JP4862528B2 - Electrochemical element - Google Patents

Description

  The present invention relates to a sealed electrochemical device, and more particularly to an insulating plate for a high energy density electrochemical device.

  Development of new high-capacity active materials for electrochemical devices, particularly non-aqueous electrolyte secondary batteries with high energy density that can be charged and discharged, is being promoted with the aim of further increasing energy density. Specifically, the positive electrode active material is being developed from lithium cobalt oxide to lithium nickel oxide, and the negative electrode active material is being developed from graphite to an alloy material containing silicon, tin, and the like.

  Non-aqueous electrolyte secondary batteries using these active materials usually have a sealed structure in which an electrode group in which a positive electrode and a negative electrode are stacked via a separator is housed in a case, and the opening of the case is sealed with a sealing plate. ing. Further, by connecting positive and negative leads led from the electrode group to a sealing plate and a case having a terminal function, the sealing plate and the case serve as either positive or negative terminals. When such a sealed structure is used, it is necessary to provide two mechanisms described below. The first mechanism is that when the non-aqueous electrolyte secondary battery is abnormally used, for example, when the internal pressure in the case reaches a predetermined pressure as a function of discharging the gas generated when stored at an abnormally high temperature to the outside of the case. An operating exhaust valve is built in the sealing plate. In the second mechanism, an insulating plate is provided between the electrode group and the sealing plate so that the electrode group and the sealing plate do not come into contact with each other. This insulating plate is made of a polyolefin resin such as polyethylene resin or polypropylene resin, or an insulating plate in which a glass fiber as a skeleton material and a thermosetting resin material such as a phenol resin containing an inorganic additive are laminated. It has been proposed (see, for example, Patent Document 1).

In addition, in order to prevent the electrode group from being deformed by the abnormally generated gas and restricting the gas flow path to the exhaust valve of the sealing plate, the insulating plate suppresses the deformation of the group, and 500 ° C. Have proposed an insulating plate having a withstand pressure that can withstand an internal pressure of 1 kgf / mm ² or more (see, for example, Patent Document 2).
JP 2002-231314 A JP 2000-348771 A

  When the internal pressure suddenly increases in the electrochemical device, the electrode group is pushed up to the sealing plate side by the internal pressure, and the insulating plate provided between the electrode group and the sealing plate is deformed together with the electrode group and is built in the sealing plate. If the exhaust valve is deformed, the exhaust valve does not operate well, and the gas discharge efficiency decreases. Therefore, in order to efficiently guide the gas generated in the electrochemical element to the sealing plate, the insulating plate needs to have at least one aperture.

  In addition, the insulating plate is made of a polyolefin resin such as polyethylene resin or polypropylene resin, or a glass cloth serving as a skeleton material and a thermosetting resin material such as a phenol resin containing an inorganic additive are laminated, It can be manufactured by injection molding, molding or cutting. However, when the glass cloth and the thermosetting resin are formed in a laminated structure, it is preferable that the glass cloth and the thermosetting resin are manufactured by punching from the viewpoint of reducing the production cost.

By the way, when an internal pressure rises with a rapid rise in temperature in an electrochemical element, an insulating plate (for example, as in Patent Document 1) provided between an electrode group and a sealing plate has high heat. It is deformed by the gas pressure and shuts off the gas flow path for discharging from the exhaust valve of the sealing plate to the outside of the electrochemical element. In order to prevent this, it is necessary to increase the opening area of the insulating plate.

  An electrochemical element using a high-capacity active material and having a high energy density has a remarkable gas amount and gas flow rate generated during abnormal use. In order to withstand the amount of gas and the gas flow rate, it is necessary to increase the aperture area and secure the gas exhaust path in order to improve the exhaust efficiency of the insulating plate. On the other hand, if the aperture area is increased, there is a possibility that the space between the end face of the outer shape and the end face of the aperture becomes narrow.

  If the gap between the end face of the outer shape and the end face of the hole is narrowed in order to increase the opening area of the insulating plate and secure the gas exhaust path, the damage to the insulating plate due to the shear stress during punching is The gap between the end face of the outer shape and the end face of the opening is larger than that of the wide insulating plate. As a result, when the insulating plate is made by punching, it is easy to break and the productivity is lowered. Furthermore, compared to the case where an insulating plate having the same shape is manufactured by cutting, injection molding, or molding, the insulating plate is manufactured by punching due to the shear stress at the time of punching. In the insulating plate 1, the glass fiber as the skeleton material is broken, or the interlayer between the laminated portions of the glass fiber and the phenol resin is peeled off. Therefore, the skeleton material for ensuring the strength does not play its role, and the strength of the insulating plate is greatly reduced. Thus, it has a new problem.

  The present invention has been made in view of the above problems, and even when a high energy density electrochemical element is abnormally used, it is efficient to the outside of the electrochemical element without blocking the gas flow path inside the electrochemical element. An object of the present invention is to provide an electrochemical device that can exhaust gas.

The electrochemical element of the present invention is an electrochemical element in which an electrode group in which a positive electrode and a negative electrode are laminated via a separator is housed in a case having an opening, and the opening is sealed with a sealing plate,
The sealing plate has an exhaust valve having a function of releasing the pressure in the electrochemical element to the outside of the electrochemical element when the internal pressure of the electrochemical element reaches a predetermined pressure.
Having an insulating plate between the electrode group and the sealing plate;
The insulating plate is made of a thermosetting resin, includes glass fiber as a skeleton material, and has at least one hole.
The glass fiber is parallel to a line passing through the maximum outer diameter from one end surface to the other end surface of the insulating plate, and one continuous cut from the one end surface to the other end surface of the insulating plate is within 60% of the radius from the center. It is characterized in that there is at least one place that passes through without any problem.

The insulating plate of the electrochemical element of another invention is made of a thermosetting resin, includes a metal fiber as a skeleton material, and has at least one hole.
The metal fiber is parallel to a line passing through the maximum outer diameter from one end surface to the other end surface of the insulating plate, and one continuous cut from the one end surface to the other end surface of the insulating plate is within 60% of the radius from the center. It is characterized in that there is at least one place that passes through without any problem.

The insulating plate of the electrochemical element of another invention is made of a thermosetting resin, includes carbon fiber as a skeleton material, and has at least one hole.
The carbon fiber is parallel to a line passing through the maximum outer diameter from one end surface to the other end surface of the insulating plate, and one continuous cut from the one end surface to the other end surface of the insulating plate is within 60% of the radius from the center. It is characterized in that there is at least one place that passes through without any problem.

An insulating plate of an electrochemical element according to another invention is made of a thermosetting resin, includes at least one of glass fiber, metal fiber, and carbon fiber as a skeleton material, and has at least one aperture. And
The fiber is parallel to a line passing through the maximum outer diameter from one end surface to the other end surface of the insulating plate, and one continuous cut from the one end surface to the other end surface of the insulating plate is within 60% of the radius from the center. It is characterized in that there is at least one place that passes through.

  According to the present invention, even when a high energy density electrochemical element is abnormally used, without blocking the gas flow path inside the electrochemical element, without blocking the gas flow path inside the electrochemical element, An electrochemical element capable of efficiently exhausting gas to the outside of the electrochemical element can be provided.

The first invention is an electrochemical device in which an electrode group in which a positive electrode and a negative electrode are laminated via a separator is housed in a case having an opening, and the opening is sealed with a sealing plate,
The sealing plate has an exhaust valve having a function of releasing the pressure in the electrochemical element to the outside of the electrochemical element when the internal pressure of the electrochemical element reaches a predetermined pressure.
Having an insulating plate between the electrode group and the sealing plate;
The insulating plate is made of a thermosetting resin, includes glass fiber as a skeleton material, and has at least one hole.
The glass fiber is parallel to a line passing through the maximum outer diameter from one end surface to the other end surface of the insulating plate, and one continuous cut from the one end surface to the other end surface of the insulating plate is within 60% of the radius from the center. It is characterized in that there is at least one place that passes through without any problem.

  As a manufacturing process of an insulating plate, a plate made of glass fiber and a thermosetting resin as a base of the insulating plate is used, a step of punching a hole through which a gas generated during abnormal use passes, and an insulating plate having a predetermined outer shape It consists of a process of punching into a shape. Such a process is desirable from the viewpoint of productivity and quality maintenance. The reason is that, for example, when the hole is to be punched after being punched into a predetermined outer shape, the die structure becomes complicated and the productivity is lowered in order to precisely determine the position of the hole and punch the hole. Because. The method of punching into the predetermined outer shape after punching out the opening portion of the insulating plate is the final shape of the insulating plate at the time of punching into the predetermined outer diameter. For this reason, from the viewpoint of productivity, it is desirable that the insulating plate is dropped downward from the mold after being punched into a predetermined outer diameter shape. When the punching process is performed, the material that is the base of the insulating plate on which the glass fibers are laminated is subjected to shear stress from the upper die while being sandwiched between the material presser and the lower die. Since the product pushed from the upper die is not supported from below the upper die, it is deformed so as to be torn off. For this reason, the material in the vicinity of the mold of the product may be peeled off between the layers of the laminated portion.

  When the hole area is widened to improve the gas exhaust efficiency, the gap between the end face of the outer shape and the end face of the hole becomes narrow, and the shearing stress during punching process causes lamination of glass fiber and thermosetting resin. Delamination occurs in the part, or the glass fiber is broken. Therefore, the insulating plate is easily damaged in terms of strength. The glass fiber is parallel to a line passing through the maximum outer diameter from one end surface to the other end surface of the insulating plate, and one continuous cut from the one end surface to the other end surface of the insulating plate is within 60% of the radius from the center. If there is at least one passing portion, it is difficult to receive damage due to shear stress during the punching process, so that the insulating plate in the vicinity of the mold is hardly peeled between the layers of the laminated portion.

  If the glass fiber is present at a position larger than 60%, the glass fiber length is shortened, so that the shear stress applied per length is increased, and the glass fiber is easily damaged. Therefore, by arranging the glass fiber within 60%, the mechanical strength of the insulating plate can be maintained and the gas flow path can be secured.

The glass fiber diameter is preferably 4 to 20 μm from the viewpoint of strength, compoundability, price, and the like.
When the glass fiber diameter is smaller than 4 μm, there is a possibility of breaking by shearing stress at the time of punching the insulating plate, which is not preferable from the viewpoint of strength. When the glass fiber diameter is larger than 20 μm, the density of the glass fiber does not increase and it is difficult to increase the strength. Next, a method for producing a plate in which glass fibers and a phenol resin are laminated (hereinafter abbreviated as a glass phenol laminated plate) will be briefly described. First, a prepreg in which a glass fiber is impregnated with a phenol resin is produced, and a predetermined number of the prepregs are alternately laminated so that the direction of the glass fiber is 45 ° to 135 °, followed by heating and pressing. In the case of an electrochemical element for consumer driving power supply, 2 to 5 sheets may be laminated alternately to ensure the effective volume of the battery, and the thickness of the laminated sheet may be 0.1 to 1.0 mm. In the case of an electrochemical element using a positive energy active material having a high energy density, for example, in the case of a so-called 18650 size having a diameter of 18 mm and a height of 65 mm, a thickness of 0.2 to 0.8 mm is preferable. In the case of an electrolytic chemical element for use in a driving power source such as a driving power source for an automobile or a housing facility such as an elevator, it is preferable to stack them alternately in accordance with the size of the electrochemical element. In this way, by alternately laminating the glass fibers so that the direction of the glass fibers is 45 ° to 135 °, a stronger laminate can be obtained in which the directions of the glass fibers are aligned in the same direction. Further, when the number of laminated sheets is an odd number of 3 or more, it is preferable from the viewpoint of strength to alternately laminate the glass fiber directions at 45 °. When the number of layers is two, it is preferable from the viewpoint of strength to laminate the glass fibers at 90 °. When the number of laminated layers is an even number of 4 or more, it is preferable from the viewpoint of strength to alternately laminate the glass fiber directions at 45 °. Moreover, it is preferable to laminate | stack alternately the direction of glass fiber at 90 degrees from a viewpoint of the ease of manufacture. From the above, since either the strength or the ease of manufacture of the insulating plate is selected, it is preferable to determine it according to the performance required for the electrochemical element.

  Glass fibers are roughly classified into short fibers and long fibers. Glass fibers are often used for building materials such as heat insulating materials mainly as glass wool. On the other hand, long fibers are thread-like and have a long fiber length, and are often used as industrial materials. When glass fibers are used as the skeleton material of the insulating plate, it is preferable to use thread-like long fibers.

  Examples of the glass fiber material include soda glass, lead glass, borosilicate glass, and the like, but from the viewpoint of cost, soda glass is preferable.

The insulating plate of the second invention is made of a thermosetting resin, includes a metal fiber as a skeleton material, and has at least one opening,
The metal fiber is parallel to a line passing through the maximum outer diameter from one end surface to the other end surface of the insulating plate, and one continuous cut from the one end surface to the other end surface of the insulating plate is within 60% of the radius from the center. It is characterized in that there is at least one place that passes through without any problem.

The insulating plate of the third invention is made of a thermosetting resin, includes carbon fiber as a skeleton material, and has at least one hole.
The carbon fiber is parallel to a line passing through the maximum outer diameter from one end surface to the other end surface of the insulating plate, and one continuous cut from the one end surface to the other end surface of the insulating plate is within 60% of the radius from the center. It is characterized in that there is at least one place that passes through without any problem.

The insulating plate of the fourth invention is made of a thermosetting resin, includes at least one of glass fiber, metal fiber, and carbon fiber as a skeleton material, and has at least one aperture.
The fiber is parallel to a line passing through the maximum outer diameter from one end surface to the other end surface of the insulating plate, and one continuous cut from the one end surface to the other end surface of the insulating plate is within 60% of the radius from the center. It is characterized in that there is at least one place that passes through.

When the skeletal material is made of metal fiber or carbon fiber, the fiber diameter and prepreg have a fiber direction of 45 ° to 1 °.
The same applies to the case where a predetermined number of sheets are alternately laminated so as to be 35 °. In the case of an electrochemical element for consumer driving power supply, 2 to 5 sheets may be laminated alternately to ensure the effective volume of the battery, and the thickness of the laminated sheet may be 0.1 to 1.0 mm. In the case of an electrochemical element using a positive energy active material having a high energy density, for example, in the case of a so-called 18650 size having a diameter of 18 mm and a height of 65 mm, a thickness of 0.2 to 0.8 mm is preferable. In the case of an electrolytic chemical element for use in a driving power source such as a driving power source for an automobile or a housing facility such as an elevator, it is preferable to stack them alternately in accordance with the size of the electrochemical element.

  Further, when the number of laminated sheets is an odd number of 3 or more, it is preferable from the viewpoint of strength to alternately laminate the glass fiber directions at 45 °. When the number of layers is two, it is preferable from the viewpoint of strength to laminate the glass fibers at 90 °. When the number of laminated layers is an even number of 4 or more, it is preferable from the viewpoint of strength to alternately laminate the glass fiber directions at 45 °. Moreover, it is preferable to laminate | stack alternately the direction of glass fiber at 90 degrees from a viewpoint of the ease of manufacture. From the above, since either the strength or the ease of manufacture of the insulating plate is selected, it is preferable to determine it according to the performance required for the electrochemical element.

  Metal fibers and carbon fibers are better in terms of strength than glass fibers. Moreover, the cut cross section of a metal fiber, carbon fiber, and glass fiber is exposed at the time of stamping. Therefore, in the case of an electrically conductive metal fiber or carbon fiber, there is a possibility of short-circuiting when it comes into contact with a metal part such as a case or a lead constituting the electrochemical element. In detail, the outer peripheral end face of the insulating plate is in contact with the case that also serves as the external terminal of the electrochemical element, and the lead drawn from the electrode group is the opposite pole to the case that also serves as the external terminal. When the lead is passed through the opening, the end surface of the opening of the insulating plate comes into contact with the lead. For this reason, it is necessary to insulate at least one of the end surface of the outer periphery of the insulating plate or the end surface of the opening portion of the insulating plate. As a method for the insulation treatment, it is preferable to insulate by covering the outer periphery of the insulating plate and the end face of the opening with a resin.

  Although glass fiber, metal fiber, and carbon fiber are mentioned as the skeleton material, it is preferable to use glass fiber alone from the viewpoint of insulation.

  Examples of the nonaqueous electrolyte secondary battery are shown below, but the electrochemical device of the present invention is not limited to these examples.

  A method for manufacturing the negative electrode, the positive electrode, the electrode group, the insulating plate, and the nonaqueous electrolyte secondary battery will be described in detail below. The insulating plate will be described in the case where glass fiber is used alone as the skeleton material, the glass fiber direction is 90 °, and the number of laminated sheets is three.

(Negative electrode)
Dispersion solution in which 96 parts by weight of bulk artificial graphite (manufactured by Hitachi Chemical Co., Ltd., trade name: MAG-D) as a negative electrode active material and styrene butadiene rubber (hereinafter abbreviated as SBR) as a binder are dispersed in water. 3 parts by weight of a solid content ratio, 1 part by weight of carboxymethyl cellulose (hereinafter abbreviated as CMC) (made by Daiichi Kogyo Seiyaku Co., Ltd.) as a thickener, and an appropriate amount of water are mixed together for a negative electrode mixture A paste was prepared. This paste is applied to both sides of a current collector (thickness 10 μm) made of copper (hereinafter abbreviated as Cu) foil, and after drying, rolled to a thickness of 170 μm to obtain dimensions of 58 mm width and 600 mm length. The negative electrode was obtained by cutting.

(Positive electrode)
93 parts by weight of lithium cobaltate (hereinafter abbreviated as LiCoO ₂ ) powder as a positive electrode active material and 4 parts by weight of acetylene black (hereinafter abbreviated as AB) as a conductive agent were mixed. To the obtained powder, an N-methyl-2-pyrrolidone (hereinafter abbreviated as NMP) solution of polyvinylidene fluoride (hereinafter abbreviated as PVDF) as a binder (manufactured by Kureha Chemical Industry Co., Ltd., product number: # 1320). ) Was mixed to a solid content ratio of 3 parts by weight. An appropriate amount of NMP was added to the obtained mixture to prepare a positive electrode mixture paste. This paste was applied to both sides of a current collector (thickness 15 μm) made of aluminum (hereinafter abbreviated as AL) foil, dried and then rolled to a thickness of 180 μm, and further sufficiently dried at 85 ° C., The positive electrode A was obtained by cutting into a width of 57 mm and a length of 550 mm.

In addition, LiCo _0.2 Ni _0.8 O ₂ is used as the active material, the amount applied to the AL foil is reduced, rolling is performed slowly, and the theoretical capacity and thickness per unit area are the same as those of the positive electrode A, except that it is the same as the positive electrode A. A positive electrode B was prepared according to the following formulation.

(Electrode group)
An electrode having a diameter of 17.6 mm and a height of 60 mm is obtained by winding the positive electrode A and the above-described negative electrode into a cylindrical shape via a separator (manufactured by Celgard Co., Ltd., product number: # 2320, thickness 0.02 mm). Group A (theoretical capacity: 2550 mAh) was prepared. Moreover, the electrode group B was produced using the positive electrode B in the same manner as the electrode group A.

(Insulating plate)
The insulating plate was formed by punching a laminated plate in which glass fibers were laminated as follows.

  Glass fibers (diameter 8 μm) as a skeleton material are bundled in a diameter of 0.18 mm and arranged at intervals of 0.6 mm, impregnated with a thermosetting resin phenolic resin and dried to form a sheet, and three of these are laminated. . What laminated three sheets alternately so that a glass fiber direction might turn to 90 degrees was heat-pressed, and what adjusted thickness to 0.5 mm was used as the laminated sheet. The heating temperature at this time is preferably 150 to 200 ° C., the applied pressure is 3 to 7 MPa, and the time is preferably 60 to 150 minutes.

  When punching the opening portion of the insulating plate, the glass fiber is parallel to a line passing through the maximum outer diameter from one end surface to the other end surface of the insulating plate, the center is symmetrical, and the distance from the center is 30% of the radius. In the position, one piece from the one end surface to the other end surface of the insulating plate is passed continuously without interruption (insulating plate A), the glass fiber is the maximum outside from the one end surface of the insulating plate to the other end surface Parallel to the line that passes through the diameter, the distance from the center is 30% of the radius, and one end of the insulating plate passes from one end surface to the other end without interruption (insulating plate B), glass The fiber is parallel to a line passing through the maximum outer diameter from one end surface to the other end surface of the insulating plate, symmetrically about the center, at a position 60% of the radius from the center, and from the one end surface to the other end surface of the insulating plate, 1 2 places that pass through each other without interruption (insulation) C) The glass fiber is parallel to the line passing through the maximum outer diameter from one end surface to the other end surface of the insulating plate, and the distance from the center is 60% of the radius, from one end surface to the other end surface of the insulating plate. In this continuous passage (insulating plate D), the glass fiber is parallel to a line passing through the maximum outer diameter from one end surface to the other end surface of the insulating plate, and the distance from the center is 60 of the radius. % And 70% of the insulation plate are passed from one end surface to the other end surface without interruption (insulation plate E), glass fiber from one end surface of the insulation plate to the other. Parallel to the line passing through the maximum outer diameter to the end face, symmetrically about the center, passing through the center of the insulation plate at a position where the distance from the center is 70% of the radius. (Insulating plate F), glass fiber is one of the insulating plates Parallel to the line that passes through the maximum outer diameter from the surface to the other end surface, the distance from the center is 70% of the radius so that it passes continuously from one end surface of the insulating plate to the other end surface without interruption. 8 types of insulating plates (insulating plate G) and those in which no glass fiber passed continuously from one end surface to the other end surface of the insulating plate (insulating plate H) were prepared.

(Non-aqueous electrolyte secondary battery)
After the electrode group A was stored in a cylindrical case made of iron having a diameter of 18.30 mm, an inner diameter of 17.85 mm, and a height of 68 mm, a negative electrode lead protruding from the lower surface of the electrode group A was welded to the bottom surface of the case. Furthermore, an insulating plate A (battery AA), an insulating plate B (battery AB), an insulating plate C (battery AC), an insulating plate D (battery AD), an insulating plate E (battery AE), an insulating plate are provided on the upper surface of the electrode group A. F (battery AF), insulating plate G (battery AG) and insulating plate H (battery AH) are arranged, and a positive electrode lead protruding from the upper surface of electrode group A is passed through the holes of these insulating plates, and the operating pressure is 14 It welded to the sealing board which incorporated the 7MPa exhaust valve.

  Moreover, after accommodating the electrode group B in the same case as the batteries AA to AG, the negative electrode lead protruded from the lower surface of the electrode group B was welded to the bottom surface of the case. Furthermore, an insulating plate A (battery BA), an insulating plate B (battery BB), an insulating plate C (battery BC), an insulating plate D (battery BD), an insulating plate E (battery BE), an insulating plate are formed on the upper surface of the electrode group B. F (battery BF), insulating plate G (battery BG) and insulating plate H (battery BH) are arranged, and the positive electrode lead protruding from the upper surface of electrode group A is passed through the holes of these insulating plates, and the operating pressure is 14 It welded to the sealing board which incorporated the 7MPa exhaust valve.

Lithium hexafluorophosphate (hereinafter abbreviated as LiPF ₆ ) in a solution obtained by mixing ethylene carbonate (hereinafter abbreviated as EC) and ethyl methyl carbonate (hereinafter abbreviated as EMC) at a volume ratio of 1: 3 as a non-aqueous solvent. Was dissolved at 1.2 mol / L to prepare a non-aqueous electrolyte. After reducing the diameter of the upper part of the case by machining, the prepared nonaqueous electrolyte was injected from the upper part of the case, and a sealing plate was placed on the upper part of the case and sealed with caulking. In this way, a non-aqueous electrolyte secondary battery was produced. These were designated as batteries AA to AH and BA to BH.

  FIG. 1 shows a schematic diagram showing an example of the configuration of the electrochemical device of the present invention, and FIG. 2 shows a schematic diagram showing an example of an opening of a case before sealing with a sealing plate. After the electrode group 3 in which the positive electrode and the negative electrode are laminated via the separator is housed in the case 4, the insulating plate 2 is disposed on the electrode group 3 and sealed with the sealing plate 1. An element is configured. The insulating plate 2 is provided with openings 5a and 5b. Since the openings 5a and 5b provided in the insulating plate 2 serve as escape paths for the gas suddenly generated unexpectedly, the gas is easily guided smoothly toward an exhaust valve (not shown) built in the sealing portion 1. .

  These batteries were charged with a constant current at a constant current of 500 mA until the final voltage of the battery reached 4.1 V, and a constant current discharge with a constant current of 500 mA and a final voltage of 3.0 V was repeated twice. Thereafter, the strength test of the insulating plate, the confirmation test of the difference in behavior of gas generation, and the operation check test of the exhaust valve at the time of gas generation were evaluated. The evaluation results are summarized in Table 1. The test methods for each evaluation are shown below.

(Insulation plate strength test)
Pull out 5 pieces of each insulation plate, place the insulation plate in a container with an inner diameter of 18 mm and a hole diameter of 15.5 mm as shown in Fig. 4, push the insulation plate with a cylinder with a tip diameter of 10 mm, and the maximum strength until the insulation plate breaks Was measured.

(Confirmation test for gas generation behavior difference)
In order to confirm the difference in gas generation behavior between the batteries of the electrode groups A and B, the batteries AD and BD are taken out one by one on behalf of the respective electrode groups, and the batteries at an ambient temperature of 25 ° C. and a constant current of 1500 mA. Then, constant current charging was performed until the end voltage of the battery reached 4.2 V, and then constant voltage charging was performed at a constant voltage of 4.2 V until the end current of the battery reached 100 mA. After storing this battery in the pressure vessel shown in FIG. 3, the pressure vessel was heated to 250 ° C. to forcibly generate gas, and the temperature and pressure changes in the pressure vessel were measured.

A specific measuring method will be described next. The battery AD or BD was installed at the position of the battery 6, and the battery 6 was installed in a chamber 7 equipped with a heater 8, a pressure gauge 9, and a thermometer 10. The battery 6 was heated by the heater 8, and the temperature was kept constant when the temperature in the chamber 7 reached 250 ° C. The gas generated in the battery 6 by exposing the battery 6 to 250 ° C. is released to the outside of the battery 6 (that is, in the chamber 7) through the exhaust valve of the battery 6. When the temperature in the chamber 7 reached 250 ° C., the pressure gauge 9 and the thermometer 10 were monitored, and the pressure and temperature changes in the chamber 7 were measured.

  An ideal gas equation of state PV = nRT (P is pressure, V is volume, n is the number of moles of gas molecules, R is a constant, and T is temperature), and is converted to a gas displacement at 20 ° C. FIG. 5 shows the integrated amount of the exhaust amount of the gas on the vertical axis and the elapsed time on the horizontal axis.

(Exhaust valve operation confirmation test when gas is generated)
Twenty batteries were withdrawn, and each battery was charged in the same manner as the confirmation test of the difference in behavior of gas generation. Then, after storing this battery in the pressure vessel shown in FIG. 3, the whole pressure vessel was heated to 250 ° C. to forcibly generate gas. After the gas was released to the outside of the case, the battery was taken out from the pressure vessel and the appearance was inspected. Gases released through the exhaust valve were recognized as “pass”.

表１の絶縁板の強度試験の結果から、絶縁板Ａ〜Ｅのように中心からの距離が半径の６０％以上の位置にガラス繊維があると強度が急激に減少していることがわかる。絶縁板Ｆ、Ｇ、Ｈの打ち抜き加工による切断端面を観察すると、ガラス繊維とフェノール樹脂の層間剥離が見られ、ガラス繊維が寸断されていることが確認できた。また、絶縁板Ｅでは、中心からの距離が半径の６０％以上の位置にガラス繊維がある部分では、層間剥離は見られず、ガラス繊維も寸断されず良好な状態であった。それにも関わらず、中心からの距離が半径の６０％以上の位置にガラス繊維がある部分では、ガラス繊維とフェノール樹脂の層間剥離が見られ、ガラス繊維が寸断されていることが確認できた。これは、打ち抜き加工される時に、ガラス繊維を積層した絶縁板の元となる材料が、材料押さえと下型に挟まれた状態で、上型から剪断応力を受けた時に引きちぎられるように変形し、積層部の層間を境にして剥れたことを示唆している。絶縁板Ｃについても同様の観察をしたところ、層間剥離は見られず、ガラス繊維も寸断されず良好な状態であった。これらの結果から、中心からの距離が半径の６０％より大きい位置にガラス繊維がある部分では、絶縁板の強度が低下すると考えられる。

From the result of the strength test of the insulating plate in Table 1, it can be seen that the strength decreases sharply when there is glass fiber at a position where the distance from the center is 60% or more of the radius as in the insulating plates A to E. When the cut end surfaces of the insulating plates F, G, and H by punching were observed, delamination between the glass fibers and the phenol resin was observed, and it was confirmed that the glass fibers were broken. In addition, in the insulating plate E, delamination was not observed in a portion where the glass fiber was located at a position where the distance from the center was 60% or more of the radius, and the glass fiber was not broken and was in a good state. Nevertheless, delamination between the glass fiber and the phenol resin was observed at the portion where the glass fiber was located at a position where the distance from the center was 60% or more of the radius, and it was confirmed that the glass fiber was broken. This is because when the punching process is performed, the original material of the insulating plate laminated with glass fibers is sandwiched between the material presser and the lower mold, and is deformed so as to be torn off when subjected to shear stress from the upper mold. This suggests that the film is peeled off between the layers of the laminated portion. When the same observation was made on the insulating plate C, no delamination was observed, and the glass fibers were in good condition without being cut. From these results, it is considered that the strength of the insulating plate is lowered at the portion where the glass fiber is located at a position where the distance from the center is larger than 60% of the radius.

In addition, from the results of the test for confirming the difference in gas generation behavior in Table 1, when the glass fiber is at a position where the distance from the center is 60% or more of the radius as in the batteries AF to AH and BF to BH, the exhaust valve is normally operated. It turns out that the pass rate which operates is extremely lowered. When the corresponding batteries AG and BG were disassembled and analyzed, it was confirmed that the insulating plate 2 was deformed to block the path between the electrode group and the exhaust valve. It is considered that this is because the insulating plate is deformed because the strength of the insulating plate is small with respect to the electrode group that moves toward the sealing plate as the gas is generated.

  Both the electrode groups A and B have an extremely low pass rate when using one insulating plate G that does not pass continuously from one end surface to the other end surface of the insulating plate. The probability of the battery BG was significantly low. This is considered to be due to the difference in gas generation behavior measured using the batteries AD and BD. That is, since the lithium nickel composite oxide generates a large amount of gas after pyrolysis, it is considered that the problems caused by using an insulating plate with reduced strength became prominent. From this result, it can be seen that when the non-aqueous electrolyte secondary battery is selected as the electrochemical element and the lithium nickel composite oxide is used as the positive electrode active material, the effects of the present invention are more remarkably exhibited.

  In addition, although the non-aqueous electrolyte secondary battery was demonstrated in the present Example, the same effect is acquired also in electrochemical elements other than a non-aqueous electrolyte secondary battery, such as an alkaline storage battery and a lead storage battery.

  In the present embodiment, the insulating plate in which three sheets are alternately laminated so that the direction of the glass fiber is 90 ° has been described. However, even if the direction of the glass fiber is 45 ° to 135 °, the number of laminated sheets other than three is 2 The same effect can be obtained with up to 5 sheets.

  In this embodiment, the case where the glass fiber is used alone as the skeleton material has been described. However, even if the skeleton material uses a metal fiber or a carbon fiber alone, a combination of glass fiber, metal fiber, and carbon fiber is used. The same effect can be obtained.

  The electrochemical device according to the present invention is useful as a power source for portable electric equipment that requires high capacity and high reliability, and is naturally used as a driving power source for automobiles and housing equipment such as elevators. It is also useful.

Schematic showing an example of the structure of the electrochemical element of this invention Schematic showing an example of the opening of the case before sealing with the sealing plate Schematic showing the measurement method to confirm the behavior of gas generation at high temperature Schematic diagram of a device for measuring the strength of an insulating plate Diagram showing differences in gas generation behavior at high temperatures due to differences in positive electrode active materials

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sealing plate 2 Insulating plate 3 Electrode group 4 Case 5a Hole part 5b Hole part 6 Battery 7 Chamber 8 Heater 9 Pressure gauge 10 Thermometer 11 Load meter 12 Apparatus

Claims (4)

The electrochemical element of the present invention is an electrochemical element in which an electrode group in which a positive electrode and a negative electrode are laminated via a separator is housed in a case having an opening, and the opening is sealed with a sealing plate,
The sealing plate has an exhaust valve having a function of releasing the pressure in the electrochemical element to the outside of the electrochemical element when the internal pressure of the electrochemical element reaches a predetermined pressure.
Having an insulating plate between the electrode group and the sealing plate;
The insulating plate is made of a thermosetting resin, includes glass fiber as a skeleton material, and has at least one hole.
The glass fiber is parallel to a line passing through the maximum outer diameter from one end surface to the other end surface of the insulating plate, and one continuous cut from the one end surface to the other end surface of the insulating plate is within 60% of the radius from the center. An electrochemical device having at least one location that passes through without any problem. The electrochemical element of the present invention is an electrochemical element in which an electrode group in which a positive electrode and a negative electrode are laminated via a separator is housed in a case having an opening, and the opening is sealed with a sealing plate,
The sealing plate has an exhaust valve having a function of releasing the pressure in the electrochemical element to the outside of the electrochemical element when the internal pressure of the electrochemical element reaches a predetermined pressure.
Having an insulating plate between the electrode group and the sealing plate;
The insulating plate is made of a thermosetting resin, includes a metal fiber as a skeleton material, and has at least one hole.
The metal fiber is parallel to a line passing through the maximum outer diameter from one end surface to the other end surface of the insulating plate, and one continuous cut from the one end surface to the other end surface of the insulating plate is within 60% of the radius from the center. An electrochemical device having at least one location that passes through without any problem. The electrochemical element of the present invention is an electrochemical element in which an electrode group in which a positive electrode and a negative electrode are laminated via a separator is housed in a case having an opening, and the opening is sealed with a sealing plate,
The sealing plate has an exhaust valve having a function of releasing the pressure in the electrochemical element to the outside of the electrochemical element when the internal pressure of the electrochemical element reaches a predetermined pressure.
Having an insulating plate between the electrode group and the sealing plate;
The insulating plate is made of a thermosetting resin, includes carbon fiber as a skeleton material, and has at least one hole.
The carbon fiber is parallel to a line passing through the maximum outer diameter from one end surface to the other end surface of the insulating plate, and one continuous cut from the one end surface to the other end surface of the insulating plate is within 60% of the radius from the center. An electrochemical device having at least one location that passes through without any problem. The electrochemical element of the present invention is an electrochemical element in which an electrode group in which a positive electrode and a negative electrode are laminated via a separator is housed in a case having an opening, and the opening is sealed with a sealing plate,
The sealing plate has an exhaust valve having a function of releasing the pressure in the electrochemical element to the outside of the electrochemical element when the internal pressure of the electrochemical element reaches a predetermined pressure.
Having an insulating plate between the electrode group and the sealing plate;
The insulating plate is made of a thermosetting resin, includes at least one of glass fiber, metal fiber, and carbon fiber as a skeleton material, and has at least one hole.
The fiber is parallel to a line passing through the maximum outer diameter from one end surface to the other end surface of the insulating plate, and one continuous cut from the one end surface to the other end surface of the insulating plate is within 60% of the radius from the center. An electrochemical element that has at least one passing point.

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