JP2013069558A - Battery module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery module which includes unit cells and suppresses deterioration in electrical characteristics.SOLUTION: The battery module comprises: unit cells (22) having terminals (22a, 22b) protruding from a case; and a sealed container (24) for housing the unit cells (22). The sealed container (24) is filled with a pressurized gas. The unit cells (22) are housed in the sealed container (24) so that the terminals (22a, 22b) are arranged in a lower part of the case.

Description

  The present invention relates to a battery module.

  In the prior art, a battery module in which a single cell is accommodated in a container is known. When a battery module has a plurality of single cells, it is known that a plurality of single cells are arranged and accommodated inside a container.

  In Japanese Patent Application Laid-Open No. 2003-187857, a power generation unit housed in a battery exterior formed of a composite laminate film has the same width as a positive electrode current collector and a negative electrode current collector of the power generation unit, and has a rectangular shape. A battery including a positive terminal electrode and a negative terminal electrode protruding from different sides of the battery exterior is disclosed. In this battery, it is disclosed that the positive electrode current collector and the negative electrode current collector are directly projected from the battery exterior in a state in which the respective ends of the positive electrode current collector and the negative electrode current collector are laminated to form a positive electrode terminal electrode and a negative electrode terminal electrode. In this battery, it is disclosed that a positive electrode terminal electrode and a negative electrode terminal electrode protrude in a lateral direction, and a plurality of batteries are accommodated in an external container.

  In Japanese Patent Laid-Open No. 2003-229117, a flat battery in which a positive electrode terminal and a negative electrode terminal are separated from each other and led to an outer peripheral edge portion, and a width of an active material region and a predetermined electrode terminal width have a predetermined relationship. Is disclosed.

JP 2003-187857 A JP 2003-229117 A JP 2010-262792 A

  Some rechargeable batteries that can be charged and discharged gradually deteriorate in electrical characteristics as the charging and discharging electric operations are performed. For example, in the case of a lithium ion battery including a positive electrode active material and a negative electrode active material, the active material expands or contracts with insertion or extraction of lithium ions. For example, many active materials have a characteristic of expanding when lithium ions are occluded and contracting when lithium ions are released.

  When charging and discharging are repeated and the active material repeats expansion and contraction, there arises a problem that the positive electrode or the negative electrode containing the active material is cracked or the positive electrode or the negative electrode is peeled off from the adjacent current collector. Further, in an all-solid battery in which the electrolyte layer disposed between the positive electrode and the negative electrode is solid, there arises a problem that the contact resistance at the interface between the positive electrode or the negative electrode and the electrolyte layer increases. As a result, cycle characteristics and other electrical characteristics are deteriorated. For example, there arises a problem that the battery capacity decreases when charging and discharging are repeated.

  Moreover, it is preferable that the temperature around the unit cell is uniform throughout the battery module usage period. That is, it is preferable that the temperature around a part of the unit cell is high and no temperature gradient is generated inside the unit cell. When the temperature gradient is generated in the single cell, the deterioration partially proceeds, and the electric characteristics of the single cell are deteriorated or the life is shortened. For example, when charging and discharging are repeated, there arises a problem that cycle characteristics deteriorate.

  An object of this invention is to provide the battery module which contains a cell and suppresses the deterioration of an electrical property.

  The battery module of the present invention includes a cell having a case and a terminal protruding from the case, and a sealed container that houses the cell and can be sealed. The sealed container is filled with a pressurized fluid with the inside sealed. The unit cell is accommodated in a hermetically sealed container so that the terminal is disposed at the lower part of the case.

  In the above-mentioned invention, a plurality of single cells housed in the sealed container are provided, the plurality of single cells are arranged apart from each other, and a flow path through which a fluid flows is formed between the single cells. It is preferable that a gap is formed between the battery and the wall surface of the sealed container, and a flow path through which a fluid flows is formed between the unit cell and the wall surface of the sealed container.

  In the above invention, the single battery can include an all-solid battery having a solid positive electrode layer, a solid electrolyte layer, and a solid negative electrode layer.

  ADVANTAGE OF THE INVENTION According to this invention, the battery module which contains a single battery and suppresses the deterioration of an electrical property can be provided.

It is a general | schematic disassembled perspective view of the battery module in embodiment. It is a schematic perspective view of the cell in embodiment. It is an expansion schematic sectional drawing inside the single cell in embodiment. It is a schematic sectional drawing when the battery module in an embodiment is cut in the direction in which single cells are arranged. It is a schematic perspective view of the part which has performed positioning of the cell in an embodiment. It is a schematic sectional drawing when the battery module in an embodiment is cut in a direction perpendicular to the direction in which single cells are arranged.

  The battery module in the embodiment will be described with reference to FIGS. The battery module in the present embodiment is disposed in a drive device such as a hybrid vehicle or an electric vehicle.

  FIG. 1 shows a schematic exploded perspective view of the battery module in the present embodiment. The battery module in the present embodiment is a power storage device that stores electricity, and includes a single battery 22 as a battery cell. In the present embodiment, a plurality of unit cells 22 are arranged side by side. The battery module in the present embodiment includes an airtight container 24 as a container for accommodating the unit cell 22 therein. A plurality of unit cells 22 are accommodated in the sealed container 24. The sealed container 24 is formed so that the internal space can be sealed.

  The sealed container 24 in the present embodiment includes a base material 24a and a lid member 24b. The lid member 24b is formed so as to cover the plurality of single cells 22. A seal member for suppressing gas leakage is disposed between the base material 24a and the lid member 24b. As shown by the arrow 52, the lid member 24b is fixed to the base material 24a, whereby the inside of the sealed container 24 is sealed.

  The sealed container 24 is filled with a pressurized fluid. In the present embodiment, a pressurized gas is filled. For example, the gas is filled at a pressure larger than atmospheric pressure. As the gas filled in the sealed container 24, any gas such as an inert gas can be employed.

  FIG. 2 shows a schematic perspective view of the unit cell in the present embodiment. The unit cell 22 in the present embodiment is formed in a rectangular parallelepiped shape. The unit cell 22 includes a case 22c and terminals 22a and 22b protruding from the case 22c. The terminals 22a and 22b are parts that conduct electricity. The terminals 22a and 22b in the present embodiment are formed so as to protrude in one direction. In the example shown in FIG. 2, the terminal 22a is a positive electrode and the terminal 22b is a negative electrode.

  Case 22c of unit cell 22 in the present embodiment is formed of a material that can be deformed by applying pressure from the outside. The case 22c can be formed of, for example, a laminate film. The case 22c is not limited to this form, and may be any shape that can be deformed when pressure is applied from the outside. Moreover, although the unit cell in this Embodiment is a rectangular parallelepiped, it is not restricted to this form, Arbitrary shapes can be employ | adopted.

  FIG. 3 shows an enlarged schematic cross-sectional view of the inside of the unit cell in the present embodiment. The unit cell 22 in the present embodiment is a lithium ion battery. The unit cell 22 in the present embodiment is an all solid state battery. The unit cell 22 in the present embodiment has a positive electrode layer 30, a negative electrode layer 31, and an electrolyte layer 32 interposed between the positive electrode layer 30 and the negative electrode layer 31. A laminate of the positive electrode layer 30, the negative electrode layer 31, and the electrolyte layer 32 is laminated via a current collector 33. The laminated body shown in FIG. 3 is arrange | positioned inside the case 22c of the cell 22 via an insulator, for example. The current collector 33 at a predetermined position is connected to the terminal 22a or the terminal 22b.

  The internal structure of the unit cell is not limited to a rectangular parallelepiped laminated body, and an arbitrary shape can be adopted. For example, a laminate of a positive electrode layer, a negative electrode layer, and an electrolyte layer may be formed in a band shape, and a roll of the belt-like laminate body may be disposed inside the case.

  Each of the positive electrode layer 30, the negative electrode layer 31, and the electrolyte layer 32 in the present embodiment is solid and formed of powder. The positive electrode layer, the negative electrode layer, and the electrolyte layer in the present embodiment can be formed by compressing powder as a material with a press.

The positive electrode layer 30 has a particulate positive electrode active material. As the positive electrode active material, any material that can be employed in an all-solid battery can be employed. As the positive electrode active material, for example, a layered composite oxide powder of lithium and transition metal such as LiCoO ₂ or LiNiO ₂ , a spinel type powder such as LiMn ₂ O ₄ , or an olivine type powder such as LiFePO ₄ is used. be able to. The negative electrode layer 31 has a particulate negative electrode active material. As the negative electrode active material, any material that can be employed in an all-solid battery can be employed. As the negative electrode active material, for example, a metal-based active material such as In powder or Al powder, or a carbon-based active material such as mesocarbon microbead powder can be used.

The electrolyte layer has a particulate solid electrolyte having ionic conductivity. As the solid electrolyte, any substance that can be employed in an all-solid battery can be employed. As the solid electrolyte, for example, a sulfide-based solid electrolyte or an oxide-based solid electrolyte can be used. As the sulfide-based solid electrolyte, Li ₂ S—P ₂ S ₅ powder, 70Li ₂ S-30P ₂ S ₅ powder, Li ₂ S—SiS ₂ powder, or the like can be used. As the oxide-based solid electrolyte, Li ₂ S—P ₂ O ₅ powder or the like can be used.

  A current collector 33 for collecting current is disposed outside the positive electrode layer 30 and the negative electrode layer 31. The current collector 33 in the present embodiment is formed of a metal foil. As the current collector, for example, a material such as aluminum, stainless steel, or copper can be used.

  In the all solid state battery of the present embodiment, all of the positive electrode layer, the negative electrode layer, and the electrolyte layer are formed of powder. However, the present invention is not limited to this form, and the all solid state battery includes, for example, a metal electrode layer. It doesn't matter.

  FIG. 4 shows a schematic cross-sectional view when the battery module in the present embodiment is cut along the longitudinal direction. With reference to FIGS. 1, 2, and 4, an arrow 51 indicates a downward direction in the vertical direction. The battery module in the present embodiment includes a plurality of single cells 22. The plurality of single cells 22 are arranged side by side in one direction.

  In the present embodiment, the terminals 22a and 22b of the unit cell 22 are electrically connected to the terminals 22a and 22b of the adjacent unit cells via a bus bar 27 as a conductive member. The positive terminal 22 a of one unit cell 22 is connected to the negative terminal 22 b of another adjacent unit cell 22. In the battery module of the present embodiment, a plurality of single cells 22 are electrically connected in series. The connection method of the plurality of unit cells 22 is not limited to series, and all the unit cells or some of the unit cells may be connected in parallel.

  An external connection terminal 28 a is connected via a bus bar 27 to a terminal 22 a of the unit cell 22 at one end in the direction in which the plurality of unit cells 22 are arranged. In addition, an external connection terminal 28 b is connected via a bus bar 27 to the terminal 22 b of the unit cell 22 at the other end in the direction in which the plurality of unit cells 22 are arranged. The external connection terminals 28 a and 28 b are formed so as to penetrate the sealed container 24 and protrude outside the sealed container 24. The external connection terminals 28a and 28b are terminals for supplying electricity to an external device by discharging or receiving electricity from an external device for charging. For example, a device for charging / discharging is connected to the external connection terminals 28a and 28b.

  FIG. 5 shows an enlarged schematic perspective view of a portion where the unit cell in the present embodiment is supported by the sealed container. FIG. 5 is an enlarged schematic perspective view of the lower part of the unit cell in the vertical direction. The unit cell 22 in the present embodiment is supported by the sealed container 24 via a positioning member 41 as a support member. The lower end of the unit cell 22 in the vertical direction is supported by the base material 24a. Further, the upper end of the unit cell 22 in the vertical direction is supported by the lid member 24b.

  FIG. 6 shows a schematic cross-sectional view when the battery module in the present embodiment is cut in a direction perpendicular to the direction in which the cells are arranged. The positioning member 41 in the present embodiment is formed so as to support a rectangular parallelepiped corner portion of the unit cell 22. The positioning member 41 in the present embodiment is formed such that almost all of the area with the largest area in the case 22c of the unit cell 22 is exposed and the area with the largest area is in contact with the fluid. The positioning member 41 in the present embodiment is formed such that a gap is generated between the unit cell 22 and the wall surface of the sealed container 24. As a supporting member which supports a cell, it is not restricted to said form, The supporting member for performing arbitrary positioning is employable.

  Referring to FIGS. 1, 4, and 6, unit cells 22 in the present embodiment are arranged so that the maximum area surfaces are parallel to each other. The plurality of single cells 22 are arranged away from each other. A gap is formed between each unit cell 22. A gap is formed between the unit cell 22 and the wall surface of the sealed container 24. In the battery module according to the present embodiment, a flow path through which the gas filled in the sealed container 24 flows is formed around the unit cell 22.

  The inside of the sealed container 24 in the present embodiment is filled with a pressurized gas and sealed. The unit cell 22 is pressed by the surrounding gas. Although the positive electrode active material or the negative electrode active material expands or contracts with charging and discharging, the occurrence of cracks in the positive electrode layer 30 and the negative electrode layer 31 due to the expansion and contraction can be suppressed. Moreover, since the volume change of the positive electrode layer 30 and the negative electrode layer 31 can be suppressed, it is possible to suppress the positive electrode layer 30 or the negative electrode layer 31 from being separated from the current collector 33. Moreover, since the battery module in this Embodiment is pressing the unit cell 22 with gas, it can press the whole unit cell 22 uniformly.

  By the way, as a method of pressing the unit cells, for example, the constraining plates can be fixed to each other with a fixing rod or the like with the maximum surface area of the unit cells sandwiched between the constraining plates. When the cells are mechanically pressed by the restraining plate and the fixing rod, the distance between the restraining plates is kept constant. For this reason, when a cell deform | transforms, the pressure which presses a cell may change. For example, when the unit cell is gradually deformed due to long-term use, the pressing pressure may change. On the other hand, in the present embodiment, since the unit cell is pressed by gas, the pressing can be continued with a substantially constant pressure even if the unit cell is deformed.

  Furthermore, the unit cell in the present embodiment is an all solid state battery. The all solid state battery has a solid positive electrode layer, a solid electrolyte layer, and a solid negative electrode layer. For this reason, an interface between the solid layers of the electrolyte layer 32 and the positive electrode layer 30 or the negative electrode layer 31 exists inside the unit cell 22. By pressing the unit cell, the resistance at the interface between the solid layers can be reduced. Furthermore, it can suppress that peeling etc. arise in the interface of solid layers and internal resistance increases. For this reason, deterioration of electrical characteristics such as a decrease in the capacity of the battery module can be suppressed.

  By the way, the inside of the airtight container in this Embodiment is sealed. For this reason, it is difficult to cool the unit cell 22 by continuously flowing a new fluid from the outside around the unit cell 22, and the gas sealed inside the sealed container 24 stays. The heat generated in the unit cell 22 is released to the outside of the battery module through the gas filled in the sealed container 24 and the sealed container 24. For example, the cooling can be performed by flowing a cooling fluid around the sealed container 24 of the battery module.

  The unit cell 22 in the present embodiment is fixed to the sealed container 24 so that the terminals 22a and 22b are arranged below the case 22c. The terminals 22a and 22b are arranged so as to face the lower side in the vertical direction. In the present embodiment, all the terminals 22a and 22b are arranged so as to face the lower side in the vertical direction.

  In the cell 22, since a large amount of current flows through the terminals 22 a and 22 b, the terminals 22 a and 22 b have a higher temperature than other parts. For this reason, if the use is continued, the temperature of the gas around the terminals 22a and 22b rises. The gas whose temperature has risen rises toward the top of the sealed container 24 because of its lower density. The low temperature gas staying in the upper part descends toward the lower part of the sealed container 24. As a result, as shown by an arrow 53, a gas flow is generated inside the sealed container 24.

  Thus, by arranging the terminals 22a and 22b in the lower part of the case 22c in the vertical direction, convection can be generated inside the sealed container 24. A flow is generated in the gas inside the sealed container 24, and the temperature difference between the upper part and the lower part of the sealed container 24 can be reduced. For this reason, it can suppress that the temperature gradient of the vertical direction arises in the cell 22.

  In the single battery of the present embodiment, lithium ions easily move as the temperature increases. For this reason, there is a problem that the portion where the temperature is high is more rapidly deteriorated than the portion where the temperature is low. As a result, the electrical characteristics of the battery module are deteriorated or a failure is likely to occur. Since the battery module in the present embodiment can suppress a temperature gradient from occurring in a single cell, it can suppress deterioration in electrical characteristics. Moreover, the occurrence of failure can be suppressed.

  Taking the comparative example as an example, when the terminal of the unit cell is arranged in the upper part of the case in the vertical direction, the gas whose temperature has increased around the terminal stays in the upper part of the sealed container. As a result, the temperature of the upper part of the sealed container is increased, and the temperature of the lower part of the sealed container is decreased. A temperature gradient occurs in the vertical direction inside the sealed container. Even in the unit cell, a temperature gradient is generated in which the temperature gradually increases toward the upper side in the vertical direction. Due to the temperature gradient in the unit cell, the electrical characteristics of the unit cell are deteriorated.

  In contrast to the comparative example, in the battery module of the present embodiment, the gas whose temperature has increased in the vicinity of the terminals 22a and 22b rises toward the top of the sealed container, and thus the gas circulates inside the sealed container. . Since the gas also flows in the vertical direction, the temperature gradient in the vertical direction can be reduced and the unit cell 22 can be cooled uniformly. For this reason, it can suppress that the temperature gradient of the vertical direction arises in the cell 22. The deterioration of the electrical characteristics of the unit cell 22 can be suppressed.

  As described above, in the present embodiment, it is possible to uniformly pressurize the periphery of the unit cell with the fluid, and to suppress a vertical temperature gradient generated in the unit cell. As a result, deterioration of the electrical characteristics of the battery module can be suppressed.

  In the battery module of the present embodiment, the plurality of single cells are arranged apart from each other, a gap is formed between the single cells and the wall surface of the sealed container, and a flow for circulating gas around the single cells. A road is formed. By adopting this configuration, it is possible to efficiently raise the gas whose temperature has increased in the vicinity of the terminals 22a and 22b. Convection can be easily generated inside the sealed container 24. As a result, the vertical temperature gradient of the unit cell can be more effectively suppressed. In the present embodiment, a gas flow path is formed around all the outer peripheral surfaces of the unit cell case. However, the present invention is not limited to this configuration, and a part of the outer peripheral surface contacts the sealed container. It does not matter.

  The unit cell in the present embodiment is supported by the sealed container via the positioning member, but is not limited to this form, and can be supported by the optional container. For example, a spacer may be disposed between the single cells. Alternatively, a part of the unit cell may be directly supported by the sealed container.

  The unit cell in the present embodiment has been described by exemplifying an all-solid-state battery among lithium ion batteries. However, the unit cell is not limited to this mode, and the present invention is not limited to this mode. The invention can be applied. For example, the present invention can be applied to a lithium ion battery or the like in which the electrolyte layer is formed of a liquid.

  In the battery module of the present embodiment, the sealed container is always sealed. However, the present invention is not limited to this form, and the sealed container may be formed so as to be able to be sealed. For example, a pressure adjusting device that adjusts the internal pressure may be connected to the sealed container, and the internal pressure may be adjusted when the battery module is used.

  Further, in the battery module of the present embodiment, the terminals of the unit cells are connected to each other through the bus bar, and the terminals of the unit cell are connected to the external connection terminal through the bus bar. The terminals of the unit cells and the terminals of the unit cells and the external connection terminals can be connected by any electrical connection method. Further, the number of external connection terminals is not limited to two, that is, a positive electrode and a negative electrode, and an arbitrary number can be arranged.

  Moreover, in this Embodiment, gas is employ | adopted as a fluid with which the inside of an airtight container is filled, but it is not restricted to this form, Arbitrary fluid can be filled into the inside of an airtight container. For example, the inside of the sealed container may be filled with a liquid.

  The above embodiments can be combined as appropriate. In the respective drawings described above, the same or equivalent parts are denoted by the same reference numerals. In addition, said embodiment is an illustration and does not limit invention. In the embodiment, the change shown in a claim is included.

22 unit cell 22a, 22b terminal 22c case 24 airtight container 30 positive electrode layer 31 negative electrode layer 32 electric field layer 41 positioning member

Claims (3)

A unit cell having a case and a terminal protruding from the case;
A cell is accommodated inside, and a hermetically sealed container is provided.
The sealed container is filled with pressurized fluid with the inside sealed.
The battery module is characterized in that the battery is housed in a sealed container so that the terminals are arranged at the lower part of the case. Provided with a plurality of single cells housed in a sealed container,
The plurality of single cells are arranged apart from each other, and a flow path through which fluid flows is formed between the single cells,
The battery module according to claim 1, wherein a gap is formed between the unit cell and the wall surface of the sealed container, and a flow path through which a fluid flows is formed between the unit cell and the wall surface of the sealed container.   3. The battery module according to claim 1, wherein the single battery includes an all-solid battery having a solid positive electrode layer, a solid electrolyte layer, and a solid negative electrode layer.

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