WO2014128841A1 - Assembled battery and battery used in same - Google Patents

Abstract

Provided is an assembled battery having a high volume capacity density and including unit batteries, the temperatures of which are uniform. A plurality of batteries and a plurality of heat dissipation plates are housed in a tubular type of chassis formed by an extrusion. The heat dissipation plates are interposed between butting portions and between flexible portions, the butting portions and the flexible portions being formed on the chassis. The butting portions are made closer to each other in association with the deformation of the flexible portions. The heat dissipation plates are then fixed while being made contact with the butting portions.

Description

Battery pack and battery used therefor

The present invention relates to a plurality of secondary batteries and an assembled battery in which they are integrated.

For example, as a secondary battery for driving a vehicle, a sheet for both positive and negative electrodes (positive and negative electrode plates) as a power generation element group, a separator that separates the positive and negative electrode plates, and an electrolyte solution in a sealed battery container made of metal or resin Secondary batteries having external terminals that are housed in the battery container and are connected to both electrodes constituting the power generation element group fixed to the battery container are widely known. A lithium ion secondary battery is a typical secondary battery of this type. Conventionally, many lithium ion secondary batteries have a cylindrical appearance (cylindrical batteries). However, in order to improve mounting density due to the demand for high output and large capacity, the lithium ion secondary batteries have a rectangular (rectangular) shape ( Square batteries) and power generation elements laminated and sealed have been studied.

In order to obtain a desired output or capacity, a plurality of these single cells are mechanically integrated and are put into practical use in the state of an assembled battery or battery module electrically connected in series or in parallel. Each unit cell in the assembled battery is housed and integrated in a casing in a compressed state in the stacking direction in order to ensure vibration resistance and increase heat transfer. The voltage of each single cell is monitored and controlled with high accuracy.

Since a large charge / discharge capacity is provided in a limited vehicle space, a high volume capacity density is required for the assembled battery mounted on the vehicle.

However, it is known that the cell used changes in temperature due to internal Joule heat and chemical reaction heat during charge and discharge, and the overdischarge potential and overcharge potential change. For this reason, when each unit cell in the assembled battery is in a different temperature state, each has a different overdischarge potential and overcharge potential. As a result, at the time of charging, the amount of charge is limited by the single battery having a low overcharge potential, and it is impossible to store a sufficient amount of power in a single battery higher than this. Further, at the time of discharging, the discharge amount is limited by the single cell having a high overdischarge potential, and power that is not output remains in the single cell having a lower overdischarge potential.

That is, if the temperature of each unit cell in the assembled battery is different, the absolute amount of power reserve decreases and the amount of power that can be extracted decreases. Therefore, in order to increase the volume capacity density of the assembled battery, it is important to keep the temperature of each built-in cell uniform.

In order to reduce the temperature difference between the individual cells, for example, the assembled battery disclosed in Patent Document 1 aims to provide a battery pack in which temperature variations between internal cells are reduced. An assembled battery in which the batteries are stacked in a vertical direction, a case and lid member for storing the assembled battery, a bottom member, a tray provided between the individual cells, and the single cells connected in parallel or in series, A positive terminal and a negative terminal of the assembled battery to be connected, and a fixing means for pressing the assembled battery and fixing the lid member to the case at a preset pressure position.

Alternatively, for example, the secondary battery module disclosed in Patent Document 2 aims to provide a secondary battery and a battery module with improved output per unit weight and heat release characteristics, and the secondary battery has at least one terminal. Formed in a case with an electrode group, a groove for accommodating the electrode group, an opening that opens one side so that the electrode group passes, a film lid that extends over the opening and fixes the electrode group in the groove, and a case And a heat radiating member extending from the case toward the outside.

JP 2006-339032 A JP 2011-40379 A

In order to make the temperature of each unit cell uniform, it is desirable that the heat of each unit cell is transmitted to the casing of the assembled cell through the same path and heat flow. In addition, it is desirable that the heat of each single cell is exchanged.

For this purpose, heat transfer from each battery to the casing of the assembled battery is preferably performed in a direction orthogonal to the battery stacking direction. In order to realize this, the following measures (1) to (4) should be taken.

(1) A heat sink is interposed between the batteries stacked in the thickness direction to reduce the thermal resistance of the heat sink and the side of the housing.

(2) Reduce the thermal resistance between the heat sink and each battery.

(3) Increase the thermal resistance between the main surface of the battery at the end of the stack and the opposing housing.

(4) Reduce the thermal resistance in the housing.

On the other hand, in Patent Document 1, each tray (heat radiating plate) and the casing are in contact with each other only by the plate spring force of the tray made of a thin metal plate that is bent, and thus a large contact surface pressure can be obtained. Since the contact heat resistance with the heat sink is large, the above (1) is not satisfied.

Further, in Patent Document 2, since a large amount of contact surface passage is required for heat transfer between the enclosures, the contact thermal resistance in the enclosure is large, and the above (4) is not satisfied.

In view of the above-described case, an object of the present invention is to provide an assembled battery in which the temperature of each unit cell is uniform and the volume capacity density is high.

In order to solve the above-described problems, the assembled battery of the present invention includes a plurality of batteries, a plurality of heat sinks provided with a single metal or a layer made of a different material on a metal surface, and a plurality of mutually facing butting portions, And a housing having a flexible portion that straddles the butted portions, and a fixing member that fixes the housing. The housing includes the plurality of batteries and the plurality of heat dissipation plates, and the heat dissipation plate. Is interposed between the abutting portions, the distance between the facing abutting portions is reduced with deformation of the flexible portion, and the heat sink and the abutting abutting portion are in contact with each other. The distance between the parts is fixed.

In the present invention, it is desirable that the portion of the heat radiating plate that comes into contact with the butted portion has flexibility.

In the present invention, a flexible material may be interposed between the heat radiating plate and the butt portion.

In the present invention, a flexible material may be interposed in the flexible portion of the heat radiating plate.

In the present invention, the heat radiating plate and the housing may include a through hole, and the fixing member may be passed through the through hole.

Further, in the present invention, a plurality of the heat radiating plates may be interposed between one butted portion.

Further, in the present invention, it is desirable to provide means for selectively allowing a cooling refrigerant to contact the surface of the flexible part of the casing.

In the present invention, at least one surface of the electrode body composed of a laminate of the positive electrode sheet, the negative electrode sheet, and the separator is provided with a resin layer on both surfaces of the heat radiating plate made of a metal plate having a thickness of 0.2 mm or more. A battery that is sealed with an exterior body and is used with the heat radiating plate interposed between the butted portions may be used.

According to the present invention, the thermal resistance between the radiator plate and the housing is small, the contact thermal resistance between the battery and the radiator plate is small, the thermal resistance between the main surfaces of both stacked batteries and the opposing housing is large, The thermal resistance in the housing is reduced. Therefore, the above problem is solved.

It is a partial exploded perspective view of the assembled battery of a 1st embodiment to which the present invention is applicable. It is a perspective view of the housing used for the assembled battery of a 1st embodiment. It is a perspective view of the battery used for the assembled battery of 1st Embodiment. It is a fragmentary sectional view of the housing used for the assembled battery of a 1st embodiment. It is a fragmentary sectional view which shows the manufacturing method 1 of the assembled battery of 1st Embodiment, and shows the state which inserted the heat sink, the battery, and the heat insulation board in the housing. It is a fragmentary sectional view which shows the manufacturing method 2 of the assembled battery of 1st Embodiment, and shows the state which pressurized the housing from the outside. It is a fragmentary sectional view which shows the manufacturing method 3 of the assembled battery of 1st Embodiment, and shows the state which fixed the housing with the fixing member. It is the temperature measurement result in the time of each battery in the conventional assembled battery, and its analysis result. It is the temperature analysis result in the time of each battery in the assembled battery of the prior art and 1st Embodiment. It is a fragmentary sectional view of the assembled battery of 2nd Embodiment which can apply this invention. It is a fragmentary sectional view of the assembled battery of 3rd Embodiment which can apply this invention. It is a fragmentary sectional view of the assembled battery of 4th Embodiment which can apply this invention. It is a partial exploded perspective view of the assembled battery of 4th Embodiment. It is a fragmentary sectional view of the assembled battery of 5th Embodiment which can apply this invention. It is a fragmentary sectional view of the assembled battery of 6th Embodiment which can apply this invention. It is a fragmentary sectional view of the battery used for the assembled battery of 1st Embodiment. It is a fragmentary sectional view of the battery used for the assembled battery of 6th Embodiment.

(First embodiment)
Hereinafter, an embodiment in which the present invention is applied to an assembled battery of a secondary battery for driving a vehicle will be described with reference to the drawings.

(Constitution)
<Overall structure>
As shown in FIG. 1, the assembled battery 100 according to the present embodiment includes an integrally formed casing 101, a plurality of stacked batteries 30, a heat insulating plate 40, a fixing member 201, caps 206 and 207, and the like.

A laminated battery is used for the battery 30, and each battery 30 is formed with a positive electrode terminal 31 and a negative electrode terminal 32. In addition, each battery 30 is accommodated while being inverted 180 ° so that it can be easily connected in series with another battery 30 adjacent in the stacking direction (so that the opposite electrode terminal of the adjacent battery 30 comes close). The children 31 and 32 are electrically connected in series (electrical connection means are not shown).

Further, the positive electrode terminal 31 of the battery 30 positioned at the bottom and the negative electrode terminal 32 of the battery 30 positioned at the top are respectively connected to the positive electrode external terminal 203 and the negative electrode external terminal 204.

The casing 101 is fixed in a state of being pressed in the stacking direction of the battery 30 by a plurality of fixing members 201 arranged on the side surface portion.

The opposing two surfaces of the casing 101 where the battery 30 and the heat insulating plate 40 are exposed are sealed with caps 206 and 207, respectively. Insulating polybutylene terephthalate (PBT) is used as a material for the caps 206 and 207.

<Housing>
As shown in FIG. 2, the casing 101 has a substantially rectangular parallelepiped shape, and an upper surface 105 and a lower surface 106 are formed. A plurality of flexible portions w <b> 1 are formed between the upper surface 105 and the lower surface 106. ing. Each flexible portion w1 is configured to have a smaller thickness than the periphery thereof and can be deformed relatively easily by an external force. The upper surface 105, the heat radiating plate portion 104 (not shown in FIG. 2) immediately below the upper surface 105, and the side surface portion on which the flexible portion w1 is formed are a single material, that is, one piece, and have a uniform shape in the depth direction. ing. The dimensions in the width direction, height direction, and depth direction of the casing 101 are determined in consideration of the dimensions of the heat insulating plate (not shown) and the battery to be accommodated.

The casing 101 is formed by an extrusion process to be described later, and an A6000 series (magnesium-silicon series) aluminum alloy is used as a material.

FIG. 4 is a view of the casing 101 as seen from the battery insertion direction. The two abutting surfaces 205 that will be abutted in the future are formed in a portion adjacent to each flexible portion w1. A gap h1 is provided between the butted surfaces 205. A heat sink 41 is disposed between the batteries 30, and a gap 43 in which each heat sink 41 is accommodated is formed in the housing 101.

<Battery>
As shown in FIG. 3 inserted into the casing 101, the battery 30 is sealed in a substantially rectangular outer package 33 in plan view, and the positive electrode terminal 31 and the negative electrode terminal 32 are drawn from one side of the outer package 33. I am doing. Such a battery is generally called a laminated battery.

Each of the positive electrode terminal 31 and the negative electrode terminal 32 has a flat plate shape, and is connected to a plurality of sheet-like positive electrodes and sheet-like negative electrodes inside the outer package 33.

Subsequently, a more detailed structure of the battery 30 will be described with reference to FIG. As shown in FIG. 16, the exterior body 33 is composed of a laminate film having a heat-sealing resin layer 34 on the inner surface of the battery 30.

The exterior body 33 (laminate film) is configured by laminating an exterior resin layer 36, a metal layer 35, and a heat-sealing resin layer 34 in order from the outside of the battery. The outer package 33 is bent into two upper and lower sides on the side opposite to the side where the positive electrode terminal 31 and the negative electrode terminal 32 of the battery are formed, and the upper and lower heat-sealing resin layers 34 are heat-sealed around the electrode part 37. Thus, the exterior body 33 is hermetically sealed. The exterior resin layer 36 is made of polyester (PE) and has a thickness of 50 μm. The metal layer 35 is made of an aluminum alloy and has a thickness of 100 μm. A modified polyolefin film is used for the heat sealing resin layer 34, and the thickness thereof is 50 μm.

A vent portion (not shown) is formed in a part of the heat-sealed portion so as to have a lower strength than the other portions. In the vent part, when the internal pressure of the battery rises abnormally, it is destroyed before the other parts and the internal pressure is released.

In the exterior body 33, a laminated electrode body in which a plurality of sheet-like positive electrodes and a plurality of sheet-like negative electrodes are laminated via separators is built in and infiltrated with an electrolytic solution. An electrode body 37 is formed of a laminate composed of a plurality of sheet-like positive electrodes, sheet-like negative electrodes, and separators.

In the sheet-like positive electrode, a layer (positive electrode mixture layer) made of a positive electrode mixture containing a positive electrode active material, a conductive additive mainly composed of a carbon material, and a binder is formed on the surface of the positive electrode current collector. .

An aluminum alloy foil having a thickness of 0.015 mm is used for the positive electrode current collector.

The positive electrode mixture layer is a mixture of LiCoO 2 as a positive electrode active material, acetylene black as a conductive auxiliary agent, PVDF as a binder, and the like, and has a thickness per side of 30 to 100 μm.

An aluminum alloy with a thickness of 0.2 mm is used for the positive electrode terminal.

In the sheet-like negative electrode, a layer (negative electrode mixture layer) made of a negative electrode mixture containing a negative electrode active material, a conductive additive, a binder and the like is formed on the surface of the negative electrode current collector.

A copper alloy having a thickness of 0.01 mm is used for the negative electrode current collector.

The negative electrode mixture layer is made of a composition such as graphite as a negative electrode active material and styrene butadiene rubber (SBR) or carboxymethyl cellulose (CMC) as a binder, and has a thickness per side of 30 to 100 μm. .

As the negative electrode terminal, a surface of a 0.15 mm thick copper alloy with nickel plating is used.

As the separator, a polyolefin microporous film having a thickness of 25 μm and a porosity of 30 to 70% is used.

As the electrolytic solution, a solution (nonaqueous electrolytic solution) in which a solute such as LiPF6 is dissolved in an organic solvent mainly composed of ethylene carbonate (EC) is used.

<Heat insulation plate>
As shown in FIG. 1, the heat insulating plate 40 has a substantially rectangular shape. A foamable resin is used as the material.

<Heat sink>
As shown in FIG. 5, the heat sink 41 has a flat plate shape, and an aluminum alloy having a thickness of 0.5 mm is used as the material. Each flat portion is configured to be slightly larger than the main surface of the battery 30 or the heat insulating plate 40 (the surface facing the heat radiating plate). The end portion of the heat radiating plate 41 is bent into a substantially triangular shape in cross-sectional shape to form a flexible portion w2, which is bent according to an external force from the vertical direction in the drawing.

(Production method)
Next, with reference to FIG. 5, FIG. 6, and FIG. 7, the manufacturing method of the assembled battery of this embodiment is demonstrated. It should be noted that the present invention is not limited to the manufacturing method exemplified below.

<Overview>
The manufacturing process of the assembled battery 100 of the present embodiment includes (1) a battery manufacturing step for manufacturing the battery 30, (2) a housing manufacturing step for manufacturing the housing 101, and (3) a heat sink 41 and a heat insulating plate 40 on the housing 101. A component housing step for housing a component such as the battery 30; (4) a pressure fixing step for applying a surface pressure to the housing component by pressurizing the housing 101 from the outside and adjusting an outer dimension of the housing 101; A terminal connection / sealing step of electrically connecting the positive and negative terminals 31, 32 of each battery 30 in a predetermined combination and sealing with caps 206, 207 is included. Hereinafter, the steps will be described in the order described above.

<Battery fabrication steps>
96% by mass of LiCoO2, 2% by mass of acetylene black, and 2% by mass of PVDF are mixed, and N-methyl-2-pyrrolidone (NMP) is further added to prepare a positive electrode mixture-containing paste.

The obtained positive electrode mixture-containing paste is applied to both surfaces of the positive electrode current collector, dried, and then subjected to press treatment to form a positive electrode mixture layer, thereby obtaining a sheet-like positive electrode.

The obtained sheet-like positive electrode is cut into a shape including a rectangular positive electrode mixture layer forming portion and an exposed portion of the rectangular positive electrode current collector.

On the other hand, a binder composed of 1.5% by mass of SBR and 0.5% by mass of CMC is added to 98% by mass of graphite and mixed, and water is further added to prepare a negative electrode mixture-containing paste.

The obtained negative electrode mixture-containing paste is applied to both surfaces of the negative electrode current collector, dried, and then subjected to a press treatment to form a negative electrode mixture layer, whereby a sheet-like negative electrode is obtained.

The obtained sheet-like negative electrode is cut into a shape including a rectangular negative electrode mixture layer forming portion and an exposed portion of the rectangular negative electrode current collector.

Next, 10 sheet-like positive electrodes and 11 sheet-like negative electrodes are laminated via a separator to obtain a laminated electrode body. At this time, lamination is performed so that both ends of the laminated electrode body become negative electrodes.

Next, the current collector exposed portion of each sheet-like positive electrode is ultrasonically welded to the positive electrode terminal made of aluminum alloy, and the current collector exposed portion of each sheet-like negative electrode is ultrasonically welded to the negative electrode terminal made of copper alloy. In addition, the positive electrode terminal and the negative electrode terminal have an adhesive layer made of the same modified polyolefin as the resin constituting the heat-sealing resin layer of the outer package on both sides of the portion that is supposed to be located in the heat seal portion of the outer package. Arrange.

Next, a laminate film is prepared, and the laminated electrode body is placed on the heat-fusing resin layer 34 of the laminate film so that a part of the positive electrode terminal 31 and the negative electrode terminal 32 protrudes, and the laminate film is wrapped so as to wrap the laminated electrode body. Fold it in half.

Then, each side where the laminate film is stacked is heat-sealed except for a part to form an outer package 33, which is vacuum-dried at 70 ° C. for a certain time.

Subsequently, an electrolytic solution is injected from a part of the side that is not heat-sealed, and the part is heat-sealed and sealed in a reduced pressure state.

The laminated electrode body and the sealed outer body containing the non-aqueous electrolyte are aged for a certain period of time, and then subjected to a chemical conversion treatment by charging with a predetermined current and voltage profile. Get a battery.

<Housing body production step>
A billet made of aluminum alloy raw material formed by casting is cut into an appropriate length in advance.

¡The billet is heated to around 500 ° C, which is close to the melting point of the material, and at the same time, the die that is the mold is preheated.

The billet is pushed out along the shape of the die with a pressing force of 1000 tons or more by the piston of the press machine. The billet that has been extruded and has a predetermined cross-section is slightly twisted or distorted during the cooling process, and is stretched and straightened from both ends.

Next, surface treatment is performed to adjust the electrical insulation and corrosion resistance of the surface.

After that, the extrusion direction is cut to the required length and post-processing is performed. After becoming a housing shape, heat treatment for obtaining necessary strength and hardness is performed to obtain a housing 101.

<Parts accommodation step>
As shown in FIG. 5, first, a total of seven heat radiating plates 41 are respectively inserted into predetermined positions from the opening surface of the prepared casing 101. Thereby, a fixed space is formed between the heat radiating plates 41. For each formed space, the heat insulating plate 40 is inserted into the space adjacent to the upper surface 105 and the lower surface 106 of the housing, and the battery 30 is inserted into the other space. Since each space is formed in advance with a size larger than these parts to be inserted, these parts can be inserted without difficulty.

In order to facilitate connecting the adjacent batteries 30 in series in the terminal connection / sealing step (that is, the terminals of the positive and negative opposite poles are positioned closest to each other), the direction of each battery is alternately reversed. Further, a part of the outer shape of each battery 30 (the outer peripheral edge portion 134 in FIG. 5) abuts on the inner wall of the casing 101, and the relative position in the paper surface horizontal direction between the battery 30 and the casing 101 is determined. The insertion amount of each battery 30 and the heat insulating plate 40 in the depth direction of the drawing is managed by a jig.

<Pressure fixing step>
As shown in FIG. 6, the upper surface 105 and the lower surface 106 of the housing 101 are pressurized in the direction of arrow Y. When pressing, rigid parallel plates (not shown) are applied as jigs so that the upper surface 105 and the lower surface 106 are not deformed by the reaction force of the battery 30 or the heat insulating plate 40 inserted.

Due to the pressurization, the flexible portions w1 and w2 are bent and deformed so that the gap h1 approaches 0. At the same time, the distance between the heat radiating plates 41 approaches the thickness of the battery 30 and the heat insulating plate 40, and then the upper and lower heat radiating plate portions. 104 compresses the battery 30 and the heat insulating plate 40. When the pressurization is further continued, the gap h1 becomes 0 (that is, the butted surfaces 205 of the casings 101 constituting the gap h1 come into contact with each other). No longer deforms. At the same time, the flexible portion w2 of the heat radiating plate 41 has as its internal force a force to return to the initial shape as shown in FIG.

As shown in FIGS. 7 and 1, a rigid fixing member 201 is applied from the upper surface 105 to the lower surface 106 of the housing 101, and is hooked on the hook 42 formed on the housing 101 to prevent return and fix. This prevents the housing 101 from returning to its original shape due to the springback after the applied pressure is removed.

In this step, the flexible portions w1 and w2 may be fixed in an elastically deformed state, or may be fixed in a deformed state accompanied by plastic deformation.

<Terminal connection / sealing step>
Since the stacked batteries are in a state where the positive and negative terminals to be connected are close to each other, the metal bus bars are assigned to each combination by ultrasonic welding. The positive electrode terminal 31 and the negative electrode terminal 32 which are the extremes in series are connected to the positive and negative external terminals 203 and 204 previously incorporated in the cap 206 shown in FIG. 1 by ultrasonic welding. Thereby, the electrical contact between the assembled battery and the outside is determined.

The caps 206 and 207 are placed on the terminal connection portion and the opposite surfaces (that is, the front and rear end surfaces in the pushing direction of the casing) and sealed to obtain an assembled battery.

(Effects etc.)
Next, the effects and the like of the assembled battery of this embodiment will be described.

According to the assembled battery of the present embodiment, each battery and the heat radiating plate are always pressed with a predetermined load, so that the contact thermal resistance between the battery and the heat radiating plate can be reduced.

In addition, since the heat sink and the housing can ensure sufficient contact between the heat sink and the housing by the internal force (spring restoring force) remaining in the flexible portion w2 of the heat sink, the contact thermal resistance is reduced. it can. Moreover, since the housing is integral, the thermal resistance in the housing can be reduced.

Moreover, the thermal resistance between the main surface of the battery at both ends of the stack and the casing can be increased by the heat insulating material, and the main path of the heat dissipation path of each battery 30 constituting the assembled battery 100 is used as a path to the side surface portion of the casing 101. Therefore, the temperature unevenness of each battery 30 can be suppressed.

From the above, since the heat of each battery is equally transmitted in the vertical direction of the battery stacking direction, the temperature of each battery can be made uniform, and the above-described purpose can be achieved.

Furthermore, in the assembled battery of the present invention, since the dimensions of the battery housing portion and the heat insulating plate housing portion are larger than the thickness of the battery and heat insulating plate to be housed, these can be inserted and housed easily.

Furthermore, in the assembled battery of the present invention, the amount of crushing of the battery housing part and the heat insulating plate housing part is automatically managed to a constant value by the abutting surfaces 205 of the housings coming into contact with each other. The surface pressure of the parts is controlled to be constant, and the characteristics of the battery and the heat insulating plate can be stabilized.

The results of the temperature measurement and heat conduction analysis of the assembled battery conducted to confirm the above-described effects and the like will be described.

<Measurement of battery temperature>
The temperature of each battery in the assembled battery in which the thermal contact between the conventional heat sink and the casing was not good was measured.

7 laminate batteries having a rated capacity of about 10 Ah were laminated in the thickness direction, and 8 heat sinks made of aluminum alloy having a thickness of 0.5 mm were interposed between the batteries. Each radiator plate was bent at 4 mm at both ends so that the angle was 80 degrees without including the springback. At both ends of the laminate, a foaming resin having a thickness of 4 mm and a surface area substantially equivalent to that of the battery was disposed as a heat insulating plate. These were accommodated in a 2 mm thick housing made of aluminum alloy, the dimensions of which were adjusted so that the bent end face of the heat sink was in contact, and fixed by applying a compressive load of about 200 N in the battery stacking direction.

The positive and negative terminals of adjacent batteries are clamped and fixed in series by sandwiching a 0.2 mm thick copper alloy plate into two folded bus bars, and the terminal positive and negative terminals are connected to positive and negative external connection terminals. A battery pack was constructed by connecting to each. A thermocouple was attached to the surface of the central part of the main surface of each battery accommodated so that the temperature of each battery could be measured. The positive and negative external connection terminals were respectively connected to the battery charge / discharge equipment via the harness, and were fully charged in advance by the charge / discharge equipment. After a sufficient rest time with the ambient temperature kept at 25 ° C., discharge was performed at a constant condition of 30 A so that cooling air hits the surface of the assembled battery (that is, the surface of the housing), and the temperature of each battery at 1200 s from the start of discharge. Evaluated.

Fig. 8 shows the measurement results with thin ink triangles. The horizontal axis in FIG. 8 is the stacking order of the batteries, # 01 indicates the bottom of the stack, and # 07 indicates the battery at the top of the stack. # 04, that is, the temperature of the battery at the center of the stack became the highest, and decreased as it approached the upper and lower ends of the stack. In the battery having the highest temperature, the temperature was about 43 ° C. from the initial stage (25 ° C.), and increased by about 18 ° C. There was a temperature difference of 2 to 3 ° C. between the battery with the highest temperature and the battery with the lowest temperature.

<Heat conduction analysis of battery pack>
An attempt was made to reproduce the above measurement by analysis. Two-dimensional unsteady heat conduction analysis conditions were used, and the shape of the half of the cross section of one side of the assembled battery (similar to FIG. 7) was modeled as the left-right symmetry of the actual machine shape. As the material constants of the heat sink, heat insulating plate, and housing, the thermal conductivity is 236 W / m · K, 0.1 (same), 236 (same) in order, and the specific heat is 900 J / kg · K, 2000 (same), 900 (same as above) and density of 2700 kg / m ^ 3, 85 (same as above) and 2700 (same as above) were used for the analysis. Further, since the battery has a laminated structure of composite materials, the equivalent material constant as the battery obtained by considering the material constant and the usage amount of each material was used. The thermal conductivity was 1 W / m · K in the thickness direction (stacking direction), 40 in the width direction (same), the specific heat was 954 J / kg · K, and the density was 2000 kg / m ^ 3. The interface between each heat sink and the housing was assumed to have insufficient thermal contact, and infinite thermal resistance was given.

Fig. 8 shows the analysis results with white triangles. Since the analysis result almost overlaps the actual measurement result, it is determined that this analysis condition is appropriate. Under this analysis condition, in order for the heat of each battery to be transferred to the housing and cooled by the cooling air, all heat must be transferred via the adjacent battery and the heat insulating plate having a large thermal resistance. A temperature difference is required between them. The fact that the actual measurement results were well reproduced under these analysis conditions suggests that the heat transfer of the actual machine was performed through an unfavorable route through the heat insulating plate, hardly passing through the route from the heat sink to the housing. Yes. That is, it became clear that thermal contact with the housing by the spring force of the thin and small heat sink cannot be expected.

Next, an analysis to reproduce the characteristics of this embodiment was attempted. In the model of the same shape and material constant as in the above analysis, a thermal resistance of 0.01 K / W obtained by a preliminary experiment was given to the interface between each heat sink and the housing.

Fig. 9 shows the analysis results with open circles. For comparison, the analysis results shown in FIG. 8 are also shown. It can be seen that the battery temperatures of the present embodiment are generally lower than the analysis results of FIG. 8, and the temperature variations of the batteries are small. This suggests that the heat of each battery was transferred to the housing through the end of the heat sink close to each battery.

As described above, the effectiveness of the present embodiment has been clarified from the temperature measurement and analysis of each battery in the assembled battery.

(Second Embodiment)
Next, a second embodiment in which the present invention is applied to an assembled battery of a vehicle driving secondary battery will be described. The assembled battery of the present embodiment is obtained by changing the thermal contact form of the interface between the heat sink and the housing. In addition, in embodiment below this embodiment, the same code | symbol is attached | subjected to the member same as 1st Embodiment mentioned above, the description is abbreviate | omitted, and only a different location is demonstrated hereafter.

As shown in FIG. 10, in the assembled battery 110 of the present embodiment, the heat radiating plate 51 is configured in a flat plate shape including the end portions. A flexible material 116 is provided at the interface between the heat sink 51 and the casing 111. Foamed resin is used for the flexible material 116.

The flexible material 116 is fixed in a compressed state in the thickness direction (that is, with a thickness dimension smaller than the original thickness).

According to the assembled battery 110 of the present embodiment, the illustrated lower surface of the heat radiating plate 51 and the housing 111 are brought into contact with each other by an internal force (force to return to the original shape) due to the flexible material 116 being fixed in a compressed state. A large surface pressure can be applied to the surface. Therefore, since the abutting surface 205 of the housing 101 and the heat radiating plate 51 can be brought into close contact with each other, the contact thermal resistance can be effectively reduced.

In the present embodiment, the flexible material 116 may be disposed as a separate component between the heat sink 51 and the casing 111 at the stage of the component housing step, or temporarily placed in a predetermined position on the heat sink 51 or the casing 111. It may be stopped.

In addition, a foam metal may be used as the material of the flexible material 116. In this case, the thermal conductivity thereof is higher than that in the case of using the foam resin, and therefore the heat sink 116 and the casing 111 through the flexible material 116 are used. This heat transfer can also be performed effectively. (The point that the second embodiment is superior to the first embodiment will be described.)

(Third embodiment)
Next, a third embodiment in which the present invention is applied to an assembled battery of a vehicle driving secondary battery will be described. The assembled battery of the present embodiment is obtained by further changing the thermal contact mode at the interface between the heat sink and the housing.

As shown in FIG. 11, in the assembled battery 120 of the present embodiment, the end of the heat radiating plate 61 is bent into a U shape to form a flexible portion w3. A flexible material 126 is provided on the inner periphery of the U-shaped bending portion. Foamed resin is used for the flexible material 126.

The flexible material 126 is fixed in a compressed state in the thickness direction. The flexible portion w3 is fixed in a deformed state compared to the original shape.

According to the assembled battery 120 of this embodiment, a large surface pressure can be applied to the contact surface between the heat sink 61 and the housing by the resultant force of the internal force of the flexible material 126 and the internal force of the flexible portion w3 of the heat sink 61. Therefore, the contact thermal resistance can be effectively reduced. Moreover, since the heat sink 61 and the housing 121 can be brought into contact with each other on two surfaces (that is, the upper surface and the lower surface of the U-shaped bent portion), the heat transfer area can be increased compared to the second embodiment. The contact thermal resistance can be effectively reduced.

(Fourth embodiment)
Next, a fourth embodiment in which the present invention is applied to an assembled battery of a vehicle driving secondary battery will be described. The assembled battery of the present embodiment has improved cooling performance from the assembled battery surface, that is, the housing surface.

As shown in FIGS. 12 and 13, the assembled battery 130 of this embodiment includes a duct 208 that covers a side surface including the flexible portion w <b> 1 group of the housing 131. A fixing member 221 is provided on the outer side of the duct 208. The duct 208 is formed by injection molded PBT. A connection interface unit 230 (see FIG. 13) with an external duct is further formed at both ends of the duct 208 in the assembled battery depth direction. One of the two connection interfaces introduces cooling refrigerant and the other exhausts.

The space defined by the duct 208 and the casing 131 (see FIG. 12) constitutes a cooling refrigerant flow path 209. The fixing member 221 functions to prevent the casing 131 from returning to its original shape, and at the same time, prevent the duct 208 from being deformed or dropped. Air introduced from outside by a fan is used as the cooling refrigerant.

According to the assembled battery 130 of the present embodiment, the heat transmitted from each battery 30 to the housing 131 through each heat sink 41 is immediately released to the outside through the cooling refrigerant on the surface of the housing 131, and thus the upper surface of the housing 131. 105, the diffusion to the lower surface 106 can be reduced, and it is not necessary to directly apply the cooling refrigerant to the upper surface 105 and the lower surface 106. As a result, a plurality of assembled batteries 130 are arranged closer to each other to configure a large-scale power storage system. In this case, it is not necessary to prepare a gap through which the cooling refrigerant flows on the upper surface 105 or the lower surface 106. Therefore, it becomes possible to arrange a plurality of assembled batteries 130 with higher density.

(Fifth embodiment)
Next, a fifth embodiment in which the present invention is applied to an assembled battery of a vehicle driving secondary battery will be described. The assembled battery of the present embodiment is obtained by further changing the thermal contact mode at the interface between the heat sink and the housing.

As shown in FIG. 14, in the assembled battery 140 of the present embodiment, each heat radiating plate 71 is configured in a flat plate shape including an end portion. A through-hole 231 in the thickness direction is formed at the end of each heat radiating plate 71, that is, at the portion that contacts the housing 141. A through hole 232 is also formed in a portion of the housing 141 that coincides with the through hole 231. The through holes 231 of the heat radiating plates 71 are formed at the same position, and the through holes 232 of the housing 141 penetrate the housing 141. Further, the shaft 233 passes through the through holes 231 and 232, and both ends are fixed by caulking 234 in a state where the interfaces between the heat radiating plates 71 and the housing 141 are in contact with each other.

According to the assembled battery 140 of the present embodiment, each heat sink 71 and the casing 141 are fixed by the caulking 234 in a state of being in good thermal contact with a sufficient surface pressure, so that the contact thermal resistance is effectively reduced. Can be made.

In the present embodiment, a plurality of shafts 233 may be provided in the illustrated depth direction. Further, the mechanical functions of the shaft 233 and the caulking 234 may be achieved by bolts and nuts (how to raise the claim of this embodiment, what to deal with the problem of unity? The point of the present invention is the possibility of the housing) And the heat sink has a flexible part).

(Sixth embodiment)
Next, a sixth embodiment in which the present invention is applied to an assembled battery of a vehicle driving secondary battery will be described. The assembled battery of the present embodiment is a battery provided with the function of a heat sink.

As shown in FIG. 15, in the assembled battery 150 of the present embodiment, the battery 35 has a peripheral heat-sealed portion in contact with the housing 141 and is sandwiched between the housing 141 from above and below. The batteries 35 at the upper and lower ends of the stack are each sandwiched between the casings 141, and the other batteries 35 located near the center of the stack are sandwiched two by two.

As shown in FIG. 17, in the battery 35 of the present embodiment, the lower packaging body 39 in the figure includes a heat dissipation plate 81 in which a heat fusion layer 43 is formed inside the battery 35 and an exterior resin layer 38 is formed outside. It is comprised by the exterior body 39 containing. The heat sink 81 is made of an aluminum alloy and has a thickness of 0.5 mm. A modified polyolefin film is used for the heat-sealing layer 43, and the thickness is 50 μm. The exterior resin layer 38 is made of polyester (PE) and has a thickness of 50 μm. The upper outer packaging body 33 and the lower outer packaging body 39 are arranged so as to sandwich the electrode body 37, and then the upper lower thermal sealing resin layers 34 and 38 are heat sealed around the electrode portion 37. As a result, the exterior bodies 33 and 39 are hermetically sealed.

According to the assembled battery 140 of the present embodiment, the exterior body 39 (and 33) including the heat radiation plate 81 integrated in advance with the battery 35 is in direct contact with the housing 141, and sufficient contact pressure acts on the contact portion. Therefore, the contact thermal resistance between the heat sink 81 and the housing 141 can be reduced. Further, since the battery 35 and the heat radiating plate 81 are mechanically integrated in advance by heat fusion, it is possible to reduce the number of housed parts (the number of parts constituting the assembled battery) in the part housing step. In addition, since the number of members interposed between the electrode portion 37 and the heat radiating plate 81 is reduced (the metal layer on the lower side of the battery shown in FIG. 16 is eliminated), the thermal resistance from the electrode portion 37 to the heat radiating plate 81 is reduced. As a result, the heat of the battery 35 can be more effectively transferred to the heat sink.

In this embodiment, in order to further increase the amount of heat transfer, another heat radiating plate may be provided between the batteries 35, and may be sandwiched between the two batteries 35 and the housing 141. In this embodiment, the thickness of the heat radiating plate 81 is 0.5 mm. However, in order to effectively transfer the heat of the battery 35 to the housing 141, it is desirable that the thickness be 0.2 mm or more. In the present embodiment, the heat radiating plate 81 is provided only on the lower exterior body 39 in the figure, but it may be provided on the upper exterior body 33 in the figure.

Although the embodiments to which the present invention can be applied have been described so far, the present invention can be carried out with the following modifications.

(1) In the above embodiment, the lithium ion secondary battery is exemplified, but the present invention is not limited to this, and can be applied to secondary batteries in general.

(2) The casing is not limited to the A6000 series aluminum alloy exemplified in the above embodiment, but may be made of an A1000 series aluminum alloy having excellent extrudability and higher thermal conductivity.

(3) The casing is not limited to the aluminum alloy exemplified in the above embodiment, but may be made of polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), and other resins.

(4) In the above-described embodiment, the thickness of each heat radiating plate in one assembled battery is illustrated equally, but the thickness may be changed according to the part. Thereby, the heat flow of each battery can be equalized more finely.

(5) In the above embodiment, the heat insulating plates are in the shape of a rectangular parallelepiped, and one heat dissipating plate is provided at each of the upper end and the lower end in the battery stacking direction. Alternatively, each may be a variant other than a rectangular parallelepiped. Thereby, the function which suppresses a deformation | transformation of a housing pressurization direction can be given to a partition, and the deformation | transformation of the heat insulation board accommodating part at the time of a housing pressurization can be stabilized.

(6) The casing may be anodized as necessary for improving insulation or protecting the surface.

(7) In the above embodiment, the housing shape after the battery or the like is accommodated is fixed by a separately provided fixing member, but the present invention is not limited to this, and the housing is pressurized in the pressure fixing step. In this state, ultrasonic welding may be performed from the upper and lower surfaces of the housing, and a plurality of butted portions may be welded and fixed. Moreover, you may fix each butt | matching part by methods, such as resistance welding, respectively.

(8) In the above-described embodiment, a heat sink made of a single metal has been disclosed. However, the present invention is not limited to this, and a multi-material laminate in which an insulating material made of resin is applied to the surface of the heat sink. It is good. A sheet of insulating material made of resin may be interposed between the battery and the heat sink. By these, even if the exterior resin layer on the surface of the battery is broken for some reason, it is possible to avoid a problem that the exterior bodies of adjacent batteries are short-circuited.

(9) In the above embodiment, lithium cobaltate was exemplified as the positive electrode active material, and graphite was exemplified as the negative electrode active material. However, the present invention is not limited to these, and an active material usually used for a lithium ion secondary battery. Can also be used. The positive electrode active material is a material capable of inserting and removing lithium ions, and a lithium transition metal composite oxide in which a sufficient amount of lithium ions has been inserted in advance may be used. A material in which a part of lithium or a transition metal is substituted or doped with an element other than those may be used. Moreover, there is no restriction | limiting in particular also about the crystal structure of lithium transition metal complex oxide, You may have any crystal structure of a spinel system, a layer system, and an olivine system. On the other hand, as the negative electrode active material other than graphite, for example, carbon materials such as coke and amorphous carbon can be mentioned, and the particle shape is also particularly limited such as scaly, spherical, fibrous, and massive. It is not a thing.

(10) The conductive material and the binder exemplified in the above embodiment are not particularly limited, and any of those normally used in lithium ion secondary batteries can be used. Examples of binders that can be used in other embodiments include polytetrafluoroethylene, polyethylene, polystyrene, polybutadiene, butyl rubber, nitrile rubber, styrene / butadiene rubber, polysulfide rubber, nitrocellulose, cyanoethyl cellulose, various latexes, acrylonitrile, fluorine. Examples thereof include polymers such as vinyl fluoride, vinylidene fluoride, propylene fluoride, and chloroprene fluoride, and mixtures thereof.

(11) In the above embodiment, the nonaqueous electrolytic solution in which LiPF6 is dissolved in an ethylene carbonate-based organic solvent such as ethylene carbonate is exemplified. However, nonaqueous electrolysis in which a general lithium salt is used as an electrolyte and this is dissolved in an organic solvent. A liquid may be used, and the present invention is not particularly limited to the lithium salt or organic solvent used. For example, as the electrolyte, LiClO4, LiAsF6, LiBF4, LiB (C6H5) 4, CH3SO3Li, CF3SO3Li, or a mixture thereof can be used. As the organic solvent, diethyl carbonate, propylene carbonate, 1,2-diethoxyethane, γ-butyrolactone, sulfolane, propionitrile, or a mixed solvent in which two or more of these are mixed can be used.

(12) In the above embodiment, in the terminal connection between the batteries, ultrasonic welding was performed by bringing a metal bus bar into contact between the terminals to be connected. May be directly contacted with each other, and an insulating material may be interposed so as not to contact with other terminals, and the bolts made of an insulating material may be collectively screwed and connected in the stacking direction.

(13) A stainless steel film may be used for the metal layer of the laminate film.

(14) In the above embodiment, the battery and the heat insulating plate are shown as the components to be accommodated in the housing, but other structures such as an assembled battery control circuit and a voltage detection circuit for each battery may be accommodated.

Since the present invention provides a secondary battery capable of minimizing deterioration due to temperature, it contributes to the manufacture and sale of secondary batteries, and thus has industrial applicability.

30, 35 Battery 31 Positive electrode terminal 32 Negative electrode terminal 33 Exterior body (laminate film)
39 exterior body 34, 43 heat-sealing resin layer 35 metal layer 36, 38 exterior resin layer 37 electrode body 40 heat insulating plate 41, 51, 61, 71, 81 heat sink 42 hook 100, 110, 120, 130, 140 assembled battery 101, 111, 121, 131, 141 Housing 105 Upper surface 106 Lower surface
116, 126 Flexible material
117 Gap 118 Concavity and convexity 201, 211, 221 Fixing member 202 Screw member
203 Positive external terminal
204 Negative external terminal
205 Butting surface 206, 207 Cap
208 Duct
209 Flow path 230 Connection interface portion 231, 232 Through hole 233 Shaft 234 Caulking 351 Battery can 352 Battery lid 355 End plate portion 356, 359 Rib 357 Through hole 358 End plate b Bending portion h1 Gap Y Pressure direction w1, w2, w3 , W4 flexible part

Claims (8)

1. Multiple batteries,
   A plurality of heat sinks with a single metal layer or a layer made of a different material on the surface of the metal,
   A plurality of abutting portions facing each other, and a housing having a flexible portion straddling each of the butting portions,
   A fixing member for fixing the housing;
   With
   Housing the plurality of batteries and the plurality of heat sinks in the housing;
   Interposing the heat sink between the butted portions,
   The distance between the facing abutting portions is reduced with the deformation of the flexible portion, and the distance between the facing abutting portions is fixed in a state where the heat sink and the facing abutting portion are in contact with each other. The assembled battery.
2. The assembled battery according to claim 1, wherein a portion of the heat radiating plate that comes into contact with the abutting portion has flexibility.
3. The assembled battery according to claim 1, wherein a flexible material is interposed between the heat radiating plate and the abutting portion.
4. The assembled battery according to claim 1, wherein a flexible material is interposed in the flexible portion of the heat radiating plate.
5. The assembled battery according to claim 1, wherein the heat radiating plate and the housing include a through hole, and the fixing member is passed through the through hole.
6. 2. The assembled battery according to claim 1, wherein a plurality of the heat radiating plates are interposed between the butted portions.
7. The assembled battery according to any one of claims 1 to 6, further comprising means for selectively supplying a cooling refrigerant to the surface of the flexible portion of the casing.
8. The battery accommodated in the assembled battery according to any one of claims 1 to 7, wherein at least one surface of an electrode body made of a laminate of a positive electrode sheet, a negative electrode sheet and a separator is made of a metal plate having a thickness of 0.2 mm or more. A battery characterized in that it is sealed with an exterior body comprising a resin layer on both sides of a heat radiating plate, and is used with the heat radiating plate interposed between the butted portions.

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