JP2019002694A - Monitoring sensor and sealed secondary battery - Google Patents

Abstract

To provide a monitoring sensor with improved detection stability.SOLUTION: A monitoring sensor 5 comprises: a polymer matrix layer 3 which is sandwiched between a first member (a casing 11) and a second member (an exterior body 21) and which is deformed depending on a state change of a monitoring object; a spacer 6 which, together with the polymer matrix layer 3, is sandwiched between the first member (the casing 11) and the second member (the exterior body 21); and a detector 4 which detects a change of an external field occurring depending on the deformation of the polymer matrix layer 3. The spacer 6 is a spring 6 stretching in a thickness direction AD of the polymer matrix layer 3.SELECTED DRAWING: Figure 1C

Description

  The present disclosure relates to a monitoring sensor that detects a change in the state of a monitoring object and a sealed secondary battery provided with the monitoring sensor.

  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 that expansion detection means including a rubber spacer and a displacement detection sensor is provided in a gap between a battery and an exterior body to detect deformation of the battery as a monitoring object. However, since rubber is used as the spacer, hysteresis loss occurs in the rubber due to repeated deformation of the rubber, and the stability of the sensor deteriorates.

  In Patent Document 2, a polymer matrix layer containing a magnetic filler disposed between adjacent batteries or between a battery and a casing, and changes in the external field due to deformation of the polymer matrix layer are detected. A deformation detection sensor including a detection unit is disclosed. However, in this configuration, since there is no spacer, it depends on the physical properties of the polymer matrix layer, and hysteresis loss occurs in the polymer matrix layer due to repeated deformation of the polymer matrix layer, and the stability of the sensor deteriorates.

International Publication No. 2012/073770 JP 2006-100260 A

  The present disclosure has been made paying attention to such circumstances, and an object thereof is to provide a monitoring sensor with improved detection stability and a sealed secondary battery having the monitoring sensor attached thereto. It is.

  In order to achieve the above object, the present disclosure takes the following measures.

  The monitoring sensor of the present disclosure is sandwiched between the first member and the second member, and is deformed in accordance with the state change of the monitoring object, and the first member and the second member together with the polymer matrix layer. The spacer includes a sandwiched spacer and a detection unit that detects a change in an external field that occurs according to deformation of the polymer matrix layer, and the spacer is a spring that expands and contracts in the thickness direction of the polymer matrix layer.

  According to this configuration, when the polymer matrix layer is deformed in accordance with the state change (deformation, displacement, load change, pressure change) of the monitored object, the spring as a spacer between the first member and the second member However, it expands and contracts with the polymer matrix layer in the thickness direction of the polymer matrix layer. The spring has higher rigidity and higher elasticity than the polymer matrix layer. Therefore, the deformation of the polymer matrix layer follows the load-deflection characteristic of the spring, and hysteresis loss and creep are reduced, so that detection stability can be improved.

The perspective view which shows typically the monitoring sensor provided in the sealed secondary battery of 1st Embodiment of this indication. AA sectional drawing in FIG. 1A. 1A is a cross-sectional perspective view taken along line AA in FIG. Sectional drawing which shows the modification in an AA site | part. 1 is a perspective view showing Example 1. FIG. Sectional drawing which shows typically the modification of the monitoring sensor provided in the sealed secondary battery.

  Hereinafter, embodiments of the present disclosure will be described.

<First Embodiment>
A monitoring sensor 5 that detects a change in the state of the secondary battery 2 that is a monitoring target is attached to the sealed secondary battery 2 shown in FIGS. 1A, 1B, and 1C. The state change detected by the monitoring sensor 5 includes at least one of deformation, displacement, load change, and pressure change.

  The monitoring sensor 5 includes a polymer matrix layer 3, a detection unit 4, and a spacer 6. The single battery constituting the secondary battery 2 has a structure in which an electrode group 22 is accommodated inside a sealed outer package 21. The electrode group 22 of the present embodiment is formed by laminating a positive electrode 23 and a negative electrode 24 with a separator 25 interposed therebetween, and the laminate is included in the outer package 21 together with the electrolytic solution. Leads are connected to the positive electrode 23 and the negative electrode 24, respectively, and their end portions project outside the exterior body 21 to constitute electrode terminals.

  The secondary battery 2 of the present embodiment is a laminated battery using a laminated film such as an aluminum laminated foil as the outer package 21, and is specifically a laminated lithium ion secondary battery having a capacity of 1.44 Ah. The exterior body 21 has a plurality of wall portions and welded portions 29 formed on the three surrounding sides, and is formed in a thin rectangular parallelepiped shape as a whole. The X, Y, and Z directions correspond to the length direction, the width direction, and the thickness direction of the secondary battery 2, respectively.

  In FIG. 1A, FIG. 1B, and FIG. 1C, only one secondary battery 2 as a single battery is shown, but in a secondary battery 2 for an application that requires a high voltage, such as a power source for an electric vehicle, It is used in the form of a battery module including a plurality of single cells. In the battery module, a plurality of single cells constitute an assembled battery and are accommodated in the housing 11. Generally, a battery module mounted on a vehicle is used in the form of a battery pack. In a battery pack, a plurality of battery modules are connected in series, and they are housed in a casing together with various devices such as a controller. The casing 11 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. The secondary battery 2 is accommodated in the housing 11.

  The polymer matrix layer 3 is installed so as to be deformed in accordance with a change in the state of the monitored object. In the present embodiment, the secondary battery 2 is an object to be monitored, and the polymer matrix layer 3 is attached to the exterior body 21 of the secondary battery 2. The polymer matrix layer 3 contains a dispersed magnetic filler that changes the external field according to the deformation of the polymer matrix layer 3. And the detection part 4 detects the change of the external field accompanying the deformation | transformation of the polymer matrix layer 3. FIG. The polymer matrix layer 3 of the present embodiment is formed in a sheet shape from an elastomer material that can be flexibly deformed according to the swelling of the secondary battery 2. When the outer casing 21 is deformed by the swelling of the secondary battery 2, the polymer matrix layer 3 is deformed accordingly, and the change in the external field due to the deformation of the polymer matrix layer 3 is detected by the detection unit 4, Based on this, deformation of the secondary battery 2 can be detected with high sensitivity.

  In the present embodiment, the polymer matrix layer 3 is sandwiched between the first member (housing 11) and the second member (the outer package 21 of the secondary battery 2). The spacer 6 is sandwiched between the first member (housing 11) and the second member (exterior body 21) together with the polymer matrix layer 3. Since the detection unit 4 is fixed to the outer surface of the first member (housing 11), the positional relationship with the polymer matrix layer 3 and the second member (exterior body 21) is maintained. In the present embodiment, the distance between the first member (housing 11) and the second member (exterior body 21) is larger than the thickness of the polymer matrix layer 3 and the spacer 6 in a natural state where no external force is applied. Thus, the polymer matrix layer 3 and the spacer 6 are sandwiched between the exterior body 21 and the casing 11 in a compressed state, but the present invention is not limited to this. For example, the gap between the first member and the second member and the thicknesses of the polymer matrix layer 3 and the spacer 6 may be the same size, and the polymer matrix layer 3 and the spacer 6 may not be compressed.

  The spacer 6 is a spring 6 that expands and contracts in the thickness direction AD of the polymer matrix layer 3. The spring 6 is more rigid and elastic than the polymer matrix layer 3. In the present embodiment, the spring 6 is a metal disc spring, but is not limited thereto. For example, a coil spring, a conical spring, a leaf spring, a torsion spring, or a mainspring spring can be used. The material of the spring 6 is not limited to metal as long as it has higher rigidity and higher elasticity than the polymer matrix layer 3. For example, ceramic or resin may be used. In the present embodiment, the spring 6 is a single disc spring having a hollow portion at the center, and the polymer matrix layer 3 is disposed in the hollow portion. According to this configuration, forces from all directions around the polymer matrix layer 3 can be supported and received, which is preferable from the viewpoint of stability. Of course, the present invention is not limited to this. For example, a plurality of disc springs may be arranged around the polymer matrix layer 3. It is also conceivable to arrange a plurality of other types of springs such as leaf springs as well as disc springs.

  Among various springs, a spring having a flat shape in which the height dimension H1 corresponding to the thickness direction AD of the polymer matrix layer 3 is smaller than the width dimension W1 orthogonal to the height is preferable. Specific examples include a disc spring and a leaf spring. This is because the dimension in the thickness direction can be suppressed. A linear spring having a linear load and deflection characteristic is preferable, but a non-linear spring may be used.

  In addition, when the polymer matrix layer 3 is compressed exceeding 50% of the thickness of the polymer matrix layer 3 in a natural state where no external force is applied, the elastic modulus of the magnetic elastomer becomes too high, and thus the sensitivity is increased. Getting worse. Therefore, the allowable deformation amount of the spring 6 is preferably 50% or less of the thickness of the polymer matrix layer 3 in a natural state where no external force is applied. According to this configuration, the deformation of the matrix layer due to the expansion and contraction of the spring is suppressed to 50% or less, and it is possible to prevent the sensitivity due to the matrix layer from being obtained and to ensure stability.

  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.

  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 a polyol and a polyisocyanate. 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 here 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 diisocyanate, more preferably 2,4-toluene diisocyanate, 2,6-toluene diisocyanate.

  As the active hydrogen-containing compound, those usually used in the technical field of polyurethane can be used. 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 such as polyester polyol, polycaprolactone polyol, reaction product of polyester glycol such as polycaprolactone glycol and alkylene carbonate, and ethylene carbonate are reacted with polyhydric alcohol. Polyester polycarbonate polyol reacted with organic dicarboxylic acid, polyhydroxyl compound and aryl carbonate It can be mentioned a high molecular weight polyol and polycarbonate polyols obtained by ester exchange reaction. 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.

  Preferred combinations of the isocyanate component and the active hydrogen-containing compound include, as the isocyanate component, one or more of 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, and 4,4′-diphenylmethane diisocyanate, and active hydrogen. The containing compound is polytetramethylene glycol, polypropylene glycol, a copolymer of propylene oxide and ethylene oxide, and a combination of one or more of 3-methyl-1,5-pentaneadipate. More preferably, it is a combination of 2,4-toluene diisocyanate and / or 2,6-toluene diisocyanate as the isocyanate component and polypropylene glycol and / or a copolymer of propylene oxide and ethylene oxide as the active hydrogen-containing compound. is there.

  The polymer matrix layer 3 may be a foam containing dispersed fillers and bubbles. A general resin foam can be used as 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.

  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 the purpose of preventing rust of the magnetic filler, a sealing material for sealing the polymer matrix layer 3 may be provided to the extent that the flexibility of the polymer matrix layer 3 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 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, 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. These films may be laminated, or may be a film including a metal foil such as an aluminum foil or a metal vapor deposition film in which a metal is vapor deposited on the film.

  The polymer matrix layer 3 may be one in which fillers are unevenly distributed in the thickness direction. For example, the polymer matrix layer 3 may have a structure composed of two layers of a region on one side with a relatively large amount of filler and a region on the other side with a relatively small amount of filler. In the region on one side containing a large amount of filler, the change in the external field with respect to small deformation of the polymer matrix layer 3 becomes large, so that the sensor sensitivity to a low internal pressure can be enhanced. Further, the region on the other side with relatively little filler is relatively flexible and easy to move. By attaching this region, the polymer matrix layer 3 (especially the region on one side) is likely to be deformed.

  The filler uneven distribution ratio in the region on one side is preferably more than 50, more preferably 60 or more, and still more preferably 70 or more. In this case, the filler uneven distribution rate in the other region is less than 50. The filler uneven distribution rate in the region on one side is 100 at the maximum, and the filler uneven distribution rate in the region on the other side is 0 at the minimum. Therefore, a laminate structure of an elastomer layer containing a filler and an elastomer layer not containing a filler may be used. 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. Alternatively, the polymer matrix layer may be constituted by a laminate composed of a plurality of layers having different filler contents.

  The filler uneven distribution rate is measured by the following method. That is, the cross section of the polymer matrix layer is observed at 100 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 two areas obtained by dividing the cross section into two in the thickness direction are each subjected to elemental analysis of a metal element specific to the filler (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 other side region with relatively little filler may have a structure formed of a foam containing bubbles. Thereby, the polymer matrix layer 3 is further easily deformed and the sensor sensitivity is enhanced. Moreover, the area | region of one side may be formed with the foam with the area | region of the other side, and the polymer matrix layer 3 in that case becomes a foam entirely. Such a polymer matrix layer in which at least a part in the thickness direction is a foam is composed of a laminate composed of a plurality of layers (for example, a non-foamed layer containing a filler and a foamed layer not containing a filler). It doesn't matter.

  For example, a reed switch, a magnetoresistive element, a Hall element, a coil, 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 has high sensitivity over a wide range and is useful as the detection unit 4. As the Hall element, for example, EQ-430L, EQ-431L, EQ-432L manufactured by Asahi Kasei Electronics Corporation can be used.

  In order to specifically show the effect of the monitoring sensor of the present disclosure, the following evaluation was performed on the following examples.

Example 1
As shown in FIG. 2, a magnetic silicone resin (φ5 × 0.7 mm) as the polymer matrix layer 3 and a disc spring (outer diameter φ10, inner diameter φ6, free height 0.7 mm) as the spring 6 are 1 A 44 Ah unit cell (90 × 30 × 4 mm) was attached. These members and the battery 2 were sandwiched between two aluminum plates 7A and 7B (110 × 90 × 2 mm). On the upper aluminum plate 7A, a magnetic sensor (EQ-430L, manufactured by Asahi Kasei Electronics Co., Ltd.) serving as the detection unit 4 was installed so as to be positioned above the center of the polymer matrix layer 3 (magnetic silicone resin). A load was applied to the aluminum plates 7A and 7B until the detector 4 (magnetic sensor) was compressed to about 15% of the free height of the disc spring in a universal testing machine while avoiding a direct load from being applied. Thereafter, the upper and lower aluminum plates 7A and 7B were brought into a state in which the load was held by bolting (the polymer matrix layer 3 and the spring 6 were compressed) and removed from the universal testing machine.

  In Example 1, the thickness (height) of the uncompressed spring and the magnetic silicone resin is the same, but not necessarily limited thereto. For example, it is possible to adjust the sensor characteristics by making the thickness (height) of the magnetic silicone resin higher than the free height of the spring to make it more compressed.

Comparative Example 1
Resin spacers were used instead of the springs 6. Magnetic silicone resin (φ5 × 0.7 mm) as the polymer matrix layer 3 and silicone resin (SE1740 manufactured by Toray Dow Co., Ltd.) as the resin spacer (φ8 × 0.7 mm punched hole at the center of φ16 × 0.7 mm) Was attached to a 1.44 Ah cell (90 × 30 × 4 mm). As in Example 1, a load was applied to the aluminum plate until the silicone spacer was compressed by about 15% of its thickness. The amount of compression was adjusted so that the following sensor sensitivity was almost the same as in Example 1.

Comparative Example 2
Without providing a spacer, only a magnetic silicone resin (φ5 × 0.7 mm) as the polymer matrix layer 3 was attached to a single cell (90 × 30 × 4 mm) of 1.44 Ah. As in Example 1, a load was applied to the aluminum plate until the silicone spacer was compressed by about 15% of its thickness.

(1) Sensor sensitivity The aluminum plate containing the battery is kept in a load with a bolt (maintained in a compressed state), placed in a constant temperature bath at 25 ° C., and allowed to stand for 120 minutes. A constant current charge to 4.3V was performed at a charging current of 1.5V, and after reaching 4.3V, a constant voltage charge was performed until the current value decreased to 0.07A. Then, after maintaining the open circuit state for 10 minutes, constant current discharge was performed to 3.0V with the electric current of 1.44A. The charge / discharge process was repeated 5 cycles, and the change in magnetic flux density during charge / discharge was measured. The change in magnetic flux density at the first cycle was defined as sensor sensitivity. The larger the amount of change, the better the sensitivity performance as a sensor.

(2) Stability The rate of change was calculated by comparing the magnetic flux density at the start of charging in the first cycle with the magnetic flux density at full discharge in the fifth cycle. As the change rate is smaller, the polymer matrix layer 3 and the spacer are not creep-deformed, the hysteresis loss is reduced, and the sensor stability is excellent.

Comparative Example 1 has a configuration in which a silicone spacer is provided instead of a disc spring. The comparative example 2 is a structure which does not provide spacers, such as a disk spring and a silicone spacer. In Comparative Example 1, by repeating the charge / discharge cycle, the magnetic flux density was deteriorated by about 4.4% compared to Example 1 from the initial stage. It is considered that this is because permanent deformation occurred in the silicone spacer by the repeated test, and the thickness of the polymer matrix layer changed before and after the charge / discharge.
In Comparative Example 2, the magnetic flux density deteriorated by approximately 8.9% from the initial stage by repeating the charge / discharge cycle as compared with Example 1. This is considered to be caused by permanent deformation in the polymer matrix layer due to the repeated test, and the thickness of the polymer matrix layer changing before and after the charge / discharge.
On the other hand, when the disc spring of Example 1 is provided, if the amount of elastic deformation is within the range where plastic deformation does not occur (within the allowable deformation amount of the spring), the same amount of displacement can be obtained even after repeated charge / discharge cycles. It can be obtained that the stability is improved.

  As described above, the monitoring sensor 5 of the present embodiment is sandwiched between the first member (housing 11) and the second member (exterior body 21), and the polymer matrix layer 3 is deformed according to the state change of the monitoring object. A spacer 6 sandwiched between the first member (housing 11) and the second member (exterior body 21) together with the polymer matrix layer 3, and a detection unit that detects changes in the external field caused by deformation of the polymer matrix layer 3 The spacer 6 is a spring 6 that expands and contracts in the thickness direction AD of the polymer matrix layer 3.

  According to this configuration, when the polymer matrix layer 3 is deformed according to the state change (deformation, displacement, load change, pressure change) of the monitoring object, the first member (housing 11) and the second member ( The spring 6 as a spacer between the exterior bodies 21) expands and contracts together with the polymer matrix layer 3 in the thickness direction AD of the polymer matrix layer 3. The spring 6 has higher rigidity and higher elasticity than the polymer matrix layer 3. Therefore, the deformation of the polymer matrix layer 3 follows the load-deflection characteristic of the spring, and hysteresis loss and creep are reduced, so that detection stability can be improved.

  In the present embodiment, the spring 6 has a flat shape in which the height dimension H1 corresponding to the thickness direction AD of the polymer matrix layer 3 is smaller than the width dimension W1.

  According to this configuration, for example, the dimension in the thickness direction AD can be suppressed as compared with a coil spring having the thickness direction AD of the polymer matrix layer 3 as an axial direction.

  In this embodiment, the spring 6 is a disc spring. Since the disc spring has a flat shape with a small height relative to the lateral width, it is suitable for thinning.

  In the present embodiment, the allowable deformation amount of the spring 6 is 50% or less of the thickness of the polymer matrix layer 3 in a natural state where no external force is applied.

  According to this configuration, the deformation of the polymer matrix layer 3 due to the expansion and contraction of the spring 6 is suppressed to 50% or less, and it is possible to prevent stability from being obtained by the polymer matrix layer 3 and to ensure stability.

  In the present embodiment, the second member is a member (exterior body 21) constituting the secondary battery 2 that is the monitoring target.

  According to this configuration, when the state change (deformation, displacement, load change, pressure change) occurs in the monitoring object, the polymer matrix layer 3 is deformed, so that the state change can be detected through the detection unit 4. it can. Of course, the present invention is not limited to this configuration, and at least one of the first member and the second member is in contact with a member constituting the monitoring object, or at least one of the first member and the second member is the monitoring target. What is necessary is just the member which comprises a thing.

  In this embodiment, the polymer matrix layer 3 contains a magnetic filler, and the detection unit 4 detects a change in the magnetic field. In this case, the first member and the second member are preferably nonmagnetic materials.

  In the present embodiment, the monitoring sensor 5 is attached, and the monitoring object is set as a member (exterior body 21) constituting the secondary battery 2. According to this configuration, the state change of the secondary battery 2 can be detected appropriately.

  The structure employed in each of the above embodiments can be employed in any other embodiment. The specific configuration of each unit is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present disclosure.

<Other embodiments>
In the first embodiment, the polymer matrix layer 3 and the spacer 6 are sandwiched between the casing 11 as the first member and the battery 2 as the second member. However, the present invention is not limited to this. For example, as shown in FIG. 1D, another member 7 may be provided between the polymer matrix layer 3 and the battery 2. In this case, the first member is the casing 11 and the second member is the member 7. The member 7 that is the second member is in contact with the member (the outer package 21) that constitutes the secondary battery 2 that is the monitoring target. That is, it is only necessary that at least one of the first member and the second part 2 member is in contact with a member constituting the monitoring target.

  As shown in FIG. 3, the battery module 1 includes a housing 11 and a plurality of single cells 2 housed inside the housing 11. The polymer matrix layer 3 and the spacer 6 are sandwiched between the first battery 2 and the second battery 2. In this case, since both the first battery 2 and the second battery can be deformed, it can be said that they are both the first member and the second member. Of course, it is not limited to the example of the first embodiment, FIG. 3 and FIG. 1D, and any member may be used as long as it is a monitoring object among the members constituting the battery module 1. You may arrange | position inside a battery. That is, at least one of the first member and the second member may be a member that constitutes the monitoring target.

  In the above-described embodiment, an example in which the secondary battery cell is a lithium ion secondary battery has been described, but the present invention is not limited thereto. The secondary battery cell used 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-hydrogen battery.

  In the above-described embodiment, the example in which the change in the magnetic field due to the deformation of the polymer matrix layer is detected by the detection unit has been described. However, another change in the external field may be detected. 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.

11 ... Case (first member)
21 ... Exterior body (second member)
3 ... polymer matrix layer 6 ... spring (spacer)

Claims (7)

A polymer matrix layer that is sandwiched between the first member and the second member and deforms in accordance with the state change of the monitoring object;
A spacer sandwiched between the first member and the second member together with the polymer matrix layer;
A detection unit that detects a change in the external field that occurs in response to deformation of the polymer matrix layer,
The monitoring sensor, wherein the spacer is a spring that expands and contracts in the thickness direction of the polymer matrix layer.   The sensor according to claim 1, wherein the spring has a flat shape in which a height dimension corresponding to a thickness direction of the polymer matrix layer is smaller than a width dimension.   The sensor according to claim 1, wherein the spring is a disc spring.   The sensor according to any one of claims 1 to 3, wherein an allowable deformation amount of the spring is 50% or less of a thickness of the polymer matrix layer in a natural state where no external force is applied. At least one of the first member and the second member is in contact with a member constituting the monitoring object,
Or
The sensor according to any one of claims 1 to 4, wherein at least one of the first member and the second member is a member constituting the monitoring object.   The sensor according to claim 1, wherein the polymer matrix layer contains a magnetic filler, and the detection unit detects a change in a magnetic field.   A sealed secondary battery, to which the sensor according to any one of claims 1 to 6 is attached, and the monitoring object is set to a member constituting the sealed secondary battery.

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