JP2008300103A - Power storage module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To appropriately control temperature of a power storage module in a simple structure. <P>SOLUTION: The power storage module 10 is structured of storage cells laminated with given intervals. Cooling flow channels 15 are zoned among the storage cells 13, and each storage cell 13 is provided with a switching member 22 along the cooling flow channel 15. The switching member 22 is formed of a two-way shape memory alloy, deformed into a flat shape in case a temperature rises above 0°C, and a bent shape in case it is below 0°C. With this, when the cell temperature rises, the switching member 22 can be deformed so as to open the cooling flow channel 15, and the storage cell 13 can be cooled with cooling wind introduced into the cooling flow channel 15. On the other hand, when the cell temperature falls, the switching member 22 can be deformed to close the cooling flow channel 15, and the cooling flow channel 15 closed can be utilized as a heat-retaining layer. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a power storage module including a plurality of power storage cells stacked at predetermined intervals.

In recent years, an electric vehicle in which only an electric motor is mounted as a power source and a hybrid vehicle in which an engine and an electric motor are mounted as power sources have been developed. Electric vehicles and hybrid vehicles are equipped with power storage modules such as batteries and capacitors, and electric power is supplied from these power storage modules to the electric motor. In addition, the temperature of the power storage module rises with charging / discharging. If left unattended, the performance and performance of the power storage module will be reduced, so it is important to actively cool the power storage module. It has become. Therefore, a cooling system has been proposed in which a cooling flow path is formed in the power storage module and a cooling fan is provided so that cooling air flows through the cooling flow path to lower the temperature of the power storage module (for example, Patent Documents). 1 and 2).
JP 2006-278327 A JP 2006-318820 A

  By the way, in order to fully exhibit the performance of the power storage module, it is important not only to avoid the high temperature state of the power storage module but also to ensure the output performance by avoiding the low temperature state of the power storage module. However, since the power storage modules described in Patent Documents 1 and 2 have a structure that focuses only on cooling of the power storage module, it has been impossible to cope with overcooling of the power storage module in a low temperature environment. . In addition, in order to raise the temperature of the power storage module in a low temperature environment, it is conceivable to assemble a heating heater to the power storage module. However, installing a heating heater and controlling it will complicate the structure of the power storage module. In addition to inviting, it has become a factor that leads to the complexity of the control system.

  An object of the present invention is to appropriately control the temperature of a power storage module with a simple configuration.

  The power storage module of the present invention is a power storage module including a plurality of power storage cells stacked at a predetermined interval, and is disposed in a flow path partitioned between the power storage cells, and when the temperature exceeds a predetermined temperature, It has a shape that opens and closes the flow path, and has an opening and closing member that deforms into a shape that closes the flow path when the temperature falls below a predetermined temperature.

  The power storage module of the present invention is characterized in that the opening / closing member is a shape memory alloy or a bimetal.

  The power storage module of the present invention is characterized in that the opening / closing member is attached to the power storage cell.

  The power storage module of the present invention is characterized in that an outer container of the power storage cell is a laminate film or a rectangular outer case.

  The power storage module of the present invention is characterized in that the power storage cell is a lithium ion capacitor.

  In the power storage module of the present invention, the power storage cell is a lithium ion secondary battery.

  In the electricity storage module of the present invention, the positive electrode active material of the electricity storage cell includes vanadium oxide including layered crystal grains having a layer length of 1 nm to 30 nm.

  In the power storage module of the present invention, the power storage cell includes a lithium ion supply source, and at least one of a positive electrode and a negative electrode is preliminarily doped from the lithium ion supply source.

  According to the present invention, an opening / closing member is provided that deforms to open the flow path when the temperature exceeds the predetermined temperature, and closes the flow path when the temperature falls below the predetermined temperature. The path can be opened to cool the storage cell, and when the cell temperature decreases, the channel can be closed to keep the storage cell warm. Thereby, it becomes possible to control an electrical storage cell to an appropriate temperature range with a simple configuration.

  FIG. 1 is a perspective view showing a power storage module 10 according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view schematically showing the structure of the power storage module 10 along the line AA in FIG. As shown in FIGS. 1 and 2, the power storage module 10 includes a housing 11 in which an intake opening 11a and an exhaust opening 11b are formed. In the housing 11, a plurality of cell cases 12 are stacked at a predetermined interval, and each cell case 12 accommodates a storage cell 13. Further, a cooling fan 14 is attached to the housing 11 in order to cool the storage cell 13 that generates heat along with charge / discharge. The cooling air generated by the cooling fan 14 is introduced into the housing 11 from the intake opening 11a, flows through the cooling flow path (flow path) 15 partitioned between the storage cells 13, and then flows from the exhaust opening 11b to the outside. It is supposed to be discharged.

  FIG. 3 is a perspective view schematically showing the storage cell 13 housed in the cell case 12. As shown in FIG. 3, the power storage cell 13 is a laminate-type power storage cell formed in a flat plate shape, and a laminate film 20 is employed as an outer container of the power storage cell 13. In the laminate film 20 that has been subjected to deep drawing, an electrode laminate unit and an electrolytic solution described later are accommodated, and the outer peripheral portion of the laminate film 20 is sealed by thermal welding or the like. Such a storage cell 13 is held between the split cell cases 12 and is housed in the housing 11 in a state where the cell cases 12 are stacked. In addition, as shown in FIG. 2, the cell case 12 is formed with a boss portion 21 for setting a clearance, and a cooling flow path 15 is defined between the storage cells 13 facing each other at the time of stacking. Yes. A plurality of openings (not shown) are formed in the cell case 12 in order to expose the surface of the storage cell 13 to the cooling flow path 15.

  4 is a side view schematically showing the structure of the storage cell 13 from the direction of arrow A in FIG. As shown in FIGS. 3 and 4, a plate-shaped opening / closing member 22 is attached to the edge of the laminate film 20 constituting the outer container of the storage cell 13 so as to be sandwiched from the front side and the back side. The opening / closing member 22 was heat-treated so that the intermediate temperature ((As + Af) / 2) between the martensite reverse transformation start temperature (As) and the martensite reverse transformation end temperature (Af) was 0 ° C. 81.8 % Cu-14.2% Al-4.0% Ni shape memory alloy, and as shown in FIG. 4, when the temperature of the opening / closing member 22 rises to 0 ° C. or higher, a flat plate shape On the other hand, when the temperature of the opening / closing member 22 drops below 0 ° C., it is designed to bend at about 30 °. In other words, the illustrated opening / closing member 22 is formed using a bi-directional shape memory alloy that memorizes both the shape at high temperature and the shape at low temperature.

  It should be noted that the heat treatment and the composition were controlled so that a value of (As + Af) / 2 was taken around 0 ° C. even in the composition other than 81.8% Cu-14.2% Al-4.0% Ni used this time. It is also possible to use a directional shape memory alloy. Further, by using a combination of the opening / closing member 22 and a spring member, the shape of the high temperature side or the low temperature side is memorized, and a unidirectional shape memory alloy controlled so as to be deformed in the same temperature range is used. Thus, the opening / closing member 22 may be formed. Furthermore, it is also possible to use a low-temperature bimetal having a proportional temperature range around 0 ° C., such as JIS · C2530 · TM1 (proportional temperature range −20 to 150 ° C.).

  Next, the operating state of the opening / closing member 22 provided in the storage cell 13 will be described. FIGS. 5A and 5B are explanatory views showing the operating state of the opening / closing member 22. As shown in FIG. 5 (A), when the temperature of the opening / closing member 22 is 0 ° C. or higher, the opening / closing member 22 is deformed into a flat plate shape so as to open the cooling passage 15. The storage cell 13 can be cooled by guiding the wind. Thereby, the high temperature state of the electricity storage cell 13 can be avoided, and the deterioration of the electricity storage module 10 can be suppressed and the performance can be stabilized. On the other hand, as shown in FIG. 5B, when the temperature of the opening / closing member 22 is less than 0 ° C., the opening / closing member 22 is deformed into a curved shape so as to close the cooling flow path 15, so that the blocked cooling The flow path 15 can be used as a heat insulating layer. Thereby, the low temperature state of the electricity storage cell 13 can be eliminated at an early stage by using the heat generated by the electricity storage cell 13 due to charging / discharging, and the output characteristics of the electricity storage module 10 can be improved early in a low temperature environment. .

  Here, FIG. 6 is a cross-sectional view schematically showing the structure of a power storage module 30 as a comparative example that does not include the opening / closing member 22, and FIG. 7 shows the power storage of the present invention when a discharge test is performed in a low temperature environment. It is a diagram which shows the cell temperature change of the module 10 and the electrical storage module 30 of a comparative example. In addition, as conditions for the discharge test, the outside air temperature is −30 ° C., the voltage is 150 V, the current is 4 A, the discharge time is 800 seconds, and the cooling fan 14 is stopped. Further, the power storage module 10 of the present invention used in the discharge test and the power storage module 30 of the comparative example are structurally different only in the presence or absence of the opening / closing member 22.

  First, as shown in FIG. 6, in the power storage module 30 of the comparative example that does not include the opening / closing member 22, heat easily escapes from the power storage cell 13 to the cooling channel 15 that is always open. It is difficult to raise the cell temperature due to self-heating of the storage cell 13. As shown in FIG. 7, in the power storage module 30 of the comparative example, even when a discharge test is performed over 800 seconds due to heat radiation from the power storage cell 13 to the cooling flow path 15, the cell temperature is It was confirmed that it rose only to about -20 ° C.

  On the other hand, in the electricity storage module 10 of the present invention having the opening / closing member 22, when the temperature falls below 0 ° C., the cooling channel 15 is blocked by the opening / closing member 22 as shown in FIG. Therefore, an air insulation layer is formed between the storage cells 13. Thus, by covering the energy storage cell 13 with the heat retaining layer, it becomes difficult for heat to escape from the energy storage cell 13, so that it is easy to raise the cell temperature by self-heating of the energy storage cell 13. As shown in FIG. 7, in the power storage module 10 of the present invention, it is confirmed that the cell temperature reaches 0 ° C. in about 500 seconds from the start of the discharge test due to the heat retention effect of the power storage cell 13 by the heat retention layer. It was done. When the cell temperature exceeds 0 ° C., the cooling channel 15 is opened by the opening / closing member 22 as shown in FIG. Since heat can be released from the cell 13, it was confirmed that an excessive increase in the cell temperature was suppressed as shown in FIG.

  As described above, by providing the open / close member 22 for the storage cell 13, the open / close state of the cooling flow path 15 can be controlled according to the cell temperature. When the temperature is high, the cell temperature can be lowered. In addition, by forming the opening / closing member 22 using a shape memory alloy, it is possible to automatically control the opening / closing state of the cooling flow path 15 in accordance with a temperature change. As described above, since the temperature of the power storage cell 13 can be adjusted with a simple configuration, it is possible to achieve high performance and long life of the power storage module 10 at low cost.

  In the above description, the opening / closing member 22 is formed using a shape memory alloy. However, the present invention is not limited to this, and a bimetal obtained by bonding two metal plates having different thermal expansion coefficients is used. Thus, the opening / closing member 22 may be formed. Even when bimetal is used, the degree of bending of the opening / closing member 22 can be changed according to the temperature. Therefore, the opening / closing member 22 is deformed so as to close the cooling channel 15 at low temperatures, and the cooling channel at high temperatures. The opening / closing member 22 can be deformed so as to open 15.

  In the above description, the opening / closing member 22 is deformed so as to open the cooling flow path 15 by exceeding the predetermined temperature of 0 ° C., while the cooling flow path 15 is controlled by falling below the predetermined temperature of 0 ° C. Although the opening / closing member 22 is deformed so as to be closed, the present invention is not limited to this, and the predetermined temperature when the opening / closing member 22 is deformed may be appropriately changed. Further, in the case shown in the figure, the open / close state of the cooling flow path 15 is controlled by a pair of opening / closing members 22 facing each other via the cooling flow path 15. The opening / closing state of the cooling flow path 15 may be controlled by 22.

  In the illustrated case, the opening / closing member 22 is attached to the laminate film 20 of the storage cell 13. However, the present invention is not limited to this, and the opening / closing member 22 is attached to the cell case 12. Also good. Furthermore, although the laminate film 20 is employed as the exterior container of the storage cell 13, the present invention is not limited to this, and a rectangular exterior case (metal case or the like) may be employed as the exterior container.

  It goes without saying that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. For example, the cooling air is generated by driving the cooling fan 14, but the amount of cooling air generated is changed by controlling the driving state according to the cell temperature without always driving the cooling fan 14. You may make it let it. Further, the cooling fan 14 may be removed from the power storage module 10 as long as the cooling performance is ensured by the introduction of traveling wind or the like. Furthermore, the power storage module 10 of the present invention can be suitably used as a power source for electric vehicles, hybrid vehicles, and the like.

  The configuration of the power storage module 10 of the present invention can be applied to power storage modules including various types of battery cells and capacitor cells. Here, FIG. 8 is a cross-sectional view schematically showing the internal structure of the storage cell 13, and FIG. 9 is a cross-sectional view showing the internal structure of the storage cell 13 partially enlarged. As shown in FIG. 8, an electrode lamination unit 40 is disposed inside the laminate film 20 included in the storage cell 13, and the electrode lamination unit 40 is composed of positive electrodes 42 and negative electrodes 43 that are alternately laminated via separators 41. And is composed of. Further, a lithium electrode 44 is disposed on the outermost part of the electrode laminate unit 40 so as to face the negative electrode 43, and the electrode laminate unit 40 and the lithium electrode 44 constitute a three-electrode laminate unit 45. Note that an electrolyte solution made of an aprotic organic solvent containing a lithium salt is injected into the laminate film 20.

  Subsequently, as shown in FIG. 9, the positive electrode 42 includes a positive electrode current collector 42b having a large number of through holes 42a, and a positive electrode mixture layer 42c applied to the positive electrode current collector 42b. The negative electrode 43 includes a negative electrode current collector 43b having a large number of through holes 43a and a negative electrode mixture layer 43c applied to the negative electrode current collector 43b. A plurality of positive electrode current collectors 42b connected to each other are connected to positive electrode terminals 46 projecting from the laminate film 20 to the outside, and a plurality of negative electrode current collectors 43b connected to each other are connected to the laminate film 20 A negative electrode terminal 47 protruding from the outside is connected. Further, the lithium electrode 44 disposed at the outermost part of the electrode stack unit 40 includes a lithium electrode current collector 44a made of a conductive porous material such as a stainless mesh, and metal lithium (lithium ion supply source) 44b attached thereto. The lithium electrode current collector 44a is connected to the negative electrode current collector 43b.

  The positive electrode mixture layer 42 c of the positive electrode 42 contains vanadium oxide as a positive electrode active material capable of reversibly doping and dedoping lithium ions, and the negative electrode mixture layer 43 c of the negative electrode 43 includes Contains natural graphite as a negative electrode active material capable of reversibly doping and dedoping lithium ions. Further, the negative electrode mixture layer 43 c of the negative electrode 43 is doped in advance with lithium ions from the metal lithium 44 b, thereby reducing the electrode potential of the negative electrode 43 and improving the energy density of the storage cell 13. The positive electrode 42 may be pre-doped with lithium ions, and both the positive electrode 42 and the negative electrode 43 may be pre-doped with lithium ions. In addition, doping (doping) means occlusion, support, adsorption, insertion, and the like, and means a state in which lithium ions, anions, and the like enter the positive electrode active material and the negative electrode active material. De-doping (de-doping) means release, desorption, and the like, and means a state in which lithium ions, anions, and the like are emitted from the positive electrode active material and the negative electrode active material.

By the way, the vanadium oxide as the positive electrode active material described above is a layered crystalline material having a layered structure. For example, vanadium pentoxide (V ₂ O ₅ ) has 2 pentahedral units each containing VO ₅ as one unit. One layer is formed by spreading by a covalent bond in the dimension direction. By laminating these layers, it has a layered structure as a whole. While maintaining such a layered crystal structure, the vanadium oxide is made macroscopically amorphous to form fine layered crystal grains. The state of such a layered crystalline material is that only a crystal structure with a layer length of 30 nm or less, or a crystal structure in such a state and an amorphous structure coexist from a microscopic viewpoint that enables observation of the order of nm or less. Is confirmed. However, when such a state is viewed from a macro viewpoint where only observation of μm order larger than nm can be performed, an amorphous structure in which the crystal structure is irregularly arranged is observed.

  Here, FIG. 10 is a schematic diagram showing a layered crystal structure with a short layer length, and FIG. 11 is a schematic diagram showing a layered crystal structure with a long layer length. As shown in FIG. 10, in the partially amorphized vanadium oxide, a layered crystal structure (so-called short period structure) having a short layer length L1 is formed. On the other hand, in the case shown in FIG. 11, a layered crystal structure (so-called long-period structure) having a long layer length L2 is formed. When a layered crystal structure having a short layer length as shown in FIG. 10 is applied to the electrode active material, ions easily enter and exit between layers of the layered crystal structure, so that charge / discharge characteristics, cycle characteristics, and the like can be improved. .

  The minimum layer length of the layered crystal structure may be 1 nm or more. This layered crystal state is because lithium ions cannot be doped / dedoped and the high capacity cannot be taken out if the layer length of the layered crystal is less than 1 nm from the viewpoint of the entry and exit of lithium ions between layers. On the contrary, if the layer length exceeds 30 nm, the crystal structure collapses due to charge / discharge, and the cycle characteristics deteriorate. Therefore, the layer length is desirably 1 nm or more and 30 nm or less. More preferably, the layer length may be 5 nm or more and 25 nm or less.

In this way, vanadium oxide was used as the positive electrode active material, natural graphite was used as the negative electrode active material, and a current collector foil (current collector) having through holes was used, and lithium ions were previously doped with lithium ions. Although an ion secondary battery is shown, the present invention is not limited to this, and the present invention can be effectively applied to a battery using other positive electrode active materials and negative electrode active materials. For example, as the positive electrode active material, lithium cobaltate (LiCoO ₂ ), lithium nickelate (LiNiO ₂ ), lithium manganate (LiMnO ₂ ), and composite oxides thereof (LiCo _x Ni _y Mn _z O ₂ , x + y + z = 1) , Lithium manganate spinel (LiMn ₂ O ₄ ), lithium vanadium oxide, olivine-type LiMPO ₄ (M: Co, Ni, Mn, Fe, etc.), M _x O _y (MnO ₄ , Fe ₂ O ₃ etc.) As a negative electrode active material, a carbon material made of graphitizable carbon material, graphite, or the like, or a non-carbon material made of silicon, tin, or the like, and a current collector foil (current collector) having no through holes are used. A lithium ion secondary battery having a general configuration in which lithium ions are not doped in advance and using a non-aqueous organic solvent solution containing a lithium salt as an electrolyte. It is possible to effectively apply the present invention with respect to the stored module had.

  In addition, activated carbon is used as the positive electrode active material, carbon materials such as graphite, hard carbon, coke and the like that can reversibly carry lithium ions as the negative electrode active material, and polyacene-based material (PAS) are used, and lithium salt is used as the electrolyte. The present invention can also be effectively applied to a power storage module using a lithium ion capacitor that uses a non-aqueous organic solvent solution. In the lithium ion capacitor, from the viewpoint of increasing the capacity, it is possible to dope lithium ions into the negative electrode active material so that the positive electrode potential becomes 2.0 V after the positive electrode and the negative electrode are short-circuited. desirable.

It is a perspective view which shows the electrical storage module which is one embodiment of this invention. It is sectional drawing which shows schematically the structure of an electrical storage module along the AA line of FIG. It is a perspective view which shows roughly the electrical storage cell accommodated in a cell case. It is a side view which shows roughly the structure of an electrical storage cell from the arrow A direction of FIG. (A) And (B) is explanatory drawing which shows the operating state of an opening-and-closing member. It is sectional drawing which shows schematically the structure of the conventional electrical storage module which is not provided with the opening / closing member. It is a diagram which shows the cell temperature change of the electrical storage module of this invention when the discharge test is performed in a low temperature environment, and the conventional electrical storage module. It is sectional drawing which shows the internal structure of an electrical storage cell roughly. It is sectional drawing which expands and shows the internal structure of an electrical storage cell partially. It is a schematic diagram which shows a layered crystal structure with a short layer length. It is a schematic diagram which shows a layered crystal structure with a long layer length.

Explanation of symbols

10 power storage module 13 power storage cell 15 cooling flow path (flow path)
20 Laminate film (exterior container)
22 Opening / closing member 42 Positive electrode 43 Negative electrode 44b Metal lithium (lithium ion supply source)

Claims (8)

A power storage module comprising a plurality of power storage cells stacked at a predetermined interval,
An opening / closing member that is disposed in a flow path defined between the storage cells and deforms into a shape that opens the flow path when the temperature exceeds a predetermined temperature, and deforms into a shape that closes the flow path when the temperature is lower than a predetermined temperature. A power storage module comprising: The power storage module according to claim 1,
The power storage module, wherein the opening / closing member is a shape memory alloy or a bimetal. The power storage module according to claim 1 or 2,
The power storage module, wherein the opening / closing member is attached to the power storage cell. In the electrical storage module of any one of Claims 1-3,
The power storage module according to claim 1, wherein the outer packaging container of the power storage cell is a laminate film or a rectangular outer case. In the electrical storage module of any one of Claims 1-4,
The power storage module is a lithium ion capacitor. In the electrical storage module of any one of Claims 1-4,
The power storage module is a lithium ion secondary battery. The power storage module according to claim 6, wherein
The positive electrode active material of the said electrical storage cell contains vanadium oxide provided with the layer crystal grain whose layer length is 1 nm or more and 30 nm or less. In the electrical storage module of any one of Claims 1-7,
The power storage module includes a lithium ion supply source, and at least one of a positive electrode and a negative electrode is preliminarily doped with lithium ions from the lithium ion supply source.

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