JP6310805B2 - Sealed secondary battery deformation detection sensor and manufacturing method thereof, sealed secondary battery, and deformation detection method of sealed secondary battery - Google Patents

Description

  The present invention relates to a sensor for detecting deformation of a sealed secondary battery, a method for manufacturing the same, 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 the secondary battery repeatedly expands and contracts when it is repeatedly charged and discharged, the small deformation, which is different from the large deformation seen at the time of abnormality, occurs even when it is normal. Therefore, there is a demand in the market for a deformation detection sensor for a secondary battery that does not detect small deformations seen during normal operation but detects only large deformations found during abnormal operation with a high sensitivity. Was the actual situation.

  The present invention has been made in view of the above circumstances, and its purpose is to detect a deformation of a sealed secondary battery that does not sense a small deformation seen in a normal state and can detect only a large deformation seen in an abnormal state with high sensitivity. It is another object of the present invention to provide a sealed secondary battery and a method for detecting deformation of 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 detection unit detects a change in the external field, and the polymer matrix layer is elastic in the inner region in the thickness direction as compared with the elastic modulus of the outer secondary battery side region in the thickness direction. The present invention relates to a deformation detection sensor for a sealed secondary battery characterized by having a high rate. In particular, the polymer matrix layer preferably contains a filler that disperses the external field according to deformation of the polymer matrix layer.

  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 has an elastic modulus in the inner region in the thickness direction compared to the elastic modulus in the outer secondary battery side region in the thickness direction. Designed to be high. That is, since the small deformation seen in the normal state is absorbed by the secondary battery side region of the polymer matrix layer on the outer side in the thickness direction having a low elastic modulus, the polymer matrix layer does not emit a sensor signal in the normal state. On the other hand, when the amount of strain deformation of the secondary battery is large (when the abnormality of the secondary battery occurs), the deformation of the secondary battery reaches the inner region in the thickness direction with a high elastic modulus, and the inside of the polymer matrix layer Since the amount of distortion deformation in the region increases, the generated sensor signal increases. As a result, the deformation detection sensor of the sealed secondary battery according to the present invention has a function of sensing only when an abnormality with a large deformation occurs without sensing when normal.

  In the deformation detection sensor of the sealed secondary battery, the polymer matrix layer preferably has an elastic modulus in an inner region in the thickness direction higher than an elastic modulus in both outer regions in the thickness direction. More preferably, the elastic modulus of the inner region in the thickness direction is higher by 1 MPa or more than the elastic modulus of the outer secondary battery side region in the thickness direction. In this case, the function of sensing only at the time of occurrence of an abnormality accompanied by large deformation is improved without sensing during normal operation.

  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. Preferably there is. 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 is one in which the filler is unevenly distributed in the thickness direction, and in both outer regions in the thickness direction compared to the inner region in the thickness direction. The filler concentration is preferably low. In this case, the function of sensing only at the time of occurrence of an abnormality accompanied by large deformation is further improved without sensing when normal.

  In the deformation detection sensor of the sealed secondary battery, the polymer matrix layer is preferably a laminated structure having at least two polymer matrix layers. In this case, it is possible to more easily manufacture a polymer matrix layer having a function of sensing only when an abnormality accompanied by a large deformation does not occur during normal operation.

  In the deformation detection sensor of the sealed secondary battery, at least two of the polymer matrix layers are both magnetized and stacked such that the magnetic poles have the same direction. preferable. In this case, the function of sensing only at the time of occurrence of an abnormality accompanied by large deformation is improved without sensing during normal operation. Further, when two magnetized polymer matrix layers are laminated so that the magnetic poles have the same direction, the interface between the two polymer matrix layers has different magnetic poles (for example, the upper layer) If the lower side is the S pole, the upper side of the lower layer is the N pole), and the upper layer and the lower layer are also bonded by magnetic force, so that the characteristic stability is excellent.

  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 sensor for a sealed secondary battery according to the present invention includes, for example, a first step of preparing a mixed solution by mixing a magnetic filler with a thermosetting elastomer precursor, and a second step of forming the mixed solution into a sheet shape. A step, a third step in which the magnetic filler is unevenly distributed in the thermosetting elastomer precursor, a fourth step in which the thermosetting elastomer precursor is heated and cured, and the magnetic filler is unevenly distributed by magnetizing the magnetic filler. It can be produced by a production method comprising a fifth step of forming the polymer matrix layer and a sixth step of laminating at least two polymer matrix layers in which the magnetic filler is unevenly distributed. In particular, when laminating the polymer matrix layers in the sixth step, when the self-adhesion is performed by heating at 70 to 130 ° C. for 0.5 to 3 hours, the flexibility of the polymer matrix layer is not impaired. It is preferable because a decrease in sensitivity can be prevented.

  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 Changes the external field according to the deformation of the polymer matrix layer, and the elastic modulus of the inner region in the thickness direction is larger than the elastic modulus of the outer secondary battery side region in the thickness direction. The change of the external field accompanying the deformation of the polymer matrix layer is detected, and the deformation of the sealed secondary battery is detected based on the change. In particular, regarding the polymer matrix layer, the polymer matrix layer preferably contains a filler that disperses the external field according to the deformation of the polymer matrix layer in a dispersed manner.

  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 elastic modulus of the inner region in the thickness direction is set to be higher than the elastic modulus of the outer secondary battery side region in the thickness direction. It has a function to sense only when an abnormality with deformation occurs. In order to further enhance this function, the polymer matrix layer preferably contains a magnetic filler as the filler, and the detection unit detects a change in the magnetic field as the external field.

A perspective view schematically showing an example of a battery module Sectional drawing which shows typically the AA arrow cross section of FIG. Sectional drawing which shows another example of the attachment location of a polymer matrix layer Sectional view showing the degree of uneven distribution of magnetic pole and filler of polymer matrix layer

  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 formed in a gap in the secondary battery, for example, in a gap between adjacent unit cells 2, a unit cell 2 as shown in FIG. It is arranged between. The polymer matrix layer 3 can be bent and attached to the corners of the unit cell 2 or the casing 11.

  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 mounted in a compressed state sandwiched in the gap. The thickness of the polymer matrix layer 3 in an uncompressed state is larger than the gap G1 in which the polymer matrix layer 3 is disposed, and the polymer matrix layer 3 is compressed in the thickness direction. The polymer matrix layer 3 shown in FIG. 3 is also sandwiched in the gap and mounted in a compressed state. In this example, the polymer matrix layer 3 is sandwiched in the gap between the unit cell 2 and the housing 11 and mounted in a compressed state. ing. 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 also 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 FIGS. 2 and 3, one polymer matrix layer 3 and one detection unit 4 are shown, but a plurality of them may be used depending on various conditions such as the shape and size of the secondary battery. Good. At that time, the polymer matrix layer 3 attached as shown in FIG. 2 and the polymer matrix layer 3 attached as shown in FIG. 3 may coexist. Further, a plurality of polymer matrix layers 3 may be attached to the same unit cell 2, or a plurality of detectors 4 may be configured to detect changes in the external field due to deformation of the same polymer matrix layer 3. Good.

  In the present embodiment, the polymer matrix layer 3 contains a magnetic filler as the filler, and the detection unit 4 detects a change in magnetic field as the external field, that is, a change in magnetic flux density. 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 is characterized in that the elastic modulus of the inner region in the thickness direction is higher than the elastic modulus of the outer secondary battery side region in the thickness direction. Since the polymer matrix layer is designed as described above, the deformation detection sensor according to the present invention does not sense small deformations that are seen in a normal state, and can detect only large deformations that are found in an abnormal state with high sensitivity. In particular, the polymer matrix layer preferably has an elastic modulus in the inner region in the thickness direction higher than the elastic modulus in both outer regions in the thickness direction, and the polymer matrix layer has an outer secondary battery side region in the thickness direction. It is more preferable that the elastic modulus of the inner region in the thickness direction is 1 MPa or more higher than the elastic modulus.

  As a method of designing the polymer matrix layer so that the elastic modulus of the inner region in the thickness direction is higher than the elastic modulus of the outer secondary battery side region in the thickness direction of the polymer matrix layer, For example, the polymer matrix layer is composed of a laminated structure having at least two polymer matrix layers, and at least two polymer matrix layers are both magnetized, and their magnetic poles The method of laminating | stacking so that direction may become the same is mentioned. That is, for example, the N pole of one magnetized polymer matrix layer and the S pole of the other magnetized polymer matrix layer may be laminated so as to face each other, You may laminate | stack so that the south pole of a polymer matrix layer and the north pole of the other polymer matrix layer magnetized may face each other. By laminating at least two magnetized polymer matrix layers so that the directions of the magnetic poles are the same, a deformation detection sensor having excellent characteristic stability can be obtained.

  In addition, in order to obtain a deformation detection sensor that has an improved function of sensing only when an abnormality with large deformation does not occur during normal operation, fillers are unevenly distributed in the thickness direction, compared to the inner region in the thickness direction. Thus, it is preferable to use a polymer matrix layer having a low filler concentration in both outer regions in the thickness direction. In such a polymer matrix layer, for example, in the thickness direction, the filler concentration in the other region is higher than that in one region, and two polymer matrix layers face each other in the region where the filler concentration is high. It can be formed by laminating.

  In the above, the filler uneven distribution ratio in a high filler concentration region in one polymer matrix layer is preferably more than 50, more preferably 60 or more, and further preferably 70 or more. In this case, the filler uneven distribution ratio in the region where the filler concentration is low is less than 50. The filler uneven distribution rate in a region with a high filler concentration is 100 at the maximum, and the filler uneven distribution rate in a region with a low filler concentration is 0 at a minimum. On the other hand, when two polymer matrix layers are laminated, a preferable range of the filler uneven distribution ratio in a region where the filler concentration is high is 30 to 50, assuming that the filler uneven distribution ratio of the entire laminate is 100. For the uneven distribution of the filler, after introducing the filler into the elastomer component, it can be allowed to stand at room temperature or at a predetermined temperature, and then spontaneously settled according to the weight of the filler, by changing the temperature and time of standing. The filler uneven distribution rate can be adjusted. The filler may be unevenly distributed using a physical force such as centrifugal force or magnetic force.

  The filler uneven distribution rate is measured by the following method. That is, the cross section of the polymer matrix layer is observed at 60 times using a scanning electron microscope-energy dispersive X-ray analyzer (SEM-EDS). The area of the entire cross section in the thickness direction and the four areas obtained by dividing the cross section into four in the thickness direction are each subjected to elemental analysis of filler-specific metal elements (for example, Fe element in the case of the magnetic filler of this embodiment). Find the abundance. For this abundance, the ratio of one area to the entire area in the thickness direction is calculated, and this is used as the filler uneven distribution rate in the one area. The filler uneven distribution rate in the other region is the same as this.

  The polymer matrix layer 3 may have a structure in which a region having a low filler concentration is formed of a foam containing bubbles. Thereby, the polymer matrix layer is further easily deformed and the sensor sensitivity is increased. Moreover, the area | region with a high filler density | concentration may be formed with the foam with the area | region with a low filler density | concentration, and the polymer matrix layer in that case becomes a foam whole. Such a polymer matrix layer in which at least a part in the thickness direction is a foam is a laminate comprising a plurality of layers (for example, a non-foamed layer containing a filler and a foamed layer not containing a filler) as described above. You may be comprised by. The polymer matrix layer composed of the foam will be described later.

  It should be noted that the filler is unevenly distributed in the thickness direction, so that the filler concentration in both outer regions in the thickness direction is lower than that in the inner region in the thickness direction, and the direction of the magnetic poles is the same. The polymer matrix layer in which at least two magnetized polymer matrix layers are laminated uses two magnetized polymer matrix layers in which fillers are unevenly distributed in the thickness direction. It can be manufactured.

  A first step of mixing a magnetic filler with a thermosetting elastomer precursor to prepare a mixed solution, a second step of forming the mixed solution into a sheet, and the magnetic filler being unevenly distributed in the thermosetting elastomer precursor A third step, a fourth step of heating and curing the thermosetting elastomer precursor, a fifth step of magnetizing the magnetic filler to form a polymer matrix layer in which the magnetic filler is unevenly distributed, and the magnetic filler A production method comprising a sixth step of laminating at least two of the unevenly distributed polymer matrix layers. In the sixth step, it is preferable to laminate two magnetized polymer matrix layers so that the directions of the magnetic poles are the same, and in the thickness direction, the other is compared with one region. It is preferable to laminate two polymer matrix layers having a high filler concentration in the region so that the regions having a high filler concentration face each other.

  Furthermore, when laminating the polymer matrix layers in the sixth step, when the self-adhesion is performed by heating at 70 to 130 ° C. for 0.5 to 3 hours, the flexibility of the polymer matrix layer is not impaired, and the sensitivity Is preferable because it is possible to prevent a decrease in the thickness.

  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 styrene-based thermoplastic elastomer, polyolefin-based thermoplastic elastomer, polyurethane-based thermoplastic elastomer, polyester-based thermoplastic elastomer, polyamide-based thermoplastic elastomer, polybutadiene-based thermoplastic elastomer, polyisoprene-based 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. The mixed liquid is poured into a mold subjected to a release treatment, and then heated to a curing temperature and cured to produce a magnetic elastomer. 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, and the reaction of the resulting reaction mixture with organic polyol. 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 material that does not contain bubbles. However, from the viewpoint of improving stability and sensor sensitivity, and further from the viewpoint of weight reduction, the polymer matrix layer 3 is a foamed material containing bubbles as described above. There may be. 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, “Kaorraiser No. 1”, “Kaorraiser 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 are determined by observing the cross section of the polymer matrix layer with a SEM at a magnification of 60 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 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, for example, 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 is 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-mentioned embodiment, the polymer matrix layer has shown an example in which the filler that changes the external field according to the deformation of the polymer matrix layer is dispersed and contained. However, in the present invention, for example, a sheet-like permanent magnet layer or a laminate in which a solid permanent magnet is sandwiched between thermosetting elastomers may be used as the polymer matrix layer.

  In the above-described embodiment, the polymer matrix layer 3 is sandwiched in the gap between the adjacent unit cells 2 (see FIG. 2), and the example is sandwiched in the gap between the unit cell 2 and the housing 11 (see FIG. 2). However, 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.)
Neodymium filler: MF-15P (average particle size: 133 μm, manufactured by Aichi Steel Corporation)
Bismuth octylate: Pucat 25 (Nippon Chemical 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
The reaction vessel was charged with 85.2 parts by weight of polyol A and dehydrated under reduced pressure for 1 hour with stirring. Thereafter, the inside of the reaction vessel was purged with nitrogen. Next, 14.8 parts by weight of TDI-80 was added to the reaction vessel and reacted for 5 hours while maintaining the temperature in the reaction vessel at 80 ° C. to obtain isocyanate-terminated prepolymer A (NCO% = 3.58%). Was synthesized.

  Next, a neodymium-based filler (manufactured by Aichi Steel Co., Ltd., MF-15P) of 675.3 weights in a mixed solution of 189.4 parts by weight of polyol A and 0.35 parts by weight of bismuth octylate (manufactured by Nippon Chemical Industry Co., Ltd., PACCAT 25). Part was added to prepare a filler dispersion. Further, 100.0 parts by weight of prepolymer A was added to the filler dispersion, and mixing and defoaming were performed with a rotation / revolution mixer (manufactured by Sinky). This reaction solution was dropped onto a release-treated PET film having a 0.75 mm spacer and adjusted to a thickness of 0.75 mm with a nip roll. Then, it was allowed to stand at room temperature for a predetermined time (the uneven distribution treatment time described in Table 2) and cured at 80 ° C. for 1 hour to obtain a polyurethane elastomer containing a magnetic filler. The obtained polyurethane elastomer was magnetized at 2.0 T with a magnetizing device (manufactured by Electronic Magnetic Industry Co., Ltd.) to obtain a magnetic polyurethane elastomer. The formulation and production conditions are shown in Table 2.

  By using the obtained two magnetic polyurethane elastomers and laminating so that the magnetic poles have the same direction and both outer sides in the thickness direction are regions having a low magnetic filler concentration, a polymer matrix is obtained. Layers were constructed (Figure 4). In the laminated polymer matrix layer 3 shown in FIG. 4, the upper magnetic polyurethane elastomer 31 has an N pole on the (1) side, a magnetic filler is unevenly distributed on the (1) side, and the S (2) side is S. The magnetic filler is laminated so that the magnetic filler concentration on the (2) side is high. On the other hand, in the lower magnetic polyurethane elastomer 32, the (4) side is the S pole, the magnetic filler is unevenly distributed at a low concentration on the (4) side, the (3) side is the N pole, and (3) The layers are laminated so that the magnetic filler concentration on the side becomes high.

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. In addition, about Example 5, it was set as the structure similar to Example 4 except having used the monolayer body whose thickness of the polyurethane elastomer containing a magnetic filler is 1.5 mm, and not making it the laminated product. Table 2 shows the uneven distribution ratios of the magnetic poles and fillers in the respective regions (1) to (4) of the laminated polymer matrix layer 3.

(Filler uneven distribution rate)
A cross section (thickness: 1.5 mm) of the produced magnetic polyurethane resin was measured using a scanning electron microscope-energy dispersive X-ray analyzer (SEM-EDS) (SEM: S-3500N manufactured by Hitachi High-Technologies Corporation, EDS: Horiba, Ltd.) Using EMAX model 7021-H), observation was performed at 60 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 the Fe element specific to the magnetic filler was determined by elemental analysis for the entire thickness direction of the cross section and four regions obtained by dividing the cross section into four equal parts in the thickness direction. For this abundance, the ratio of each region to the entire region in the thickness direction was calculated.

  A magnetic polyurethane resin having a thickness of 25.0 mm produced by the same method as above was cut into two with a band saw. The cut magnetic polyurethane resin was subjected to a compression test at room temperature at a compression speed of 1 mm / min using Autograph AG-X (manufactured by Shimadzu Corporation) in accordance with JIS K-7312. As the test piece, a right cylindrical sample having a thickness of 12.5 mm and a diameter of 29.0 mm was used. In addition, the compression elastic modulus was calculated | required from the stress value in 2.4%-2.6% strain.

(Evaluation of sensor characteristics)
A hall element (EQ-430L, manufactured by Asahi Kasei Electronics Co., Ltd.) as a detection unit was attached to a stainless steel plate with a double-sided tape. A magnetic polyurethane resin (size: 5 mm × 5 mm) produced from this upper surface was attached, pressure was applied using a surface indenter of 10 mm × 10 mm, and the change in magnetic flux density with respect to the initial value at a predetermined strain amount was measured. The smaller this value, the smaller the change in magnetic flux density with respect to the slight strain. The number of tests was n = 10. The table shows the magnetic flux density change at 5% strain and the characteristic stability calculated based on the following equation.
Stability (%) = (Maximum magnetic flux density change−Minimum magnetic flux density change) / Average magnetic flux density change × 100

  From the results shown in Table 2, in the deformation detection sensor of the sealed secondary battery provided with the polymer matrix layers obtained in Examples 1 to 5, the small deformation of about 5% strain, which is seen when the secondary battery is normal. It can be seen that sometimes the magnetic flux density change is small and the stability is excellent. On the other hand, in the deformation detection sensor for a sealed secondary battery provided with the polymer matrix layer obtained in Comparative Example 1, the change in magnetic flux density is already large and the stability is poor at the time of a small deformation of about 5% strain. Therefore, it can be seen that the object of the present invention of detecting only an abnormal time without malfunction cannot be achieved.

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

Claims (14)

In a deformation detection sensor for a sealed secondary battery,
A polymer matrix layer and a detector;
The polymer matrix layer is to change the external field according to deformation of the polymer matrix layer, and the detection unit detects a change in the external field,
The deformation detection sensor for a sealed secondary battery, wherein the polymer matrix layer has a higher elastic modulus in an inner region in the thickness direction than an elastic modulus in an outer secondary battery side region in the thickness direction.   The deformation detection sensor for a sealed secondary battery according to claim 1, wherein the polymer matrix layer contains a filler that changes an external field according to deformation of the polymer matrix layer.   The deformation detection sensor for a sealed secondary battery according to claim 1, wherein the polymer matrix layer has an elastic modulus in an inner region in the thickness direction higher than an elastic modulus in both outer regions in the thickness direction.   4. The polymer matrix layer according to claim 1, wherein the elastic modulus of the inner region in the thickness direction is higher by 1 MPa or more than the elastic modulus of the outer secondary battery side region in the thickness direction. The deformation | transformation detection sensor of the sealed secondary battery as described. The polymer matrix layer contains a magnetic filler as the filler,
The deformation detection sensor for a sealed secondary battery according to any one of claims 1 to 4, wherein the detection unit detects a change in a magnetic field as the external field.   The polymer matrix layer is one in which the filler is unevenly distributed in the thickness direction, and the filler concentration in both outer regions in the thickness direction is lower than that in the inner region in the thickness direction. 5. A deformation detection sensor for a sealed secondary battery according to any one of 5 above.   The deformation detection sensor for a sealed secondary battery according to claim 1, wherein the polymer matrix layer is a laminated structure having at least two polymer matrix layers.   8. The detection of deformation of a sealed secondary battery according to claim 7, wherein at least two of the polymer matrix layers are both magnetized and laminated so that the directions of the magnetic poles are the same. Sensor.   A sealed secondary battery to which the deformation detection sensor according to any one of claims 1 to 8 is attached. A first step of mixing a magnetic filler with a thermosetting elastomer precursor to prepare a mixed solution, a second step of forming the mixed solution into a sheet, and the magnetic filler being unevenly distributed in the thermosetting elastomer precursor A third step, a fourth step of heating and curing the thermosetting elastomer precursor, a fifth step of magnetizing the magnetic filler to form a polymer matrix layer in which the magnetic filler is unevenly distributed, and the magnetic filler the uneven distribution and said polymer matrix layer seen including a sixth step of laminating at least two sheets,
In the sixth step, two magnetized polymer matrix layers are laminated so that the magnetic poles have the same direction, and the two polymer matrix layers are formed in a region where the concentration of the magnetic filler is high. A method of manufacturing a deformation detection sensor for a sealed secondary battery , wherein the layers are stacked so that they face each other .   11. The deformation detection of the sealed secondary battery according to claim 10, wherein when the polymer matrix layers are laminated in the sixth step, the polymer matrix layers are self-adhered by heating at 70 to 130 ° C. for 0.5 to 3 hours. Sensor manufacturing method. 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 changes the external field in accordance with deformation of the polymer matrix layer, and has an inner thickness in the thickness direction as compared to the elastic modulus of the outer secondary battery side region in the thickness direction. The elastic modulus of the region is high,
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.   The method for detecting deformation of a sealed secondary battery according to claim 12, wherein the polymer matrix layer contains a filler that changes an external field according to deformation of the polymer matrix layer. The polymer matrix layer contains a magnetic filler as the filler,
The method for detecting deformation of a sealed secondary battery according to claim 12 or 13, wherein the detecting unit detects a change in a magnetic field as the external field.

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