Container for energy storage devices

Abstract

To provide a container for a power storage device, such as a transport container when a single or a plurality of power storage devices are wrapped and transported or moved, or a storage container when a single or a plurality of power storage devices are wrapped and stored, which can reduce the risk of fire spreading to the outside of the container at the time of abnormality such as breakage of the power storage device or a high-temperature environment.SOLUTION: The electric storage device container of the present embodiment has a structure in which a foam-molded article of a thermally depolymerizable polymer is disposed in a space between a container main body and a region for housing an electric storage device in the container main body for housing the electric storage device.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a container for a power storage device, such as a transport container for transporting and moving while wrapping a power storage device such as a lithium-ion battery, a lithium-ion capacitor, an electric double-layer capacitor, etc., or a storage container for storing while wrapping these power storage devices. Particularly, it relates to a container for a power storage device capable of reducing the risk of spreading combustion outside the container even when ignition occurs during abnormal conditions such as breakage of the power storage device or high-temperature environment.

Background Art

[0002] In recent years, power storage devices such as secondary batteries, lithium-ion capacitors, and electric double-layer capacitors, in which a power storage device using a non-aqueous electrolyte is housed in a casing, are used as power sources for high-output portable devices and electric vehicles.

[0003] Such a power storage device usually has a defined upper limit voltage and is controlled not to exceed the upper limit voltage in combination with an appropriate protection circuit. However, when the protection circuit malfunctions and exceeds the upper limit voltage, when charging and discharging are repeated, or when a short circuit occurs due to external factors, etc., the power storage device falls into an overcharged state, the electrolytic solution reacts with the electrode material, etc., and gas is generated, and the internal pressure rises due to this generated gas. This generated gas may contain flammable gases such as electrolytic solution, methane, carbon monoxide, ethylene, ethane, propane, etc., and when released outside the power storage device, there is a risk of causing ignition, explosion, etc.

[0004] In recent years, there has been a growing demand for higher output and larger capacity in energy storage devices such as lithium-ion capacitors and electric double-layer capacitors. As a result, there are increasing opportunities to use large currents in individual energy storage devices and in module configurations where multiple energy storage devices are stacked. For example, in a module with multiple energy storage devices stacked together, if one energy storage device becomes overcharged, even after the gas is released along with the electrolyte, the other energy storage devices may continue to function and supply a large current. This can lead to severe overheating due to short circuits, increasing the risk of ignition and explosion as described above.

[0005] As a technology to prevent such energy storage devices from catching fire, for example, a method has been proposed in which gas generated inside the lithium-ion battery is absorbed by a flammable gas absorbent to prevent the battery from rupturing (Patent Documents 1, 2).

[0006] On the other hand, a method has been proposed to reduce the temperature of the gas released to the outside when the safety valve opens due to an increase in internal pressure caused by gas generation inside the lithium-ion battery by placing a fire extinguishing agent inside the battery (Patent Document 3). Furthermore, a method has been proposed to prevent ignition caused by gas generated from lithium-ion batteries by placing a non-flammable gas, an aqueous solvent, or a porous material in which a non-flammable solvent is adsorbed in the pores and on the surface inside the lithium-ion battery (Patent Document 4). [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2001-155790 [Patent Document 2] Japanese Patent Publication No. 2003-077549 [Patent Document 3] Japanese Patent Publication No. 2010-287488 [Patent Document 4] Japanese Patent Publication No. 2013-187089 [Overview of the project] [Problems that the invention aims to solve]

[0008] However, in the event of electrical abnormalities or thermal runaway, a large amount of gas is instantaneously generated. Therefore, methods of placing gas adsorbents inside energy storage devices, as described in Patent Documents 1 and 2, are insufficient in terms of both gas adsorption amount and gas adsorption rate for the limited space of an energy storage device, and thus cannot completely suppress gas ejection from the energy storage device. Furthermore, as described in Patent Documents 3 and 4, methods of placing fire extinguishing agents or materials that adsorb non-combustible gases or aqueous solvents or non-combustible solvents inside an energy storage device to lower the internal temperature of a lithium-ion battery have the problem that if the amount of gas adsorbed is insufficient, the effect will not be fully realized, and gas ejection cannot be completely suppressed.

[0009] The present invention has been made in view of the above problems, and aims to provide a container for energy storage devices, such as a transport container for transporting or moving one or more energy storage devices encased in an external container, or a storage container for storing one or more energy storage devices encased in an external container, which can reduce the risk of fire spreading to the outside of the container in the event of damage to the energy storage device or abnormal conditions such as high temperature environments. [Means for solving the problem]

[0010] To solve the above problems, the present invention provides a container for an energy storage device in which a foamed molded body of a thermodepolymer is placed in the gap between the energy storage device and the container body that houses the energy storage device (Invention 1). In particular, in the above invention (Invention 1), it is preferable that the energy storage device uses a non-aqueous electrolyte (Invention 2).

[0011] According to the inventions described above (Inventions 1 and 2), by placing a foamed molded body of a thermopolymerizable polymer in the space between the energy storage device and the container for the energy storage device, the risk of fire spreading to the outside of the container for the energy storage device in the event of damage to the energy storage device or abnormal conditions such as high temperatures can be reduced.

[0012] In the above invention (Invention 1), it is preferable that the foamed molded article of the thermally depolymerizable polymer contains 10% by weight or more of the thermally depolymerizable polymer (Invention 3). In the above invention (Invention 1), it is preferable that the foamed molded article of the thermally depolymerizable polymer is a foamed molded article of a polymer (homopolymer or polymer of two or more components) using one or more of methyl methacrylate (MMA), α-methylstyrene (AMS), and tetrafluoroethylene (TFE) as monomer components (Invention 4).

[0013] According to these inventions (inventions 3 and 4), it is possible to effectively prevent the spread of fire to the outside of the container when an abnormality occurs in the energy storage device.

[0014] In the above invention (Invention 1), it is preferable that the foamed molded article of the pyropolymerizable polymer is in the form of a sheet or a plate (Invention 5). In the above invention (Invention 5), it is preferable that the sheet-like or plate-like foamed molded article has a thickness of 1 mm to 100 mm (Invention 6). In particular, in the above invention (Invention 6), it is preferable that the density of the sheet-like or plate-like foamed molded article is 18 g to 20 g / L (Invention 7).

[0015] According to the inventions described above (inventions 5 to 7), by placing a sheet-like or plate-like foamed molded body of a predetermined thickness and density in the gap between it and the container for the energy storage device, it is possible to effectively prevent the spread of fire to the outside of the container when a malfunction occurs in the energy storage device.

[0016] In the above inventions (Inventions 1 to 7), multiple energy storage devices may be stacked (Invention 8).

[0017] In the above invention (Invention 8), in the case where an abnormality occurs in one of the power storage devices in a power storage device stack in which a plurality of power storage devices are stacked, even if a combustible gas jets out from the power storage device and flows out into the space of the container, the material of the foamed molded body of the thermally depolymerizable polymer affects the combustible gas, so that the risk of fire spreading outside the container can be significantly reduced. Therefore, it can be particularly preferably applied to the power storage device stack.

Advantages of the Invention

[0018] In the container for a power storage device of the present invention, since the foamed molded body of the thermally depolymerizable polymer is arranged in the gap between the power storage device and the container body, the thermally depolymerizable polymer affects the high-temperature ejecta and ejected gas released from the power storage device due to a short circuit or the like of the power storage device, so that the risk of ignition of the container for a power storage device can be significantly reduced.

Embodiments for Carrying Out the Invention

[0019] The container for a power storage device of the present invention will be described in detail based on the following embodiments.

[0020] [Container for Power Storage Device] The container for a power storage device of the present embodiment has a structure in which a foamed molded body of a thermally depolymerizable polymer is arranged in the gap between the region where the power storage device is accommodated and the container body in the container body for accommodating the power storage device.

[0021] (Power Storage Device) In this embodiment, the power storage device is not particularly limited, and either a primary battery or a secondary battery can be used, but a secondary battery is preferred. The type of this secondary battery is not particularly limited. For example, a lithium-ion battery, a lithium-ion polymer battery, an all-solid-state battery, a lead-acid battery, a nickel-hydrogen storage battery, a nickel-cadmium storage battery, a nickel-iron storage battery, a nickel-zinc storage battery, a silver oxide-zinc storage battery, a metal-air battery, a polyvalent cation battery, a capacitor, a capacitor, etc. can be used. Among these, those using a non-aqueous electrolyte can be preferably used. Among these secondary batteries, as a suitable application target for the battery materials of the present invention, a lithium-ion battery, a lithium-ion polymer battery, a lithium-ion capacitor, an all-solid-state battery, etc. can be preferably used.

[0022] As the non-aqueous electrolyte, for example, a mixed solution of a cyclic carbonate such as propylene carbonate (PC) and ethylene carbonate (EC) and a chain carbonate such as dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) can be used. Further, the non-aqueous electrolyte may be a solution in which a lithium salt such as lithium hexafluorophosphate is dissolved as an electrolyte, if necessary. For example, a mixed solution obtained by mixing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a ratio of 1:1:1, or a mixed solution obtained by mixing propylene carbonate (PC), ethylene carbonate (EC), and diethyl carbonate (DEC) in a ratio of 1:1:1, to which 1 mol / L of lithium hexafluorophosphate is added, can be used.

[0023] The power storage device as described above may be in the form of a power storage device stack in which a plurality of them are stacked.

[0024] (Container body for power storage device) In this embodiment, the container body is not particularly limited as long as it can enclose the above-mentioned energy storage device (energy storage device stack) with air gaps, and can be made of various materials such as corrugated cardboard, synthetic resin, or metal. The container body is generally rectangular in shape, but is not limited to this. Preferably, the container body is provided with a release valve or release hole so that if an abnormality occurs in the energy storage device, the ejected gas or ejected material released from the energy storage device can be released to the outside of the container.

[0025] (Flame-resistant material) In this embodiment, a foamed molded body of a thermopolymerizable polymer is placed in the gap between the energy storage device and the container body as an ignition prevention material.

[0026] (Thermolytic polymer) In this embodiment, a thermally depolymerizable polymer is a polymer that has the property of depolymerizing into monomers by heat or light, and leaves no residue when heated. Examples of the above thermally depolymerizable polymer include a polymer (homopolymer or polymer with two or more components) that uses one or more of methyl methacrylate (MMA), α-methylstyrene (AMS), and tetrafluoroethylene (TFE) as monomer components as a base polymer. Among these, a polymer using methyl methacrylate (MMA) and α-methylstyrene (AMS) as monomer components is preferred, or a polymer composed of methyl methacrylate (MMA):α-methylstyrene (AMS) in a molar ratio of 5:95 to 95:5 may be used, and furthermore, a polymer obtained by polymerizing these with other monomer components (monomers such as styrene) added during polymerization may also be used. Such thermally depolymerizable polymers can significantly reduce the risk of fire in containers for energy storage devices due to a mechanism in which they thermally decompose and generate monomers when exposed to high-temperature ejected materials or gases released from energy storage devices due to short circuits or other issues.

[0027] (Foam molded articles of pyrolytic polymers) In this embodiment, the foamed molded article of the above-mentioned pyropolymerizable polymer can be produced using one or more of methyl methacrylate (MMA), α-methylstyrene (AMS), and tetrafluoroethylene (TFE) as monomer components, using a known method (for example, the method described in Japanese Patent Application Publication No. 2007-314774).

[0028] The foamed molded article of the above-mentioned pyromreparable polymer may contain any suitable additives as needed. Examples of such additives include crosslinking agents, tackifiers, plasticizers (e.g., trimellitic acid ester plasticizers, pyromellitic acid ester plasticizers, etc.), pigments, dyes, fillers, antioxidants, conductive materials, antistatic agents, ultraviolet absorbers, light stabilizers, release modifiers, softeners, surfactants, flame retardants, antioxidants, and the like.

[0029] Furthermore, it is possible to add known fire extinguishing agent components to the foamed molded body, and it is also possible to use the known fire extinguishing agent by sandwiching it between the foamed molded bodies.

[0030] In this embodiment, there are no particular restrictions on the shape of the foamed molded body of the fire-preventing material placed in the gap between the energy storage device and the container. However, considering ease of handling when installing it in the gap between the energy storage device and the container, it is preferable to have a sheet or plate shape. In the case of a sheet or plate-shaped foamed molded body, a thickness of 1 mm to 100 mm, and particularly 10 mm to 80 mm, is preferable in terms of handling and cost-effectiveness. Furthermore, the density of the foamed molded body, especially the sheet or plate-shaped foamed molded body, is preferably about 18 g to 20 g / L.

[0031] Furthermore, these fire-preventing materials can also be used with materials that provide cooling effects through heat transfer and absorption, suppression of combustion radical reactions, and flame-extinguishing effects that destabilize flames on the surface of the adsorbent, in response to ejected materials and gases from energy storage devices.

[0032] The fire-preventing materials described above may be used individually or in combination of two or more materials.

[0033] [How to use containers for energy storage devices] The energy storage device and container described above may be transported or stored by first installing a foam molded body of fire-preventing material in the container body, then housing an energy storage device with, for example, a state of charge (SOC) of about 30%, sealing the container, or by housing the energy storage device in the container body, then installing a foam molded body of fire-preventing material in the gaps, sealing the container, and then transporting or storing it.

[0034] By housing and transporting or storing an energy storage device in a container of this embodiment, even if the energy storage device ignites due to a short circuit caused by external factors or if it is left in a high-temperature environment, the presence of a foamed molded body made of fire-preventing material prevents the spread of fire within the container, thus reducing the risk of fire spreading outside the container.

[0035] The present invention has described the container for energy storage devices as described above. However, the present invention only requires that a foamed molded body of a thermopolymerizable polymer be placed in the gap between the energy storage device (energy storage device stack) and the container body, and there are no particular restrictions on the size, shape, etc. of the energy storage device (energy storage device stack). Therefore, it can be applied to energy storage devices (energy storage device stacks) of a wide range of sizes, from smartphones to automotive applications, and is applicable to various applications. [Examples]

[0036] The present invention will be described in more detail based on the following specific examples, but the present invention is not limited to the following examples.

[0037] [Manufacturing of foamed molded articles of pyrolytic polymers] In this embodiment, the foamed molded article of the pyropolymerizable polymer was manufactured by the following method based on the method described in Japanese Patent Application Publication No. 2007-314774.

[0038] A unit with a stirring device and an internal volume of 1 m³ 3In the autoclave, 430 kg of deionized water, 0.4 kg of tricalcium phosphate (manufactured by Taihei Chemical Industry Co., Ltd.) as a suspension agent, 70 g of disodium dodecyldiphenyl ethersulfonate (manufactured by Kao Corporation: Perex SSH 50% aqueous solution) as a surfactant, and 0.65 kg of sodium acetate as an electrolyte were added. Next, 1.5 kg of benzoyl peroxide (manufactured by Nippon Oil & Fats Co., Ltd.: Niper BW, water-diluted powder) and 0.4 kg of t-butyl peroxy-2-ethylhexyl monocarbonate (manufactured by Nippon Oil & Fats Co., Ltd.: Perbutyl E) were dissolved as polymerization initiators, 3.1 kg of liquid paraffin (manufactured by MORESCO Corporation: Moresco White P60, average carbon number 20) as a networking agent, and 0.6 kg of α-methylstyrene dimer (manufactured by Nippon Oil & Fats Co., Ltd.: Nofmer MSD) as a chain transfer agent in 233 kg of methyl methacrylate, 56 kg of styrene, and 22 kg of α-methylstyrene. This mixture was then added to an autoclave while stirring at 110 rpm. After purging the autoclave with nitrogen, heating was started and the temperature was raised to 80°C over 1.5 hours. During the heating process to 80°C, when the temperature reached 60°C, 0.8 kg of a 0.02% aqueous solution of potassium persulfate was added as a suspension aid. After reaching 80°C, the temperature was further increased to 115°C over 6 hours, held at 115°C for 5 hours, and then cooled to 30°C over approximately 6 hours. During the heating process from 80°C to 115°C, when the temperature reached 110°C, 37 kg of pentane (a mixture of 80% n-pentane and 20% isopentane) was added to the autoclave over approximately 60 minutes as a blowing agent. After adding the blowing agent, the stirring speed was reduced to 90 rpm. After cooling, the contents were removed, nitric acid was added to dissolve the tricalcium phosphate adhering to the surface of the foamed acrylic resin particles, then dewatered and washed using a centrifuge, and moisture adhering to the surface was removed using an air-flow dryer to obtain foamed acrylic resin particles with an average particle size of approximately 0.8 mm. The obtained foamed acrylic resin particles were sieved to separate particles with a diameter of 0.5 to 1.2 mm. To 100 parts by weight of these foamed acrylic resin particles, 0.015 parts by weight of N,N-bis(2-hydroxyethyl)alkylamine, an antistatic agent, was added, and the mixture was further coated with a mixture of 0.2 parts by weight of zinc stearate and 0.1 parts by weight of glycerin monostearate.12.5 kg of the obtained foamed acrylic resin particles were heated in a pressurized batch foaming machine (Daisen Kogyo Co., Ltd.: DYH850) by supplying steam to maintain an internal pressure of 0.01 MPa (gauge pressure) within the machine, and the steam pressure was maintained for approximately 80 seconds until the bulk density was approximately 20 kg / m³. 3 Foamed particles of acrylic resin were obtained.

[0039] The obtained foamed particles were placed in a maturation silo and matured at room temperature for one day. Block molding was then performed using a block molding machine (Daisen Kogyo Co., Ltd.: VS-2000-5VMC). The mold dimensions were 2.0m (length) x 1.0m (width) x 0.5m (thickness). Heating and demolding control were performed using a surface pressure gauge installed in the center of the 2.0m x 1.0m surface of the mold. Heating steam was supplied into the mold to heat the foamed acrylic resin particles until the foaming pressure reached a maximum surface pressure of 0.098MPa. After that, water cooling was performed for 3 seconds, and then the pressure inside the mold cavity was reduced to -0.06MPa (gauge pressure). The reduced pressure state was maintained until the surface pressure gauge read 0.00MPa (gauge pressure), after which the mold was opened and the block-shaped foamed molded body was removed. The density of the obtained foamed molded body was approximately 19g / L.

[0040] [Nail-piercing test] (Comparative Example 1) A PP resin container (internal dimensions: 80mm wide x 105mm long x 34mm deep, resin thickness 2mm, with the electrode side of an aluminum laminate lithium-ion battery positioned on the 80mm wide side of the PP resin container, and with five 10mm diameter holes on the 80mm wide side of the container, and an open top) was prepared for use as an internal container for an energy storage device. A 1500mAh aluminum laminate lithium-ion battery (35mm wide x 75mm long) with a positive electrode ternary system was placed inside this PP resin container in a fully charged state, and a 4mm thick PP resin plate was placed over it to cover it, sealing the edges of the cover with heat-resistant tape to prevent any gaps, so that ejected material from the lithium-ion battery during a nail-piercing test would only be released through the five holes on the top.

[0041] A PP resin container intended as the inner container for this energy storage device was placed on the outside of another PP resin container intended as a transport or storage container (internal dimensions: 98mm wide x 148mm long x 48mm deep, resin thickness 2mm, with five 10mm diameter holes on the 98mm side and an open top (the holes are drilled on the opposite side from the holes in the PP resin container intended as the energy storage device container)). A 4mm thick PP resin plate was then used as a lid, and the edges of the lid were sealed with heat-resistant tape to prevent any gaps. This ensured that any battery ejection during a nail-piercing test would only be released through the five holes, thus creating an energy storage device container.

[0042] When a nail-piercing test was conducted on this energy storage device container, the battery was destroyed and a violent fire was observed outside the container.

[0043] (Example 1) In the energy storage device container used in Comparative Example 1, a plate-shaped molded body (3 mm thick, 19 g / LL density) of the acrylic resin foam molded body obtained above, as a foam molded body of a thermopolymerizable polymer, was applied to the upper inner surface of the PP resin plate of the lid of a PP resin container intended as a casing, at a depth of 0.011 m 2 It was then attached with double-sided tape to create a container for an energy storage device.

[0044] When a nail-piercing test was performed on this energy storage device container under the same conditions as in Comparative Example 1, the battery was destroyed, but no ignition was observed outside the container.

[0045] [Overcharge test] To simulate the scenario in which the energy storage device stored in this container catches fire for some reason, we performed an evaluation by overcharging the energy storage device inside UN cardboard and steel containers.

[0046] (Comparative Example 2) A UN cardboard box [product number] 4GV-23 / 17 (internal dimensions: 325mm x 245mm x 300mmH, external dimensions: 340mm x 265mm x 335mmH) was assembled with cloth tape, and a 3200mAh laminated lithium-ion battery with a positive electrode ternary system was placed inside.

[0047] When this energy storage device container was overcharged at 15V, 9.6A, the battery was destroyed after approximately 19 minutes, and a violent fire was observed on the outside of the energy storage device container.

[0048] (Example 2) In the energy storage device container used in Comparative Example 2, a plate-shaped molded body (310 mm × 230 mm × 50 mm H) of the acrylic resin foam molded body obtained above was placed on the bottom surface of the energy storage device container as a foam molded body of a thermally depolymerizable polymer. A laminate-type lithium-ion battery with a ternary positive electrode and a capacity of 3200 mAh was placed on top of it, and then another plate-shaped molded body (310 mm × 230 mm × 50 mm H) of the acrylic resin foam molded body was placed on top of that.

[0049] When this energy storage device container was overcharged at 15V, 9.6A, the battery was destroyed, but no fire was observed outside the container.

[0050] (Comparative Example 3) A 3200mAh laminated lithium-ion battery was placed inside a steel container constructed from 1.6mm thick flat plates (internal dimensions: 300mm x 300mm x 300mmH). (Comparative Example 3) When this energy storage device container was overcharged at 15V, 9.6A, the battery was destroyed after approximately 19 minutes, and a fierce fire was observed outside the container through a gap in the energy storage device.

[0051] (Example 3) In the energy storage device container used in Comparative Example 3, a plate-shaped molded body (300 mm × 300 mm × 20 mm H) of the acrylic resin foam molded body obtained above as a thermally depolymerizable polymer was attached to the six inner surfaces of the energy storage device container, a laminate-type lithium-ion battery with a 3200 mAh positive electrode ternary system was placed on the bottom surface, and a plate-shaped molded body (250 mm × 250 mm × 50 mm H) of the acrylic resin foam molded body was placed on top of it.

[0052] When this energy storage device container was overcharged at 15V, 9.6A, the battery was destroyed, but no fire was observed outside the container.

Claims

1. A foamed molded body of a thermopolymerizable polymer is placed in the gap between the energy storage device and the container body that houses the energy storage device. The foamed molded article of the pyropolymer is in the form of a sheet or a plate. The aforementioned sheet-like or plate-like foamed molded body has a thickness of 1 mm to 100 mm. A container for an energy storage device, wherein the density of the sheet-like or plate-like foamed molded body is 18 g to 20 g / L.

2. The container for an energy storage device according to claim 1, wherein the energy storage device uses a non-aqueous electrolyte.

3. The container for an energy storage device according to claim 1, wherein the foamed molded article of the thermally depolymerizable polymer contains 10% by weight or more of the thermally depolymerizable polymer.

4. The container for an energy storage device according to claim 1, wherein the foamed molded article of the thermally depolymerizable polymer is a foamed molded article of a polymer (homopolymer or copolymer of two or more components) using one or more of methyl methacrylate (MMA), α-methylstyrene (AMS), and tetrafluoroethylene (TFE) as monomer components.

5. A container for an energy storage device according to any one of claims 1 to 4, wherein a plurality of the energy storage devices are stacked.