JP5120631B2 - Battery pack and power supply system - Google Patents

Description

  The present invention relates to an assembled battery constructed using a plurality of unit cells and a power supply system including the assembled battery.

Constructed by using multiple storage cells such as lithium-ion batteries, nickel-metal hydride batteries, and other secondary batteries or capacitors that charge and discharge when lithium ions move between the positive and negative electrodes. The assembled battery has become increasingly important as a power source for mounting on a vehicle or a power source for a personal computer or a portable terminal. In particular, an assembled battery in which a plurality of lithium ion batteries that are lightweight and have a high energy density are connected in series as single cells is expected to be preferably used as a high-output power source for mounting on vehicles. For example, Patent Document 1 is cited as a prior art document relating to a lithium ion battery (single cell).
JP 2002-231316 A

  By the way, some uses of the lithium ion battery are assumed to be used in a mode in which high rate discharge (rapid discharge) is performed. As a single battery for constructing an assembled battery used for a power source of a vehicle (for example, an assembled battery mounted on a hybrid vehicle using a battery and another power source having a different operating principle such as an internal combustion engine as a power source) The lithium ion battery is a typical example of a lithium ion battery in which such a usage mode is assumed. However, even though conventional lithium ion batteries show relatively high durability for use at low rates (charging / discharging), performance degradation (increase in internal resistance) when used at high rates Etc.). When such performance deterioration occurs in any of the single cells constituting the assembled battery, the performance of the assembled battery as a whole may be significantly reduced.

  Patent Document 1 describes a technique for suppressing an increase in internal resistance due to the progress of a charge / discharge cycle by using a negative electrode having a composition obtained by adding a conductive material to a carbon material having a specific structure and an electrolyte solution having a predetermined concentration. However, even with such a technique, it has not been possible to sufficiently improve the durability against a charge / discharge pattern that repeats high-rate discharge (for example, rapid discharge at a level required in a lithium ion battery for a vehicle power source).

  Accordingly, an object of the present invention is to provide an assembled battery (typically, an assembled battery constructed by using a lithium ion battery as a single battery) that exhibits good durability even when used at a high rate. Another object of the present invention is to provide a power supply system including an assembled battery that can better maintain the performance of the assembled battery even when used at a high rate.

  When the present inventor performs high-rate charge / discharge on a unit cell (for example, a lithium ion battery) in which a positive electrode terminal and a negative electrode terminal are respectively connected to one end and the other end of the electrode body, the positive electrode terminal connection side end portion And since the temperature rise of those center parts was large compared with the temperature rise of the negative electrode terminal connection side edge part, it discovered that a temperature difference (temperature deviation) arises between this center part and the said both ends. When such a temperature distribution exists, the battery reaction (current) concentrates at a relatively high temperature location and the deterioration of the location easily proceeds. As a result, the entire single cell (and thus the single cell is included as a component). The performance of the entire assembled battery) may deteriorate faster than usual. In addition, since the amount of heat generation increases at locations where battery reactions concentrate, the temperature difference once generated tends to fall into a vicious circle. Therefore, the present inventor has found a configuration that can eliminate or alleviate such a temperature difference and has completed the present invention.

  The assembled battery provided by the present invention includes a plurality of chargeable / dischargeable single cells (typically lithium ion batteries) and a cooling mechanism that dissipates heat generated from the single cells to the outside. In the unit cell, an electrode body in a form in which sheet-like electrodes are superposed (typically, a wound electrode body in a form in which the superposed sheet-like electrodes are wound in the longitudinal direction) is placed in a container together with an electrolyte. It has a housed configuration. Positive and negative electrode terminals are connected to one end and the other end of the electrode body, respectively. And the said cooling mechanism is comprised so that the cooling efficiency of those center parts may become high compared with the positive electrode terminal connection side edge part and negative electrode terminal connection side edge part (namely, both ends) of the said electrode body.

  According to the assembled battery having such a configuration, the temperature of the central part tends to rise greatly compared to both ends of the unit cell due to the high rate use, and the central part is cooled more efficiently than the both ends. It is possible to eliminate or alleviate an event in which a temperature difference occurs between both ends. Thereby, it is possible to prevent the bias of the battery reaction in the unit cell and the promotion of partial deterioration (for example, increase in internal resistance) due to this. As a result, the durability against high rate use can be improved as a whole assembled battery.

  In the present specification, the “single cell” is a term indicating individual power storage elements constituting the assembled battery, and includes batteries and capacitors of various compositions unless specifically limited. The “secondary battery” refers to a battery that can be repeatedly charged, and includes so-called storage batteries such as lithium ion batteries and nickel metal hydride batteries. The electric storage element constituting the lithium ion battery is a typical example included in the “unit cell” referred to herein, and the lithium ion battery module including a plurality of such unit cells is disclosed in the “assembled battery” Is a typical example. In the technology disclosed herein, a predetermined number of single cells (for example, lithium ion batteries) having a flat outer shape are arranged in a direction in which the flat surfaces are stacked (stacking direction), and electrode terminals of the single cells are arranged in series. Or it can apply especially preferably to the assembled battery formed by connecting in parallel.

  As a preferable application object of the technology disclosed herein, the unit cell includes a flat rectangular container, and the electrode body (typically a wound electrode body) includes the positive terminal connecting side end and the electrode body. Negative electrode terminal connection side ends (both ends) are accommodated in the container so as to be positioned at one end and the other end in the lateral direction of the container, respectively, and the plurality of unit cells are arranged in the stacking direction. An assembled battery having the above configuration is exemplified. The cooling mechanism includes a refrigerant passage (a passage through which a fluid (typically air) that can function as a refrigerant can be circulated) formed between the flat surfaces of the adjacent unit cells. The refrigerant passage is typically formed so as to face at least one flat surface of adjacent unit cells (so that at least a part of the refrigerant passage is partitioned by the flat surface).

  In a preferable aspect of the assembled battery having such a configuration, the assembled battery includes a spacer plate disposed between flat surfaces of the unit cells adjacent in the arrangement in the stacking direction. The refrigerant passage is formed facing the plate (typically, between the flat surface of at least one unit cell sandwiching the plate and the plate). And as for the said spacer plate, those center parts are comprised with the material with higher heat conductivity compared with the both ends (one end part and other end part) of the said horizontal direction. According to such a configuration, the heat at the central portion in the lateral direction of the unit cell is compared with both end portions through the high thermal conductivity portion provided at the center portion of the plate (that is, the portion with higher cooling efficiency than both end portions). Can be dissipated more efficiently. Thereby, the phenomenon which a temperature difference produces between a center part and both ends can be eliminated or eased.

  The spacer plate may have, for example, a configuration having a plurality of parallel grooves (lateral grooves) formed on at least one surface so as to extend from one end to the other end in the horizontal direction. Also, a plurality of parallel grooves formed on at least one surface so as to extend from the upper end in the vertical direction to the lower end (a planar direction that intersects (typically orthogonal) the horizontal direction and is not limited to the vertical direction). It may be a spacer plate having a structure having (vertical groove). Or the spacer plate of the structure by which the said horizontal groove was formed in one surface, and the said vertical groove was formed in the other surface may be sufficient.

  In this way, according to the spacer plate in which the central portion in the horizontal direction is made of a material having a higher thermal conductivity than both ends, for example, the structure of the plate (the groove forming the refrigerant passage is formed at the central portion in the horizontal direction and both ends. Although the shape, arrangement, etc.) are generally the same, the cooling efficiency of the central portion can be increased compared to the both end portions. Therefore, the effect of the present invention (that is, the effect of improving the durability of the assembled battery by relaxing the temperature difference between the central portion and both end portions of the unit cell) can be realized by the spacer plate having a simpler structure. Further, in the spacer plate in which the central portion in the horizontal direction is made of a material having higher thermal conductivity than both ends, the ratio of the area where the flat surface is exposed to the refrigerant passage in the central portion compared to the both ends in the horizontal direction is The structure of the plate may be different between the center portion and both end portions so as to be higher. According to the spacer plate having such a structure, the cooling efficiency of the central portion with respect to both end portions can be further increased, and thereby, the temperature difference between the central portion and both end portions can be more relaxed or eliminated.

  In another preferable aspect of the assembled battery having the above-described configuration, the cooling mechanism has a ratio of an area where the flat surface is exposed to the refrigerant passage at the central portion as compared with both lateral ends of the flat surface. It is configured to be high. According to such a configuration, heat generated in the unit cell can be dissipated more efficiently than the both end units through the flat surface exposed in the refrigerant passage at the central portion in the lateral direction of the unit cell. Thereby, the phenomenon which a temperature difference produces between a center part and both ends can be eliminated or eased.

  The assembled battery includes a spacer plate disposed between the flat surfaces of the unit cells, and faces the plate (typically, the flat surface of at least one unit cell sandwiching the plate and the plate). The refrigerant passage may be formed between the refrigerant passages. Alternatively, for example, a plurality of bowl-shaped convex portions are provided substantially parallel to the container itself constituting the flat surface, and the flat surface having such convex portions is pressed against the flat surface of the adjacent unit cell. The refrigerant | coolant channel | path which faced both flat surfaces (namely, divided by the container outer surface of the adjacent single cell) may be formed in between.

  Any of the assembled batteries disclosed herein, which includes the spacer plate (the central part in the lateral direction may be a plate made of a material having a higher thermal conductivity than both ends). In addition, it is possible to form a groove that defines a refrigerant passage extending from one end to the other end in the horizontal direction of the plate and extends from one end to the other end in the horizontal direction. In a preferred embodiment, a longitudinal groove extending across the transverse groove is formed at a central portion in the transverse direction of the spacer plate, the groove defining a refrigerant passage extending from the upper end to the lower end in the longitudinal direction of the plate. Yes. According to this configuration, the whole cell is cooled by circulating the refrigerant in the horizontal direction of the flat surface through the horizontal groove, and further in the vertical direction of the flat surface through the vertical groove in the central portion of the cell. Therefore, the central portion can be cooled more efficiently than both end portions. Thereby, the phenomenon which a temperature difference produces between a center part and both ends can be eliminated or eased.

  Any of the assembled batteries disclosed herein, which includes the spacer plate (the central part in the lateral direction may be a plate made of a material having a higher thermal conductivity than both ends). Further, a groove that divides the refrigerant passage from the upper end to the lower end in the vertical direction of the plate and extends from the upper end to the lower end in the vertical direction has one end portion and the other end portion in the horizontal direction of the container. And an embodiment formed in each of the central portions. In a preferred aspect, the longitudinal grooves are formed with a larger opening width and / or a smaller pitch at the central portion than at both lateral end portions. According to such a configuration, both ends and the center of the unit cell can be cooled by circulating the refrigerant through the vertical groove, and more refrigerant per flat area in the center than the both ends. Therefore, the central portion can be cooled more efficiently than both end portions. Thereby, the phenomenon which a temperature difference produces between a center part and both ends can be eliminated or eased.

  An opening that penetrates through the plate in the thickness direction may be formed at a central portion in the lateral direction of the spacer plate. According to the spacer plate having such a configuration, the heat of the central portion can be dissipated using the opening, and therefore the central portion can be cooled more efficiently than both end portions. Thereby, the phenomenon which a temperature difference produces between a center part and both ends can be eliminated or eased.

  In this way, the spacer plate having a different structure at the center and both ends in the lateral direction may be formed of the same material at the center and both ends (typically, the entire plate), or For example, the central portion may be formed of a material having a higher thermal conductivity than both ends. A spacer plate formed entirely of the same quality material is preferable because the plate can be easily manufactured. In addition, according to the spacer plate formed of a material having a higher thermal conductivity than the both end portions, the central portion can further increase the cooling efficiency of the center portion with respect to the both end portions. The temperature difference can be alleviated or eliminated better.

  Since any of the assembled batteries disclosed herein can exhibit good durability for use at a high rate as described above, an assembled battery mounted on a vehicle (for example, a motor of a vehicle such as an automobile) (Power source for (motor)) is suitable. Therefore, according to this invention, the vehicle provided with one of the assembled batteries disclosed here is provided.

  According to the present invention, a plurality of chargeable / dischargeable single cells (typically lithium ion batteries), an assembled battery including a cooling mechanism that dissipates heat generated from the single batteries to the outside, and operation of the cooling mechanism And a cooling control means for controlling the power supply system. In the unit cell, an electrode body in a form in which sheet-like electrodes are superposed (typically, a wound electrode body in a form in which the superposed sheet-like electrodes are wound in the longitudinal direction) is placed in a container together with an electrolyte. It has a housed configuration. Positive and negative electrode terminals are connected to one end and the other end of the electrode body, respectively. The said cooling mechanism is comprised so that the relative cooling efficiency of the positive electrode terminal connection side edge part of the said electrode body and a negative electrode terminal connection side edge part (both ends) and those center parts can be changed. The cooling control means includes current value detection means for detecting a discharge current value of the assembled battery, and cooling efficiency adjustment means for changing the cooling efficiency according to the detected value, and the detected value is lower than a predetermined value. The operation of the cooling mechanism can be controlled to increase the relative cooling efficiency of the central portion when the temperature is high.

  According to the power supply system having such a configuration, the relative cooling efficiency of the central portion (cooling efficiency with respect to both ends) is higher during high-rate charge / discharge when the temperature difference between the central portion and both ends tends to be larger than during low-rate charge / discharge. Thus, it is possible to change (adjust) the balance of the cooling efficiency between the central portion and both end portions. As a result, the temperature difference in the unit cell can be moderated or eliminated appropriately under both high rate and low rate use conditions.

  The battery pack constituting the power supply system disclosed herein includes a flat rectangular container in which the unit cell is flat, and the electrode body (typically a wound electrode body) is connected to the positive terminal connecting portion side end. And the negative electrode terminal connecting portion side end portions (both end portions) are accommodated in the container so as to be positioned at one end portion and the other end portion in the lateral direction of the container, respectively, and a plurality of the unit cells are stacked. It may be an assembled battery having a configuration arranged in a direction. The cooling mechanism includes a refrigerant passage formed between flat surfaces of adjacent unit cells. Here, the refrigerant passage is formed in the longitudinal direction of the container at each of one end and the other end in the lateral direction of the container and the central part thereof.

  The assembled battery includes a spacer plate disposed between the flat surfaces of the unit cells, and faces the plate (typically, the flat surface of at least one unit cell sandwiching the plate and the plate). The refrigerant passage may be formed between the refrigerant passages. Alternatively, for example, a plurality of bowl-shaped convex portions are provided substantially parallel to the container itself constituting the flat surface, and the flat surface having such convex portions is pressed against the flat surface of the adjacent unit cell. The refrigerant | coolant channel | path which faced both flat surfaces (namely, divided by the container outer surface of the adjacent single cell) may be formed in between.

  In a preferred aspect, the cooling mechanism is a shielding member capable of at least partially shielding at least a part of the refrigerant passage, and the timing of the shielding can be controlled by the cooling control means. Including a shield member. According to the power supply system having such a configuration, the relative cooling efficiency of the central portion is increased at the high rate by changing the degree of the shielding member shielding the refrigerant passage at the central portion and / or both ends between the low rate and the high rate. The balance of cooling efficiency can be changed (adjusted) to be higher. As a result, the temperature difference in the unit cell can be moderated or eliminated appropriately under both high rate and low rate use conditions.

  Since any of the power supply systems disclosed herein can achieve good durability against high-rate use in the assembled battery constituting the system as described above, a power supply system mounted on a vehicle (for example, an automobile or the like) This is suitable as a power supply system for a motor (electric motor) of the vehicle. Therefore, according to this invention, the vehicle provided with one of the power supply systems disclosed here is provided.

  As a preferable application object of the technology disclosed herein, lithium ions that can be used in a charge / discharge cycle including a high-rate discharge of 50 A or more (for example, 50 A to 250 A), or even 100 A or more (for example, 100 A to 200 A). Batteries: Large capacity type with a theoretical capacity of 1 Ah or more (and 3 Ah or more), and used in a charge / discharge cycle including high-rate discharge of 10 C or more (for example, 10 C to 50 C) or 20 C or more (for example, 20 C to 40 C). Examples of the battery pack include a lithium ion battery that is assumed to be a single battery, and a power supply system including the battery pack.

  Moreover, as a preferable application target of the technology disclosed herein, the size when the electrode body is viewed from the side of the winding axis is 5 cm or more in the winding axis direction (lateral direction in FIG. 4) (typically from 5 cm to 5 cm). An assembled battery including a lithium ion battery having a size of 25 cm (for example, 7 cm to 20 cm) as a single battery and a power supply system including the assembled battery are exemplified. Thus, in the lithium ion battery having a relatively long (large) axial length of the electrode body, the temperature difference tends to be large between the axial end portions and the central portion. It is beneficial.

  Further, the technology disclosed herein includes an electrode body in which a positive and negative electrode sheet and a separator are wound in a flat shape, and the electrode body is a size as viewed from the normal direction of the flat surface (the lateral direction of the winding axis). Is 5 cm or more (typically 5 cm to 25 cm, eg 7 cm to 20 cm) in the winding axis direction, and 5 cm or more (typically 5 cm to 25 cm, eg 7 cm) in the height direction (longitudinal direction in FIG. 3). It can be preferably applied to a lithium ion battery that is ˜20 cm). As described above, in the lithium ion battery having a relatively long and large axial length of the electrode body, the temperature difference tends to be large between the axial end portions and the central portion. It is particularly beneficial to apply.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the following drawings, members / parts having the same action are described with the same reference numerals, and overlapping descriptions may be omitted or simplified.

  Note that matters other than matters specifically mentioned in the present specification and necessary for carrying out the present invention (for example, configuration and manufacturing method of positive electrode, negative electrode and separator, manufacturing method of electrode body, assembled battery for vehicle) The mounting method) can be grasped as a design matter of those skilled in the art based on the prior art in the field. The present invention can be carried out based on the contents disclosed in this specification and common technical knowledge in the field.

  The assembled battery according to the present invention can be suitably used as a power source for a motor (electric motor) mounted on a vehicle such as an automobile. Accordingly, as schematically shown in FIG. 18, the present invention provides a vehicle (typically, an automobile equipped with an electric motor such as an automobile, particularly a hybrid automobile, an electric automobile, or a fuel cell automobile) having such an assembled battery 10 as a power source. I will provide a.

  The power supply system according to the present invention can be suitably used as a power supply system for a motor (electric motor) mounted on a vehicle such as an automobile. Therefore, the present invention provides a vehicle (for example, an automobile including the power supply system 2 constructed including the assembled battery 10 as schematically shown in FIG. 18) equipped with such a power supply system.

<Example 1>
The configuration of the assembled battery 10 according to the present embodiment (Example 1) will be described with reference to FIGS. 1 to 5, taking as an example the case where a lithium ion battery is used as the single battery.

  The assembled battery 10 according to the present embodiment includes a plurality of chargeable / dischargeable cells (here, lithium ion batteries) 20. The cell 20 is a predetermined battery constituent material (sheet-like electrode in which the active material of each of the positive and negative electrodes is held on the current collector of each of the positive and negative electrodes, A flat-shaped wound electrode body 80 having a separator or the like is housed in a container 50 having a shape capable of housing the electrode body (here, a flat rectangular parallelepiped shape, that is, a square shape) together with an appropriate liquid electrolyte (electrolyte). It has the structure made. The material which comprises the container 50 can be made into the same thing as what is used with a typical cell, for example, and there is no restriction | limiting in particular. From the viewpoint of heat dissipation of the unit cell 20, a metal (for example, aluminum) container 50 can be preferably used. On the upper surface of the container 50, a positive electrode terminal 60 and a negative electrode terminal 62 that are electrically connected to the positive electrode and the negative electrode of the wound electrode body 80, respectively, are provided. In addition, one positive terminal 60 and the other negative terminal 62 are electrically connected by a connector 64 between adjacent unit cells 20. Thus, the assembled battery 10 of the desired voltage is constructed | assembled by connecting the several cell 20 in series.

  The configuration of the unit cell 20 will be described in more detail with reference to FIGS. 3 and 4.

  As shown in FIG. 4, the electrode body 80 has a long sheet-like positive electrode 82 (hereinafter also referred to as “positive electrode sheet 82”) and a long sheet-like negative electrode, like a wound electrode body of a normal lithium ion battery. 84 (hereinafter also referred to as “negative electrode sheet 84”) together with a total of two long sheet-like separators 86 (hereinafter also referred to as “separator sheets 86”), and wound in the longitudinal direction. It can be produced by squashing the rotator from the lateral direction (transverse to the winding axis).

  Here, the positive electrode sheet 82 and the negative electrode sheet 84 are wound in a state where the positions are slightly shifted in the width direction of these long sheets and are overlapped. As a result, as shown in FIG. 4, one end in the width direction of the positive electrode sheet 82 has a wound core portion 81 (that is, the positive electrode sheet 82) at one end and the other end in the winding axis direction of the wound electrode body 80. Positive electrode active material layer forming portion, negative electrode active material layer forming portion of negative electrode sheet 84 and separator sheet 86 are tightly wound), and a positive electrode protruding portion (positive electrode terminal connecting portion) 82A protruding outward. A negative electrode protruding portion (negative electrode terminal connecting portion) 84A in which one end in the width direction of the negative electrode sheet 84 protrudes outward from the wound core portion 81 is formed. A positive electrode lead terminal 82B and a negative electrode lead terminal 84B are attached to the positive electrode protruding portion (ie, the non-formed portion of the positive electrode active material layer) 82A and the negative electrode protruding portion (ie, the non-formed portion of the negative electrode active material layer) 84A, respectively. Lead terminals 82B and 84B are electrically connected to the positive terminal 60 and the negative terminal 62, respectively.

The material and the member constituting the wound electrode body 80 may be the same as those of a conventional lithium ion battery, and are not particularly limited. For example, the positive electrode sheet 82 can be formed by applying a positive electrode active material layer for a lithium ion battery on a long positive electrode current collector. For the positive electrode current collector, an aluminum foil (this embodiment) or other metal foil suitable for the positive electrode can be suitably used. As the positive electrode active material, one type or two or more types of materials conventionally used in lithium ion batteries can be used without any particular limitation. As a preferred example, a lithium-nickel composite oxide (an oxide containing lithium and nickel as constituent metal elements), a part of nickel site (typically less than half) is other metal elements such as cobalt and aluminum. It is meant to include substituted ones, typically LiNiO ₂ ), lithium cobalt complex oxide (typically LiCoO ₂ ), lithium manganese complex oxide (typically LiMn ₂ O ₄ ). And lithium transition metal composite oxides. For example, a long aluminum foil having a thickness of about 5 μm to 20 μm (for example, 15 μm) is used as a current collector, and a positive electrode active material layer mainly composed of a lithium nickel-based composite oxide is formed on a predetermined region of the surface by a conventional method. A suitable positive electrode sheet 82 is obtained by forming.

  On the other hand, the negative electrode sheet 84 can be formed by providing a negative electrode active material layer for a lithium ion battery on a long negative electrode current collector. For the negative electrode current collector, a copper foil (this embodiment) or other metal foil suitable for the negative electrode can be suitably used. As the negative electrode active material, one type or two or more types of materials conventionally used in lithium ion batteries can be used without any particular limitation. Preferable examples include carbon-based materials such as graphite carbon and amorphous carbon, lithium transition metal oxides (such as lithium titanium oxide), and lithium transition metal nitrides. For example, a long copper foil having a thickness of about 5 μm to 20 μm (for example, 10 μm) is used, and a negative electrode active material layer mainly composed of a carbon-based material (typically graphite) is formed on a predetermined region of the surface by a conventional method. By forming it, a suitable negative electrode sheet 84 is obtained.

  Moreover, as a suitable separator sheet 86 used between the positive / negative electrode sheets 82 and 84, what was comprised by the synthetic resin (for example, polyolefin, such as polyethylene and a polypropylene) is illustrated. For example, a porous separator sheet made of polyolefin resin and having a thickness of about 5 μm to 30 μm (for example, 25 μm) can be suitably used.

The obtained flat wound electrode body 80 is placed in the container 50 so that the winding shaft lies sideways as shown in FIG. 3 (that is, the portion of the electrode body 80 on the positive electrode protruding portion 82A side and the negative electrode protruding) By accommodating a portion 84A on the side of the container 50 so that the portion is located at one end and the other end in the lateral direction of the container 50, and injecting and sealing a suitable nonaqueous electrolyte (not shown) A single battery 20 is constructed. As the electrolytic solution, for example, an electrolyte containing an appropriate amount of a supporting salt (for example, a lithium salt such as LiPF ₆ ) in a nonaqueous solvent (such as a mixed solvent of diethyl carbonate and ethylene carbonate) is preferable. Can be used.

  In the assembled battery 10 of this embodiment, as shown in FIGS. 1 and 2, a plurality of (here, four are shown) unit cells 20 having the above-described configuration are arranged in a predetermined direction and the arrangement direction. It is restrained in a state where a load is applied. Specifically, the plurality of unit cells 20 are arranged so as to be inverted one by one so that the positive terminals 60 and the negative terminals 62 are alternately arranged, and the flat surfaces 52 ( The wide surface of the container 50, that is, the surface corresponding to the flat surface of the wound electrode body 80 accommodated in the container 50 is arranged in a direction (stacking direction) facing each other.

A restraining member that restrains the plurality of unit cells 20 together is provided around the arranged unit cells 20. That is, a pair of restraining plates 70A and 70B are arranged on the outer side of the unit cell 20 located on the outermost side in the unit cell arrangement direction. Further, a fastening beam member 72 is attached so as to bridge the pair of restraining plates 70A and 70B. Then, by tightening and fixing the end portion of the beam member 72 to the restraining plate 70A with the screw 74, the unit cell 20 is applied with a predetermined load in the arrangement direction (for example, the surface pressure received by the flat surface 52 is reduced). It can be restrained so that it becomes about 2 × 10 ^{6 to} 5 × 10 ⁶ Pa. A restraining load (surface pressure) in the tightening direction (that is, the arrangement direction) is applied to the flat surface 52 of each unit cell 20 at a level corresponding to the tightening condition of the beam material 72.

  Here, the spacer plate 140 is disposed in at least one place (in the illustrated example, between adjacent unit cells 20 and both outsides in the unit cell arrangement direction) of the gaps between the arranged unit cells 20. Thereby, a refrigerant passage 146 as a cooling mechanism of the assembled battery 10 is formed. As shown in FIGS. 3 and 5, the spacer plate 140 of the present embodiment has a rectangular plate shape that is almost the same size as the flat surface 52 of the container 50 as a whole, and one surface thereof is linear in the lateral direction. A concave-convex shape in which a hook-shaped convex portion 142 and a groove-shaped concave portion 144 are alternately formed (that is, a comb-shaped concave-convex shape as viewed from the side as shown in FIG. 3). Although not particularly limited, the width of the convex portion 42 is, for example, about 0.2 cm, the width of the concave portion 44 formed in a straight line is about 0.8 cm, and the depth of the concave portion 44 (that is, the height of the convex portion 42). ) Can be about 0.2 cm. On the other hand, the other surface (back surface) of the plate 140 has a flat shape.

  When the plate 140 having such a shape is constrained together with the unit cell 20 as shown in FIG. 2, as shown in FIG. 3, the flat surface of the unit cell 20 adjacent to the surface side of the plate 140 (the side on which the concavo-convex shape is formed). 52, while the tip of the convex portion 142 is in close contact, the concave portion (lateral groove) 144 formed between the convex portions 142 does not come into contact with the flat surface 52. A gap 146 facing the flat surface 52 of the unit cell 20 and the plate 140 (groove 144) is formed. By causing a cooling medium (typically air) to flow through the gap 146 (that is, using the gap 146 as a refrigerant passage), heat generated in the unit cell 20 can be dissipated. The entire back surface of the plate 140 is in close contact with the flat surface 52 of the other unit cell 20.

  Here, as shown in FIG. 5, the plate 140 of the present embodiment includes one end portion (positive terminal connection side end portion) 140 </ b> A and the other end portion (negative electrode terminal connection side end portion) 140 </ b> B in the lateral direction, and the center thereof. The part 140C is formed using a different constituent material. The uneven shape (convex portion 142 and concave portion 144) on the surface is formed so as to extend from one end to the other end in the lateral direction of the plate 140 across these different portions of the material. These constituent materials are selected in such a combination that the thermal conductivity of the constituent material of the central portion 140C is higher than the constituent materials of the both end portions 140A and 140B. For example, a resin material (for example, light and hard polypropylene or other synthetic resin material) is used as a constituent material for both ends 140A and 140B, and a metal material (for example, aluminum that is lightweight and has high thermal conductivity) or the like as a constituent material for the central portion 140C The metal material) can be preferably used. Moreover, the combination of the constituent material of both ends 140A and 140B and the constituent material of the center part 140C may be resin materials or metal materials having different thermal conductivities. Alternatively, for example, a resin material such as polypropylene is used as a constituent material of both end portions 140A and 140B, and a composite material of the resin material and metal (for example, a resin mixed with metal particles, metal fibers, etc.) as a constituent material of the central portion 140C Material) may be used.

  The widths (lateral lengths) of the one end portion 140A, the other end portion 140B, and the central portion 140C are not particularly limited, and the configuration of the unit cell and the assembled battery, the usage mode of the assembled battery, and the target degree of relaxation of the temperature difference Etc. can be set as appropriate. In general, it is preferable that the one end portion 140A and the other end portion 140B have the same width from the viewpoint of ease of manufacture and the like. For example, a configuration in which the ratio of the width of one end portion: the central portion: the other end portion is about 1: 2: 1 to 2: 1: 2 can be preferably employed. In the present embodiment, the ratio is approximately 1: 1: 1.

  Here, there is a relationship represented by the following formula: J = −λ (gradT); between the heat flow density (the amount of heat flowing through the unit area per unit time) J and the thermal conductivity λ (gradT in the formula) Indicates a temperature gradient). Therefore, when the thermal conductivity λ of the material constituting the heat radiating member (here, the spacer plate 140) is doubled, for example, the amount of heat radiated by the member is also increased by the same factor (here, doubled). By utilizing this fact, according to the plate 140 having the above-described configuration, the central portion of the unit cell 20 is closer to the end portions 140A and 140B (corresponding to the axial end portions of the wound electrode body 80). In a portion close to 140C (corresponding to the central portion in the axial direction of the electrode body 80), heat is radiated more efficiently through the central portion 140C made of a material having higher thermal conductivity (that is, the central portion). The portion close to 140C can be cooled more efficiently). In this embodiment, aluminum (thermal conductivity around room temperature is about 236 W / m · K) as the constituent material of the central portion 140C, and polypropylene resin (thermal conductivity of 0.17 to 0.19 W) as the constituent material of both end portions 140A and 140B. / M · K grade). In this combination, the thermal conductivity of the central portion 140C is 1000 times or more that of both end portions 140A and B. Thereby, compared with the both ends of the wound electrode body 80, the cooling efficiency of the center part can be made higher.

  In order to confirm the significance of adopting the above configuration, a lithium ion battery having the same configuration as the unit cell 20 in the above embodiment was manufactured, and a temperature difference generated between both ends and the center by high rate charge / discharge was measured. .

  That is, lithium nickelate powder (positive electrode active material), acetylene black (conductive material), and carboxymethyl cellulose (CMC) are mixed with ion-exchanged water so that the mass ratio of these materials is 87: 10: 3. A material composition (positive electrode active material composition) was prepared. A long aluminum foil is used as the positive electrode current collector, and one end of the current collector is left in the width direction (positive electrode protruding portion 82A). It was applied in a band and dried. After drying, the whole including the positive electrode current collector and the active material layers provided on both sides thereof was pressed to obtain a positive electrode sheet 82.

  Further, natural graphite (powder), styrene butadiene rubber (SBR), and CMC are mixed with ion-exchanged water so that the mass ratio of these materials becomes 98: 1: 1. Prepared). A long copper foil is used as the negative electrode current collector, and one end in the width direction is left out of the current collector (negative electrode protruding portion 84A). It was applied in a band and dried. After drying, the whole including the negative electrode current collector and the active material layers provided on both sides thereof was pressed to obtain a negative electrode sheet 84.

  As the separator sheet 86, two porous polyethylene sheets were used. The separator sheet 86 and the positive electrode sheet 32 and the negative electrode sheet 34 obtained above are laminated so that the protruding portions 32A and 34A protrude from both sides in the width direction, and wound in the longitudinal direction. Was crushed from the side to obtain a flat wound electrode body 80.

  The positive electrode sheet 82 constituting the positive electrode protruding portion 82A of the electrode body 80 is gathered in the radial direction (normal direction with respect to the flat surface) and welded to the aluminum positive electrode lead terminal 82B to form the negative electrode protruding portion 84A. The negative electrode lead terminals 84B made of copper were welded together by gathering 84 in the radial direction. These lead terminals 82B and 84B were connected to the positive terminal 60 and the negative terminal 62 of the container 50, respectively.

As the container 50, an aluminum container having a flat box-shaped outer shape having a height (vertical length) of 9.2 cm, a width (horizontal length) of 11 cm, and a thickness of 1.35 cm was used. As shown in FIG. 2, a wound electrode body 80 is accommodated inside the container 50. In addition, in order to make it possible to measure the temperature of each part from the outside, one end of the container 50 (the end on the positive electrode terminal side), the other end (the end on the negative electrode terminal side), Thermocouples were set in the center of each. After injecting an electrolytic solution containing lithium hexafluorophosphate (LiPF ₆ ) as a supporting salt in a mixed solvent of EC, DMC and EMC into the container 50 at a concentration of about 1 mol / liter, the container 50 is Sealed. Thereafter, an initial charge / discharge treatment (conditioning) was performed by a conventional method to obtain a lithium ion battery 20 having a theoretical capacity of 5 Ah.

  A charge / discharge pattern including a high rate discharge for 10 seconds at 150 A (corresponding to a discharge time rate of 30 C) is applied to the lithium ion battery 20 obtained above, and the temperature change of each part due to this is detected by the thermocouple. I grasped it from the value. More specifically, by applying the following charge / discharge patterns (1) to (4) in a room temperature (about 25 ° C.) environment, and comparing the temperature of each part before and after that, each part by the above charge / discharge pattern The temperature rise width of was determined.

[Charge / discharge pattern]
(1) Discharge at 150 A for 10 seconds.

  (2) Pause for 5 seconds.

  (3) CC-CV charge at 40 A for 120 seconds (constant voltage charge until constant charge is 120 seconds after constant current charge to 3.72 V at 40 A).

  (4) Pause for 5 seconds.

  As a result, before and after the charge / discharge pattern (one cycle), the temperature upper layer width at both end portions of the battery was 1.2 ° C., whereas the temperature increase width at the center portion was 2.2 ° C. That is, in the high-rate (rapid) charge / discharge pattern as described above, a clear temperature difference was generated between the both ends and the center of the battery even after only one high-rate discharge for 10 seconds. If the charge / discharge pattern continues further, the battery reaction (current) concentrates on the relatively hot spot, and as a result, more heat is generated at the hot spot, increasing the temperature difference once generated. Will be. For example, the temperature difference between the central portion and both end portions after the charge / discharge pattern was continuously repeated was increased to 7 ° C.

  FIG. 6 shows a lateral temperature distribution image of the unit cell 20 in the case where the assembled battery 10 similar to the above embodiment is constructed using the unit cell that generates the temperature distribution as described above by high-rate charge / discharge. The two-dot chain line in the figure has the same outer shape as the spacer plate 140 of the above embodiment as a spacer plate constituting the assembled battery 10, but, unlike the above embodiment, not only both ends 140A and B but the center. Part 140C also schematically shows a temperature distribution when a spacer plate made of polypropylene resin (that is, made entirely of a single material) is used. Thus, according to the spacer plate having the same cross-sectional shape and thermal conductivity (and hence cooling efficiency) in each part of the battery in the lateral direction, a temperature difference is generated between the both ends and the center of the unit cell 20.

  The alternate long and short dash line in FIG. 6 has the same external shape as the spacer plate 140 of the above embodiment, but unlike the above embodiment, not only the central portion 140C but also the both end portions 140A and B are made of aluminum. The temperature distribution when used is schematically shown. Thus, according to the plate made entirely of aluminum, although the cooling efficiency in each part of the battery in the lateral direction is higher than the plate made entirely of polypropylene resin, the cross-sectional shape and thermal conductivity of the plate in each part in the lateral direction are increased. Since they are the same, there is still a temperature difference between the both ends and the center of the unit cell 20.

  On the other hand, in the spacer plate 140 of this embodiment, both end portions 140A and 140B are made of polypropylene resin and only the central portion 140C is made of aluminum having high thermal conductivity. As shown, the temperature of the central portion can be reduced intensively (greater than both ends) compared to the case where a spacer plate made entirely of polypropylene resin is used (two-dot chain line) (downward in FIG. 6) Arrow). Thereby, the temperature difference between the center portion and both end portions can be relaxed (temperature distribution can be made smooth).

<Example 2>
The assembled battery according to the present embodiment is an example in which the outer shape of the spacer plate is different from the assembled battery according to Example 1 described above. That is, in this embodiment, instead of the spacer plate 140 having the shape shown in FIG. 5, as shown in FIG. 7, it extends linearly in the vertical direction and extends from one end (upper end) to the other end (lower end) in the vertical direction. A spacer plate 240 in which convex portions 243 and concave portions (vertical grooves) 245 are alternately formed in parallel is used. The configuration of other parts is the same as that of the assembled battery 10 according to Example 1. That is, the plate 240 of the present embodiment is similar to the spacer plate 140 of Example 1 in that the central portion 240C has a higher thermal conductivity (for example, a material having higher thermal conductivity than the constituent material (for example, polypropylene resin) of both end portions 240A and 240B, for example. Aluminum).

  When the spacer plate 240 having such a configuration is disposed between the adjacent single cells 20, the vertical direction is provided between the concave portion (vertical groove) 245 of the plate 240 and the flat surface 52 of the container 50 adjacent to the surface side of the plate 240. A refrigerant passage 247 extending from the upper end to the lower end is defined. Then, compared to the refrigerant passage 247 formed on both ends 240A and 240B of the plate 240 (facing both ends in the lateral direction of the container 50), both ends in the lateral direction of the container 50 are formed in the central portion 240C. According to the refrigerant passage 247 facing (), more heat can be dissipated (that is, the portion in close contact with the central portion 140C can be cooled more efficiently). Thereby, the temperature difference between both end portions and the central portion can be relaxed or eliminated.

<Example 3>
The assembled battery according to the present embodiment is another example in which the outer shape of the spacer plate is different from the assembled battery according to Example 1 described above. That is, as shown in FIG. 8, the spacer plate 340 of the present embodiment has a cut 341 in the wall surface (convex portion 142) separating adjacent concave portions (lateral grooves) 144 in the central portion in the horizontal direction of the spacer plate 140 shown in FIG. 5. Is provided. As a result, a single vertical groove 345 that intersects the horizontal groove 144 and extends in the vertical direction is formed. The horizontal groove 144 and the vertical groove 345 communicate with each other at their intersection. The configuration of other parts is the same as that of the assembled battery 10 according to Example 1. That is, the plate 340 of the present embodiment is similar to the spacer plate 140 of Example 1 in that the central portion 340C has a material with higher thermal conductivity (for example, polypropylene resin) than the constituent material (for example, polypropylene resin) of both ends 340A and 340B (for example, Aluminum).

  When the spacer plate 340 having such a configuration is arranged between the adjacent single cells 20, a lateral direction between the concave portion (lateral groove) 144 of the plate 340 and the flat surface 52 of the container 50 adjacent to the surface side of the plate 340 is provided. A refrigerant passage 146 extending from one end to the other end is defined. Further, a refrigerant passage 347 extending from the upper end in the vertical direction to the other end is formed between the vertical groove 345 and the flat surface 52 in the central portion of the container 50. Accordingly, the flat surface 52 is exposed to the refrigerant passages 146 and 347 by providing the refrigerant passage 347 (vertical groove 345) that cuts through the central portion in the central portion as compared to both ends of the flat surface 52. The area ratio is high. According to the present embodiment, the central portion 340C of the plate 340 is made of a material having high thermal conductivity, so that the central portion can be cooled with high efficiency only by the refrigerant passage 146 through which the refrigerant flows in the lateral direction (Example 1). In addition, the cooling passage in the vertical direction is formed in the central portion 340C so that the cooling efficiency in the central portion of the battery can be further increased.

<Example 4>
The assembled battery according to the present embodiment is another example in which the outer shape of the spacer plate is different from the assembled battery according to Example 1 described above. That is, as shown in FIG. 9, the spacer plate 440 of the present embodiment has a rectangular opening 448 penetrating through the plate 440 in the thickness direction in the central portion 440C in the horizontal direction. Is provided. The convex portion 142 is interrupted at a portion crossing the opening 448. The configuration of other parts is the same as that of the assembled battery 10 according to Example 1. That is, the plate 440 of the present embodiment is similar to the spacer plate 140 of Example 1 in that the central portion 440C has a higher thermal conductivity (for example, a material having higher thermal conductivity than the constituent material (for example, polypropylene resin) of the both ends 440A and 440B, for example). Aluminum).

  When the spacer plate 440 having such a configuration is disposed between the adjacent single cells 20, a lateral direction is provided between the concave portion (lateral groove) 144 of the plate 440 and the flat surface 52 of the container 50 adjacent to the surface side of the plate 440. A refrigerant passage 146 extending from one end to the other end is defined. In the central portion in the horizontal direction, the flat surface 52 of the container 50 adjacent to the back surface side (flat side) of the plate 440 is exposed to the refrigerant passage 146 through the opening 448 (therefore, using heat radiation from the exposed surface). The central part of the container 50 adjacent to the back surface side can be cooled more efficiently than both ends.) In the opening 448, the convex part 142 (the part in close contact with the flat surface 52 adjacent to the surface side of the plate 440). ) Is interrupted, the ratio of the area where the flat surface 52 is exposed to the refrigerant passage 146 is higher at the center than at both ends. According to this embodiment, in addition to the central portion 440C of the plate 440 being made of a material having high thermal conductivity, the central portion of the flat surface is exposed to the refrigerant passage 146 more than the both end portions, whereby the battery The cooling efficiency at the center can be further increased.

<Example 5>
The assembled battery according to the present embodiment is another example in which the outer shape of the spacer plate is different from the assembled battery according to Example 1 described above. That is, as shown in FIG. 10, the spacer plate 540 of the present embodiment has a substantially square shape that penetrates the plate 540 in the thickness direction, leaving the upper and lower ends of the central portion 540C slightly in the central portion 540C in the lateral direction. A shaped opening 548 is provided. Further, inside the opening 548, an X-shaped bracing 549 is provided along the square diagonal lines. The thickness of the brace 549 is substantially equal to the thickness of the plate 540 in the groove 144. Although the central portion in the lateral direction of the convex portion 144 is interrupted by the opening 548, a convex portion 542 having the same height as the convex portion 142 is formed at a position on the extension line of the convex portion 144 in the brace 549. ing. The configuration of other parts is the same as that of the assembled battery 10 according to Example 1. That is, the plate 540 of the present embodiment is similar to the spacer plate 140 of Example 1 in that the central portion 540C has a higher thermal conductivity (for example, a material having higher thermal conductivity than the constituent material (for example, polypropylene resin) of the both ends 540A and 540B, for example. Aluminum).

  When the spacer plate 540 having such a configuration is arranged between the adjacent single cells 20, a lateral direction between the concave portion (lateral groove) 144 of the plate 540 and the flat surface 52 of the container 50 adjacent to the surface side of the plate 540. A refrigerant passage 146 extending from one end to the other end is defined. In the central portion in the horizontal direction, the flat surface 52 of the container 50 adjacent to the back surface side of the plate 540 is exposed to the refrigerant passage 146 through the opening 548 (therefore, adjacent to the back surface side using heat radiation from the exposed surface). The central portion of the container 50 to be cooled can be cooled more efficiently than the two end portions.) Further, since the convex portion 142 is interrupted at the opening portion 548, the flat surface 52 is at the central portion compared to the both end portions. The ratio of the area exposed to 146 is high. According to this embodiment, in addition to the central portion 440C of the plate 440 being made of a material having high thermal conductivity, the flat central portion is thus exposed to the refrigerant passage 146 more than both end portions. As a result, the cooling efficiency at the center of the battery can be further increased. Further, as shown in the figure, the coolant passage 146 is also opened (opened) at the upper end and the lower end of the plate 540 because the convex portion 142 is interrupted at the central portion 540C where the opening 548 is formed. In the central portion 540C, the refrigerant can also be circulated in the vertical direction, thereby further increasing the cooling efficiency of the central portion. Further, by providing the bracing 549 inside the opening 548, the strength (shape maintaining property) of the plate 540 is increased, and the portion of the bracing 549 (inside the opening 548) located on the extension line of the convex 142 is projected. By providing the portion 542, a sufficient restraining force can be applied between the flat surfaces 52 of the unit cells 20 in the assembled battery 10 even if the opening 548 has a relatively large area.

<Example 6>
The assembled battery according to the present embodiment is another example in which the outer shape of the spacer plate is different from the assembled battery according to Example 1 described above. As shown in FIG. 11, the spacer plate 640 of the present embodiment is a convex portion that extends linearly in the vertical direction and extends from the upper end to the lower end in the vertical direction, like the spacer plate 240 of Example 2 (see FIG. 7). 243 and recesses (vertical grooves) 245 are alternately formed in parallel. However, in the spacer plate 240, the shape (width) and pitch of the convex portion 243 and the concave portion 245 are uniform in each portion in the horizontal direction, whereas in the plate 640, the central portion 640C is convex compared to the both end portions 640A and 640B. The portion 243 is configured to have a narrow width (therefore, the pitch of the recesses 245 is reduced). The configuration of other parts is the same as that of the assembled battery 10 according to Example 1. That is, the plate 640 of the present embodiment is similar to the spacer plate 140 of Example 1 in that the central portion 640C has a material with higher thermal conductivity (for example, polypropylene resin) than the constituent material (for example, polypropylene resin) of both ends 640A and 640B (for example, Aluminum).

  When the spacer plate 640 having such a configuration is disposed between the adjacent single cells 20, the vertical direction is provided between the concave portion (vertical groove) 245 of the plate 540 and the flat surface 52 of the container 50 adjacent to the surface side of the plate 640. A refrigerant passage 247 extending from the upper end to the lower end is defined. Further, in the central portion 640C compared to the both end portions 640A and 640B of the plate 640, the ratio of the area where the flat surface 52 is exposed to the refrigerant passage 247 is high due to the formation pitch of the concave portions 245 being small. According to the present embodiment, in addition to the central portion 640C of the plate 640 made of a material having high thermal conductivity, the coolant passage 247 is formed at a high density in the central portion 640C, so that the cooling efficiency of the battery central portion is increased. Can be made higher.

  In Examples 3 to 6, the central portion of the spacer plates 340, 440, 540, and 640 has been described with reference to a material having a higher thermal conductivity than both ends. However, these plates 340, 440, 540, and 640 In the spacer plate having the same outer shape, even when the central portion and both end portions of the plate are formed of the same material, in the assembled battery constructed using the plate, compared to the lateral end portions of the unit cell. The central part can be cooled with high efficiency.

<Example 7>
The present embodiment is configured to include an assembled battery configured to be able to change the balance of cooling efficiency between both end portions and the central portion in accordance with the use state of the battery (here, the discharge rate), and the assembled battery. The power supply system.

  As shown in FIG. 12, the assembled battery 1 of this embodiment has the same external shape as the spacer plate 240 of Example 2 shown in FIG. 7, except that one end 740A, the other end 740B, and the center 74C in the horizontal direction. Is provided with a spacer plate 740 made of a single material (for example, polypropylene resin). The configuration of other parts is the same as that of the assembled battery 10 according to Example 1. That is, the spacer plate 740 is formed with convex portions 243 and concave portions (vertical grooves) 245 extending in a straight line in the vertical direction and extending from one end (upper end) to the other end (lower end) in the vertical direction alternately in parallel. A refrigerant passage 247 extending from the upper end to the lower end in the vertical direction is defined between the recess (vertical groove) 245 of the plate 240 and the flat surface 52 of the container 50 adjacent to the surface side of the plate 240. In order to make the drawing easier to see, only three of the single cells 20 are shown in FIG. 12, and the spacer plates and the restraining members disposed on both outsides of the single cell array are omitted.

  In FIG. 12, the surface facing the lower left corresponds to the lower surface of the assembled battery 10, and the lower end of the refrigerant passage 247 is opened here. A plate-like guide member 770 having an opening (slit) 772 at a position corresponding to the lower end opening of the refrigerant passage 247 is attached to the lower surface. On the outer surface of the guide member 770, a guide path 776 that holds the shielding member 780 slidably in the lateral direction is provided along both sides of the member 770 extending in the lateral direction of the plate 740. An opening (slit) 782 is formed in the shielding member 780 at a position that can at least partially overlap the refrigerant passage 247 and the opening 772 corresponding thereto. Further, between the slits 782, there are formed shielding portions 784 that can at least partially shield the refrigerant passages 247 provided at both ends in the lateral direction and the opening portions 772 corresponding thereto.

  The electronic control system 2 includes the assembled battery 10 having the above configuration, and a cooling control means 750 including an ammeter 752 that detects a charge / discharge current of the assembled battery and a battery control unit 760. The electronic control unit 760 is configured as a microprocessor centered on the CPU 762. In addition to the CPU 762, a ROM 764 that stores processing programs, a RAM 766 that temporarily stores data, an input / output port (not shown), and the like. It has. A power source (not shown) is connected to the shielding member 780, and the power source operates by receiving a shielding member position signal from the battery control unit 760, whereby the shielding member 780 is laterally moved with respect to the plate 740 and the guide member 770. The position can be varied.

  An operation example of the power supply system 2 of the present embodiment having such a configuration will be described. In the initial state (state when the battery is not used), as shown in FIG. 13, the opening 772 of the guide member 770 (which coincides with the lower end opening of the refrigerant passage 247) and the opening 782 of the shielding member 780. Between the guide member 770 and the plate 740 and the shielding member 780 with respect to the lateral direction of the battery so that the first and second end portions 740A, 740B and the central portion 740C of the plate 740 are completely overlapped with each other. The positional relationship is set. In other words, the lower end opening of the refrigerant passage 247 at either of the both end portions and the central portion is completely (shielded) via the opening 772 of the guide member 770 and the opening 782 of the shielding member 780. (Not) open to the outside.

  FIG. 17 is a flowchart showing a cooling efficiency balance adjustment routine executed by CPU 762 of battery control unit 760. This routine is stored in the ROM 764 and is repeatedly executed by the CPU 762 every predetermined time (for example, every several milliseconds). When this routine is started, the CPU 762 first determines whether the shielding member position flag F is 0 or 1 (step S100). This shielding member position flag F is set to 0 when the shielding member 780 is at the position (reference position) shown in FIG. 13 with respect to the guide member 770 and the plate 740, and the shielding member 780 is shifted to the left from this state. (See the white arrow in FIG. 13) This flag is set to 1 when it is at the position (high-rate position) shown in FIG.

  If the shielding member position flag F is 0 in step S100, the ammeter then determines whether the charge / discharge rate (typically, the discharge rate) corresponds to a high rate of a predetermined value or higher (eg, 100 A or higher) at the present time. A determination is made based on the detection value of 752 (step S110). If it is not a high rate, this routine is terminated as it is. On the other hand, if it is determined that high rate charge / discharge is being performed, the shielding member 780 is moved from the reference position shown in FIG. 13 to the high rate position shown in FIG. 14 (step S120), and the shielding member position flag F is set. 1 is set (step S130), and this routine is terminated.

  Even when the shielding member position flag F is 1 in step S100, subsequently, whether or not the current charge / discharge rate (typically, the discharge rate) corresponds to a high rate equal to or higher than a predetermined value (for example, 100 A or higher) (that is, Whether or not the high rate state has continued since the previous routine execution is determined based on the detection value of the ammeter 752 (step S140). If it is determined that high-rate charging / discharging is being performed, this routine is terminated. On the other hand, when it is determined that it is not the high rate (that is, when the high rate state is stopped), the shielding member 780 is moved from the high rate position shown in FIG. 14 to the reference position shown in FIG. 13 (step S150), and the shielding is performed. The member position flag F is set to 0 (step S160), and this routine is finished.

  In the state where the shielding member 780 is at the position shown in FIG. 14, the refrigerant passage 247 formed in the central portion 740C of the plate 740 is completely opened to the outside as in the state shown in FIG. The refrigerant passages 247 formed in the both end portions 740A and B are partially shielded by the shielding portions 784 formed in the both end portions 780A and B of the shielding member 780. In other words, in the state shown in FIG. 14 as compared with the state shown in FIG. 13, the amount of the refrigerant C flowing through the refrigerant passage 247 formed in the both end portions 740A and B is reduced. As a result, in the state shown in FIG. 14, the relative cooling efficiency of the central portion with respect to both end portions is higher than in the state shown in FIG. Thus, by moving (sliding) the shielding member 780 between the reference position (FIG. 13) and the high-rate position (FIG. 14), the cooling efficiency balance between the both ends and the center can be varied. Then, by executing the above routine, the shielding member 780 can be moved to the position shown in FIG. 14 only at the high rate, and returned to the reference position when the high rate state stops. As a result, the temperature difference in the unit cell can be moderated or eliminated appropriately under both high rate and low rate use conditions. In addition, since the position of the shielding member 780 is controlled based on the charge / discharge rate, for example, the problem can be dealt with more quickly than in the method of controlling the position of the shielding member 780 based on the temperature difference between the both ends and the center. Is possible.

  In the above description, the example of increasing the relative cooling efficiency of the central portion by partially shielding the refrigerant passages at both ends only at the high rate has been described. However, as a modification, for example, only at the high rate, The relative cooling efficiency of the central portion may be increased by releasing the partial shielding. For example, as shown in FIGS. 15 and 16, instead of the spacer plate 740 shown in FIGS. 12 to 14, similarly, a coolant passage 247 penetrating in the vertical direction is formed, but the central portion 840 </ b> C as compared with both end portions 840 </ b> A and B. Then, the power supply system 2 similar to the example shown in FIG. 12 is constructed except that the guide member 770 is omitted by using the spacer plate 840 in which the width of the convex portion is narrower and the width of the concave portion is wider.

  In this modified example, in the initial state shown in FIG. 15 (the state in which the shielding member 880 is at the reference position), the lower end openings of the refrigerant passages 247 provided at both ends 880A and B of the plate 840 are the both ends 880A of the shielding member 880. , B are completely opened to the outside through the openings 882 formed in B. On the other hand, the lower end opening of the refrigerant passage 247 provided in the central portion 840C of the plate 840 is partially shielded by the shielding portion 884 in the central portion 880C of the shielding member 880. As a result, the amount of the refrigerant C flowing through the refrigerant passage 247 at both ends and the center is, for example, approximately the same.

  When high-rate discharge is detected (for example, by the processing routine shown in FIG. 17), the shielding member 880 is moved (slid) from the reference position shown in FIG. 15 to the high-rate position shown in FIG. Then, the partial shielding of the refrigerant passage 247 provided in the central portion 840C of the plate 840 is released, and the circulation amount of the refrigerant C increases, while the opening area of the refrigerant passage 247 provided in the both end portions 840A and B is initially set. By not changing from the state, the cooling efficiency of the central portion with respect to both end portions can be increased.

  In addition, the center parts 740C and 840C of the plates 740 and 840 in the above-described embodiment are materials having higher thermal conductivity than the both end parts 740A and B and 840A and B, respectively, like the plate 240 of Example 2 (see FIG. 7). May be formed. According to the spacer plate having such a configuration, the cooling efficiency balance between the central portion and both end portions can be made to differ greatly.

  As described above, some of the preferred embodiments of the assembled battery and the power supply system including the assembled battery have been described in detail. However, the present invention is not intended to be limited to the specific embodiments.

  In addition, the assembled battery 10 shown in FIG. 1 has a simple configuration in order to explain the present invention, but various modifications and additions of equipment can be made without impairing the configuration and effects of the present invention. It is clear to the contractor. For example, when mounted on a vehicle such as an automobile, an exterior cover for protecting the main part (unit cell group, etc.) of the assembled battery, parts for fixing the assembled battery to a predetermined part of the vehicle, a plurality of assembled batteries ( However, the presence or absence of such equipment does not affect the technical scope of the present invention.

4 is a perspective view showing a configuration of an assembled battery according to Example 1. FIG. It is a side view which shows the structure of the assembled battery which concerns on one Embodiment. It is the III-III sectional view taken on the line of FIG. It is a front view which shows the example of 1 structure of a wound electrode body. 3 is a perspective view showing a spacer plate of an assembled battery according to Example 1. FIG. It is explanatory drawing which shows typically the temperature distribution image with respect to the horizontal direction of a battery. 10 is a perspective view showing a spacer plate of an assembled battery according to Example 2. FIG. 6 is a perspective view showing a spacer plate of an assembled battery according to Example 3. FIG. 10 is a perspective view showing a spacer plate of an assembled battery according to Example 4. FIG. 10 is a perspective view showing a spacer plate of an assembled battery according to Example 5. FIG. 12 is a perspective view showing a spacer plate of an assembled battery according to Example 6. FIG. 10 is an explanatory diagram illustrating a schematic configuration of a power supply system according to Example 7. FIG. In Example 7, it is sectional drawing which shows the state which has a shielding member in a reference position. In Example 7, it is sectional drawing which shows the state which has a shielding member in a high-rate position. It is sectional drawing which shows the state which has a shielding member in a reference position in the modification of Example 7. It is sectional drawing which shows the state which has a shielding member in a high-rate position in the modification of Example 7. It is a flowchart of a cooling efficiency balance adjustment routine. It is a side view which shows typically the vehicle (automobile) provided with the assembled battery or the power supply system.

Explanation of symbols

1: Automobile (vehicle)
2: Power supply system 10: Battery pack 20: Single battery 50: Container 52: Side wall (flat surface)
60: positive terminal 62: negative terminal 80: wound electrode body (electrode body)
81: Winding core portion 82: Positive electrode sheet (sheet-like positive electrode)
82A: Positive electrode side protruding portion 84: Negative electrode sheet (sheet-like negative electrode)
84A: Negative electrode side protruding portions 140, 240, 340, 440, 540, 640, 740, 840: Spacer plate (cooling mechanism)
140A, 240A, 340A, 440A, 540A, 640A, 740A, 840A: One end portion 140B, 240B, 340B, 440B, 540B, 640B, 740B, 840B: The other end portion 140C, 240C, 340C, 440C in the horizontal direction , 540C, 640C, 740C, 840C: one end 142, 243, 542 in the lateral direction: convex 144: concave (lateral groove)
245: Concave portion (vertical groove)
345: Longitudinal grooves 146, 247, 347: Refrigerant passage (cooling mechanism)
448, 548: opening 549: bracing 750: cooling control means 752: ammeter (current value detection means)
760: Electronic control unit (cooling efficiency adjusting means)
780, 880: shielding member (cooling mechanism)
782, 882: opening 784, 884: shielding part

Claims (13)

An assembled battery comprising a plurality of chargeable / dischargeable single cells and a cooling mechanism for dissipating heat generated from the single cells to the outside,
The single cell has a structure in which electrodes of a form sheet-like electrodes are wound in superposed in the longitudinal direction is accommodated in a container together with an electrolyte, the winding axis direction of the one end and the other end of the electrode body and positive terminal and the negative terminal is connected to,
The shape of the container is a flat rectangular shape, and the electrode body has a positive terminal connecting side end and a negative terminal connecting side end of the electrode body positioned at one end and the other end in the lateral direction of the container, respectively. Is contained in the container,
The assembled battery includes a plurality of unit cells arranged in a stacking direction, and includes a spacer plate disposed between flat surfaces of adjacent unit cells ,
The cooling mechanism includes a refrigerant passage formed between flat surfaces of the adjacent unit cells, and the refrigerant passage is formed facing the spacer plate,
The spacer plate, so that the cooling efficiency of their central portion is higher than that of the positive terminal connecting end portion and the negative terminal connecting side end of the electrode body, at both ends of the lateral direction of the spacer plates Compared to those , the assembled battery is composed of a material having a higher thermal conductivity at the center . 2. The spacer plate according to claim 1, wherein the spacer plate is configured such that a ratio of an area in which the flat surface of the container is exposed to the refrigerant passage is higher in the central portion than both ends in the lateral direction. Assembled battery. An assembled battery comprising a plurality of chargeable / dischargeable single cells and a cooling mechanism for dissipating heat generated from the single cells to the outside,
The unit cell has a configuration in which an electrode body in a form in which sheet-like electrodes are overlapped and wound in a longitudinal direction is housed in a container together with an electrolyte, and one end and the other end of the electrode body in a winding axis direction Are connected to the positive terminal and the negative terminal,
The shape of the container is a flat rectangular shape, wherein the electrode body, the lateral end of the positive terminal connecting end and the negative terminal connecting side end each of the containers electrode body and other It is accommodated in the container so as to be located at the end,
The assembled battery is formed by arranging a plurality of the cells in the stacking direction,
The cooling mechanism includes a refrigerant passage formed between flat surfaces of adjacent unit cells,
The positive electrode terminal connection side end of the electrode body is formed by increasing the ratio of the area where the flat surface is exposed to the refrigerant passage in the central portion of the flat surface of the container as compared with both lateral end portions thereof. The battery pack is configured such that the cooling efficiency of the central portion thereof is higher than that of the negative electrode terminal connection side end portion . Comprising a spacer plate disposed between the flat surfaces of the unit cells, the refrigerant passage is formed facing the spacer plate;
The spacer plate is formed with a groove that defines a refrigerant passage extending from one end to the other end in the horizontal direction of the plate and extending from one end to the other end in the horizontal direction.
4. A longitudinal groove extending across and intersecting the transverse groove is formed in a central portion in the transverse direction of the spacer plate, which is a groove that defines a refrigerant passage extending from the upper end to the lower end in the longitudinal direction of the plate. The assembled battery described in 1. Comprising a spacer plate disposed between the flat surfaces of the unit cells, the refrigerant passage is formed facing the spacer plate;
The spacer plate is a groove that divides the refrigerant passage from the upper end to the lower end in the vertical direction of the plate in each of one end portion, the other end portion, and the central portion in the horizontal direction of the container. A vertical groove extending from the upper end toward the lower end is formed,
4. The assembled battery according to claim 3, wherein the longitudinal grooves are formed with a larger opening width and / or a smaller pitch in the central portion than in the lateral end portions. Wherein the central portion of the lateral spacer plates, openings through the plates in the thickness direction is formed, the assembled battery according to any one of claims 1, 2, 4 and 5.   The assembled battery according to any one of claims 4 to 6, wherein the spacer plate is made of a material having a higher thermal conductivity at the center than at both ends in the lateral direction.   The assembled battery according to claim 1, wherein the single battery is a lithium ion battery.   A vehicle comprising the assembled battery according to any one of claims 1 to 8. An assembled battery comprising a plurality of chargeable / dischargeable cells and a cooling mechanism for dissipating heat generated from the cells to the outside;
Cooling control means for controlling the operation of the cooling mechanism;
A power supply system comprising:
The single cell has a structure in which electrodes of a form sheet-like electrodes are wound in superposed in the longitudinal direction is accommodated in a container together with an electrolyte, the winding axis direction of the one end and the other end of the electrode body and positive terminal and the negative terminal is connected to,
The shape of the container is a flat rectangular shape, and the electrode body has a positive terminal connecting side end and a negative terminal connecting side end of the electrode body positioned at one end and the other end in the lateral direction of the container, respectively. Is contained in the container,
The assembled battery is formed by arranging a plurality of the cells in the stacking direction,
The cooling mechanism is configured so as to change the relative cooling efficiency of the positive terminal connecting end portion and the negative terminal connection end and their central portion of the electrode body,
The cooling control means includes current value detection means for detecting a discharge current value of the assembled battery, and cooling efficiency adjustment means for changing the cooling efficiency according to the detected value, and the detected value is lower than a predetermined value. A power supply system that controls the operation of the cooling mechanism so that the relative cooling efficiency of the central portion of the electrode body is higher than that of both end portions of the electrode body when it is high. Before Symbol cooling mechanism:
Refrigerant passage formed between the flat surfaces of the adjacent unit cells, wherein the refrigerant passage is formed in the longitudinal direction of the container at each of the lateral end of the container, the other end, and the center thereof. And; and
A shielding member capable of at least partially shielding at least a portion of the refrigerant passage, the shielding member configured to control the shielding timing by the cooling control means;
The power supply system according to claim 10, comprising:   The power supply system according to claim 10 or 11, wherein the unit cell is a lithium ion battery. A vehicle comprising the power supply system according to any one of claims 10 to 12.

Images