JP2009245650A - Sealed battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealed battery capable of securing its safety even if a cylindrical sealed battery in an erected state is crushed from above. <P>SOLUTION: The sealed battery 10 is housed in a conductive cylindrical battery package can 6 where an upper part of a spiral electrode body 5 wound by a positive electrode plate 2 and a negative electrode plate 3 via a separator 4 is opened. A negative electrode collection tab 3a arranged on the negative electrode plate 3 is electrically connected with the battery package can 6, and a positive electrode collection tab 2a arranged on the positive electrode plate 2 is electrically connected with a terminal plate 12 arranged on an opening sealing body 10, and the opening sealing body 10 is airtightly fixed on the battery package can 6 by caulking the vicinity of an opening 6c of the battery package can 6. The positive electrode collection tab 2a is connected with the terminal plate 12 by coating it with an electrically-insulated positive electrode tab protection tape having heat-resisting temperature of 270°C or above, tensile strength of 120 N or above, and piercing strength of 9.8 N or above. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a sealed battery, and more particularly to a sealed battery that can ensure safety even when a cylindrical sealed battery is crushed from above while standing.

  Various types of batteries are used as power sources for various electronic devices such as mobile terminals typified by mobile phones. Among these batteries, many secondary batteries that can be repeatedly charged are used. Such batteries include lithium ion batteries, alkaline storage batteries, nickel-cadmium batteries and nickel-hydrogen batteries. These batteries are also referred to as sealed batteries because the electrode bodies are housed together with the electrolyte in a battery outer can. Among these batteries, non-aqueous electrolyte secondary batteries represented by lithium ion batteries have excellent characteristics, such as high operating voltage (3 V or higher), high theoretical energy density compared to aqueous battery, and self-discharge. Therefore, its application has been expanded because it has characteristics such as a low operating temperature range, a wide operating temperature range, and excellent liquid leakage resistance.

  Here, an outline of a general nonaqueous electrolyte secondary battery will be described with reference to FIG. FIG. 4 is a cross-sectional view of a conventional nonaqueous electrolyte secondary battery. The non-aqueous electrolyte secondary battery 20 can accommodate a spiral electrode body 24 in which a positive electrode plate 21 and a negative electrode plate 22 are wound via a separator 23, the spiral electrode body 24, and a predetermined amount of electrolyte. It has a bottomed cylindrical battery outer can 25 having a size and an upper opening, and a sealing body 28 for closing the upper opening of the battery outer can 25. The battery is assembled as follows. First, after the insulating plate 26, the spiral electrode body 24, and the insulating plate 27 are accommodated in this order in the battery outer can 25, for example, a negative electrode current collecting tab provided on the negative electrode plate 22 is welded to the inner bottom portion of the battery outer can 25. Then, the positive electrode current collecting tab 21 a provided on the positive electrode plate 21 is welded to the terminal plate 30. Next, after a predetermined amount of non-aqueous electrolyte is injected from the opening 25 a of the battery outer can 25, the sealing body 28 is inserted into the opening 25 a of the battery outer can 25, and the gasket 32 is interposed between the battery outer can 25 and the battery outer can 25. It is assembled by caulking and sealing the opening 25a side end.

  However, the non-aqueous electrolyte secondary battery 20 having such a configuration can be chemically coupled between the positive electrode plate, the negative electrode plate, and the non-aqueous electrolyte housed in the battery outer can when some energy is applied from outside or inside. A reaction may occur and the internal pressure may rise abnormally, causing the battery to rupture or ignite. For example, when an overcharged state occurs or an internal short circuit occurs for some reason and a large current flows, the electrolytic solution may be decomposed to generate gas. As a result, the internal pressure of the battery rises abnormally and ruptures or ignites, and the equipment in which the battery is stored may be damaged, burned out, or spread to the surroundings, causing a serious accident. In addition, when the battery ruptures, the electrolytic solution or corrosive gas may be scattered to corrode external equipment or the like.

Therefore, this type of non-aqueous electrolyte secondary battery is provided with a safety device for avoiding rupture or ignition (for example, see Patent Documents 1 to 3 below). For example, in the battery described in Patent Document 1 below, the positive electrode lead is bent, but when the positive electrode lead bend comes into contact with the beading portion of the battery outer can, an internal short-circuited state occurs. Is covered with an insulating tape so that a short circuit does not occur even if the positive electrode lead is bent. Moreover, the battery described in the following Patent Document 2 is one in which a safety device is incorporated in a laminated sealing body, and the battery described in the following Patent Document 3 is one in which a safety device is incorporated in a caulking type sealing body. It is.
Japanese Patent Laid-Open No. 10-302751 (paragraph [0033], FIG. 1) JP-A-5-251076 (paragraphs [0015] to [0022], FIG. 1) Japanese Patent Laid-Open No. 10-241644 (paragraphs [0017] to [0019], FIG. 1)

  Since the batteries disclosed in Patent Documents 1 to 3 are provided with a safety device against energy applied from the outside or the inside, their safety is ensured. That is, these batteries have been subjected to various tests in the design or manufacturing process, and their safety has been verified. For example, the battery disclosed in Patent Document 3 performs a drop test in which the battery is turned upside down, that is, the sealing body is dropped downward from a height of 1.5 m above the floor onto a concrete floor. Thus, it has been confirmed that the amount of deformation of the flange portion is within the range of the safety value and that no leakage occurs. Further, in the inventions disclosed in other patent documents, it is verified that no rupture or ignition occurs by performing an overcharge test and a nail penetration test. These battery tests include electrical tests such as overcharge, mechanical tests such as drop tests, and environmental tests such as temperature and humidity. Mechanical tests include a crash test, an impact test, a vibration test, and a crush test. For example, the collision test is a test that is performed by dropping a weight having a predetermined weight from above, and the crushing test is a test that is performed by applying a predetermined crushing force to two flat plates. These tests are usually performed in two directions of the battery cell.

  Since nonaqueous electrolyte secondary batteries have excellent characteristics, their applications have been further expanded in recent years, and their usage forms have been varied with the expansion of these applications. For this reason, the safety test cannot be sufficiently performed only by the conventional test methods, and a test method capable of verifying higher safety is required. For example, when a crushing test is performed on a cylindrical battery, it is usually performed by applying a predetermined crushing force from above in a state where the cylindrical battery is laid on the floor surface. However, even if this same crushing test is performed with the nonaqueous electrolyte secondary battery standing on the floor, the battery has high capacity and high output characteristics. Explosions and fires could lead to dangerous conditions. Therefore, the crushing test performed in a state where such a nonaqueous electrolyte secondary battery is erected, that is, a so-called vertical crushing test is extremely difficult to carry out because it involves danger. In addition, in each said patent document, nothing is mentioned about such a longitudinal crush test.

Therefore, the present inventors investigated the cause of the rupture and ignition of the nonaqueous electrolyte secondary battery in this longitudinal crush test. As a result, in the process of crushing the standing nonaqueous electrolyte secondary battery from above, the electrical short circuit generally occurs between the positive electrode and the negative electrode (X _{2 in} FIG. 4) due to deformation of the caulking lower portion of the outer can. Battery outer can deformation-short circuit between electrodes (hereinafter referred to as "can body deformation-short circuit between electrodes") and between the positive electrode plate (mainly positive current collecting tab) and the negative electrode plate located below the positive terminal (see Fig. 4 X ₁ ) was found to occur at two locations of the short-circuit between electrodes (hereinafter referred to as “short-circuit between electrodes”). Furthermore, when the relationship between these short-circuited locations and rupture and ignition was sought, the timing of short-circuit occurring at two locations X ₁ and X _{2 in} the crushing process, that is, “can-deformed-electrode short-circuit” and “electrode It was found that the degree of rupture and ignition differed greatly depending on the timing of “short circuit”. That is, if a short circuit occurs first at X ₂ out of X ₁ and X ₂ locations, and a short circuit does not occur immediately after X ₁ locations, a dangerous state will not occur. However, on the contrary, or occurs a short circuit in the X ₁ place earlier, a short circuit even X ₁ in a short time a short-circuit on the X ₂ points occurs is generated, it will induce severe rupture and fire. The reason for this is that the short circuit at X ₂ is mainly a short circuit between the positive electrode active material and the negative electrode active material, and is a reaction that is not so severe, but the short circuit at X ₁ is the metal part of the positive electrode and the negative electrode active material. Vigorous reaction occurs because of the reaction involving. Therefore, leading to an explosion or fire the battery when the short-circuit by X ₁ point occurs are stored a lot of energy. However, when a short circuit occurs at X ₁ location after a short circuit does not occur at X ₁ location, or a short circuit occurs at X ₂ location and a short circuit occurs at X ₁ location, the energy is no longer enough to cause a violent reaction. It is considered that it does not lead to rupture or fire.

Therefore, the present inventors, in the longitudinal crush test, first caused a short circuit at X ₂ out of the two locations X ₁ and X ₂ , and much energy was consumed when the short circuit started at X _1. by the like being, on the basis of the finding that the risk of explosion and fire is eliminated and extensive studies of conditions that structure initially as a short circuit X ₂ places results are obtained. As a result, the positive electrode current collecting tab is covered with an electrically insulating protective tape having predetermined characteristics, and the vertical length of the assembled battery, that is, the total length of the battery, the width of the negative electrode plate and this if the distance between the bottom of the negative electrode plate end portion and the sealing member in a predetermined ratio, eliminating the occurrence of a short circuit in the X ₁ point, or found to be delayed occurrence of a short circuit in the X ₁ point, the present invention It has come to be completed.

  That is, the object of the present invention is to further improve the safety of the cylindrical sealed battery, and the safety is ensured even under severe conditions such as crushing from above in a state where the cylindrical sealed battery is erected. An object of the present invention is to provide a sealed battery.

The sealed battery of the present invention includes a spiral electrode body wound in a state where a positive electrode plate and a negative electrode plate are insulated from each other via a separator, and a bottomed cylindrical battery exterior housing the spiral electrode body Cans,
Sealed in an electrically insulated state at the opening of the battery outer can, and having a terminal cap, a safety valve mechanism and a terminal plate,
With
In a sealed battery in which a current collecting tab formed on one of the positive electrode plate and the negative electrode plate is electrically connected to the terminal plate,
The current collecting tab is covered with an electrically insulating protective tape having a heat resistant temperature of 270 ° C. or higher, a tensile strength of 120 N or higher, and a puncture strength of 9.8 N or higher.

If the current collecting tab connected to the terminal plate is covered with an electrically insulating protective tape having a heat resistance of 270 ° C. or higher, a tensile strength of 120 N or higher, and a piercing strength of 9.8 N or higher, Even when crushed from above, this protective tape ensures insulation until a short circuit occurs between the battery outer can and the electrode. Therefore, according to the sealed battery of the present invention, when the battery is crushed from above, eliminating the occurrence of a short circuit in the X ₁ point, or it is possible to delay the occurrence of a short circuit in the X ₁ point, severe Since a short circuit between the metal part of the positive electrode causing the reaction and the negative electrode active material is suppressed, there is no risk of rupture and ignition, and safety is further improved.

  In the present invention, “above the battery” means the upward direction when the cylindrical battery is erected. In addition, as the “electrically insulating protective tape having a heat resistant temperature of 270 ° C. or higher, a tensile strength of 120 N or higher, and a puncture strength of 9.8 N or higher” in the present invention, a tape made of polyimide can be used.

  In the sealed battery of the present invention, it is preferable that the current collecting tab is covered with the protective tape at least a portion corresponding to the width of the negative electrode plate of the current collecting tab in the battery outer can.

  If the current collecting tab is covered with a protective tape at least a portion corresponding to the width of the negative electrode plate of the current collecting tab in the battery outer can, even if the battery is crushed from above the battery, Since the insulating property is secured by the protective tape, the insulating property can be maintained until a short circuit occurs between the battery outer can and the electrode. Therefore, according to the sealed battery of the present invention, a sealed battery with improved safety can be obtained. The current collecting tab is more preferably covered with a protective tape at a portion longer than the portion corresponding to the width of the negative electrode plate, and the portion longer than the portion corresponding to the width of the separator is further covered. preferable. However, it is not preferable to cover the protective tape up to the portion where the current collecting tab is welded to the outer can or the terminal plate, because this hinders welding.

  In the sealed battery of the present invention, the width in the direction perpendicular to the winding direction of the negative electrode plate is 89% or more with respect to the length of the sealed battery, and the upper part of the negative electrode plate to the lower part of the sealing body Is preferably set to 3.7% or more with respect to the length of the sealed battery.

  The width in the direction perpendicular to the winding direction of the negative electrode plate is 89% or more of the length of the sealed battery, and the distance from the upper part of the negative electrode plate to the lower part of the sealing body is the length of the sealed battery. On the other hand, when the battery is set to 3.7% or more, when the battery is crushed from above, the current collector tab is physically short-circuited between the electrode connected to the terminal plate and the other electrode. In addition, the deformation of the battery outer can easily causes a short circuit between the positive and negative electrodes. For this reason, the above-described effects of the present invention are produced without variation.

  Further, in the sealed battery according to the present invention, the safety valve mechanism is deformed by an increase in pressure in the battery outer can and interrupts an electrical connection between the terminal plate and the terminal cap. It is preferable that the terminal cap and the terminal plate have a gas vent path or have an opening.

  According to the sealed battery of the present invention, since the energizing circuit shut-off mechanism and the gas vent path for shutting off the energizing circuit due to an abnormal increase in internal pressure are provided in the sealing body, it is possible to suppress an excessive increase in the internal pressure in the battery outer can, Rupture or ignition can be prevented in advance. Further, by making the metal terminal cap thicker than, for example, twice the thickness of the caulking type sealing body, a predetermined mechanical strength can be maintained even when the metal terminal cap is crushed in a standing state.

  In the sealed battery of the present invention, the sealing body includes the terminal cap, the safety valve mechanism, and the terminal plate stacked, and these parts are caulked using the open end portion of the outer can through the gasket. A laminated sealing body is preferred.

  As a sealing body of a sealed battery, a terminal cap and a safety valve mechanism are caulked and sealed using a terminal plate, and the caulked sealing body is caulked at the opening end of an outer can and a laminated state Both of the stacked types assembled in are well known. However, even if the means for releasing the gas is clogged with the melt of the electrode body in the state in which the pressure in the battery outer can is increased, the laminated type sealing body is not subject to further increase in pressure. Since a gas venting path is secured in a gap generated due to heat, deformation, or the like between the parts, an excessive increase in internal pressure in the battery outer can can be suppressed. Therefore, according to the sealed battery of the present invention using the laminated sealing body, the above effect is remarkably exhibited.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to FIGS. However, the embodiment shown below illustrates and explains a nonaqueous electrolyte secondary battery as a sealed battery for embodying the technical idea of the present invention, and the present invention is not limited to this nonaqueous electrolyte secondary battery. The invention is not intended to be specified as a battery, and can be equally applied to other sealed batteries without departing from the technical idea shown in the claims.

  FIG. 1 is a longitudinal sectional view of a nonaqueous electrolyte secondary battery according to an embodiment of the present invention. FIG. 2 is a plan view showing a current collecting tab attachment portion of the positive electrode plate together with the negative electrode plate and the separator. FIG. 3 is a longitudinal sectional view of the sealing body of FIG. FIG. 4 is a cross-sectional view of a conventional cylindrical nonaqueous electrolyte secondary battery.

  First, a non-aqueous electrolyte secondary battery according to an embodiment of the present invention will be described with reference to FIG. The non-aqueous electrolyte secondary battery 1 includes a spiral electrode body 5 in which a positive electrode plate 2 and a negative electrode plate 3 are wound via two separators 4, and the spiral electrode body 5 and a predetermined amount of electrolyte. The bottomed cylindrical battery outer can 6 is large enough to accommodate the battery and the upper opening 6c of the battery outer can 6 is closed. Among these components, the negative electrode plate 3 has a configuration in which a negative electrode active material layer is formed on a negative electrode current collector having a predetermined width in a direction orthogonal to the longitudinal direction.

  Further, the positive electrode current collecting tab 2a is welded to the positive electrode plate 2, and the negative electrode current collecting tab 3a (see FIG. 1) is welded to the negative electrode plate 3, respectively. Among them, the positive electrode current collecting tab 2a is covered with a protective tape (hereinafter referred to as “positive electrode tab protective tape”) 7 having predetermined characteristics, as shown in FIG. When the assembled battery assembly is erected, the positive electrode tab protective tape 7 is first deformed when the battery outer can 6 is deformed and before the positive and negative electrodes are short-circuited. Further, it is formed of an insulating material having a characteristic that can prevent a short circuit from occurring between the positive electrode current collecting tab 2a and the negative electrode plate 3. Specifically, the positive electrode tab protection tape 7 is an electrically insulating tape having a heat resistance of 270 ° C. or more, a tensile strength of 120 N or more, and a puncture strength of 9.8 N or more, and for example, a polyimide tape is used. The

The non-aqueous electrolyte secondary battery 1 has a length in the longitudinal direction in a state where the sealing body 10 is attached to the battery outer can 6 and assembled, that is, the entire height from the bottom to the top in the standing state. (Hereinafter referred to as “battery total height”) is H ₁ , the negative electrode plate width H ₄ and the gap H ₃ between the lower part of the sealing body 10 and the upper part of the negative electrode plate are a predetermined ratio with respect to the total battery height H ₁ It is configured as follows. That is, the battery total height _{H 1} as 100%, the negative electrode plate width _{H 4} 89% or more and the gap _{H 3} is set to more than 3.7%.

By adopting such a configuration, even when crushed from above in an upright state, the battery outer can 6 is first physically deformed to cause the positive electrode plate 2 and the negative electrode plate 3 (X _{2 in} FIG. 1). And a gas generated inside the battery outer can 6 is released to the outside from this location, and an abnormal increase in internal pressure is avoided. This prevents rupture and ignition. Then, even in the event a short circuit between the positive and negative electrodes at the point where the positive electrode tab is connected (X ₁ point in FIG. 1), since there is no the internal pressure rises abnormally, there is no possibility of explosion and fire, safer Will be improved.

  Next, with reference to FIG. 2, the sticking state of the positive electrode plate 2 and the positive electrode tab protection tape 7 to this positive electrode plate 2 is demonstrated. The positive electrode plate 2 includes a strip-like positive electrode current collector 2c having a predetermined length in the length direction and a predetermined width length in a direction orthogonal to this direction, and a positive electrode active material applied to at least one surface of the positive electrode current collector 2c. The positive electrode current collector 2c is formed with a plain portion 2d that is not partially coated with the positive electrode active material layer. A positive electrode current collecting tab 2a is welded to the plain portion 2d. The positive electrode current collecting tab 2 a is covered with a positive electrode tab protective tape 7. The positive electrode tab protection tape 7 is formed of an electrical insulating tape having a heat resistance of 270 ° C. or more, a tensile strength of 120 N or more, and a puncture strength of 9.8 N or more, for example, a polyimide tape.

The negative electrode plate 3 has a strip-shaped negative electrode current collector that is slightly longer in length and width than the positive electrode plate 2, and a negative electrode active material layer applied to at least one surface of the current collector. It is a plain part where this active material is not applied. A negative electrode current collecting tab 3a is welded to the plain portion. The width H ₄ of this negative electrode plate is 89% or more of the total height H ₁ (100%) of the assembled battery.

  The positive electrode plate 2 and the negative electrode plate 3 are each wound in a spiral shape with a separator 4 interposed therebetween to form a spiral electrode body 5.

The battery outer can 6 has a size capable of accommodating the spiral electrode body 5 and a predetermined amount of electrolyte, and is formed of a bottomed circular cylinder with an opening at the top, and is formed of, for example, a nickel-plated steel material. ing. The battery outer can 6 has a circular bottom 6b, a side wall 6a erected from the periphery of the bottom, and an upper opening 6c. Thickness _{d 1} of the bottom is, for example, 0.4 mm.

  Next, the structure of the sealing body 10 is demonstrated with reference to FIG. As shown in FIG. 3, the sealing body 10 includes an iron terminal cap 11 formed in an inverted dish shape (cap shape) and an aluminum terminal plate 12 formed in a dish shape. The terminal cap 11 includes a convex portion 11a that bulges toward the outside of the battery, and a flat plate-like flange portion 11b that constitutes the bottom side of the convex portion, and a plurality of gas vent holes are formed at the corners of the convex portion 11a. 11c is provided. The terminal cap 11 has a high mechanical strength by punching a relatively thick iron plate, applying nickel plating to the surface, and having a thickness twice that of the caulking type sealing body. . Further, the size of the side vent hole 11c is preferably at least three times as large as the area ratio of the vent hole of the caulking type sealing body.

  On the other hand, the terminal plate 12 includes a recess 12a that bulges toward the inside of the battery, and a flat flange portion 12b that constitutes the bottom side of the recess. Gas vent holes 12c are provided at the corners of the recess 12a. The terminal cap 11 and the terminal plate 12 accommodate, for example, an aluminum valve body 13 that functions as a safety valve that deforms when the gas pressure inside the battery rises and exceeds a predetermined pressure. ing.

  A support portion 12a ′ (thickness of 0.1 to 0.5 mm) having a thickness thinner than that of the periphery is formed in the central portion of the concave portion 12a of the terminal plate 12, and the support portion 12a ′ is thin (0.02). A notch 12d having a thickness of about 0.15 mm is formed. When the internal pressure of the battery rises, the notch 12d is preferentially broken from the notch 12d portion by the support portion 12a ′ of the recessed portion of the terminal plate 12 welded to the valve body 13 as the valve body 13 is deformed. The terminal cap 11 and the terminal plate 12 are provided to be disconnected from each other. This prevents the abnormal reaction from continuing and the battery internal pressure from becoming excessive.

  This valve body 13 consists of the recessed part 13a and the flange part 13b, for example, is comprised from the aluminum metal whose thickness is 0.3 mm-0.5 mm. An intermediate material (clad material) is interposed between the flange portion 13b of the valve body 13 and the flange portion 11b of the terminal cap 11, and the aluminum material and the iron material are welded. The lowest part of the recess 13a of the valve body 13 is disposed so as to contact the surface of the support 12a ′ of the recess 12a of the terminal plate 12, and is welded to the support 12a ′.

  The valve body 13 is formed with a notch 13c so as to be partially thin so as to surround the recess 13a. The notch 13c is provided to prevent the valve body 13 from being broken from the notch 13c when the internal pressure of the battery is greatly increased, so that the internal pressure of the battery does not become excessive.

  Further, the flange portion 13 b of the valve body 13 is sandwiched between the flange portion 11 b of the terminal cap 11 and the flange portion 12 b of the terminal plate 12 via an annular insulator 14. The insulator 14 is fixed, for example, by applying a paste on both sides.

  Further, the flange portion 11b of the terminal cap 11, the flange portion 13b of the valve body 13 and the flange portion 12b of the terminal plate 12 are, for example, open end portions of the battery outer can 6 via an insulating gasket 15 (see FIG. 1) made of polypropylene. The battery outer can 6 is liquid-tightly sealed in the opening 6c of the battery outer can 6 by caulking the vicinity of the upper end portion of the battery outer can 6 to the terminal cap 11 side. In addition, the thickness of a crimping part becomes a half of the conventional crimping type sealing body.

  With this structure, the non-aqueous electrolyte secondary battery 10 is configured such that when the gas pressure inside the battery rises and exceeds a predetermined pressure, the recess 13a of the valve body 13 is deformed, so that the recess 12a of the terminal plate 12 is removed from the notch 12d. By being broken, the electrical contact between the valve body 13 and the terminal plate 12 is interrupted and the current is interrupted. Thereby, this sealing body has a current interruption device (Current Interrupt Device) function.

  Next, the assembly of the nonaqueous electrolyte secondary battery 1 will be described with reference to FIGS. In order to assemble this non-aqueous electrolyte secondary battery, the insulating plate 8, the spiral electrode body 5 and the insulating plate 9 are inserted in this battery outer can 6 in this order, and the negative electrode current collecting tab 3 a is connected to the bottom of the battery outer can 6. Weld to 6b. Since the battery outer can 6 has the negative electrode current collecting tab 3a welded to the battery outer can 6, the battery outer can 6 also serves as a negative electrode terminal. Then, a recess 6d is formed in the vicinity of the opening by beading. Next, the positive electrode current collecting tab 2 a is welded to the terminal plate 12 provided on the sealing body 10. Then, after injecting a predetermined amount of nonaqueous electrolyte from the opening 6 c of the battery outer can 6, the sealing body 10 is fitted into the opening 6 c of the battery outer can 6, and an insulating gasket is provided between the sealing body 10 and the battery outer can 6. 15 is interposed, and the sealing body 10 is sealed in the opening 6 c of the battery outer can 6 by crimping the vicinity of the opening 6 c of the battery outer can 6.

In this assembly process, the gap H ₃ from the upper part of the negative electrode plate 3 to the terminal plate 12 below the sealing body 10 is adjusted to 3.7% or more with respect to the total battery height H ₁ (100%) of the assembly. That is, the battery of the assembly total height _{H 1,} the vertical height _{H 4} of the negative electrode plate 3, a gap as _{H 3,} the ratio of _{H 4} and _{H 3} to the battery total height _{H 1} is the _{H 1} as 100%, H ₄ is adjusted to 89% or more and H ₃ is adjusted to 3.7% or more. If the thickness of the bottom of the battery outer can 6 is d1, and the thickness of the insulating plate 8 at the bottom is d2, then H ₁ = H ₂ + H ₃ + H ₄ + d ₁ + d ₂ .

  Moreover, the sealing body 10 has a higher safety. That is, even if the location of the arrow A1 in FIG. 3 is blocked by the crushing, this pressure acts in the direction of the arrow A2 due to the increase in internal pressure, and the insulating plate 14 is moved to form a gas passage in this portion. Released from the arrow A3. Examples of the present invention will be described below.

  The non-aqueous electrolyte secondary battery of the example was manufactured using the following members. As the sealing body 10, the laminated sealing body 10 having the configuration shown in FIG. 3 was used. The sealing body 10 has a configuration in which a terminal cap 11 is made of an iron material, and an insulator 14 is disposed between a terminal plate 12 and a valve body (rupture disk) 13. As the positive electrode tab protective tape 7, a polyimide tape having a thickness of 30 μm was used. Using these members, a 18650 series capacity nonaqueous electrolyte secondary battery (design capacity: 1200 mAh) having a cylindrical diameter of 18 mm and a length of 65 mm was produced. The dimensions of each part of Example 1 are summarized in Table 1.

  The nonaqueous electrolyte secondary battery of Comparative Example 1 is the same as that of the example except that a caulking type sealing body that has been widely used as a sealing body and a polypropylene tape (thickness 30 μm) is used for the positive electrode tab protection tape. A non-aqueous electrolyte secondary battery having the same configuration was obtained. Further, the nonaqueous electrolyte secondary battery of Comparative Example 2 is the same as that of the example except that a caulking type sealing body that has been widely used as a sealing body and a polypropylene tape (thickness 30 μm) is used as the positive electrode tab protection tape. A non-aqueous electrolyte secondary battery having the same configuration was obtained. Furthermore, the nonaqueous electrolyte secondary battery of Comparative Example 3 was a nonaqueous electrolyte secondary battery having the same configuration as that of the example except that a polypropylene tape (thickness 30 μm) was used for the positive electrode tab protection tape. The physical properties of the polyimide tapes used in Examples and Comparative Example 2 and the polypropylene tapes used in Comparative Examples 1 and 3 are shown in Table 1.

[Vertical crush test]
Ten nonaqueous electrolyte secondary batteries of Examples and Comparative Examples 1 to 3 assembled as described above were prepared, charged at a constant current of 1 It = 1200 mA until the battery voltage reached 4.2 V, and the battery After the voltage reached 4.2 V, the battery was charged at a constant voltage of 4.2 V until the current reached 1/50 It = 26 mA, and the battery was fully charged. Each battery thus fully charged is erected on a flat iron plate with the sealing body facing up, and the metal measuring head is pressed in the longitudinal direction from the sealing body side at a speed of 1 mm / sec. A vertical crush test was conducted to investigate the state of destruction of each battery. The results are summarized in Table 2.

  As is clear from the results shown in Table 2, it was demonstrated that the nonaqueous electrolyte secondary battery according to this example had improved safety. In the above Examples and Comparative Examples 1 to 3, the example in which the positive electrode plate is connected to the sealing body and the negative electrode plate is connected to the battery outer can has the same effect even if this arrangement is reversed. Played.

It is a longitudinal cross-sectional view of the nonaqueous electrolyte secondary battery which concerns on embodiment of this invention. It is a top view which shows the current collection tab attachment part of a positive electrode plate with a negative electrode plate and a separator. It is a longitudinal cross-sectional view of a sealing body. It is sectional drawing of the conventional cylindrical nonaqueous electrolyte secondary battery.

Explanation of symbols

1: nonaqueous electrolyte secondary battery (sealed battery) 2: positive electrode plate 2a: positive electrode current collector tab 2b: positive electrode active material 2c: positive electrode current collector 2d: plain part 3: negative electrode plate 4: separator 5: spiral electrode body 6: outer can 6a: opening 7: positive electrode tab protective tape 8,9: insulating plate 10: sealing member 11: positive terminal 12: terminal board 13: safety valve 14: insulator 15: gasket X _{1, X 2:} short circuit Point

Claims (5)

A spiral electrode body wound in a state where the positive electrode plate and the negative electrode plate are insulated from each other via a separator;
A bottomed cylindrical battery outer can containing the spiral electrode body;
Sealed in an electrically insulated state at the opening of the battery outer can, and having a terminal cap, a safety valve mechanism and a terminal plate,
With
In a sealed battery in which a current collecting tab formed on one of the positive electrode plate and the negative electrode plate is electrically connected to the terminal plate,
The sealed tab is covered with an electrically insulating protective tape having a heat resistant temperature of 270 ° C. or higher, a tensile strength of 120 N or higher, and a puncture strength of 9.8 N or higher.   2. The sealed battery according to claim 1, wherein the current collecting tab covers at least a portion corresponding to the width of the negative electrode plate of the current collecting tab in the battery outer can with the protective tape. .   The width in the direction perpendicular to the winding direction of the negative electrode plate is 89% or more of the length of the sealed battery, and the distance from the upper part of the negative electrode plate to the lower part of the sealing body is the length of the sealed battery. The sealed battery according to claim 1, wherein the battery is set to 3.7% or more.   The safety valve mechanism includes an energization circuit shut-off mechanism that is deformed by an increase in pressure in the battery outer can and shuts off an electrical connection between the terminal plate and the terminal cap, and the terminal cap and the terminal plate The sealed battery according to claim 1, wherein the battery is a gas venting path or has an opening.   The sealing body is a laminated sealing body in which the terminal cap, the safety valve mechanism, and the terminal plate are laminated and the terminal cap, the safety valve mechanism, and the terminal plate are caulked using the open end of the outer can via a gasket. The sealed battery according to claim 1, wherein the battery is a sealed battery.

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