JP5375179B2 - Insulation degradation site identification method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of readily specifying an insulation degraded portion of an electrochemical cell constituted of an outer package body formed by at least sequentially laminating a base material layer, a metal foil layer and a heat-adhesive resin layer and of clarifying in detail the cause of insulation degradation. <P>SOLUTION: The method of specifying the insulation degraded portion includes the base material layer removing step of removing the base material layer 171 by melting it with a strong acid in the vicinity of a portion of the outer package body 170 where the cause of the insulation degradation is expected to be present and the metal foil layer removing step of removing the metal foil layer 172 by melting it with a second strong acid after removal of the base material layer. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention easily detects an insulating degradation portion of an electrochemical cell composed of an exterior body constituted by laminating at least a base material layer, a metal foil layer, and a heat-adhesive resin layer, and insulates it. The present invention relates to a method capable of elucidating the cause of sex decline in detail.

The lithium ion battery is also referred to as a lithium secondary battery, and includes a liquid, gel-like, or polymer polymer electrolyte, and a positive electrode / negative electrode active material made of a polymer polymer. In this lithium ion battery, the lithium atom (Li) in the lithium transition metal oxide, which is the positive electrode active material, is charged as lithium ion (Li ⁺ ) during charging and enters the carbon layer of the negative electrode (intercalation). This is a battery in which charge / discharge reaction proceeds when ions (Li ⁺ ) are separated from the carbon layer (deintercalation) and move to the positive electrode to become the original lithium compound. From the nickel-cadmium battery and the nickel-hydrogen battery The output voltage is high, the energy density is high, and the apparent discharge capacity is reduced by repeating shallow discharge and recharging, so that there is no so-called memory effect.

  In addition, the configuration of the lithium ion battery is composed of a positive electrode current collector / positive electrode active substance layer / electrolyte layer / negative electrode active substance layer / negative electrode current collector and an outer package that wraps these, and as a packaging material for forming the outer package, Instead of a metal can, a packaging material composed of a laminate made of a multilayer film tends to be used as an exterior body.

  Specifically, a packaging material made of at least a base material layer, a metal foil layer, and a heat-adhesive resin layer is processed into a bag shape, and a pouch-type battery exterior body or packaging that houses the battery body inside The material is pressed to form a recess, and an embossed type battery exterior body that houses the battery body inside the recess can be produced.

  9 is a perspective view of a lithium ion battery 251 using an embossed type battery exterior body 270. FIG. 10 is an exploded perspective view of the lithium ion battery 251 shown in FIG. It is sectional drawing in BB 'of the lithium ion battery 251 shown in FIG. As shown in FIGS. 9 to 11, a lithium ion battery 251 using a battery outer body 270 (see FIG. 11) composed of at least a base material layer 271, a metal foil layer 272, and a thermal adhesive resin layer 275 is embossed. The battery body outer body is housed by storing the lithium ion battery main body 252 in the tray 270t in which the section is formed, stacking the heat-adhesive resin layers 275 of the tray 270t and the sheet 270s, and heat-sealing the heat seal section 270a. The lithium ion battery main body 252 can be hermetically stored in the 270 (see FIG. 10).

  The lithium ion battery main body 252 includes a positive electrode made of a positive electrode active material and a positive electrode current collector, a negative electrode made of a negative electrode active material and a negative electrode current collector, and an electrolyte filled between the positive electrode and the negative electrode (both shown). ) And a metal terminal 254 that is connected to the positive electrode and the negative electrode in the cell and protrudes outside the battery exterior body 270.

  At this time, as shown in FIG. 11, the lithium ion battery main body 252 generates heat due to long-term use or rapid charging of the lithium ion battery 251, and is arranged in the innermost layer of the outer package 270, as shown in FIG. 11. A part of the heat-adhesive resin layer 275 may melt. At this time, the electrolyte filled in the exterior body 270 may permeate into the metal foil layer 272 from a part of the molten heat-adhesive resin 275, and the lithium ion battery 251 may be short-circuited.

  Further, when the lithium ion battery main body 252 is hermetically housed in the exterior body 270, the electrode active material constituting the lithium ion battery main body 252 is bitten between the tray 270t and the sheet 270s in the heat seal portion 270a. In the heat seal part 270a, the electrode active material may break a part of the heat-adhesive resin layer 275 disposed on the innermost layer of the outer package 270. At this time, the electrolyte filled in the exterior body 270 may permeate into the metal foil layer 272 from a part of the broken thermal adhesive resin 275, and the lithium ion battery 251 may be short-circuited.

  Further, the heat sealing portion 270a of the exterior body 270 can be bent to improve the output per volume of the lithium ion battery 251. At this time, cracks and pinholes occurred in the bent portion of the thermal adhesive resin layer 275. In such a case, the electrolyte may permeate into the metal foil layer 272 from the portion, and the lithium ion battery 251 may be short-circuited.

  Further, as shown in FIG. 9, the thermal adhesive resin layer 275 disposed in the innermost layer is heat-sealed around the metal terminal 254 with the metal terminal film 254 sandwiched therebetween, but is thermally bonded around the metal terminal 254. When the conductive resin layer 275 is thinned by heat and pressure during heat sealing and the metal terminal 254 and the metal foil layer 272 are in contact, the lithium ion battery 251 may be short-circuited.

  Similarly, when the temperature inside the exterior 270 rises due to overcharge of the lithium ion battery 251, etc., the metal terminal 254 generates heat, and the heat disposed in the innermost layer of the exterior body 270 in the sandwiched portion of the metal terminal 254. When the adhesive resin layer 275 melts and the metal terminal 254 and the metal foil layer 272 constituting the exterior body 270 come into contact, the lithium ion battery 251 may be short-circuited.

  Further, when the temperature inside the exterior 270 rises due to overcharge of the lithium ion battery 251, etc., the metal terminal 254 generates heat, and the thermal bonding disposed on the innermost layer of the exterior body 270 at the sandwiched portion of the metal terminal 254. When the conductive resin layer 275 melts and the metal terminal 254 and the metal foil layer 272 constituting the exterior body 270 come into contact with each other, the lithium ion battery 251 may be short-circuited.

  As described above, when the lithium ion battery 251 is used or manufactured, a short circuit occurs due to the melting, breaking, cracking, or pinhole of the heat-adhesive resin layer 275, and the insulation of the lithium ion battery 251 is reduced. Was a problem.

  In order to investigate the cause of the decrease in the insulation property of the lithium ion battery 251 with respect to such a problem, it is first necessary to identify the insulation decrease portion. However, the metal foil layer 272 that constitutes the exterior body 270 is impermeable, and it is not possible to identify the insulation degradation site by visually observing the heat-adhesive resin layer 275 from outside the exterior body 270. Therefore, conventionally, the thermal adhesive resin layer 275 is peeled off from the metal foil layer 272 by focusing on a site where a cause of a short circuit such as a crack or a pinhole is likely to occur, and then the thermal adhesive resin layer 275 is removed with a microscope or the like. I was looking for a site with reduced insulation. Further, Patent Document 1 describes a method in which a metal is deposited on a metal foil layer constituting an exterior body by a plating method, and the presence or absence of the formation of the metal deposit is confirmed by visual observation or the like to specify a portion having reduced insulation. It was.

JP 2007-257974 A

  However, focusing on areas where cracks and pinholes are likely to cause short-circuits and searching for areas with poor insulation with a microscope or the like is a time-consuming task, and there is a risk of overlooking areas with poor insulation. It was. In addition, in the method for detecting an insulation degradation site described in Patent Document 1, since metal is deposited at a site that causes a short circuit, the site of the short circuit can be identified, but the cause of the short circuit is the thermal adhesive resin layer. It was not possible to elucidate the specific cause of whether it was caused by cracks, pinholes or melting. Also, in any of the above methods for detecting a reduced insulation property, after disassembling the lithium ion battery, it is necessary to peel off the thermal adhesive resin layer and the metal foil layer and observe the thermal adhesive resin layer. It was a laborious work.

  Therefore, in view of the above problems, the present invention provides an insulating degradation portion of an electrochemical cell composed of an exterior body configured by laminating at least a base material layer, a metal foil layer, and a thermoadhesive resin layer. It is an object of the present invention to provide a method capable of easily identifying and clarifying in detail the cause of insulation deterioration.

  In order to achieve the above object, the insulation lowering site identification method according to the first configuration of the present invention is configured by laminating at least a base material layer, a metal foil layer, and a thermal adhesive resin layer sequentially. An electrochemical cell body including a positive electrode composed of a positive electrode active material and a positive electrode current collector, a negative electrode composed of a negative electrode active material and a negative electrode current collector, and an electrolyte filled between the positive electrode and the negative electrode inside the outer package, And a method for identifying a reduced insulating portion of an electrochemical cell configured by sealing and storing so that a tip of a metal terminal connected to each of the negative electrode protrudes to the outside, and there is a cause of a reduced insulating property in an exterior body Then, in the vicinity of the expected site, after the base material layer removing step of dissolving and removing the base material layer using the first strong acid, and after the base material layer removing step, the metal foil layer is dissolved using the second strong acid. A metal foil layer removing step to be removed, and That.

  Moreover, the 2nd structure of this invention is the said insulation fall site | part identification method, and measures the electrical resistance value between the metal foil layer which comprises an exterior body, and a metal terminal before a base material layer removal process. It has the process.

  Further, the third configuration of the present invention is the above-described method for specifying a reduced insulation site, after the occurrence of a short circuit is confirmed in the first step, and before the base material layer removing step, two metal foil layers are provided. A second step of forming an insulating band to insulate the region, and a third step of measuring an electrical resistance value between the two regions of the insulated metal foil layer and the metal terminal after the second step. The insulating band is formed by dissolving and removing the base material layer constituting the exterior body using the first strong acid and then dissolving and removing the metal foil layer constituting the exterior body using the second strong acid. It is characterized by.

  Moreover, the 4th structure of this invention is the metal foil layer and metal terminal which comprise an exterior body in the area | region which has not removed the metal foil layer after the metal foil layer removal process in the said insulation fall site | part identification method. It has the 4th process of measuring the electrical resistance value between.

  Moreover, the 5th structure of this invention is a 5th structure which forms a metal deposit using a plating method in the site | part which removed the metal foil layer after the metal foil layer removal process in the said insulation fall site | part identification method. It has the process.

  In addition, according to a sixth configuration of the present invention, in the above insulation lowering site specifying method, the base material layer is disposed on the outer layer side of the exterior body, and the second base material is disposed on the inner layer side of the exterior body. When having a base material layer, the first base material layer is a polyethylene terephthalate film or a polyethylene naphthalate film, and the second base material layer is a biaxially stretched nylon film, a notch penetrating the first base material layer It is characterized by having the notch formation process which forms in a base material layer before a base material layer removal process.

  The seventh configuration of the present invention is characterized in that, in the above insulation lowering site specifying method, the first strong acid is hydrofluoric acid.

  In addition, an eighth configuration of the present invention is characterized in that, in the above-described method for specifying an insulating decrease site, the second strong acid is a hydrochloric acid solution.

  According to the first configuration of the present invention, the positive electrode active material and the positive electrode current collector are disposed inside the outer package configured by laminating at least a base material layer, a metal foil layer, and a heat-adhesive resin layer. An electrochemical cell body including a positive electrode comprising a negative electrode comprising a negative electrode active material and a negative electrode current collector, and an electrolyte filled between the positive electrode and the negative electrode, and the tip of a metal terminal connected to each of the positive electrode and the negative electrode is external In an electrochemical cell configured to be hermetically housed so as to protrude into the base, a base layer that dissolves and removes the base material layer using the first strong acid in the vicinity of a portion that is expected to cause a decrease in insulation in the exterior body. By the material layer removing step, the metal foil layer in the vicinity of the site can be exposed.

  Next, in the metal foil layer removing step of dissolving and removing the metal foil layer using the second strong acid, the heat-adhesive resin layer is exposed outside the exterior body at the site where the metal foil layer is removed. Thereby, while being able to search and specify the insulation fall site | part which generate | occur | produced in the thermoadhesive resin layer from the exterior body exterior, the cause of insulation fall can be clarified by visual observation. In addition, in the case where the insulation lowering portion is not found in the vicinity of the portion where the insulation lowering portion is expected to exist in the exterior body, the base material layer removal step and the metal foil layer removal step are performed in this order in other regions. It is possible to find out the insulation lowering portion by repeating the above.

  According to the second configuration of the present invention, in the insulation lowering site identification method, by measuring the electrical resistance value between the metal foil layer constituting the exterior body and the metal terminal before the base material layer removing step, It is possible to detect the occurrence of a short circuit in the electrochemical cell. And when it detects that there is no short circuit generation | occurrence | production, it can avoid performing an unnecessary base material layer removal process and metal foil layer removal process.

  According to the 3rd structure of this invention, in the said insulation fall site | part identification method, the 2nd process of forming the insulation band which insulates a metal foil layer into two area | regions, and two area | regions of the insulated metal foil layer In the third step of measuring the electrical resistance value between the metal terminal and the metal terminal, a resistance value indicating conduction between the metal terminal in one of the two regions of the insulated metal foil layer is indicated. In addition, it can be expected that there is an insulating decrease in the region of the metal foil layer that has been energized. Thereby, an insulation fall site | part can be specified easily.

  In addition, in the region of the metal foil layer where the resistance value indicating energization is indicated, the second step and the third step are repeated again to limit the region where the insulation lowering portion is expected to exist. Can do. Accordingly, it is possible to more easily identify the insulation lowering portion.

  According to the fourth configuration of the present invention, in the insulation lowering portion specifying method, the electrical resistance value between the metal foil layer and the metal terminal in the region where the metal foil layer is not removed is measured after the metal foil layer removing step. Then, when a resistance value indicating energization is indicated, it can be expected that there is an insulating degradation portion in a region indicating energization. Thereby, an insulation fall site | part can be specified easily. In addition, in the region where the metal foil layer has been removed, there is no need to search for a region where the insulation is lowered.

  On the other hand, in the region where the metal foil layer has not been removed, if the resistance value indicating current conduction between the metal foil layer constituting the exterior body and the metal terminal is not indicated, the region where the metal foil layer has been removed has reduced insulation. Can be expected to exist.

  According to the fifth configuration of the present invention, in the above-described insulation lowering part specifying method, after the heat-adhesive resin layer is exposed to the outside of the exterior body by the metal foil layer removing step, the plating method is performed at the part where the metal foil layer is removed. A fifth step of forming a metal precipitate using Thereby, in the part where this metal foil layer is removed, when the insulation lowering part such as a crack or pinhole leading from the inside of the exterior body to the exterior of the exterior body is generated on the thermoadhesive resin layer, the plating method is used. A metal precipitate can be formed inside the insulation lowering portion such as a crack or a pinhole to identify the insulation lowering portion. In addition, if metal deposits are not formed by plating at the site where the metal foil layer has been removed, insulation such as cracks or pinholes from the interior of the exterior body to the exterior of the exterior body on the heat-adhesive resin layer at that location. It can be predicted that no sex-reduced site has occurred. As a specific plating method, an electrochemical cell from which the metal foil layer of the outer package has been removed is immersed in a plating solution, the cathode terminal is connected to the metal terminal of the negative electrode of the electrochemical cell, and the anode plate is placed in the plating solution. Immersion is performed by applying a direct current between the cathode terminal and the anode plate. At this time, the metal terminal of the electrochemical cell connected to the cathode terminal is electrically connected to the electrolyte filled in the exterior body, and the electrolyte functions as a cathode plate. As a result, in the case where cracks or pinholes such as cracks or pinholes leading from the inside of the exterior body to the exterior of the exterior body have occurred on the thermal adhesive resin layer, the plating solution is insulated from the exterior of the exterior body in the plating solution. It penetrates to the electrolyte filled in the exterior body through the lowered portion. When a direct current is passed between the cathode terminal and the anode plate, metal is deposited from the plating solution that has penetrated to the electrolyte surface, and metal deposits are formed inside the insulation lowering sites such as cracks or pinholes. Therefore, if the heat-adhesive resin layer is made of a permeable resin, the cause of the deterioration of insulation such as cracks or pinholes can be easily clarified by visually observing the shape of the formed metal deposits from outside the exterior body. can do. In addition, the said method shows an example of the plating method, It is not limited to this.

  According to the 6th structure of this invention, in the said insulation fall site | part identification method, the 2nd group by which a base material layer is distribute | arranged to the inner layer side of a 1st base material layer distribute | arranged to the outer layer side of an exterior body, and the exterior body When having a material layer, the first base material layer is a polyethylene terephthalate film or a polyethylene naphthalate film, and the second base material layer is a biaxially stretched nylon film, a notch penetrating the first base material layer is formed. By performing the notch formation process formed in a base material layer before a base material layer removal process, in a base material layer removal process, a 1st strong acid osmose | permeates from the site | part which formed the notch, and comprises a 2nd base material layer. The adhesive layer for bonding the biaxially stretched nylon film, the polyethylene terephthalate film or the polyethylene naphthalate film and the metal foil layer can be dissolved and removed. Accordingly, the polyethylene terephthalate film or the polyethylene naphthalate film can be easily removed from the outer package without dissolving the polyethylene terephthalate film or the polyethylene naphthalate film.

  According to the seventh configuration of the present invention, in the above-described method for specifying an insulation lowering site, the first strong acid is hydrofluoric acid, so that the base material layer is made of a resin having high chemical resistance such as a polyamide-based resin. Even if it is, it can be dissolved and removed.

  According to the 8th structure of this invention, in the said insulation fall site | part identification method, even when the metal foil layer is comprised with aluminum, it can melt | dissolve and can be removed by a 2nd strong acid being hydrochloric acid solution.

The perspective view of the lithium ion battery used for the insulation fall site | part identification method of this invention Cross section of the lithium ion battery shown in FIG. The top view of the lithium ion battery used for the insulation fall site | part identification method of this invention The top view of the lithium ion battery used for the insulation fall site | part identification method of this invention The top view of the lithium ion battery used for the insulation fall site | part identification method of this invention Cross section of the lithium ion battery shown in FIG. Cross section of the lithium ion battery shown in FIG. Cross section of the lithium ion battery shown in FIG. Sectional drawing which shows typically the apparatus used for the insulation fall site | part identification method of this invention Sectional view of the lithium ion battery shown in FIG. Lithium ion battery perspective view The perspective view which decomposes | disassembles and shows the lithium ion battery shown in FIG. Cross-sectional view of the lithium ion battery shown in FIG.

  The present invention easily specifies an insulating degradation portion of an electrochemical cell composed of an exterior body constituted by laminating at least a base material layer, a metal foil layer, and a thermal adhesive resin layer, and insulating It is a method that can elucidate in detail the cause of sex decline. An embodiment of the method for identifying a reduced insulation site according to the present invention will be described in more detail with reference to the drawings. Note that the description of the portions common to FIGS. 9 to 11 in the conventional example is omitted.

  First, a lithium ion battery that uses the insulation lowering site specifying method of the present embodiment will be described. In addition, the lithium ion battery using the insulation lowering site specifying method of the present embodiment is an embodiment included in the “electrochemical cell” of the present invention. In addition to the lithium ion battery, a capacitor, an electric double layer capacitor is used as an outer package. For example, the method for identifying a reduced insulation site according to the present embodiment can be used for an electrochemical cell containing an electrochemical cell main body.

  1 is a perspective view of the lithium ion battery 151, and FIG. 2 is a cross-sectional view taken along line A-A 'of the lithium ion battery 151 shown in FIG. As shown in FIGS. 1 and 2, the lithium ion battery 151 is configured by sealing and housing a lithium ion battery main body 152 inside an exterior body 170. At this time, the exterior body 170 is configured by sequentially laminating at least a base material layer 171, a metal foil layer 172, and a thermal adhesive resin layer 175. The exterior body 170 accommodates the lithium ion battery main body 152 inside the tray 170t in which the embossed portion is formed, and the thermal adhesive resin layers 175 of the tray 170t and the sheet 170s are overlapped with each other. The lithium ion battery main body 152 is hermetically housed inside the exterior body 170 by heat-sealing the seal portion 170a).

  The lithium ion battery main body 152 includes a positive electrode composed of a positive electrode active material and a positive electrode current collector, a negative electrode composed of a negative electrode active material and a negative electrode current collector, and an electrolyte filled between the positive electrode and the negative electrode (both not shown). And the metal terminal 154 connected to the positive electrode and the negative electrode in the cell. When the lithium ion battery main body 152 is hermetically housed in the exterior body 170, the metal terminal 154 is the exterior The periphery of the metal terminal 154 including the sandwiched portion is heat sealed.

  Next, a specific description will be given of the method for specifying the insulation lowering site according to the present embodiment. In this embodiment, the insulation lowering portion specifying method is a first step of measuring the electrical resistance value between the metal foil layer 172 constituting the exterior body 170 and the metal terminal 154, and the metal foil layer 172 constituting the exterior body 170 is divided into two. A second step of forming an insulating band to insulate in one region, a third step of measuring an electrical resistance value between the two regions of the insulated metal foil layer 172 and the metal terminal 154, a base material using a first strong acid In the base material layer removing step of dissolving and removing the layer 171, the metal foil layer removing step of dissolving and removing the metal foil layer 172 using the second strong acid, and the portion where the metal foil layer 172 is not removed, The fourth step of measuring the electric resistance value between the metal foil layer 172 and the metal terminal 154 is performed at least in this order. In each of the above steps, when measuring the electrical resistance value between the metal terminal 154 and the metal foil layer 172 constituting the exterior body 170, a clip material having a sharp tip is used for the connection portion of the tester. As a result, the clip material having a sharp tip is pierced into the exterior body 170 and the connection portion of the tester can be easily connected to the metal foil layer 172.

  Next, the above steps will be described in detail. 3 (a) to 3 (c) are plan views schematically showing a lithium ion battery 151 for explaining each of the above steps, and FIG. 4 shows an insulating property in the lithium ion battery 151 in FIG. 3 (a). It is sectional drawing in AA 'which passes along the fall part x. A method for detecting the insulation lowering portion x will be described below. FIG. 3A is a plan view for explaining the first step. In the case where the insulation lowering portion x occurs at the position shown in FIG. 3A and a short circuit occurs at that portion, in the first step, between the metal foil layer 172 and the metal terminal 154 constituting the exterior body 170. By measuring the electrical resistance value, it is possible to detect the occurrence of a short circuit in the lithium ion battery 151. This is because, as shown in FIG. 4, cracks or the like occur in the heat-adhesive resin layer 175 constituting the exterior body 170 at the insulation lowering portion x, and the electrolyte inside the exterior body 170 permeates the metal foil layer 172. This is because the metal terminal 154 connected to the lithium ion battery main body 152 and the metal foil layer 172 are energized through the electrolyte.

  FIG. 3B is a plan view for explaining the second step and the third step. As shown in FIG. 3B, when it is detected in the first step that a short circuit has occurred in the lithium ion battery 151, in the second step, first, an insulating band that insulates the metal foil layer 172 into two regions. A first region 182 and a second region 183 that are insulated from each other are formed. Next, in the third step, the electrical resistance value is measured between the metal foil layer 172 and the metal terminal 154 in the insulated first region 182, and the electrical resistance is measured between the metal foil layer 172 and the metal terminal 154 in the second region 183. Measure the value. At this time, in FIG. 3B, since the insulation lowering portion x exists in the second region 183, a resistance value indicating energization between the metal foil layer 172 and the metal terminal 154 in the second region 183 is measured. A resistance value indicating insulation is measured between the metal foil layer 172 and the metal terminal 154 in the one region 182.

  This is because even when the first region 182 and the second region 183 are insulated by the insulating band 181, the metal terminal 154 and the metal foil layer 172 are energized through the electrolyte in the insulation lowering portion x. From this, it can be predicted that the insulation lowering portion x exists in the second region 183.

  FIG. 3C is a plan view for explaining the base material layer removing step and the metal foil layer removing step, and FIGS. 5 and 6 are cross sections of the lithium ion battery 151 in FIG. It is sectional drawing in -A '. As shown in FIG. 3C, when it is expected that the insulation lowering portion x exists in the second A region 183a in the second region 183, first, as shown in FIG. The base material layer 171 in the second A region 183a is dissolved and removed using the first strong acid. Thereby, the metal foil layer 172 can be exposed to the exterior of the exterior body 170. Furthermore, as shown in FIG. 6, the metal foil layer 172 in the second A region 183a is melted and removed using the second strong acid in the metal foil layer removing step. Thereby, the thermoadhesive resin layer 175 in the second A region 183a can be exposed to the outside of the exterior body 170. Therefore, it is possible to specify the insulation lowering portion x in the second A region 183a from the exterior of the exterior body 170, and to clarify the cause of the insulation lowering by visual observation.

  Further, in FIG. 3C, in the second region 183, it is predicted that the insulation lowering portion x exists in the second B region 183b, and the second layer region 183b is removed by the base material layer removing step and the metal foil layer removing step. When the base material layer 171 and the metal foil layer 172 are removed, the insulation lowering portion x does not exist in the second B region 183b, and therefore the insulating lowering portion x cannot be specified. However, in the second A region 183a from which the metal foil layer 172 has not been removed, it is possible to find and specify the insulation degradation site x by performing the base material layer removal step and the metal foil layer removal step again. is there.

  Further, in FIG. 3C, after the metal foil layer 172 in the second A region 183a is removed by the metal foil layer removing step, in the second B region 183b, between the metal foil layer 172 and the metal terminal 154 constituting the outer package 170. Even if the electrical resistance value is measured, the resistance value indicating energization is not measured. Therefore, it can be confirmed that the insulation lowering portion x does not exist in the second B region 183b that is not energized. Thereby, it can be predicted that the insulation lowering portion x exists in any of the second A regions 183a.

  Further, in FIG. 3C, it is expected that the insulation lowering portion x exists in the second B region 183b, and the base material layer 171 and the metal in the second B region 183b are obtained by the base material layer removing step and the metal foil layer removing step. When the foil layer 172 is removed, when the electrical resistance value is measured between the metal foil layer 172 constituting the exterior body 170 and the metal terminal 154 in the second A region 183a, a resistance value indicating energization is measured. For this reason, it can be predicted that the insulation lowering portion x does not exist in the second B region 183b and the insulation lowering portion x exists in the second A region 183a. Therefore, in the second B region 183b from which the metal foil layer 172 has been removed, it is possible to save the trouble of searching for the insulation lowering portion x.

  In addition, in the said insulation fall site | part identification method, the base material layer 171 has the 1st base material layer distribute | arranged to the outer layer side of the exterior body 170, and the 2nd base material layer distribute | arranged to the inner layer side of the exterior body 170 When the first base material layer is a polyethylene terephthalate film or a polyethylene naphthalate film and the second base material layer is a biaxially stretched nylon film, a notch penetrating the first base material layer is formed in the base material layer 171. By performing the notch forming step to be formed before the base material layer removing step, the first strong acid permeates from the site where the notch is formed in the base material layer removing step, and the biaxially stretched nylon constituting the second base material layer The adhesive layer that bonds the film or the polyethylene terephthalate film or the polyethylene naphthalate film and the metal foil layer can be dissolved and removed. Thereby, in the base material layer removing step, the polyethylene terephthalate film or the polyethylene naphthalate film can be easily removed from the outer package 170 without dissolving the polyethylene terephthalate film or the polyethylene naphthalate film.

  Moreover, in the said insulation fall site | part identification method, by using hydrofluoric acid for the 1st strong acid which melt | dissolves and removes the base material layer 171, the base material layer 171 is comprised by resin with strong chemical resistance, such as a polyamide-type resin. Even if it is, it can be dissolved and removed.

  Moreover, in the said insulation fall site | part identification method, even if the metal foil layer 172 is comprised with aluminum, it can melt | dissolve and remove by using a hydrochloric acid solution for the 2nd strong acid which melt | dissolves and removes the metal foil layer 172. At this time, since the hydrochloric acid solution does not dissolve the heat-adhesive resin layer 175, it can be suitably used.

  As described above, by performing the above-described steps, it is possible to easily identify the insulation lowering portion x existing in the lithium ion battery 151 and to elucidate the cause of the insulation lowering in detail. In addition, the insulation fall site | part of this embodiment can also specify an insulation fall site | part further easily by performing each said process in multiple times, or combining each process.

  In addition to the above method, it is possible to specify the insulation lowering portion x using a plating method. FIG. 7 is a cross-sectional view schematically showing an apparatus for specifying an insulation lowering site by plating, and FIG. 8 is a cross-sectional view taken along line A-A ′ of the lithium ion battery 151 shown in FIG. 7. The method of specifying the insulation lowering site using the plating method corresponds to the “fifth step” described in the present invention. As shown in FIG. 8, first, the metal foil constituting the outer package 170 of the lithium ion battery 151 is used. The layer 172 and the base material layer 171 are removed by the base material layer removal step and the metal foil layer removal step, so that the exterior body 170 is configured only by the heat adhesive resin layer 175. At this time, the lithium ion battery main body 152 containing the electrolyte is hermetically housed only by the heat-adhesive resin layer 175, but the exterior body 170 inside and the exterior body 170 outside through the insulation lowering portion x such as a crack or a pinhole. Assumes that

  Next, as shown in FIG. 7, the lithium ion battery 151 is immersed in the plating solution 111 so that the metal terminal 154 protruding outside the exterior body 170 is not immersed in the plating solution 111, and the cathode terminal 112 is connected to the lithium ion battery 151. Connected to the negative metal terminal 154, the anode plate 113 is immersed in the plating solution 111, and a direct current is passed between the cathode terminal 112 and the anode plate 113.

  At this time, the metal terminal 154 connected to the cathode terminal 112 is electrically connected to the electrolyte filled in the exterior body 170, and the electrolyte functions as a cathode plate. Thereby, in the plating solution, the plating solution 111 permeates from the outside of the outer package 170 to the electrolyte filled in the outer package 170 through the insulation lowering portion x (see FIG. 8). When a direct current is passed between the cathode terminal 112 and the anode plate 113, the metal is deposited from the plating solution that has penetrated to the electrolyte surface, and a metal deposit is formed in the inside x of the lowered insulating property. Therefore, if the heat-adhesive resin layer 175 is made of a permeable resin, it is easy to cause a decrease in insulation such as cracks or pinholes by visually observing the shape of the formed metal deposit from the outside of the exterior body 170. Can be clarified. In addition, when the metal deposit is not formed by the above plating method in the region where the metal foil layer 172 is removed, there is an insulating degradation site x such as a crack or a pinhole leading from the inside of the exterior body to the metal foil layer in the region. It can be predicted.

  Further, the lithium ion battery 151 immersed in the plating solution 111 is not necessarily limited to the one in which the metal foil layer 172 and the base material layer 171 constituting the exterior body 170 are removed over the entire region. By the first step to the fourth step described in the above, the metal foil layer 172 and the base material layer 171 are removed only in the region where the insulation lowering portion x is expected to exist, and the inside of the insulation lowering portion x is formed by the plating method. A metal precipitate can be formed to specify the insulation lowering portion.

  In addition, the said method shows an example of the plating method, It is not limited to this. For example, a plating solution containing a metal salt is used as the plating solution 111, and an anode terminal can be used instead of the cathode terminal 112 and a cathode plate can be used instead of the anode plate 113 depending on the metal deposit to be deposited. . At this time, the anode terminal may be connected to the metal terminal 154 of the positive electrode of the lithium ion battery 151. Moreover, the metal salt used should just be a metal salt which can form a metal deposit by an electroplating method, and is not restrict | limited in particular. Specific metal salts include halides, acid salts, cyanides, etc. of various metals, among which nickel sulfate, nickel chloride, nickel hypophosphite, cobalt sulfate, cobalt chloride, copper sulfate, cyanide. Potassium halide is suitable, but considering the ease of visual confirmation, it is preferable that the metal precipitate exhibits a color different from the silver-white color of aluminum, particularly copper sulfate in which the metal precipitate is red. preferable. Note that the composition, temperature and pH (hydrogen ion concentration), treatment time, etc. of the solution in the electroplating method are not particularly limited, and are appropriately adjusted according to the method used, the metal salt, and the like.

  In addition, an electroless plating method can be employed instead of the electroplating method, and a heat-adhesive resin layer can be obtained by immersing the lithium ion battery 151 in a plating bath or by spraying instead of the plating solution. A method of supplying to the outer surface side of 175 can also be suitably used.

DESCRIPTION OF SYMBOLS 111 Plating solution 112 Cathode terminal 113 Anode plate 151,251 Lithium ion battery 152,252 Lithium ion battery main body 154,254 Metal terminal 170,270 Exterior body 170a, 270a Heat seal part (outer body peripheral part)
171 and 271 Base material layer 172 and 272 Metal foil layer 175 and 275 Thermal adhesive resin layer 181 Insulation band 182 First region 183 Second region 183a Second A region 183b Second B region

Claims (8)

Inside the exterior body configured by laminating at least a base material layer, a metal foil layer, and a thermal adhesive resin layer,
An electrochemical cell body comprising a positive electrode comprising a positive electrode active material and a positive electrode current collector, a negative electrode comprising a negative electrode active material and a negative electrode current collector, and an electrolyte filled between the positive electrode and the negative electrode,
A method for identifying an insulation lowering part of an electrochemical cell configured to be sealed and housed so that a tip of a metal terminal connected to each of the positive electrode and the negative electrode protrudes to the outside,
In the vicinity of the site where it is expected that there is a cause of the insulation deterioration in the exterior body,
A base material layer removing step of dissolving and removing the base material layer using a first strong acid;
After the base layer removing step, and the metal foil layer removing step of removing dissolved the metal foil layer using a second strong, only including, after the metal foil layer removing step, exposed to the exterior body external A method for identifying an insulating degradation site, wherein the insulation degradation site generated in the thermal adhesive resin layer is identified by viewing the thermal adhesive resin layer .   The insulation lowering according to claim 1, further comprising a first step of measuring an electric resistance value between the metal foil layer constituting the exterior body and the metal terminal before the base material layer removing step. Site identification method. After the occurrence of a short circuit is confirmed in the first step, and before the base material layer removing step,
A second step of forming an insulating band for insulating the metal foil layer into two regions;
After the second step, the method includes a third step of measuring electrical resistance values between the two regions of the insulated metal foil layer and the metal terminals,
The insulating band is obtained by dissolving and removing the base material layer constituting the exterior body using the first strong acid, and then dissolving and removing the metal foil layer constituting the exterior body using the second strong acid. 3. The method for identifying an insulation-decreasing portion according to claim 2 , wherein the method is performed.   After the metal foil layer removing step, the method includes a fourth step of measuring an electrical resistance value between the metal foil layer constituting the exterior body and the metal terminal in a portion where the metal foil layer is not removed. The insulation-decreasing site | part identification method of any one of Claims 1-3 characterized by the above-mentioned. After the metal foil layer removal step, at the site where the metal foil layer is removed,
5. The insulation lowering site specifying method according to claim 1, further comprising a fifth step of forming a metal deposit using a plating method. The base material layer has a first base material layer disposed on the outer layer side of the exterior body and a second base material layer disposed on the inner layer side of the exterior body,
When the first base material layer is a polyethylene terephthalate film or a polyethylene naphthalate film, and the second base material layer is a biaxially stretched nylon film,
6. The method according to claim 1, further comprising a notch forming step of forming a notch penetrating the first base material layer in the base material layer before the base material layer removing step. Method for identifying the lowered insulating property of the material.   The insulation lowering site specifying method according to any one of claims 1 to 6, wherein the first strong acid is hydrofluoric acid.   The method for identifying an insulating decrease site according to any one of claims 1 to 7, wherein the second strong acid is a hydrochloric acid solution.

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