and 14 of the positive electrode 12 and the negative electrode 15, the electrode pair 17 is attached to the bobbin 18. When rolled up, the positive electrode side electrode 12 and the negative electrode side electrode 15 are bent along the grid-like grooves 23 and 24, so that no undesired cracking occurs in the positive electrode active material layer 11 and the negative electrode active material layer 14. Although 1000 cells were continuously manufactured by the above manufacturing method, none of the electrodes had an undesired crack when the electrode pair 17 was wound up. Note that, for example, the positive electrode 1
Even if only 2 is composed of the current collector and the active material layer in which the grid-like grooves 24 are formed and the negative electrode 15 is made of lithium metal, the same effect as above can be obtained.

Here, if the size of the grid-like grooves 23, 24 is properly adjusted by changing the grid size or the mesh width of the expanded metal, the positive electrode 12 or the electrode 12 having the grid-like grooves 23, 24 formed therein can be adjusted. By using the electrode pair 17 having the negative electrode 15, the folding type lithium secondary battery as shown in Example 1 can be easily manufactured without causing any inconvenient cracking.

Further, the negative electrode active material layer 14 of the negative electrode 15
Has a compressibility of 0.8 to 0.9, the groove width of the grid-like grooves 24 of the negative electrode active material layer 14 may be set to about 0.35 mm in the above embodiment.

Further, the positive electrode 12 and the negative electrode 15
May be manufactured as follows. First, a positive electrode active material paste (negative electrode active material paste) is applied to a strip-shaped aluminum foil (copper foil) having a thickness of 20 μm by, for example, a doctor blade method so as to have a thickness of 200 μm.
Leave it in the oven at 30 ° C for 30 minutes to become semi-dry. Next, this semi-dried positive electrode active material paste was applied to this with a grid size of 1.95 mm × 1.0 mm and a screen wire width of 0.4 m.
m expanded metal layers are stacked and lightly pressed at 2 Kg / cm2 to form grid-like grooves 23 and 24 in this positive electrode active material paste (negative electrode active material paste), and then this is subjected to 15
Main dry for 1 hour at 0 ° C. Then, the positive electrode active material layer (negative electrode active material layer) is pressed at, for example, 2 t / cm 2 to manufacture the positive electrode side electrode 12 (negative electrode side electrode 15). In this case also, the positive electrode active material layer 11 (negative electrode active material layer 1
The porosity of 4) is within the range of 10 to 30%.

Embodiment 2. A method of manufacturing a battery electrode according to still another embodiment of the present invention will be described with reference to FIGS. 8, 9 and 10. The structure of the electrodes is the same as that described in the first embodiment.

First, how to make the positive electrode 12 will be described. The positive electrode active material paste described in Embodiment 1 was applied on a strip-shaped aluminum foil having a thickness of 20 μm by a doctor blade method so as to have a thickness of 200 μm, and the paste was applied at 80 ° C.
Leave it in the dryer for 2 hours to fully dry, and drive off the solvent in the paste completely. Next, this dried positive electrode active material layer was applied to this with a lattice size of 1.95 mm × 1.0 mm.
Then, the positive electrode active material layer is pressed with a pressure of 2 t / cm @ 2 in a state where the expanded metal having a net wire width of 0.4 mm is stacked to manufacture the positive electrode 12 having a porosity of 10 to 30%.

Next, how to make the negative electrode 15 will be described. The negative electrode active material paste described in Embodiment 1 was applied to a strip-shaped copper foil having a thickness of 20 μm by the doctor blade method so as to have a thickness of 200 μm, and then left in a dryer at 80 ° C. for 2 hours. Dry thoroughly and drive off the solvent in the paste completely. Then, the dried negative electrode active material layer was superposed with an expanded metal having a grid size of 1.95 mm × 1.0 mm and a mesh width of 0.4 mm, and the negative electrode active material layer was applied with a pressure of 2 t / cm 2. And the negative electrode 15 having a porosity of 10 to 30% is manufactured.

As described above, in this electrode manufacturing method,
After applying a paste containing the active material on the current collector, dry it sufficiently and then press it while applying a groove type expanded metal to the dried active material layer. Therefore, the electrode having the grid-like grooves can be manufactured in a short time. Specifically, the battery manufacturing time can be reduced by about 10%.

The positive electrode active material layer 11 and the negative electrode active material layer 1
In the case where the electrode bent groove 20.21 is provided in No. 4, the positive electrode side electrode 12 and the negative electrode side electrode 15 can be manufactured by the same method.

Embodiment 3. A lithium secondary battery according to another embodiment of the present invention will be described below. In this lithium secondary battery, the electrodes are joined to the separator via the polymer electrolyte layer to facilitate the handling of the electrode pair. For example, the positive electrode active material layer 11 of the positive electrode 12 having the grid-shaped grooves 23 described in the first embodiment shown in FIG.
A polymer electrolyte layer having a skeleton of polyethylene oxide and containing a lithium perchlorate salt is applied to the negative electrode active material layer 14 of the negative electrode 15 on which No. 4 is formed by a doctor blade method to a thickness of 10 μm. Next, a separator 16 made of a polypropylene porous sheet is sandwiched between the positive electrode 12 and the negative electrode 15, and these are pressed and bonded at a pressure of 2 kg / cm2 to form an electrode pair 17
To form. Next, as shown in FIG. 9, the electrode pair 17 is folded in two and wound on a bobbin 18, which is then placed in a stainless steel can 1 as shown in FIG.
Insert in 9. Then, an electrolyte solution containing ethylene carbonate and dimethoxyethane as a solvent and a lithium perchlorate salt as an electrolyte is injected into the inside, and then a sealing process is performed to manufacture a lithium secondary battery.

As described above, in this lithium secondary battery, the electrodes 12 and 15 in which the grid-like grooves 23 and 24 are formed are bonded to the separator 16 via the polymer electrolyte layer, and therefore the electrode pair is formed. When winding up (winding) the electrode pair 17, the electrode pair 17 can be used in an amount of 30 times as much as the conventional electrode pair without worrying about the positional deviation between the positive electrode side electrode 12 and the negative electrode side electrode 15.
I was able to wind up at a high speed. Of course, electrode 1
Since the grid-shaped grooves 23 and 24 are formed in the layers 2 and 15, no undesired cracking occurs in the active material layers 11 and 14 during winding.

FIG. 11 is a discharge curve of the battery. It can be seen from the figure that the voltage drop during discharge is larger in the battery of curve b using the polymer electrolyte layer as in this embodiment than in the battery of curve a not using the polymer electrolyte layer. Is clear. This is due to the fact that the conductivity of the polymer electrolyte layer is smaller than that of other portions, but this difference in voltage drop does not pose a practical problem.

The same effect can be obtained by joining the electrodes 12 and 15 having the electrode bending grooves 20 and 21 to the separator 16 through the polymer electrolyte layer.

Further, for example, a mask having a predetermined aperture ratio is used as the electrode 1.
After being applied to the active material layers 11 and 14 of No. 2 and 15, the polymer electrolyte layer is applied to the active material layers 11 and 14 from above to reduce the application area of the polymer electrolyte layer. Alternatively, the resistance of the battery may be reduced.

Here, the area of the joint portion of the active material layers 11 and 14 is Sa, the area of the non-joint portion is Sb, the ratio of the thickness to the conductivity of the polymer electrolyte layer is Tp, and the conductivity of the electrolyte solution is If the value of the ratio of the effective thickness of the separator 16 in consideration of the bending rate to the degree is Tq, the ion conduction resistance R
The ion conduction resistance Rb of a and the non-junction portion is expressed by Ra = (Tq + Tp) × Sa (6) Rb = Tq / Sb.

If the active material layer is uniform, the reaction current in the battery is almost inversely proportional to the ionic conduction resistance. Therefore, the variation in the reaction current in the battery, that is, Ra / Rb = Sb, rather than the reaction pattern. X (Tp / Tq + 1) / Sa (8) Therefore, 0.9 <Ra /
If Rb <1.1, the reaction bias is -10% to +
It can be suppressed within 10%, and the output of the battery can be increased.

Here, the aperture ratio of the mask is set to, for example, 13
%, This can reduce the ion conduction resistance by 43% as compared with the case where no mask is used, and r
= Sb / Sa value, the reaction pattern in the battery can be calculated as -0.
It can be set within the range of 3% to + 0.3%.

The separator 1 in consideration of the above bending rate
The effective thickness of 6 is a moving distance of the electrolyte ions moving along the bent hole inside the separator 16 which is a porous body, and an experimentally obtained constant (flexibility) is set to an apparent thickness. It's a hang.

Further, the lithium salt contained in the polymer electrolyte layer is not the same perchlorate salt as the electrolyte salt contained in the electrolytic solution of the battery, but is, for example, a tetrafluoroboron salt (lithium tetrafluoroborate). By doing so, the ionic conduction resistance increases by 40% as compared with the case of perchlorate, and the discharge characteristics deteriorate as shown by the curve c in FIG. That is, when the lithium salt contained in the polymer electrolyte layer is the same as the anion or cation of the electrolyte salt contained in the electrolytic solution of the battery, the output characteristics of the battery are improved. By the way, if the above-mentioned perchlorate is a CuI salt, the discharge characteristics of the battery are extremely deteriorated as shown by the curve d in FIG.

[0053]

EFFECTS OF THE INVENTION (1) The battery of the present invention comprises first and second electrodes having an active material layer and a current collector in close contact with each other, and a separator sandwiched between the first electrode and the second electrode. And an electrolyte, and the active material layer of at least one of the first and second electrodes and the separator are bonded by the polymer electrolyte layer to form an electrode pair, so that the separator and the electrode are not misaligned. It does not occur and the effective area contributing to the electrode reaction is not impaired.

(2) In the contact area of the active material layer with the separator, the value of the ratio of the area of the non-bonded portion to the area of the bonded portion of the polymer electrolyte layer is r, and the ionic conductivity of the polymer electrolyte layer is The value of the ratio of the thickness of the polymer electrolyte layer to Tp was defined as Tp, and the value of the ratio of the effective thickness of the separator taking into consideration the bending ratio of the electrolyte used in this battery with respect to the ionic conductivity was defined as Tq. In this case, the relationship of 0.9 <r × (Tp / Tq + 1) <1.1 is established, and the reaction current in the battery surface is almost inversely proportional to the ion conduction resistance if the active material of the electrode is uniform. Therefore, the variation of the reaction current, that is, the reaction bias can be suppressed between 90% and 110%.

(3) Since the anion or cation of the electrolyte salt contained in the polymer electrolyte layer is the same as the anion or cation of the electrolyte salt constituting the active material layer, the reactivity of the electrode is not impaired. (4) Further, since the separator joined by the polymer electrolyte layer and at least one of the first electrode and the second electrode are wound, the electrode and the separator are not displaced and can be easily wound. (5) Further, since the electrolytic solution is composed of a lithium salt and an aprotic organic solvent, the battery performance can be maintained. (6) Further, since the aprotic organic solvent contains ethylene carbonate, the battery performance can be maintained. (7) Furthermore, the method for producing a battery of the present invention comprises a step of forming a positive electrode by bringing the positive electrode active material layer and the positive electrode current collector into close contact with each other,
A step of forming a negative electrode by bringing the negative electrode active material layer and the negative electrode current collector into close contact with each other, and a step of forming a pair of electrodes by adhering at least one of the positive electrode and the negative electrode and the separator by the polymer electrolyte layer. Therefore, the battery and the separator do not shift. (8) Further, the step of injecting the electrolytic solution is provided after the step of adhering at least one of the positive electrode and the negative electrode to the separator by the polymer electrolyte layer and forming the electrode pair. Can be done after the joining process.

[Brief description of drawings]

FIG. 1 is a schematic side view of a battery electrode device of a lithium secondary battery as a reference example for explaining a battery of the present invention.

FIG. 2 is a schematic side view of a bent portion of the battery electrode device of FIG.

FIG. 3 is an explanatory diagram of a reference example in which only one electrode bending groove is formed in the electrode arranged outside the bending portion of the battery electrode device.

FIG. 4 is an explanatory diagram of a reference example in which a plurality of electrode bending grooves are formed in an electrode arranged outside a bending portion of a battery electrode device.

5 is a schematic diagram showing another reference example for the explanatory diagram of FIG. 4. FIG.

FIG. 6 is a schematic view showing a forming range in the case where an electrode bending groove is formed in an electrode arranged outside the bending portion of the battery electrode device.

FIG. 7 is a schematic side view of an electrode device for a battery of a lithium secondary battery in which an electrode bending groove is formed in consideration of a compressibility of an active material layer.

FIG. 8 is an exploded perspective view of a battery electrode device for a lithium secondary battery according to an embodiment of the present invention.

9 is a perspective view of the battery electrode device of FIG. 8 folded in half.

FIG. 10 is a diagram showing an overall outline of the lithium secondary battery of FIG.

FIG. 11 is a graph showing discharge characteristics of various lithium secondary batteries including those of the present invention.

FIG. 12 is a diagram showing an example of a conventional lithium secondary battery.

[Explanation of symbols]

10 positive electrode current collector (current collector), 11 positive electrode active material layer (active material layer), 12 positive electrode side electrode (first electrode), 13 negative electrode current collector (current collector), 14 negative electrode active material layer ( Active material layer), 15 Negative electrode (second electrode) 16 Separator, 17 Battery electrode (electrode pair), 17a Bent portion, 2
0 electrode bent groove, 21 electrode bent groove, 23 grid groove,
24 grid-like grooves, d1 thickness of positive electrode active material layer (thickness of electrode), d2 thickness of negative electrode active material layer (thickness of electrode).

Continuation of the front page (56) Reference JP-A-7-192725 (JP, A) JP-A-6-36801 (JP, A) JP-A-7-65836 (JP, A) JP-A-7-235329 (JP , A) JP-A-6-140077 (JP, A) US Patent 5456000 (US, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01M 10/40

Claims (8)

(57) [Claims] 1. A first electrode and a second electrode having an active material layer and a current collector which are in close contact with each other, and the first electrode and the second electrode.
A separator sandwiched between the electrodes, of the adhesive and an electrolyte, at least one of the active material layer of the first and second electrodes, and the separator by a polymer electrolyte layer
The battery is characterized by forming an electrode pair . 2. A value of a ratio of an area of a non-bonded portion to an area of a bonded portion of the polymer electrolyte layer, out of a contact area of the active material layer with the separator, is expressed by r, and an ion conductivity of the polymer electrolyte layer is expressed. Tp is the value of the ratio of the thickness of this polymer electrolyte layer to Tq, and Tq is the value of the ratio of the effective thickness of the separator taking into account the tortuosity to the ionic conductivity of the electrolyte used in this battery. When it does, the battery of Claim 1 with which 0.9 <rx (Tp / Tq + 1) <1.1 is materialized. 3. The battery according to claim 1, wherein the anion or cation of the electrolyte salt contained in the polymer electrolyte layer is the same as the anion or cation of the electrolyte salt constituting the active material layer. 4. The battery according to claim 1, wherein the separator joined by the polymer electrolyte layer, and at least one of the first electrode and the second electrode are wound. 5. The battery according to claim 1, wherein the electrolytic solution is composed of a lithium salt and an aprotic organic solvent. 6. The battery according to claim 1, wherein the aprotic organic solvent contains ethylene carbonate. 7. A step of forming a positive electrode by adhering a positive electrode active material layer and a positive electrode current collector, a step of forming a negative electrode by adhering a negative electrode active material layer and a negative electrode current collector, and a polymer electrolyte to layer
The method of manufacturing a battery, further comprising : adhering at least one of the positive electrode and the negative electrode to the separator to form an electrode pair . 8. A positive electrode and a negative electrode with a polymer electrolyte layer.
At least one of the
And a step of injecting an electrolytic solution after the step of forming
A method of manufacturing a battery according to claim 7 .