JP2014238915A - Laminated battery and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated battery which can be manufactured easily while reducing the manufacturing cost, and in which occurrence of short circuit or sudden short circuit can be prevented effectively.SOLUTION: A laminated battery includes a laminated electrode body produced by laminating a positive electrode plate 1 where a positive electrode active material layer 1a is formed on a positive electrode collector, and a negative electrode plate where a negative electrode active material layer is formed on a negative electrode collector, with a separator 3a interposed therebetween, and the positive electrode plate 1 and negative electrode plate have a positive electrode lead 11 and a negative electrode lead projecting from the peripheral part, respectively. In at least one of the positive electrode lead 11 and negative electrode lead, a protective layer 13A composed of a photo-curing resin is formed at a part adjacent to the positive electrode active material layer 1a or the negative electrode active material layer.

Description

  The present invention relates to a stacked battery and a method for manufacturing the same, and more particularly to a stacked battery using a stacked electrode body in which square positive and negative plates and a separator are stacked, and a method for manufacturing the same.

  In recent years, batteries have been used not only for power sources of mobile information terminals such as mobile phones, notebook personal computers, and PDAs, but also for robots, electric vehicles, backup power sources, etc., and further increase in capacity is required. It has become like this. In response to such demands, particularly in the field of secondary batteries, non-aqueous secondary batteries represented by lithium ion batteries having high energy density and high capacity are widely used as drive power sources as described above. Yes.

  Battery types of such lithium ion batteries can be broadly divided into a spiral type in which a spiral electrode body is enclosed in an exterior body, and a laminated electrode body in which a plurality of rectangular electrodes are laminated, and an exterior can or laminate film is welded. And a laminated type (laminated type prismatic lithium ion battery) encapsulated in a laminated outer package produced by doing so.

  Among these lithium ion batteries, the specific structure of the laminated electrode body of the laminated battery is a sheet-like positive electrode plate with a positive electrode lead extended and a sheet-like negative electrode plate with a negative electrode lead extended, A required number of layers are laminated through a separator made of polyethylene, polypropylene, or the like.

  In the laminated battery, two separators are joined at the peripheral edge to form a bag shape, and either one of the positive electrode plate and the negative electrode plate is accommodated in the bag-like separator. Alternatively, a laminated electrode body is conventionally formed by alternately laminating a bag-shaped separator in which a negative electrode plate is accommodated and a negative electrode plate or a positive electrode plate not accommodated in the bag-shaped separator. According to this configuration, since either one of the positive electrode plate and the negative electrode plate is held in the state of being accommodated in the bag-like separator, the positive electrode plate and the negative electrode plate are brought into contact with each other due to misalignment or the like, and are short-circuited. Can be prevented.

  By the way, in a non-aqueous secondary battery typified by a lithium ion battery, a negative electrode mixture coating portion of a negative electrode plate is used to reliably and smoothly occlude lithium ions released from the positive electrode active material during charging into the negative electrode active material. Is preferably formed to have a larger area than the positive electrode mixture coating portion of the positive electrode plate. For this reason, at the edge portion of the positive electrode plate, the positive electrode lead portion is formed by extending a metal sheet such as an aluminum foil as a current collector without applying the positive electrode mixture, In general, the exposed portion of the metal sheet has a structure facing the negative electrode mixture application portion of the negative electrode plate via a separator.

  As described above, when the exposed portion of the metal current collector of one electrode is opposed to the other electrode via the separator, the metal current collector of one electrode is caused by any cause such as an impact caused by dropping or vibration. If the exposed part of the electrode or the other electrode passes through the separator and contacts with each other to cause a short circuit, there is a risk that a large current flows and a violent reaction occurs, resulting in smoke, ignition, or the like. In particular, even when the above-described bag-shaped separator is used, the positive electrode lead is extended at the positive electrode lead portion and the separator cannot be welded, so the separator is likely to be displaced, possibly causing a short circuit. Greater than. Furthermore, in applications that require a large current, this tendency is remarkable because a wide lead portion is formed.

  Further, in the manufacturing process of the electrode body, when the negative electrode plate and the positive electrode plate are cut out, burrs may be generated at the cut ends, and the separator breaks through the burrs, and the negative electrode plate and the positive electrode plate are interposed through the burrs. May be short-circuited.

  Also, in a stacked battery, current is collected by joining a plurality of positive leads extending from the laminated electrode body to a positive current collector terminal in a bundled state. A gap is formed, and the base end portion (root portion) of the positive electrode lead and the separator that is not welded are displaced or twisted, so that a short circuit is likely to occur. In addition, in the case of a stacked battery, the number of stacked electrode plates is inevitably increased to increase the capacity of the battery, and the number of stacked positive electrode leads is also increased. The greater the number, the easier the separator will sag.

  Therefore, as disclosed in Patent Document 1, it has been proposed to form a short-circuit prevention layer made of an insulator at the base portion of the protruding portion that becomes the lead portion of the electrode plate. Thereby, it is possible to prevent the occurrence of a short circuit in the lead portion.

Japanese Patent No. 4366783

  However, in order to form the short-circuit prevention layer as described above, a step of applying a resin to the base portion of the lead portion and a step of drying the applied resin are necessary, which increases the manufacturing cost. .

  In view of the above problems, the present invention provides a stacked battery that can effectively prevent a short circuit or a sudden short circuit and can be easily manufactured to reduce manufacturing costs. The purpose is to provide.

  Another object of the present invention is to provide a method of manufacturing a stacked battery that can easily and inexpensively produce a battery that can effectively prevent the occurrence of a short circuit or a sudden short circuit. .

In order to achieve the above object, the laminated battery according to the present invention is:
Provided is a laminated electrode body in which a positive electrode plate having a positive electrode active material layer formed on a positive electrode current collector and a negative electrode plate having a negative electrode active material layer formed on a negative electrode current collector are laminated via a separator. The positive electrode plate and the negative electrode plate are each a stacked battery having a positive electrode lead and a negative electrode lead protruding from the edge portion, respectively.
In at least one of the positive electrode lead and the negative electrode lead, a protective layer made of a photocurable resin is formed in a portion adjacent to the positive electrode active material layer or the negative electrode active material layer.

  According to the configuration of the present invention, the protective layer can effectively prevent the occurrence of a short circuit or a sudden short circuit in the positive electrode lead or the negative electrode lead. Furthermore, at this time, since the protective layer is made of a photocurable resin, the resin can be cured in a short time by irradiation with light. Accordingly, the protective layer can be easily formed and the manufacturing cost can be reduced as compared with the case where a long drying process is performed.

  It is desirable that the protective layer is formed on the positive electrode lead.

  The protective layer may be formed on either the positive electrode lead or the negative electrode lead, or may be formed on both the positive electrode lead and the negative electrode lead. However, as described above, the negative electrode mixture application portion of the negative electrode plate, that is, the negative electrode active material layer is preferably formed to have a larger area than the positive electrode mixture application portion of the positive electrode plate, that is, the positive electrode active material layer. In the positive electrode lead that extends in a state where the metal of the current collector is exposed at the edge portion of the plate, the exposed portion of the metal has a structure facing the negative electrode active material layer through the separator. It is customary. For this reason, although there is a possibility that a short circuit may occur if a large misalignment occurs even in the negative electrode lead, the risk of a short circuit is usually greater in the positive electrode lead. Therefore, it is desirable to form a protective layer at least on the positive electrode lead.

  The positive electrode lead and the negative electrode lead are preferably formed integrally with the positive electrode current collector and the negative electrode current collector, respectively.

  For example, a positive electrode lead or a negative electrode lead prepared separately may be joined to the positive electrode current collector or the negative electrode current collector by welding or the like. According to this, however, connection resistance occurs or the thickness of the joint portion is increased. In addition, there is a problem that the ridge corners of the joint portion are liable to cause damage to the separator and cause a short circuit. Therefore, from this point of view, the positive electrode lead or the negative electrode lead can be formed integrally with the positive electrode current collector or the negative electrode current collector, for example, by forming the corner of one metal plate so as to be cut out. desirable.

It is desirable that the separator is formed into a bag shape, and one electrode is accommodated in the bag-shaped separator.

  Although it does not specifically limit as a form of a separator, When it is set as a bag shape by joining a peripheral part by welding etc. in the state where a separator was piled up and this was stored in one electrode, Contact with the other electrode can be effectively prevented. Moreover, since positioning and fixing can be performed in a state where one electrode is housed and held in the bag-shaped separator, positioning and fixing are also facilitated. However, even in the case of this bag-shaped separator, the electrode lead is extended in the electrode lead, so that the separator cannot be joined. Accordingly, the separator is liable to be displaced or twisted. Therefore, by forming a protective layer on the electrode lead, it is possible to effectively prevent a short circuit even if a separator is displaced or twisted in the electrode lead. In other words, although the bag-shaped separator has an effective configuration for preventing a short circuit, there has conventionally been a problem that it is difficult to prevent a short circuit from occurring due to the displacement or twisting of the separator in the electrode lead. In particular, the effect of the present invention in which the protective layer is formed is exhibited.

  It is desirable that a positive electrode plate is accommodated in the bag-shaped separator.

  As described above, since the negative electrode active material layer is preferably formed to have a larger area than the positive electrode active material layer, the negative electrode plate is usually prepared to have a size larger than that of the positive electrode plate. For this reason, it is desirable from the viewpoint of space saving that the positive electrode plate is accommodated in the bag-shaped separator.

  It is desirable that the bag-shaped separator is constructed by intermittently joining the peripheral edges in a state where the separators are overlapped.

  When the peripheral portions are joined intermittently with the separators overlapped, that is, with the unjoined portions remaining, the electrolyte solution can easily penetrate into the electrodes in the bag-like separator through the unjoined portions. it can. In this case, it is desirable that the ratio of the length of the region joined at the peripheral portion (the proportion of the joint region) to the length of the peripheral portion of the separator is about 30 to 70%. By setting the proportion of the joining region to 30 to 70%, the joining strength of the separator is sufficiently strong and the electrolyte permeability is excellent.

  It is desirable that the protective layer has a lower electronic conductivity than the positive electrode lead or the negative electrode lead on which the protective layer is formed, and is non-insulating.

  As a protective layer, in order to prevent generation | occurrence | production of a short circuit, it may not have electronic conductivity, ie, it may have insulation. However, as described above, for example, when the electrode plate is cut out, burrs are generated at the cut end, and even if the burrs break through the separator, if the protective layer is insulative, a short circuit is caused by the protective layer. Charging / discharging is possible as long as it is stopped. Moreover, even if the burr breaks through the separator and comes into contact with the protective layer in this way, it does not appear as a change in voltage, so the occurrence of this abnormality is not detected from the outside. Therefore, if the battery is continuously used in this state for a long time, the damaged portion may be a starting point, and the separator may be broken to cause a sudden short circuit, which may cause the battery to generate abnormal heat. That is, even if it is possible to stop the occurrence of a short circuit once by the insulating protective layer, if the separator further breaks down from that state, a sudden short circuit will occur again, leading to abnormal heat generation. There is a fear.

  Therefore, although the electron conductivity is lower than that of the positive electrode lead or the negative electrode lead on which the protective layer is formed, it is non-insulating (this property is also referred to as “semiconductive” in the present specification, and this semiconductive layer. If the protective layer is formed using a material of a semi-conductive layer, the insulating property is maintained by the protective layer when burrs or the like break through the separator as described above. Rather, it can cause a gentle discharge. Thereby, it is possible to detect an abnormality of the battery on the device side by a decrease in the battery voltage while avoiding abnormal heat generation. In addition, since the battery is gradually discharged and eventually the battery is completely discharged, a large current flows even when a direct short circuit occurs between the positive electrode plate and the negative electrode plate later. There is nothing. Therefore, the safety of the battery can be effectively ensured (see Japanese Patent Application Laid-Open No. 2007-95656).

  It is desirable that the protective layer contains at least one of an epoxy acrylate resin, a urethane acrylate resin, an alicyclic epoxy resin, and a polyester vinyl ether resin.

  The photocurable resin constituting the protective layer of the present invention includes a wide range of resins that can be cured by light. Among them, an ultraviolet curable resin is most preferable from the viewpoint of the curing speed and the like. Since the ultraviolet curable resin is instantly cured when irradiated with ultraviolet rays, a drying step can be eliminated. Further, a solvent to be applied (for example, N-methyl-2-pyrrolidone (NMP)) does not flow into the positive electrode active material layer or the negative electrode active material layer. In general, the ultraviolet curable resin includes a radical polymerization type whose main component is an acrylate, a modified acrylate or an unsaturated polyester, and a cationic polymerization type whose main component is an epoxy resin or vinyl ether. Among the former radical polymerization types, epoxy acrylate resins and urethane acrylate resins are less likely to adversely affect battery performance and are excellent in electrolytic solution resistance. Of the latter cationic polymerization types, alicyclic epoxy resins and polyester vinyl ether resins are also excellent in chemical resistance and moisture resistance and can be suitably used in the present invention. The cationic polymerization type has a high adhesive force because of a small volume change at the time of curing. For example, it has a characteristic that the adhesive strength to the foil is higher than that of a protective layer made of a tape or the like. Among these, it is particularly preferable.

  It is desirable that the protective layer has an electrical resistivity of 7.5 to 150 Ω · m.

  When the electrical resistivity of the protective layer is 7.5 to 150 Ω · m, it is possible to effectively prevent a sudden short circuit and perform a gentle discharge.

  The protective layer preferably has a thickness of 5 to 40 μm, more preferably 5 to 25 μm.

  By regulating the thickness of the protective layer made of a photocurable resin as described above, a protective layer having a certain resistance value can be easily obtained. That is, a protective layer having a desired semiconductivity can be obtained.

  Moreover, if the thickness of a protective layer is 5 micrometers or more, a photocurable resin can be apply | coated stably and it can apply | coat stably especially by an inkjet system. On the other hand, the thickness of the protective layer is restricted to 40 μm or less when the positive electrode active material layer or the negative electrode active material layer is formed to a thickness of about 40 μm (in the case of a thin-coated electrode). It is because it is necessary to form thinly so that it may not protrude in the thickness direction. Further, if the thickness of the protective layer is excessive, it becomes an insulating layer, that is, semiconductivity cannot be obtained.

  The resistance value of the protective layer is preferably 0.5 to 10Ω.

  If the resistance value of the protective layer is 0.5 to 10Ω, it is possible to effectively prevent a sudden short circuit and perform a gentle discharge. That is, the protective layer can function as a semiconductive layer having excellent safety.

  The protective layer is formed from the positive electrode lead or the negative electrode lead to the positive electrode active material layer or the negative electrode active material layer, and is formed on the positive electrode active material layer or the negative electrode active material layer. The thickness of the protective layer is smaller than the thickness of the protective layer formed on the positive electrode lead or the negative electrode lead, and the photocurable resin constituting the protective layer is the positive electrode active material layer or the negative electrode active material. It can be cured within the voids of the layer.

As described above, the protective layer is formed from the lead to the active material layer on at least one of the positive electrode side and the negative electrode side, and the thickness of the protective layer formed on the active material layer is formed on the lead. When the thickness of the protective layer is smaller than the thickness of the protective layer and the photocurable resin constituting the protective layer is cured in the voids of the active material layer, the battery is more excellent in battery characteristics and safer. Become.

  In order to prevent a sudden short circuit more reliably, it is preferable to provide a protective layer from the lead to the active material layer so that no gap is formed between the protective layer and the active material layer. However, when a protective layer is formed on the active material layer, only a part rises in the active material layer formation region, and when the laminated electrode body is in a state, the portion corresponding to the protective layer forming portion is There is a problem of partial thickening. As described above, when a part of the laminated electrode body is locally thickened, the constituent pressure applied from the exterior body or the like to the electrode body becomes non-uniform, and the charge / discharge reaction becomes non-uniform.

On the other hand, according to the configuration in which the photocurable resin constituting the protective layer is cured in the gaps of the positive electrode active material layer or the negative electrode active material layer as described above, the thickness of the protective layer on the active material layer It is possible to reduce the thickness of the laminated electrode body, and it is possible to avoid a partial thickening of the laminated electrode body. In the stacked battery having the above configuration, the photocurable resin applied on the active material layer is soaked into the active material layer, and the photocurable resin is cured while the photocurable resin is soaked in the active material layer. Is obtained. Accordingly, the cured photocurable resin exists in the voids in the active material layer, and the thickness of the protective layer formed on the active material layer is smaller than the thickness of the protective layer formed on the lead. . Moreover, the intensity | strength of an active material layer can be improved because a photocurable resin hardens within the space | gap of an active material layer. Therefore, it is possible to prevent the end of the active material layer from falling off.

The “thickness of the protective layer on the active material layer” is the thickness of the protective layer present on the surface of the active material layer,
It does not include a cured photocurable resin present in the active material layer. The thickness of the protective layer on the active material layer is preferably 1/3 or less of the thickness of the protective layer on the lead, more preferably 1/5 or less, and even more preferably 1/10 or less. . In order for the photocurable resin to penetrate into the active material layer, the viscosity of the photocurable resin at the time of coating, the density of the active material layer, the porosity of the active material layer, and the like may be controlled. . For example, when the protective layer is formed on the positive electrode side, the viscosity of the photocurable resin at the time of application is preferably 50 to 1500 cps, and the density of the positive electrode active material layer is 3.10 to 3.25 g / cm ³ . It is preferable.

  A gap may be formed between the positive electrode active material layer or the negative electrode active material layer and the protective layer.

  In the stacked battery, as described above, current collection is performed by joining a plurality of positive electrode leads and negative electrode leads extending from the stacked electrode body to the positive electrode current collector terminal and the negative electrode current collector terminal in a focused state. For this reason, the positive electrode lead and the negative electrode lead are inevitably bent at the extending base end portion (root portion) toward the converging position. The amount of bending is larger for the positive electrode lead or the negative electrode lead that is separated from the converging position. Of course, the greater the number of stacked electrode plates, the greater the distance from the converging position to the positive electrode or negative electrode lead that is farthest from the converging position. As a result, the amount of bending increases. In this case, when the protective layer is formed on the positive electrode lead or the negative electrode lead, the positive electrode lead or the negative electrode lead is not easily bent. Further, even if the positive electrode lead or the negative electrode lead is bent, it easily returns to the original posture due to the repulsive force, and it is difficult to stably hold the positive electrode lead or the negative electrode lead in the bent posture.

  Therefore, by providing a gap between the positive electrode active material layer or the negative electrode active material layer and the protective layer, the positive electrode lead or the negative electrode lead is extended to the base end portion while maintaining the effect of preventing a sudden short circuit by the protective layer. It becomes easy to bend at the (root part), and therefore its focusing becomes easy. Further, the positive electrode lead or the negative electrode lead can be stably held in a bent posture.

  In addition, when a gap is provided between the positive electrode active material layer or the negative electrode active material layer and the protective layer, the photocurable resin is not spread on the positive electrode active material layer or the negative electrode active material layer when the protective layer is formed. If not, it is desirable.

  A gap between the positive electrode active material layer or the negative electrode active material layer and the protective layer is preferably about 0.3 to 0.8 mm, more preferably about 0.3 to 0.5 mm.

  If the gap between the positive electrode active material layer or negative electrode active material layer and the protective layer is about 0.3 mm or more, the positive electrode lead or negative electrode lead can be bent sufficiently easily, and the photocurable resin It is possible to effectively avoid the positive electrode active material layer or the negative electrode active material layer. On the other hand, if this gap is about 0.8 mm or less, the effect of preventing a sudden short circuit by the protective layer can be maintained.

  It is desirable that the vertical dimension of the protective layer is about 5 to 8 mm. The “vertical dimension” of the protective layer is not a dimension in the direction perpendicular to the protruding direction of the positive electrode lead or the negative electrode lead (that is, a horizontal width) but a dimension in the direction along the protruding direction of the positive electrode lead or the negative electrode lead. is there.

  When the vertical dimension of the protective layer is less than 5 mm, the range in which the effect of preventing a sudden short circuit by the protective layer is insufficient, while when it exceeds 8 mm, the protective layer occupies more space than necessary and saves space. From the viewpoint of.

  It is desirable that the number of positive electrode plates stacked in the multilayer electrode body is 15 or more.

  When the number of stacked positive electrode plates in the laminated electrode body is 15 or more, the separator is liable to be displaced or twisted, so that the effect of forming the protective layer is particularly exerted.

  The width of the positive electrode lead or negative electrode lead on which the protective layer is formed is desirably 30 mm or more.

  When the width of the positive electrode lead or the negative electrode lead on which the protective layer is formed is 30 mm or more, the separator is liable to be displaced or twisted, so that the effect of forming the protective layer is particularly exerted.

  It is desirable that the protective layer is formed so as to protrude from the end of the separator to the outside.

  According to the above configuration, for example, even when one electrode (for example, the negative electrode plate) is displaced and protrudes to the outside of the separator, the one electrode and the other electrode (for example, the positive electrode plate) are separated by the protruding portion of the protective layer. Direct contact can be prevented. Further, by forming the protruding portion of the protective layer, it is not necessary to increase the size of the separator in preparation for the case where one electrode (for example, the negative electrode plate) is displaced.

  The protruding portion of the protective layer preferably protrudes about 2 to 6 mm outward from the separator, although it depends on the battery size and the like.

  It is desirable that an edge of the protective layer opposite to the side facing the positive electrode active material layer or the negative electrode active material layer is parallel to an edge of the positive electrode active material layer or the negative electrode active material layer.

  According to the above configuration, when the positive electrode plate and the negative electrode plate are laminated via the separator, particularly when the positive electrode plate or the negative electrode plate is accommodated in the bag-like separator, the edge of the separator and the edge of the protective layer are parallel to each other. By checking whether or not the positive electrode plate or the negative electrode plate and the separator are erroneously inclined to each other, this can be easily detected.

  Further, when the protrusion is formed on the protective layer, the edge of the protrusion (projection edge) is parallel to the edge of the positive electrode active material layer or the negative electrode active material layer. Then, since a parallel state can be seen by the edge of the protective layer at a position protruding outward from the edge of the separator, confirmation is easy.

In addition, in order to achieve the above object, a method for manufacturing a stacked battery according to the present invention includes:
Provided is a laminated electrode body in which a positive electrode plate having a positive electrode active material layer formed on a positive electrode current collector and a negative electrode plate having a negative electrode active material layer formed on a negative electrode current collector are laminated via a separator. The positive electrode plate and the negative electrode plate are each a manufacturing method of a laminated battery having a positive electrode lead and a negative electrode lead protruding from the edge portion, respectively.
In at least one of the positive electrode lead and the negative electrode lead, a photocurable resin is applied to a portion adjacent to the positive electrode active material layer or the negative electrode active material layer, and then irradiated with light to cure the photocurable resin. And a step of forming a protective layer.

  According to the configuration of the present invention, it is possible to obtain a stacked battery capable of effectively preventing the occurrence of a sudden short circuit in the positive electrode lead or the negative electrode lead by forming the protective layer. In addition, at this time, a protective layer is formed by applying a photocurable resin and irradiating light to cure the photocurable resin. Therefore, the protective layer can be formed by curing the resin in a short time. Therefore, the protective layer can be easily formed and the manufacturing cost can be reduced as compared with the case where a long drying process is performed.

  It is desirable that the protective layer has an electron conductivity lower than that of the positive electrode lead or the negative electrode lead on which the protective layer is formed and is non-insulating.

  This is for the same reason as described above.

  The protective layer is preferably configured to contain at least one of an epoxy acrylate resin, a urethane acrylate resin, an alicyclic epoxy resin, and a polyester vinyl ether resin.

  This is for the same reason as described above.

  The protective layer preferably has an electrical resistivity of 7.5 to 150 Ω · m.

  This is for the same reason as described above.

  The thickness of the protective layer is preferably 5 to 40 μm, more preferably 5 to 25 μm.

  This is for the same reason as described above.

  The resistance value of the protective layer is preferably 0.5 to 10Ω.

  This is for the same reason as described above.

  In the step of forming the protective layer, the photocurable resin is applied from the positive electrode lead or the negative electrode lead to the positive electrode active material layer or the negative electrode active material layer, and the positive electrode active material layer or the After the photocurable resin applied on the negative electrode active material layer has soaked into the positive electrode active material layer or the negative electrode active material layer, the photocurable resin is irradiated with light to irradiate the photocurable resin layer. The functional resin can be cured.

  This is for the same reason as described above. Here, it is not necessary for all of the photocurable resin applied on the active material layer to penetrate into the active material layer, and the thickness of the protective layer formed on the active material layer is the thickness of the protective layer formed on the lead. Of 1/3 or less, more preferably 1/5 or less, and still more preferably 1/10 or less. Note that the photocurable resin soaked in the active material layer is also cured in the active material layer by light irradiation.

  A gap can be formed between the positive electrode active material layer or the negative electrode active material layer and the protective layer.

  This is for the same reason as described above.

  The gap between the positive electrode active material layer or the negative electrode active material layer and the protective layer is preferably about 0.3 to 0.8 mm, more preferably about 0.3 to 0.5 mm.

  This is for the same reason as described above.

  It is desirable to apply the photocurable resin by an inkjet method.

  By applying the photocurable resin by an ink jet method, a thin and uniform protective layer can be accurately formed on the positive electrode lead or the negative electrode lead. Therefore, it is particularly advantageous when a protective layer having a small thickness is formed, or when a gap is formed between the positive electrode active material layer or the negative electrode active material layer and the protective layer. Moreover, since a photocurable resin can be applied thinly, it is easy to form a protective layer having a desired semiconductivity.

  According to the present invention, it is possible to effectively prevent occurrence of a short circuit or a sudden short circuit by forming a protective layer in a stacked battery, and it is possible to easily form a protective layer and reduce manufacturing costs. can do.

It is a figure which shows a part of laminated battery of this invention, Comprising: The same figure (a) is a top view of a positive electrode plate, the same figure (b) is a top view of a separator, The same figure (c) is a positive electrode plate inside. It is a top view which shows the bag-shaped separator arrange | positioned. It is a top view of the negative electrode plate used for the laminated battery of this invention. It is a top view which shows the condition which apply | coated the photocurable resin to the positive electrode lead. It is a top view which shows the condition which hardened photocurable resin and was used as the protective layer (semiconductive layer). It is a figure which shows typically the method of measuring the resistance value of a protective layer. It is a fragmentary top view which shows an example of the positive electrode plate which provided the clearance gap between the positive electrode active material layer and the protective layer. It is a top view which shows the bag-shaped separator by which the positive electrode plate used for the laminated battery of this invention was arrange | positioned inside. It is a disassembled perspective view of the laminated electrode body used for the laminated battery of this invention. It is a top view of the laminated electrode body used for the laminated battery of this invention. It is a top view which shows the state which joined the positive / negative electrode lead and the positive / negative current collector terminal. It is a perspective view of the laminated exterior body which accommodated the laminated electrode body. It is a top view which shows the condition where the photocurable resin was apply | coated on the positive electrode lead and positive electrode active material layer in the modification 1 of this invention. It is sectional drawing along XX of FIG. 12, FIG. 13 (a) shows the state immediately after apply | coating photocurable resin, FIG.13 (b) shows that photocurable resin is a positive electrode. It shows a state of being soaked in the active material layer. It is a top view of the positive electrode plate before apply | coating the photocurable resin in the modification 2 of this invention. It is a top view of the positive electrode plate after apply | coating the photocurable resin in the modification 2 of this invention.

  Hereinafter, the present invention will be described in more detail with reference to the drawings. However, the present invention is not limited to the following best modes, and can be implemented with appropriate modifications without departing from the spirit of the present invention. It is a thing.

[Preparation of positive electrode plate]
Mixing 90% by mass of LiCoO ₂ as a positive electrode active material, 5% by mass of carbon black as a conductive agent, 5% by mass of polyvinylidene fluoride (PVdF) as a binder, and an NMP solution as a solvent Thus, a positive electrode slurry was prepared. This positive electrode slurry was applied to both surfaces of an aluminum foil (thickness: 15 μm) as a positive electrode current collector. Thereafter, the solvent is dried and removed by heating, and after compression to a thickness of 0.1 mm with a roller, the width L1 = 85 mm and the height L2 = 85 mm as shown in FIG. The positive electrode plate 1 which cut | disconnected and has the positive electrode active material layer 1a on both surfaces of aluminum foil was produced. At this time, aluminum in which the positive electrode active material layer 1a having a width L3 = 30 mm and a height L4 = 20 mm from one end portion (left end portion in FIG. 1A) extending in the width L1 direction of the positive electrode plate 1 is not formed. The foil was extended to form a positive electrode lead 11.

(Production of negative electrode plate)
A negative electrode slurry was prepared by mixing 95% by mass of graphite powder as a negative electrode active material, 5% by mass of PVdF as a binder, and an NMP solution as a solvent. This negative electrode slurry was applied to both sides of a copper foil (thickness: 10 μm) as a negative electrode current collector. Thereafter, the solvent is removed by drying, and after compressing to a thickness of 0.08 mm with a roller, as shown in FIG. 2, it is cut so as to have a width L7 = 90 mm and a height L8 = 90 mm. The negative electrode plate 2 which has the negative electrode active material layer 2a on both surfaces was produced. At this time, the width L9 = 30 mm and the height L10 = 20 mm from the end (right end in FIG. 2) opposite to the positive electrode lead 11 formation side end of the positive electrode plate 1 on one side extending in the width direction of the negative electrode plate 2. A copper foil in which the negative electrode active material layer 2a was not formed was extended to form a negative electrode lead 12.

(Formation of protective layer)
As shown in FIG. 3, on both surfaces of the base end portion (root portion) of the positive electrode lead 11 of the positive electrode plate 1, that is, on both surfaces of the positive electrode lead 11, In FIG. 3, an ultraviolet curable resin is formed so that the lateral width L3 = 30 mm and the height (vertical dimension) L11 = 5 mm outward along the positive electrode lead 11 formation side edge of the positive electrode plate 1. 13P was applied by an inkjet method. An alicyclic epoxy resin was used as the ultraviolet curable resin 13P.

Thereafter, the ultraviolet curable resin 13P applied to the positive electrode lead 11 was cured by irradiating ultraviolet rays with a high-pressure mercury lamp, thereby forming a protective layer (semiconductive layer) 13A as shown in FIG. The curing conditions were an ultraviolet illuminance of 130 mW / cm ² and an irradiation time of 10 seconds (exposure amount 1300 mJ / cm ² ). The thickness after curing, that is, the thickness of the protective layer 13A was set to 10 μm on one side.

[Measurement of resistance value of protective layer]
As schematically shown in FIG. 5, an aluminum foil 34 is overlaid on the protective layer 13 </ b> A formed on the positive electrode lead 11 of the positive electrode plate 1, and this overlapped portion is formed from two glass plates 35 from both sides. , 35 and fixed with clips (not shown). Here, the aluminum foil 34 was in contact with the entire upper surface of the protective layer 13A. Subsequently, the resistance value between the positive electrode plate 1 (positive electrode lead 11) and the aluminum foil 34 was measured by a tester 36 connected to the positive electrode plate 1 (positive electrode lead 11) and the aluminum foil 34. As a result, it was confirmed that the resistance value of the protective layer 13A on one side was 5Ω.

[Production of positive electrode plate according to another embodiment]
On the other hand, as shown in FIG. 6, except that the gap S1 = 0.5 mm is provided between the positive electrode active material layer 1a and the protective layer 13B, all the same as in the case of the positive electrode plate 1 described above, A positive electrode plate 1D according to the embodiment was prepared.

[Production of bag-shaped separator with positive electrode plate arranged inside]
After arranging the positive electrode plate 1 between two rectangular polypropylene (PP) separators 3a (thickness 30 μm) having a width L5 = 90 mm and a height L6 = 90 mm as shown in FIG. As shown in FIG. 1 (c), the four sides (peripheral portion; excluding the positive electrode lead 11 extending portion) of the separator 3a are thermally welded and joined to form the joint portions 4 extending along the respective sides. Then, a bag-like separator 3 in which the positive electrode plate 1 was housed and arranged was produced.

  At this time, as shown also in FIG. 7, the joining portions 4 of the separator 3 a are formed intermittently (so that a plurality are connected in a row at intervals), and the proportion of the joining regions of the joining portions 4 is as follows. 50%.

  At this time, as shown in FIG. 7, the protective layer 13A protrudes L12 = 2.5 mm outward from the separator 3a (upward in FIG. 7), thereby forming a protruding portion 13E. Further, at this time, the edge (projection edge) E1 of the protrusion 13E is parallel to the positive electrode lead 11 side edge (upper edge in FIG. 7) E2 of the positive electrode active material layer 1a in the positive electrode plate 1. When the positive electrode plate 1 is disposed between the separators 3a to produce the bag-shaped separator 3, the edge (upper edge in FIG. 7) E3 and the edge of the protrusion 13E in the separator 3a. By confirming whether or not E1 is parallel, it is confirmed whether or not the positive electrode plate 1 and the separator 3a are correctly arranged without being inclined with respect to each other.

(Production of laminated electrode body)
Thirty-five bag-like separators 3 and 36 negative-electrode plates 2 with the positive electrode plate 1 disposed therein were prepared, and the bag-like separators 3 and the negative electrode plates 2 were alternately laminated as shown in FIG. At that time, the negative electrode plate 2 was positioned at both ends in the stacking direction. Next, as shown in FIG. 9, both end surfaces of this laminate were connected with an insulating tape 26 for maintaining the shape to obtain a laminate electrode assembly 10.

[Welding of current collector terminal]
As shown in FIG. 10, a positive electrode current collecting terminal 15 made of an aluminum plate having a width of 30 mm and a thickness of 0.4 mm and a copper plate having a width of 30 mm and a thickness of 0.4 mm are provided at the extended ends of the positive electrode lead 11 and the negative electrode lead 12. Each of the negative electrode current collecting terminals 16 formed by welding was welded and joined at a welding point 14 by an ultrasonic welding method.

  Note that reference numeral 31 shown in FIG. 10 and other drawings is a belt-like shape along the width direction of the positive and negative current collecting terminals 15 and 16 in order to ensure hermeticity when heat-sealing an exterior body 18 to be described later. The resin sealing material (glue material) molded so as to be fixed to is indicated.

[Encapsulation in exterior body]
As shown in FIG. 11, the laminated electrode body 10 is inserted into an exterior body 18 composed of a laminate film 17 that has been previously molded so that the electrode body can be accommodated, and only the positive electrode current collector terminal 15 and the negative electrode current collector terminal 16 are present. Of the three sides other than the side where the positive electrode current collecting terminal 15 and the negative electrode current collecting terminal 16 are projected from the exterior body 18, three sides were heat-sealed except for one side.

[Encapsulation and sealing of electrolyte]
LiPF ₆ is 1M (moles) in a mixed solvent in which ethylene carbonate (EC) and methyl ethyl carbonate (MEC) are mixed at a volume ratio of 30:70 from one side where the outer package 18 is not thermally welded. The battery was fabricated by injecting an electrolytic solution dissolved at a ratio of 1 / liter) and finally thermally welding one side that was not thermally welded.

[Modification 1]
A protective layer is formed from the lead to the active material layer, and the thickness of the protective layer formed on the active material layer is smaller than the thickness of the protective layer formed on the lead, and the photo-curing property constituting the protective layer A mode in which the resin is cured in the voids of the active material layer will be described. Although it is applicable to either one or both of the positive electrode side and the negative electrode side, description will be made using the positive electrode side.

As shown in FIGS. 12 and 13, an ultraviolet curable resin 13 </ b> P was applied from the base end portion (root portion) of the positive electrode lead 11 of the positive electrode plate 1 to the positive electrode active material layer 1 a by an inkjet method. Here, the UV curable 13P is formed on both surfaces of the positive electrode lead 11 along the boundary between the formed part and the non-formed part of the positive electrode active material layer 1a, the width L3 = 30 mm, and the height (vertical dimension) L13 = 6 mm (positive electrode lead). 11 is 3 mm, and the positive electrode active material layer 1 a is 3 mm). A urethane acrylate resin was used as the ultraviolet curable resin 13P. Further, in order to soak the ultraviolet curable resin 13P into the positive electrode active material layer 1a, the viscosity of the ultraviolet curable resin 13P during application was set to 1000 cps, and the density of the positive electrode active material layer was set to 3.20 g / cm ³ .

As shown in FIG. 13A, the ultraviolet curable resin 13P was applied from the positive electrode lead 11 to the positive electrode active material layer 1a, and as shown in FIG. 13B, the ultraviolet curable resin 13P was applied on the positive electrode active material layer 1a. The ultraviolet curable resin 13P penetrates into the positive electrode active material layer 1a. In FIG. 13B, 13P ′ indicates an ultraviolet curable resin soaked in the positive electrode active material layer 1a. Thereafter, the ultraviolet curable resins 13P and 13P ′ were cured by irradiating the region where the ultraviolet curable resin 13P was applied and the region where the ultraviolet curable resin 13P ′ was present in the positive electrode active material layer 1a with a high pressure mercury lamp. . The curing conditions were an ultraviolet illuminance of 130 mW / cm ² and an irradiation time of 10 seconds (exposure amount 1300 mJ / cm ² ). The thickness of the protective layer formed on the lead after curing was 10 μm, and the thickness of the protective layer formed on the positive electrode active material layer 1a after curing was 3 μm. Further, after curing, it was confirmed by a scanning electron microscope (SEM) that the ultraviolet curable resin was cured inside the active material. Using the positive electrode plate thus produced, a stacked battery can be produced by the above-described method.

[Modification 2]
As shown in FIG. 14, the positive electrode active material layer 1a is formed up to the region of the positive electrode lead 11, and then UV curable 13P is applied and cured in the same manner as in the first modification as shown in FIG. A protective layer can be provided. With such a configuration, it is possible to prevent a gap from being formed between the protective layer and the active material layer without reducing the battery capacity, and a more safe stacked battery can be obtained. 14 and 15, K represents a boundary line between the formed part and the unformed part of the positive electrode active material layer 1a.

[Other matters]
(1) In the above-described embodiment, a corner configured to form a rectangular outer shape by enclosing the laminated electrode body 10 formed by laminating the square positive and negative electrode plates 1 and 2 and the separator 3a in the laminate exterior body 18. Although a stacked battery of a type has been produced, a battery can or the like may be used as the outer package.

(2) In the above embodiment, the joining portion 4 of the bag-like separator 3 is formed by thermal welding. However, as a joining method in the joining portion, in addition to thermal welding, for example, ultrasonic welding or joining by an adhesive is used. Etc. may be used.

(3) In the above-described embodiment, the positive electrode plate 1 is housed in the bag-shaped separator 3, but the negative electrode plate may be housed in the bag-shaped separator. However, since the negative electrode plate is usually prepared with a size larger than that of the positive electrode plate, it is desirable from the viewpoint of space saving that the positive electrode plate is accommodated in a bag-like separator.

(4) In the above embodiment, the bag-shaped separator 3 is configured in a bag shape by joining the four sides (peripheral portions) of the two separators 3a. You may make it comprise in a bag shape by bend | folding a separator and joining 3 sides (peripheral part) other than a bending part.

(5) The positive electrode active material is not limited to the above-described lithium cobalt oxide, and lithium composite oxide containing cobalt such as cobalt-nickel-manganese, aluminum-nickel-manganese, aluminum-nickel-cobalt, nickel, or manganese. Or a spinel type lithium manganate may be used.

(6) As the negative electrode active material, in addition to graphite such as natural graphite and artificial graphite, graphite, coke, tin oxide, metal lithium, silicon, and a mixture thereof can be used to insert and desorb lithium ions. It doesn't matter.

(7) The electrolyte solution is not particularly limited to that shown in the present embodiment, and examples of the supporting salt include LiBF ₄ , LiPF ₆ , LiN (SO ₂ CF ₃ ) ₂ , and LiN (SO ₂ C ₂ F). ₅ ) ₂ , LiPF _6-x (C _n F _{2n + 1} ) _x [where 1 <x <6, n = 1 or 2] and the like can be used, and one or more of these can be used in combination. The concentration of the supporting salt is not particularly limited, but is preferably 0.8 to 1.8 mol per liter of the electrolyte. In addition to the above EC and MEC, the solvent species include carbonate solvents such as propylene carbonate (PC), γ-butyrolactone (GBL), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), and diethyl carbonate (DEC). More preferably, a combination of a cyclic carbonate and a chain carbonate is desirable.

  The present invention can be suitably applied to, for example, a power source mounted on a robot or an electric vehicle, a power source for high output such as a backup power source (for example, a large-capacity prismatic battery, etc.). It is possible to apply to various uses.

1: Positive electrode plate 1a: Positive electrode active material layer 11: Positive electrode lead 13A: Protective layer 3a: Separator

Claims (17)

Provided is a laminated electrode body in which a positive electrode plate having a positive electrode active material layer formed on a positive electrode current collector and a negative electrode plate having a negative electrode active material layer formed on a negative electrode current collector are laminated via a separator. The positive electrode plate and the negative electrode plate are each a stacked battery having a positive electrode lead and a negative electrode lead protruding from the edge portion, respectively.
A laminated battery, wherein a protective layer made of a photocurable resin is formed in a portion adjacent to the positive electrode active material layer or the negative electrode active material layer in at least one of the positive electrode lead and the negative electrode lead.   The stacked battery according to claim 1, wherein the protective layer has a lower electronic conductivity than the positive electrode lead or the negative electrode lead on which the protective layer is formed, and is non-insulating.   The stacked battery according to claim 1 or 2, wherein the protective layer includes at least one of an epoxy acrylate resin, a urethane acrylate resin, an alicyclic epoxy resin, and a polyester vinyl ether resin.   The stacked battery according to claim 2 or 3, wherein the protective layer has an electrical resistivity of 7.5 to 150 Ω · m.   The laminated battery according to any one of claims 2 to 4, wherein the protective layer has a thickness of 5 to 40 µm.   The stacked battery according to claim 2, wherein the protective layer has a resistance value of 0.5 to 10Ω.   The protective layer is formed from the positive electrode lead or the negative electrode lead to the positive electrode active material layer or the negative electrode active material layer, and is formed on the positive electrode active material layer or the negative electrode active material layer. The thickness of the protective layer is smaller than the thickness of the protective layer formed on the positive electrode lead or the negative electrode lead, and the photocurable resin constituting the protective layer is the positive electrode active material layer or the negative electrode active material. The laminated battery according to any one of claims 1 to 6, which is cured in a void of the layer.   The stacked battery according to any one of claims 1 to 6, wherein a gap of 0.3 to 0.8 mm is formed between the positive electrode active material layer or the negative electrode active material layer and the protective layer. Provided is a laminated electrode body in which a positive electrode plate having a positive electrode active material layer formed on a positive electrode current collector and a negative electrode plate having a negative electrode active material layer formed on a negative electrode current collector are laminated via a separator. The positive electrode plate and the negative electrode plate are each a manufacturing method of a laminated battery having a positive electrode lead and a negative electrode lead protruding from the edge portion, respectively.
In at least one of the positive electrode lead and the negative electrode lead, a photocurable resin is applied to a portion adjacent to the positive electrode active material layer or the negative electrode active material layer, and then irradiated with light to cure the photocurable resin. A method for producing a stacked battery, comprising the step of forming a protective layer.   The method for manufacturing a stacked battery according to claim 9, wherein the protective layer has an electron conductivity lower than that of the positive electrode lead or the negative electrode lead on which the protective layer is formed and is non-insulating.   The laminated type according to claim 9 or 10, wherein the protective layer includes at least one of an epoxy acrylate resin, a urethane acrylate resin, an alicyclic epoxy resin, and a polyester vinyl ether resin. Battery manufacturing method.   The method for manufacturing a stacked battery according to claim 10 or 11, wherein the protective layer has an electrical resistivity of 7.5 to 150 Ω · m.   The method for manufacturing a stacked battery according to any one of claims 10 to 12, wherein the protective layer has a thickness of 5 to 40 µm.   The method for manufacturing a stacked battery according to claim 10, wherein the protective layer has a resistance value of 0.5 to 10Ω.   In the step of forming the protective layer, the photocurable resin is applied from the positive electrode lead or the negative electrode lead to the positive electrode active material layer or the negative electrode active material layer, and the positive electrode active material layer or the After the photocurable resin applied on the negative electrode active material layer has soaked into the positive electrode active material layer or the negative electrode active material layer, the photocurable resin is irradiated with light to irradiate the photocurable resin layer. The method for manufacturing a laminated battery according to claim 9, wherein the functional resin is cured.   The method for manufacturing a stacked battery according to any one of claims 9 to 14, wherein a gap of 0.3 to 0.8 mm is formed between the positive electrode active material layer or negative electrode active material layer and the protective layer. .   The method for producing a laminated battery according to any one of claims 9 to 16, wherein the photocurable resin is applied by an inkjet method.

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