Patent Description:
A power supply device such as a battery module or a battery pack including a plurality of battery cells is used as a power source for a vehicle such as a hybrid vehicle or an electric car, a power source for a power storage system for a factory, a home, or the like (see PTL <NUM>, for example).

A battery cell constituting such a power supply device is provided with a gas discharge valve that opens to release gas when the pressure inside of the outer covering can becomes high at the time of abnormality. When the pressure of the inside becomes high for some reason such as thermal runaway in any battery cell, high-temperature, high-pressure gas is released from the gas discharge valve.

In order to prevent such a situation, a configuration in which a baffle plate is provided in a gas duct as shown in a transverse sectional view of <FIG> has been proposed. According to this structure, by bending the gas discharge path, it becomes possible to reduce the momentum and also lower the temperature to safely discharge the gas to the outside.

However, since the pressure of the gas is high, as shown in the transverse sectional view of <FIG>, as a result of the duct being deformed by the gas pressure, a gas discharge path avoiding the baffle plate is formed, and there has been a possibility that the gas is discharged to the outside of the power supply device while being at a high pressure and temperature.

Patent literature <CIT> discloses a battery module including a release mechanism for releasing a gas from a battery to outside the case with a flat plate that allows the gases released from the cells to go through the flat plate and pass through the duct formed between the flat plate and the partition. Patent literature <CIT> discloses a power supply apparatus with a plurality of battery blocks and an exhaust duct which includes opening windows at a position facing the battery block side opening window. Furthermore, there is a foreign matter movement preventing piece on the path of the exhaust duct which prevents the movement of foreign matter while still allowing the gas to be discharged through the exhaust duct.

The object of the present invention is to provide a power supply device capable of safely discharging gas to the outside when the gas is discharged from a battery cell, a vehicle and an electrical storage device equipped with power supply device.

A power supply device according to the present invention includes: a battery stack in which a plurality of battery cells are stacked, each battery cell having a gas discharge valve that opens when an internal pressure of an outer covering can rises and an electrode terminal formed on an upper surface; a first cover that is provided on an upper surface of the battery stack and opens at a position corresponding to the gas discharge valve; and a second cover that is provided on an upper surface of the first cover and defines a gas duct with the first cover, in which the gas duct forms a baffle plate between the first cover and a second cover, and the power supply device further includes a metallic third cover that is provided on an upper surface of the second cover and abuts on an upper surface of the second cover.

According to a power supply device according to the present invention, even if a high-temperature, high-pressure gas is discharged from a gas discharge valve, by reinforcing the upper surface of the second cover with the metallic third cover, it is possible to suppress deformation of the second cover, and avoid a situation in which an unintended gas discharge path avoiding a baffle plate is formed.

Exemplary embodiments of the present invention may be specified by the following configurations.

A power supply device according to an exemplary embodiment of the present invention further includes, in addition to the above configuration, an end plate that covers a side surface of the battery stack, and the third cover is fixed to the end plate. The above configuration makes it possible to firmly fix the third cover to the power supply device using the end plate, and the third cover can prevent deformation of the second cover.

In a power supply device according to another exemplary embodiment of the present invention, in addition to any of the configurations described above, the battery stack includes a pair of fastening members that fasten the end plates to each other on both side surfaces of the battery stack, and the battery stack fastens the plurality of battery cells by the pair of fastening members and a third cover on an upper surface. With the above configuration, in addition to the fastening member that fastens the plurality of battery cells in a stack state, the third cover on the upper surface can also maintain the fastened state, and therefore the fastened state of the battery stack can be maintained more firmly by using the third cover also as a fastening member.

A power supply device according to another exemplary embodiment of the present invention further includes, in addition to any of the configurations described above, a bus bar that connects electrode terminals of the battery cells constituting the battery stack; and a total terminal strip that is connected to the bus bar, in which the third cover forms an exposure part that exposes the total terminal strip. With the above configuration, it is possible to secure the insulation distance by separating from the total terminal strip while using the metallic third cover, and to avoid the possibility of occurrence of an unintended short circuit.

Furthermore, in a power supply device according to another exemplary embodiment of the present invention, in addition to any of the configurations described above, the third cover forms a bead. With the above configuration, the strength can be improved by simple processing of forming a bead on the third cover.

Furthermore, in a power supply device according to another exemplary embodiment of the present invention, in addition to any of the configurations described above, the first cover and the second cover are made of resin.

An electric vehicle according to another exemplary embodiment of the present invention includes any of the above power supply devices, a motor for travelling to which the power supply device supplies electric power, a vehicle body equipped with the power supply device and the motor, and a wheel driven by the motor to cause the vehicle body to travel.

Furthermore, an electrical storage device according to another exemplary embodiment of the present invention includes any of the above power supply devices and a power supply controller that controls charging and discharging of the power supply device, in which the power supply controller enables charging of the plurality of battery cells with electric power from outside, and controls charging to be performed on the plurality of battery cells.

Exemplary embodiments of the present invention will be described with reference to the drawings. However, the exemplary embodiments described below are examples for embodying the technical idea of the present invention, and the present invention is not limited to the following. In the present description, members indicated in the claims are not specified at all to the members of the exemplary embodiments. In particular, the dimensions, materials, shapes, and relative arrangement of the constituent members described in the exemplary embodiments are not intended to limit the scope of the present invention only thereto unless otherwise specified and are merely illustrative examples. The sizes and positional relationships of the members shown in the drawings may be exaggerated for clarity of description. In the following description, the same names and reference marks indicate the same or similar members, and detailed description will be appropriately omitted. The elements constituting the present invention may be configured such that the plurality of elements are constituted of the same members to form one member that functions as a plurality of elements, or conversely, the function of one member can be shared and achieved by a plurality of members. The description in some examples or exemplary embodiments may be applied to other examples, exemplary embodiments, and the like.

The power supply device according to the exemplary embodiments is used in various applications including a power source to be equipped on a hybrid vehicle, an electric car, or other electric vehicles to supply electric power to a drive motor, a power source that stores power generated by natural energy such as solar power generation and wind power generation, and a power source for storing midnight electric power, and in particular, used as a power source suitable for large-power, large-current applications. In the following example, the exemplary embodiments applied to a power supply device for driving an electric vehicle will be described.

Power supply device <NUM> according to the first exemplary embodiment of the present invention is shown in <FIG> and <FIG>. In these figures, <FIG> is an exploded perspective view of power supply device <NUM> according to the first exemplary embodiment, and <FIG> is an exploded perspective view of power supply device <NUM> shown in <FIG>.

Power supply device <NUM> shown in these figures includes battery stack <NUM> in which the plurality of battery cells <NUM> are stacked, a pair of end plates <NUM> covering both side end surfaces of battery stack <NUM>, a plurality of fastening members <NUM> for fastening end plates <NUM> to each other, and cover assembly <NUM> provided on an upper surface of battery stack <NUM>.

Fastening member <NUM> is formed into a plate shape extending in a stack direction of the plurality of battery cells <NUM>. Fastening members <NUM> are arranged on opposite side surfaces of battery stack <NUM> to fasten end plates <NUM> to each other.

As shown in <FIG>, battery stack <NUM> includes the plurality of battery cells <NUM> each including positive and negative electrode terminals <NUM>, and bus bars connected to electrode terminals <NUM> of the plurality of battery cells <NUM> to connect the plurality of battery cells <NUM> in parallel and in series. The plurality of battery cells <NUM> are connected in parallel and in series through the bus bars. Battery cells <NUM> are chargeable and dischargeable secondary batteries. Power supply device <NUM> includes the plurality of battery cells <NUM> connected in parallel to form a parallel battery group, and a plurality of parallel battery groups are connected in series to allow many battery cells <NUM> to be connected in parallel and in series. In power supply device <NUM> shown in <FIG>, the plurality of battery cells <NUM> are stacked to form battery stack <NUM>. The pair of end plates <NUM> are arranged on both end surfaces of battery stack <NUM>. Ends of fastening members <NUM> are fixed to end plates <NUM> to fix, in a state of being pressurized, battery cells <NUM> in the stack state.

As shown in <FIG>, battery cell <NUM> are each a prismatic battery having a width larger than the thickness, in other words, a width smaller than the width, and are stacked in the thickness to form battery stack <NUM>. Battery cell <NUM> can be, for example, a lithium ion secondary battery. The battery cell can be any chargeable secondary battery such as a nickel hydride battery and a nickel cadmium battery. Battery cell <NUM> houses positive and negative electrode plates in outer covering can 1a having a sealed structure together with an electrolyte solution. Outer covering can 1a includes a metal sheet such as aluminum or an aluminum alloy press-molded into a prismatic shape, and has an opening that is hermetically sealed with sealing plate 1b. Sealing plate 1b is made of the aluminum or aluminum alloy same as prismatic outer covering can 1a, and positive and negative electrode terminals <NUM> are fixed to both ends of sealing plate 1b. Sealing plate 1b is provided with, between positive and negative electrode terminals <NUM>, gas discharge valve 1c, which is a safety valve that opens in response to a change in pressure inside each battery cell <NUM>.

The plurality of battery cells <NUM> are stacked such that the thickness direction of each battery cell <NUM> is the stack direction to constitute battery stack <NUM>. At this time, the output of battery stack <NUM> can be increased by making the number of stack layers larger than usual. In such a case, battery stack <NUM> becomes long by being extended in the stack direction. In battery cell <NUM>, terminal surfaces 1X provided with positive and negative electrode terminals <NUM> are arranged on the same plane, and the plurality of battery cells <NUM> are stacked to be battery stack <NUM>. Then, an upper surface of battery stack <NUM> is a surface provided with gas discharge valves 1c of the plurality of battery cells <NUM>.

In battery cell <NUM>, as shown in <FIG> and the like, with sealing plate 1b, which is a top surface, as terminal surface 1X, positive and negative electrode terminals <NUM> are fixed to both ends of terminal surface 1X. Electrode terminal <NUM> has a protrusion having a circular columnar shape. However, the protrusion is not necessarily in a circular columnar shape, and can be in a polygonal columnar shape or an elliptic columnar shape.

Positive and negative electrode terminals <NUM> fixed to sealing plate 1b of battery cell <NUM> are positioned where the positive electrode and the negative electrode become bilaterally symmetrical. Consequently, as shown in <FIG>, battery cells <NUM> are horizontally flipped and stacked, and electrode terminals <NUM> of a positive electrode and a negative electrode that are adjacently close to each other are connected by a bus bar, so that adjacent battery cells <NUM> can be connected in series. Note that the present invention does not specify the number and connection state of the battery cells constituting the battery stack. The number and connection state of the battery cells constituting the battery stack may be modified in various manners, inclusive of other exemplary embodiments described later.

The plurality of battery cells <NUM> are stacked such that the thickness of each battery cell <NUM> aligns with the stack direction to constitute battery stack <NUM>. In battery stack <NUM>, the plurality of battery cells <NUM> are stacked such that terminal surface 1X provided with positive and negative electrode terminals <NUM> and sealing plate 1b in <FIG> become flush with each other.

In battery stack <NUM>, insulating spacer <NUM> may be interposed between battery cells <NUM> stacked adjacently to each other. Insulating spacer <NUM> is produced in the form of a thin plate or sheet with an insulating material such as resin. Insulating spacer <NUM> has a plate shape that is substantially equal in size to an opposed face of battery cell <NUM>. Such insulating spacer <NUM> can be stacked between battery cells <NUM> adjacent to each other to insulate adjacent battery cells <NUM> from each other. As a spacer arranged between adjacent battery cells, it is possible to use a spacer having a shape in which a flow path for a cooling gas is formed between the battery cell and the spacer. It is also possible to cover a surface of battery cell <NUM> with an insulating material. For example, the surface of the outer covering can excluding the electrode terminal part of the battery cell may be covered with a shrink film such as a PET resin. In this case, the insulating spacer may be omitted. Although a power supply device including a large number of battery cells connected in parallel and series includes an insulating spacer interposed between battery cells connected in series to each other, no voltage difference occurs between adjacent outer covering cans in battery cells connected in parallel to each other, and therefore the insulating spacer between these battery cells can be eliminated.

Power supply device <NUM> shown in <FIG> includes end plates <NUM> arranged on both end surfaces of battery stack <NUM>. Between end plate <NUM> and battery stack <NUM>, end surface spacer <NUM> may be interposed to insulate them. End surface spacer <NUM> can also be produced in the form of a thin plate or sheet with an insulating material such as resin.

In power supply device <NUM> according to the first exemplary embodiment, in battery stack <NUM> in which the plurality of battery cells <NUM> are stacked on each other, electrode terminals <NUM> of the plurality of battery cells <NUM> adjacent to each other are connected by the bus bar to connect the plurality of battery cells <NUM> in parallel and in series. A bus bar holder may be disposed between battery stack <NUM> and the bus bar. Use of the bus bar holder allows the plurality of bus bars to be arranged at fixed positions on the upper surface of the battery stack while insulating the plurality of bus bars from each other and insulating terminal surface 1X of the battery cell and the bus bar. Cover assembly <NUM> described later may be integrated with the bus bar holder.

The bus bar is manufactured into a predetermined shape by cutting and processing a metal sheet. As the metal sheet configuring the bus bar, metal that is low in electrical resistance and light in weight, such as an aluminum sheet, a copper sheet, or an alloy of these metals can be used. However, as the metal sheet for the bus bar, other types of metal that are low in electrical resistance and light in weight or an alloy of them can be used.

As shown in <FIG>, end plates <NUM> are arranged at both ends of battery stack <NUM> and fastened via the pair of right and left fastening members <NUM> arranged along the both side surfaces of battery stack <NUM>. End plates <NUM> are arranged at both ends of battery stack <NUM> in the stack direction of battery cells <NUM> and outside end surface spacer <NUM> to sandwich battery stack <NUM> from both ends.

Fastening member <NUM> has both ends fixed to end plates <NUM> arranged on both end surfaces of battery stack <NUM>. End plates <NUM> are fixed by the plurality of fastening members <NUM> to fasten battery stack <NUM> in the stack direction. As shown in <FIG> and the like, each fastening member <NUM> is made of metal having a predetermined width and a predetermined thickness along the side surface of battery stack <NUM>, and is arranged opposite to both side surfaces of battery stack <NUM>. A metal sheet of iron or the like, preferably a steel sheet, can be used as fastening member <NUM>. Fastening member <NUM> made of a metal sheet is bent by press molding or the like to be formed into a predetermined shape.

Fastening member <NUM> has an upper and lower parts of plate-shaped fastening main surface 15a bent in a U-shape to form bent pieces 15b. Upper and lower bent pieces 15b cover upper and lower surfaces of battery stack <NUM> from the corners on the right and left side surfaces of battery stack <NUM>. Fastening member <NUM> is fixed to an outer peripheral surface of end plate <NUM> by screwing bolts 15f into a plurality of screw holes opened in fastening main surface 15a. Fastening main surface 15a and end plate <NUM> are not necessarily fixed by screwing with bolts, and may be fixed with pins, rivets, or the like.

Power supply device <NUM> having a large number of battery cells <NUM> stacked is configured such that the plurality of battery cells <NUM> are constrained by coupling, by means of fastening members <NUM>, end plates <NUM> arranged at the both ends of battery stack <NUM> including the plurality of battery cells <NUM>. By constraining the plurality of battery cells <NUM> via end plates <NUM> and fastening members <NUM> that have high rigidity, it is possible to suppress malfunction or the like caused by swelling, deformation, relative displacement, or vibration of battery cells <NUM> due to charging and discharging or degradation.

Insulating sheet <NUM> is interposed between fastening member <NUM> and battery stack <NUM>. Insulating sheet <NUM> is made of a material having insulating properties, such as a resin or the like, and insulates between fastening member <NUM> made of metal and the battery cells. Insulating sheet <NUM> shown in <FIG> and the like includes flat plate <NUM> covering the side surface of battery stack <NUM>, and bent covered part <NUM> provided on each of an upper part and a lower part of flat plate <NUM>. Bent covered parts <NUM> are each bent from flat plate <NUM> in a U-shape and folded so as to cover bent pieces 15b of fastening member <NUM>. Due to this, by being covered with the insulating bent covered part from the upper surface to the side surface and the lower surface, bent piece 15b can avoid unintended conduction between battery cell <NUM> and fastening member <NUM>.

Bent piece 15b presses the upper surfaces and the lower surfaces of battery cells <NUM> of battery stack <NUM> via bent covered part <NUM>. This enables each battery cell <NUM> to be held in the height direction by being pressed by bent piece 15b in the up-down direction, and each battery cell <NUM> to be maintained so as not to be displaced in the up-down direction even if vibration, impact, or the like is applied to battery stack <NUM>.

The insulating sheet can be unnecessary in a case where the battery stack and the surface of the battery stack are insulated, for example, in a case where the battery cells are housed in an insulating case or covered with a heat-shrinkable film made of resin, in a case where an insulating paint or coating is applied to the surface of the fastening member, or in a case where the fastening member is made of an insulating material. Insulating sheet <NUM> may also have bent covered part <NUM> formed only on the upper end in a case where insulation from bent piece 15b of fastening member <NUM> near the lower surface of battery stack <NUM> does not need to be taken into consideration. This applies to, for example, a case where battery cells <NUM> are covered with a heat-shrinkable film. Insulating sheet <NUM> may also be configured to serve as the bus bar holder holding the bus bar described above.

Power supply device <NUM> is provided with cover assembly <NUM> on the upper surface of battery stack <NUM>. Cover assembly <NUM> configures a gas discharge path for discharging a high-temperature, high-pressure gas to the outside of power supply device <NUM> when this gas is discharged from any of battery cells <NUM> constituting battery stack <NUM>. Note that cover assembly <NUM> may also be configured to serve as a bus bar holder that holds the bus bar.

As shown in the schematic sectional view of <FIG>, cover assembly <NUM> includes first cover <NUM>, second cover <NUM>, and third cover <NUM>. First cover <NUM> is provided on the upper surface of battery stack <NUM>. First cover <NUM> has gas introduction port <NUM> opened at a position corresponding to gas discharge valve 1c of battery cell <NUM> constituting battery stack <NUM>.

Second cover <NUM> is provided on the upper surface of first cover <NUM>, and defines gas duct <NUM> with first cover <NUM>. In gas duct <NUM>, baffle plate <NUM> is formed between first cover <NUM> and second cover <NUM>. Due to this, even if high-temperature, high-pressure gas GS is discharged from gas discharge valve 1c, gas GS is prevented from proceeding until gas GS is discharged toward the side surface of battery stack <NUM>, the pressure is lowered, the temperature is lowered, and gas GS is safely discharged to the outside.

Furthermore, third cover <NUM> is provided on the upper surface of second cover <NUM>, and abuts on the upper surface of second cover <NUM>. Third cover <NUM> is made of metal. With such a configuration, even if high-temperature, high-pressure gas GS is discharged from gas discharge valve 1c, by reinforcing the upper surface of second cover <NUM> with metallic third cover <NUM>, it is possible to suppress deformation of second cover <NUM>, and avoid a situation in which an unintended gas discharge path avoiding a baffle plate <NUM> is formed.

As in power supply device <NUM> according to a comparative example shown in the schematic sectional view of <FIG>, by providing a large number of baffle plates <NUM> in gas duct <NUM> and bending the gas discharge path so that so as to discharge gas GS along baffle plates <NUM>, it becomes possible to reduce the momentum and also lower the temperature to safely discharge the gas to the outside.

However, when the pressure of gas GS to be discharged is high, as shown in the transverse sectional view of <FIG>, as a result of gas duct <NUM> being deformed by the gas pressure, a gas discharge path avoiding baffle plate <NUM> is formed, and it is conceivable that gas GS is discharged to the outside of the power supply device at a high pressure and temperature. In particular, there has been a limit in resistance against deformation in a case where first cover <NUM> and second cover <NUM> constituting gas duct <NUM> are made of resin from the viewpoint of insulation and the like.

On the other hand, in power supply device <NUM> according to the present exemplary embodiment, by covering the upper surface of second cover <NUM> with metallic third cover <NUM> as shown in <FIG>, it is possible to suppress deformation due to gas pressure.

Third cover <NUM> can also improve rigidity against swelling of the battery cell. Since battery cell <NUM> expands due to charging and discharging, such deformation is accumulated, and the overall length of battery stack <NUM> also changes. As shown in <FIG>, end plate <NUM> is arranged on the end surface of battery stack <NUM> so as to oppose such a swelling force of battery stack <NUM>, and end plates <NUM> are fastened to each other by fastening member <NUM> on the side surface of battery stack <NUM>. By fixing third cover <NUM> to end plate <NUM>, it is possible to improve the rigidity against the swelling force of the battery cell also on the upper surface of battery stack <NUM>. On the other hand, first cover <NUM> and second cover <NUM> are made of resin that ensures insulation and facilitates formation of baffle plate <NUM> inside gas duct <NUM>, and each cover is assigned with a different function and made of a material corresponding to the function assigned to each cover.

Hereinafter, a specific configuration of cover assembly <NUM> will be described with reference to <FIG>. In these figures, <FIG> is an exploded perspective view showing a state in which reinforcement cover <NUM> is removed from cover assembly <NUM> of <FIG>, <FIG> is an exploded perspective view of <FIG>, <FIG> is an exploded perspective view of <FIG> as viewed obliquely from below, <FIG> is an exploded perspective view showing a state in which reinforcement cover <NUM> is removed from power supply device <NUM> of <FIG>, <FIG> is a plan view of power supply device <NUM> of <FIG> with reinforcement cover <NUM> in a transparent state, and <FIG> is a sectional view with an enlarged view of a main part taken along line XI-XI in <FIG>. Cover assembly <NUM> shown in these figures includes lower cover <NUM>, upper cover <NUM>, and reinforcement cover <NUM>. The lower cover corresponds to first cover <NUM> described above, upper cover <NUM> corresponds to second cover <NUM>, and reinforcement cover <NUM> corresponds to third cover <NUM>.

Lower cover <NUM> is provided on the upper surface of battery stack <NUM>, and defines a first gas duct communicating with gas discharge valve 1c. As shown in <FIG> and <FIG>, lower cover <NUM> has gas introduction port <NUM> opened at a position corresponding to gas discharge valve 1c of battery cell <NUM>. As shown in <FIG>, <FIG>, <FIG>, and the like, lower cover <NUM> has a large number of baffle plates <NUM>, and by baffle plates <NUM> changing the travelling direction until the high-temperature, high-pressure gas is discharged, the momentum is reduced and the temperature is lowered. The gas discharge path is provided not only in the stack direction of battery cells <NUM> but also in a direction intersecting the stack direction. Lower cover <NUM> is made of resin having excellent insulation properties, for example, polycarbonate.

The upper surface of lower cover <NUM> is provided with intermediate plate <NUM>. Intermediate plate <NUM> is provided at the center in the width of battery stack <NUM>, and is disposed so as to oppose gas discharge valve 1c. Intermediate plate <NUM> is made of a material excellent in strength, for example, metal. Due to this, even if a high-temperature, high-pressure gas is discharged from the gas discharge path, the gas is received by metallic intermediate plate <NUM> higher in strength than the resin cover, so that a situation in which the gas is directly ejected through power supply device <NUM> is avoided.

Upper cover <NUM> is provided on the upper surface of lower cover <NUM>, and defines a second gas duct on the upper surface of the first gas duct. Upper cover <NUM> is made of resin. A plurality of communication holes <NUM> through which the first gas duct and the second gas duct communicate with each other are formed on the upper surface of upper cover <NUM>. Thus, by giving gas duct <NUM> a two-layer structure of the first gas duct and the second gas duct, even if gas is discharged from the battery cell, the gas is branched into the first gas duct and the second gas duct, and is discharged in a dispersed manner, so that it is possible to suppress a situation in which the gas discharged to the outside is ignited while avoiding the gas from staying inside the power supply device. By providing a plurality of exhaust ports for gas discharge, it is possible to reduce the sectional area per one, and it is possible to reduce the risk of ignition even in a case where a high-temperature gas is discharged.

It is preferable that communication holes <NUM> are not opened corresponding to all the battery cells, but are discretely opened so as to serve the plurality of battery cells. In the example of <FIG> and the like, communication holes <NUM> are opened at three places in the stack direction with respect to battery stack <NUM> in which <NUM> battery cells <NUM> are stacked.

It is preferable that communication holes <NUM> are provided not at positions opposed to gas discharge valve 1c but at positions offset from gas discharge valve 1c. By not directly opening communication holes <NUM> with respect to gas discharge valve 1c, it is possible to easily disperse the gas. Gas discharge valve 1c is provided at the center of sealing plate 1b of battery cell <NUM> in the example shown in <FIG>. On the other hand, as shown in <FIG> and the like, communication holes <NUM> are opened at positions corresponding to the right and left of sealing plate 1b of battery cell <NUM>.

Communication hole <NUM> is preferably formed in a slit shape. The path area of the second gas duct can be set by adjusting the width and length of the slit, the height of the second gas duct, and the like, and the amount of gas to be discharged can be controlled. In the example of <FIG> and the like, the height of the second gas duct is defined by the height of communication rib <NUM> described later.

Upper cover <NUM> is provided with communication rib <NUM> protruding toward reinforcement cover <NUM> around communication hole <NUM>. This makes it possible to block a situation in which the path for introducing gas into the second gas duct is obstructed. In a configuration provided with no communication rib, as in power supply device <NUM> shown in the schematic sectional view of <FIG>, it is conceivable that when high pressure gas is discharged from gas discharge valve 1c, the periphery of communication hole <NUM> opened on upper cover <NUM> is deformed by the pressure of the gas, and the gas discharge path is closed. In this state, the gas is not guided to the second gas duct, and the gas cannot be dispersed and discharged through the second gas duct. On the other hand, as shown in the schematic sectional view of <FIG>, by providing communication rib <NUM> around communication hole <NUM>, it becomes possible to block deformation around communication hole <NUM>, secure an opening end to the second gas duct, and guide the high-pressure gas to the second gas duct.

Communication rib <NUM> is provided on not the entirety but a part of circumference of communication hole <NUM> so as not to block inflow of the gas into the second gas duct. It is preferable that as shown in the plan view of <FIG>, a pair of communication ribs <NUM> are provided so as to oppose both sides of communication hole <NUM>. In a case of communication hole <NUM> in a slit shape, it is preferable to arrange the pair of communication ribs <NUM> so as to intersect with the long direction of the slit. In this example, communication rib <NUM> is integrally molded with resin upper cover <NUM>. This configuration makes it possible to position and easily form communication rib <NUM> around communication hole <NUM>. However, it is needless to say that the communication rib may be provided near the reinforcement cover side. In particular, by protruding the communication rib on the metallic reinforcement cover by punching or the like, it is possible to form a communication rib that is stronger and hardly deformed.

Furthermore, upper cover <NUM> is provided with partition rib <NUM> that partitions between the plurality of communication holes <NUM> adjacent to each other. This makes it possible to partition the second gas duct for each communication hole <NUM>, and to cause the high-pressure gas introduced into the second gas duct from communication hole <NUM> not to be discharged in a concentrated manner at one place.

In the example of <FIG> and the like, battery stack <NUM> in which <NUM> battery cells <NUM> are stacked is partitioned into three for every four cells, and further divided into two sections on the right and left of battery cell <NUM>, so that battery stack <NUM> is divided into a total of six partitions. In the example of <FIG>, the partition rib protrudes on the upper surface of upper cover <NUM>, but the present invention is not limited to this configuration, and it goes without saying that the partition rib may protrude near the reinforcement cover, for example.

Furthermore, the gas discharge path is preferably provided not only in the stack direction of battery cells <NUM> but also in a direction intersecting the stack direction. By discharging the gas also in the intersecting direction in this manner, it is possible to efficiently discharge the gas to the outside of the power supply device and enhance safety. In the example of <FIG>, a gas discharge path is formed in each of the first gas duct and the second gas duct so that gas is discharged also in the up-down direction in the figure.

Reinforcement cover <NUM> is provided on the upper surface of upper cover <NUM>. The second gas duct is formed between reinforcement cover <NUM> and upper cover <NUM>. Reinforcement cover <NUM> abuts on the upper surface of upper cover <NUM> via communication rib <NUM>. With such a configuration, even if a high-temperature, high-pressure gas is discharged from gas discharge valve 1c, deformation of upper cover <NUM> can be suppressed by reinforcing the upper surface of upper cover <NUM> with metal reinforcement. In particular, when upper cover <NUM> is deformed, there is a possibility that an unintended gas discharge path avoiding baffle plate <NUM> is formed, but such a situation can be avoided by blocking upper cover <NUM> from deforming with reinforcement cover <NUM>.

Reinforcement cover <NUM> is fixed to the upper surface of end plate <NUM> with bolt <NUM> or the like as shown in <FIG>. This makes it possible to, in addition to fastening the side surface of battery stack <NUM> by fastening member <NUM>, fasten also the upper surface of battery stack <NUM> by reinforcement cover <NUM>, and increase the rigidity of pressing the end surface of battery stack <NUM> by end plate <NUM>. In other words, reinforcement cover <NUM> is used also as an additional fastening member.

Reinforcement cover <NUM> may form bead <NUM> in order to increase rigidity. In power supply device <NUM> according to the second exemplary embodiment shown in the perspective view of <FIG>, bead <NUM> is formed at the center in the long direction of reinforcement cover <NUM>. The strength can be improved by simple processing of forming bead <NUM> on metal sheet reinforcement cover <NUM> in this manner.

As described above, electrode terminals <NUM> of each battery cell <NUM> constituting battery stack <NUM> are connected to each other by the bus bar. The power supply device includes total terminal strip <NUM> that draws a total output of the plurality of battery cells <NUM> connected in series and in parallel via the bus bar. Total terminal strip <NUM> is made of a metal sheet excellent in conductivity. In order to insulate metallic reinforcement cover <NUM> and total terminal strip <NUM> from each other, total terminal strip <NUM> is exposed from reinforcement cover <NUM> as shown in <FIG> and <FIG>. Therefore, reinforcement cover <NUM> forms exposure part <NUM> that exposes total terminal strip <NUM>. This makes it possible to secure the insulating distance by separating, while using, metallic reinforcement cover <NUM> from total terminal strips <NUM> also made of metal, and possible to avoid the possibility of occurrence of an unintended short circuit.

Exposure part <NUM> can be an exposed cutout in which corner parts of reinforcement cover <NUM> are cut out so as to expose total terminal strip <NUM> as shown in <FIG> and the like. This enhances the safety by separating metallic reinforcement cover <NUM> and total terminal strip <NUM> in the horizontal plane so as not to overlap each other. Alternatively, exposure part <NUM> may be an exposure window that exposes the total terminal strip.

In the example of <FIG> and the like, total terminal strip <NUM> is provided on one side surface (lower side in the figure) of the upper surface of end plate <NUM>. Exposure part <NUM> may be formed only at the lower corner of the end of reinforcement cover <NUM> accordingly, or may be provided on both sides of the end as shown in <FIG> and the like. This makes it possible to attach reinforcement cover <NUM> even if the reinforcement cover is turned in the right-left direction, and the assembling workability is improved.

Power supply device <NUM> described above can be used as a power source for a vehicle that supplies electric power to a motor that causes an electric vehicle to travel. As an electric vehicle equipped with power supply device <NUM>, electric vehicles such as a hybrid vehicle and a plug-in hybrid vehicle that travel with both an engine and a motor, or an electric car that travels only with a motor can be used, and the power supply device is used as a power source for these vehicles. An example will be described in which a large-capacity, high-output power supply device where a large number of power supply devices <NUM> described above are connected in series or in parallel in order to obtain electric power for driving an electric vehicle and a necessary controlling circuit is further added is constructed.

<FIG> shows an example in which power supply device <NUM> is equipped on a hybrid vehicle that travels with both an engine and a motor. Vehicle HV equipped with power supply device <NUM> shown in this figure includes vehicle body <NUM>, engine <NUM> and motor for travelling <NUM> that cause vehicle body <NUM> to travel, wheels <NUM> driven by engine <NUM> and motor for travelling <NUM>, power supply device <NUM> that supplies electric power to motor <NUM>, and generator <NUM> that charges the battery of power supply device <NUM>. Power supply device <NUM> is connected to motor <NUM> and generator <NUM> via DC/AC inverter <NUM>. Vehicle HV travels with both motor <NUM> and engine <NUM> while charging and discharging the battery of power supply device <NUM>. Motor <NUM> is driven in a region where engine efficiency is low, for example, during acceleration or low-speed travelling, and causes the vehicle to travel. Motor <NUM> is driven by electric power supplied from power supply device <NUM>. Generator <NUM> is driven by engine <NUM> or driven by regenerative braking when the vehicle is braked, and charges the battery of power supply device <NUM>. As shown in <FIG>, vehicle HV may include charging plug <NUM> for charging power supply device <NUM>. By connecting charging plug <NUM> to an external power source, it is possible to charge power supply device <NUM>.

<FIG> shows an example in which power supply device <NUM> is equipped on an electric car that travels only with a motor. Vehicle EV equipped with power supply device <NUM> shown in this figure includes vehicle body <NUM>, motor for travelling <NUM> that causes vehicle body <NUM> to travel, wheels <NUM> that are driven by motor <NUM>, power supply device <NUM> that supplies electric power to motor <NUM>, and generator <NUM> that charges the battery of power supply device <NUM>. Power supply device <NUM> is connected to motor <NUM> and generator <NUM> via DC/AC inverter <NUM>. Motor <NUM> is driven by electric power supplied from power supply device <NUM>. Generator <NUM> is driven by the energy at the time of applying regenerative braking to vehicle EV, and charges the battery of power supply device <NUM>. Vehicle EV includes charging plug <NUM>, and power supply device <NUM> can be charged by connecting charging plug <NUM> to an external power source.

Furthermore, the present invention does not limit the application of the power supply device to a power source for a motor that causes a vehicle to travel. The power supply device according to the exemplary embodiments can also be used as a power source for an electrical storage device that stores electricity by charging a battery with electric power generated by photovoltaic power generation, wind power generation, and the like. <FIG> shows an electrical storage device that stores electricity by charging the battery of power supply device <NUM> with solar battery <NUM>.

The electrical storage device shown in <FIG> charges the batteries of power supply device <NUM> with electric power generated by solar battery <NUM> that is disposed on a roof or a rooftop of building <NUM> such as a house or a factory. This electrical storage device charges the battery of power supply device <NUM> at charging circuit <NUM> with solar battery <NUM> as a charging power source, and then supplies electric power to load <NUM> via DC/AC inverter <NUM>. Thus, this electrical storage device includes a charge mode and a discharge mode. In the electrical storage device shown in the figure, DC/AC inverter <NUM> and charging circuit <NUM> are connected to power supply device <NUM> via discharging switch <NUM> and charging switch <NUM>, respectively. On/off of discharging switch <NUM> and charging switch <NUM> is switched by power supply controller <NUM> of the electrical storage device. In the charge mode, power supply controller <NUM> turns on charging switch <NUM> and turns off discharging switch <NUM> to allow charging from charging circuit <NUM> to power supply device <NUM>. When charging is completed and the battery is fully charged or in a state where a capacity of a predetermined value or more is charged, power supply controller <NUM> turns off charging switch <NUM> and turns on discharging switch <NUM> to switch the mode to the discharge mode and allows discharging from power supply device <NUM> to load <NUM>. Where necessary, supply of electric power to load <NUM> and charging of power supply device <NUM> can be simultaneously carried out by turning on charging switch <NUM> and turning on discharging switch <NUM>.

Although not illustrated, the power supply device can also be used as a power source for an electrical storage device that stores electricity by charging a battery using midnight electric power at night. The power supply device that is charged with midnight electric power is charged with the midnight electric power that is surplus electric power generated by a power station, and outputs the electric power during the daytime when an electric power load increases, which can limit peak electric power during the daytime to a small value. The power supply device can also be used as a power source charged with both output of a solar battery and the midnight electric power. Effectively using both electric power generated by the solar battery and the midnight electric power, this power supply device can efficiently perform power storage in consideration of weather and electric power consumption.

The power storage system as described above can be suitably used in applications including a backup power supply device that can be equipped on a computer server rack, a backup power supply device for wireless base stations for cellular phones and the like, an electrical storage device combined with a solar battery such as a power storage power source for homes and factories or a power source for street lights, and a backup power source for traffic lights and traffic indicators on roads.

Claim 1:
A power supply device (<NUM>, <NUM>) comprising:
a battery stack (<NUM>) in which battery cells (<NUM>) are stacked, each of battery cells (<NUM>) including a gas discharge valve (1c) that opens when an internal pressure of an outer covering can (1a) rises and an electrode disposed on an upper surface;
a first cover (<NUM>) that is provided on an upper surface of the battery stack (<NUM>) and opens at a position corresponding to the gas discharge valve (1c) of each of the battery cells (<NUM>); and
a second cover (<NUM>) that is provided above an upper surface of the first cover (<NUM>) and defines a gas duct (<NUM>) between the first cover (<NUM>) and the second cover (<NUM>),
wherein the gas duct (<NUM>) includes a baffle plate (<NUM>) between the first cover (<NUM>) and a second cover (<NUM>), wherein the baffle plate (<NUM>) is configured to bend the gas discharge path in the gas duct (<NUM>), to reduce the momentum and to lower the temperature to safely discharge the gas to the outside, and
the power supply device (<NUM>, <NUM>) further comprises
a third cover (<NUM>) that is provided on an upper surface of the second cover (<NUM>) and abuts on an upper surface of the second cover (<NUM>), third cover (<NUM>) being made of metal.