JP2012174570A - Battery pack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery pack composed of plural unit cells capable of operating at temperatures above room temperature, which can keep the internal temperature of each unit cell uniform and furthermore can raise the temperature of each unit cell to an operating temperature quickly and also reduce the whole size of the battery accommodated in a heat insulated container to make it compact.SOLUTION: Inside an enclosure 2 as a heat insulated container constituting a battery pack 10 are accommodated nine pieces of a flat shaped unit battery pack 1 which are laminated in the thickness direction thereof. The unit battery packs 1 themselves are arranged in such a way that unit cells as the constituent elements thereof are stuck fast to each other's side faces to compose the whole battery pack 10. A heater 3 for heating the unit battery packs 1 is placed in between adjacent unit battery packs 1 in such a way that the wide face thereof is in contact with the wide faces of the unit battery packs 1.

Description

  The present invention relates to an assembled battery in which a plurality of unit cells operated at a temperature higher than room temperature are connected, and more particularly to an assembled battery suitable for a molten salt battery.

Development of relatively large secondary batteries for power storage and automobiles is ongoing. In order to obtain a desired voltage and a desired capacity, an assembled battery in which a plurality of unit cells (single cells) are connected in series and parallel is used.
As an assembled battery operated at room temperature, an assembled battery in which a plurality of unit cells of lithium ion batteries and nickel manganese batteries are connected is known. In this assembled battery, heat is generated in each unit cell constituting the assembled battery at the time of charging / discharging. Therefore, it is required to ensure the heat dissipation of the assembled battery so that the generated heat can be quickly cooled. . For example, in patent document 1, the heat dissipation of the assembled battery is enhanced by sandwiching a spacing plate (spacer) that can function as a heat dissipation member between adjacent unit cells.

As an assembled battery operated at a temperature higher than room temperature, an assembled battery in which a plurality of sodium sulfur battery cells are connected is known. This assembled battery is housed in a vacuum insulation container for heat insulation, and for safety reasons, the gap between each unit cell is filled with insulating sand, and the unit cell is fixed so as not to shake, and at the same time, locally. Abnormal heating and leakage of active material are prevented.
In addition, the operating temperature of this assembled battery is a high temperature of 300 to 350 ° C., and it is necessary to raise the assembled battery to this temperature, and in order to fully draw out the characteristics of each unit cell constituting the assembled battery, It is necessary to make the temperature distribution in the insulated container containing the battery uniform. For example, in Patent Document 2 and Patent Document 3, an electric heater is installed on the bottom surface and the peripheral wall surface in the heat insulating container, and the temperature in the heat insulating container is controlled by the heater.

JP 2006-48996 A JP 11-162507 A JP 2003-234132 A

The present inventors have developed an assembled battery in which a plurality of unit cells of a molten salt battery that operate at a temperature of 100 ° C. or less and have high safety during heating are connected. Such a molten salt battery is used as an electrolyte by heating a solid salt at a relatively low temperature to a molten salt at room temperature. For this reason, it is necessary to operate | move, maintaining an electrolyte in a molten state by providing a heating means and accommodating an assembled battery in a heat insulation container.
In the battery pack of this molten salt battery, the uniformity of the temperature inside each unit cell is required. If the temperature of the molten salt, which is an electrolyte, varies, the battery life decreases due to local heat storage in the molten salt at high temperatures, and the ionic conductivity decreases significantly at low temperatures, causing the battery Unevenness of internal resistance occurs, leading to deterioration of characteristics due to load distribution such as excessive current flowing only to a specific battery, and reduction of battery life.
Moreover, when using the assembled battery of a molten salt battery for the secondary battery of an electric vehicle or a hybrid vehicle, it is necessary to raise the assembled battery to the operating temperature as soon as possible. In addition, it is required to reduce the size of the entire assembled battery housed in the heat insulating container.

However, when the heating means is provided on the bottom surface and the peripheral wall surface in the heat insulating container as in the above-mentioned sodium-sulfur battery assembled battery, in order to keep the temperature inside each unit cell uniform, the heat insulating material constituting the heat insulating container is used. Since it is necessary to make it thick, there exists a problem that the magnitude | size of the whole assembled battery accommodated in the heat insulation container will enlarge.
Moreover, although the unit cell close to the heating means on the bottom surface or the peripheral wall surface can be quickly raised to the operating temperature, there is a problem that it takes time to raise the unit cell far from the heating unit to the operating temperature.

  The present invention has been made in view of such circumstances, and can keep the temperature inside each unit cell uniform and can raise the temperature of each unit cell to the operating temperature quickly. It aims at providing the assembled battery which can reduce the magnitude | size of the whole accommodated.

  An assembled battery according to the present invention is an assembled battery in which a plurality of flat-shaped unit cells are stacked in the thickness direction and accommodated in a heat insulating container and operated at a temperature higher than room temperature, and the unit cell is heated. A flat heating means is provided, and the heating means is interposed between the adjacent unit cells so that the wide surface thereof is in contact with the wide surface of the unit cell (Claim 1).

According to the present invention, since the heating means is interposed between the adjacent unit cells, the unit cells can be heated from the inside of the assembled cell. For this reason, it is easier to keep the temperature inside each unit cell uniform than in the conventional method of heating from the outside of the assembled cell, and each unit cell can be raised to the operating temperature faster. Moreover, since a heat insulation container can be made thin, the magnitude | size of the whole assembled battery accommodated in the heat insulation container can be made small.
In addition, the heat insulation container here should just be a container which equips an inside with a heat insulating material, and does not require that a container is united with a heat insulating material.

  In particular, the effect of the present invention is remarkably preferable when the unit cell is a molten salt cell using a molten salt that melts at a temperature higher than room temperature as an electrolyte (claim 2).

  Since the heating means is interposed between the adjacent unit cells, the temperature of the molten salt, which is the electrolyte of the unit cell, can be kept uniform, so that the battery life and battery characteristics can be prevented from being lowered. .

  Moreover, it is preferable that the said assembled battery is equipped with the pressurization means which pressurizes the said unit cell in the said heat insulation container in the direction which the said wide surface of the said heating means and the said wide surface of the said unit cell contact | adhere (invention). Item 3).

  Since the adhesiveness between the heating means and the unit cell is increased and the thermal conductivity from the heating unit to the unit cell is improved, the temperature inside the unit cell can be easily kept uniform. In addition, the temperature of the unit cell can be raised quickly to the operating temperature.

  The heating means is preferably interposed between the unit cells every time a plurality of the unit cells are stacked.

  If a heating means is interposed between adjacent unit cells each time the unit cells are stacked, the temperature inside each unit cell can be easily maintained, and each unit cell can be heated quickly. Since the number of heating means increases, the cost and volume of the entire assembled battery increase. Therefore, each time a plurality of unit cells are stacked, a heating means is interposed between adjacent unit cells, so that the uniformity of the internal temperature of each unit cell, the rate of temperature rise, and the entire assembled battery The balance between cost and volume can be improved.

  Further, the heating means is further installed with respect to the unit cell having a wide surface facing the inner wall surface of the heat insulating container so that the wide surface of the heating unit faces the wide surface of the unit cell. (Claim 5).

  By heating the unit cell not only from the inside of the assembled battery but also from the outside of the assembled cell, it is easy to keep the temperature inside each unit cell more uniform, and each unit cell can be operated up to the operating temperature. The temperature can be raised more quickly.

  Further, when the unit cell has a rectangular parallelepiped shape (Claim 6), the unit cell and the heating means are easily brought into close contact with each other, so that the temperature inside each unit cell can be easily maintained, and each unit cell is operated at an operating temperature. The temperature can be raised quickly. The rectangular parallelepiped shape includes a substantially rectangular parallelepiped shape.

  According to the present invention, the temperature inside each unit cell can be kept uniform, each unit cell can be quickly raised to the operating temperature, and the overall size accommodated in the heat insulating container can be reduced. can do.

It is a perspective view explaining the whole assembled battery structure concerning Embodiment 1. FIG. It is the figure which showed typically the cross section cut in the A-A 'part of FIG. It is a figure explaining the structure of the unit assembled battery used for FIG. 1 as an example of the assembled battery which concerns on Embodiment 1. FIG. It is a figure which shows the structure of the molten salt battery as an example of the unit cell used for the assembled battery which concerns on Embodiment 1, A is a top view which shows typically the internal structure of a molten salt battery, B is the longitudinal cross-sectional view. is there. It is a figure for demonstrating the 1/2 model of the assembled battery made into heating simulation object. It is a graph which shows the temperature change of each unit cell when a heating simulation is implemented using the assembled battery of 1/2 model.

Embodiment 1:
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a perspective view illustrating the overall structure of the assembled battery according to Embodiment 1. FIG. In order to explain the inside, a part is opened. FIG. 1 is a configuration example of an assembled battery in which nine unit assembled batteries each having four unit cells connected in series are connected in parallel.
In FIG. 1, nine flat unit assembled batteries 1 are stacked and accommodated in a thickness direction in a housing 2 as a heat insulating container constituting the assembled battery 10. The unit assembled battery 1 has a rectangular parallelepiped shape, and terminals for charging and discharging are formed on the side surfaces of both ends. In this example, the size of the housing 2 is 295 × 720 × 450 mm. The nine unit assembled batteries 1 are arranged in parallel, fixed to the connection terminal plates 4a and 4b by bolts 5 and electrically connected in parallel. The connection terminal plate has a structure in which an end thereof is drawn out of the housing 2, and the connection terminal plate 4a is used as a positive electrode and the connection terminal plate 4b is used as a negative electrode. Each unit assembled battery 1 is heated by a plurality of heaters 3 as heating means. The heater has a flat shape, is energized by an external wiring (not shown), and heats the assembled battery 10 so that the assembled battery 10 can be maintained at a temperature higher than room temperature. The temperature adjustment can be performed by a known control means including a temperature sensor and a control circuit.

The internal configuration will be further described with reference to FIG. FIG. 2 is a view schematically showing a cross section taken along the line AA ′ of FIG.
The inner surface of the housing 2 is covered with a heat insulating material 7 so as to keep the entire inside of the housing warm. The material of the housing | casing 2 and the heat insulating material 7 is not specifically limited, The material selected from viewpoints, such as mechanical protection of the whole assembled battery, heat insulation, can be used. For example, it is preferable that the casing 2 is made of an aluminum alloy in terms of both weight reduction and strength.

Nine unit assembled batteries 1 are arranged inside, and a plate heater as a heater 3 is arranged between every three unit assembled batteries so that the wide surface and the wide surface of the unit assembled battery are in contact with each other. Has been.
Thus, since the heater is interposed between adjacent unit assembled batteries (between adjacent unit cells), the temperature of the unit cells can be increased from the inside of the assembled battery, and is heated only from the outside of the assembled battery. As a result, the temperature inside each unit cell can be easily maintained, and each unit cell can be raised to the operating temperature quickly. Moreover, since the thickness of the heat insulating material 7 of the housing | casing 2 can be made thin, the magnitude | size of the assembled battery 10 accommodated in the housing | casing 2 can be made small.

Further, the heater 3 has the wide surface of the heater 3 facing the wide surface of the unit assembled battery 1 with respect to the unit assembled battery 1 on both ends, that is, the unit assembled battery having a wide surface facing the inner wall surface of the heat insulating material 7. It is installed to do.
Thus, by heating the unit cell from the outside of the assembled battery, the temperature inside each unit cell can be maintained more uniformly, and each unit cell can be raised to the operating temperature more quickly.

The unit assembled battery 1 and the heater 3 are pressed and urged in the stacking direction of the unit assembled battery 1 by the leaf spring 6 so as to come into close contact with each other. Here, the close contact means a state in which the surfaces are in contact with each other without a noticeable gap in a normal sense. In other words, the surfaces are in contact with each other so that the fluid does not easily flow between the surfaces. State.
Thereby, the adhesiveness between the unit assembled battery (unit cell) and the heater is increased, and the thermal conductivity from the heater to the unit assembled battery (unit cell) is improved, so that the temperature inside the unit cell can be easily kept uniform. In addition, each unit cell can be quickly heated to the operating temperature. Furthermore, there is an effect that the adhesion does not collapse even if there is vibration of the entire assembled battery or long-term deformation of the heat insulating material or the like.
In addition, if it is a pressurization means to urge | bias so that a clearance gap may not arise between each of the unit assembled battery 1 and the heater 3 which were arranged so that it might contact | adhere, it will not be limited to a leaf | plate spring.

The heater 3 is not limited to the one that is arranged between unit assembled cells (between unit cells) every time a plurality of unit assembled cells (unit cells) are stacked as in this example, and the number is also limited to this example. It is not something.
It is preferable to place a heater between the unit assembled batteries every time one unit assembled battery is stacked, from the viewpoint of uniformity of temperature and speed of temperature increase. However, since the number of heaters increases, the cost of the entire assembled battery increases. And incurs a volume increase. Therefore, in this example, each time a plurality of (for example, three) unit assembled batteries are stacked in consideration of the balance between the uniformity and temperature rise rate of the internal temperature of each unit cell and the cost and volume of the entire assembled battery. A heater is arranged between unit batteries.

  The heater 3 exemplifies a plate heater, and is not limited to this. However, if the heater 3 is flat, it is easy to be in close contact with a unit assembled battery (unit cell). In particular, the heater 3 is a plate heater. If it is, it will be easy to make it adhere more closely to a rectangular parallelepiped unit assembled battery (unit cell). Further, in order to efficiently and uniformly heat individual unit assembled batteries or individual unit cells constituting the unit batteries, the heater 3 is a plate heater having an area as large as the side surface of the unit assembled battery. Is preferred.

  The shape of the unit assembled battery 1 or the individual unit cells constituting the unit battery 1 is not limited to a rectangular parallelepiped shape, but the unit assembled battery (unit cell) and the plate heater can be easily adhered to each other by adopting a rectangular parallelepiped shape. Therefore, it is easy to keep the temperature inside each unit cell uniform, and each unit cell can be raised to the operating temperature quickly. Note that the rectangular parallelepiped shape here includes a substantially rectangular parallelepiped shape.

  Adjacent surfaces of the unit assembled battery 1 (for example, the surface 11a of the unit assembled battery 1 shown on the right in FIG. 2 and the surface 11b of the unit assembled battery 1 on the left side of the unit assembled battery 1) have no projections such as electrodes. It is easy to adhere to each other.

  The surface of the unit assembled battery 1 is preferably a metal. The surface of the unit assembled battery may be the surface of the unit cell constituting the unit assembled battery as in the example described later, or may be the surface of another case that houses the unit cell set. A metal is preferably used because of its good heat conduction. Considering weight reduction of the entire battery, aluminum or an alloy thereof is preferably used for the case. It is also preferable to use a magnesium alloy for the purpose of weight reduction.

  FIG. 3 is a longitudinal sectional view for explaining the internal structure of the unit assembled battery 1. The unit assembled battery 1 is an assembled battery in which a plurality of unit cells are electrically connected in series to increase the battery voltage. In this example, an example in which four unit cells 20 are connected as shown in FIG. 3 is shown, but the number of connections is not limited to four. For example, if the unit cell is a molten salt battery with a voltage of 3 V, the number of connections is set to four, so that the nominal voltage as a unit assembled battery is 12 V, and it can be used as a battery corresponding to an existing lead acid battery for automobiles, etc. It is preferably used because it can be easily used for a device (for example, a charger) used for the battery.

  FIG. 4 is a diagram for explaining the structure of a molten salt battery as the unit cell 20 constituting FIG. 3. FIG. 4A is a top view schematically showing the internal structure of the molten salt battery, and B is the molten salt battery. It is a longitudinal cross-sectional view which shows the structure of a battery typically.

  First, the unit cell 20 will be described with reference to FIGS. In the molten salt battery of this example, a plurality (six in the figure) of negative electrodes 21 of a rectangular flat plate and a plurality (five in the figure) of positive electrodes 41 of a rectangular flat plate respectively accommodated in a bag-like separator. They are arranged in parallel in the horizontal direction (front-rear direction in the figure) so as to alternately face each other along the vertical direction. One set of negative electrode 21, separator 31 and positive electrode 41 constitute one power generation element, and in this embodiment, five power generation elements and one other negative electrode 21 are laminated to form a battery container made of a rectangular parallelepiped aluminum alloy. Is housed inside. The battery container includes a container body 25 having an opening on the upper surface, and a rectangular flat plate-like cover body 26 that is fitted in a step formed on the inner periphery of the opening of the container body 25 to close the opening. ing. The inside of the battery container is insulated by a fluororesin coating.

  The lower end portions of the connection tabs 22 made of a rectangular aluminum alloy for taking out current are joined to the upper end portions of the negative electrodes 21 on the side close to the one side wall 25A located on the short side of the container body 25, respectively. ing. The connection tab 22 and the upper part thereof are welded to two opposing surfaces of the two arm portions 231 and 231 included in the connection member 23 having a U-shape that is open to the side wall 25B in plan view. The connection member 23 has a rectangular connection plate portion 232 whose surface direction is parallel to the arm portion 231, and an attachment hole 233 that faces the through hole 25 </ b> H formed in the side wall 25 </ b> A at the upper center of the connection plate portion 232. Is provided.

  The lower end portions of the connection tabs 42 made of a rectangular aluminum alloy for taking out current are joined to the upper end portions of the positive electrodes 41 on the side close to the other side wall 25B located on the short side of the container body 25, respectively. ing. The connection tab 42 and the upper part thereof are welded to two opposing surfaces of the two arm portions 431 and 431 included in the connection member 43 having a U-shape that is open to the side wall 25A in plan view. The connection member 43 has a rectangular connection plate portion 432 whose surface direction is parallel to the arm portion 431, and an attachment hole 433 facing the through hole 25 </ b> H provided in the side wall 25 </ b> B at the upper center of the connection plate portion 432. Is provided. In this way, the above-described five power generation elements and one negative electrode 21 are electrically connected in parallel to constitute a molten salt battery having a large battery capacity.

  The negative electrode 21 is made of an aluminum foil plated with tin, which is a negative electrode active material. Aluminum is a material suitable for the current collector of each positive / negative electrode, and has corrosion resistance against molten salt. The thickness of the negative electrode 21 including the active material is about 0.14 mm, and the dimensions in the vertical direction and the horizontal direction are 100 mm and 120 mm, respectively. The size of the container main body is vertical (height) 180 mm × horizontal (horizontal) 150 mm × thickness 35 mm.

The positive electrode 41 uses an aluminum alloy porous body as a current collector, and the current collector is filled with a mixture containing a binder, a conductive auxiliary agent, and NaCrO _{2 as a} positive electrode active material, and has a thickness of about 1 mm. It is formed. The vertical dimension and the horizontal dimension of the positive electrode 41 are smaller than the vertical and horizontal dimensions of the negative electrode 21 in order to prevent the generation of dendrites. The outer edge of the positive electrode 41 is connected to the negative electrode via the separator 31. It opposes the peripheral part of 21. FIG. The current collector of the positive electrode 41 may be a nonwoven fabric made of fibrous aluminum, for example.

  The separator 31 is made of a fluororesin film that is resistant to molten salt at a temperature at which the molten salt battery operates, and is formed so as to be porous and in a bag shape. The separator 31 is immersed together with the negative electrode 21 and the positive electrode 41 from a position of about 10 mm below the liquid level of the molten salt 30 filled in a rectangular parallelepiped battery container. Thereby, a slight drop in the liquid level is allowed.

  Each of the connection members 23 and 43 serves as an external electrode for connecting the negative electrode 21 and the positive electrode 41 to an external electric circuit, and is located above the liquid surface of the molten salt 30. . The molten salt 30 is composed of an FSI (bisfluorosulfonylimide) or TFSI (bistrifluoromethylsulfonylimide) anion and a cation of sodium and / or potassium, but is not limited thereto.

  In the above-described configuration, by heating the entire battery container to 85 ° C. to 95 ° C. using the heater 3 described above, the molten salt 30 is melted and can be charged and discharged via the connecting members 23 and 43. Become.

  Hereinafter, the unit assembled battery 1 will be described with reference to FIGS. 3 and 4. Four molten salt batteries as the unit cells 20 are arranged so that the side walls on the short side of the adjacent container bodies 25 are in close contact with each other. In each container body 25, the five power generating elements (the negative electrode 21, the positive electrode 41 wrapped in the separator 31) and one negative electrode 21 and the molten salt 30 connected in parallel by the connecting members 23 and 43 are incorporated. Yes. A through-hole 25H penetrating in the lateral direction is provided in the upper center of the adhered side wall, and an insulating bushing (bearing cylinder) made of Teflon (registered trademark) or the like is opened in the through-hole 25H. A bolt 51 made of an aluminum alloy is inserted. The bolt 51 is fastened by a nut 52 made of aluminum alloy, and the unit cell 20 is fixed and electrically connected in series.

  Next, the conductive material used for the molten salt battery will be described. When a metal (conductive material) having a different ionization tendency is placed at a site in contact with the electrolyte, such as the molten salt 30, electric corrosion occurs due to current flowing from one metal to the other. For this reason, in this embodiment, as described above, the connection tabs 22 and 42, the connection members 23 and 43, the bolt 51 and the nut 52 are made of the same conductive material as the negative electrode 21 and the positive electrode 41 (in this embodiment, aluminum). Alloy) and the occurrence of electrolytic corrosion is prevented. As described above, the battery container is also made of an aluminum alloy.

As described above, the unit cells 20 are arranged so that the side surfaces of the battery containers are in close contact with each other to form the unit assembled battery 1, and the unit assembled cells 1 have the side surfaces of the unit cell 20 as a component. The entire battery pack 10 is arranged so as to be in close contact with each other.
The battery pack 10 of the molten salt battery is required to have a uniform temperature inside each unit cell 20. If the temperature of the molten salt, which is an electrolyte, varies, the battery life decreases due to local heat storage in the molten salt at high temperatures, and the ionic conductivity decreases significantly at low temperatures, causing the battery Unevenness of internal resistance occurs, leading to deterioration of characteristics due to load distribution such as excessive current flowing only to a specific battery, and reduction of battery life.
Moreover, when using the assembled battery 10 of a molten salt battery for a secondary battery of an electric vehicle or a hybrid vehicle, it is necessary to raise the temperature of the assembled battery to the operating temperature as soon as possible. In addition, it is required to reduce the size of the entire assembled battery housed in the heat insulating container.
Therefore, in the battery pack 10 of the molten salt battery according to the first embodiment, the adjacent unit assembled batteries 1 (elements) are arranged so that the heater 3 is in contact with the wide surface of the unit assembled battery 1 (unit cell 20). Interposed between the batteries 20).
Thereby, the temperature of the unit cell 20 can be raised from the inside of the assembled battery 10, and it is easier to keep the temperature inside each unit cell 20 uniform than when heating only from the outside of the assembled cell 10. 20 can be quickly raised to the operating temperature, and the battery life and battery characteristics of the battery pack 10 of the molten salt battery can be prevented from being lowered.

The inventors conducted a heating simulation for the assembled battery 10 described above. The details of the assembled battery 10 subjected to the heating simulation are as follows.
First, the housing 2 is made of aluminum, and the heat insulating material 7 of the housing 2 has a thickness of 50 mm.
For the unit cell 20, the container body 25 is made of aluminum, and the size thereof is set in the vertical direction (height) 150 mm × the horizontal direction (horizontal width) 130 mm × thickness 36 mm. The molten salt 30 was poured into the container body 25 of the unit cell 20 so that the liquid level was 110 mm from the bottom surface of the container body 25 of the unit cell 20.
About the heater 3, the magnitude | size was made into the vertical direction (height) 100mm x horizontal direction (horizontal width) 260mm, and it was made for the horizontal width to correspond to the horizontal width of the two container main bodies 25 of the unit cell 20. FIG. Further, the lower end of the heater 3 is placed at the container body 25 of the unit cell 20 so that the center in the vertical direction of the heater 3 coincides with the center of the unit body 25 of the unit cell 20 filled with the molten salt 30. It arrange | positioned so that it might become a position of 5 mm from the bottom. The ambient environment temperature was 25 ° C., and the temperature of the heater 3 was 100 ° C.
For simplicity, it is assumed that the heater 3 is not thick and there is no gap between the heat insulating material 7 and the unit cell 20 (the assembled battery 10).

FIG. 5 is a diagram for explaining a half model of the assembled battery as a heating simulation target. FIG. 5 is a view of the cross section at the center in the longitudinal direction (height direction) of the assembled battery 10 as viewed from above, and the right half surrounded by the thick line of the assembled battery 10 is the subject of the heating simulation.
The half model of the assembled battery 10 includes 18 unit cells 20, and numbers 20-1 to 20-18 are assigned to the unit cells 20 as shown in FIG. 5.
The heater 3 is provided between the unit cell 20-1 and the heat insulating material 7, between the unit cell 20-10 and the heat insulating material 7, between the unit cell 20-3 and the unit cell 20-4, and between the unit cell 20-12 and the unit cell. 20-13, between unit cell 20-6 and unit cell 20-7, between unit cell 20-15 and unit cell 20-16, between unit cell 20-9 and heat insulating material 7, between unit cell 20- 18 and the heat insulating material 7.

FIG. 6 is a graph showing a temperature change of each unit cell when a heating simulation is performed using a battery model of 1/2 model. In FIG. 6, a curve A indicates a unit cell 20 (unit cell 20-1, 20-3, 20-4, 20-6, 20-7, 20-9) adjacent to the heater 3 among 18 unit cells. , 20-10, 20-12, 20-13, 20-15, 20-16, 20-18), and curve B indicates a unit cell 20 (unit cell not adjacent to the heater 3). 20-2, 20-5, 20-8, 20-11, 20-14, 20-17).
From FIG. 6, the unit cell 20 adjacent to the heater 3 has reached 85 ° C., which is the operating temperature of the molten salt battery, in about 10 minutes, and the unit cell 20 not adjacent to the heater 3 is about 90 ° C. It has been reached in 13 minutes, and it can be seen that all the unit cells reached the operating temperature of the molten salt battery early.
As described above, by arranging the heater 3 between the unit cells 20 every time three unit cells 20 are stacked, each unit cell is suppressed from increasing in cost and volume. The battery 20 can be quickly heated up to the operating temperature of the assembled battery 10.

The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.
For example, in the above-described embodiment, the unit cell is configured with a container made of a rectangular parallelepiped aluminum alloy, but is not limited thereto, and is a container made of a flat bag-like laminate film. The structure formed by may be sufficient.

DESCRIPTION OF SYMBOLS 1 Unit assembled battery 2 Housing | casing 3 Heater 4a, 4b Connection terminal board 5 Bolt 6 Leaf spring 7 Heat insulating material 10 Assembly battery 11a, 11b Surface 20 Unit cell 21 Negative electrode 22, 42 Connection tab 23, 43 Connection member 231, 431 Arm 232, 432 Connecting plate portion 233, 433 Mounting hole 25 Container body 25A, 25B Side wall 25H Through hole 26 Cover body 30 Molten salt 31 Separator 41 Positive electrode 51 Bolt 52 Nut

Claims (6)

A plurality of flat-shaped unit cells are stacked in the thickness direction and accommodated in a heat insulating container, and are operated at a temperature higher than room temperature,
A flat heating means for heating the unit cell;
The heating means is interposed between the adjacent unit cells so that the wide surface is in contact with the wide surface of the unit cell,
Assembled battery. The unit cell is a molten salt battery using, as an electrolyte, a molten salt that melts at a temperature higher than room temperature.
The assembled battery according to claim 1. A pressure means for pressurizing the unit cell in a direction in which the wide surface of the heating unit and the wide surface of the unit cell are in close contact with each other;
The assembled battery according to claim 1 or 2. The heating means is interposed between the unit cells every time a plurality of the unit cells are stacked.
The assembled battery according to any one of claims 1 to 3. The heating means is further installed with respect to the unit cell having a wide surface facing the inner wall surface of the heat insulating container so that the wide surface of the heating unit faces the wide surface of the unit cell.
The assembled battery according to any one of claims 1 to 4. The unit cell has a rectangular parallelepiped shape.
The assembled battery according to any one of claims 1 to 5.

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