JP2015041416A - Power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power storage device capable of suppressing actuation failure of a pressure actuation member due to reduction in strength of a case body.SOLUTION: A case of a secondary battery is structured of a bottomed cylindrical case body and a lid body closing an opening of the case body, and an electrode assembly and an electrolyte are housed therein. The secondary battery includes a pressure release valve actuated by internal pressure of the case. The case body contains 4.5-5.5 mass% Si, 2.5-3.5 mass% Cu, 1.2-1.5 mass% Mg, less than 0.3 mass% Ni (here, including 0 mass%), less than 0.5 mass% Fe (here, including 0 mass%), and the balance Al with unavoidable impurities. The case body is prepared so that the porosity amount becomes equal to or less than 5 vol.% using an aluminum alloy A in which the ratio [Mg/Cu] of Mg content to Cu content is 0.4-0.7.

Description

  The present invention relates to a power storage device.

  A vehicle such as an EV (Electric Vehicle) or a PHV (Plug in Hybrid Vehicle) is equipped with a secondary battery such as a lithium ion battery as a power storage device that stores power supplied to an electric motor serving as a prime mover. The secondary battery includes an electrode assembly in which a positive electrode obtained by applying a positive electrode active material to a metal foil and a negative electrode obtained by applying a negative electrode active material to a metal foil are insulated with a separator and laminated in layers. The case of the secondary battery includes a bottomed cylindrical case body and a lid that closes the opening of the case body, and accommodates an electrode assembly and an electrolytic solution.

  In addition, a pressure operating member that operates according to the internal pressure of the case, such as a pressure release valve (gas discharge valve) and a current interrupt device (CID), is disposed in the case of the secondary battery. For example, in the secondary battery described in Patent Document 1, a pressure relief valve is provided on the lid of the case.

JP 2011-181214 A

  Aluminum has the property that the strength decreases as the temperature increases. For this reason, for example, when an aluminum case body is used for the case of the secondary battery, the strength of the case body decreases as the temperature of the case increases. Normally, the internal pressure of the case increases with the temperature rise of the case, but when the strength of the case main body decreases with the temperature rise of the case, the case main body expands with the temperature increase of the case. The internal pressure will decrease. And although a case is high temperature, there exists a possibility that the internal pressure of a case may not reach the working pressure of the preset pressure action member, and a pressure action member may not act | operate.

  The present invention has been made paying attention to such problems existing in the prior art, and an object of the present invention is to provide a power storage capable of suppressing the malfunction of the pressure operating member due to the strength reduction of the case body. To provide an apparatus.

  A power storage device for solving the above-described problem includes a bottomed cylindrical case main body and a lid that closes an opening of the case main body, and a case in which an electrode assembly and an electrolytic solution are accommodated. And a pressure actuating member that is actuated by the internal pressure of the case. And the case body is Si: 4.5-5.5 mass%, Cu: 2.5-3.5 mass%, Mg: 1.2-1.5 mass%, Ni: less than 0.3 mass% (However, including 0% by mass) Fe: Less than 0.5% by mass (however, including 0% by mass), the balance being Al and inevitable impurities, and the ratio of Mg content to Cu content [Mg / Cu] is produced using an aluminum alloy having a content of 0.4 to 0.7 so that the nest amount is 5 vol% or less.

  When copper (Cu) and magnesium (Mg) are dissolved in the aluminum matrix, the mechanical strength of the aluminum alloy is improved by solid solution strengthening. In addition, when copper and magnesium coexist in the aluminum alloy, the S phase (Cu2MgAl) is precipitated by producing a cast product or a forged product so that the amount of nest is 5 vol% or less. This improves the mechanical strength of the aluminum alloy. However, when there is too little content of copper and magnesium, the effect mentioned above cannot be acquired. Moreover, the upper limit of content of copper and magnesium is the solid solubility limit in the aluminum alloy mentioned above.

  When silicon (Si) is contained together with copper and magnesium in the aluminum alloy, the S phase (Cu2MgAl) and β phase ( Mg2Si) precipitates, and the mechanical strength required in the high temperature region can be obtained by the precipitation strengthening action of both. However, if the content of silicon, copper and magnesium is too small, the above-described effects cannot be obtained.

  Further, when the copper and magnesium contents are equal to or higher than the lower limit, the castability is remarkably lowered. However, when the silicon content is equal to or higher than the lower limit, the deterioration of the castability can be suppressed. On the other hand, when there is too much content of silicon, the coarse intermetallic compound containing aluminum and copper will produce | generate, and high temperature strength will fall on the contrary.

  Various inevitable impurities are contained in the aluminum alloy. When nickel (Ni) and iron (Fe) are contained in the aluminum alloy, castings and forgings so that the nest amount is 5 vol% or less. By forming an intermetallic compound with aluminum, the high temperature strength is improved. However, when the content of nickel and iron is not less than the above upper limit value, a coarse intermetallic compound is formed, and the high-temperature strength is lowered. The content of nickel and iron may be 0% by mass.

The reason why the nest amount is 5 vol% or less is that if the nest amount is too large, the high temperature strength is greatly affected and the high temperature strength is lowered.
According to the above configuration, by employing the case body of the case made of an aluminum alloy having the above component ratio, the strength of the case body can be ensured even when the temperature of the case increases. For this reason, the case main body is less likely to swell with the temperature rise of the case, and the internal pressure of the case is less likely to decrease. Therefore, it is possible to suppress the malfunction of the pressure actuating member due to the strength reduction of the case body.

  When a pressure release valve that is provided on the lid body and opens when the internal pressure of the case exceeds a predetermined operating pressure is adopted as the pressure operating member, the pressure release valve and the lid body are Si: 4.5. -5.5 mass%, Cu: 2.5-3.5 mass%, Mg: 1.2-1.5 mass%, Ni: less than 0.3 mass% (however, including 0 mass%), Fe : Less than 0.5% by mass (however, including 0% by mass), comprising the balance Al and inevitable impurities, and the ratio of Mg content to Cu content [Mg / Cu] is 0.4 to 0.7 It is desirable that the nest amount be 5 vol% or less using an aluminum alloy.

  If an aluminum lid is used for the case and an aluminum pressure relief valve is provided on the lid, the strength of the lid and the pressure relief valve decreases due to the temperature rise of the case. The operating pressure of the release valve may fluctuate.

  According to the above configuration, by adopting a lid body and a pressure relief valve made of an aluminum alloy having the above component ratio, the strength of the lid body and the pressure relief valve is ensured even if the temperature of the case rises. Can do. Therefore, the fluctuation | variation of the operating pressure of the pressure release valve resulting from the strength fall of a cover body and a pressure release valve can be suppressed.

As the pressure actuating member, it is possible to adopt a current interrupting device that interrupts the current when the internal pressure of the case exceeds a predetermined operating pressure.
Even when a current interrupting device (CID) is employed as the pressure actuating member, if the case body expands as the case temperature rises and the internal pressure of the case decreases, the current interrupting device may malfunction.

  According to the said structure, since the intensity | strength of a case main body can be ensured even if the temperature of a case rises, the malfunctioning of the electric current interruption apparatus resulting from the strength reduction of a case main body can be suppressed.

  An example of the power storage device is a secondary battery.

  According to the present invention, it is possible to suppress the malfunction of the pressure actuating member due to the temperature change of the case.

The perspective view which shows the external appearance of a secondary battery. The table | surface which shows the composition of an aluminum alloy. The graph which shows the relationship between temperature and tensile strength about the aluminum alloy of an Example, and the aluminum alloy of a comparative example. The table | surface which shows the tensile strength in the temperature of 230 degreeC about the aluminum alloy of an Example and the aluminum alloy of a comparative example.

Hereinafter, an embodiment embodying a power storage device will be described with reference to FIGS.
As shown in FIG. 1, in a secondary battery 10 as a power storage device, an electrode assembly 12 is accommodated in a case 11. The case 11 also contains an electrolyte solution together with the electrode assembly 12. The case 11 includes a bottomed cylindrical case main body 13 and a flat lid 14 that closes an opening 13 a into which the electrode assembly 12 is inserted into the case main body 13. In the case 11, the opening 13a of the case main body 13 and the outer peripheral portion of the lid body 14 are joined by, for example, laser welding. Both the case body 13 and the lid body 14 are made of an aluminum alloy. In addition, the secondary battery 10 of this embodiment is a rectangular battery whose appearance is a rectangular shape because the case body 13 is a bottomed rectangular tube shape and the lid body 14 is a rectangular flat plate shape. Moreover, the secondary battery 10 of this embodiment is a lithium ion battery.

  The electrode assembly 12 includes a positive electrode, a negative electrode, and a separator that insulates the positive electrode and the negative electrode. The positive electrode is configured by applying a positive electrode active material to both surfaces of a positive metal foil (aluminum foil). The negative electrode is configured by applying a negative electrode active material to both surfaces of a negative electrode metal foil (copper foil). The electrode assembly 12 has a laminated structure in which a plurality of positive electrodes and a plurality of negative electrodes are alternately laminated, and a separator is interposed between the two electrodes. In addition, the positive electrode terminal 15 and the negative electrode terminal 16 are electrically connected to the electrode assembly 12. Each part of the positive electrode terminal 15 and the negative electrode terminal 16 is exposed to the outside of the case 11 from the lid body 14. Further, a ring-shaped insulating ring 17 a for insulating from the case 11 is attached to the positive terminal 15 and the negative terminal 16, respectively.

  In addition, the case 11 is cleaved when the pressure in the case 11 reaches an operating pressure that is a predetermined pressure so that the pressure in the case 11 does not increase too much. A pressure release valve 20 is provided as a pressure actuating member to be opened. In this embodiment, the pressure release valve 20 is located on the lid 14. Further, the operating pressure of the pressure release valve 20 is set to a pressure at which the case 11 itself or the joint portion between the case main body 13 and the lid body 14 can be broken before cracks or breakage can occur.

  The pressure release valve 20 has a thin plate-like valve body 21 that is thinner than the plate thickness of the lid body 14. Further, the pressure release valve 20 has a track-shaped periphery in which two parallel straight portions are connected by an arc portion. The valve body 21 of the pressure release valve 20 is connected to the periphery of the pressure release valve 20 and has a track shape like the pressure release valve 20. Further, the valve body 21 is located at the bottom of the concave portion 22 provided in the lid body 14 and is formed integrally with the lid body 14. And the valve body 21 has the cleavage groove | channel 23 containing two linear grooves which cross | intersect X shape, for example.

  In the present embodiment, the case body 13 of the case 11 is manufactured using an aluminum alloy having a predetermined composition by casting such as gravity casting. The case body 13 of the case 11 is manufactured so that the nest amount is 5 vol% or less.

  Next, comparison results between an aluminum alloy as an example used in the case main body 13 of the present embodiment and an aluminum alloy as a comparative example having a composition different from the aluminum alloy of the example are shown in FIGS. This will be described with reference to FIG.

  FIG. 2 shows aluminum alloys A to F having different compositions. In addition, the aluminum alloy A is an aluminum alloy as an example used as a material of the case body 13 of the case 11 in the present embodiment. Aluminum alloys B to F are aluminum alloys as comparative examples.

  As shown in FIG. 2, the aluminum alloy A as an example is 4.96% by mass of silicon (Si), 3.02% by mass of copper (Cu), 1.48% by mass of magnesium (Mg), nickel It contains 0.29% by mass of (Ni) and 0.47% by mass of iron (Fe). And it consists of remainder Al and an unavoidable impurity, and ratio [Mg / Cu] of Mg content to Cu content is 0.4-0.7. Inevitable impurities include, for example, manganese (Mn), zinc (Zn), titanium (Ti), and chromium (Cr). The aluminum alloy A as an example contains 0.01% by mass of manganese, 0.01% by mass of zinc, and 0.02% by mass of titanium as inevitable impurities. That is, the aluminum alloy A as an example has Si: 4.5 to 5.5 mass%, Cu: 2.5 to 3.5 mass%, Mg: 1.2 to 1.5 mass%, Ni: 0 It is an aluminum alloy containing less than 3 mass% (however, including 0 mass%), Fe: less than 0.5 mass% (however, including 0 mass%). Moreover, it is an aluminum alloy which consists of remainder Al and an unavoidable impurity and whose ratio [Mg / Cu] of Mg content with respect to Cu content is 0.4-0.7. On the other hand, in aluminum alloys B to F as comparative examples, the proportion of some of the components contained is outside the above range.

  While producing a cast product using each of the aluminum alloys A to F, a tensile test piece is cut out from the center of each produced cast product, and a tensile test is performed under a temperature of 25 ° C. to 230 ° C. to obtain a tensile strength. It was measured. FIGS. 3 and 4 show the tensile strength of a cast product produced using an aluminum alloy A (hereinafter referred to as “the cast product of the example”) and a cast product produced using aluminum alloys B to F (hereinafter referred to as “cast products of the examples”). It is a figure which shows the data of the experiment which this inventor performed about the tensile strength of "the casting of a comparative example". In addition, after performing the solution treatment which heats each said casting at 530 degreeC for 10 hours, it quenches with the boiling water, and also performs the aging treatment which heats at 170 degreeC for 10 hours. FIG. 3 shows one tendency as the casting of the comparative example, but the aluminum alloys B to F have the same tendency as this tendency although the numerical values of the tensile strength are different from each other.

  As described above, when the case main body 13 swells when the case 11 is at a high temperature, the internal pressure of the case 11 may decrease and may not reach the operating pressure of the pressure release valve 20. Further, when the case 11 is near 200 ° C., the performance of the secondary battery 10 may be greatly deteriorated. Therefore, it is desirable to open the pressure release valve 20 around 200 ° C. That is, the tensile strength of aluminum rapidly decreases at 200 ° C. The absolute temperature is half the melting point of aluminum (about 660 ° C.), which is 200 ° C. (≈ (660 ° C. + 273 ° C.) / 2−273 ° C.). This is because the diffusion of the metal becomes faster and the alloy metal structure starts to collapse. In order to suppress the malfunction of the pressure release valve 20 at the high temperature of the case 11 and avoid the performance degradation of the secondary battery 10, the temperature is 230 ° C., which is the temperature obtained by adding 30 ° C. to 200 ° C. Experiments revealed that it is desirable to use an aluminum alloy that can secure a tensile strength of 170 MPa as the material of the case body 13 of the case 11.

As shown in FIG. 3, the tensile strength of both the cast product of the example and the cast product of the comparative example decreases with increasing temperature.
As shown in FIG. 4, the tensile strength under the condition where the temperature is 230 ° C. is 175 MPa for the aluminum alloy A as an example, whereas the aluminum alloys B to F as comparative examples are less than 170 MPa.

Based on FIGS. 2-4, the relationship between the composition of aluminum alloys B-F as a comparative example and tensile strength is considered below.
Aluminum alloy B contains 1.20 mass% copper and 0.52 mass% magnesium. That is, in the aluminum alloy B, the copper content is less than the range of Cu: 2.5 to 3.5% by mass, and the magnesium content is less than the range of Mg: 1.2 to 1.5% by mass. It is running low.

  Here, as described above, when copper and magnesium are dissolved in the aluminum matrix, the mechanical strength of the aluminum alloy is improved by solid solution strengthening. In addition, when copper and magnesium coexist in the aluminum alloy, the S phase (Cu2MgAl) is precipitated by producing a cast product or a forged product so that the amount of nest is 5 vol% or less. This improves the mechanical strength of the aluminum alloy. However, when there is too little content of copper and magnesium, the effect mentioned above cannot be acquired. Moreover, the upper limit of content of copper and magnesium is the solid solubility limit in the aluminum alloy mentioned above. In aluminum alloy B, since the contents of copper and magnesium are too small, the effect of improving the mechanical strength by copper and magnesium cannot be obtained, and it is estimated that the tensile strength at a temperature of 230 ° C. was 130 MPa. The

  The aluminum alloy C contains 1.80% by mass of copper and 0.51% by mass of magnesium, respectively. Like the aluminum alloy B, the contents of copper and magnesium are less than the above range. Further, the aluminum alloy C contains 8.90% by mass of silicon. That is, in the aluminum alloy C, the silicon content is larger than the range of Si: 4.5 to 5.5% by mass.

  Here, as described above, if the silicon content is too large, a coarse intermetallic compound containing aluminum and copper is generated, and the high temperature strength is lowered. In aluminum alloy C, since the contents of copper and magnesium are too small, the effect of improving the mechanical strength due to copper and magnesium cannot be obtained, and the content of silicon is too large, so the high temperature strength is lowered. For these reasons, it is presumed that the aluminum alloy C had a tensile strength of 125 MPa under a temperature of 230 ° C.

  Aluminum alloy D contains 0.25% by mass of chromium. Here, as described above, when nickel and iron are included as unavoidable impurities in the aluminum alloy, by producing a cast or forged product so that the amount of nest is 5 vol% or less, it is possible to form a Forms compounds and improves high temperature strength. Since aluminum alloy D contains chromium of the same transition metal instead of nickel, the above-described effect due to the inclusion of nickel is not recognized, and an intermetallic compound is crystallized. For these reasons, it is presumed that the aluminum alloy D had a tensile strength of 100 MPa at a temperature of 230 ° C.

  Aluminum alloy E contains 2.50 mass% copper and 0.48 mass% magnesium. That is, in the aluminum alloy E, the copper content is higher than that of the aluminum alloys B to D, and is within the above range. On the other hand, the content of magnesium is less than the above range, similar to the aluminum alloys B to D. In the aluminum alloy E, although the effect of improving the mechanical strength by copper is obtained, since the content of magnesium is too small, the effect of improving the mechanical strength by magnesium cannot be obtained, and the temperature is 230 ° C. It is estimated that the tensile strength of 148 MPa was 148 MPa.

  Aluminum alloy F contains 3.02 mass% copper and 1.22 mass% magnesium. That is, in the aluminum alloy F, the contents of copper and magnesium are larger than those of the aluminum alloys B to E, and are within the above range. Furthermore, the aluminum alloy F contains 0.19 mass% of silicon. That is, in the aluminum alloy F, the silicon content is less than the above range.

  Here, as described above, when silicon is contained together with copper and magnesium in the aluminum alloy, the S phase (Cu2MgAl) is produced by producing a cast product or a forged product so that the nest amount is 5 vol% or less. And β phase (Mg 2 Si) precipitate, and the mechanical strength required in the high temperature region can be obtained by the precipitation strengthening action of both. However, if the content of silicon, copper and magnesium is too small, the above-described effects cannot be obtained.

  Moreover, the aluminum alloy F contains 0.89 mass% of nickel and 1.80 mass% of iron, respectively. That is, in the aluminum alloy F, the nickel content is larger than the range of Ni: less than 0.3 mass% (including 0 mass%), Fe: less than 0.5 mass% (provided that 0 mass%). The iron content is higher than the range of

  Here, as described above, when nickel and iron are included as unavoidable impurities in the aluminum alloy, by producing a cast or forged product so that the amount of nest is 5 vol% or less, it is possible to form a Forms compounds and improves high temperature strength. However, when the content of nickel and iron is not less than the above upper limit value, a coarse intermetallic compound is formed, and the high-temperature strength is lowered.

  In aluminum alloy F, since the content of silicon is too small, the effect of improving the mechanical strength by silicon, copper and magnesium cannot be obtained, and since the content of nickel and iron is too large, the high temperature strength is reduced. Yes. For these reasons, it is presumed that the aluminum alloy F had a tensile strength of 150 MPa at a temperature of 230 ° C.

Next, the operation of this embodiment will be described.
By adopting the case body 13 of the case 11 made of the aluminum alloy A described above, the strength of the case body 13 can be ensured even when the temperature of the case 11 rises. For this reason, the case body 13 is less likely to swell as the temperature of the case 11 rises, and the internal pressure of the case 11 is less likely to decrease. That is, since the internal pressure of the case 11 reaches the preset operating pressure of the pressure release valve 20 when the case 11 is at a high temperature, the pressure release valve 20 can be operated.

Therefore, according to the present embodiment, the following effects can be obtained.
(1) By adopting the case main body 13 of the case 11 made of an aluminum alloy having the above component ratio, the strength of the case main body 13 can be ensured even when the temperature of the case 11 rises. Therefore, the malfunction of the pressure release valve 20 due to the strength reduction of the case body 13 can be suppressed.

  (2) If a wrought material is used as the material of the case body 13, the fluidity of the molten metal is low, and casting cannot be used as a method for producing the case body 13. For this reason, when the case main body 13 has a complicated shape, it is difficult to manufacture the case main body 13. According to the present embodiment, since the aluminum alloy containing silicon is adopted as the material of the case body 13, the fluidity of the molten metal can be ensured, and casting can be adopted as a method for producing the case body 13. For this reason, even if the case body 13 has a complicated shape, the case body 13 can be easily manufactured.

The above-described embodiment can be modified as follows.
(Circle) the aluminum alloy used for the case main body 13 of the case 11 is not restricted to what has the composition of the aluminum alloy A mentioned above. That is, Si: 4.5 to 5.5 mass%, Cu: 2.5 to 3.5 mass%, Mg: 1.2 to 1.5 mass%, Ni: less than 0.3 mass% (however, 0 It may be an aluminum alloy containing Fe: less than 0.5 mass% (including 0 mass%). Moreover, what is necessary is just the aluminum alloy which consists of remainder Al and an unavoidable impurity, and the ratio [Mg / Cu] of Mg content with respect to Cu content is 0.4-0.7. As long as each component is within such a range, the composition of the aluminum alloy used for the case body 13 is not limited.

  The lid 14 and the pressure release valve 20 of the case 11 may be made of an aluminum alloy having a composition within the above range so that the nest amount is 5 vol% or less. According to such a form, in addition to the effects that can be obtained in the above embodiment, the following effects can be obtained.

  If the lid 14 made of aluminum is used for the case 11 and the pressure release valve 20 made of aluminum is also provided in the lid 14, the strength of the lid 14 and the pressure release valve 20 is increased by the temperature rise of the case 11. By decreasing, the operating pressure of the pressure release valve 20 may fluctuate. According to this modification, the lid 14 and the pressure release valve 20 are used even when the temperature of the case 11 rises by adopting the lid 14 and the pressure release valve 20 made of an aluminum alloy having the above component ratio. The strength of the can be ensured. Therefore, the fluctuation | variation of the operating pressure of the pressure release valve 20 resulting from the strength fall of the cover body 14 and the pressure release valve 20 can be suppressed.

The shape of the pressure release valve 20 may be a shape other than the track shape such as a circular shape.
O The shape of the cleavage groove 23 of the pressure release valve 20 may be changed.
O Formation of the cleavage groove 23 in the valve body 21 of the pressure release valve 20 may be omitted.

  The lid 14 and the pressure release valve 20 may be separate parts, and the pressure release valve 20 may be joined to the lid 14 of the case 11. The joining is performed by, for example, laser welding. In this case, the metal used for manufacturing the pressure release valve 20 may be an aluminum alloy having the same composition as that of the lid 14 or may be an aluminum alloy having a different composition.

  The pressure release valve 20 may be made of a metal other than an aluminum alloy. In addition, the pressure release valve 20 may be made of a metal other than an aluminum alloy, and a metal layer may be provided on the surface of the pressure release valve 20 to suppress fluctuations in the strength of the pressure release valve 20 due to a temperature change of the case 11.

  The lid 14 may be made of a metal other than an aluminum alloy. The lid body 14 may be made of a metal other than an aluminum alloy, and a metal layer may be provided on the surface thereof to suppress fluctuations in the strength of the lid body 14 due to temperature changes of the case 11.

  The pressure release valve 20 may be provided on the case body 13 of the case 11. In this case, the pressure release valve 20 may be an aluminum alloy having the same composition as the case body 13 or may be an aluminum alloy having a different composition. Further, it may be made of a metal other than an aluminum alloy.

  The secondary battery 10 may include a current interrupt device (CID) that interrupts current when the pressure in the case 11 exceeds a predetermined operating pressure, instead of the pressure release valve 20. Moreover, you may make it provide both the pressure release valve 20 and an electric current interruption apparatus. According to such an embodiment, the following effects can be obtained in addition to the effects that can be obtained in the above-described embodiment and the above-described modified examples.

  Even when a current interrupting device (CID) is employed as the pressure operating member, if the case body 13 swells and the internal pressure of the case 11 decreases as the temperature of the case 11 rises, the current interrupting device may malfunction. According to this embodiment, since the strength of the case main body 13 can be ensured even when the temperature of the case 11 rises, the malfunction of the current interrupting device due to the strength reduction of the case main body 13 can be suppressed.

○ The case body 13 may be produced by forging.
○ The shape of the case 11 may be changed. For example, the case 11 may be cylindrical.
The electrode assembly 12 is not limited to the laminated type, and may be a wound type in which a belt-like positive electrode and a belt-like negative electrode are wound and laminated in layers.

  The secondary battery 10 is a lithium ion secondary battery, but is not limited thereto, and may be another secondary battery. In short, any ion may be used as long as ions move between the positive electrode active material layer and the negative electrode active material layer and transfer charge. Further, a capacitor may be used as the power storage device.

  (Circle) the secondary battery 10 may be mounted in a motor vehicle as a vehicle power supply device, and may be mounted in an industrial vehicle. Further, the present invention may be applied to a stationary power storage device.

  DESCRIPTION OF SYMBOLS 10 ... Secondary battery, 11 ... Case, 12 ... Electrode assembly, 13 ... Case main body, 13a ... Opening part, 14 ... Cover body, 20 ... Pressure release valve, 23 ... Cleavage groove.

Claims (4)

A case body having a bottomed cylindrical case and a lid that closes the opening of the case body, and a case in which the electrode assembly and the electrolytic solution are accommodated,
A power storage device including a pressure operating member that operates according to an internal pressure of the case,
The case body is composed of Si: 4.5 to 5.5% by mass, Cu: 2.5 to 3.5% by mass, Mg: 1.2 to 1.5% by mass, Ni: less than 0.3% by mass ( However, Fe: less than 0.5% by mass (provided that 0% by mass is included), the balance is made of Al and inevitable impurities, and the ratio of Mg content to Cu content [Mg / A power storage device manufactured using an aluminum alloy having a Cu] of 0.4 to 0.7 so that the nest amount is 5 vol% or less. The pressure operating member includes a pressure release valve that is opened when an internal pressure of the case exceeds a predetermined operating pressure,
The pressure relief valve is provided on the lid;
The pressure release valve and the lid body are composed of Si: 4.5 to 5.5% by mass, Cu: 2.5 to 3.5% by mass, Mg: 1.2 to 1.5% by mass, Ni: 0.00. Fe containing less than 3% by mass (however, including 0% by mass), Fe: less than 0.5% by mass (however, including 0% by mass), the balance being Al and inevitable impurities, and Mg content relative to Cu content The power storage device according to claim 1, wherein the nest amount is 5 vol% or less using an aluminum alloy having a ratio [Mg / Cu] of 0.4 to 0.7.   The power storage device according to claim 1, wherein the pressure operating member includes a current interrupt device that interrupts current when an internal pressure of the case exceeds a predetermined operating pressure.   The power storage device according to any one of claims 1 to 3, wherein the power storage device is a secondary battery.