JP3440870B2 - Cylindrical lithium-ion 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 cylindrical lithium ion battery, and more particularly to an electrode winding group in which a positive electrode, a negative electrode and a separator are wound in a cylindrical battery container, and the electrode winding group is connected to each electrode terminal. The present invention relates to a cylindrical lithium ion battery including a connecting portion and an electrolytic solution for controlling the internal pressure, and including an internal pressure reduction mechanism that releases gas in response to an increase in internal pressure of the battery container.

[0002]

2. Description of the Related Art A lithium ion secondary battery is mainly used as a power source for a portable device such as a VTR camera, a notebook computer, a mobile phone or the like, taking advantage of its high energy density. Inside the cylindrical lithium-ion secondary battery, both the positive electrode and the negative electrode have a strip shape in which the active material is applied to the metal foil, and the cross section is spiral so that these electrodes do not come into direct contact with the separator in between. It has a winding-type structure in which a winding group is formed by winding. Then, this winding group is housed in a cylindrical battery can that serves as a battery container.
It is sealed after injecting the electrolyte.

The external dimensions of a general cylindrical lithium-ion secondary battery are called 18650 type, diameter 18 mm,
It has a height of 65 mm and is widely used as a small-sized consumer lithium-ion battery. Lithium cobalt oxide, which is characterized by high capacity and long life, is mainly used for the positive electrode active material of the 18650 type lithium ion secondary battery, the battery capacity is about 1.3 Ah to 1.7 Ah, and the output is about 10 W. It is a degree.

On the other hand, in the automobile industry, in order to deal with environmental problems, the development of an electric vehicle without exhaust gas and a battery whose power source is completely a battery, or a hybrid using both an internal combustion engine and a battery as a power source. The development of (electric) vehicles has accelerated, and some have reached the stage of practical use. Naturally, a secondary battery serving as a power source of an electric vehicle is required to have characteristics such that high output and high energy can be obtained, and a lithium ion battery is receiving attention as a secondary battery satisfying these requirements.

[0005]

However, in the case of a lithium-ion battery, the higher the output, the more the safety tends to be emphasized, and in particular, the high-capacity, high-output battery used for a power source for electric vehicles. Especially in. In addition, since a high-capacity, high-output battery is charged with a large amount of current and discharged, it operates according to an increase in battery internal pressure during an abnormality, which is generally adopted for 18650 type lithium-ion batteries. It is difficult to provide a current cutoff mechanism (a kind of disconnection switch) in the battery structure.

In the case of an electric vehicle that carries passengers, during overcharging when the charging control system fails, when a battery crashes that may occur in an accidental collision, or when a foreign object is stabbed. Securing the safety of the battery itself when an external short circuit occurs is a minimum and very important battery characteristic. Battery safety here means that the behavior of the battery when it is exposed to abnormal conditions does not cause any physical damage to people, but it also minimizes damage to the vehicle. Means that.

In view of the above problems, it is an object of the present invention to provide a cylindrical lithium ion battery having a high capacity and a high output, but having an extremely high safety.

[0008]

In order to achieve the above object, the present invention provides an electrode winding group in which a positive electrode, a negative electrode and a separator are wound in a cylindrical battery container, and the electrode winding group is connected to each electrode terminal. In a cylindrical lithium-ion battery having a connection part and an electrolytic solution for performing internal pressure reduction mechanism that releases gas in response to an increase in internal pressure of the battery container, the positive electrode contains lithium manganese complex oxide. Active material mixture is applied, the solvent of the electrolytic solution is at least ethylene carbonate, dimethyl carbonate, diethyl carbonate and
A mixed solvent containing ethyl methyl carbonate , wherein the ethylene carbonate is 30% in the mixed volume ratio.
To 50%, the dimethyl carbonate is 15% or more,
15% or more of the diethyl carbonate,
Chill carbonate is not less than 10%, the solute of the electrolyte concentration of the electrolytic solution after the A and solute dissolved hexafluoro lithium phosphate (LiPF ₆₎ is to 0.7 mol / l
1.3 mol / l , 0.5% in the electrolyte
It is characterized in that vinylene carbonate is added in an amount of from 2.0% to 2.0% .

In the present invention, in order to secure a cylindrical lithium ion battery having a high capacity and a high output, an active material mixture containing lithium manganese oxide is applied to the positive electrode. In a cylindrical lithium-ion battery that does not have a current interruption mechanism, when exposed to the above-mentioned abnormal state, a high-current charge or high-current discharge state is maintained and gas is generated by a chemical reaction between the electrolytic solution and lithium manganese complex oxide. Generates and raises the internal pressure of the cylindrical battery container. Generally, in a cylindrical lithium ion battery, in order to prevent an increase in internal pressure of the cylindrical battery container,
For example, it has an internal pressure reduction mechanism such as a cleavage valve that cleaves at a predetermined internal pressure to release gas to the outside of the cylindrical battery container, but the solvent of the electrolytic solution is at least ethylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate.
It is a mixed solvent containing carbonate and the mixed volume ratio of ethylene carbonate is 30% to 50%.
15% or more of lu carbonate and diethyl carbonate
15% or more, ethyl methyl carbonate is 10% or more, and the solute of the electrolytic solution is lithium hexafluorophosphate (LiP).
The concentration of the electrolyte solution after dissolving the solute is 0.7 mol as F ₆ ).
/ L to 1.3 mol / L, and by using 0.5% to 2.0% of vinylene carbonate added to this electrolyte, gas is rapidly released from the internal pressure reducing mechanism. since no is very gently performed, excellent safety Rutotomoni, cylindrical lithium high output
An ion battery can be realized .

[0010]

[0011] At this time, dimethyl carbonate, is preferably not less than 50% of the mixed solvent total volume ratio of each solvent diethyl carbonate and ethyl methyl carbonate.

[0012]

DETAILED DESCRIPTION OF THE INVENTION hereinafter, for implementation in the form of a cylindrical lithium ion battery according to the present invention will be described with reference to the drawings.

<Battery manufacturing method> [Production of positive electrode plate] Manganese, which is an active material, is used in the production of the positive electrode plate.
Lithium oxide (LiMn_TwoO_Four) To 87 parts by weight of powder,
8.7 parts by weight of flake graphite (average particle size: 20
μm) and 4.3 parts by weight of polyvinylidene fluoride as a binder
Den was added to this and N-methylpyrrolidone as a dispersion solvent was added.
20 μm thick aluminum was added and kneaded
Substantially even and uniform application on both sides of foil (positive electrode current collector)
did. At this time, the width of 50
The uncoated part of mm was left. Then dry, press, cut
Width 300 mm, length 690 cm, including aluminum foil
A positive electrode plate having a thickness of 210 μm was obtained. Positive
The bulk density of the active material layer is 2.65 g / cm. ^ThreeAnd Positive
Make a notch in the part of the electrode plate that has not been applied with the slurry, and leave the notch
Was used as the lead piece. In addition, the adjacent lead pieces are 20 mm
The width of the lead pieces was 10 mm.

[Production of Negative Electrode Plate] In the production of the negative electrode plate, 8 parts by weight of polyvinylidene fluoride as a binder was added to 92 parts by weight of amorphous carbon, which is a product name of CARBOTRON P powder manufactured by Kureha Chemical Industry Co., Ltd. Then, N-methylpyrrolidone as a dispersion solvent was added thereto, and the kneaded slurry was applied to both surfaces of a rolled copper foil (negative electrode current collector) having a thickness of 10 μm. At this time, an uncoated portion having a width of 50 mm was left on one side edge in the lengthwise direction of the electrode plate.
After that, it is dried, pressed and cut to a width of 305 mm and a length of 70.
8 cm, thickness of active material coating 130 μm without rolled copper foil
m negative electrode plate was obtained. The bulk density of the negative electrode active material layer is 1.0 g
/ Cm ³ . A notch was made in the uncoated portion of the negative electrode plate in the same manner as the positive electrode plate, and the remaining notch was used as a lead piece.
In addition, adjacent lead pieces were spaced at 20 mm, and the width of the lead pieces was 10 mm.

The charging amount of the positive electrode and the negative electrode of each battery was determined as follows. The charge end potential of the positive electrode is 4.5 V (Li /
Rechargeable capacity up to Li +) and final voltage of negative electrode 0V
The rechargeable capacity up to (Li / Li + reference) was set to be the same. By the way, in the positive electrode active material, the chargeable capacity per unit weight of lithium manganate active material is 105 m.
Ah / g, lithium cobalt oxide rechargeable capacity is 155
It was mAh / g. The chargeable capacity of the negative electrode active material is 45
It was 0 mAh / g. When wound, the length of the negative electrode is greater than the length of the positive electrode so that the positive electrode does not protrude from the negative electrode in the winding direction at the innermost circumference of the winding and the positive electrode does not protrude from the negative electrode in the winding direction at the outermost circumference. I also made it 18 cm longer. In order to prevent the positive electrode active material coating portion from protruding from the negative electrode active material coating portion even in the direction perpendicular to the winding direction,
The width of the negative electrode active material applied portion was made 5 mm longer than the width of the positive electrode active material applied portion.

[Manufacture of Battery] The positive electrode plate and the negative electrode plate manufactured as described above have a thickness of 40 μm so that the two electrode plates do not come into direct contact with each other.
m polyethylene separator is sandwiched and wound. At this time, the lead pieces of the positive electrode plate and the lead pieces of the negative electrode plate are positioned on opposite end surfaces of the winding group, respectively.

As shown in FIG. 1, the lead pieces 9 led out from the positive electrode plate are deformed, and all of them are deformed from the periphery of the pole column (positive electrode external terminal 1) which is almost on the extension line of the winding group 6 axis core. Collect and contact around the circumference of the collar 7 that is overhanging integrally. After the lead piece 9 is brought into contact with the peripheral surface of the collar portion 7, the lead piece 9 and the peripheral surface of the collar portion 7 are ultrasonically welded to connect and fix the lead piece 9 to the peripheral surface of the collar portion 7.

The connecting operation between the negative electrode external terminal 1'and the lead piece 9 led out from the negative electrode plate is performed in the same manner as the above-mentioned connecting operation between the positive electrode external terminal 1 and the lead piece 9 led out from the positive electrode plate. .

After that, an insulating coating 8 is applied to the entire circumference of the flange 7 of the positive electrode external terminal 1 and the negative electrode external terminal 1 '. The insulating coating 8 also affects the entire outer peripheral surface of the winding group 6. As the insulating coating 8, an adhesive tape was used in which the base material was polyimide, and one surface of which was coated with an adhesive made of hexamethacrylate.
The adhesive tape is wound in multiple layers from the peripheral surface of the collar portion 7 to the outer peripheral surface of the winding group 6 to form the insulating coating 8. The winding group 6 is inserted into the battery container 5 by adjusting the number of windings so that the maximum diameter part of the winding group 6 becomes the insulating coating 8 existing part and making the maximum diameter slightly smaller than the inner diameter of the battery container 5. To do.

Next, a second ceramic washer 3'having a thickness of 2 mm, an inner diameter of 16 mm and an outer diameter of 25 mm, which is made of alumina and comes into contact with the back surface of the battery lid 4, has a tip as shown in FIG. And the tip of the pole column constituting the negative pole external terminal 1 '. Further, the first ceramic washer 3 is placed on the battery lid 4, and the positive electrode external terminal 1 and the negative electrode external terminal 1 ′ are respectively passed through the first ceramic washer 3. After that, the peripheral end surface of the disk-shaped battery lid 4 is fitted into the opening of the battery container 5, and the entire contact portions of both are laser-welded. At this time, the positive electrode external terminal 1 and the negative electrode external terminal 1 ′ penetrate the hole in the center of the battery lid 4 and project to the outside of the battery lid 4. And as shown in FIG. 1, it is made of alumina and has a thickness of 2
mm, an inner diameter of 16 mm, and an outer diameter of 28 mm, and a flat first ceramic washer 3 and a metal washer 11 that is smoother than the bottom surface of the nut 2 are fitted into the positive electrode external terminal 1 and the negative electrode external terminal 1'in that order. The battery lid 4 is provided with a cleaving valve 10 that cleaves in response to an increase in internal pressure of the battery. The cleavage pressure of the cleavage valve 10 was set to 13 to 18 kg / cm ² .

Next, a metal nut 2 is screwed to each of the positive electrode external terminal 1 and the negative electrode external terminal 1 ', and the battery is inserted through the second ceramic washer 3', the first ceramic washer 3 and the metal washer 11. Tighten the lid 4 between the collar portion 7 and the nut 2 to fix it. The tightening torque value at this time is 7
It was set to 0 kgf · cm. The metal washer 11 did not rotate until the tightening work was completed. In this state, the rubber (EP
The power generation element inside the battery container is shielded from the outside air by the compression of the DM) O-ring 12.

Then, a cylindrical lithium ion battery 20 is completed by injecting 0.33 liter of electrolytic solution into the battery container 5 through the liquid injection port 13 provided in the battery lid 4, and then sealing the liquid injection port. Let Cylindrical lithium-ion battery 20
Has a rated capacity of 80 Ah. It should be noted that the cylindrical lithium ion battery 20 is not provided with a current interruption mechanism that operates so as to interrupt the current in response to the increase in the internal pressure of the battery container 5.

[Electrolytic Solution] Next, the electrolytic solution injected into the battery container 5 will be described in detail.
In the electrolytic solution of the present embodiment, ethylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate are used.
Le carbonate to a mixed solution of a predetermined volume ratio hexafluoride phosphate lithium (LiPF ₆₎ was dissolved a predetermined mol / l, it was used after adding a predetermined amount of vinylene carbonate.

[0024]

[0025]

[0026]

[0027]

[0028]

[0029]

[0030]

[0031]

[0032]

[0033]

[0034]

[0035]

[0036]

[0037]

[0038]

[0039]

[0040]

[0041]

[0042]

As shown in Table 1 , in this embodiment, the electrolytic solutions of Examples 13 to 22 to which the present invention was applied and the electrolytic solutions of Comparative Examples 23 to 27 and 4 to 7 for confirming the effects of the examples were used. Each was manufactured (hereinafter, the cylindrical lithium ion battery 20 into which each of these electrolytic solutions was injected was used in Examples 13 to 22.
Batteries of Comparative Examples 23 to 27 and 4 to 7. ).
In Table 1 , D represents ethylmethyl carbonate, A is ethylene carbonate , and B is dimethylcarbocarbon.
Nate , C is diethyl carbonate , E is hexafluorophosphoric acid
Lithium and F represent vinylene carbonate .

[0044]

[Table 1]

The electrolytic solution of the battery of Example 13 was 30% by volume of ethylene carbonate (A), 25% by volume of dimethyl carbonate (B), 25% by volume of diethyl carbonate (C), and 20% by volume of ethylmethyl carbonate (D). Lithium hexafluorophosphate (E) was dissolved in a mixed solvent to prepare a solution of 0.1.
8 mol / liter, vinylene carbonate (F)
1.0% was added (the same applies to the electrolytic solutions of the batteries of Examples and Comparative Examples described below in Table 1 ). The batteries of Comparative Examples 23 to 27 and 4 to 7 are the same as those of Examples 13 to
Like the battery of No. 22 , each has a rated capacity of 80 Ah.

Next, for each of the batteries thus manufactured, the following tests 1 and 2 were conducted. The test results of Test 1 and Test 2 are shown in Table 2 below. [Test 1] room
Charge at 4.2V constant voltage, limited current 80A for 4 hours at high temperature
After 1 hour rest, 80A, 160A, 240A
Discharge at a constant current for 10 seconds, and change the voltage at the 10th second
On the axis, the current is plotted against the horizontal axis, and a linear approximation is made. This
And the voltage value 2.8 where the straight line intersects the voltage 2.8V
The product of V and the output (kW). [Test 2] 80 at room temperature
The battery behavior was observed by continuously charging at A constant current. The phenomenon is
After the cleaving valve is cleaved, gas release occurs. The extent of this gas release
In order to show the degree, weigh the battery after the phenomenon
Shown as a percentage of the previous weight. Also, after releasing the gas,
Check if the pond container is deformed.

[0047]

[Table 2]

In all the batteries of this embodiment,
As a result of the test 2, after the cleaving valve was cleaved, only a gentle discharge of gas was observed, the battery was not deformed, the battery weight was as high as 81 to 84%, and a high maintenance rate was secured, and the battery contents were hardly discharged. The behavior was extremely gentle. Real施例13-22
As a result of the test 1, the battery of No. 1 obtained a high output of 5.1 to 5.4 kW.

On the other hand, in the battery of Comparative Example 23, the solvent composition of the electrolytic solution contained less than 15% by volume of dimethyl carbonate (B), and as a result of Test 1, the output decreased to 4.6 kW.

In the battery of Comparative Example 24, the solvent composition of the electrolytic solution contained less than 10% by volume of ethylmethyl carbonate (D), and as a result of Test 1, the output decreased to 4.7 kW.

In the battery of Comparative Example 25, the total amount of dimethyl carbonate (B), diethyl carbonate (C) and ethyl methyl carbonate (D) was 5 in the solvent composition of the electrolytic solution.
It is less than 0% by volume, and as a result of Test 1, the output is 4.4.
It was lowered to kW.

In the battery of Comparative Example 26, the concentration of the electrolytic solution after dissolving lithium hexafluorophosphate (E) was set to 0.6 mol / liter, and as a result of Test 1, the output decreased to 4.4 kW.

In the battery of Comparative Example 27, the amount of vinylene carbonate (F) added exceeded 2%, and as a result of Test 1, the output decreased to 4.7 kW.

[0054] In the battery of specific Comparative Examples 4, ethylene carbonate (A) is below 30 vol%, although the results 5.2kW and high power test 1 is obtained, cleavage valve cleavage results of Test 2 After that, the gas was relatively violently discharged from the cleaving valve along with the discharge of a part of the battery contents, and the battery weight after the phenomenon was 72%, which shows that the degree of gas discharge is large.

In the battery of Comparative Example 5, the output of Test 1 was as high as 5.2 kW, but the solvent composition of the electrolytic solution contained less than 15% by volume of diethyl carbonate (C). As a result, after the cleaving valve was cleaved, gas was relatively violently discharged from the cleaving valve with the release of a part of the battery contents, and no deformation of the battery container was observed. From 71%, it can be seen that the degree of gas release is large.

In the battery of Comparative Example 6, since the concentration of the electrolytic solution after dissolving lithium hexafluorophosphate (E) was 1.6 mol / liter, the result of Test 1 was a high output of 5.7 kW. However, as a result of Test 2, after the cleaving valve was cleaved, gas was relatively violently discharged from the cleaving valve along with the release of a part of the battery contents, and the battery weight after the phenomenon was 70%.
In addition, since the battery container was found to be slightly bulged, it was found that the degree of gas release was large.

In the battery of Comparative Example 7, the amount of vinylene carbonate (F) added was less than 0.5%, and 5.6k.
Although a high output of W was obtained, as a result of Test 2, after the cleaving valve was cleaved, gas was relatively violently discharged from the cleaving valve accompanied by partial discharge of the battery contents. The weight was 70%. In addition, since the battery container was found to be slightly bulged, it was found that the degree of gas release was large.

Therefore, the thirteenth embodiment of the present embodiment
In each of the batteries No. 22 and No. 22 , the solvent of the electrolytic solution was a mixed solvent of ethylene carbonate (A), dimethyl carbonate (B), diethyl carbonate (C) and ethyl methyl carbonate (D). Ethylene carbonate (A) 30% or more, diethyl carbonate (C) 15% or more, the solute of the electrolytic solution 6
The concentration of the electrolyte solution after dissolving lithium hexafluorophosphate (E) as lithium fluorophosphate (E) was set to 1.5 mol / liter or less, and vinylene carbonate (F) was added to 0.5
% And added as an electrolytic solution, it has a high capacity and a high output, but the behavior is extremely gentle when the battery is exposed to abnormal conditions, and it can be said that the battery has excellent safety. . In particular, a battery as a power source for an electric vehicle is required to have relatively high capacity and high output characteristics.
Batteries with high capacity, high output, and extremely high safety, such as the battery No. 22 , are suitable as a power source for electric vehicles.

Further, as described above, the batteries of Examples 13 to 22 of the present embodiment can obtain a high output of 5.1 kW or more, but in all of these batteries, the mixing volume ratio of the mixed solvent was ethylene carbonate ( A) 30% to 50%, dimethyl carbonate (B) 15% or more, diethyl carbonate (C) 15% or more, ethyl methyl carbonate (D) 1
0% or more, the concentration of the electrolytic solution after dissolving the lithium hexafluorophosphate (E) is 0.7 to 1.3 mol / liter, and vinylene carbonate (F) is 0.5 to 2.0 in this electrolytic solution.
% To make an electrolytic solution. At this time, as apparent from the batteries of Example 17 and Comparative Example 25, the total volume ratio of each solvent of dimethyl carbonate (B), diethyl carbonate (C) and ethyl methyl carbonate (D) was 50% or more of the mixed solvent. It is preferable that

In the above embodiment, the cylindrical lithium ion battery having no current interruption mechanism has been exemplified, but the present invention is not limited by the presence or absence of the current interruption mechanism. Even with a battery having a current cutoff mechanism, it is assumed that the current will not be cut off by the current cutoff mechanism when the battery is exposed to an abnormal state as described above, and therefore the safety of the battery can be improved by applying the present invention. It can be further improved.

In the above embodiment, the large-sized secondary battery used as the power source for the electric vehicle is exemplified.
Needless to say, the size and capacity of the battery are not limited.

In the above embodiment, the insulating coating 8
In, the substrate is a polyimide, using an adhesive tape coated with an adhesive consisting of hexamethacrylate on one side, but not limited to this, for example, the substrate is a polyolefin such as polypropylene or polyethylene, A pressure-sensitive adhesive tape having an acrylic pressure-sensitive adhesive such as hexamethacrylate or butyl acrylate coated on one or both sides thereof, or a tape made of polyolefin or polyimide not coated with a pressure-sensitive adhesive can be preferably used.

Furthermore, in the above embodiment, lithium manganate was used for the positive electrode and lithium carbon for the negative electrode for the lithium ion battery, but the method for producing the battery of the present invention is not particularly limited, and the binder is used. Any of the commonly used negative electrode active materials can be used. However, in order to ensure high capacity, high output, and safety, it is necessary to use lithium-manganese composite oxide as the positive electrode active material, not lithium-cobalt composite oxide or lithium-nickel composite oxide. Is.

Although polyvinylidene fluoride is used as the binder in the above embodiments, other electrode active material binders for lithium ion batteries include Teflon, polyethylene, polystyrene, polybutadiene, butyl rubber, nitrile. Polymers such as rubber, styrene / butadiene rubber, polysulfide rubber, nitrocellulose, cyanoethylcellulose, various latexes, acrylonitrile, vinyl fluoride, vinylidene fluoride, propylene fluoride and chloroprene fluoride, and mixtures thereof are available.

Further, as the positive electrode active material for lithium ion batteries other than those shown in the above embodiments, a material capable of inserting and releasing lithium, and a lithium manganese compound oxide into which a sufficient amount of lithium has been inserted in advance is used. However, lithium manganate having a spinel structure or a material in which a part of manganese or lithium in the crystal is replaced or doped with an element other than these may be used.

The application of the present invention is not limited even if a negative electrode active material for lithium ion batteries other than those shown in the above embodiments is used. For example, natural graphite, various artificial graphite materials, and carbonaceous materials such as coke may be used.
The shape of the particles is not particularly limited, and may be scaly, spherical, fibrous, lumpy, or the like.

[0067]

As described above, according to the present invention,
In a cylindrical lithium-ion battery equipped with an internal pressure reduction mechanism that releases gas, in order to prevent an increase in internal pressure of the cylindrical battery container, for example, a cleavage valve that cleaves at a predetermined internal pressure to release the gas to the outside of the cylindrical battery container. Although it has a mechanism to reduce internal pressure, the solvent of the electrolytic solution should be at least ethylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl ether.
30% to 50% of ethylene carbonate in a mixture volume ratio a mixed solvent containing Le carbonate, di
More than 15% methyl carbonate, diethyl carbonate
15% or more, ethyl methyl carbonate 10% or more
Above , the solute of the electrolyte is lithium hexafluorophosphate (LiP
The concentration of the electrolyte solution after dissolving the solute is 0.7 mol as F ₆ ).
/ L to 1.3 mol / L, and by using 0.5% to 2.0% of vinylene carbonate added to this electrolyte, gas can be rapidly released from the internal pressure reducing mechanism. since no is very gently performed, excellent safety Rutotomoni, cylindrical lithium high output
The effect that an ion battery can be realized can be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a cylindrical lithium secondary battery according to a first embodiment of the present invention.

[Explanation of symbols]

1 Positive external terminal 1'negative electrode external terminal 2 nuts 3 First ceramic washer 3'second ceramic washer 4 Battery lid 5 Battery case (cylindrical battery case) 6 winding group (electrode winding group) 7 collar part 8 Insulation coating 9 lead pieces 10 Cleavage valve 11 metal washers 12 O-ring 13 Injection port 20 Cylindrical lithium-ion battery

─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP 2000-138071 (JP, A) JP 5-211070 (JP, A) JP 5-13088 (JP, A) JP 5-283104 (JP, A) JP-A-9-63642 (JP, A) JP-A-8-45545 (JP, A) JP-A-8-96852 (JP, A) JP-A-7-122296 (JP, A) (JP-A) 58) Fields investigated (Int.Cl. ⁷ , DB name) H01M 10/40 H01M 2/12

Claims (2)

(57) [Claims] 1. A cylindrical battery container, which contains therein an electrode winding group in which a positive electrode, a negative electrode, and a separator are wound, a connecting portion for connecting the electrode winding group to each electrode terminal, and an electrolytic solution. In a cylindrical lithium-ion battery having an internal pressure reduction mechanism that releases gas according to an increase in internal pressure of the container, an active material mixture containing lithium manganese oxide is applied to the positive electrode, and the solvent of the electrolytic solution is at least Ethylene carbonate, dimethyl carbonate, diethyl carbonate and
A mixed solvent containing ethyl methyl carbonate , wherein the ethylene carbonate is 30% in the mixed volume ratio.
To 50%, the dimethyl carbonate is 15% or more,
15% or more of the diethyl carbonate,
Chill carbonate is not less than 10%, the solute of the electrolyte concentration of the electrolytic solution after the A and solute dissolved hexafluoro lithium phosphate (LiPF ₆₎ is to 0.7 mol / l
1.3 mol / l , 0.5% in the electrolyte
A cylindrical lithium-ion battery, to which 2.0 to 2.0% of vinylene carbonate is added. 2. The cylindrical lithium ion battery according to claim 1 , wherein a total volume ratio of the respective solvents of dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate is 50% or more in the mixed solvent.