JP2019186008A - Secondary battery - Google Patents

Abstract

To provide a secondary battery capable of suppressing a temperature rise amount of the secondary battery, even in short circuit mode where a nail is penetrated into a secondary battery from the outside, such as a nail penetration test.SOLUTION: There is provided a secondary battery in which at least one of a positive electrode current collector and a negative electrode current collector contains an amorphous alloy. In the secondary battery, a surface coat of the amorphous alloy is dense, and the thickness of the surface coat is relatively uniform, so that, even in short circuit mode such as a nail penetration test, contact resistance between the positive electrode current collector and the negative electrode current collector does not decrease excessively and a temperature rise amount can be suppressed. Further, when the positive electrode current collector contains an Fe-based amorphous alloy and the negative electrode current collector contains copper or a copper alloy, output of the secondary battery is also increased.SELECTED DRAWING: Figure 5

Description

  The present disclosure relates to a secondary battery. In particular, the present disclosure relates to a secondary battery in which an increase in temperature is suppressed even when a positive electrode current collector and a negative electrode current collector are short-circuited in a nail penetration test or the like.

  Secondary batteries that can be repeatedly used by charging are widely used from the viewpoints of economy and environmental protection. In addition, recent secondary batteries have dramatically improved performance such as energy density. Therefore, the fields in which secondary batteries are used are rapidly expanding.

  There are various types of secondary batteries. In any type of secondary battery, electricity is supplied from a positive electrode current collector and a negative electrode current collector (hereinafter, the positive electrode current collector and the negative electrode current collector may be collectively referred to as “current collector”). It is common in the point to take out.

  As the current collector of the secondary battery, aluminum may be used for the positive electrode current collector, and copper may be used for the negative electrode current collector. However, the current collector of the secondary battery may be a combination other than the materials described above, and the material of the current collector is appropriately determined depending on the type of secondary battery and / or its use.

  For example, Patent Document 1 discloses using a ferritic stainless steel foil as a positive electrode current collector of a non-aqueous electrolyte secondary battery. Further, it is disclosed that the ferritic stainless steel foil is made of Japanese Industrial Standard SUS444, its hardness is 200 Hv, and its thickness is 6-12.

JP 2003-178766 A

  The positive electrode current collector disclosed in Patent Document 1 can be made thin and can be made difficult to short-circuit. However, once the short circuit occurs, there is a problem that the temperature of the secondary battery increases.

  Therefore, in the short-circuit mode in which the nail is inserted into the secondary battery from the outside as in the nail penetration test, the resistance of the conventional positive electrode current collector is excessively reduced, and the secondary battery The present inventor has found a problem that the amount of temperature increase is high.

  The present disclosure has been made to solve the above problems, and suppresses the temperature increase of the secondary battery even in a short-circuit mode in which the nail is inserted into the secondary battery from the outside, as in the nail penetration test. An object of the present invention is to provide a secondary battery that can be used.

In order to achieve the above object, the present inventor has intensively studied and completed the secondary battery of the present disclosure. The aspect is as follows.
<1> A secondary battery in which at least one of a positive electrode current collector and a negative electrode current collector contains an amorphous alloy.
<2> The secondary battery according to <1>, wherein the positive electrode current collector includes an Fe-based amorphous alloy, and the negative electrode current collector includes copper or a copper alloy.

  According to the secondary battery of the present disclosure, since at least one of the positive electrode current collector and the negative electrode current collector contains an amorphous alloy, the positive electrode current collector and the negative electrode current collector can be used even in a short-circuit mode such as a nail penetration test. Contact resistance does not decrease excessively. As a result, according to the secondary battery of the present disclosure, it is possible to provide a secondary battery that can suppress the amount of temperature increase even in a short-circuit mode such as a nail penetration test.

FIG. 1 is a diagram schematically showing the structure of a normal metal or alloy and an amorphous alloy. FIG. 2 is a schematic view showing a longitudinal section of an all-solid lithium ion secondary battery. FIG. 3 is a schematic diagram for three-dimensionally explaining the structure of the all-solid-state lithium ion secondary battery shown in FIG. FIG. 4 is an explanatory diagram showing an outline of the nail penetration test apparatus. FIG. 5 is a graph showing the relationship between stress and contact resistance for the combinations of the positive electrode current collector and the negative electrode current collector of Examples 1-2 and Comparative Examples 1-2. FIG. 6 is a graph showing the relationship between stress and contact resistance for the combination of the positive electrode current collector and the negative electrode current collector of Example 1, Examples 3 to 4, and Comparative Examples 1 and 2. FIG. 7 is a graph showing the outputs of the secondary batteries of Example 1, Examples 3-4, and Comparative Examples 1-2.

  Hereinafter, embodiments of the secondary battery of the present disclosure will be described in detail. In addition, embodiment shown below does not limit the secondary battery of this indication.

  In a secondary battery, during normal use, the positive electrode current collector is in contact with the positive electrode active material, and the negative electrode current collector is in contact with the negative electrode active material. On the other hand, when a metal object such as a nail is inserted into the secondary battery as in the nail penetration test, the positive electrode current collector and / or the negative electrode current collector is wound inside the secondary battery, and the positive electrode current collector The body and the negative electrode current collector contact (short circuit). And since Joule heat generate | occur | produces by this contact, the temperature of a secondary battery rises.

  As described above, in the secondary battery, aluminum may be used for the positive electrode current collector and copper may be used for the negative electrode current collector. On the other hand, even if stainless steel having higher resistance than aluminum and copper is used, the amount of Joule heat generated during the nail penetration test cannot be suppressed. The performance sometimes deteriorated.

  However, when an amorphous alloy is used for at least one of the positive electrode current collector and the negative electrode current collector, there is little degradation in performance during normal use of the secondary battery, and there is almost no problem in practical use. The present inventor has found that heat can be remarkably suppressed.

  Although not bound by theory, it is considered that this reason can be explained as follows using FIG.

  FIG. 1 is a diagram schematically showing the structure of a normal metal or alloy and an amorphous alloy. In FIG. 1, (a) shows the structure of a normal metal or alloy, and (b) shows the structure of an amorphous alloy.

  Both ordinary metals or alloys and amorphous alloys have a surface coating 200 of oxide or the like. Unlike the high resistance film artificially applied, the surface film 200 has a certain degree of conductivity. Due to this conductivity, electrons can move inside the surface coating 200 during normal use of the secondary battery.

  A normal metal or alloy is a collection of crystal grains. Therefore, as shown in FIG. 1A, the surface coating 200 of a normal metal or alloy has an intersection 225 with the crystal grain boundary 220. At the intersection 225, the thickness of the surface coating 200 is locally reduced.

  On the other hand, as shown in FIG. 1B, the inside of the amorphous alloy is an amorphous body 230, so that the crystal grains 210 and the grain boundaries 220 (see FIG. 1 (see (a)) does not exist. From this, the surface film 200 of the amorphous alloy has a relatively uniform thickness as shown in FIG. Thus, the state of the surface coating 200 is different between a normal metal or alloy and an amorphous alloy.

  During normal use of the secondary battery, the smaller the resistance generated by the surface coating 200, the smaller the internal resistance of the secondary battery, which is preferable. On the other hand, at the time of the nail penetration test, it is preferable that the resistance generated by the surface coating 200 is larger because the amount of Joule heat generated can be suppressed.

  Stress is applied to the current collector of the secondary battery. The magnitude of the stress is 0.01 to 40 MPa during normal use and 100 MPa or more during the nail penetration test.

  In a normal metal or alloy, there is an intersection 225 as shown in FIG. Further, among ordinary metals or alloys, the surface coating 200 is entirely thin in aluminum and copper. Therefore, even if the stress applied to the current collector increases, the conductivity of the surface coating 200 does not increase so much. However, even when the stress applied to the current collector is 0.01 to 40 MPa (corresponding to normal use), the conductivity is already sufficiently large, and the intersection 225 is an electron path. Therefore, the resistance generated by the surface coating 200 is small regardless of the stress applied to the current collector. Thus, when aluminum and copper are used for the current collector, the performance as a secondary battery is good during normal use, but the amount of Joule heat generated cannot be suppressed during the nail penetration test.

  On the other hand, the surface coating 200 is generally thick in stainless steel among ordinary metals or alloys. For this reason, when the stress applied to the current collector is about 0.01 MPa, the conductivity of the surface coating 200 is not good, and the intersecting portion 225 is hardly deformed, and the intersecting portion 225 is unlikely to be an electron path. Therefore, the resistance caused by the surface coating 200 remains high. However, as the stress applied to the current collector increases, the thickness of the surface coating 200 decreases and its conductivity increases. Further, when the intersecting portion 225 is deformed, the intersecting portion 225 becomes an electron path, and the resistance generated by the surface coating 200 is reduced. When the stress applied to the current collector becomes 100 MPa or more as in the nail penetration test, the resistance generated by the surface coating 200 is further reduced, and is equivalent to the case where aluminum and copper are used for the current collector. . For this reason, when stainless steel is used for the current collector, the amount of Joule heat generated cannot be suppressed during the nail penetration test.

  On the other hand, as shown in FIG. 1B, the amorphous alloy surface coating 200 has no intersection 225, has a relatively uniform thickness, and is dense. Therefore, when an amorphous alloy is used for the current collector, even if the stress applied to the current collector increases from the stress during normal use to the stress during the nail penetration test, the resistance generated by the surface coating 200 changes almost. do not do. The resistance generated by the surface coating 200 has no practical problem during normal use of the secondary battery, and can suppress the amount of Joule heat generated during the nail penetration test.

  The constituent requirements of the secondary battery of the present disclosure, which have been completed based on the knowledge described so far, will be described next.

<Secondary battery>
In the secondary battery of the present disclosure, the type of the secondary battery is not particularly limited as long as at least one of the positive electrode current collector and the negative electrode current collector includes an amorphous alloy. As described above, the effect of the secondary battery of the present disclosure is obtained by the fact that the surface film of the amorphous alloy is dense and the thickness thereof is relatively uniform. From this, the effect of the secondary battery of this indication can be acquired irrespective of the kind of secondary battery.

  Secondary batteries include lithium ion secondary batteries, lithium ion polymer secondary batteries, nickel / hydrogen secondary batteries, nickel / cadmium secondary batteries, nickel / iron secondary batteries, nickel / zinc secondary batteries, and silver oxide. -A zinc secondary battery etc. are mentioned. Among these, in the case of a lithium ion secondary battery, since the electric energy is large and the current that flows during a short circuit such as a nail penetration test is large, the effect of the secondary battery of the present disclosure is great. The lithium ion secondary battery may be an all solid lithium ion secondary battery, a non-aqueous electrolyte lithium ion secondary battery, or the like.

<Positive electrode current collector and negative electrode current collector>
In the secondary battery of the present disclosure, at least one of the positive electrode current collector and the negative electrode current collector includes an amorphous alloy. All of the positive electrode current collector may not be an amorphous alloy. For example, only the portion in contact with the positive electrode active material layer may be an amorphous alloy, and the tab portion is a metal or an alloy (excluding an amorphous alloy). Good.

  The amorphous alloy may be entirely amorphous or at least partially amorphous. In the amorphous alloy, the amorphous content is preferably 50% by volume or more. This is because if the amorphous content is 50% by volume or more, the surface coating is less likely to be locally thinned by the crystal grain boundaries. In this respect, the amorphous content is more preferably 65% by volume or more, and still more preferably 80% by volume or more. On the other hand, the fact that all of the amorphous alloy is amorphous leads to a significant increase in manufacturing cost. Even if the amorphous content in the amorphous alloy is 97% by volume or less, 95% by volume or less, or 90% by volume or less, there is no practical problem.

  The composition of the amorphous alloy is not particularly limited as long as at least a part of the alloy is amorphous and the amorphous alloy functions as a positive electrode current collector and a negative electrode current collector of the secondary battery. Examples of amorphous alloys include Fe-based amorphous alloys, Ni-based amorphous alloys, FeNi-based amorphous alloys, and CoCr-based amorphous alloys.

  As the amorphous alloy, Fe-based amorphous alloy, Ni-based amorphous alloy, and FeNi-based amorphous alloy are preferable. When Fe-based amorphous alloy, Ni-based amorphous alloy, or FeNi-based amorphous alloy is used for at least one of the positive electrode current collector and the negative electrode current collector, the temperature rise of the secondary battery can be reduced during a short circuit such as a nail penetration test. While being able to suppress, the performance as a secondary battery at the time of normal use is also comparatively high. In particular, when an Fe-based amorphous alloy is used for the positive electrode current collector and copper is used for the negative electrode current collector, the output of the secondary battery during normal use is also improved. This is because when the Fe-based amorphous alloy is used for the positive electrode current collector and copper is used for the negative electrode current collector, the contact resistance can be further reduced by setting the stress to 0.1 to 40 MPa.

  The Fe-based amorphous alloy means an amorphous alloy containing Fe as a main component. The Ni-based amorphous alloy means an amorphous alloy containing Ni as a main component. The FeNi amorphous alloy means an amorphous alloy mainly composed of Fe and Ni. The CoCr-based amorphous alloy means an amorphous alloy mainly composed of Co and Cr. The “main component” means a component (element) having the highest content (atomic%) in the alloy. For example, an amorphous alloy containing Fe as a main component has the highest Fe content in the alloy. An amorphous alloy containing Ni as a main component has the highest Ni content in the alloy. An amorphous alloy mainly composed of Fe and Ni has the highest total content of Fe and Ni in the alloy. In an amorphous alloy containing Co and Cr as main components, the total content of Co and Cr is the largest in the alloy.

  Regarding the composition of the Fe-based amorphous alloy, the Fe content is preferably 50 atomic% or more, more preferably 60 atomic% or more, and even more preferably 70 atomic% or more.

  Examples of the Fe-based amorphous alloy include an alloy containing 2 to 25 atomic% of Si and 2 to 25 atomic% of B, with the balance being Fe and inevitable impurities. About the minimum of content of Si, 4 atomic% is more preferable and 8 atomic% is still more preferable. On the other hand, the upper limit of the Si content is preferably 20 atomic%, and more preferably 10 atomic%. Moreover, about the minimum of content of B, 5 atomic% is more preferable and 10 atomic% is still more preferable. On the other hand, the upper limit of the B content is more preferably 20 atomic% and even more preferably 15 atomic% or less. This Fe-based amorphous alloy may be called an Fe—Si—B based amorphous alloy.

  In the above-described Fe-based amorphous alloy, C, Al, Cr, W, P, Mn, Zn, Ti, Nb, Ta, Mo, Cu, and rare earth elements are substituted for 0.1 to 8.0 atomic% of Fe. You may contain 1 or more types chosen from these. Even if these elements are contained in the Fe-based amorphous alloy in an amount of 0.1 to 8.0 atomic%, specific characteristics such as heat resistance and corrosion resistance are improved without impairing the effects of the secondary battery of the present disclosure. To do. The lower limit of the content of these elements may be 0.5 atomic%, 1.0 atomic%, or 3.0 atomic%. On the other hand, the upper limit of the content of these elements may be 6.0 atom%, 5.0 atom%, or 4.0 atom.

  Inevitable impurities refer to impurities inevitably contained in raw materials and / or manufacturing processes. The content of inevitable impurities is preferably 2 atomic percent or less, and more preferably 1 atomic percent or less.

  Regarding the composition of the Ni-based amorphous alloy, the Ni content is preferably 40 atomic% or more, more preferably 50 atomic% or more, and even more preferably 60 atomic% or more.

  Examples of the Ni-based amorphous alloy include an alloy containing 60 to 80 atomic% Ni, 2 to 15 atomic% Si, and 5 to 15 atomic% B, with the balance being inevitable impurities. It is done.

  Examples of the Ni-based amorphous alloy include 60 to 80 atomic% Ni, 2 to 15 atomic% Si, and 5 to 15 atomic% B, and further 2 to 20 atomic% Cr, 2 to 5 An alloy having a composition containing at least one selected from atomic percent Fe, 2 to 5 atomic percent W, and 15 to 20 atomic percent Co, with the balance being an inevitable impurity.

  Examples of the Ni-based amorphous alloy include an alloy containing 40 to 70 atomic% Ni, 15 to 20 atomic% B, and 10 to 15 atomic% Cr, with the balance being inevitable impurities. It is done.

  Examples of the Ni-based amorphous alloy include 40 to 70 atomic% Ni, 15 to 20 atomic% B, and 10 to 15 atomic% Cr, and 15 to 20 atomic% Co, 2 to 5 An alloy having a composition containing at least one element selected from atomic percent Fe and 2 to 5 atomic percent Mo, with the balance being an inevitable impurity.

  Examples of the Ni-based amorphous alloy include alloys containing 60 to 85 atomic% Ni and 15 to 20 atomic% P, with the balance being inevitable impurities.

  The Ni-based amorphous alloy contains 60 to 85 atomic% Ni and 15 to 20 atomic% P, and further contains 15 to 20 atomic% Cr, with the balance being inevitable impurities. An alloy is mentioned.

  Examples of the inevitable impurities of the Ni-based amorphous alloy described so far include C, Al, Mn, Zn, Ti, and Cu. Inevitable impurities refer to impurities inevitably contained in raw materials and / or manufacturing processes. The content of inevitable impurities is preferably 2 atomic percent or less, and more preferably 1 atomic percent or less.

  Regarding the composition of the FeNi-based amorphous alloy, the total content of Fe and Ni is preferably 60 atomic percent or more, and more preferably 70 atomic percent or more.

  Examples of the FeNi-based amorphous alloy include an alloy containing 25 to 45 atomic% Fe, 30 to 50 atomic% Ni, and 10 to 20 atomic% B, with the balance being inevitable impurities. .

  The FeNi-based amorphous alloy contains, for example, 25 to 45 atomic% Fe, 30 to 50 atomic% Ni, 10 to 20 atomic% B, and further contains 0 to 5 atomic% Mo and 0 to 3 atoms. % Co, 0-3 atomic% Cr, 0-3 atomic% Mn, Nb selected from 0-3 atomic%, 0-2 atomic% Si, and 0-2 atomic% C An alloy having a composition containing at least one kind and the balance being inevitable impurities can be mentioned. When Mo is selected in this FeNi-based amorphous alloy, this alloy may be called an Fe—Ni—Mo—B based amorphous alloy.

  Examples of the inevitable impurities of the FeNi-based amorphous alloy described so far include Al, Mn, Zn, Ti, and Cu. Inevitable impurities refer to impurities inevitably contained in raw materials and / or manufacturing processes. The content of inevitable impurities is preferably 2 atomic percent or less, and more preferably 1 atomic percent or less.

  Regarding the composition of the CoCr-based amorphous alloy, the total content of Co and Cr is preferably 50 atomic% or more, and more preferably 60 atomic% or more.

  Examples of the CoCr-based amorphous alloy include an alloy containing 60 to 80 atomic percent Co, 15 to 25 atomic percent Cr, and 5 to 15 atomic percent B, with the balance being inevitable impurities. It is done.

  The CoCr-based amorphous alloy contains, for example, 60 to 80 atomic% Co, 15 to 25 atomic% Cr, and 5 to 15 atomic% B, and further contains 2 to 5 atomic% Si. An alloy having a composition in which the balance is an inevitable impurity is used.

  The CoCr-based amorphous alloy contains, for example, 30 to 60 atomic% Co, 20 to 40 atomic% Cr, 5 to 15 atomic% B, and 5 to 15 atomic% W, with the remainder being inevitable impurities. An alloy having a composition of

  The CoCr-based amorphous alloy contains, for example, 30 to 60 atomic percent Co, 20 to 40 atomic percent Cr, 5 to 15 atomic percent B, and 5 to 15 atomic percent W. Alloy containing at least one selected from atomic percent Fe, 2-5 atomic percent Si, 2-5 atomic percent Ni, and 2-8 atomic percent C, with the balance being inevitable impurities Is mentioned.

  Examples of the inevitable impurities in the CoCr-based amorphous alloy described so far include C, Al, P, Mn, Zn, and Ti. Inevitable impurities refer to impurities inevitably contained in raw materials and / or manufacturing processes. The content of inevitable impurities is preferably 2 atomic percent or less, and more preferably 1 atomic percent or less.

  The Fe-based amorphous alloy, Ni-based amorphous alloy, FeNi-based amorphous alloy, and CoCr-based amorphous alloy that have been described so far include amorphous alloys used as soft magnetic materials. The positive electrode current collector and / or the negative electrode current collector of the secondary battery of the present disclosure need not be a soft magnetic material. However, an amorphous alloy used as a soft magnetic material often has an amorphous content of 50% by volume or more. Therefore, the surface film is relatively uniform and dense. For this reason, the amorphous alloy used as the soft magnetic material is suitable for use in the secondary battery of the present disclosure. Further, an alloy obtained by further adding an element for improving the magnetic properties to an amorphous alloy used as such a soft magnetic material can be used as a current collector of the secondary battery of the present disclosure. Examples of elements that improve magnetic properties include rare earth elements.

  In the secondary battery of the present disclosure, at least one of the positive electrode current collector and the negative electrode current collector contains an amorphous alloy, but the current collector not containing the amorphous alloy is made of a metal or alloy that is well-known as a secondary battery. Can be applied.

  For example, in an all-solid-state lithium ion secondary battery, as a positive electrode current collector, a current collector of various metals such as silver, copper, gold, aluminum, nickel, iron, stainless steel, titanium, or an alloy thereof Can be applied. From the viewpoint of chemical stability, the positive electrode current collector is preferably an aluminum current collector. About application of the metal or alloy about the positive electrode electrical power collector which does not contain an amorphous alloy, also in a non-aqueous electrolyte lithium ion secondary battery, it is the same as that of an all-solid-state lithium ion secondary battery.

  For example, in an all-solid-state lithium ion secondary battery, various metals such as silver, copper, gold, aluminum, nickel, iron, stainless steel, titanium, or alloys thereof may be used as the negative electrode current collector. it can. From the viewpoint of chemical stability, the negative electrode current collector is preferably a copper current collector. An alloy element may be added to copper within a range that does not impair the electrical characteristics of the secondary battery of the present disclosure, and a copper alloy current collector may be used. About application of the metal or alloy about the negative electrode collector which does not contain an amorphous alloy, also in a non-aqueous electrolyte lithium ion secondary battery, it is the same as that of an all-solid-state lithium ion secondary battery.

  As long as both the positive electrode current collector and the negative electrode current collector function as the current collector of the secondary battery, the form thereof is not particularly limited and may be a known form. For example, a thin plate, a thin piece (ribbon), a foil, etc. are mentioned. The amorphous alloy used for at least one of the positive electrode current collector and the negative electrode current collector is typically produced by a liquid quenching method. From this, as a form of the positive electrode current collector and / or the negative electrode current collector, a thin piece (ribbon), a foil, and the like are convenient. A method for producing an amorphous alloy used for at least one of the positive electrode current collector and the negative electrode current collector will be described later.

  Regardless of the type of the secondary battery of the present disclosure, the electrolyte includes a positive electrode current collector, a positive electrode active material layer, a separate layer, a negative electrode active material layer, and a negative electrode current collector in this order. . The positive electrode current collector and the negative electrode current collector are as described above, and the positive electrode active material layer, the separate layer, the negative electrode active material layer, and the electrolyte should be known for each type of secondary battery. Can do.

  Here, the case where the secondary battery of the present disclosure is, for example, an all-solid lithium ion secondary battery or a non-aqueous electrolyte lithium ion secondary battery will be described, but is not limited thereto.

  First, the case where the secondary battery of the present disclosure is an all-solid lithium ion secondary battery will be described. The all-solid-state lithium ion secondary battery includes a positive electrode current collector, a positive electrode active material layer, a solid electrolyte layer, a negative electrode active material layer, and a negative electrode current collector in this order. In the all solid lithium ion secondary battery, the solid electrolyte layer functions as a separate layer. Hereinafter, the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer will be described with respect to the all solid lithium ion secondary battery.

<Positive electrode active material layer of all-solid-state lithium ion secondary battery>
The raw material of the positive electrode active material layer contains a positive electrode active material, and optionally a conductive additive, a binder, and a solid electrolyte. For these, the following materials can be selected. In addition, about a solid electrolyte, the material quoted by a solid electrolyte layer can be used.

  As the positive electrode active material, at least one transition metal selected from manganese, cobalt, nickel, and titanium and a metal oxide containing lithium, such as lithium cobaltate, lithium nickelate, lithium manganate, or nickel cobalt lithium manganate Or the like, selected from a hetero-element substituted Li-Mn spinel, lithium titanate, lithium metal phosphate, or a combination thereof.

The positive electrode active material may be coated with a material that has lithium ion conductivity and can maintain the form of a coating layer that does not flow even when in contact with the active material or the separate layer. Specifically, the positive electrode active material may be coated with, for example, LiNbO ₃ , Li ₄ Ti ₅ O ₁₂ , Li ₃ PO ₄ or the like.

  The conductive assistant is selected from carbon materials such as VGCF (vapor grown carbon fiber), acetylene black, ketjen black (registered trademark), or carbon nanotube, or a combination thereof. Can do.

  The binder can be selected from polymer resins such as polyvinylidene fluoride (PVdF), butadiene rubber (BR), styrene butadiene rubber (SBR), or combinations thereof.

<Solid electrolyte layer of all-solid-state lithium ion secondary battery>
The raw material of the solid electrolyte layer contains a solid electrolyte. The following can be selected as a raw material for the solid electrolyte layer.

That is, the raw material of the solid electrolyte layer can be selected from materials that can be used as the solid electrolyte of the all-solid lithium ion secondary battery. Specifically, sulfide-based amorphous solid electrolyte, for example, Li ₂ S—P ₂ S ₅ , Li ₂ O.Li ₂ S.P ₂ S ₅ , Li ₂ S, P ₂ S ₅ , Li ₂ S _{-SiS 2, LiI-Li 2 S} -SiS 2, LiI-Li 2 S-P 2 S 5, LiI-Li 2 S-P 2 O 5, LiI-Li 3 PO 4 -P 2 S 5, or Li ₂ S—P ₂ S ₅ etc .; oxide-based amorphous solid electrolyte such as Li ₂ O—B ₂ O ₃ —P ₂ O ₅ or Li ₂ O—SiO ₂ ; crystalline oxide such as LiI, _{Li 3 N, Li 5 La 3} Ta 2 O 12, Li 7 Li 3 Zr 2 O 12, Li 6 BaLa 2 Ta 2 O 12, Li 3 PO (4-3 / 2w) N w (w <1) or the like; or, sulfide-based crystalline solid electrolyte, for _example, Li ₇ P 3 _{S 1} , _{Li 3.25} P _0.75 S ₄ such as glass ceramics, or _{Li 3.24} P _0.24 Ge _0.76 of S _4, etc. thio-LiSiO based crystal, and the like; or be combinations thereof it can.

<Anode active material layer of all-solid-state lithium ion secondary battery>
The raw material of the negative electrode active material layer contains a negative electrode active material, and optionally a conductive additive, a binder, and a solid electrolyte. For these, the following materials can be selected. In addition, about the solid electrolyte, the material quoted by the solid electrolyte layer can be used.

  The negative electrode active material is selected from materials capable of occluding and releasing metal ions, such as lithium ions, and is selected from carbon materials such as graphite and hard carbon, silicon materials such as Si and Si alloys, or combinations thereof. You can choose. It can also be selected from metallic materials such as indium, aluminum, or tin, or combinations thereof.

  When a graphite material that is a crystalline carbon material is used as the negative electrode active material, an amorphous coating may be applied to the surface of the graphite.

  As the conductive additive and binder of the negative electrode active material layer, the materials mentioned for the positive electrode active material layer can be used.

  Next, a case where the secondary battery of the present disclosure is a non-aqueous electrolyte lithium ion secondary battery will be described. The non-aqueous electrolyte lithium ion secondary battery includes a positive electrode current collector, a positive electrode active material layer, a separator layer, a negative electrode active material layer, and a negative electrode current collector in this order. In the non-aqueous electrolyte lithium ion secondary battery, the non-aqueous electrolyte impregnates the positive electrode active material layer, the separator layer, and the negative electrode active material layer.

<Positive electrode active material layer of non-aqueous electrolyte lithium ion secondary battery>
The raw material of the positive electrode active material layer contains a positive electrode active material and a solvent, and optionally a conductive additive and a binder. For these, the following materials can be selected.

As the positive electrode active material, at least one transition metal selected from manganese, cobalt, nickel and titanium and a metal oxide containing lithium, such as lithium cobaltate (LiCoO ₂ ), lithium manganate (LiMn ₂ O ₄ ), Mention may be made of lithium nickelate (LiNiO ₂ ) and combinations thereof, such as lithium nickel manganate and nickel cobalt lithium manganate. Examples of the nickel cobalt lithium manganate include LiNi _1/3 Co _1/3 Mn _1/3 O ₂ .

In the case of a non-aqueous electrolyte lithium ion secondary battery that operates at a high voltage, the positive electrode active material may be a nickel-manganese spinel-based positive electrode active material, such as Li _x Ni _0.5 Mn _1.5 O _{4− w} (0 <x <2, 0 ≦ w <2), in particular LiNi _0.5 Mn _1.5 O ₄ can be used. The transition metal site of the nickel-manganese spinel-based positive electrode active material may contain a substitution element such as titanium (Ti) or iron (Fe).

  As the solvent, an aprotic polar solvent that does not adversely affect the positive electrode active material contained in the positive electrode mixture slurry, particularly an aprotic polar organic solvent such as NMP (N-methyl-2-pyrrolidone) is used. it can.

  As an optional conductive aid, for example, a carbon-based conductive material, particularly carbon black such as acetylene black (AB) and ketjen black (registered trademark), graphite (graphite) can be used.

  As an optional binder, for example, a polymer-based binder such as polyvinylidene fluoride (PVDF), styrene butadiene rubber (SBR), polytetrafluoroethylene (PTFE), carboxymethyl cellulose (CMC), or the like can be used. From the viewpoint of improving the durability of the non-aqueous electrolyte lithium ion secondary battery, the binder is preferably a non-electrolyte, and PVDF is particularly preferable.

<Separate layer of non-aqueous electrolyte lithium ion secondary battery>
A well-known material (separator) can be used as a separate layer. As the separator, a porous polymer film such as a porous polyethylene film (PE), a porous polypropylene film (PP), a porous polyolefin film, or a porous polyvinyl chloride film can be used. Moreover, as a separator, a lithium ion or an ion conductive polymer electrolyte membrane can also be used. These separators can be used alone or in combination. From the viewpoint of increasing the battery output, it is preferable to use a three-layer coated separator in which a porous polyethylene film (PE) is sandwiched between two upper and lower porous polypropylene films (PP).

<Negative electrode active material layer of non-aqueous electrolyte lithium ion secondary battery>
The raw material of the negative electrode active material layer contains a negative electrode active material, and optionally a conductive additive and a binder.

  The raw material of the negative electrode active material layer contains a negative electrode active material and a solvent, and optionally a conductive additive and a binder. For these, the following materials can be selected.

  The negative electrode active material is a material capable of inserting and extracting lithium, for example, a powdery carbon material made of graphite or the like, or amorphous carbon-coated natural graphite obtained by coating natural graphite with amorphous carbon Etc. can be used.

  As the solvent, the conductive additive, and the binder, the materials mentioned for the positive electrode active material layer can be used. When styrene butadiene rubber (SBR) is used for the binder, it is preferable to use water as the solvent.

<Electrolytic solution of non-aqueous electrolyte lithium ion secondary battery>
A non-aqueous electrolyte is used as the electrolyte. The nonaqueous electrolytic solution may be a composition in which a supporting salt is contained in a nonaqueous solvent. Nonaqueous solvents include organic electrolytes, fluorine-based solvents, propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and two or more thereof The material selected from the group which consists of these can be mentioned.

  As the non-aqueous solvent, a fluorinated solvent such as a fluorinated carbonate is preferable. Specific fluorinated carbonates include methyl 2,2,2-trifluoroethyl carbonate (MFEC; Carbonic acid, methyl 2,2,2-trifluoroethyl ester; CAS 156783-95-8), and / or difluoro. Dimethyl carbonate (DFDMC) is preferred, and those mixed at a volume ratio of 50:50 are particularly preferred.

Supporting salts include LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiC (CF ₃ SO ₂ ) ₃ , LiI lithium A material selected from the group consisting of compounds (lithium salts) and combinations of two or more thereof can be given. From the viewpoint of improving battery voltage and durability, LiPF ₆ is preferred as the supporting salt.

<Method for manufacturing secondary battery>
If an amorphous alloy is used for at least one of the positive electrode current collector and the negative electrode current collector, a known method can be applied to the method for manufacturing a secondary battery of the present disclosure. As described above, the secondary battery of the present disclosure can be of any type as long as an amorphous alloy is used for at least one of the positive electrode current collector and the negative electrode current collector. Therefore, a known manufacturing method of each type of secondary battery can be applied to the secondary battery of the present disclosure.

  For example, when the secondary battery of the present disclosure is an all-solid lithium ion secondary battery, the following manufacturing method can be given. For example, the positive electrode current collector, the raw material of the positive electrode active material layer, the raw material of the solid electrolyte layer, the raw material of the negative electrode active material layer, and the negative electrode current collector are placed in this order in a mold and compressed.

  For example, when the secondary battery of the present disclosure is a non-aqueous electrolyte lithium ion secondary battery, the following manufacturing method may be mentioned. For example, a raw material such as a positive electrode active material is kneaded to prepare a slurry-like positive electrode mixture. Similarly, a raw material such as a negative electrode active material is kneaded to prepare a slurry-like negative electrode mixture. A positive electrode mixture is applied to both surfaces of the positive electrode current collector, the solvent in the positive electrode mixture is removed by drying, and a positive electrode active material layer is formed on both surfaces of the positive electrode current collector to form a positive electrode. Similarly, a negative electrode mixture is applied to both surfaces of the negative electrode current collector, the solvent in the negative electrode mixture is removed by drying, and a negative electrode active material layer is formed on both surfaces of the negative electrode current collector to form a negative electrode. A positive electrode and a negative electrode are sandwiched or wound between separators, and this is charged into a container containing a non-aqueous electrolyte.

  The amorphous alloy used for the positive electrode current collector and / or the negative electrode current collector can be produced by a known method. Examples of the method for producing an amorphous alloy include a single roll method and a twin roll method. When casting a thin piece (ribbon) by the single roll method or the twin roll method, the thin piece discharged from the single roll or the double roll may be continuously rolled for the casting control.

  Hereinafter, the secondary battery of the present disclosure will be described more specifically with reference to examples and comparative examples. Note that the secondary battery of the present disclosure is not limited to these.

(Sample preparation)
A medium-sized (0.24 Ah) all-solid-state lithium ion secondary battery was produced as a sample. FIG. 2 is a schematic view showing a longitudinal section of a sample of an all-solid lithium ion secondary battery. The sample of the all-solid-state lithium ion secondary battery 100 includes a positive electrode current collector 10, a positive electrode active material layer 20, a solid electrolyte layer 30, a negative electrode active material layer 40, and a negative electrode current collector 50 in this order. The positive electrode current collector 10, the raw material of the positive electrode active material layer 20, the raw material of the solid electrolyte layer 30, the raw material of the negative electrode active material layer 40, and the negative electrode current collector 50 are placed in this order in a mold and compressed. Thus, a sample of the all solid lithium ion secondary battery 100 was produced. About the raw material of the positive electrode active material layer 20, the raw material of the solid electrolyte layer 30, and the raw material of the negative electrode active material layer 40, the positive electrode active material layer 20, the solid electrolyte layer 30, and the negative electrode active material layer 40 are respectively 50.3 micrometers, 39 The required amount of each raw material was charged into the mold to have thicknesses of .8 μm and 30.0 μm.

  FIG. 3 is a schematic diagram for three-dimensionally explaining the structure of the sample of the all-solid-state lithium ion secondary battery 100 shown in FIG. In FIG. 3, the positive electrode current collector 10, the positive electrode active material layer 20, the solid electrolyte layer 30, the negative electrode active material layer 40, and the negative electrode current collector 50 are respectively shown so that the structure of the all solid lithium ion secondary battery 100 can be easily understood. Are shown separately for convenience. In addition, each of the positive electrode current collector 10, the positive electrode active material layer 20, the solid electrolyte layer 30, the negative electrode active material layer 40, and the negative electrode current collector 50 is shown moving in the left-right direction for convenience. As shown in FIG. 3, the positive electrode current collector 10 and the negative electrode current collector 50 have tab portions 12 and 52, respectively.

  Table 1 shows combinations of materials constituting the positive electrode current collector 10 and the negative electrode current collector 50. Table 1 also shows the thickness of each current collector. As the Fe-based amorphous alloy foil in Table 1, Metglas (registered trademark) 2605S3A manufactured by Hitachi Metals, Ltd. was used. This alloy is an Fe—Si—B based amorphous alloy manufactured by a single roll method. Further, as the FeNi-based amorphous alloy foil in Table 1, Metglas (registered trademark) 2826MB manufactured by Hitachi Metals, Ltd. was used. This alloy is a Ni—Fe—Mo—B based amorphous alloy produced by a single roll method.

  The positive electrode active material layer contains 84.7% by mass of nickel cobalt lithium manganate, 13.4% by mass of sulfide-based amorphous solid electrolyte, 0.6% by mass of binder, and 1.3% by mass of VGCF. Made. In the positive electrode active material layer, the active material was 75% by volume, and the solid electrolyte was 25% by volume.

  The solid electrolyte layer was prepared by blending 99.6% by mass of a sulfide-based amorphous solid electrolyte and 0.4% by mass of a binder.

  The negative electrode active material layer was prepared by blending 54.5 mass% Si, 42.3 mass% sulfide-based amorphous solid electrolyte, 1.1 mass% binder, and 2.1 mass% VGCF. In the negative electrode active material layer, the active material was 55% by volume and the solid electrolyte was 45% by volume.

<Evaluation>
A nail penetration test was performed on the samples of Example 1 and Comparative Examples 1 and 2. Moreover, the output (mW / cm < ² >) was measured about the sample of Examples 1-4 and Comparative Examples 1-2. Further, the surface resistance of the combination of the positive electrode current collector and the negative electrode current collector shown in Table 1 was measured.

  The nail penetration test was performed in consideration of the current flowing from the secondary battery other than the specimen secondary battery at the short-circuited portion. FIG. 4 is an explanatory diagram showing an outline of the nail penetration test apparatus. The specimen secondary battery 60 is stored in the first container 70, and the electron supply secondary battery 85 is stored in the second container 80. The specimen secondary battery 60 was formed by stacking two single batteries. As the secondary battery 85 for electron supply, 36 single cells were stacked. The specimen secondary battery 60 and the electron supply secondary battery 85 are connected in parallel, and an ammeter 90 is connected between them. The test was performed in a state where the temperature inside the first container 70 and the second container 80 was 25 ° C., and the SOC (State of Charge) of the specimen secondary battery 60 was 100%. A test was performed by inserting a nail 95 having a diameter of 8 mm and a tip angle of 60 degrees into a nail penetration position 72 near the center of the specimen secondary battery 60 at a speed of 0.5 mm / second.

<Evaluation results>
Regarding the nail penetration test, for the batteries of Comparative Examples 1 and 2, the temperature of the secondary battery increased rapidly after nail penetration, whereas for the battery of Example 1, the temperature increase was sufficiently suppressed. It had been. The amount of temperature increase of the battery of Example 1 was about 17% of the amount of temperature increase of the battery of Comparative Example 1.

  FIG. 5 is a graph showing the relationship between stress and contact resistance for the combinations of the positive electrode current collector and the negative electrode current collector of Examples 1-2 and Comparative Examples 1-2. FIG. 6 is a graph showing the relationship between stress and contact resistance for the combination of the positive electrode current collector and the negative electrode current collector of Example 1, Examples 3 to 4, and Comparative Examples 1 and 2.

  In a secondary battery, the combination of a positive electrode current collector and a negative electrode current collector that satisfy both the performance during normal use and the suppression of temperature rise during the nail penetration test is determined by the stress applied to the current collector, It can be evaluated by the relationship between the contact resistance of the body and the negative electrode current collector.

  During normal use of the secondary battery, the positive electrode current collector is in contact with the positive electrode active material, and the negative electrode current collector is in contact with the negative electrode active material. There is no contact. Nevertheless, the combination of the positive electrode current collector and the negative electrode current collector that satisfy the performance during normal use is determined based on the stress applied to the current collector and the surface resistance of the positive electrode current collector and the negative electrode current collector. The reason why the relationship can be evaluated is considered as follows.

  The resistance generated by the surface coating 200 in FIG. 1 has a great influence on the performance during normal use, and the resistance generated by the surface coating 200 changes depending on the stress applied to the surface coating 200. This is because the stress applied to the surface coating 200 changes in the same manner regardless of the presence or absence of the positive electrode active material and the negative electrode pressure material.

  5 and 6, the broken line indicates the stress range during normal use of the secondary battery and the allowable range of contact resistance at that time, and the alternate long and short dash line indicates the stress range in the short-circuit mode such as a nail penetration test, The allowable range of contact resistance is shown. The “permissible range of contact resistance” means a range in which the performance as a secondary battery can be maintained during normal use, and suppresses the temperature rise of the secondary battery in a short-circuit mode such as a nail penetration test. It means the range that can be. FIG. 7 is a graph showing the outputs of the secondary batteries of Example 1, Examples 3-4, and Comparative Examples 1-2. In FIG. 7, the output of the secondary battery of Comparative Example 1 is normalized as 100.

  From the results of the nail penetration test and FIGS. 5 to 6, when an amorphous alloy is used for at least one of the positive electrode current collector and the negative electrode current collector, the performance during normal use of the secondary battery is maintained and the nail penetration test or the like It can be understood that the temperature rise of the secondary battery can be suppressed during the short circuit.

  Further, as can be seen from FIG. 6, when an Fe-based amorphous alloy is used for the positive electrode current collector and copper is used for the negative electrode current collector, the contact resistance can be further reduced when the stress is 0.1 to 40 MPa. As can be seen from FIG. 7, when an Fe-based amorphous alloy is used for the positive electrode current collector and copper is used for the negative electrode current collector, the output of the secondary battery is also improved.

  In order to suppress the temperature rise of the secondary battery at the time of a short circuit such as a nail penetration test while maintaining the performance of the secondary battery during normal use, the relationship between the stress and the surface resistance is shown by the broken line in FIG. 5 and FIG. It suffices if it is within the range surrounded by the alternate long and short dash line. The reason why the results of FIGS. 5 and 6 are obtained is considered that the surface film of the amorphous alloy is relatively uniform and dense as described above. Therefore, it can be considered that the effect of the secondary battery of the present disclosure obtained by including at least one of the positive electrode current collector and the negative electrode current collector contains an amorphous alloy does not depend on the type of the secondary battery.

  From the above results, the effect of the secondary battery of the present disclosure was confirmed.

DESCRIPTION OF SYMBOLS 10 Positive electrode collector 12 Tab part 20 Positive electrode active material layer 30 Solid electrolyte layer 40 Negative electrode active material layer 50 Negative electrode collector 52 Tab part 60 Specimen secondary battery 70 First container 72 Nail penetration position 80 Second container 85 Electron Secondary battery for supply 90 Ammeter 95 Nail 100 All-solid lithium ion secondary battery 200 Surface coating 210 Crystal grain 220 Crystal grain boundary 225 Intersection 230 Amorphous body

Claims (2)

  A secondary battery in which at least one of a positive electrode current collector and a negative electrode current collector contains an amorphous alloy.   The secondary battery according to claim 1, wherein the positive electrode current collector includes an Fe-based amorphous alloy, and the negative electrode current collector includes copper or a copper alloy.

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