JP5176807B2 - Power storage device, vehicle and storage container - Google Patents

Description

  The present invention relates to a power storage device in which a power storage body that generates heat by charging and discharging is stored in a storage container.

  2. Description of the Related Art A power storage body that can be charged and discharged is known as a power source body that supplies power to a traveling motor of a hybrid vehicle or an electric vehicle. This type of power storage unit is usually configured by connecting a plurality of power storage elements in series in order to obtain a high output.

  The power storage body generates heat due to charging / discharging, but deterioration is promoted when the temperature is raised to a predetermined temperature or higher. Therefore, it is necessary to cool the power storage unit so as not to exceed a predetermined temperature. As a method for cooling the power storage unit, a method is known in which a sealed case is filled with a coolant having high thermal conductivity, and the power storage unit is immersed in the coolant.

Patent Document 1 discloses a battery case including a metal case having a thickness of 0.1 mm or more and 2 mm or less, which has an appearance similar to that of a battery housed therein, and aluminum is exemplified as the material of the metal case. ing.
Japanese Patent Laid-Open No. 04-104458 (refer to claim 1, embodiment 2)

  However, the temperature of the power storage unit mounted on the vehicle changes depending on the environment outside the vehicle. That is, the temperature of the power storage unit decreases when the environment outside the vehicle is extremely low, and the temperature of the power storage unit increases when the environment outside the vehicle is high. Further, the temperature of the power storage unit rises with the charging operation and the discharging operation.

  The coolant existing around the power storage unit expands when the temperature of the power storage unit increases, and contracts when the temperature of the power storage unit decreases. Therefore, the sealed case is repeatedly subjected to a load with the expansion and contraction operation of the coolant. Since the metal case of Patent Document 1 is made of aluminum, fatigue characteristics are not sufficient.

  Accordingly, an object of the present invention is to increase the fatigue strength of a storage container that stores a liquid heat exchange medium that exchanges heat with a power storage unit.

In order to solve the above problems, the power storage device of the present invention, storage container and a top lid for covering (1) and the power storage unit, housing the power storage unit, and a container body opening is formed, the opening And a liquid heat exchange medium that is accommodated in the container and exchanges heat with the power storage body, and at least the upper lid of the container is made of an alloy composed of Al, Zn, and inevitable impurities, and has a mass. % Zn is characterized by a higher content than Al.

  (2) In the configuration of (1), the Al content is preferably set to 20 to 25% by mass.

  (3) In the configuration of (1) or (2), the container includes a container main body in which an opening is formed and an upper lid that covers the opening, and only the upper lid is made of the alloy. Features.

  (4) In the configuration of (3), the upper lid is attached to the container body via a fastening bolt. It is possible to protect the upper lid that receives a large load due to repeated loads.

  (5) In the configurations of (1) to (4), an insulating liquid can be used as the heat exchange medium. Thereby, two problems of prevention of electric leakage and improvement of fatigue strength of the container can be solved.

  (6) The power storage device of (1) to (5) can be mounted on a vehicle.

The present invention includes, as another aspect, a power storage unit, a container body in which a liquid heat exchange medium that exchanges heat with the power storage unit is formed, an opening is formed, and an upper lid that covers the opening. The container is characterized in that at least the upper lid of the container is made of an alloy composed of Al, Zn, and unavoidable impurities, and the content of Zn in mass% is higher than that of Al.

  According to the present invention, it is possible to increase the fatigue strength of the storage container that stores the liquid heat exchange medium that exchanges heat with the power storage unit.

Example 1
FIG. 1 is a cross-sectional view of the power storage device taken along the YZ plane, and the X axis, the Y axis, and the Z axis indicate three axes that are orthogonal to each other. 2A is a cross-sectional view of the cylindrical battery cut along the YZ plane, and FIG. 2B is a cross-sectional view of the power generation element.

  In FIG. 1, the power storage device 1 includes an assembled battery (power storage body) 12, an assembled battery 12, and a battery storage case (storage container) 13 that stores a coolant (liquid heat exchange medium) 23. The battery housing case 13 includes a case main body 13a and an upper lid 13b. The power storage device 1 of the present embodiment can be used for driving an electric vehicle, a hybrid vehicle, a fuel cell vehicle, or an auxiliary power source.

  The assembled battery 12 is configured by connecting a plurality of cylindrical batteries 122 in series. Cylindrical battery 122 is supported by a pair of battery folders 123 arranged to face each other. The battery folder 123 is formed in a flat plate shape.

Protruding terminal electrodes 131 and 132 are provided at both ends of each cylindrical battery 122.
In the pair of battery folders 123, through holes (not shown) for penetrating the terminal electrodes 131 and 132 are formed. The terminal electrodes 131 and 132 protrude from the end face of the battery folder 123 through this through hole.

  Screw grooves 131 a and 132 a are formed on the outer surfaces of the terminal electrodes 131 and 132. Cylindrical batteries 122 are connected in series via bus bars 124. The bus bar 124 is formed in a flat plate shape, and terminal electrodes 131 and 132 are inserted into openings (not shown) formed in the bus bar 124.

  By fastening the fastening nut 125 to the thread grooves 131a and 132a of the terminal electrodes 131 and 132, the bus bar 124 and the terminal electrodes 131 and 132 can be electrically and mechanically connected.

  The configuration of the cylindrical battery 122 will be described in detail with reference to FIG. A power generation element 135 is housed in the unit cell case 134 in a wound state.

  The power generation element 135 includes a positive electrode body 135b, a negative electrode body 135c, and a separator 135a disposed between the positive electrode body 135b and the negative electrode body 135c. Here, the positive electrode body 135b includes a current collector and a positive electrode layer formed on the surface of the current collector. The positive electrode layer can be formed on one side or both sides of the current collector. The positive electrode layer is a layer containing an active material, a conductive agent, or the like corresponding to the positive electrode.

  The negative electrode body 135c is composed of a current collector and a negative electrode layer formed on the surface of the current collector. The negative electrode layer can be formed on one side or both sides of the current collector. The negative electrode layer is a layer containing an active material, a conductive agent, or the like corresponding to the negative electrode.

  Note that an electrode (a so-called bipolar electrode) in which a positive electrode layer is formed on one surface of the current collector and a negative electrode layer is formed on the other surface of the current collector can also be used. In this embodiment, an electrolytic solution is used, but a solid electrolyte formed of particles can also be used. Examples of the solid electrolyte include a polymer solid electrolyte and an inorganic solid electrolyte.

Here, when the cylindrical battery 122 is a nickel-hydrogen battery, nickel oxide is used as the active material for the positive electrode layer, and MmNi _(5-xyz) Al _x is used as the active material for the negative electrode layer. Mn _y Co _z: can be used (Mm misch metal) hydrogen absorbing alloy or the like. When the cylindrical battery 122 is a lithium ion battery, a lithium-transition metal composite oxide can be used as the active material for the positive electrode layer, and carbon can be used as the active material for the negative electrode layer. As the conductive agent, acetylene black, carbon black, graphite, carbon fiber, or carbon nanotube can be used.

  Instead of the cylindrical battery 122, a capacitor (power storage unit) may be used. The capacitor is an electric double layer capacitor based on the principle of operation of an electric double layer generated at the interface between activated carbon and electrolyte. When activated carbon is used as a solid and an electrolytic solution (dilute sulfuric acid aqueous solution) is used as a liquid and brought into contact with each other, positive and negative electrodes are relatively distributed at very short intervals at the interface. When a pair of electrodes are immersed in an ionic solution and a voltage is applied to such an extent that electrolysis does not occur, ions are adsorbed on the surface of each electrode, and positive and negative electricity are stored (charging). When electricity is discharged to the outside, positive and negative ions leave the electrode and return to the neutralized state. Further, instead of the cylindrical battery 122, a prismatic battery (power storage unit) can be used.

  The coolant 23 accommodated in the battery housing case 13 is a substance having high specific heat, thermal conductivity and high boiling point, and does not corrode the battery housing case 13 and the assembled battery 12 and is not susceptible to thermal decomposition, air oxidation, electrolysis, or the like. Is suitable. Furthermore, an electrically insulating liquid is desirable in order to prevent a short circuit between the electrode terminals. For example, a fluorinated inert liquid can be used. As the fluorine-based inert liquid, Fluorinert, Novec HFE (hydrofluorether), and Novec 1230 manufactured by 3M can be used. In addition, a liquid other than the fluorine-based inert liquid (for example, silicon oil) can be used.

  The case body 13a is open on the upper side, and the upper lid 13b is placed on the upper end surface 135a of the case body 13a. Fastening holes (not shown) are formed at the four corners of the upper end surface 135a, and the upper lid 13b is fixed to the case body 13a by fastening the fastening bolts 14 to these fastening holes.

  Next, the composition of the battery housing case 13 will be described in detail. The battery housing case 13 is made of an alloy composed of Al, Zn, and inevitable impurities, and Zn is set to have a higher content than Al in mass%. Conventional battery housing cases are mainly Al-based alloys (alloys with 50% by mass or more of Al). Al-based alloys have advantages such as lightness, but are not sufficient in fatigue characteristics against repeated loads. Since there are few types of conventional battery housing cases that contain the coolant 23, the problem of receiving repeated loads from the coolant 23 does not exist in the first place.

  By increasing the Zn content rate than Al, the battery housing case 13 with high fatigue strength can be obtained. That is, when the coolant 23 expands and contracts, a repeated load is applied to the battery housing case 13, but the fatigue strength against this repeated load can be increased.

  Here, the Al content is preferably 20 to 25% by mass, and more preferably 22% by mass. SPZ (registered trademark) is known as an alloy (superplastic alloy) in which the Al content is 22% by mass and the balance is Zn and inevitable impurities. By using SPZ (registered trademark), the fatigue strength of the battery housing case 13 can be increased more effectively.

In addition, you may comprise a part of battery storage case 13 with the alloy of this invention. That is, when a region that is easily fatigued is specified in advance, only the region can be formed of the alloy of the present invention. For example, since the upper lid 13b is attached to the case main body 13a via the fastening bolts 14, the load due to repeated loads becomes larger. Therefore, at least the upper cover 13 b is composed of an alloy of the present invention.

It is sectional drawing of an electrical storage apparatus. (A) is sectional drawing of a cylindrical battery, (B) is sectional drawing of an electric power generation element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Power storage device 12 Assembly battery 13 Battery storage case 13a Case main body 13b Top cover 23 Cooling liquid

Claims (7)

A power storage unit;
A container body that houses the power storage unit and has an opening formed therein , and an upper lid that covers the opening.
And a non-storage container,
A liquid heat exchange medium housed in the container and performing heat exchange with the power storage unit;
At least the upper lid of the container is made of an alloy composed of Al, Zn, and unavoidable impurities, and the Zn content is higher than Al by mass%.   The power storage device according to claim 1, wherein the Al content is 20 to 25% by mass. The container is, power storage device according to only pre-Symbol lid to claim 1 or 2, characterized in that is constituted by the alloy.   The power storage device according to claim 3, wherein the upper lid is attached to the container body via a fastening bolt.   The power storage device according to claim 1, wherein the heat exchange medium is an insulating liquid.   A vehicle comprising the power storage device according to claim 1. A storage container containing a power storage unit, a liquid heat exchange medium that exchanges heat with the power storage unit, and having a container body in which an opening is formed, and an upper lid that covers the opening , the storage container The at least said upper lid is comprised with the alloy which consists of Al, Zn, and an unavoidable impurity, and the content rate of Zn is higher than Al by mass%, The storage container characterized by the above-mentioned.

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