JP2009158266A - Evaluation method of electrochemical element and evaluation device of electrochemical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an evaluation method of an electrochemical element for reproducing a pseudo short-circuit by metal powder, and quantitatively evaluating durability of an insulation layer laminated on an electrode for the electrochemical element. <P>SOLUTION: The evaluation method of the electrochemical element includes a needle insertion process in which a load is impressed on a needle 4 equipped with a tip part 4a made of a conductive member, the tip part 4a is inserted into the insulation layer 12 from the surface of the insulation layer 12 laminated on the electrode 10 for the electrochemical element, and is made to reach the electrode 10 for the electrochemical element. In the needle insertion process, the load as well as an electric resistance between the tip part 4a and the electrode 10 for the electrochemical element is measured at time lapses. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electrochemical element evaluation method and an electrochemical element evaluation apparatus.

  In recent years, at the time of manufacturing a lithium secondary battery which is a kind of electrochemical element, metal powder mixed in the battery causes a short circuit between the electrodes, and the short circuit frequently causes an accident in which the battery generates heat and ignites.

  As a measure for preventing such an accident, Patent Document 1 below discloses that an electrode layer is coated with an insulating layer made of a porous material. By coating an insulating layer on the electrode surface, it is possible to suppress the occurrence of a short circuit and to reduce the amount of heat generated at the time of the short circuit.

  Further, in Patent Documents 2 to 5 below, in order to verify the relationship between the shape, material, thickness, or manufacturing method of the above-described insulating layer and the amount of heat generated by the battery at the time of short circuit, a nail is formed on the side of the battery after charging. A nail penetration test for measuring the temperature of a battery that has generated heat is shown.

Japanese Patent Laid-Open No. 7-220759 JP 2005-174792 A JP 2005-285605 A JP 2006-164596 A JP 2007-27100 A

  However, the short circuit and the heat generation of the battery reproduced by the nail penetration test shown in the above Patent Documents 2 to 5 and the actual short circuit and the heat generation generated by mixing metal powder into the battery differ in the generation mechanism. It is a phenomenon. In an actual battery, metal powder mixed in the battery during the production of the battery repeats deposition and dissolution on the electrode by charging and discharging of the battery. It is considered that the deposited metal powder gradually grows and breaks through the insulating layer, causing a short circuit between the positive electrode and the negative electrode. In addition, it is conceivable that the metal powder breaks through the insulating layer and the separator due to an external impact and the expansion and contraction of the electrode accompanying charging / discharging of the battery. These complex phenomena could not be simulated with a simple nail penetration test.

  Japan Electronics and Information Technology Industries Association (hereinafter referred to as “JEITA”) received a report from the Ministry of Economy, Trade and Industry working group, provided guidelines for simulating short-circuiting by metal powder, and replaced the above-mentioned nail penetration test. An evaluation method was proposed. In the evaluation method of JEITA, after disassembling the assembled battery once, metal powder is mixed into the electrode part of the battery, and after this is stored again in the battery can, pressure is applied to the battery to check for short circuits. With this evaluation method, it is possible to simulate a short circuit due to the mixing of metal powder into the battery.

  However, according to the evaluation method of JEITA, when the electrode part is stored again in the battery can after disassembling the battery, there is a possibility that a cause of a short circuit other than the mixing of the metal powder may occur. In addition, in the evaluation method of JEITA, there is a possibility that reproducibility cannot be obtained with respect to the evaluation result of the influence of the metal powder on the short circuit.

  Further, in the conventional nail penetration test and JEITA evaluation method, it is difficult to quantitatively evaluate the durability of the insulating layer for preventing a short circuit.

  The present invention has been made in view of the above-described problems of the prior art, can simulate a short circuit caused by metal powder, and quantitatively evaluate the durability of an insulating layer laminated on an electrode for an electrochemical element. It is an object of the present invention to provide an electrochemical element evaluation method and an electrochemical element evaluation apparatus that can be evaluated in an easy manner.

  In order to achieve the above object, the electrochemical element evaluation method according to the present invention applies a load to a needle having a tip made of a conductive member, and the tip is insulated by being stacked on the electrode for the electrochemical element. A needle insertion step of inserting from the surface of the layer to the inside of the insulating layer and reaching the electrode for an electrochemical element, and in the needle insertion step, a load and an electrical resistance between the tip and the electrode for the electrochemical element; Is measured over time.

  When the tip of the needle is inserted into the insulating layer and reaches the electrode for the electrochemical element, that is, when the tip pierces the insulating layer, the tip and the electrode for the electrochemical element pass through the insulating layer. In this case, the electrical resistance between the tip and the electrochemical element electrode is discontinuously (rapidly) reduced. In the present invention, the electrical resistance between the tip and the electrochemical element electrode is measured by measuring the load applied to the needle and the electrical resistance between the tip and the electrochemical element electrode over time. It is possible to detect the load at the time when the voltage drops discontinuously (rapidly). In other words, when the tip portion breaks through the insulating layer and short-circuits with the electrode for an electrochemical element, the load acting on the insulating layer through the tip portion of the needle (breaking load of the insulating layer) can be directly measured. . Thus, in the present invention, the durability of the insulating layer can be quantitatively evaluated.

  In the present invention, if the tip of the needle is regarded as metal powder mixed in the battery or metal powder grown in the battery, the tip penetrates the insulating layer and reaches the electrode for the electrochemical element. The state can be regarded as a short circuit caused by the metal powder penetrating the insulating layer. Therefore, according to the present invention, a short circuit that occurs due to the mixing of metal powder into the battery can be simulated.

  Further, in the present invention, as in the evaluation method of JEITA, it is not necessary to perform a complicated operation of disassembling the battery and taking out the electrode part from the battery can and then storing the electrode part in the battery can again. In this case, the possibility of causing a short circuit is small except that the insulating layer is pierced by the tip of the needle. Therefore, in the present invention, the reproducibility and reliability of the measurement result of the breaking load is improved as compared with the conventional evaluation method.

  In the electrochemical element evaluation method according to the present invention, the electrochemical element electrode includes an active material-containing layer and a current collector laminated on the active material-containing layer, and the insulating layer is laminated with the current collector. It is preferable that the active material-containing layer is laminated on the side opposite to the formed side.

  As a result, the laminated structure of the electrode for the electrochemical element and the insulating layer is made the same structure as the electrode and the insulating layer mounted in the battery, so that the destructive load of the insulating layer mounted in the battery is reduced. It can be evaluated in a pseudo manner.

  In the electrochemical element evaluation method according to the present invention, the insulating layer may be a protective layer for protecting the electrochemical element electrode, or may be a separator. Alternatively, the insulating layer may include both a protective layer and a separator laminated on the protective layer.

  Thereby, the breaking load of each protective layer or separator can be measured directly.

  The electrochemical device evaluation apparatus according to the present invention is arranged so that the tip portion faces the surface of the insulating layer laminated on the electrode for the electrochemical device, the tip portion is made of a conductive member, and the needle is loaded. , A load applying means for inserting the tip portion from the surface of the insulating layer into the insulating layer and reaching the electrode for the electrochemical device, a load measuring means for measuring the load over time, the tip portion and the electrochemical And a resistance measuring means for measuring the electrical resistance with the element electrode over time.

  By using the electrochemical device evaluation apparatus according to the present invention, the electrochemical element evaluation method according to the present invention can be easily implemented.

  In the electrochemical device evaluation apparatus according to the present invention, it is preferable that the load measuring means measures a load in a direction substantially perpendicular or substantially parallel to the surface of the insulating layer among the loads applied to the needle. Thereby, the breaking load of the insulating layer in a direction substantially perpendicular or substantially parallel to the surface of the insulating layer can be measured. In addition, the load measuring means may have a function of measuring a load in an oblique direction with respect to the surface of the insulating layer among the loads applied to the needle.

  In the electrochemical device evaluation apparatus according to the present invention, it is preferable that the curvature R of the tip portion is 1 μm to 5 mm.

  By appropriately setting the curvature R of the tip within the above-mentioned preferred range, the particle size of the metal powder that causes a short circuit can be reproduced in a pseudo manner. Therefore, in this invention, the relationship between the particle size of a metal powder and the destruction load of an insulating layer can be evaluated. For example, when the particle diameter of the actual metal powder is on the μm scale, the durability of the insulating layer can be more accurately evaluated by setting the curvature R of the tip portion to the μm scale.

  In the electrochemical element evaluation method and evaluation apparatus according to the present invention, it is preferable that a portion other than the tip portion of the surface of the needle is an insulator. Moreover, in the electrochemical element evaluation method and evaluation apparatus according to the present invention, it is preferable that the length of the tip portion in the longitudinal direction is 1 to 20 μm.

  Thus, only the tip of the needle surface is locally made of a conductive member, or the length of the tip in the longitudinal direction is limited to the above range, for example, the insulating layer and electrochemical When evaluating a multilayer electrode having a structure in which a plurality of device electrodes are alternately stacked, the tip is electrically connected to only a single insulating layer or a single electrochemical device electrode. Can do. Therefore, the breaking load of each of the laminated insulating layers can be measured individually. In other words, since any one of the plurality of stacked electrochemical element electrodes and the tip can be individually short-circuited, the short-circuit state at each depth position (position in the electrode stacking direction) can be determined. I can know.

  According to the present invention, a short circuit caused by metal powder can be reproduced in a pseudo manner, and an electrochemical element evaluation method capable of quantitatively evaluating the durability of an insulating layer laminated on an electrode for an electrochemical element, And an electrochemical device evaluation apparatus.

  Hereinafter, a lithium ion secondary battery evaluation apparatus and a lithium ion secondary battery evaluation method using the evaluation apparatus according to a preferred embodiment of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted. Further, the positional relationship such as up, down, left and right is based on the positional relationship shown in the drawings unless otherwise specified. Further, the dimensional ratios and positional relationships in the drawings are not limited to those illustrated.

(Electrode for lithium ion secondary battery)
The evaluation apparatus for a lithium ion secondary battery according to this embodiment uses a lithium ion secondary battery electrode (hereinafter referred to as electrode 10), which is a kind of electrode for an electrochemical element, as a measurement object.

  As shown in FIG. 1, the electrode 10 includes an active material containing layer 14 and a current collector 16 laminated on the active material containing layer 14, and an insulating layer 12 is provided on the active material containing layer 14 side of the electrode 10. Are stacked. Thereby, the electrode 10 which has the same structure as the electrode mounted in the battery can be evaluated. The electrode 10 may be an anode electrode or a cathode electrode.

When the electrode 10 is an anode electrode, the active material-containing layer 14 is a layer containing a negative electrode active material (anode active material), a conductive additive, a binder, and the like. The anode active material includes insertion and extraction of lithium ions, desorption and insertion (intercalation) of lithium ions, or doping and dedoping of lithium ions and counter anions (for example, PF ₆ ⁻ ) of the lithium ions. A known anode active material can be used without particular limitation as long as it can proceed reversibly. As such an active material, for example, natural graphite, artificial graphite, non-graphitizable carbon, graphitizable carbon, low-temperature calcined carbon and other carbon materials, lithium such as Al, Si, Sn, Si, etc. Examples thereof include amorphous metals such as SiO, SiO _x , SiO ₂ and SnO ₂ , lithium titanate (Li ₄ Ti ₅ O ₁₂ ), and TiO ₂ . Among these, a carbon material is preferable, and a carbon material having an interlayer distance d ₀₀₂ of 0.335 to 0.338 nm and a crystallite size Lc ₀₀₂ of 30 to 120 nm is more preferable. Examples of the carbon material satisfying such conditions include artificial graphite, MCF (mesocarbon fiber), MCMB (mesocarbon microbead), and the like. The interlayer distance d ₀₀₂ and the crystallite size Lc ₀₀₂ can be obtained by an X-ray diffraction method.

When the electrode 10 is a cathode electrode, the active material containing layer 14 is a layer containing a positive electrode active material (cathode active material), a conductive additive, a binder, and the like. Cathode active materials include insertion and extraction of lithium ions, desorption and insertion (intercalation) of lithium ions, or doping and dedoping of lithium ions and counter anions of the lithium ions (for example, PF ₆ ⁻ ). If it can be made to advance reversibly, it will not specifically limit, A well-known electrode active material can be used. For example, lithium cobaltate (LiCoO ₂ ), lithium nickelate (LiNiO ₂ ), lithium manganese spinel (LiMn ₂ O ₄ ), and the general formula: LiNi _x Co _y Mn _z M _a O ₂ (x + y + z + a = 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1, 0 ≦ a ≦ 1, M is one or more elements selected from Al, Mg, Nb, Ti, Cu, Zn, and Cr) Composite metal oxide, lithium vanadium compound (LiV ₂ O ₅ ), olivine-type LiMPO ₄ (where M is one or more elements selected from Co, Ni, Mn, Fe, Mg, Nb, Ti, Al, Zr) Or a composite metal oxide such as lithium titanate (Li ₄ Ti ₅ O ₁₂ ).

  As the current collector 16, a current collector used in a known electrochemical device can be used, and examples thereof include metal foils such as copper, aluminum, and nickel.

  The insulating layer 12 may be a protective layer that protects the electrode 10 or may be a separator. Thereby, it is possible to directly measure the breaking load of each of the protective layer or the separator laminated on the electrode 10. Or the insulating layer 12 may be comprised from two layers of the separator laminated | stacked on the protective layer and the protective layer.

  The protective layer is a layer containing a resin binder and a ceramic material. Examples of the ceramic material include oxide ceramics such as alumina, silica, titania, zirconia, zinc oxide, magnesia, and mullite, nitride ceramics such as silicon nitride and titanium nitride, silicon carbide, calcium carbonate, talc, and kaolin. Ceramics or a composite compound thereof can be used. These materials may be used alone or in combination.

  The separator is a layer disposed between the cathode electrode and the cathode electrode, and is formed of an electrically insulating porous body. As the electrically insulating porous body, for example, at least 1 selected from the group consisting of a monolayer or laminate of a film made of polyethylene, polypropylene or polyolefin, a stretched film of a mixture of resins, or cellulose, polyester and polypropylene is used. Examples thereof include a fiber nonwoven fabric made of various constituent materials.

  In addition, the thickness of the active material content layer 14 is about 20-200 micrometers. The thickness of the current collector 16 is about 6 to 25 μm. The thickness of the insulating layer 12 is about 0.05 to 10 μm.

(Evaluation apparatus and evaluation method for lithium ion secondary battery)
As shown in FIG. 1, the evaluation apparatus 2 for a lithium ion secondary battery according to the present embodiment is a needle 4, a vertical moving member 7 and a horizontal moving member 9 that are load applying means, and a load measuring means. A load cell 6 and a resistance measuring device 8 as resistance measuring means are provided. The electrode 10 which is a measurement object is placed on the table 3. The electrode 10 on the table 3 may be fixed by a fixing means (not shown). The surface of the table 3 on which the electrode 10 is placed may be a flat surface or a curved surface.

  The vertical movement member 7 is connected to the column 5 fixed to the table 3, and has a function of moving freely in the vertical direction (longitudinal direction of the column 5). The horizontal movement member 9 connected to the vertical movement member 7 has a function of freely moving in the horizontal direction (longitudinal direction of the vertical movement member 7). The load cell 6 is fixed to the horizontal moving member 9.

  The needle 4 is fixed to the load cell 6 so that the tip end portion 4 a faces the surface of the insulating layer 12. The tip 4a of the needle 4 is made of a conductive member such as metal. The needle 4 can be moved in the vertical direction by the vertical movement member 7 and can be moved in the horizontal direction by the horizontal movement member 9. The diameter of the cross section perpendicular to the longitudinal direction of the needle 4 is about 10 to 5000 μm.

  The vertically moving member 7 serving as a load applying means applies a load perpendicular to the surface of the insulating layer 12 to the needle 4, inserts the tip end portion 4 a from the surface of the insulating layer 12 into the insulating layer 12, and It has a function to reach 10. The load cell 6 has a function of measuring the load applied to the needle 4 by the vertical movement member 7 over time. If such an evaluation apparatus 10 is used, a so-called piercing test can be performed. The horizontal moving member 9 applies a load parallel to the surface of the insulating layer 12 stacked on the electrode 10 to the needle 4, and the load cell 6 applies a load applied to the needle 4 by the horizontal moving member 9. It also has a function of measuring over time. If such an evaluation apparatus 10 is used, a so-called scratch test can be performed.

  The resistance measuring device 8 is electrically connected to the tip portion 4a, and is electrically connected to the electrode 10 in either the active material-containing layer 14 or the current collector 16, and the tip portion 4a and the electrode 10 are electrically connected. It has a function to measure the electrical resistance between the two over time. In this embodiment, the resistance measuring device 8 is electrically connected to the current collector 16.

  By using the evaluation apparatus 2 described above, the evaluation method for a lithium ion secondary battery according to this embodiment shown below can be easily implemented.

  In the evaluation method of the lithium ion secondary battery according to the present embodiment, first, the tip part 4a of the needle 4 is brought into contact with the surface of the insulating layer 12 by operating the vertical movement member 7 and the horizontal movement member 9. Hold. Next, in the needle insertion step, by continuously applying a load to the needle 4 by the up-and-down moving member 7 which is a load applying means, the tip 4a of the needle 4 is moved from the surface of the insulating layer 12 as shown in FIG. Inserted into the insulating layer 12, and further, the tip 4a reaches the active material-containing layer 14 as shown in FIG. In this needle insertion process, while the load is continuously applied to the needle 4 by the up-and-down moving member 7, the load is measured over time by the load cell 6, and the electrical resistance between the tip 4a and the electrode 10 is also measured over time. taking measurement.

  As shown in FIG. 3, when the tip 4 a reaches the active material containing layer 14, that is, when the tip 4 a breaks through the insulating layer 16, the tip 4 a and the active material containing layer 14 are connected to the insulating layer 16. Therefore, the electrical resistance between the tip 4a and the electrode 10 decreases discontinuously. In the needle insertion step, as described above, the load applied to the needle 4 by the vertical movement member 7 and the electrical resistance between the tip portion 4a and the electrode 10 are measured over time. The load at the time when the electrical resistance between 4a and the electrode 10 decreases discontinuously can be detected. In other words, when the tip 4a breaks through the insulating layer 12 and short-circuits with the electrode 10, the load (the breaking load of the insulating layer 12) exerted on the insulating layer 12 by the vertically moving member 7 via the needle 4 is directly measured. can do. Thus, in this embodiment, it is possible to quantitatively evaluate the durability of the insulating layer 12 serving as a battery safety determination material.

  In this embodiment, if the tip 4a of the needle 4 is regarded as metal powder mixed in the battery or metal powder grown in the battery, the tip 4a penetrates through the insulating layer 12 and the active material containing layer. The state of reaching 14 can be regarded as a short circuit caused by the metal powder penetrating the insulating layer 12. Therefore, in this embodiment, the short circuit which generate | occur | produces by mixing of the metal powder into the inside of a battery is reproducible.

  Further, in this embodiment, as in the evaluation method of JEITA, it is not necessary to perform a complicated operation of disassembling the battery and taking out the electrode part from the battery can and then storing the electrode part in the battery can again. In this case, in addition to the insulating layer 12 being pierced by the tip 4a of the needle 4, the possibility of a short circuit is small. Therefore, in this embodiment, reproducibility and reliability are improved in the measurement result of the breaking load of the insulating layer 12 as compared with the conventional evaluation method.

  In the present embodiment, the relationship between the material or thickness of the insulating layer 12 and the breaking load of the insulating layer 12 is evaluated by evaluating each of the electrodes 10 on which the insulating layers 12 having different materials or thicknesses are stacked. Can do.

  In the evaluation apparatus 2, it is preferable that the load cell 6 measures a load in a direction substantially perpendicular or substantially parallel to the surface of the insulating layer 12 among the loads applied to the needle 4. Thereby, not only the breaking load of the insulating layer 12 when a load substantially perpendicular to the surface of the insulating layer 12 acts can be measured, but also the case where a load substantially parallel to the surface of the insulating layer 12 acts. The breaking load of the insulating layer 12 can also be measured.

  It is preferable that the curvature R of the front-end | tip part 4a is 1 micrometer-5 mm. By appropriately setting the curvature R of the tip portion 4a within 1 μm to 5 mm, the particle size of the metal powder that causes a short circuit can be simulated. Therefore, the relationship between the particle size of the metal powder and the breaking load of the insulating layer 12 can be evaluated. For example, when the particle diameter of the actual metal powder is on the μm scale, the durability of the insulating layer 12 can be more accurately evaluated by setting the curvature R of the tip portion to the μm scale. Further, by appropriately setting the curvature R of the tip portion 4a within 1 μm to 5 mm, the contact area between the tip portion 4a and the insulating layer 12 and the pressure exerted by the tip portion 4a on the insulating layer 12 are adjusted within a predetermined range. Therefore, it is possible to evaluate the range of pressure that the insulating layer 12 can tolerate when the metal powder in the battery is mixed.

  As shown in FIGS. 2 and 3, the portion of the surface of the needle 4 other than the tip portion 4 a is preferably an insulator. Moreover, it is preferable that the length L of the front-end | tip part 4a in the longitudinal direction is 1-20 micrometers (refer FIG. 1).

  Thus, only the tip 4a of the surface of the needle 4 is made of a conductive member, or the length L in the longitudinal direction of the tip 4a is limited to the above range, for example, the insulating layer 12 When evaluating a multilayer electrode having a structure in which a plurality of electrodes and electrodes 10 are alternately stacked, the tip 4a is electrically connected to only a single insulating layer 12 or only a single electrode 10. Can do. Therefore, the breaking load of the laminated insulating layers 12 can be individually measured. In other words, since any one of the stacked electrodes 10 can be individually short-circuited to the tip portion 4a, it is possible to know the short-circuit state for each depth position (position in the stacking direction). .

  In the needle insertion step, the speed of the tip 4a when the tip 4a of the needle 4 is inserted from the surface of the insulating layer 12 into the insulating layer 12 and reaches the active material-containing layer 14 is 0.1-1 mm / It is preferably about min. By increasing the speed of the tip 4a, it is possible to simulate a short circuit that occurs when an external impact is applied to the battery. Moreover, the short circuit caused by the metal powder gradually grown in the battery can be reproduced by reducing the speed of the tip 4a.

  As mentioned above, although one suitable embodiment of the electrochemical device of this invention was described in detail, this invention is not limited to the said embodiment. For example, in the description of the above embodiment, the case where the evaluation target is a lithium ion secondary battery has been mainly described. However, the evaluation target is not limited to the lithium ion secondary battery, such as a metal lithium secondary battery. Secondary batteries other than lithium ion secondary batteries, electrochemical capacitors such as lithium capacitors, and the like may be used. Moreover, the evaluation apparatus 10 may be provided with either the up-down direction moving member 7 or the horizontal direction moving member 9 independently as a load application means.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example, this invention is not limited to a following example.

Using the evaluation apparatus 2 for a lithium ion secondary battery shown in FIG. 1, the puncture strength (unit: gf (= 9.80665 × 10 ⁻³ kg · m / s ^{2) of} samples 1 to 10 as shown below. )) Was measured. In addition, the diameter of the cross section perpendicular | vertical to the longitudinal direction of the needle | hook 4 with which the evaluation apparatus 2 is provided was 500 micrometers. The length L in the longitudinal direction of the tip portion 4a was 10 μm, and the curvature R of the tip portion 4a was 10 μm. Hereinafter, the measurement of the piercing strength will be described using the sample 1 as an example.

(Sample 1)
As shown in FIGS. 1 to 3, the electrode for a lithium ion secondary battery of Sample 1 is an electrode 10 having two layers of an active material-containing layer 14 and a current collector 16 laminated on the active material-containing layer 14. Was used. An insulating layer 12 was laminated on the active material containing layer 14 side of the electrode 10. The active material-containing layer 14 was made of carbon, which is an active material for a negative electrode, the current collector 16 was made of copper foil, and the insulating layer 12 was made of alumina and a resin binder. The thickness of the active material containing layer 14 was 80 μm, the thickness of the current collector 16 was 15 μm, and the thickness of the insulating layer 12 was 7 μm.

  In the evaluation of the sample 1, first, the electrode 10 is fixed on the plane of the table 3 by fixing means (not shown) provided in the evaluation device 2, and then the tip 4a of the needle 4 is brought into contact with the surface of the insulating layer 12. Held. Next, in the needle insertion step, the tip 4a of the needle 4 is attached to the insulating layer by continuing to apply a load in a direction perpendicular to the surface of the insulating layer 12 to the needle 4 by the vertical movement member 7 which is a load applying means. The tip 12a was inserted vertically from the surface of 12 into the insulating layer 12 to reach the active material-containing layer 14. In the needle insertion step, while the load is continuously applied to the needle 4 by the up-and-down moving member 7, the load applied to the needle 4 is measured with the load cell 6 over time, and the electricity between the tip 4a and the electrode 10 is measured. Resistance was also measured over time. From the measurement results of the load and electrical resistance over time, the load at the time when the electrical resistance between the tip 4a and the electrode 10 was reduced to 1 kΩ or less was detected. That is, the load (the piercing strength) acting on the insulating layer 12 was detected when the tip 4a broke through the insulating layer 12 and shorted with the electrode 10. The results are shown in Table 1.

  In the needle insertion step, the speed of the tip 4a when the tip 4a of the needle 4 is inserted from the surface of the insulating layer 12 into the insulating layer 12 and reaches the active material-containing layer 14 is 0.5 mm / It was set to min. Further, as the load cell 6, a load cell having a maximum measured value of 5N was used.

(Samples 2 to 10)
Samples 2 to 10 were evaluated in the same manner as Sample 1 except that the thickness of the insulating layer 12 was set to the value shown in Table 1. The results are shown in Table 1. Moreover, the thickness of the insulating layer of Samples 1-10 and the piercing strength were plotted in FIG. FIG. 5 shows a graph in which the electrical resistance (kΩ) between the tip 4a and the electrode 10 measured at each time point (unit: second) of the needle insertion process for the sample 1 is plotted.

  From the measurement results shown in Table 1 and FIG. 4, it was confirmed that there was a proportional relationship between the thickness of the insulating layer and the piercing strength. Further, as shown in FIG. 5, it was confirmed that in the needle insertion process, the electrical resistance between the tip portion 4 a and the electrode 10 rapidly decreased.

It is a model perspective view which shows suitable one Embodiment of the evaluation apparatus of the electrochemical element which concerns on this invention. It is a schematic diagram showing a preferred embodiment of a method for evaluating an electrochemical element according to the present invention, an electrode, an insulating layer stacked on the electrode, and a needle inserted into the insulating layer, the length of the needle It is a schematic cross section at the time of cut | disconnecting in parallel with respect to a direction. It is a schematic diagram showing a preferred embodiment of an electrochemical element evaluation method according to the present invention, and comprises an electrode, an insulating layer laminated on the electrode, and a needle whose tip is in contact with the electrode in the longitudinal direction of the needle It is a schematic cross section at the time of cut | disconnecting in parallel with respect. It is a graph which shows the thickness and puncture strength of the insulating layer of samples 1-10. 4 is a graph plotting electrical resistance between a tip portion 4a and an electrode 10 measured at each time point in a needle insertion process for a sample 1. FIG.

Explanation of symbols

  2 ... Electrochemical element evaluation apparatus, 4 ... Needle, 4a ... Tip, 6 ... Load cell (load measuring means), 7 ... Vertical movement member (load applying means), 8 ... Resistance measuring means, 9 ... horizontal moving member (load applying means), 10 ... electrochemical element electrode, 12 ... insulating layer, 14 ... active material containing layer, -Current collector.

Claims (11)

A load is applied to a needle having a distal end portion made of a conductive member, and the distal end portion is inserted into the insulating layer from the surface of the insulating layer laminated on the electrochemical element electrode, and the electrochemical element electrode With a needle insertion process to reach
The method for evaluating an electrochemical element, wherein, in the needle insertion step, the load and the electric resistance between the tip and the electrochemical element electrode are measured over time. The electrochemical element electrode includes an active material-containing layer, and a current collector laminated on the active material-containing layer,
The method for evaluating an electrochemical element according to claim 1, wherein the insulating layer is laminated on the active material-containing layer on the side opposite to the side on which the current collector is laminated.   The method for evaluating an electrochemical element according to claim 1, wherein the insulating layer is a protective layer for protecting the electrode for an electrochemical element.   The method for evaluating an electrochemical element according to claim 1, wherein the insulating layer is a separator.   The method for evaluating an electrochemical element according to any one of claims 1 to 4, wherein a portion other than the tip portion of the surface of the needle is an insulator.   The method for evaluating an electrochemical element according to any one of claims 1 to 5, wherein a length of the tip portion in a longitudinal direction is 1 to 20 µm. A tip is disposed so as to face the surface of the insulating layer laminated on the electrode for an electrochemical element, and the tip is a needle made of a conductive member;
A load applying means for applying a load to the needle, inserting the tip from the surface of the insulating layer into the insulating layer, and reaching the electrode for an electrochemical element;
Load measuring means for measuring the load over time;
Resistance measuring means for measuring the electrical resistance between the tip and the electrochemical element electrode over time;
An electrochemical element evaluation apparatus comprising:   The electrochemical device evaluation apparatus according to claim 7, wherein the load measuring unit measures a load in a direction substantially perpendicular or substantially parallel to a surface of the insulating layer among the loads applied to the needle. .   The electrochemical device evaluation apparatus according to claim 7 or 8, wherein a curvature R of the tip portion is 1 µm to 5 mm.   The evaluation device for an electrochemical element according to any one of claims 7 to 9, wherein a portion other than the tip portion of the surface of the needle is an insulator.   The evaluation device for an electrochemical element according to any one of claims 7 to 10, wherein a length of the tip portion in a longitudinal direction is 1 to 20 µm.

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