JP5558781B2 - Nonaqueous electrolyte secondary battery - Google Patents

Description

  The present invention relates to a non-aqueous electrolyte secondary battery, and more particularly to a cylindrical non-aqueous electrolyte secondary battery having a structure in which a cylindrical center pin is inserted into a hollow portion of a spirally wound electrode body. Next battery.

  It has high energy density as a drive power source for portable electronic devices such as today's mobile phones, portable personal computers and portable music players, and also as a power source for hybrid electric vehicles (HEV) and electric vehicles (EV). However, non-aqueous electrolyte secondary batteries represented by high-capacity lithium ion secondary batteries are widely used.

  Non-aqueous electrolyte secondary batteries are known to be rectangular and cylindrical. Among these, the cylindrical nonaqueous electrolyte secondary battery is a cylindrical wound electrode body in which a positive electrode plate and a negative electrode plate are wound via a separator. Is inserted into a cylindrical battery casing, a nonaqueous electrolyte is injected, and the opening of the battery casing is sealed in a sealed state by a sealing body on which a positive electrode or a negative electrode terminal is formed.

  By the way, when a secondary battery becomes overcharged, in which a current is supplied longer than usual at the time of charging, or when a large current flows due to misuse or failure of a device used, a positive electrode active material The negative electrode active material and the electrolytic solution react explosively, resulting in combustion while generating a large amount of gas. At this time, if a large amount of gas generated inside is not quickly discharged to the outside of the battery, the internal pressure of the battery suddenly increases, and in the worst case, the secondary battery suddenly explodes and is used. The device may be damaged. For this reason, in particular, in the case of a nonaqueous electrolyte secondary battery, a battery equipped with an explosion-proof safety valve has been used (see Patent Document 1 below).

  This safety valve must be reliably operated from the viewpoint of preventing damage to equipment and preventing fire accidents. Therefore, conventionally, as shown in Patent Document 1 below, a positive electrode plate and a negative electrode plate that are opposed to each other with a separator interposed between them are wound into a shape having a hollow portion at the center. A cylindrical center pin is disposed in the hollow portion of the wound electrode body, and a gas generated by overcharging or the like is disposed in the hollow portion of the wound electrode body. To the safety valve.

  In this center pin, the pressure generated by the gas generated inside the non-aqueous electrolyte secondary battery is applied in the overlapping direction of the positive electrode plate, negative electrode plate, and separator, so that the hollow portion is not crushed and the gas passage is not blocked. It is provided to do. The center pin also has a function of suppressing deformation of the electrode plate during expansion / contraction of the wound electrode body due to repeated charging / discharging of the nonaqueous electrolyte secondary battery. That is, when the wound electrode body expands due to repeated charge and discharge, it cannot expand to the outside constrained by the battery outer can, so it expands intensively toward the hollow portion, but a center pin is provided. Thus, deformation of the electrode plate in the vicinity of the hollow portion during expansion of the wound electrode body can be suppressed.

JP 2001-229905 A

As one of means for increasing the capacity of the battery, there is a method of increasing the number of turns of the wound electrode body by reducing the diameter of the core of the wound electrode body. Since the space at the center of the body is reduced, the diameter of the center pin is also reduced accordingly. On the other hand, there is a difference between the gas generation amount (a) (cm ³ / sec) from the bottom of the can and the center pin gas discharge capacity (b) (cm ³ / sec) when abnormal battery combustion occurs. It is empirically known that there is a relationship as shown in FIG. In this case, if there is a region A in which the gas generation amount (a) of the battery temporarily exceeds the gas discharge capacity (b) of the center pin, the pressure inside the battery is likely to increase, which may cause the battery to burst. come.

  Such a phenomenon is a problem if a melted material such as a resin member such as a separator having a low melting point or aluminum that is the core of the positive electrode body moves by combustion gas and passes through the center pin opening to the outside. Absent. However, if it touches a part whose temperature is low at that time during movement, it will be rapidly cooled and fixed. The center pin is lifted by the pressure of the combustion gas when there is a fixed substance inside, and the tip is in contact with the sealing body part. In such a state, there is no escape space for the melt that has passed through the center pin, and it adheres at the bottom and clogs the center pin, preventing gas from being discharged to the safety valve side, leading to rupture.

  Therefore, in the non-aqueous electrolyte secondary battery 50 disclosed in Patent Document 1, as shown in FIG. 5, a safety valve 52 is arranged at the top in the battery outer can 51, and the center hole 53 and the outer peripheral hole are formed at the bottom. 54, a perforated plate 55 is disposed, and a wound electrode body 57 is disposed on the perforated plate 55 via an insulating plate 56, and a center pin 58 is disposed in the center hole 53 of the perforated plate 55. Of the non-aqueous electrolyte secondary battery 50 by connecting one end of the non-aqueous electrolyte secondary battery 50 by forming a protrusion 59 at the bottom of the perforated plate 55 and securing a space between the perforated plate 55 and the bottom of the battery outer can 51. It is made difficult for the melt generated in this to move into the center pin 58, and the generated gas to easily move into the center pin 58.

  In the non-aqueous electrolyte secondary battery 50 disclosed in Patent Document 1 above, the gas generated during overcharge or the like can favorably move through the center pin 58 to the safety valve 52 side. There is an excellent effect that the electrolyte secondary battery 50 is prevented from bursting. However, in this non-aqueous electrolyte secondary battery 50, the insulating plate 56 and the perforated plate 55 are disposed between the wound electrode body 57 and the bottom of the battery outer can 51, and the perforated plate 55 and the battery Since a large space is formed between the bottom of the outer can 51 and the battery capacity is reduced, a problem arises.

  The present invention has been made to solve the above-mentioned problems, and gas generated during overcharge or the like while suppressing generation of a useless space that does not lead to an increase in battery capacity in the battery outer can. An object of the present invention is to provide a non-aqueous electrolyte secondary battery that can be circulated well in the center pin and that can safely suppress a breakdown accident by operating the safety mechanism normally.

In order to solve the above problems, the nonaqueous electrolyte secondary battery of the present invention is
A wound electrode body formed by winding a positive electrode plate and a negative electrode plate opposed to each other with a separator in a shape having a hollow portion at the center, a hollow center pin inserted into the hollow portion, and the winding In a non-aqueous electrolyte secondary battery comprising a battery outer can that houses an electrode body, and an external terminal that also serves as a safety valve that discharges gas when the gas pressure in the battery outer can exceeds a specified value .
Before Symbol center pin, the gap portion is formed from the spirally wound electrode body around a portion protruding to the bottom side of the battery outer can,
The internal volume of the center pin is Xcm ³ ,
The volume of the space at the bottom of the battery outer can centered on the center pin is Ycm ³ ,
The total volume in the battery outer can is Zcm ³ ,
And when
Y ≧ −0.14X + 0.16
X ≦ 0.015Z
It satisfies the following conditions.

  In the nonaqueous electrolyte secondary battery of the present invention, a gap is formed around the center pin located on the bottom side of the battery outer can. With such a configuration, for example, even when the amount of gas generated in the nonaqueous electrolyte secondary battery momentarily exceeds the gas discharge capacity of the center pin due to overcharging or the like, the excess gas remains in the gap at the bottom of the can. Therefore, rupture of the nonaqueous electrolyte secondary battery can be avoided.

  In this case, when the internal volume of the center pin is sufficiently larger than the total space volume in the battery (X> 0.015Z), the battery outer can can not be torn or ruptured, but a wasteful gap is not generated. It is not preferable because it is large and the battery capacity decreases. When the internal volume of the center pin is smaller than the total space volume in the battery (X ≦ 0.015Z), if the condition of Y ≧ −0.14X + 0.16 is satisfied, the battery outer can can tear or rupture However, when Y <−0.14X + 0.16, the battery outer can can be torn or ruptured.

  In the nonaqueous electrolyte secondary battery of the present invention, the wound electrode body is applicable not only to a cylindrical shape but also to an elliptical cylindrical shape.

  In the nonaqueous electrolyte secondary battery of the present invention, a can bottom insulating plate having a hole formed in the center is disposed between the bottom of the battery outer can and the wound electrode body, and the center pin It is preferable that one end portion is disposed so as to be located in an opening formed in the can bottom insulating plate.

  The non-aqueous electrolyte secondary battery has a can bottom insulating plate disposed between the bottom of the battery outer can and the wound electrode body for electrical insulation between the wound electrode body and the bottom of the battery outer can. Yes. In the non-aqueous electrolyte secondary battery of the present invention, a can bottom insulating plate having a hole formed in the center is used, and one end of the center pin is positioned in the hole formed in the can bottom insulating plate. By arranging, a gap is formed around the center pin located on the bottom side of the battery outer can. Therefore, according to the non-aqueous electrolyte secondary battery of the present invention, the capacity of the battery is not reduced by forming the gap around the center pin located on the bottom side of the battery outer can.

  In the nonaqueous electrolyte secondary battery of the present invention, it is preferable that a slit is formed on the peripheral surface of the center pin from one end to the other end in the length direction of the center pin.

  If a slit is formed on the peripheral surface of the center pin from one end to the other in the length direction of the center pin, the nonaqueous electrolyte secondary battery is overheated due to overcharging or the like, and a resin member such as a separator having a low melting point or a positive Even if the inner bottom surface side of the battery outer can of the center pin is blocked by a melt such as aluminum which is the core of the electrode plate, the inside of the center pin and the wound electrode body are connected through the slit formed in the center pin. A gas flow path is secured between them. Therefore, according to the nonaqueous electrolyte secondary battery of the present invention, even if gas is generated inside the battery due to overcharge or the like, it is possible to obtain a nonaqueous electrolyte secondary battery that is less likely to tear or rupture the battery outer can. .

It is a perspective view which cut | disconnects the cylindrical nonaqueous electrolyte secondary battery common to an Example and a comparative example in the vertical direction. It is an expanded sectional view of the center pin portion on the can bottom side. It is a graph which shows the presence or absence of the can tearing of a battery, etc. represented by the relationship between the internal volume X of a center pin, and the can bottom space | gap volume Y. It is a graph which shows the relationship between the gas generation amount in a battery, and the gas discharge capability of a center pin. It is a longitudinal cross-sectional view of the nonaqueous electrolyte secondary battery of a prior art example.

  Hereinafter, embodiments of the present invention will be described in detail with reference to Examples, Comparative Examples, and the drawings. However, the following examples illustrate lithium ion secondary batteries as non-aqueous electrolyte secondary batteries for embodying the technical idea of the present invention, and the present invention is specified in this example. And is equally applicable to other embodiments within the scope of the claims.

[Manufacture of non-aqueous electrolyte secondary batteries]
As shown in FIGS. 1 and 2, the nonaqueous electrolyte secondary battery 10 common to the examples and the comparative examples is a winding in which a positive electrode plate 11 and a negative electrode plate 12 are wound in a spiral shape via a separator 13. A rotating electrode body 14 is used, and a hollow portion 14 a is formed at the center of the wound electrode body 14. Insulating plates 15 and 16 are arranged on the upper and lower sides of the wound electrode body 14, respectively, and are housed inside a cylindrical battery outer can 17 having a bottom that also serves as a negative electrode terminal. As the battery outer can 17, for example, an iron one whose surface is nickel-plated is used.

The insulating plate 15 on the opening end side of the battery outer can 17 has a constant thickness, and the center portion is cut out to have the same diameter as the opening of the hollow portion 14a. Insulating plate 16 of the can bottom, depending on the respective Examples and Comparative Examples, the diameter of the thickness and the central portion of the aperture 16a (see FIG. 2) are changed, respectively. Details of the diameter of the aperture 16a of the thickness and the central portion of the can bottom side of the insulating plate 16 will be described later.

The negative electrode current collector tab 12a of the negative electrode plate 12 is welded to the inner bottom of the battery outer can 17, positive electrode current collector tabs 11a of the positive electrode plate 11, through aperture 15a formed in the insulating plate 15 (see FIG. 2) It is welded to the bottom plate portion of the positive electrode terminal 19 that also serves as the current interrupting sealing body 18. The current interrupting sealing body 18 has a function of disconnecting the electrical connection between the wound electrode body 14 and the outside of the battery due to an increase in the internal pressure of the battery. Even if the pressure is released once the connection is established It has a structure that does not return.

  A non-aqueous electrolyte (not shown) is injected into the battery outer can 17. Further, for example, a thin tubular stainless steel center pin 20 is disposed at the center of the wound electrode body 14, and the center pin 20 has one end in the longitudinal direction of the center pin 20 on the peripheral surface thereof. A slit 20a is formed from one end to the other end. The center pin 20 can be easily manufactured by bending an elongated metal plate into a cylindrical shape, but the slit 20 a is formed in parallel to the center axis of the center pin 20. In order to prevent the end of the slit 20 a from coming into contact with the spirally wound electrode body 14, the end of the slit 20 a is preferably formed so as to be located inward from the virtual outer periphery of the center pin 20. The opening of the battery outer can 17 is sealed by a positive electrode terminal 19 that also serves as a current interrupting sealing body 18 attached via a gasket 21.

  Here, the specific manufacturing method of the nonaqueous electrolyte secondary battery 10 common to an Example and a comparative example is demonstrated.

[Production of positive electrode plate]
An example of a method for producing the positive electrode plate 11 is as follows. First, lithium carbonate and a coprecipitated hydroxide represented by Ni _0.33 Co _0.34 Mn _0.33 (OH) ₂ are mixed, fired at 1000 ° C. for 20 hours in an air atmosphere, and then crushed. Thus, lithium nickel cobalt manganate (positive electrode active material A: LiNi _0.33 Co _0.34 Mn _0.33 O ₂ ) was obtained. Further, cobalt (Co) hydroxide, zirconium (Zr) hydroxide, aluminum (Al) hydroxide, and magnesium (Mg) hydroxide are co-precipitated and thermally decomposed to produce zirconium. Aluminum, magnesium-containing tricobalt tetroxide was obtained. This tricobalt tetroxide and lithium carbonate are mixed, calcined at 850 ° C. for 24 hours in an air atmosphere, and then crushed to obtain a zirconium, aluminum, magnesium-containing lithium cobalt composite oxide (positive electrode active material B). It was. Then, the positive electrode active material A and the positive electrode active material B were mixed at a mass ratio of 1: 9, and 99.5 parts by mass of the mixture and 0.5 parts by mass of lithium phosphate having an average particle diameter of 5 μm were mixed.

  94 parts by mass of the mixture, 3 parts by mass of acetylene black as a conductive agent, 3 parts by mass of polyvinylidene fluoride (PVdF) as a binder, and N-methyl-2-pyrrolidone (NMP) A positive electrode active material slurry was obtained. This positive electrode active material slurry was applied to both surfaces of an aluminum positive electrode current collector (thickness: 15 μm) using a doctor blade method and dried to remove the solvent (NMP) necessary for the slurry preparation. Thereafter, the dried electrode plate was rolled to have a thickness of 140 μm. Then, the positive electrode current collection tab 11a was attached to the core exposure part, and the positive electrode was completed.

[Manufacture of negative electrode plate]
An example of a method for producing the negative electrode plate 12 is as follows. First, 96 parts by mass of graphite as a negative electrode active material, 2 parts by mass of carboxymethyl cellulose (CMC) as a thickener, 2 parts by mass of styrene butadiene rubber (SBR) as a binder, and water are mixed. A negative electrode active material slurry was obtained. This negative electrode active material slurry was applied to both sides of a copper negative electrode current collector (thickness 8 μm) and dried to remove water necessary for the slurry preparation. Then, it rolled so that it might become thickness 140 micrometers. Then, the negative electrode current collection tab 12a was attached to the core exposure part, and the negative electrode was completed.

  The potential of graphite is 0.1 V with respect to lithium. In addition, the active material filling amount of the positive electrode and the negative electrode is the charge capacity ratio per unit area at the potential of the positive electrode active material which is a design standard (in this example, 4.45 V on the basis of lithium and 4.35 V). (Negative electrode charge capacity / positive electrode charge capacity) was adjusted so that the negative electrode was equal to or higher than the positive electrode.

[Preparation of non-aqueous electrolyte]
Fluorinated ethylene carbonate (FEC) represented by the following chemical formula 1 as a nonaqueous solvent, dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) in a volume ratio of 20:40:40 (25 ° C., 1 atm) And LiPF ₆ as an electrolyte salt was dissolved to 1.1 M (mol / liter) to give a non-aqueous electrolyte.

[Battery assembly]
Specifically, the wound electrode body 14 wound in a spiral shape was produced by the following method. First, the positive electrode plate 11 and the negative electrode plate 12 are superposed in a state where they are insulated from each other with a polyethylene microporous film (thickness 18 μm) separator 13 interposed therebetween, and are wound around a core member (not shown). Here, in the overlapped state, the separators 13 are arranged on the lowermost layer and the uppermost layer. The separator 13 is longer and wider than the positive electrode plate 11 and the negative electrode plate 12. On the other hand, the negative electrode plate 12 is wider than the positive electrode plate 11. One end of a positive electrode current collecting tab 11a made of aluminum is welded to a winding start portion of the positive electrode plate 11. Similarly, one end of a negative electrode current collecting tab 12 a made of nickel is welded to the winding end portion of the negative electrode plate 12.

The positive electrode current collecting tab 11a and the negative electrode current collecting tab 12a are flexible flat plates, and the surfaces thereof are covered with an insulating coating except for welded portions at both ends. In addition, the outermost periphery of the wound electrode body 14 wound in a spiral shape is stopped with an insulating tape so that the wound state is maintained. Moreover, winding remove the core member, and insert the insulating plate 16 the bottom center aperture 16a is formed of the spirally wound electrode body 14 which is wound spirally in contact with the cylindrical battery outer can 17, The negative electrode current collecting tab 12 a is welded to the inner surface central portion of the battery outer can 17 through the hollow portion 14 a generated by removing the winding core member from the wound electrode body 14.

  Next, a stainless steel thin tubular center pin 20 having a constant length L = 6 cm and various diameters and thicknesses is inserted, and a predetermined amount of the non-aqueous electrolyte prepared as described above is applied to the battery outer can. 17, and further welded to the positive electrode terminal 19 that also serves as the current blocking sealing body 18 to which the positive electrode current collecting tab 11 a is welded, and the gasket 21 is brought into contact with the periphery of the positive electrode terminal 19, thereby opening the battery outer can 17. By fixing the battery outer can 17 and the positive electrode terminal 19 in a liquid-tight state by caulking the ends, non-aqueous electrolyte secondary batteries common to the examples and the comparative examples are obtained.

The thin tubular center pin 20 has a constant length L of 6 cm, a diameter d of 0.20 cm, 0.25 cm and 0.30 cm, and a thickness t of 0.02 cm and 0.03 cm. It was. The width of the slit 20a of the center pin 20 is sufficiently shorter than the thickness t of the material for forming the center pin 20, and the volume of the slit 20a portion can be substantially ignored. The thickness of the can bottom side of the insulating plate 16 (the height h of the aperture) is 0.023, 0.150Cm, and four 0.230cm and 0.253Cm, further can bottom side of the insulating plate 16 diameter was formed in the central portion of the aperture 16a and (the center hole diameter D) 0.525cm, and three kinds of 0.870cm and 1.170cm. The relationship between the diameter d, thickness t and volume of each center pin 20 employed in Examples 1 to 4 and Comparative Examples 1 to 5, the center hole diameter D of the gap formed in the insulating plate 16 on the can bottom side, high The relationship between the height h and the volume Y is summarized in Table 1. In addition, the external shape of the battery common to each Example and Comparative Example was a cylindrical shape having a diameter of 1.8 cm and a height of 6.5 cm, and the total space volume Z in the battery was made constant at 14.5 cm ³ . . Moreover, the design capacity of the battery common to each Example and a comparative example is 2700 mAh.

[Heating test]
Regarding the batteries common to each of the examples and comparative examples manufactured as described above, 10 batteries are charged at a constant current of 1 It = 2700 mA until the battery voltage reaches 4.40 V, and the battery voltage is 4.40 V. Then, the battery was charged at a constant voltage of 4.40 V until the charging current reached 1/50 It = 54 mA, and the battery was fully charged. For these fully-charged batteries, whether the tip of the flame of the gas burner is in contact with the center of the bottom of the battery outer can 17 at an angle of 45 °, can the can tear or burst? We examined whether or not. As a result, a battery in which the contents of the battery did not pop out without causing abnormalities such as can tearing and rupturing was judged as a good product. The results obtained for each example and comparative example are summarized in Table 1. In addition, the numerical value in the column of the determination result in Table 1 indicates (number of cans torn battery / number of batteries used for test).

  Moreover, when the result shown in Table 1 is represented in a graph in which the horizontal axis is the internal volume X of the center pin and the vertical axis is the can bottom gap volume Y, the result is as shown in FIG. In addition, in FIG. 3, the thing which can tears is shown by "X" mark, and the thing where can tear did not arise is shown by "(circle)", Moreover, the position corresponding to Examples 1-4 is each shown. The positions indicated by E1 to E4 and corresponding to Comparative Examples 1 to 5 are indicated by R1 to R5, respectively.

From the results shown in FIG. 3, the following can be understood. That is, the internal volume X = 0.218 cm ^{3 of} the center pin becomes a critical point, and in the range of X> 0.218 cm ³ (Comparative Example 4 (R4)), there is no can tear or the like, but in X = 0.218 cm ³ There are those in which can tearing occurs (Comparative Examples 1 to 3 (R1 to R3)) and those that do not occur (Examples 1 and 2 (E1, E2). The range of X> 0.218 cm ³ in FIG. Also, in the range of X <0.218 cm ³ , if it is above the straight line represented by Y = −0.14X + 0.16 (range of Y> −0.14X + 0.16), Can tear does not occur, but if it is on the lower side (in the range of Y <−0.14X + 0.16), can tear has occurred.In FIG. 3, in the range of X <0.218 cm ³ , > -0.14X + 0.16 range is OKzon As has been shown, the scope of Y <-0.14X + 0.16 is shown as NGzone.

In the range of X> 0.218 cm ³ (Comparative Example 4 (R4)), the reason why can tearing does not occur is that the internal volume X of the center pin is large, so that the gas generated inside the battery is stored inside the center pin. This is thought to be possible. However, when the internal volume X of the center pin is increased in this way, the occupied capacity of the wound electrode body in the battery outer can decreases accordingly, so that the battery capacity is lowered. Here, X> 0.218 cm The range of ³ was a comparative example. In addition, in the range where the internal volume of the center pin is small, the volume Y of the can bottom gap required to prevent the battery outer can from bursting as the total space volume Z of the nonaqueous electrolyte secondary battery increases. Conceivable. In order to generalize, the internal volume X = 0.218cm ³ of the center pin represented using the entire space volume Z = 14.5cm ³ of the battery,
X = 0.218
= 0.218 (Z / 14.5)
= 0.015Z
It becomes.

That is, if the internal volume X of the center pin is in the range of X> 0.015Z, there is no inconvenience such as tearing of the battery outer can, but this range is not preferable because the battery capacity decreases. Further, in the range where the internal volume X of the center pin is small, that is, in the range of X ≦ 0.015Z, if the range of Y ≧ −0.14X + 0.16, tearing of the battery outer can does not occur, but Y < It can be seen that if the range is −0.14X + 0.16, the battery outer can can be torn. This means that even if the internal volume X of the center pin is reduced, can tearing of the battery outer can can be suppressed by increasing the volume Y of the can bottom gap. In addition, when the internal volume X of the center pin is reduced, the occupied volume of the wound electrode body in the battery outer can can be increased by that amount, so that the battery capacity can be increased. Note that the can bottom pore volume Y is because it is intended to be formed by the open hole formed in the insulating plate of the center pin and the can bottom side, it does not affect the battery capacity by increasing the can bottom void volume Y.

  In Examples 1 to 4 described above, the negative electrode plate 12 is also provided with the negative electrode current collecting tab 12a, and the negative electrode current collecting tab 12a is welded to the inner bottom portion of the battery outer can 17; The electric tab 12a may be welded to any portion of the battery outer can 17 as long as the electrical connection between the battery outer can 17 and the battery outer can 17 can be ensured, or the outermost electrode contacts the battery outer can 17 directly. It may be formed. Further, in the first to fourth embodiments of the present invention, the case of the spirally wound electrode body 14 wound in a spiral shape with the positive electrode plate 11 on the inner peripheral side and the negative electrode plate 12 on the outer peripheral side has been described. Even if the arrangement of the plate 11 and the negative electrode plate 12 is reversed, the same effect can be obtained.

DESCRIPTION OF SYMBOLS 10 ... Nonaqueous electrolyte secondary battery 11 ... Positive electrode plate 11a ... Positive electrode current collection tab 12 ... Negative electrode plate 12a ... Negative electrode current collection tab 13 ... Separator 14 ... Winding electrode body 14a ... Hollow part 15 ... Insulation plate 15a ... (Insulation plate) of) aperture 16 ... insulating plate 16a ... (insulating plates) aperture 17 ... battery outer can 18 ... current interrupting sealing body 19 ... positive electrode terminal 20 ... center pin 20a ... slit 21 ... gasket D ... central hole diameter d ... diameter X ... Internal volume (of center pin) Y ... Can bottom gap volume Z ... Total space volume

Claims (3)

A wound electrode body formed by winding a positive electrode plate and a negative electrode plate opposed to each other with a separator in a shape having a hollow portion at the center, a hollow center pin inserted into the hollow portion, and the winding In a non-aqueous electrolyte secondary battery comprising a battery outer can that houses an electrode body, and an external terminal that also serves as a safety valve that discharges gas when the gas pressure in the battery outer can exceeds a specified value .
Before Symbol center pin, the gap portion is formed from the spirally wound electrode body around a portion protruding to the bottom side of the battery outer can,
The internal volume of the center pin is Xcm ³ ,
The volume of the space at the bottom of the battery outer can centered on the center pin is Ycm ³ ,
The total volume in the battery outer can is Zcm ³ ,
And when
Y ≧ −0.14X + 0.16
X ≦ 0.015Z
A non-aqueous electrolyte secondary battery characterized by satisfying the following conditions.   A can bottom insulating plate having an opening formed in the center is disposed between the bottom of the battery outer can and the wound electrode body, and the center pin is an open end having one end formed on the can bottom insulating plate. The nonaqueous electrolyte secondary battery according to claim 1, wherein the nonaqueous electrolyte secondary battery is disposed so as to be located in the hole.   3. The nonaqueous electrolyte secondary battery according to claim 1, wherein a slit is formed on a peripheral surface of the center pin from one end to the other end in the length direction of the center pin. 4.

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