JP2016031360A - Hermetic secondary battery deformation detection sensor, hermetic secondary battery, and hermetic secondary battery deformation detection method - Google Patents

Abstract

A deformation detection sensor, a sealed secondary battery, and a sealed secondary for a sealed secondary battery that can detect deformation of the sealed secondary battery due to swelling of a single cell with high sensitivity and have excellent heat dissipation. To provide a battery deformation detection method. A deformation detection sensor for a sealed secondary battery includes a polymer matrix layer and a detection unit, and the polymer matrix layer changes an external field according to deformation of the polymer matrix layer. A deformation detection sensor for a sealed secondary battery that contains a filler in a dispersed manner, the detection unit detects a change in the external field, and the polymer matrix layer further contains a thermally conductive filler in addition to the filler. . [Selection] Figure 2

Description

  The present invention relates to a sensor for detecting deformation of a sealed secondary battery, a sealed secondary battery to which the sensor is attached, and a method for detecting deformation of the sealed secondary battery.

  In recent years, sealed secondary batteries represented by lithium ion secondary batteries (hereinafter sometimes referred to simply as “secondary batteries”) are not only mobile devices such as mobile phones and laptop computers, but also electric vehicles and hybrids. It is also used as a power source for electric vehicles such as cars. A single battery (cell) that constitutes a secondary battery includes an electrode group in which a positive electrode and a negative electrode are wound or stacked with a separator interposed therebetween, and an outer package that houses the electrode group. In general, a laminate film or a metal can is used as an exterior body, and an electrode group is accommodated together with an electrolytic solution in an enclosed space.

  The secondary battery is used in the form of a battery module or a battery pack including a plurality of single cells in an application where a high voltage is required, such as the power source for an electric vehicle described above. In the battery module, a plurality of single cells connected in series are accommodated in a housing, and, for example, four single cells are connected in two parallel two series or four series. In addition, in the battery pack, various devices such as a controller are accommodated in the casing in addition to the plurality of battery modules connected in series. In a secondary battery used as a power source for an electric vehicle, a battery pack housing is formed in a shape suitable for in-vehicle use.

  Such a secondary battery has a problem that when the electrolytic solution is decomposed due to overcharge or the like, the single battery swells as the internal pressure increases due to the decomposition gas, and the secondary battery is deformed. In that case, if the charging current or discharging current is not stopped, it will ignite and the secondary battery will burst as the worst result. Therefore, in order to prevent the secondary battery from bursting, it is important to detect the deformation of the secondary battery due to the swelling of the single cell with high sensitivity so that the charging current and the discharging current can be stopped in a timely manner.

  Patent Document 1 describes a method of forming a sensor insertion space in a battery module in order to attach a temperature sensor for detecting the temperature of the single battery in a battery module having a plurality of single batteries. However, in the method using such a temperature sensor, since a space for mounting the temperature sensor is separately provided, the volume of the secondary battery is pressed more than necessary.

  Further, in Patent Document 2, a strain gauge is bonded to the surface of a cell case (an example of an exterior body), and a change in resistance value of the strain gauge according to the swelling of the case is detected, so that A method for reducing the charging or discharging current is described. However, in such a technique using a strain gauge, there is a risk that the sensor characteristics may vary due to the displacement of the strain gauge due to vibration and the stability may be deteriorated particularly when used for a long period of time.

JP 2013-171697 A JP 2006-128062 A

  By the way, since a lithium ion secondary battery etc. have especially high energy density, it generate | occur | produces not only at the time of abnormality but at the time of normal charging / discharging. Therefore, from the viewpoint of preventing heat storage due to heat generation, it is a fact that the market demands to improve the heat dissipation of the secondary battery.

  The present invention has been made in view of the above circumstances, and its purpose is to detect deformation of a sealed secondary battery due to swelling of a single cell with high sensitivity and to deform a sealed secondary battery excellent in heat dissipation. An object of the present invention is to provide a detection sensor, a sealed secondary battery, and a deformation detection method for the sealed secondary battery.

  The above object can be achieved by the present invention as described below. That is, the present invention provides a deformation detection sensor for a sealed secondary battery, comprising a polymer matrix layer and a detection unit, and the polymer matrix layer changes in the external field according to the deformation of the polymer matrix layer. The filler is dispersed and contained, the detection unit detects a change in the external field, and the polymer matrix layer further contains a thermally conductive filler in addition to the filler. The present invention relates to a deformation detection sensor for a secondary battery.

  The polymer matrix layer is mounted so as to be sandwiched between the unit cells and the housing that houses the unit cells, for example, between the unit cells adjacent to each other. Alternatively, the battery module is sandwiched between the battery module housing included in the battery pack and the battery module housing adjacent to the battery module housing, and further, in the gap between the battery module housing and the battery pack housing. Is done. In any case, the polymer matrix layer may be attached in a compressed state.

  When the secondary battery is deformed by the swelling of the unit cell, the polymer matrix layer is deformed accordingly. A detection part detects the change of the external field accompanying the deformation | transformation of the polymer matrix layer. Thereby, the deformation of the secondary battery can be detected with high sensitivity. The polymer matrix layer attached as described above does not compress the volume of the secondary battery and suppresses displacement due to vibration or the like, thereby stabilizing the sensor characteristics.

  In particular, the polymer matrix layer constituting the deformation detection sensor of the sealed secondary battery according to the present invention further contains a heat conductive filler in addition to the filler that changes the external field according to the deformation. For this reason, even if a secondary battery heat | fever-generates, it is excellent in heat dissipation.

  In the deformation detection sensor for a sealed secondary battery according to the present invention, the polymer matrix layer contains a magnetic filler as the filler, and the detection unit detects a change in the magnetic field as the external field. preferable. According to this configuration, it is possible to detect a change in the magnetic field accompanying the deformation of the polymer matrix layer without wiring. In addition, since a Hall element having a wide sensitivity region can be used as the detection unit, highly sensitive detection can be performed over a wider range.

  In the deformation detection sensor of the sealed secondary battery, the polymer matrix layer has the magnetic filler unevenly distributed in the thickness direction, and the concentration of the magnetic filler in the secondary battery side region in the thickness direction is the thickness. It is preferable that it is higher than the direction of the detection unit side in the direction. According to such a configuration, deformation of the sealed secondary battery due to the swelling of the single battery can be detected with higher sensitivity.

  In the deformation detection sensor of the sealed secondary battery, the specific gravity of the heat conductive filler is preferably lower than the specific gravity of the magnetic filler, and the average particle diameter of the heat conductive filler is 0.5 to 50 μm. It is more preferable. According to this configuration, the magnetic filler tends to be unevenly distributed in one direction in the thickness direction of the polymer matrix layer. For this reason, by arranging the polymer matrix layer so that the side where the magnetic filler is unevenly distributed becomes the secondary battery side, the deformation of the sealed secondary battery due to the swelling of the single battery can be detected with higher sensitivity.

  The sealed secondary battery according to the present invention is provided with the above-described deformation detection sensor, and may be a single battery module or a battery pack including a plurality of battery modules. In such a sealed secondary battery, deformation due to swelling of the single battery is detected with high sensitivity by a deformation detection sensor. Nevertheless, the volume of the secondary battery is not compressed by the deformation detection sensor, and the sensor characteristics become stable.

  The deformation detection method for a sealed secondary battery according to the present invention is the deformation detection method for a sealed secondary battery, wherein a polymer matrix layer is mounted in a gap of the sealed secondary battery, and the polymer matrix layer Contains a filler that changes the external field according to deformation of the polymer matrix layer, and further contains a thermally conductive filler in addition to the filler. A change in the external field due to deformation is detected, and deformation of the sealed secondary battery is detected based on the change.

  The polymer matrix layer is mounted in the gap of the sealed secondary battery. When the secondary battery is deformed by the swelling of the cell, the polymer matrix layer is deformed accordingly, and the deformation of the secondary battery is detected by detecting the change in the external field accompanying the deformation of the polymer matrix layer. It can be detected with high sensitivity. In particular, in the present invention, the polymer matrix layer contains a thermally conductive filler in addition to a filler that changes the external field according to its deformation. Not only can deformation be detected with high sensitivity, it also has excellent heat dissipation.

A perspective view schematically showing an example of a battery module Sectional drawing which shows typically the AA arrow cross section of FIG.

  Hereinafter, embodiments of the present invention will be described.

  The battery module 1 shown in FIGS. 1 and 2 has a plurality of single cells 2 inside a casing 11. In the present embodiment, four unit cells 2 are connected in series (for example, 2 parallel 2 series or 4 series). Although not shown in detail, the unit cell 2 includes an electrode group in which a positive electrode and a negative electrode are wound or laminated with a separator interposed therebetween, and an exterior body that houses the electrode group. In the sealed space inside the exterior body, the electrode group is accommodated together with the electrolytic solution. A laminate film such as an aluminum laminate foil is used for the outer package of the unit cell 2, but a cylindrical or square metal can may be used instead.

  The battery module 1 is a lithium ion secondary battery that can be used as a power source for an electric vehicle, and is mounted on the vehicle in the form of a battery pack. In the battery pack, a plurality of battery modules 1 connected in series are accommodated in a casing together with various devices such as a controller. The casing of the battery pack is formed in a shape suitable for in-vehicle use, for example, a shape that matches the underfloor shape of the vehicle. In the present invention, the sealed secondary battery is not limited to a non-aqueous electrolyte secondary battery such as a lithium ion battery, and may be an aqueous electrolyte secondary battery such as a nickel metal hydride battery.

  As shown in FIG. 2, a deformation detection sensor is attached to the sealed secondary battery, and the deformation detection sensor includes a polymer matrix layer 3 and a detection unit 4. The polymer matrix layer 3 is affixed to the surface of the unit cell 2 (the outer surface of the exterior body), and an adhesive or an adhesive tape is used for the affixation as necessary. The polymer matrix layer 3 is formed in a sheet shape, and is disposed in a gap in the secondary battery, for example, between the unit cell 2 and the casing 11 that houses the cell. However, although not shown in the present invention, it can also be attached to the corners of the unit cell 2 or the casing 11 by folding the polymer matrix layer 3 in the gap between the unit cells 2 adjacent to each other. It is.

  The polymer matrix layer 3 contains a filler that disperses the external field according to deformation of the polymer matrix layer 3 in a dispersed manner. The detection unit 4 detects a change in the external field. The detection unit 4 is disposed away from the polymer matrix layer 3 to the extent that changes in the external field can be detected, and is preferably affixed to a relatively firm location that is not easily affected by the swelling of the unit cell 2. In the present embodiment, the detection unit 4 is affixed to the outer surface of the casing 11, but the present invention is not limited thereto, and the detection unit 4 may be affixed to the inner surface of the casing 11 or the casing of the battery pack. These cases are formed of, for example, metal or plastic, and a laminate film may be used for the case of the battery module.

  The polymer matrix layer 3 shown in FIG. 2 is sandwiched and mounted in a compressed state between the unit cell 2 and the casing 11 that accommodates it. The thickness of the polymer matrix layer 3 in an uncompressed state is larger than the gap G2 in which the polymer matrix layer 3 is disposed, and the polymer matrix layer 3 is compressed in the thickness direction.

  When the unit cell 2 swells, the polymer matrix layer 3 is deformed accordingly, and a change in the external field accompanying the deformation of the polymer matrix layer 3 is detected by the detection unit 4. The detection signal output from the detection unit 4 is sent to a control device (not shown), and when a change in the external field exceeding a set value is detected by the detection unit 4, the switching (not shown) connected to the control device. The circuit cuts off power and stops charging or discharging current. In this way, the deformation of the secondary battery due to the swelling of the unit cell 2 is detected with high sensitivity, and the secondary battery is prevented from bursting. This deformation detection sensor does not compress the volume of the secondary battery, and the sensor characteristics are stabilized by suppressing the positional deviation.

  In the example of FIG. 2, one polymer matrix layer 3 and one detection unit 4 are shown, but a plurality of them may be used according to various conditions such as the shape and size of the secondary battery. At that time, a plurality of polymer matrix layers 3 are affixed to the same unit cell 2, or a plurality of detectors 4 are configured to detect changes in the external field due to deformation of the same polymer matrix layer 3. Also good.

  In this embodiment, the polymer matrix layer 3 contains a magnetic filler as the filler, and the detection unit 4 detects a change in the magnetic field as the external field. In this case, the polymer matrix layer 3 is preferably a magnetic elastomer layer in which a magnetic filler is dispersed in a matrix made of an elastomer component.

  Examples of the magnetic filler include rare earth-based, iron-based, cobalt-based, nickel-based, and oxide-based materials, but a rare earth-based material that can obtain higher magnetic force is preferable. The shape of the magnetic filler is not particularly limited, and may be spherical, flat, needle-like, columnar, or indefinite. The average particle size of the magnetic filler is preferably 0.02 to 500 μm, more preferably 0.1 to 400 μm, and still more preferably 0.5 to 300 μm. When the average particle size is smaller than 0.02 μm, the magnetic properties of the magnetic filler tend to be lowered, and when the average particle size exceeds 500 μm, the mechanical properties of the magnetic elastomer layer tend to be lowered and become brittle.

  The magnetic filler may be introduced into the elastomer after magnetization, but is preferably magnetized after being introduced into the elastomer. Magnetization after introduction into the elastomer facilitates control of the polarity of the magnet and facilitates detection of the magnetic field.

  The polymer matrix constituting the deformation detection sensor according to the present invention further contains a thermally conductive filler in addition to a filler that changes the external field according to the deformation of the polymer matrix layer, preferably a magnetic filler. Is a feature. By further containing a thermally conductive filler, the heat dissipation of the polymer matrix layer is improved. In order to impart sufficient heat dissipation to the polymer matrix layer, the amount of the thermally conductive filler is 1 to 300 parts by weight with respect to 100 parts by weight of the polymer (elastomer) component constituting the polymer matrix layer. Is more preferable, and it is more preferable that it is 3-200 weight part. Moreover, in order to ensure sufficient heat dissipation of the polymer matrix layer, the thermal conductivity of the polymer matrix layer is preferably 0.5 W / mK or more, more preferably 0.6 W / mK or more. preferable.

  Specific examples of the thermally conductive filler include oxide particles such as aluminum oxide, silicon dioxide, titanium dioxide, mica, potassium titanate, iron oxide, and talc, and nitrides such as boron nitride, silicon nitride, and aluminum nitride. Material particles, carbide particles such as silicon carbide, metal particles such as silver, copper, and aluminum, and carbon compounds such as carbon nanotubes and carbon black.

  In order to make the magnetic filler unevenly distributed in one direction in the thickness direction of the polymer matrix layer, the specific gravity of the heat conductive filler is preferably lower than the specific gravity of the magnetic filler. The specific gravity difference is more preferably 2 or more, further preferably 3 or more, and particularly preferably 4 or more. From the same viewpoint, the average particle size of the thermally conductive filler is preferably 0.3 to 300 μm, more preferably 0.4 to 200 μm, and particularly preferably 0.5 to 50 μm.

  On the other hand, as the polymer matrix, for example, an elastomer component can be used, and any elastomer component can be used. As the elastomer component, a thermoplastic elastomer, a thermosetting elastomer, or a mixture thereof can be used. Examples of the thermoplastic elastomer include a styrene thermoplastic elastomer, a polyolefin thermoplastic elastomer, a polyurethane thermoplastic elastomer, a polyester thermoplastic elastomer, a polyamide thermoplastic elastomer, a polybutadiene thermoplastic elastomer, a polyisoprene thermoplastic elastomer, A fluororubber-based thermoplastic elastomer can be used. Examples of the thermosetting elastomer include polyisoprene rubber, polybutadiene rubber, styrene-butadiene rubber, polychloroprene rubber, nitrile rubber, ethylene-propylene rubber and other diene synthetic rubbers, ethylene-propylene rubber, butyl rubber, acrylic rubber, Non-diene synthetic rubbers such as polyurethane rubber, fluorine rubber, silicone rubber, epichlorohydrin rubber, and natural rubber can be mentioned. Among these, a thermosetting elastomer is preferable because it can suppress the sag of the magnetic elastomer accompanying heat generation and overload of the battery. More preferred is polyurethane rubber (also referred to as polyurethane elastomer) or silicone rubber (also referred to as silicone elastomer).

  The polyurethane elastomer is obtained by reacting an active hydrogen-containing compound with an isocyanate component. When using a polyurethane elastomer as an elastomer component, an active hydrogen-containing compound and a magnetic filler are mixed, and an isocyanate component is mixed therein to obtain a mixed solution. Moreover, a liquid mixture can also be obtained by mixing a magnetic filler with an isocyanate component and mixing an active hydrogen-containing compound. A magnetic elastomer can be produced by casting the mixed solution into a mold subjected to a release treatment, and then curing by heating to a curing temperature. When a silicone elastomer is used as an elastomer component, a magnetic elastomer can be produced by adding a magnetic filler to a silicone elastomer precursor, mixing it, putting it in a mold, and then heating and curing it. In addition, you may add a solvent as needed.

  As the isocyanate component that can be used in the polyurethane elastomer, compounds known in the field of polyurethane can be used. For example, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 2,2′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, 4,4′-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, p-phenylene Aromatic diisocyanates such as diisocyanate, m-phenylene diisocyanate, p-xylylene diisocyanate, m-xylylene diisocyanate, aliphatic diisocyanates such as ethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 1,6-hexamethylene diisocyanate 1,4-cyclohexane diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, isophorone diisocyanate, nor It can be mentioned alicyclic diisocyanates such as Renan diisocyanate. These may be used alone or in combination of two or more. The isocyanate component may be modified such as urethane modification, allophanate modification, biuret modification, and isocyanurate modification. Preferred isocyanate components are 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4'-diphenylmethane disissocyanate, more preferably 2,4-toluene diisocyanate, 2,6-toluene diisocyanate.

  In the present invention, compounds known in the field of polyurethane can be used as the active hydrogen-containing compound. For example, polytetramethylene glycol, polypropylene glycol, polyethylene glycol, polyether polyols typified by copolymers of propylene oxide and ethylene oxide, polybutylene adipates, polyethylene adipates, and 3-methyl-1,5-pentane adipates Polyester polyol such as polyester polyol, polycaprolactone polyol, reaction product of polyester glycol and alkylene carbonate such as polycaprolactone, and the like. Polyester polycarbonate polyol reacted with dicarboxylic acid, esterification of polyhydroxyl compound and aryl carbonate High molecular weight polyol polycarbonate polyols obtained by the reaction can be mentioned. These may be used alone or in combination of two or more.

  In addition to the high molecular weight polyol component described above as the active hydrogen-containing compound, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, 3-methyl-1,5-pentanediol, diethylene glycol, triethylene glycol, 1,4-bis (2-hydroxyethoxy) benzene, trimethylolpropane, glycerin, 1,2,6- Hexanetriol, pentaerythritol, tetramethylolcyclohexane, methylglucoside, sorbitol, mannitol, dulcitol, sucrose, 2,2,6,6-tetrakis (hydroxymethyl) cyclohexanol, and triethanolamine Low molecular weight polyol component equal, ethylenediamine, tolylenediamine, diphenylmethane diamine, may be used low molecular weight polyamine component of diethylenetriamine. These may be used alone or in combination of two or more. Furthermore, 4,4′-methylenebis (o-chloroaniline) (MOCA), 2,6-dichloro-p-phenylenediamine, 4,4′-methylenebis (2,3-dichloroaniline), 3,5-bis ( Methylthio) -2,4-toluenediamine, 3,5-bis (methylthio) -2,6-toluenediamine, 3,5-diethyltoluene-2,4-diamine, 3,5-diethyltoluene-2,6- Diamine, trimethylene glycol-di-p-aminobenzoate, polytetramethylene oxide-di-p-aminobenzoate, 1,2-bis (2-aminophenylthio) ethane, 4,4'-diamino-3,3 ' -Diethyl-5,5'-dimethyldiphenylmethane, N, N'-di-sec-butyl-4,4'-diaminodiphenylmethane, 4,4'-diamy −3,3′-diethyldiphenylmethane, 4,4′-diamino-3,3′-diethyl-5,5′-dimethyldiphenylmethane, 4,4′-diamino-3,3′-diisopropyl-5,5′- Dimethyldiphenylmethane, 4,4′-diamino-3,3 ′, 5,5′-tetraethyldiphenylmethane, 4,4′-diamino-3,3 ′, 5,5′-tetraisopropyldiphenylmethane, m-xylylenediamine, Polyamines exemplified by N, N′-di-sec-butyl-p-phenylenediamine, m-phenylenediamine, p-xylylenediamine and the like can also be mixed. Preferred active hydrogen-containing compounds are polytetramethylene glycol, polypropylene glycol, a copolymer of propylene oxide and ethylene oxide, 3-methyl-1,5-pentane adipate, more preferably a copolymer of polypropylene glycol, propylene oxide and ethylene oxide. It is a coalescence.

  When using a polyurethane elastomer, the NCO index is preferably 0.3 to 1.2, more preferably 0.35 to 1.1, and still more preferably 0.4 to 1.05. When the NCO index is smaller than 0.3, the magnetic elastomer tends to be insufficiently cured. When the NCO index is larger than 1.2, the elastic modulus increases and the sensor sensitivity tends to decrease.

  The amount of the magnetic filler in the magnetic elastomer is preferably 1 to 450 parts by weight, more preferably 2 to 400 parts by weight with respect to 100 parts by weight of the elastomer component. If it is less than 1 part by weight, it tends to be difficult to detect a change in the magnetic field, and if it exceeds 450 parts by weight, the magnetic elastomer itself may become brittle.

  For example, a magnetoresistive element, a Hall element, an inductor, an MI element, a fluxgate sensor, or the like can be used as the detection unit 4 that detects a change in the magnetic field. Examples of the magnetoresistive element include a semiconductor compound magnetoresistive element, an anisotropic magnetoresistive element (AMR), a giant magnetoresistive element (GMR), and a tunnel magnetoresistive element (TMR). Among these, the Hall element is preferable because it is useful as the detection unit 4 having high sensitivity over a wide range.

  The thickness of the polymer matrix layer 3 in an uncompressed state is preferably 300 to 3000 μm, more preferably 400 to 2000 μm, and still more preferably 500 to 1500 μm. When the thickness is smaller than 300 μm, the handling property tends to be deteriorated due to brittleness when a required amount of filler is added. On the other hand, when the thickness is larger than 3000 μm, the polymer matrix layer 3 is excessively compressed and hardly deformed when disposed in the gap as described above, and the sensor sensitivity may be lowered.

  The polymer matrix layer 3 may be a non-foamed body that does not contain bubbles, but may be a foam containing bubbles from the viewpoint of improving stability and sensor sensitivity, and further from the viewpoint of weight reduction. Good. A general resin foam can be used for the foam, but it is preferable to use a thermosetting resin foam in consideration of characteristics such as compression set. Examples of the thermosetting resin foam include a polyurethane resin foam and a silicone resin foam. Among these, a polyurethane resin foam is preferable. The above-mentioned isocyanate component and active hydrogen-containing compound can be used for the polyurethane resin foam.

  As the catalyst used for the polyurethane resin foam, a known catalyst can be used without limitation, but triethylenediamine (1,4-diazabicyclo [2,2,2] octane), N, N, N ′, N ′. -Tertiary amine catalysts such as tetramethylhexanediamine and bis (2-dimethylaminoethyl) ether, and metal catalysts such as tin octylate, lead octylate, zinc octylate, and bismuth octylate can be used. These may be used alone or in combination of two or more.

  As commercial products of the above-mentioned catalyst, “TEDA-L33” manufactured by Tosoh Corporation, “NIAX CATALYST A1” manufactured by Momentive Performance Materials, “Caorizer NO.1”, “Kaorizer NO.30P” manufactured by Kao Corporation. "DABCO T-9" manufactured by Air Products, "BTT-24" manufactured by Toei Chemical Co., "Pucat 25" manufactured by Nippon Chemical Industry Co., Ltd., and the like.

  As a foam stabilizer used for a polyurethane resin foam, what is used for manufacture of a normal polyurethane resin foam, such as a silicone type foam stabilizer and a fluorine type foam stabilizer, can be used, for example. The silicone-based surfactant and fluorine-based surfactant used as the silicone-based foam stabilizer and the fluorine-based foam stabilizer have a polyurethane-soluble part and an insoluble part in the molecule. The insoluble part uniformly disperses the polyurethane material and lowers the surface tension of the polyurethane system, so that bubbles are easily generated and are hard to break. Of course, if the surface tension is too low, bubbles are not easily generated. Become. In the resin foam of the present invention, for example, when the silicone surfactant is used, the dimethylpolysiloxane structure as the insoluble part can reduce the cell diameter or increase the number of cells. It becomes.

Examples of commercially available silicone foam stabilizers include “SF-2962”, “SRX 274DL”, “SF-2965”, “SF-2904”, “SF-2908” manufactured by Toray Dow Corning, "SF-2904", "L5340", Evonik Degussa AG of "Tegosutabu ^{(Tegostab R) B8017, B-} 8465, B-8443 " and the like. Moreover, as a commercial item of the said fluorine-type foam stabilizer, "FC430", "FC4430" by 3M company, "FC142D", "F552", "F554", "F558" by Dainippon Ink & Chemicals, Inc. are mentioned, for example. ”,“ F561 ”,“ R41 ”, and the like.

  The blending amount of the foam stabilizer is preferably 1 to 15 parts by mass, more preferably 2 to 12 parts by mass with respect to 100 parts by mass of the resin component. If the blending amount of the foam stabilizer is less than 1 part by mass, foaming is not sufficient, and if it exceeds 15 parts by mass, bleeding may occur.

  The foam content of the foam forming the polymer matrix layer 3 is preferably 20 to 80% by volume. When the bubble content is 20% by volume or more, the polymer matrix layer 3 is flexible and easily deformed, and the sensor sensitivity can be improved satisfactorily. Further, when the bubble content is 80% by volume or less, embrittlement of the polymer matrix layer 3 is suppressed, and handling properties and stability are improved. The bubble content is calculated based on the specific gravity measured in accordance with JIS Z-8807-1976, and the specific gravity value of the non-foamed material.

  The average cell diameter of the foam forming the polymer matrix layer 3 is preferably 50 to 300 μm. The average opening diameter of the foam is preferably 15 to 100 μm. When the average bubble diameter is less than 50 μm or the average opening diameter is less than 15 μm, the stability of the sensor characteristics tends to deteriorate due to an increase in the amount of the foam stabilizer. On the other hand, when the average bubble diameter exceeds 300 μm or the average opening diameter exceeds 100 μm, the contact area with a single cell to be detected tends to decrease and stability tends to decrease. The average bubble diameter and the average opening diameter were determined by observing the cross section of the polymer matrix layer with a SEM at a magnification of 100 times, and using the image analysis software for the obtained image, all the bubbles present in the arbitrary range of the cross section The bubble diameter and the opening diameter of all open bubbles are measured and calculated from the average value.

  The closed cell ratio of the foam forming the polymer matrix layer 3 is preferably 5 to 70%. Thereby, excellent stability can be exhibited while ensuring ease of compression of the polymer matrix layer 3. Moreover, it is preferable that the volume fraction of the filler (this embodiment magnetic filler) with respect to the foam which forms the polymer matrix layer 3 is 1-30 volume%.

The polyurethane resin foam described above can be produced by an ordinary method for producing a polyurethane resin foam except that it contains a magnetic filler. The method for producing a polyurethane resin foam containing the magnetic filler includes, for example, the following steps (i) to (v).
(I) Step of forming isocyanate group-containing urethane prepolymer from polyisocyanate component and active hydrogen component (ii) Mixing and pre-stirring the isocyanate group-containing urethane prepolymer, foam stabilizer, catalyst and magnetic filler, and non-reacting A primary stirring step of vigorously stirring so as to take in bubbles in a natural gas atmosphere (iii) a step of further adding an active hydrogen component and secondary stirring to prepare a cell-dispersed urethane composition containing a magnetic filler (iv) A step of forming the urethane-dispersed urethane composition into a desired shape and curing to produce a urethane resin foam containing a magnetic filler. (V) A step of magnetizing the urethane resin foam to form a magnetic urethane resin foam.

  As a method for producing a polyurethane resin foam, a chemical foaming method using a reactive foaming agent such as water is known. However, an isocyanate group-containing urethane prepolymer such as steps (ii) and (iii) described above, It is preferable to use a mechanical foaming method in which a mixture containing a foaming agent, a catalyst and a magnetic filler and an active hydrogen component are mechanically stirred in a non-reactive gas atmosphere. According to the mechanical foaming method, the molding operation is simpler than the chemical foaming method, and water is not used as the foaming agent. Therefore, the molded product has tough and excellent resilience (restorability) with fine bubbles. Is obtained.

  First, an isocyanate group-containing urethane prepolymer is formed from a polyisocyanate component and an active hydrogen component as in the step (i), and an isocyanate group-containing urethane prepolymer and a foam stabilizer as in the primary stirring step (ii). Then, the catalyst and the magnetic filler are mixed, pre-stirred, and vigorously stirred so as to take in bubbles in a non-reactive gas atmosphere, and the active hydrogen component is further added as in the secondary stirring step (iii). Stir vigorously to prepare a cell-dispersed urethane composition containing a magnetic filler. In the polyurethane resin foam containing the polyisocyanate component, the active hydrogen component and the catalyst as in the above steps (i) to (iv), the method of forming the polyurethane resin foam after forming the isocyanate group-containing urethane prepolymer in advance is as follows. It is known to those skilled in the art, and the production conditions can be appropriately selected depending on the compounding material.

  As the formation conditions of the above step (i), first, the blending ratio of the polyisocyanate component and the active hydrogen component is the ratio of the isocyanate group in the polyisocyanate component to the active hydrogen group in the active hydrogen component (isocyanate group / active hydrogen). Group) is selected to be 1.5 to 5, preferably 1.7 to 2.3. The reaction temperature is preferably 60 to 120 ° C., and the reaction time is preferably 3 to 8 hours. Furthermore, conventionally known urethanization catalysts and organic catalysts such as lead octylate commercially available from Toei Chemical Co., Ltd. under the trade name “BTT-24”, “TEDA-L33” manufactured by Tosoh Corporation, Momentive Performance Material "NIAX CATALYST A1" manufactured by FUJITSU LIMITED, "Caorizer No. 1" manufactured by Kao Corporation, "DABCO T-9" manufactured by Air Products, and the like may be used. As an apparatus used in the step (i), any apparatus can be used as long as it can react by stirring and mixing the above materials under the above-described conditions, and an apparatus used for ordinary polyurethane production can be used. it can.

  Examples of the method of performing the primary stirring in the step (ii) include a method using a general mixer capable of mixing a liquid resin and a filler, and examples thereof include a homogenizer, a dissolver, and a planetary mixer.

  In the step (ii), the foam stabilizer is added to the isocyanate group-containing urethane prepolymer side and stirred (primary stirring), and in the step (iii), the active hydrogen component is further added and the secondary stirring is performed. It is preferable because bubbles taken into the reaction system are difficult to escape and efficient foaming can be performed.

  The non-reactive gas in the step (ii) is preferably a non-flammable gas, and specifically, nitrogen, oxygen, carbon dioxide gas, helium, argon and other rare gases, and mixed gases thereof are exemplified, and dried to moisture. It is most preferable to use air from which air has been removed. Further, the conditions for the primary stirring and the secondary stirring, particularly the primary stirring, can be used at the time of urethane foam production by a normal mechanical foaming method, and are not particularly limited. Using a mixer, the mixture is vigorously stirred for 1 to 30 minutes at a rotational speed of 1000 to 10,000 rpm. Examples of such an apparatus include a homogenizer, a dissolver, and a mechanical floss foaming machine.

  In the step (iv), the method of forming the cell-dispersed urethane composition into a desired shape such as a sheet is not particularly limited. For example, a batch type in which the mixed solution is injected into a mold subjected to a release treatment and cured. A molding method or a continuous molding method in which the cell-dispersed urethane composition is continuously supplied and cured on a release-treated face material can be used. Also, the curing conditions are not particularly limited, and preferably from 60 to 200 ° C. for 10 minutes to 24 hours. If the curing temperature is too high, the resin foam is thermally deteriorated, the mechanical strength is deteriorated, and the curing temperature is If it is too low, curing failure of the resin foam will occur. On the other hand, if the curing time is too long, the resin foam is thermally deteriorated and mechanical strength is deteriorated. If the curing time is too short, the resin foam is poorly cured.

  In the step (v), the method of magnetizing the magnetic filler is not particularly limited, and a commonly used magnetizing apparatus, for example, “ES-10100-15SH” manufactured by Electromagnetic Industry Co., Ltd., “TM” manufactured by Tamagawa Manufacturing Co., Ltd. -YS4E "or the like. Usually, a magnetic field having a magnetic flux density of 1 to 3T is applied. The magnetic filler may be added in the step (ii) for forming the magnetic filler dispersion after magnetization, but from the viewpoint of handling workability of the magnetic filler in the intermediate step, the magnetic filler is added in the step (v). It is preferable to magnetize.

  In the present embodiment, as described above, the polymer is sandwiched between the unit cells 2 adjacent to each other as shown in FIG. 2 or between the unit cell 2 and the housing 11 that houses the unit cell as shown in FIG. The matrix layer 3 is mounted in a compressed state. When the unit cell 2 expands and the polymer matrix layer 3 is deformed, a change in the external field accompanying the deformation of the polymer matrix layer 3 is detected, and the deformation of the secondary battery is detected based on the change.

  The present invention is not limited to the embodiment described above, and various improvements and modifications can be made without departing from the spirit of the present invention.

  In the above-described embodiment, the example in which the polymer matrix layer 3 is sandwiched in the gap between the unit cell 2 and the casing 11 (see FIG. 2) is shown, but the present invention is not limited to this. For example, the polymer matrix layer may be sandwiched between the casing of a battery module included in the battery pack and the casing of the adjacent battery module, that is, within the gap between the casings of adjacent battery modules. In particular, it is useful in a battery module of a laminate film type. Alternatively, the polymer matrix layer may be sandwiched in the gap between the battery module housing and the battery pack housing.

  In the above-described embodiment, an example in which a change in a magnetic field is used has been described. However, a configuration in which a change in another external field such as an electric field is used may be used. For example, the polymer matrix layer may contain conductive fillers such as metal particles, carbon black, and carbon nanotubes as fillers, and the detector may detect changes in the electric field (changes in resistance and dielectric constant) as external fields. It is done.

  In the present invention, a sealing material may be provided to such an extent that the flexibility of the polymer matrix layer is not impaired. As the sealing material, a thermoplastic resin, a thermosetting resin, or a mixture thereof can be used. Examples of the thermoplastic resin include styrene-based thermoplastic elastomers, polyolefin-based thermoplastic elastomers, polyurethane-based thermoplastic elastomers, polyester-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, polybutadiene-based thermoplastic elastomers, polyisoprene-based thermoplastic elastomers, Fluorine-based thermoplastic elastomer, ethylene / ethyl acrylate copolymer, ethylene / vinyl acetate copolymer, polyvinyl chloride, polyvinylidene chloride, chlorinated polyethylene, fluororesin, polyamide, polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polybutadiene Etc. Examples of the thermosetting resin include polyisoprene rubber, polybutadiene rubber, styrene / butadiene rubber, polychloroprene rubber, diene-based synthetic rubber such as acrylonitrile / butadiene rubber, ethylene / propylene rubber, ethylene / propylene / diene rubber, butyl rubber, Non-diene rubbers such as acrylic rubber, polyurethane rubber, fluorine rubber, silicone rubber, epichlorohydrin rubber, natural rubber, polyurethane resin, silicone resin, epoxy resin and the like can be mentioned.

  Examples of the present invention will be described below, but the present invention is not limited thereto.

The following raw materials were used for the production of the magnetic polyurethane elastomer to be the polymer matrix layer.
TDI-80: Toluene diisocyanate (Mitsui Chemicals, 2,4-body = 80%, Cosmonate T-80)
Polyol A: polyoxypropylene glycol obtained by adding propylene oxide to glycerol as an initiator, OHV56, functional group number 3 (EX-3030, manufactured by Asahi Glass Co., Ltd.).
Polyol B: Polyoxypropylene glycol obtained by adding propylene oxide to propylene glycol as an initiator, OHV56, number of functional groups 2 (Asahi Glass Co., Ltd., EX-2020).
Nd—Fe—B fine powder: MF-15P (average particle size: 133 μm, specific gravity 7.5, manufactured by Aichi Steel Corporation)
Aluminum nitride: WJB (average particle size: 1.5 μm, specific gravity 3.3, manufactured by Toyo Aluminum Co., Ltd.)
Aluminum nitride: W15 (average particle size: 15 μm, specific gravity 3.3, manufactured by Toyo Aluminum Co., Ltd.)
Silver: Ag-HWQ (average particle size 5 μm, specific gravity 10.5, manufactured by Fukuda Metal Foil Powder Industry Co., Ltd.)
Lead octylate: BTT-24 (manufactured by Toei Chemical Company)

  Moreover, the prepolymer A shown in Table 1 was used for the prepolymer.

Example 1
In a reaction vessel, 42.6 parts by weight of polyol A (polyoxypropylene glycol obtained by adding propylene oxide to glycerol as an initiator, OH value 56, number of functional groups 3, manufactured by Asahi Glass Co., Ltd., EX-3030) and polyol B (glycerol) Polyoxypropylene glycol with propylene oxide added to the initiator, OH value 56, number of functional groups 2, 42.6 parts by weight, manufactured by Asahi Glass Co., Ltd., EX-2020) was added, and dehydration under reduced pressure was performed for 1 hour with stirring. Thereafter, the inside of the reaction vessel was purged with nitrogen. Then, 14.8 parts by weight of toluene diisocyanate (Mitsui Chemicals, 2,4 = 80%, Cosmonate T-80) was added to the reaction vessel, and the temperature in the reaction vessel was maintained at 80 ° C. 3 By reacting for a period of time, isocyanate-terminated prepolymer A (NCO% = 3.58%) was synthesized.

  Next, Nd-Fe-B fine powder (Aichi Steel Co., Ltd.) was added to a mixed solution of 213.1 parts by weight of polyol A, 0.65 part by weight of lead octylate (manufactured by Toei Chemical Co., Ltd., BTT-24) and 62.6 parts by weight of toluene. Manufactured, MF-15P, average particle size 133 μm) 670.9 parts by weight and aluminum nitride (Toyo Aluminum Co., Ltd., WJB, average particle size 1.5 μm) 147.6 parts by weight were added to prepare a filler dispersion. 100.0 parts by weight of the above prepolymer A degassed under reduced pressure was added to this filler dispersion, and mixed and defoamed with a rotation / revolution mixer (manufactured by Sinky) to prepare a urethane composition containing a magnetic filler. . This urethane composition was dropped onto a release-treated PET film having a 1.0 mm spacer and adjusted to a thickness of 1.0 mm with a nip roll. Then, it left still at room temperature for 5 minutes, the uneven distribution process was performed, and it hardened | cured at 80 degreeC for 1 hour, and obtained the polyurethane resin containing a magnetic filler. The obtained polyurethane resin was magnetized at 2.0 T with a magnetizing apparatus (manufactured by Electronic Magnetic Industry Co., Ltd.) to obtain a magnetic polyurethane resin. The formulation and production conditions are shown in Table 2. In Table 2, “Battery side” and “Sensor side” shown in the “Arrangement” item are those when the deformation detection sensor of the sealed secondary battery is manufactured using the obtained polymer matrix layer, respectively. The high concentration surface of the magnetic filler (that is, the region that is unevenly distributed in the thickness direction) is either the battery side (secondary battery region) or the sensor side (detection unit side region).

Examples 2-5, Comparative Example 1
Based on the formulation and production conditions in Table 2, a magnetic polyurethane resin was obtained in the same manner as in Example 1.

(Measurement of thermal conductivity)
The thermal conductivity was measured by a heat flow meter method according to JISA 1412-2 in the thickness direction of a sample of 100 mm long × 100 mm wide × 10 mm thick. The above-mentioned thermal conductivity measuring device was evaluated for performance using a device produced by combining a heat flow meter (manufactured by Eto Electric: M55A, 2300A) and a rubber heater (Samcon 230, SBX3030K1S).

(Filler uneven distribution rate)
A cross section (thickness: 1.0 mm) of the produced magnetic polyurethane resin was obtained by scanning electron microscope-energy dispersive X-ray analyzer (SEM-EDS) (SEM: S-3500N manufactured by Hitachi High-Technologies Corporation, EDS: Horiba) Using an EMAX model 7021-H) manufactured by Seisakusho, observation was performed at a magnification of 100 times under the conditions of an acceleration voltage of 25 kV, a degree of vacuum of 50 Pa, and a WD of 15 mm. Then, the abundance of Fe element specific to the magnetic filler was determined by elemental analysis of the entire thickness direction and two regions whose sections were equally divided in the thickness direction. For this abundance, the ratio of the region on the opposite side of the detection portion to the entire region in the thickness direction was calculated, and this was used as the magnetic filler uneven distribution rate.
Further, the amount of Al element (aluminum element) in the magnetic polyurethane resin is obtained in the same manner, and the ratio of the region on the side opposite to the detection portion to the region in the entire thickness direction is calculated for this amount of the presence, This was made into the thermal conductive filler uneven distribution rate.

(Evaluation of sensor characteristics)
It cut out to the magnitude | size of the produced magnetic polyurethane resin (size: 10 mm x 10 mm), and affixed on the stainless steel plate with the double-sided tape (Sekisui Chemical Co., Ltd. make, double tack tape # 5782). A pressure was applied to the test piece using a surface indenter having a size of 20 mm × 20 mm, and the change in magnetic flux density relative to the initial value was measured (the number of tests was n = 5). The table shows changes in magnetic flux density when the strain amount is 10%. It shows that the sensitivity as a sensor is so high that this value is large.

  From the results in Table 2, it can be seen that the deformation detection sensor of the sealed secondary battery including the polymer matrix layers according to Examples 1 to 5 can detect the deformation of the secondary battery with high sensitivity and is excellent in heat dissipation. .

DESCRIPTION OF SYMBOLS 1 Battery module 2 Single cell 3 Polymer matrix layer 4 Detection part 6 Container 11 Case

Claims (7)

In a deformation detection sensor for a sealed secondary battery,
A polymer matrix layer and a detector;
The polymer matrix layer contains dispersed fillers that change the external field according to deformation of the polymer matrix layer, and the detection unit detects the change in the external field,
The polymer matrix layer further contains a heat conductive filler in addition to the filler, and the deformation detection sensor for a sealed secondary battery. The polymer matrix layer contains a magnetic filler as the filler,
The deformation detection sensor for a sealed secondary battery according to claim 1, wherein the detection unit detects a change in a magnetic field as the external field.   In the polymer matrix layer, the magnetic filler is unevenly distributed in the thickness direction, and the concentration of the magnetic filler in the secondary battery side region in the thickness direction is higher than that in the detection portion side region in the thickness direction. A deformation detection sensor for a sealed secondary battery according to claim 2.   The deformation detection sensor for a sealed secondary battery according to claim 2 or 3, wherein the specific gravity of the thermally conductive filler is lower than the specific gravity of the magnetic filler.   The deformation detection sensor for a sealed secondary battery according to any one of claims 2 to 4, wherein the thermal conductive filler has an average particle size of 0.5 to 50 µm.   A sealed secondary battery to which the deformation detection sensor according to any one of claims 1 to 5 is attached. In a method for detecting deformation of a sealed secondary battery,
A polymer matrix layer is mounted in the gap of the sealed secondary battery,
The polymer matrix layer contains dispersed fillers that change the external field according to deformation of the polymer matrix layer, and further contains a thermally conductive filler in addition to the fillers,
A method for detecting deformation of a sealed secondary battery, comprising: detecting a change in the external field accompanying deformation of the polymer matrix layer, and detecting deformation of the sealed secondary battery based on the change.

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