JP2012038628A - Nonaqueous electrolyte battery and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery of which the productivity can be improved and which can suppress reduction in battery characteristics at the end of discharge, and also to provide a method of manufacturing the battery.SOLUTION: The battery includes: a positive electrode can; a negative electrode can; a positive electrode material provided on the surface opposite to the negative electrode can out of the surfaces of the positive electrode can; and a negative electrode material provided on the surface opposite to the positive electrode can out of the surfaces of the negative electrode can; a gasket interposed at the peripheral part between the positive electrode can and the negative electrode can; and a positive electrode ring to cover the side surface of the positive electrode material. The gasket includes a plurality of projects or extension parts for positioning the positive electrode material.

Description

  The present invention relates to a nonaqueous electrolyte battery and a method for manufacturing the same. Specifically, the present invention relates to a nonaqueous electrolyte battery in which a gasket is interposed between a positive electrode can and a negative electrode can.

  In recent years, a lithium battery or the like has been used as a driving power source, and the demand for large current is increasing. In the coin-type lithium battery, the negative electrode active material lithium enters the positive electrode pellet as lithium ions, and is discharged. Therefore, this battery is characterized in that the volume of the negative electrode decreases with discharge, whereas the volume of the positive electrode pellet expands. During discharge, if the expansion in the thickness direction of the positive electrode pellet is less than the decrease in the thickness direction of the negative electrode, the contact between the two electrodes becomes insufficient, the internal resistance increases, and the load characteristics decrease. In order to avoid this problem, various battery structures have been proposed. As a typical example, there is a battery structure using a positive electrode ring (see, for example, Patent Document 1). When the positive electrode ring is used, the side surface of the positive electrode pellet is fixed by the rigid positive electrode ring, so that most of the volume expansion of the positive electrode pellet accompanying discharge is distributed in the thickness direction, and the expansion in the thickness direction increases and discharge occurs. The contact between positive and negative electrodes is improved.

JP 2008-103109 A

  However, in the above battery configuration, from the viewpoint of battery characteristics, it is necessary to reduce the clearance between the positive electrode ring and the positive electrode pellet. If the clearance is reduced in this way, the positive electrode ring and the positive electrode pellet are separately assembled in the assembly process. It becomes difficult.

  As a method for avoiding such a problem, a method in which the positive electrode pellet and the positive electrode ring are integrated in advance before the assembly process can be considered. However, in the case where the positive electrode pellet and the positive electrode ring are integrated in this way, it is necessary to work with attention to inversion in the assembly process. Therefore, when the above method is adopted, compared to a battery not using the positive electrode ring. Productivity will be reduced.

  Therefore, in order to suppress such a decrease in productivity, a method is conceivable in which a positive electrode can and a positive electrode ring are welded, and a positive electrode pellet is integrated with this to assemble a battery. However, this method requires a step of reversing and assembling the positive electrode can after the electrolytic solution is dropped onto the positive electrode pellet. In this step, when the electrolyte overflows due to the reversal of the positive electrode can, the yield is deteriorated. By suppressing the speed of the production line, overflow of the electrolyte can be suppressed. However, if the speed of the production line is reduced in this way, productivity is lowered.

  Further, in the above-described method, since the electrolyte solution is dropped while the side surface of the positive electrode pellet and the positive electrode ring are in close contact with each other, absorption of the electrolyte solution of the positive electrode pellet becomes insufficient during battery assembly. As a result, there arises a problem that sufficient battery characteristics cannot be maintained until the end of discharge consumed by the electrolytic solution.

  An object of the present invention is to provide a nonaqueous electrolyte battery capable of improving productivity and suppressing deterioration of battery characteristics at the end of discharge and a method for producing the same.

In order to solve the above-mentioned problem, the first invention
A positive electrode can,
A negative electrode can,
Among the surfaces of the positive electrode can, the positive electrode material provided on the surface facing the negative electrode can,
Of the negative electrode can surface, the negative electrode material provided on the surface facing the positive electrode can,
A gasket interposed between the peripheral edges of the positive electrode can and the negative electrode can;
A positive ring covering the side of the positive electrode material,
The gasket is a battery having a plurality of projecting portions or extending portions for positioning the positive electrode material.

The second invention is
A step of disposing a gasket having a plurality of protruding portions or extending portions on the peripheral edge of the negative electrode can;
Positioning the positive electrode material by a plurality of protrusions or extending parts, and placing on the negative electrode can;
The negative electrode can on which the positive electrode material is arranged and the positive electrode can on which the ring member is joined are overlapped so that the positive electrode material and the ring member face each other, and the peripheral portion of the overlapped negative electrode can and positive electrode can is covered. And a step of producing a battery.

  In the present invention, the positive electrode material is positioned by a plurality of projecting portions or extending portions of the gasket and disposed on the negative electrode can, and then the positive electrode can with the positive electrode ring pre-bonded and the negative electrode can are overlapped to form a battery. Make it. Therefore, the process of integrating the positive electrode ring and the positive electrode material in advance is unnecessary, and a decrease in productivity when a battery configuration using the positive electrode ring is adopted can be suppressed. Moreover, substantially the same productivity as a battery not using a positive electrode ring can be realized.

  In addition, after positioning the positive electrode material with the protruding portion of the gasket and placing it in the negative electrode can, the side surface of the positive electrode material is not covered with the positive electrode ring, and in an exposed state, the positive electrode material is impregnated with the electrolyte solution. The impregnation property of the electrolytic solution can be improved. Therefore, it is possible to suppress a decrease in battery characteristics at the end of discharge. That is, superior battery characteristics can be realized as compared with a conventional battery using a positive electrode ring.

  As described above, according to the present invention, the step of previously integrating the positive electrode ring and the positive electrode material can be omitted, so that productivity can be improved. Moreover, since the impregnation property of the positive electrode material with the electrolytic solution can be improved, it is possible to suppress a decrease in battery characteristics at the end of discharge.

FIG. 1 is a cross-sectional view showing an example of the configuration of a nonaqueous electrolyte battery according to an embodiment of the present invention. FIG. 2A is a plan view showing a first example of a gasket shape. 2B is a cross-sectional view taken along line AA shown in FIG. 2A. FIG. 3A is a plan view showing a second example of the shape of the gasket. 3B is a cross-sectional view taken along line AA shown in FIG. 3A. FIG. 4A is a plan view showing an example of the shape of the positive electrode ring. 3B is a cross-sectional view taken along line AA shown in FIG. 3A. 5A to 5C are process diagrams for explaining an example of a method for manufacturing a nonaqueous electrolyte battery according to an embodiment of the present invention. 6A to 6C are process diagrams for explaining an example of a method for manufacturing a nonaqueous electrolyte battery according to an embodiment of the present invention. FIG. 7A is a cross-sectional view showing a first modification of the positive electrode ring. FIG. 7B is a cross-sectional view illustrating a second modification of the positive electrode ring.

[Configuration of non-aqueous electrolyte battery]
FIG. 1 is a cross-sectional view showing an example of the configuration of a nonaqueous electrolyte battery according to an embodiment of the present invention. This non-aqueous electrolyte battery is a so-called coin-type lithium battery, and includes a positive electrode can 1, a positive electrode pellet (positive electrode material) 2, a negative electrode cup (negative electrode can) 3, a negative electrode material 4, a separator 5, A gasket 6, a positive electrode ring 7, and an electrolytic solution are provided. The positive electrode pellet 2 is provided on the surface of the positive electrode can 1 that faces the negative electrode cup 3, and the negative electrode material 4 is provided on the surface of the negative electrode cup 3 that faces the positive electrode can 1. The gasket 6 is interposed at the peripheral portion of the positive electrode can 1 and the negative electrode cup 3, and the positive electrode can 1, the negative electrode cup 3 and the peripheral portion are caulked with the gasket 6 interposed. The positive electrode ring 7 covers the side surface of the positive electrode material 2 and is bonded to the positive electrode can 1. The insides of the positive electrode can 1 and the negative electrode cup 3 are filled with an electrolytic solution that is a liquid electrolyte, for example. Moreover, you may make it further provide an aluminum foil in the positive electrode pellet side of the negative electrode material 4 as needed. By providing the aluminum foil in this way, the load characteristics can be further improved.
Hereinafter, the positive electrode can 1, the negative electrode cup 3, the positive electrode pellet 2, the negative electrode material 4, the separator 5, the electrolyte solution, the gasket 6, and the positive electrode ring 7 constituting the nonaqueous electrolyte battery will be described in order.

(Positive electrode can, negative electrode cup)
The positive electrode can 1 is made of, for example, a metal such as stainless steel, and the negative electrode cup 3 is made of, for example, a metal such as iron or stainless steel plated with nickel. The positive electrode can 1 functions as a current collector for the positive electrode pellet 2, and the negative electrode cup 3 functions as a current collector for the negative electrode material 4.

(Positive electrode pellet)
The positive electrode pellet has, for example, a disk shape. The positive electrode pellet 2 includes, for example, a positive electrode active material, and includes a conductive agent and a binder (binder) as necessary. Examples of the positive electrode active material include baked electrolytic manganese dioxide (β manganese dioxide). Examples of the conductive agent include graphite, carbon black, acetylene black, and carbon fiber. Examples of the binder include polyvinylidene fluoride, polytetrafluoroethylene, hexafluoropropylene, a copolymer of polyvinylidene fluoride and hexafluoropropylene, and styrene butadiene rubber.

(Negative electrode material)
The negative electrode material 4 has, for example, a disk shape. The negative electrode material 4 contains, for example, lithium or a lithium alloy as a negative electrode active material. Examples of the lithium alloy include aluminum (Al), lead (Pb), tin (Sn), bismuth (Bi), cadmium (Cd), copper (Cu), and iron (Fe) as the second constituent element other than lithium. And at least one member selected from the group consisting of:

(Separator)
The separator 5 separates the positive electrode pellet 2 and the negative electrode material 4 and allows lithium ions to pass through while preventing a short circuit of the electrode due to contact between both electrodes. The separator 5 is made of, for example, a porous film made of a synthetic resin made of polytetrafluoroethylene, polyphenylene sulfide, polypropylene, polyethylene, or the like, or a porous film made of an inorganic material such as a ceramic nonwoven fabric.

(Electrolyte)
An electrolyte solution as an electrolyte is obtained by dissolving a lithium salt as an electrolyte salt in an organic solvent, and exhibits ion conductivity when the lithium salt is ionized. Here, examples of the organic solvent include esters, ethers, trisubstituted-2-oxazolidinones, and a mixed solvent of two or more thereof. Examples of the esters include alkylene carbonates (ethylene carbonate, propylene carbonate, γ-butyl lactone, 2-methyl-γ-butyl lactone, etc.). Examples of ethers include diethyl ether, cyclic ethers such as ethers having a 5-membered ring [tetrahydrofuran; substituted (alkyl, alkoxy) tetrahydrofurans such as 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, 2-ethyltetrahydrofuran, 2, 2′-dimethyltetrahydrofuran, 2-methoxytetrahydrofuran, 2,5-dimethoxytetrahydrofuran, etc .; dioxolane, etc.], ethers having a 6-membered ring [1,4-dioxane, pyran, dihydropyran, tetrahydropyran], dimethoxyethane, etc. It is done. Examples of the 3-substituted-2-oxazolidinones include 3-alkyl-2-oxazolidinones (3-methyl-2-oxazolidinone, 3-ethyl-2-oxazolidinone, etc.), 3-cycloalkyl-2-oxazolidinones (3-cyclohexyl). 2-oxazolidinone, etc.), 3-aralkyl-2-oxazolidinone (3-benzyl-2-oxazolidinone, etc.), and 3-aryl-2-oxazolidinone (3-phenyl-2-oxazolidinone, etc.). Of these, propylene carbonate, ethers having a 5-membered ring (particularly tetrahydrofuran, 2-methyltetrahydrofuran, 2-ethyltetrahydrofuran, 2,5-dimethoxytetrahydrofuran, 2-methoxytetrahydrofuran), 3-methyl-2-oxazolidinone, and the like are preferable.

  As the electrolyte salt, for example, lithium perchlorate, lithium borofluoride, lithium phosphofluoride, lithium chloroaluminate, lithium halide, lithium trifluoromethanesulfonate, etc. can be used, such as lithium perchlorate, lithium borofluoride, etc. Is preferred.

(gasket)
The gasket has, for example, a ring shape. The gasket includes a main body portion 11 and a plurality of projecting portions 12 a or extending portions 12 b provided on the inner peripheral side of the main body portion 11. The main body portion 11 is a seal portion that is interposed in the peripheral portions of the positive electrode can 1 and the negative electrode cup 3 and seals a gap between them. The main body 11 can prevent leakage of the electrolytic solution from the inside of the nonaqueous electrolyte battery to the outside and contamination of foreign matters such as moisture from the outside of the nonaqueous electrolyte battery to the inside.

  The protruding portion 12a or the extending portion 12b is for positioning the positive electrode pellet 2 during the manufacture of the nonaqueous electrolyte battery. The protruding portion 12 a or the extending portion 12 b protrudes or extends toward the center of the battery, and the tip thereof is located on the side surface of the positive electrode pellet 2. The shape of the protruding portion 12a or the extending portion 12b is not particularly limited as long as the position of the positive electrode pellet 2 can be fixed in the manufacturing process of the nonaqueous electrolyte battery. Examples of the material of the annular gasket include, for example, fluorine resin such as polypropylene, nylon, tetrafluoroethylene-perfluoroalkoxyethylene copolymer (PFA), polyphenylene ether (PPE), polysulfone (PSF), polyarylate (PAR), Examples include polyether sulfone (PES), polyphenylene sulfide (PPS), and polyether ether ketone (PEEK).

  FIG. 2A is a plan view showing a first example of a gasket shape. 2B is a cross-sectional view taken along line AA shown in FIG. 2A. The gasket 6 includes a ring-shaped main body portion 11 and a plurality of projecting portions 12 a provided at the distal end portion on the inner peripheral side of the main body portion 11. These protrusions 12 a protrude toward the exposed areas that are not covered by the positive electrode ring 7 and are exposed on the side surface of the positive electrode pellet 2. During the manufacture of the nonaqueous electrolyte battery, the positive electrode pellet 2 is positioned by these protrusions 12a. From the viewpoint of facilitating the positioning of the positive electrode pellet 2 during the manufacture of the nonaqueous electrolyte battery, the number of the protrusions 12a is preferably 3 or more. Further, from the viewpoint of facilitating the positioning of the positive electrode pellet 2 at the time of manufacturing the nonaqueous electrolyte battery, the plurality of protruding portions 12a are preferably provided at equal intervals on the inner periphery of the ring-shaped main body portion 11. The shape of the protrusion 12a is not particularly limited as long as it is a shape capable of positioning the positive electrode pellet 2 at the time of manufacturing the nonaqueous electrolyte battery.

  FIG. 3A is a plan view showing a second example of the shape of the gasket. 3B is a cross-sectional view taken along line AA shown in FIG. 3A. The gasket 6 includes a ring-shaped main body portion 11 and a ring-shaped extension portion 12b in which the entire front end portion on the inner peripheral side of the main body portion 11 protrudes uniformly. The extending portion 12 b extends from the inner periphery of the main body portion 11 uniformly in a ring shape toward the exposed region that is not covered by the positive electrode ring 7 and exposed in the side surface of the positive electrode pellet 2. When the nonaqueous electrolyte battery is manufactured, the positive electrode pellet 2 is positioned by the extending portion 12b.

(Positive electrode ring)
FIG. 4A is a plan view showing an example of the shape of the positive electrode ring. 4B is a cross-sectional view taken along line AA shown in FIG. 4A. The positive electrode ring 7 is a metal ring having an L-shaped cross section, for example. Specifically, a ring-shaped joint portion 21 welded to the positive electrode can 1 and a peripheral wall portion 22 erected at right angles to the outer peripheral portion of the joint portion 21 are provided. From the viewpoint of improving the current collection effect of the battery, it is preferable that the joint 21 is welded to the positive electrode can 1. Similarly, from the viewpoint of improving the current collecting effect of the battery, it is preferable that the peripheral wall portion 22 and the side surface of the positive electrode pellet 2 are in close contact with each other. Examples of the material of the positive electrode ring 7 include metals such as stainless steel, but are not particularly limited to this material.

The height of the peripheral wall portion 22 of the positive electrode ring 7 can be designed as appropriate, but it is preferable to make it sufficiently large as long as it does not interfere with the protruding portion 12a or the extending portion 12b of the gasket 6. This is because the peripheral wall portion 22 of the positive electrode ring 7 can suppress the expansion of the positive electrode pellet 2 in the radial direction and increase the book length in the thickness direction. Specifically, the ratio of the height h of the peripheral wall portion 22 of the positive electrode ring 7 to the height H of the positive electrode pellet 2 ((h / H) × 100) is preferably 40% or more. The smaller the difference between the inner diameter D _A of the positive electrode ring 7 and the inner diameter D _{B of the} gasket 6, that is, the smaller the clearance between the inner diameter D _A of the positive electrode ring 7 and the outer diameter of the positive electrode pellet 2, the more the pellet expansion associated with discharge occurs. The characteristics are distributed in the height direction, and the characteristics at the end of discharge are further improved.

The ratio (D _A / D _B ) between the inner diameter D _A of the positive electrode ring 7 and the inner diameter D _{B of the} gasket 6 is preferably 0.97 or more and 1.10 or less, more preferably 1.00 or more and 1.10 or less. Within range. If it is less than 0.97, the productivity tends to decrease. On the other hand, if it exceeds 1.10, the battery characteristics at the end of discharge tend to deteriorate. Moreover, a yield can be improved as it is 1.00 or more. Here, the inner diameter of the positive electrode ring 7 is the inner diameter of the peripheral wall portion 22 of the positive electrode ring 7, that is, the distance between the inner peripheral surfaces of the peripheral wall portion 22 of the positive electrode ring 7, as shown in FIG. 4A. The inner diameter D _B of the gasket 6, the distance between the between the projections or extension part, is specifically defined as follows. As shown in FIG. 2A, the main body portion 11 of the gasket 6, when a plurality of projecting portions 12 are provided, the diameter D _B of the virtual circle C the tip of the protrusion 12 is located. As shown in FIG. 3A, the main body portion 11 of the gasket 6, when the uniformly protruding annular extending portion 12b is provided, the diameter D _B of the ring-shaped extending portion 12b.

(1-2) Method for Manufacturing Nonaqueous Electrolyte Battery Hereinafter, an example of a method for manufacturing a nonaqueous electrolyte battery according to an embodiment of the present invention will be described with reference to FIGS. 5A to 6C.

  First, as shown in FIG. 5A, the disc-shaped negative electrode material 4 is accommodated in the negative electrode cup 3. Next, as shown in FIG. 5B, the separator 5 is placed on the negative electrode material 4. Next, as shown in FIG. 5C, the ring-shaped gasket 6 is placed on the peripheral edge of the negative electrode cup 3. As a molding method of the gasket 6, for example, an injection molding method can be mentioned. Next, an electrolytic solution is dropped onto the separator 5.

  Next, as shown in FIG. 6A, the positive electrode pellet 2 is positioned at a predetermined position of the negative electrode cup 3 while the positive electrode pellet 2 is positioned by the protruding portion 12 a or the extending portion 12 b of the gasket 6. For example, the positive electrode pellet 2 is obtained by mixing fired electrolytic manganese dioxide, a conductive material such as graphite, a binder such as polytetrafluoroethylene (PTFE), and water, followed by heat treatment to evaporate and dry the water. It is obtained by molding into a pellet. Next, an electrolytic solution is dropped onto the positive electrode pellet 2.

  Next, as shown in FIG. 6B, the positive electrode can 1 is covered with the positive electrode can 1 in which the positive electrode ring 7 is previously welded to the surface facing the negative electrode cup 3. Examples of the welding method include resistance welding or laser welding. Next, as shown in FIG. 6C, the periphery of the positive electrode can 1 and the negative electrode cup 3 is sealed by caulking through a gasket 7. As a result, the intended nonaqueous electrolyte battery is obtained.

[Modification]
You may make it at least a front-end | tip part expands toward the outer side among the surrounding wall parts 22 of a positive electrode ring. By adopting such a shape, productivity can be improved. Specifically, for example, as shown in FIG. 7A, the peripheral wall portion 22 may be inclined with respect to the ring-shaped joint portion 21 so that the peripheral wall portion 22 spreads outward toward the tip end portion. Moreover, as shown to FIG. 7B, you may make it open only the front-end | tip part of the surrounding wall part 22 toward an outer side. If the ratio (D _C / D _A ) between the inner diameter D _C of the distal end portion of the peripheral wall portion 22 of the positive electrode ring 7 and the inner diameter D _A on the joint portion 21 side of the positive ring 7 becomes too large, the positive electrode in the radial direction The expansion of the pellet 2 increases, the expansion of the positive electrode pellet 2 in the thickness direction decreases, and the closed circuit voltage tends to decrease by a discharge depth of 80%. Therefore, the ratio (D _C / D _A ) is preferably 1.05 or less.

  As described above, in this embodiment, the positive electrode pellet 2 is positioned while being positioned at the center of the negative electrode cup 3 or the like by the plurality of projecting portions 12 a or the extending portions 12 b of the gasket 6. And the positive electrode can 1 by which the positive electrode ring 7 was welded beforehand is piled up on the negative electrode cup 3, and those non-aqueous electrolyte batteries are produced by caulking those peripheral parts. Therefore, the process of integrating the positive electrode ring 7 and the positive electrode pellet 2 in advance is not required, and it is possible to suppress a decrease in assembly speed and yield due to the use of the positive electrode ring 7.

  Further, by welding the positive electrode can 1 and the positive electrode ring 7 in advance, a nonaqueous electrolyte battery can be manufactured in substantially the same manner as the manufacturing process when the positive electrode ring 7 is not used. Therefore, a nonaqueous electrolyte battery having the positive electrode ring 7 can be produced without significantly modifying the conventional production line.

  Furthermore, the electrolyte is dropped onto the positive electrode pellet 2 in a state where the positive electrode pellet 2 and the positive electrode ring 7 are integrated in advance and the side surface of the positive electrode pellet 2 is not covered with the positive electrode ring 7 but the side surface of the positive electrode pellet 2 is exposed. Or the like. Therefore, compared with the conventional nonaqueous electrolyte battery using the positive electrode ring 7, the electrolyte solution absorptivity of the positive electrode pellet 2 can be improved. That is, battery characteristics such as the end of discharge can be improved as compared with the conventional nonaqueous electrolyte battery using the positive electrode ring 7.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited only to these Examples.

In the following examples and comparative examples, the ratio (D _A / D _B ) was determined as follows.
First, to measure the inner diameter D _A of the cathode ring with inner micrometer. Next, the tool microscope (Topcon Co., Ltd., trade name: TUM) were measured inner diameter D _B of the gasket used. Next, the ratio (D _A / D _B ) was determined by using the measured positive electrode ring inner diameter D _A and gasket inner diameter D _B.

Example 1
First, a disc-shaped negative electrode material made of lithium having a diameter of 20 mm was pressure-bonded to a stainless steel negative electrode cup, and then a polypropylene separator was placed on the negative electrode material. Next, a polypropylene gasket was disposed on the peripheral edge of the negative electrode cup. As the gasket, one having six protrusions provided uniformly on the inner peripheral portion was used. Next, an electrolytic solution composed of lithium perchlorate, propylene carbonate, and dimethoxyethane was dropped onto the separator.

Next, the positive electrode pellet was accommodated in the negative electrode cup so as to fit inside the protruding portion of the gasket, and an electrolytic solution having the same components as above was dropped onto the positive electrode pellet. As the positive electrode pellet, one produced by pressure molding a mixture containing manganese dioxide as a main component was used. Next, a positive electrode can in which a ring was previously welded by laser welding was prepared. The ratio (D _A / D _B ) between the inner diameter D _{A of the} positive ring and the inner diameter D _{B of the} gasket was 1.00. Next, after covering the negative electrode cup with the positive electrode can, the peripheral part of the positive electrode can and the negative electrode cup was sealed by caulking through a gasket.
As a result, a coin type lithium battery having a battery outer diameter of 24 mm and a total height of 5.0 mm was obtained.

(Example 2)
_A coin-type lithium battery was fabricated in the same manner as in Example 1 except that the positive electrode ring inner diameter was increased and the ratio (D _A / D _B ) between the inner diameter D _{A of the} positive ring and the inner diameter D _{B of the} gasket was 1.05. Obtained.

(Example 3)
_A coin-type lithium battery was fabricated in the same manner as in Example 1, except that the positive electrode ring inner diameter was increased and the ratio (D _A / D _B ) between the inner diameter D _{A of the} positive ring and the inner diameter D _{B of the} gasket was 1.10. Obtained.

Example 4
By increasing the cathode ring inner diameter, except that the ratio of the inner diameter D _A and the gasket inside diameter D _B of the positive electrode ring (D _A / D _B) and 1.15 in the same manner as in Example 1, a coin-type lithium battery Obtained.

(Example 5)
Reducing the cathode ring inner diameter, except that the ratio of the inner diameter D _A and the gasket inside diameter D _B of the positive electrode ring (D _A / D _B) and 0.97 in the same manner as in Example 1, a coin-type lithium battery Obtained.

(Example 6)
A positive electrode ring in which the tip of the peripheral wall portion is bent outward is molded, and the ratio (D _A / D _B ) between the inner diameter D _{A of the} positive electrode ring and the inner diameter D _{B of the} gasket is 0.97. The ratio (D _C / D _B ) between D _C and the inner diameter D _{B of the} gasket was 1.00. Here, the inner diameter D _A of the positive electrode rings, of the peripheral wall portion of the positive electrode rings, an inner diameter of the portion of the joint portion than bent tip. The inner diameter D _C of the positive electrode ring tip, of the peripheral wall portion of the positive electrode ring is advanced inside diameter of the bent tip. Except for this, a coin-type lithium battery was obtained in the same manner as in Example 1.

(Comparative Example 1)
A coin-type lithium battery was obtained in the same manner as in Example 1 except that a ring-shaped member having no protruding portion was used as the gasket and a positive electrode can having no positive electrode ring was used.

(Comparative Example 2)
First, a disc-shaped negative electrode material made of lithium having a diameter of 20 mm was pressure-bonded to a stainless steel negative electrode cup, and then a polypropylene separator was placed on the negative electrode material. Next, a polypropylene gasket was disposed on the peripheral edge of the negative electrode cup. As the gasket, a ring-shaped gasket having no protrusion was used. Next, an electrolytic solution composed of lithium perchlorate, propylene carbonate, and dimethoxyethane was dropped onto the separator.

Next, after preparing a positive electrode can in which the positive electrode ring was previously welded with a laser welder, the positive electrode pellet was inserted into the positive electrode ring and integrated by pressure molding, and then an electrolyte solution was dropped onto the positive electrode pellet. As the positive electrode pellet, one produced by pressure molding a mixture containing manganese dioxide as a main component was used. Next, the positive electrode can was inverted and covered on the negative electrode cup, and the periphery of the positive electrode can and the negative electrode cup was sealed by caulking through a gasket.
Thus, a coin-type lithium battery having a battery outer diameter of 24 mm and a total height of 5.0 mm was produced.

(Productivity evaluation)
The assembly speed and yield of the coin-type lithium batteries of Examples 1 to 6 and Comparative Examples 1 and 2 were evaluated. Table 1 shows the results. The assembly speed (line speed) is shown as a relative value with the assembly speed (line speed) of Comparative Example 1 as the reference value “100”. Further, the yield (also referred to as a yield rate) was expressed as a relative value with the yield of Comparative Example 1 being “100”. Here, the yield is a ratio of coin-type lithium batteries manufactured at a predetermined time that satisfy predetermined battery performance (predetermined voltage, predetermined battery size, and appearance).

(Evaluation of battery characteristics)
The closed circuit voltage after 30 mA of current for 1 second at 23 ° C. with the discharge depth of 0% and the discharge depth of 80% of the coin-type lithium batteries of Examples 1 to 6 and Comparative Examples 1 and 2 was determined. The results are shown in Table 2.

Table 1 shows the evaluation results of the productivity of the coin-type lithium batteries of Examples 1 to 6 and Comparative Examples 1 and 2.

Table 2 shows the evaluation results of the battery characteristics of the coin-type lithium batteries of Examples 1 to 6 and Comparative Examples 1 and 2.

Table 1 shows the following.
In Comparative Example 2 in which the positive electrode ring is welded to the positive electrode can, the assembly speed and the yield tend to be greatly reduced as compared with Comparative Example 1 in which the positive electrode ring is not used. On the other hand, in Examples 1-4, 6 in which the protrusions for positioning the positive electrode pellets are provided on the gasket, the same assembly speed and yield as in Comparative Example 1 can be achieved. That is, it is possible to suppress a decrease in productivity of the coin type lithium battery using the positive electrode ring.

In Example 5, the yield tends to be lower than that in Comparative Example 1. This, in Example 5, since a larger inside diameter D _A of the inner diameter D _B is positive ring gasket, welded cathode ring cathode can is because the problem that rides on the positive electrode pellets occurs. In Example 6, the ratio (D _A / D _B ) between the inner diameter D _{A of the} positive ring and the inner diameter D _{B of the} gasket is the same as in Example 5, but the inner diameter D _C at the tip of the positive ring and the inner diameter of the gasket Since the ratio to D _B (D _C / D _B ) was larger than Example 5, there was no problem that the ring climbed onto the pellet.

Table 2 shows the following.
In Examples 1 to 6 using the protruding portion of the gasket and the positive electrode ring, the closed circuit voltage with a discharge depth of 80% is significantly improved as compared with Comparative Example 1 without the positive electrode ring.

  Moreover, in Examples 1-6 using the protrusion part and positive electrode ring of a gasket, compared with the comparative example 2 using a positive electrode ring, the discharge depth 80% closed circuit voltage is improving greatly. Such an effect is considered to be due to the following reasons. In Comparative Example 2, since the electrolytic solution was dropped while the positive electrode pellet and the positive electrode ring were in close contact with each other in the production process, the electrolytic solution was not absorbed from the side surface of the positive electrode pellet, and the positive electrode can dropped with the electrolytic solution was removed. Since the electrolytic solution is spilled for reversal, the closed-circuit voltage is reduced by a discharge depth of 80%. On the other hand, in Examples 1-6, while providing a clearance between a positive electrode pellet and a positive electrode ring, and also eliminating the process of inverting a positive electrode pellet, the problem like the comparative example 2 mentioned above is eliminated. As a result, the closed circuit voltage with a discharge depth of 80% is improved as compared with the second comparative example.

Ratio (D _A / D _B) in Example 4 was 1.15, the ratio (D _A / D _B) of 1.10 as compared with Example 1～3,5,6 was less discharge depth 80 % Closed circuit voltage tends to decrease. This is because the ratio (D _A / D _B ) between the inner diameter D _A of the positive electrode ring and the inner diameter D _{B of the} gasket becomes too large, that is, the clearance between the positive electrode ring and the positive electrode pellet is too large. This is because the expansion increases and the expansion in the thickness direction decreases.

Although detailed description of the evaluation results is omitted, if the ratio (D _A / D _B ) is less than 0.97, the assembly speed is lower than that of Comparative Example 2. This is due to the following reason. That is, when the ratio (D _A / D _B) is less than 0.97, since the inner diameter D _B of the gasket is too large, the movable range of the positive electrode pellet becomes too wide. As a result, when the positive electrode can is put on the negative electrode cup, the positive electrode ring rides on the positive electrode pellet. Thus, when the positive electrode ring rides on the positive electrode pellet, the production line must be stopped, and the assembly speed is reduced.

Considering the evaluation results in Table 2 above, the ratio (D _A / D _B ) between the inner diameter D _{A of the} positive electrode ring and the inner diameter D _{B of the} gasket is preferably 0.97 or more and 1.10 or less. Furthermore, in consideration of the evaluation result (yield) in Table 1, the ratio (D _A / D _B ) between the inner diameter D _{A of the} positive ring and the inner diameter D _{B of the} gasket is 1.00 or more and 1.10 or less. preferable.

  In Example 6 in which the distal end portion of the peripheral wall portion of the positive electrode ring is bent outward, battery characteristics equivalent to those in Example 5 in which the peripheral wall portion of the positive electrode ring is not bent can be obtained. That is, by bending the front end portion of the peripheral wall portion of the positive electrode ring to the outside, productivity can be improved without causing deterioration in battery characteristics. The bending of the positive electrode ring is not limited to the shape of the positive electrode ring of Example 6 described above, that is, the shape in which only the tip portion is bent outward (FIG. 7B). For example, the same effect as in Example 6 can be obtained even when the entire peripheral wall portion of the positive electrode ring is bent outward (FIG. 7A).

  As mentioned above, although embodiment of this invention was described concretely, this invention is not limited to the above-mentioned embodiment, Various deformation | transformation based on the technical idea of this invention is possible.

  For example, the configurations, methods, shapes, materials, numerical values, and the like given in the above-described embodiments are merely examples, and different configurations, methods, shapes, materials, numerical values, and the like may be used as necessary.

  The configurations of the above-described embodiments can be combined with each other without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 Positive electrode can 2 Positive electrode pellet 3 Negative electrode cup 4 Negative electrode material 5 Separator 6 Gasket 7 Positive electrode ring 11 Main part 12a Protrusion part 12 Extension part 21 Joining part 22 Perimeter wall part

Claims (9)

A positive electrode can,
A negative electrode can,
Among the surfaces of the positive electrode can, a positive electrode material provided on the surface facing the negative electrode can,
Of the surface of the negative electrode can, the negative electrode material provided on the surface facing the positive electrode can,
A gasket interposed between peripheral edges of the positive electrode can and the negative electrode can;
A positive electrode ring covering the side surface of the positive electrode material,
The gasket is a battery having a plurality of projecting portions or extending portions for positioning the positive electrode material. The gasket has a ring shape,
The battery according to claim 1, wherein the plurality of projecting portions are provided on an inner peripheral side of the gasket and project toward a central portion of the negative electrode can. The gasket has a ring shape,
2. The battery according to claim 1, wherein the extending portion is uniformly extended in a ring shape from an inner periphery of the gasket toward a central portion of the negative electrode can. The positive ring is
A wall covering the side surface of the positive electrode material;
The battery according to any one of claims 1 to 3, further comprising: a joining portion joined to the positive electrode can. A side surface of the positive electrode material has an exposed region exposed from the wall;
The battery according to claim 4, wherein the plurality of projecting portions or extending portions project or extend toward an exposed region of the positive electrode material.   The battery according to any one of claims 1 to 3, wherein at least a tip portion of the wall portion of the positive electrode ring is widened outward. The ratio (D _A / D _B ) between the inner diameter D _{A of the} positive electrode ring and the inner diameter D _{B of the} gasket is in a range of 0.97 or more and 1.10 or less. battery. The ratio (D _A / D _B ) between the inner diameter D _{A of the} positive electrode ring and the inner diameter D _{B of the} gasket is in the range of 1.00 or more and 1.10 or less. battery. A step of disposing a gasket having a plurality of protruding portions or extending portions on the peripheral edge of the negative electrode can;
Positioning the positive electrode material by the plurality of protrusions, or extending portions, and placing the positive electrode material on the negative electrode can;
The negative electrode can and the positive electrode can, wherein the negative electrode can on which the positive electrode material is arranged and the positive electrode can on which the ring member is joined are overlapped so that the positive electrode material and the ring member face each other. And a step of caulking the peripheral edge of the battery.

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