JP2013093135A - Unit cell and power storage device with unit cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a unit cell that suppress application of excess voltage.SOLUTION: An all-solid type unit cell 22 stores in an outer package 22c a laminate body 38 including a plurality of cell elements 35. The inside of the outer package 22c is filled with an inert gas. The unit cell 22 is formed so that gas is ionized and discharge occurs in a discharge region 51 in the inside of the outer package 22c when a voltage between a collector 33a of the laminate body 38 and a collector 33b having a lower potential than the collector 33a exceeds a predetermined upper limit voltage.

Description

  The present invention relates to a single battery and a power storage device including the single battery.

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

  Among the single cells, the secondary battery can be charged and discharged, so that the demand has been rapidly expanding in recent years. Rechargeable secondary batteries include nickel cadmium batteries, nickel metal hydride batteries, lithium ion batteries, and the like. These secondary batteries can be charged by supplying electricity from the charge / discharge circuit. However, if the battery is excessively charged, it may become a so-called overcharged state, and performance deterioration may occur. Used with control. For example, when a lithium ion battery is overcharged, performance deterioration such as a decrease in electric capacity may occur. Thus, the secondary battery is preferably charged within a predetermined range.

  Japanese Unexamined Patent Application Publication No. 2009-152129 discloses a battery pack that includes a thermistor for the overcharge detection circuit to detect the temperature of the battery pack. In this battery pack, when the thermistor detects that the lithium ion battery has become higher than a predetermined temperature, the overcharge detection circuit switches the threshold voltage for detecting overcharge, It is disclosed to detect overcharge before

  Further, in Japanese Patent Application Laid-Open No. 11-55866, in a battery charging device having a plurality of unit cells, a capacity limiting cell that reaches the discharge lower limit voltage most quickly when the battery is discharged is detected, and the charge upper limit voltage is set during charging. It is detected as the upper limit voltage cell that reaches the earliest. When it is determined that the capacity limit cell and the upper limit voltage cell are equal, charging is performed while controlling so that the terminal voltage of the upper limit voltage cell does not exceed the charge upper limit voltage.

JP 2009-152129 A Japanese Patent Laid-Open No. 11-55866

  The secondary battery and the charging device are provided with a protection circuit for interrupting charging so that the battery is not overcharged during charging. Various types of overcharge protection circuits have been proposed. For example, as disclosed in the above Japanese Patent Application Laid-Open No. 2009-152129, it is known that a protection circuit is provided inside the battery pack to detect an increase in temperature and avoid overcharging. . Such a protection circuit for preventing overcharge requires a control IC (integrated circuit), a control switch, etc. for controlling the protection circuit, and even when the secondary battery is not used, Since the standby current flows, there is a problem that the capacity of the stored electricity is reduced or the life of the battery is shortened. In addition, when an excessive voltage is applied to the battery due to a failure of the protection circuit of the charging device for the secondary battery, there arises a problem that the performance of the battery is deteriorated.

  An object of this invention is to provide the cell and electrical storage apparatus which suppress that an excessive voltage is applied.

  The unit cell of the present invention is an all-solid type unit cell in which a power storage unit including a plurality of battery elements is housed in an exterior body, and the interior of the exterior body is filled with an inert gas. The first conductive member and the second conductive member having a lower potential than the first conductive member. When the voltage between the first conductive member and the second conductive member becomes larger than a predetermined upper limit voltage, the gas is ionized inside the exterior body so that a discharge is generated. Has been.

  In the above invention, the first discharge electrode connected to the first conductive member and the second discharge electrode connected to the second conductive member are provided. The distance between the first discharge member and the second discharge electrode is smaller than the distance between the first conductive member and the second conductive member. It is preferable that a discharge occurs between the first discharge electrode and the second discharge electrode when the voltage between the conductive member becomes larger than a predetermined upper limit voltage.

  In the said invention, the gas with which the inside of an exterior body is filled can contain at least 1 gas among argon, helium, neon, krypton, xenon, and nitrogen.

  The power storage device of the present invention includes a power storage unit that can be charged, an exterior body that houses the power storage unit, a single battery that includes a terminal protruding from the exterior body, and a container that houses at least one single battery inside. The inside of the container is filled with an inert gas. The terminal of the unit cell includes a first terminal and a second terminal having a lower potential than the first terminal, and a voltage between the first terminal and the second terminal is a predetermined upper limit voltage. When it becomes larger than this, the gas is ionized inside the container so that a discharge is generated.

  In the above invention, the first discharge electrode connected to the first terminal and the second discharge electrode connected to the second terminal are provided, the first discharge electrode and the second discharge electrode. The distance between the first terminal and the second terminal is smaller than the distance between the first terminal and the second terminal, and the voltage between the first terminal and the second terminal is predetermined. It is preferable that a discharge occurs between the first discharge electrode and the second discharge electrode when the voltage exceeds the upper limit voltage.

  In the above-described invention, a plurality of unit cells are provided, and a positive electrode side terminal of one unit cell can constitute a first terminal, and a negative electrode side terminal of another unit cell can constitute a second terminal. .

  In the above invention, the container includes a sealed container formed so as to be hermetically sealed, and the outer casing of the unit cell is formed to be deformable by applying pressure from the outside and is filled in the sealed container. The gas is preferably pressurized so as to be greater than atmospheric pressure.

  In the said invention, the gas with which the inside of the container which accommodates a cell is filled can contain at least 1 gas among argon, helium, neon, krypton, xenon, and nitrogen.

  ADVANTAGE OF THE INVENTION According to this invention, the single cell and electrical storage apparatus which suppress that an excessive voltage is applied can be provided.

2 is a schematic cross-sectional view of a first unit cell in the first embodiment. FIG. 3 is a schematic perspective view of a first unit cell in the first embodiment. FIG. 3 is an enlarged schematic cross-sectional view of a laminated body inside a first unit cell in the first embodiment. FIG. It is a graph explaining the discharge voltage with respect to the distance and pressure of the electrodes of a parallel plate. 3 is a schematic cross-sectional view of a second unit cell in the first embodiment. FIG. FIG. 3 is an enlarged schematic cross-sectional view of a laminated body inside a second unit cell in the first embodiment. 3 is a schematic cross-sectional view of a third unit cell in the first embodiment. FIG. 4 is a schematic cross-sectional view of a fourth unit cell in the first embodiment. FIG. 6 is a schematic cross-sectional view of a fifth unit cell in the first embodiment. FIG. 6 is a schematic cross-sectional view of a sixth unit cell in the first embodiment. FIG. FIG. 3 is a schematic cross-sectional view of a first power storage device in a second embodiment. 6 is a schematic perspective view of a single battery of a first power storage device in Embodiment 2. FIG. 6 is a schematic cross-sectional view of a single battery of a first power storage device in Embodiment 2. FIG. 6 is a schematic cross-sectional view of a second power storage device in Embodiment 2. FIG. 6 is a schematic cross-sectional view of a third power storage device in Embodiment 2. FIG.

(Embodiment 1)
With reference to FIGS. 1 to 10, the single battery and the power storage device in the first embodiment will be described. The power storage device in the present embodiment includes a single battery as a battery cell and a container that houses the single battery.

  FIG. 1 shows a schematic cross-sectional view of a unit cell in the present embodiment. In the present embodiment, a lithium ion battery will be described as an example of rechargeable secondary batteries. The unit cell 22 in the present embodiment includes a battery element 35 and includes a power storage unit capable of storing power. The power storage unit in the present embodiment is configured by a stacked body 38 in which a plurality of battery elements 35 are stacked. The stacked body 38 is connected to terminals 22a and 22b for connection to an external device. The unit cell 22 includes an exterior body 22c that houses the stacked body 38 therein. The terminals 22a and 22b are formed so as to protrude from the exterior body 22c.

  FIG. 2 shows a schematic perspective view of the unit cell in the present embodiment. Referring to FIGS. 1 and 2, unit cell 22 in the present embodiment is formed in a rectangular parallelepiped shape. The terminals 22a and 22b are parts that conduct electricity. The terminal 22a is a positive electrode and the terminal 22b is a negative electrode. The respective terminals 22 a and 22 b are connected to the charge / discharge circuit 40.

  The exterior body 22c is formed so as to be able to seal the internal gas. The exterior body 22c in the present embodiment is formed of a metal such as aluminum. The exterior body 22c is not limited to this form, and can be formed of a material capable of sealing the internal gas.

  In FIG. 3, the expanded schematic sectional drawing of the laminated body of the cell in this Embodiment is shown. The stacked body 38 in the present embodiment is electrically connected in series by stacking a plurality of battery elements 35. The battery element 35 includes 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. Further, the battery element 35 includes a current collector 33. In the laminated body 38 shown in FIG. 3, the positive electrode layer 30, the negative electrode layer 31, and the electrolyte layer 32 are laminated via a current collector 33.

  The unit cell 22 in the present embodiment is an all solid state battery. Each of positive electrode layer 30, negative electrode layer 31, and electrolyte layer 32 in the present embodiment is solid. In the present embodiment, each layer is formed of powder. The positive electrode layer 30, the negative electrode layer 31, and the electrolyte layer 32 in the present embodiment can be formed, for example, by compressing a material powder using 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 and a semi-metallic active material such as Si, or a carbon-based active material such as mesocarbon microbead powder can be used. In addition, oxides such as Li ₄ Ti ₅ O ₁₂ , TiO ₂ , and Fe ₂ O ₃ can also be used as the negative electrode active material.

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 in the present embodiment, 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 , Li ₂ S—SiS ₂ , Li ₂ S—GeS ₂ , or the like can be used. Li ₂ S—P ₂ O ₅ or the like can be used as the oxide-based solid electrolyte. Alternatively, Li _0.35 La _0.55 TiO ₃ , Li _2.9 PO _3.3 N _0.46, or the like can be used.

  The solid electrolyte is not limited to inorganic solid electrolytes such as sulfides and oxides, and organic polymer electrolytes can be employed. As the organic polymer electrolyte employed in the all solid state battery, it is preferable to use a completely solidified electrolyte called an intrinsic polymer. Alternatively, the organic polymer electrolyte may be a gel solid electrolyte. Examples of the organic polymer electrolyte include polyethylene oxide containing lithium salt, polypropylene oxide, polyvinylidene fluoride, polyacrylonitrile, and the like.

  A current collector 33 is disposed on the outer side of each positive electrode layer 30 and negative electrode layer 31 of the stacked body 38. 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, copper, nickel, titanium, or platinum can be used. Further, a current collector with a modified surface can be used.

  In the all solid state battery of the present embodiment, the positive electrode layer, the negative electrode layer, and the electrolyte layer are formed by compressing powder. However, the present invention is not limited to this form. It doesn't matter if it exists. For example, the respective layers may be formed by sintering and integrating powders as materials. Alternatively, each layer may be formed of a polymer (resin). In addition to the active material, the positive electrode layer and the negative electrode layer may contain a solid electrolyte, a conductive additive, a binder, and the like. The electrolyte layer may contain a binder or the like in addition to the solid electrolyte.

  The power storage unit of the unit cell is not limited to a rectangular parallelepiped stacked 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 wound body of the belt-like laminate body may be disposed inside the exterior body.

  With reference to FIG. 1, the laminated body 38 in this Embodiment is the collector 33a arrange | positioned at the edge part by the side of the positive electrode of the laminated body 38, and the collector currently arrange | positioned by the edge part by the side of a negative electrode. 33b. The current collector 33a is connected to a positive terminal 22a connected to an external device. The current collector 33b is connected to a negative terminal 22b connected to an external device.

  The current collector 33a disposed at one end of the stacked body 38 in the present embodiment functions as a first conductive member for causing discharge. Further, the current collector 33b disposed at the other end of the stacked body 38 functions as a second conductive member having a lower potential than the first conductive member for generating discharge.

  The unit cell 22 in the present embodiment is filled with a gas that causes the gas to ionize inside the exterior body 22c to cause discharge. An inert gas can be exemplified as the gas filled in the exterior body 22c. For example, a gas including at least one of a rare gas such as argon, helium, neon, krypton, and xenon and nitrogen can be exemplified. A gas such as argon is a gas that is easily discharged, and since it is an inert gas, even if a discharge occurs and an ionized gas is formed, an active substance or the like is hardly generated, and the discharge adversely affects other members. Can be suppressed.

  Regarding the pressure inside the exterior body 22c, if the air pressure inside the exterior body 22c becomes too high, it is necessary to form the exterior body 22c firmly in order to withstand the internal pressure. Or the exterior body 22c becomes large. For this reason, it is preferable that the pressure of the gas with which the exterior body 22c is filled is, for example, 10 atm or less.

  In the present embodiment, the charging / discharging circuit 40 arranged outside the unit cell 22 applies a voltage between the terminal 22a and the terminal 22b to charge the unit cell 22. In the present embodiment, constant current charging is performed by the charge / discharge circuit 40. That is, electricity is supplied to the unit cell 22 so that the current value when charging is substantially constant.

  When the capacity of electricity remaining in the unit cell 22 is small, such as at the start of charging, the voltage (potential difference) between the terminal 22a and the terminal 22b is small. The voltage between the terminals 22a and 22b increases as the capacity of the unit cell 22 charged and stored increases. Charging can be terminated when the voltage between the terminals 22a and 22b of the unit cell 22 reaches a predetermined upper limit voltage. For example, the voltage when the capacity of electricity reaches a predetermined capacity can be set as the upper limit voltage for terminating charging.

  In the exterior body 22c, the voltage between the current collector 33a and the current collector 33b increases with charging. In the unit cell 22 in the present embodiment, when the voltage between the current collector 33a and the current collector 33b exceeds the upper limit voltage for ending charging, dielectric breakdown occurs in the exterior body 22c. It is formed so that electric discharge occurs. In the present embodiment, the gas between the current collector 33a and the current collector 33b is ionized to generate a discharge, and the ionized gas 50 is generated. A region between the current collector 33 a and the current collector 33 b becomes a discharge region 51. The discharge in the present embodiment is, for example, a spark discharge.

  By generating a discharge inside the exterior body 22c, a voltage increase between the current collector 33a and the current collector 33b can be suppressed. It can suppress that the cell 22 is charged exceeding the predetermined electric capacity. That is, overcharge can be suppressed. Or, when the external charging / discharging circuit 40 fails, a large voltage may be applied to the terminals 22a and 22b of the unit cell 22 in some cases. Even in such a case, a large voltage can be suppressed from being applied to the stacked body 38 serving as a power storage unit, and the stacked body 38 can be protected. The single battery in this embodiment can suppress an excessive voltage from being applied to the single battery regardless of electronic control.

  Further, when a protection circuit for preventing overcharging is provided in the unit cell, a standby current flows through the protection circuit even when the unit cell is not used. For this reason, the capacity | capacitance of the electricity stored in the unit cell is reduced, and the life of the battery is shortened because the number of times of charging and discharging is increased. In the unit cell of the present embodiment, since no discharge occurs when not used, it is possible to avoid a current from flowing between the first conductive member and the second conductive member. That is, it is possible to suppress a decrease in the electric capacity stored in the unit cell or a decrease in the lifetime of the unit cell.

  Furthermore, when the electrolyte layer is liquid, overcharge can be suppressed by a method of adding a redox shuttle agent or a method of adding a polymerizing agent, but the electrolyte layer is solid in an all-solid battery. Moreover, it is difficult to apply such a method. However, as in this embodiment, the all-solid-state battery can have a function of suppressing overcharge and the like by causing discharge inside the exterior body.

  In the example shown in FIG. 1, the discharge region 51 as a region in which the ionized gas 50 is generated is disposed on the side of the stacked body 38, but is not limited to this configuration, and the discharge region 51 is not limited to the stacked body 38. It may be inside. That is, a discharge may occur inside the stacked body 38.

  Next, a configuration for generating discharge at a predetermined upper limit voltage inside the exterior body 22c will be described. In the unit cell 22 of the present embodiment, the pressure of the gas inside the exterior body 22c is generated so that discharge occurs when the voltage between the current collectors 33a and 33b becomes larger than a predetermined upper limit voltage. And the type of gas is selected.

  FIG. 4 is a graph for explaining the relationship between the distance between electrodes causing discharge and the pressure of gas and the voltage at which discharge occurs. The graph of FIG. 4 is a graph based on Paschen's law and explains the discharge voltage when parallel plate electrodes are arranged in a predetermined gas atmosphere.

  The horizontal axis represents a value obtained by multiplying the distance d between the parallel plate electrodes by the pressure p of the space in which the electrodes are arranged. When the variable pd decreases from a large value, the voltage Vi at which discharge occurs decreases, but when the variable pd is less than the predetermined value, the voltage Vi at which discharge occurs increases as the variable pd decreases. For example, when the distance d between the electrodes is constant, the voltage Vi required to cause discharge decreases as the pressure decreases from atmospheric pressure to a predetermined atmospheric pressure. Below the predetermined atmospheric pressure, as the pressure decreases, the voltage Vi required to cause discharge increases.

  Even when the gas causing the discharge is changed, the same tendency is exhibited when the variable pd is changed, but the magnitude of the voltage Vi necessary for causing the discharge changes. Thus, for example, the voltage at which discharge occurs can be adjusted by changing the type of gas filled in the exterior body or changing the atmospheric pressure filled in the exterior body. Furthermore, as will be described later, the voltage Vi at which discharge occurs can be adjusted by changing the distance between the electrodes at which discharge occurs or by changing the shape or material of the electrode at which discharge occurs.

  FIG. 5 shows a schematic cross-sectional view of the second unit cell in the present embodiment. The second cell 22 has a stacked body 38 including a plurality of battery elements 35. In the laminated body 38, the battery elements 35 are electrically connected by the connection member 36.

  FIG. 6 shows an enlarged schematic cross-sectional view of the second unit cell stack in the present embodiment. The battery element 35 of the second unit cell has a current collector 33 disposed on both sides of the positive electrode layer 30, the negative electrode layer 31, and the electrolyte layer 32. A current collector 33 on the negative electrode side of one battery element 35 and a current collector 33 on the positive electrode side of another battery element 35 are connected by a connecting member 36. In the present embodiment, a plurality of battery elements 35 are electrically connected in series. The connection method of the battery elements 35 is not limited to serial connection, and at least some of the battery elements 35 may be connected in parallel. As described above, in the stacked body 38 as the power storage unit, a plurality of battery elements 35 may be electrically connected by the connection member 36.

  Referring to FIG. 5, also in second unit cell 22 in the present embodiment, current collector 33 a arranged at the end on the positive electrode side of laminate 38 and the end on the negative electrode side of laminate 38 A discharge can be generated in the discharge region 51 when the voltage between the current collector 33b and the current collector 33b disposed in the region exceeds a predetermined upper limit voltage. As a result, it is possible to suppress overcharge or to prevent an excessive voltage from being applied to the laminate.

  FIG. 7 shows a schematic cross-sectional view of the third unit cell in the present embodiment. The third unit cell includes a first discharge electrode 37a connected to a current collector 33a serving as a first conductive member and a current collector 33b serving as a second conductive member. 2 discharge electrodes 37b. The distance between the first discharge electrode 37a and the second discharge electrode 37b is formed to be smaller than the distance between the positive current collector 33a and the negative current collector 33b. . The first discharge electrode 37a and the second discharge electrode 37b in the present embodiment are formed in a rod shape. The first discharge electrode 37a and the second discharge electrode 37b are formed so that the tip portions face each other.

  The discharge electrodes 37a and 37b can be formed of any material that suppresses deformation even by heat during discharge. For example, iron, stainless steel, nickel, aluminum, copper, platinum, tungsten, or the like can be used as the material of the discharge electrode. The discharge electrodes 37a and 37b in the present embodiment are formed so that the tip portions facing each other are pointed. Thus, by making the tip of the discharge electrode thinner, it is possible to easily generate discharge. The shape of the discharge electrode is not limited to this, and any shape such as a plate shape, a needle shape, a column shape, or a spherical shape can be adopted.

  In the third unit cell of the present embodiment, discharge can be preferentially generated in a region sandwiched between the first discharge electrode 37a and the second discharge electrode 37b. A region between the first discharge electrode 37 a and the second discharge electrode 37 b can be set as the discharge region 51. For this reason, the space | interval of the electrodes which produce discharge can be adjusted arbitrarily. The distance between the discharge electrodes 37a and 37b can be set so that discharge occurs at a predetermined desired voltage. In addition, since the position where discharge is generated can be arbitrarily set, the distance between the discharge region 51 and the stacked body 38 can be increased. For this reason, the influence with respect to the laminated body 38 of the heat | fever and electromagnetic waves accompanying discharge can be reduced. Furthermore, the laminate 38 can be formed with an arbitrary thickness. For example, the number of stacked battery elements 35 can be increased, and the stacked body 38 can be formed thick. By forming the stacked body 38 thick, the energy density of the unit cell can be improved.

  In the third unit cell of the present embodiment, in addition to the type and pressure of the gas filled in the exterior body 22c, the material of the discharge electrodes 37a and 37b, the distance between the discharge electrodes 37a and 37b, Further, by selecting the shape of the discharge electrodes 37a and 37b, it is possible to cause discharge at a desired voltage based on the upper limit voltage of the power storage unit or the like.

  For example, the laminated body 38 in which 38 battery elements 35 are connected in series is provided, and dry argon is used as a gas filling the exterior body 22c, and the pressure inside the exterior body 22c is set to 1 atmosphere. When parallel plate electrodes are used as the discharge electrodes 37a and 37b and the upper limit voltage applied to one battery element 35 is about 5V, the upper limit voltage that can be applied to the current collectors 33a and 33b of the stacked body 38 is It can be set to about 190V. In this case, by setting the distance between the first discharge electrode 37a and the second discharge electrode 37b to 15.8 μm, the voltage at which discharge occurs in the region between the discharge electrodes 37a and 37b is set to 192V. be able to. For this reason, for example, when the voltage between the current collector 33a and the current collector 33b exceeds about 190 V during charging, discharge occurs in the discharge region 51 to avoid overcharging. it can.

  FIG. 8 shows a schematic cross-sectional view of the fourth unit cell in the present embodiment. In the third unit cell of the present embodiment, the discharge electrodes 37 a and 37 b are arranged on one side of the side of the stacked body 38. On the other hand, in the fourth unit cell of the present embodiment, discharge electrodes 37a and 37b are arranged on both sides of the side of the stacked body 38. Thus, discharge electrodes can be arranged at a plurality of locations. With this configuration, it is possible to generate discharge more reliably when a desired voltage is reached.

  FIG. 9 shows a schematic cross-sectional view of the fifth unit cell in the present embodiment. In the fifth unit cell of the present embodiment, the current collector 33c at the center in the stacking direction of the stacked body 38 extends laterally. A discharge electrode 37a is connected to the current collector 33a on the positive electrode side of the laminate 38. The discharge electrode 37a and the current collector 33c are close to each other and face each other. A discharge region 51 can be formed between the discharge electrode 37a connected to the current collector 33a and the current collector 33c. In this discharge portion, the current collector 33a functions as a first conductive member, and the current collector 33c functions as a second conductive member.

  A discharge electrode 37a is connected to the current collector 33c. The discharge electrode 37a and the current collector 33b on the negative electrode side are close to each other and face each other. A discharge region 51 can be formed between the discharge electrode 37a connected to the current collector 33c and the current collector 33b. In this discharge portion, the current collector 33c functions as a first conductive member, and the current collector 33b functions as a second conductive member. In the fifth unit cell of the present embodiment, the current collector 33c functions as the second conductive member in one discharge portion, and the current collector 33c is the first conductive member in the other discharge portion. It functions as a conductive member.

  Thus, in the fifth unit cell, discharge is generated between the end portion in the stacking direction of the stacked body and the middle portion in the stacking direction. The discharge is generated when the voltage between the current collectors 33a and 33b at the end of the laminated body 38 and the current collector 33c in the middle of the laminated body 38 is higher than a predetermined upper limit voltage. Is formed.

  In the fifth unit cell of the present embodiment, the discharge electrode 37a is connected to the current collector 33a, and the discharge electrode 37a is connected to the current collector 33c. However, the present invention is not limited to this configuration. 37a may not be arranged. Even in this case, a discharge can be generated in the region between the current collector 33a and the current collector 33c and the region between the current collector 33c and the current collector 33b.

  FIG. 10 shows a schematic cross-sectional view of the sixth unit cell in the present embodiment. In the discharge electrode described above, a rod-shaped conductive member protrudes from the current collector, but the discharge electrodes 37a and 37b of the sixth unit cell have a shape in which the current collectors 33a and 33b are extended. Have. The discharge electrode 37a is connected to the flat current collector 33a, and the discharge electrode 37b is connected to the flat current collector 33b. Each discharge electrode 37a, 37b is formed in a plate shape. The discharge electrodes 37a and 37b of the sixth unit cell have shapes in which the respective current collectors 33a and 33b extend. The distal ends of the discharge electrodes 37a and 37b are arranged close to each other so as to face each other, and a discharge region 51 is formed. A discharge can be generated in the discharge region 51 when the voltage between the current collector 33a and the current collector 33b exceeds a desired upper limit voltage.

  In the present embodiment, a lithium ion battery has been described as an example of a single battery among all-solid batteries, but the present invention is not limited to this form and can be applied to any all-solid secondary battery. For example, the present invention can be applied to a rocking chair type secondary battery in which other ions such as protons, sodium ions, aluminum ions, copper ions, magnesium ions, or calcium ions move instead of lithium ions. Alternatively, the present invention can also be applied to a reserve type secondary battery.

(Embodiment 2)
With reference to FIGS. 11 to 15, the single battery and the power storage device in the second embodiment will be described. The power storage device in this embodiment includes a structure in which gas is ionized outside the unit cell to cause discharge.

  FIG. 11 is a schematic cross-sectional view of the first power storage device in this embodiment. FIG. 12 is a schematic perspective view of a single battery of the first power storage device in the present embodiment. Referring to FIGS. 11 and 12, the power storage device in the present embodiment includes a sealed container 24 as a container for housing unit cell 22 therein. The sealed container 24 is formed so that the inside can be sealed.

  In the power storage device of the present embodiment, the sealed container 24 is filled with a pressurized gas. In the present embodiment, the gas is filled at a pressure higher than atmospheric pressure. The gas filled in the sealed container 24 is preferably a gas that is chemically inert and that does not generate an active substance even when discharge occurs. As the gas filled in the sealed container 24, an inert gas can be exemplified. For example, a gas including at least one of a rare gas such as argon, helium, neon, krypton, and xenon and nitrogen can be exemplified.

  The unit cell 22 has a positive terminal 22a and a negative terminal 22b. The positive terminal 22a and the negative terminal 22b are arranged close to each other. Further, the terminals 22a and 22b of the unit cell 22 in the present embodiment are formed in a plate shape. The shape of the terminals 22a and 22b is not limited to this form, and any shape can be adopted. The terminals 22a and 22b are connected to the charge / discharge circuit 40. The unit cell 22 in the present embodiment has a rectangular parallelepiped shape, but is not limited to this form, and any shape can be adopted.

  The exterior body 22c of the unit cell 22 in the present embodiment is formed of a material that can be deformed by applying pressure from the outside. The exterior body 22c in the present embodiment is formed of an aluminum laminate film. The exterior body 22c is not limited to this form, and any material that can be deformed when pressure is applied from the outside can be employed.

  As a material that can be deformed when pressure is applied from the outside, for example, a polymer film, a metal film, or a composite laminated film in which a polymer film and a metal film are laminated can be employed. Examples of the polymer film material include polyethylene, nylon, and polypropylene. Examples of the material of the metal film include aluminum, stainless steel, nickel, and the like.

  FIG. 13 shows an enlarged schematic cross-sectional view of the unit cell in the present embodiment. The single battery in the present embodiment is an all solid-state lithium ion battery. FIG. 13 is a schematic cross-sectional view of the end of the unit cell 22 on the side where the terminals 22a and 22b are arranged. The terminal 22a on the positive electrode side is connected to the current collector 33a at the end on the positive electrode side of the stacked body 38. The negative terminal 22 b is connected to the current collector 33 b at the negative electrode end of the laminate 38.

  Referring to FIGS. 11 and 13, in the first power storage device of the present embodiment, unit cell 22 is accommodated in a sealed container 24 filled with a dischargeable gas. When the voltage between the positive terminal 22a and the negative terminal 22b of the unit cell 22 is larger than a predetermined upper limit voltage, a discharge occurs between the terminals 22a and 22b. Is formed. In the present embodiment, the gas is ionized in the discharge region 51 outside the exterior body 22c of the unit cell 22 so that discharge is generated.

  The type, pressure, and distance between the positive electrode side terminal 22a and the negative electrode side terminal 22b are set so that discharge occurs at a predetermined desired voltage. Yes. Moreover, it is preferable that the gas filled in the exterior body 22c is selected with the kind of gas and the atmospheric pressure that are less likely to cause discharge than the gas filled outside the exterior body 22c.

  In the first power storage device of the present embodiment, the positive terminal 22a of the unit cell 22 functions as the first terminal. Further, the negative terminal 22b functions as a second terminal having a lower potential than the first terminal. When the voltage between the terminals exceeds a predetermined upper limit voltage, discharge occurs inside the sealed container 24. For this reason, for example, when the voltage between the terminals 22a and 22b reaches the upper limit voltage of the power storage device during the charging period, discharge occurs in the discharge region 51 to suppress overcharge. Can do. Alternatively, when the external charging / discharging circuit 40 fails, a large voltage may be applied to the terminals 22a and 22b of the unit cell 22 in some cases. Even in such a case, it is possible to protect the unit cell by suppressing application of a large voltage to the power storage unit inside the unit cell 22.

  The power storage device in the present embodiment is preferably filled with a pressurized gas inside the sealed container 24. For example, it is preferable that the air pressure inside the sealed container 24 be higher than 1 atmosphere. The active material contained in the positive electrode layer or the negative electrode layer inside the unit cell 22 expands or contracts by repeatedly charging and discharging. When the positive electrode layer or the negative electrode layer expands or contracts, cracks may occur in each layer, or resistance at the interface between the layers may increase. The cell 22 can be pressurized with gas by filling the inside of the sealed container 24 with pressurized gas. By pressurizing the unit cell 22 with gas, it is possible to suppress the occurrence of cracks in each layer or increase in interface resistance. That is, it can suppress that the performance of a cell falls.

  On the other hand, if the pressure inside the sealed container 24 is too high, the sealed container 24 must have a strong structure. Alternatively, the sealed container 24 becomes large. The pressure of the gas filled in the sealed container 24 is preferably 10 atm or less, for example. Further, it is preferable that the gas filled in the sealed container 24 is not liquefied even at a high pressure inside the sealed container 24. For example, a gas that does not liquefy even when the pressure reaches 10 atm is preferable.

  Furthermore, it is preferable to connect a circulating device for circulating the gas inside the sealed container 24 to the sealed container. By circulating the gas inside the sealed container 24, the unit cell 22 can be efficiently cooled. Further, since the heat of the unit cell 22 is dissipated through the gas filled in the sealed container 24, the gas filled in the sealed container 24 may be a gas having high thermal conductivity. preferable.

  FIG. 14 is a schematic cross-sectional view of the second power storage device in this embodiment. The second power storage device of the present embodiment includes a plurality of unit cells 22. A plurality of unit cells 22 are accommodated in the sealed container 24. The plurality of unit cells 22 are electrically connected to each other. The second power storage device includes a single battery 22 shown in FIG. 12, and a single battery 22 in which a positive terminal 22a protrudes from one side of the outer package and a negative terminal 22b protrudes from the other side of the outer package. With.

  In the second power storage device of the present embodiment, each unit cell 22 is electrically connected in series. A terminal 22a on the positive side of one unit cell 22 is connected to a terminal 22b on the negative side of another unit cell 22 adjacent to each other. In the second power storage device of the present embodiment, a stacked body of unit cells 22 is configured. The stacked body of the unit cells 22 is accommodated in the sealed container 24.

  In the second power storage device of the present embodiment, terminal 22a of unit cell 22 arranged at one end of the stack of unit cells 22 constitutes the first terminal. Further, the terminal 22b of the unit cell 22 arranged at the other end of the stacked body of the unit cells 22 constitutes a second terminal. Discharge occurs when the voltage between the first terminal 22a and the second terminal 22b becomes higher than a predetermined upper limit voltage. A discharge can be generated in the discharge region 51 inside the sealed container 24. Thus, even in a power storage device including a plurality of unit cells 22, overcharging and the like can be suppressed by forming a discharge region in the sealed container to cause discharge. Moreover, since discharge occurs outside the plurality of unit cells 22, it is possible to suppress an excessive voltage from being applied to the power storage units inside each unit cell 22.

  FIG. 15 is a schematic cross-sectional view of the third power storage device in this embodiment. In the third power storage device, the first discharge electrode 37a connected to the terminal 22a of one unit cell 22 as the first terminal and the terminal 22b of the other unit cell 22 as the second terminal And a second discharge electrode 37b connected thereto. The distance between the first discharge electrode 37a and the second discharge electrode 37b is formed to be smaller than the distance between the terminal 22a as the first terminal and the terminal 22b as the second terminal. ing. In the second power storage device of the present embodiment, gas is ionized between the first discharge electrode 37a and the second discharge electrode 37b to cause discharge. A discharge region 51 is formed between the first discharge electrode 37a and the second discharge electrode 37b.

  When discharge occurs, heat and electromagnetic waves are generated. By arranging the discharge electrodes 37a and 37b inside the sealed container 24, it is possible to specify the place where the discharge occurs. It can suppress that the heat and electromagnetic waves which generate | occur | produce at the time of discharge exert a bad influence on the cell 22. Further, by disposing the discharge electrodes 37 a and 37 b, the unit cell 22 can be disposed at an arbitrary position inside the sealed container 24. Alternatively, many unit cells 22 can be arranged or stacked. For this reason, the energy density of the power storage device can be improved.

  The distance between the discharge electrode 37a and the discharge electrode 37b is a predetermined upper limit voltage based on the type of gas filled in the sealed container 24, the atmospheric pressure, the shape of the discharge electrode, the material of the discharge electrode, and the like. It is possible to set so as to generate a discharge.

  For example, a lithium ion battery that is sealed with an aluminum laminate film and overcharges when the voltage between terminals 22a and 22b of one single battery 22 is 5 V is prepared as the single battery 22. 38 lithium ion batteries are connected in series and accommodated in the sealed container 24 to form a power storage device. Further, the inside of the sealed container 24 is filled with 2 atmospheres of dry argon. The unit cell 22 can be pressurized by filling the inside of the sealed container 24 with the pressurized gas. In addition, the first discharge electrode and the second discharge electrode are arranged in the form of parallel plate electrodes inside the sealed container 24, and the distance between the first discharge electrode and the second discharge electrode is about 7. Set to 9 μm.

  For example, when a voltage of about 192 V is applied between the terminal 22a and the terminal 22b to the power storage device, a discharge occurs between the discharge electrodes 37a and 37b, and the terminal 22a and the terminal 22b It can suppress that an excessive voltage is applied between them. In addition, overcharge of the power storage device can be suppressed. That is, since it can suppress that a voltage larger than about 5V is applied to one single cell, overcharge can be suppressed.

  The battery cell outer body in the present embodiment is formed of a material that can be deformed when pressure is applied from the outside, but is not limited to this form, and employs a material that does not deform even when pressure is applied from the outside. It doesn't matter. Further, the container of the power storage device in this embodiment is formed so that the inside can be hermetically sealed, but is not limited to this form, and any container that can form an atmosphere of gas that causes discharge around the unit cell. Can be adopted.

  The single battery in the present embodiment has been described by taking a lithium ion battery as an example, but is not limited to this form, and any battery can be employed as long as it is a secondary battery. In addition, the lithium ion battery in the present embodiment exemplifies an all-solid battery in which the electrolyte is solid. However, the lithium ion battery is not limited to this form, and even if the electrolyte disposed between the positive electrode layer and the negative electrode layer is liquid. I do not care. Further, a separator or the like may be disposed between the positive electrode layer and the negative electrode layer.

  Other configurations, operations, and effects are the same as those in the first embodiment, and thus description thereof will not be repeated here.

  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 exterior body 24 sealed container 30 positive electrode layer 31 negative electrode layer 32 electrolyte layer 33, 33a, 33b current collector 35 battery element 36 connecting member 37a, 37b discharge electrode 38 laminate 40 charge / discharge circuit 50 Ionized gas 51 Discharge area

Claims (8)

An all-solid type unit cell in which a power storage unit including a plurality of battery elements is housed in an exterior body
The inside of the exterior body is filled with an inert gas,
The power storage unit includes a first conductive member and a second conductive member having a lower potential than the first conductive member,
When the voltage between the first conductive member and the second conductive member becomes larger than a predetermined upper limit voltage, the gas is ionized inside the exterior body so that a discharge is generated. A single battery characterized by being made. A first discharge electrode connected to the first conductive member;
A second discharge electrode connected to the second conductive member,
The distance between the first discharge electrode and the second discharge electrode is formed to be smaller than the distance between the first conductive member and the second conductive member,
When the voltage between the first conductive member and the second conductive member becomes larger than a predetermined upper limit voltage, a discharge is generated between the first discharge electrode and the second discharge electrode. The single battery according to claim 1, wherein   The unit cell according to claim 1 or 2, wherein the gas filled in the exterior body includes at least one of argon, helium, neon, krypton, xenon, and nitrogen. A battery that includes a power storage unit that can be charged, an exterior body that houses the power storage unit, and a terminal that protrudes from the exterior body;
A container containing at least one unit cell therein,
The inside of the container is filled with inert gas,
The terminal of the unit cell includes a first terminal and a second terminal having a lower potential than the first terminal,
When the voltage between the first terminal and the second terminal becomes larger than a predetermined upper limit voltage, the gas is ionized inside the container so that a discharge is generated. A power storage device is characterized. A first discharge electrode connected to the first terminal;
A second discharge electrode connected to the second terminal,
The distance between the first discharge electrode and the second discharge electrode is formed to be smaller than the distance between the first terminal and the second terminal,
A discharge is generated between the first discharge electrode and the second discharge electrode when the voltage between the first terminal and the second terminal is higher than a predetermined upper limit voltage. Item 5. The power storage device according to Item 4. With multiple cells
The power storage device according to claim 4 or 5, wherein a terminal on the positive electrode side of one unit cell constitutes a first terminal and a terminal on the negative electrode side of another unit cell constitutes a second terminal. The container includes an airtight container that is formed to be airtight,
The exterior body of the unit cell is formed to be deformable by applying pressure from the outside,
The power storage device according to any one of claims 4 to 6, wherein the gas filled in the sealed container is pressurized so as to be greater than atmospheric pressure.   The power storage device according to any one of claims 4 to 7, wherein the gas filled in the container that accommodates the unit cell includes at least one of argon, helium, neon, krypton, xenon, and nitrogen. .

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