JP2017168259A - Nonaqueous electrolyte battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte battery which is superior in negative electrode flatness and charge and discharge efficiencies, and which can be charged repeatedly.SOLUTION: A nonaqueous electrolyte battery according to the present invention comprises: a flat plate like electrode body arranged by laminating positive and negative electrodes through a separator; and a nonaqueous electrolyte solution. The nonaqueous electrolyte battery has the negative electrode of which only one face is opposed to the positive electrode. The negative electrode of which only the one face is opposed to the positive electrode is composed of a laminate including: a metal base material layer which is not alloyed with Li; an Al metal layer (A) joined to one face of the metal base material layer; and an Al metal layer (B) joined to the other face of the metal base material layer. The Al metal layer (A) is disposed on a side fronting the positive electrode, in which a Li-Al alloy is formed on at least the face on the side fronting the positive electrode. The metal base material layer is 35 μm or less in thickness, and the Al metal layer (B) is 10-35 μm in thickness.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a non-aqueous electrolyte battery that can be repeatedly charged and has excellent negative electrode flatness and charge / discharge efficiency.

  As a non-aqueous electrolyte battery (secondary battery) that can be used by repeatedly charging and discharging, a negative electrode mixture layer containing a negative electrode active material such as a carbon material is formed on the surface of a current collector. What you have is known. In such a nonaqueous electrolyte battery, for example, a laminated electrode body in which a plurality of positive electrodes and a plurality of negative electrodes are alternately stacked via a separator is used for the purpose of improving capacity and load characteristics. (Patent Document 1, etc.).

  In the laminated electrode body as described above, when the negative electrode is disposed in the outermost layer, the surface of the outermost negative electrode that does not face the positive electrode hardly participates in the battery reaction. Therefore, it is not necessary to form a negative electrode mixture layer from the surface of the battery reaction on the surface of the negative electrode disposed in the outermost layer that does not face the positive electrode. However, a negative electrode having a negative electrode mixture layer only on one side of the current collector is likely to warp during production. Therefore, in patent document 1, the negative electrode arrange | positioned in the outermost layer uses what formed the negative mix layer (negative electrode active material layer) on both surfaces of the electrical power collector, and suppresses generation | occurrence | production of the said curvature. Has proposed.

  On the other hand, in a non-aqueous electrolyte battery that is repeatedly used for charging and discharging, it is also possible to use a lithium alloy such as metallic lithium or a Li—Al (lithium-aluminum) alloy as a negative electrode active material (for example, Patent Documents). 2).

  In Patent Document 2, in a secondary battery using a Li—Al alloy as a negative electrode active material, it is pointed out that there is a problem of characteristic deterioration due to the negative electrode becoming brittle due to the formation of the Li—Al alloy. Stability of organic electrolyte secondary battery with Li-Al alloy in the negative electrode by constructing the negative electrode using a clad material of a dissimilar metal that can occlude and release lithium and lithium does not occlude and release lithium It is proposed to realize.

JP 2009-199912 A JP-A-8-293302

  By the way, in a battery using a Li—Al alloy as a negative electrode active material, for example, when Al metal or an Al alloy is used for the negative electrode and at least a part of Al is reacted with Li to form a Li—Al alloy, Since it expand | swells greatly, there exists a problem that a negative electrode deform | transforms and flatness is easy to be impaired.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a non-aqueous electrolyte battery that can be repeatedly charged and is excellent in negative electrode flatness and charge / discharge efficiency.

  The non-aqueous electrolyte battery of the present invention that can achieve the above object includes a flat electrode body in which a positive electrode and a negative electrode are stacked with a separator interposed therebetween, and a non-aqueous electrolyte, and only one side faces the positive electrode. The negative electrode having only one surface facing the positive electrode has a metal base layer not alloyed with Li, an Al metal layer (A) bonded to one side of the metal base layer, A laminated body containing an Al metal layer (B) bonded to the other surface of the metal substrate layer, the Al metal layer (A) being disposed on the side facing the positive electrode, and at least the A Li—Al alloy is formed on the surface facing the positive electrode, the thickness of the metal base layer is 35 μm or less, and the thickness of the Al metal layer (B) is 10 to 35 μm. It is characterized by.

  According to the present invention, it is possible to provide a non-aqueous electrolyte battery that can be repeatedly charged and is excellent in negative electrode flatness and charge / discharge efficiency.

It is a top view which represents typically an example of the nonaqueous electrolyte battery of this invention. It is the II sectional view taken on the line of FIG. FIG. 3 is a partially enlarged view of FIG. 2.

  The nonaqueous electrolyte battery of the present invention is a flat electrode body in which a positive electrode and a negative electrode are stacked with a separator interposed therebetween (a structure in which the electrode and the plane of the separator are stacked substantially in parallel without being wound. A laminated electrode body having one positive electrode and one negative electrode, one positive electrode and two negative electrodes, and a plurality of positive electrodes and a plurality of negative electrodes laminated alternately. Case).

  And as a negative electrode which comprises the said electrode body, it has at least what has only one side facing a positive electrode, and the negative electrode which only this one side opposes a positive electrode is a metal base material layer which does not alloy with Li, this metal A laminate comprising an Al metal layer (A) bonded to one side of a base material layer and an Al metal layer (B) bonded to the other side of the metal base layer, and an Al metal layer (A) Is disposed on the side facing the positive electrode, and a Li—Al alloy is formed on at least the surface facing the positive electrode.

  In the nonaqueous electrolyte battery of the present invention, the Li-alloy in the negative electrode acts as an active material. Thus, for example, even when used in a high temperature environment such as in-vehicle use, high storage characteristics and high capacity can be realized, and charging can be performed a certain number of times.

  In the nonaqueous electrolyte battery of the present invention, the current collector is used for the purpose of stabilizing the shape of the negative electrode during discharge and enabling the next charge.

  In the present invention, an Al metal layer for forming a Li—Al alloy (Al foil or the like. In addition, unless otherwise specified, an Al foil includes an Al alloy foil. The same shall apply hereinafter) and a current collector. Metal base layer not alloyed with Li acting (Cu foil and the like. Note that the foil for the metal base layer such as Cu foil includes an alloy foil such as Cu alloy foil unless otherwise specified. The same applies hereinafter). In addition, a Li layer (Li foil or the like; unless otherwise specified, the Li foil includes a Li alloy foil; the same shall apply hereinafter) is laminated on the surface of the Al metal layer. A method of reacting Li of the Li layer and Al of the Al metal layer, or a joined body of the Al metal layer and the metal base layer is used as it is for assembling a battery, and the Al metal layer is obtained by charging after assembly. Of lithium in non-aqueous electrolyte and electrochemistry By a method of reacting to, in the above-Al metal layer of at least a positive electrode and a counter negative electrode Li-Al alloy on the surface side is formed to be, it is made possible to suppress an increase in internal resistance.

  By the way, considering only the charge / discharge reaction of the battery, in the negative electrode facing the positive electrode only on one side, the surface opposite to the surface facing the positive electrode hardly participates in the charge / discharge reaction. Therefore, in such a negative electrode, it is conceivable that an Al metal layer is bonded only to one surface of the metal substrate layer, and a Li—Al alloy is formed on the surface of the Al metal layer (a surface facing the positive electrode). However, as described above, since the volume of the Al metal layer formed with the Li—Al alloy expands to, for example, twice or more, deformation such as warping of the negative electrode occurs.

  Therefore, in the nonaqueous electrolyte battery of the present invention, the negative electrode facing the positive electrode only on one side is bonded, the Al metal layer (A) is bonded to one side of the metal base layer, and the Al metal layer (B) is bonded to the other side. In this laminated body, a Li—Al alloy was formed on at least the surface facing the positive electrode of the Al metal layer (A) that is the layer facing the positive electrode. In this case, even if the Al metal layer (A) expands greatly due to the formation of the Li—Al alloy, deformation of the negative electrode can be suppressed by the action of the Al metal layer (B). It becomes possible to improve the charge / discharge cycle characteristics of the battery.

  However, when the formation of the Li-Al alloy proceeds even in the Al metal layer (B) that does not face the positive electrode due to the charging of the battery, the Li cannot return to the positive electrode at the next discharge, and becomes an irreversible capacity. Efficiency will decrease. Such a problem becomes particularly prominent when the metal base layer not directly related to the battery capacity is thinned to improve the energy density of the battery, for example. In addition, when the metal base layer is thinned, deformation such as warping of the negative electrode due to volume expansion accompanying the formation of the Li—Al alloy in the Al metal layer (A) is likely to occur.

  Therefore, in the present invention, in the negative electrode having a thin metal base layer, by specifying the thickness of the Al metal layer (B), the irreversible capacity is made as small as possible to increase the charge / discharge efficiency, and the negative electrode This makes it possible to achieve both improved flatness.

  As described above, the electrode body according to the non-aqueous electrolyte battery of the present invention includes one positive electrode and one negative electrode, one positive electrode and two negative electrodes, and a plurality of positive electrodes. Although the case where a plurality of negative electrodes are alternately stacked is included, at least one of the negative electrodes is opposed to the positive electrode only on one side. For example, when the number of positive and negative electrodes is one each, the negative electrode has only one side facing the positive electrode, and when the number of negative electrodes is two or more, the electrode At least one of the electrodes arranged on the outermost layer of the body is used as a negative electrode, and the negative electrode that has only one surface facing the positive electrode is used. In an electrode body having a plurality of negative electrodes, only one of the electrodes on the outermost layer may be a negative electrode having only one surface facing the positive electrode (in this case, the other of the electrodes on the outermost layer is only one surface) May be a positive electrode facing the negative electrode), and the outermost electrode may be a negative electrode having only one surface facing the positive electrode.

  The negative electrode according to the non-aqueous electrolyte battery uses a laminated metal foil (for example, a clad material) in which an Al metal layer is bonded to both surfaces of the metal base layer, and the Al metal layer on the side facing the positive electrode in the battery, It can be formed by forming a Li—Al alloy on at least the surface facing the positive electrode to form an Al metal layer (A).

  And in the negative electrode which only one side opposes a positive electrode among the negative electrodes which concern on a nonaqueous electrolyte battery, the layer of the side facing a positive electrode among both Al metal layers joined to the metal base material layer is Li-. The Al metal layer (A) on which the Al alloy is formed becomes the other, and the other becomes the Al metal layer (B). On the other hand, in the negative electrode related to the non-aqueous electrolyte battery, both of the Al metal layers bonded to the metal base layer are Al in which a Li—Al alloy is formed, in which both surfaces face the positive electrode. It becomes a metal layer (A).

  The thickness of the metal base material layer of the negative electrode related to the nonaqueous electrolyte battery, that is, the thickness of the metal base material layer of the laminated metal foil used for forming the negative electrode is determined by the occupation of the metal base material layer in the battery internal volume. From the viewpoint of reducing the portion as much as possible and improving the energy density of the battery, for example, it is 35 μm or less, and preferably 25 μm or less. However, if the metal base layer is too thin, the effect of improving the flatness of the negative electrode may be reduced. Therefore, from the viewpoint of further improving the effect of increasing the flatness of the negative electrode, the thickness of the metal substrate layer possessed by the negative electrode, that is, the thickness of the metal substrate layer possessed by the laminated metal foil used for forming the negative electrode is 10 μm or more. It is preferable that

  In addition, the thickness of the Al metal layer (B) included in the negative electrode of the non-aqueous electrolyte battery, that is, the thickness of the Al metal layer included in the laminated metal foil used for forming the negative electrode is determined by the Li − in the Al metal layer (B). The portion where the formation of the Al alloy is likely to proceed (the end in the thickness direction of the Al metal layer (B)) is reduced to suppress the formation of the Li-Al alloy in the Al metal layer (B), thereby reducing the irreversible capacity of the battery. From the viewpoint of reducing and increasing the charge / discharge efficiency, it is 35 μm or less, and preferably 20 μm or less. Moreover, the thickness of the Al metal layer (B) of the negative electrode related to the nonaqueous electrolyte battery, that is, the thickness of the Al metal layer of the laminated metal foil used for forming the negative electrode improves the flatness of the negative electrode. From a viewpoint of ensuring, it is 10 micrometers or more, and it is preferable that it is 15 micrometers or more. In addition, among the Al metal layers in the laminated metal foil, the thickness of the Al metal layer for forming the Al metal layer (A) for generating the Li—Al alloy is also set to the thickness of Al for forming the Al metal layer (B). Similarly to the metal layer, it is preferably 10 μm or more, more preferably 15 μm or more, preferably 35 μm or less, more preferably 20 μm or less.

  The thickness of the metal base layer and the Al metal layer [Al metal layer (B)] referred to in the present specification is obtained by observing the cross section of the sample whose thickness is measured with a scanning electron microscope (SEM) at a magnification of 1000 times. In addition, it means an average value calculated from the thickness obtained from any five locations of these layers. The thickness of the Al metal layer (B) may be grasped by the thickness of the Al metal layer in the laminated metal foil used for forming the negative electrode, but when measuring the thickness of the Al metal layer (B) of the actual negative electrode In the case where a Li-Al alloy is formed and an expanded part is generated, the thickness of the Al metal layer (B) is measured excluding the part.

  In order to generate a Li—Al alloy in the Al metal layer related to the laminated metal foil for forming the negative electrode, any of the following first and second methods may be adopted.

  The first method of forming the negative electrode according to the non-aqueous electrolyte battery of the present invention includes a metal base layer that is not alloyed with Li (hereinafter simply referred to as “base layer”) and an Al metal layer (hereinafter simply referred to as “ A laminate in which a Li layer is formed by a method such as bonding a Li foil to the surface of an Al layer of a laminated metal foil formed by joining an Al layer ”(hereinafter referred to as“ negative electrode precursor ”). Is used.

The base material layer can be composed of a metal such as Cu, Ni, Ti, or Fe, or an alloy of these elements and other elements (however, an alloy that does not react with Li, such as stainless steel). In order to suppress the expansion of the negative electrode during charging (and the deformation of the negative electrode such as warpage accompanying it) even better even if the material layer is made thinner, the substrate layer is made of a metal selected from nickel, titanium and iron, or Like the alloy, it is preferably made of a material having a high tensile strength, and is preferably made of a material having a tensile strength at room temperature of 400 N / mm ² or more.

That is, in a coin-type battery or the like having a relatively small electrode area, even if the base material layer is made of a material having a low tensile strength such as Cu (tensile strength: 220 N / mm ² ), the influence due to the expansion of the negative electrode. Therefore, for example, a battery having a predetermined characteristic can be formed by resistance welding the base material layer to the sealing plate. However, when the area of the electrode is increased, or when a plurality of negative electrodes are laminated In such cases, deterioration of the battery characteristics caused by deformation of the negative electrode such as warpage caused by expansion of the negative electrode accompanying charging / discharging of the battery tends to increase. On the other hand, the base material layer is made of a metal selected from Ni, Ti and Fe, such as Ni (490 N / mm ² ), Ti (410 N / mm ² ), SUS304 (600 N / mm ² ), or an alloy thereof. Thus, even if it is thin, an excellent expansion suppression effect (negative electrode deformation suppression effect) can be obtained. In particular, the area of the Al metal layer (A) (when there are a plurality of layers) is 10 cm ² or more. In such a case, the effect of using the material becomes more remarkable.

On the other hand, in order to reduce the impedance of the negative electrode, the base material layer should be composed of a material having a low volume resistivity at room temperature, and the volume resistivity should be 80 × 10 ⁻⁶ Ω · cm or less. More preferred is a material having a volume resistivity of 30 × 10 ⁻⁶ Ω · cm or less, and particularly preferred is a material having a volume resistivity of 15 × 10 ⁻⁶ Ω · cm or less.

The volume resistivity of the material is Ni: 6.8 × 10 ⁻⁶ Ω · cm, Ti: 55 × 10 ⁻⁶ Ω · cm, and SUS304: 72 × 10 ⁻⁶ Ω · cm, respectively. From the point of view, it is particularly preferable that the base material layer is made of Ni or its alloy.

  The Al layer can be composed of pure Al or an Al alloy having an additive element for the purpose of improving the strength.

  For the formation of the Li layer, a method of attaching a Li foil to the surface of the Al layer, a method of forming a vapor deposition film, or the like can be used.

  In the non-aqueous electrolyte battery in which the negative electrode is formed using the negative electrode precursor, Li in the Li foil and Al in the Al layer reacted in the presence of the non-aqueous electrolyte, and the Li foil in the Al layer was bonded. A Li—Al alloy is generated on the surface (separator side), and becomes an Al metal layer (A). That is, a Li—Al alloy formed in the nonaqueous electrolyte battery is present on at least the surface of the Al metal layer (A) of the negative electrode facing the positive electrode (the surface on the Li foil side).

  And in the laminated body formed by bonding the laminated metal foil formed by bonding the base material layer and the Al layer and the Li foil, the surface of the Al layer on both sides of the base material layer (the base material layer and Li foil is bonded to the non-bonded surface.

  In the following, the case where the base material layer is Cu (Cu foil) and the case where the base material layer is Ni (Ni foil) will be described as an example, but the base material layer is a material other than Cu or Ni. Is the same.

  The Cu layer related to the laminated metal foil formed by joining the Cu layer and the Al layer includes a layer made of Cu (and inevitable impurities) and Zr, Cr, Zn, Ni, Si, P, etc. as alloy components. A layer composed of Cu alloy with the balance being Cu and inevitable impurities (the content of the alloy components is, for example, 10% by mass or less, preferably 1% by mass or less in total).

  As the Ni layer related to the laminated metal foil formed by joining the Ni layer and the Al layer, a layer made of Ni (and inevitable impurities), Zr, Cr, Zn, Cu, Fe, Si, P, etc. as alloy components And the balance is Ni and an inevitable impurity Ni alloy (the content of the alloy components is, for example, 20% by mass or less in total).

  Furthermore, as a laminated metal foil formed by joining a Cu layer and an Al layer, or an Al layer related to a laminated metal foil formed by joining a Ni layer and an Al layer, a layer made of Al (and inevitable impurities) Al alloy containing Fe, Ni, Co, Mn, Cr, V, Ti, Zr, Nb, Mo, etc. as the alloy component, the balance being Al and inevitable impurities (content of the alloy component is, for example, in total 50% by mass or less).

  In the laminated metal foil formed by joining the Cu layer and the Al layer or the laminated metal foil formed by joining the Ni layer and the Al layer, the ratio of the Li—Al alloy serving as the negative electrode active material is set to a certain level or more. Therefore, when the thickness of the Cu layer or Ni layer as the base material layer is 100, the thickness of the Al layer (however, when the Al layer is bonded to both sides of the Cu layer or Ni layer as the base material layer) Is the thickness per side. The same shall apply hereinafter.) Is preferably 30 or more, more preferably 50 or more, and even more preferably 70 or more. In addition, in order to enhance the current collecting effect and sufficiently hold the Li-Al alloy, a laminated metal foil formed by joining a Cu layer and an Al layer or a laminated metal layer formed by joining a Ni layer and an Al layer In the metal foil, the thickness of the Al layer is preferably 400 or less, more preferably 300 or less, and 200 or less when the thickness of the Cu layer or Ni layer as the base material layer is 100. Particularly preferred is 180 or less.

  As a Li foil used for the negative electrode precursor, a foil made of Ll (and inevitable impurities) and Fe, Ni, Co, Mn, Cr, V, Ti, Zr, Nb, Mo, etc. as a total of 40 masses as alloy components Examples include a foil made of a Li alloy that is contained in an amount of not more than% and the balance is Li and inevitable impurities.

  In addition to the method of forming the negative electrode precursor having a configuration in which a Li foil is bonded to the surface of the multilayer metal foil, the Al metal layer (A) of the negative electrode is formed as a second method, the multilayer metal foil is directly used as the negative electrode precursor. The Al metal layer (A) constituting the negative electrode can also be formed by a method of assembling the battery using the body and charging the assembled battery.

  That is, at least the positive electrode is made to react with the lithium ions in the nonaqueous electrolyte by electrochemically reacting Al on the surface of the Al metal layer of the laminated metal foil facing at least the positive electrode by charging the battery. It is also possible to use an Al metal layer (A) in which a Li—Al alloy is formed on the side surface.

  According to the second method in which the laminated metal foil to which no Li foil is bonded is used as the negative electrode precursor, the battery manufacturing process can be simplified. However, by forming the Al metal layer (A) using the negative electrode precursor, the irreversible capacity of the Li-Al alloy is offset by the Li of the Li layer of the negative electrode precursor. In order to achieve this, it is preferable to form the negative electrode by the first method (form the Al metal layer (A) of the negative electrode). Also, the battery is assembled using the negative electrode precursor according to the first method, and further charged. The negative electrode may be formed (the Al metal layer (A) of the negative electrode is formed).

  In a battery having, as a non-aqueous electrolyte battery according to the present invention, a negative electrode including a laminate including a metal base layer not alloyed with Li and an Al metal layer (A) bonded to the metal base layer. From the viewpoint of maintaining a good crystal structure of the substance acting as the negative electrode active material and stabilizing the potential of the negative electrode to ensure better storage characteristics, any of the first method and the second method is used. Even when the negative electrode Al metal layer (A) is formed by the above, the Li content when the total of Li and Al in the negative electrode Al metal layer (A) is 100 atomic% is 48 atomic%. It is preferable to use a battery in the following range. That is, when charging the battery, it is preferable to terminate the charging in a range where the Li content of the Al metal layer (A) is 48 atomic% or less, and charging is performed in a range where the Li content is 40 atomic% or less. It is more preferable to terminate the charge, and it is even more preferable to terminate the charge within a range of 35 atomic% or less.

  The Al layer of the laminated metal foil may be entirely alloyed with Li and act as an active material, but the Al metal layer (A) is not formed by alloying the base layer side of the Al layer with Li. It is more preferable to have a laminated structure of the Li—Al alloy layer on the side facing the positive electrode and the Al layer remaining on the base layer side.

  That is, by terminating charging in the above state, the separator side (positive electrode side) of the Al layer is reacted with Li to form a Li-Al alloy (a mixed phase or β phase of α and β phases), On the other hand, the vicinity of the joint portion of the Al layer with the base material layer is presumed to remain in the original Al layer without substantially reacting with Li, or the Li content is lower than the separator side, It is considered that excellent adhesion between the original Al layer and the base material layer can be maintained, and the Li—Al alloy formed on the separator side can be easily held on the base material layer. In particular, it is more preferable to stop the charging in a state where the α phase is mixed in the Li—Al alloy formed on the separator side of the Al layer.

  In the present specification, “Al substantially not alloyed with Li” means that the Al layer does not contain Li, or the state of α phase in which Li is dissolved in a range of several at% or less. "Substantially do not react with Li" means that Al is maintained in the α-phase state, including the state where Li is dissolved in a range of several at% or less. And

  In the nonaqueous electrolyte battery of the present invention, from the viewpoint of further increasing the capacity and heavy load discharge characteristics, the Li content when the total of Li and Al is 100 atomic% is 15 atomic% or more. The battery is preferably charged to such a range, more preferably the battery is charged to a range of 20 atomic% or more, and still more preferably the battery is charged to a range of 30 atomic% or more.

  Furthermore, it is desirable that the negative electrode according to the non-aqueous electrolyte battery terminates the discharge in the state where the Al metal phase (α phase) and the Li—Al alloy phase (β phase) coexist. The volume change of the negative electrode can be suppressed, and the capacity deterioration in the charge / discharge cycle can be suppressed. In order to leave the β phase of the Li—Al alloy in the negative electrode, the Li content should be about 3 atomic% or more when the total of Li and Al in the negative electrode is 100 atomic% at the end of discharge. What is necessary is just 5 atomic% or more. On the other hand, in order to increase the discharge capacity, the Li content at the end of the discharge is preferably 12 atomic% or less, and more preferably 10 atomic% or less.

  The Li content when the total of Li and Al in the negative electrode is 100 atomic% can be determined by, for example, inductively coupled plasma (ICP) elemental analysis. A battery having a negative electrode for determining the Li content is disassembled in an Ar box, and the negative electrode is taken out. The portion facing the positive electrode is cut into approximately 10 mm square and dissolved in acid, and this is subjected to elemental analysis by ICP. Thus, the ratio of Al to Li is obtained, and the content of Li is calculated from the value. Values shown in examples described later in this specification are values obtained by this method.

  In order to facilitate the realization of the use situation of the battery as described above, in the nonaqueous electrolyte battery of the present invention, in the negative electrode precursor used when forming the negative electrode by the first method, When the thickness of the Al layer is 100, the thickness of the Li layer to be bonded to the Al layer is preferably 10 or more, more preferably 20 or more, still more preferably 30 or more, 80 or less is preferable, and 70 or less is more preferable.

  The bonding of the Li foil and the Al layer related to the laminated metal foil can be performed by a conventional method such as pressure bonding.

  The negative electrode precursor used when forming the negative electrode by the first method is obtained by attaching a Li foil on the surface of the Al layer of the foil obtained by joining the Cu layer and the Al layer or the foil obtained by joining the Ni layer and the Al layer. It can be manufactured by a method of matching.

  The negative electrode precursor used in the first method and the second method for forming the negative electrode can be provided with a negative electrode lead body according to a conventional method. For example, when the base material layer of the laminated metal foil is exposed, it may be provided on the base material layer or directly on the Al layer.

  For the positive electrode according to the non-aqueous electrolyte battery of the present invention, for example, one having a structure in which a positive electrode mixture layer containing a positive electrode active material, a conductive additive, a binder and the like is provided on one side or both sides of a current collector can be used. . As the positive electrode active material, lithium-containing composite oxides (lithium-containing composite oxides capable of inserting and extracting Li ions) and positive electrode active materials other than lithium-containing composite oxides can be used. However, when the negative electrode is formed by the second method, a compound capable of releasing lithium such as a lithium-containing composite oxide is used as the positive electrode active material.

The lithium-containing composite oxide used as the positive electrode active material is represented by Li _{1 + x} M ¹ O ₂ (−0.1 <x <0.1, M ¹ : Co, Ni, Mn, Al, Mg, etc.). Layered lithium-containing composite oxide, LiMn ₂ O ₄ and spinel-structured lithium manganese oxide in which some of its elements are substituted with other elements, LiM ² PO ₄ (M ² : Co, Ni, Mn, Fe, etc. The olivine type compound etc. which are represented by this. Examples of the lithium-containing composite oxide having a layered structure include lithium cobalt oxide such as LiCoO ₂ and LiNi _1-a Co _ab Al _b O ₂ (0.1 ≦ a ≦ 0.3, 0.01 ≦ b ≦ 0. .2) and other oxides containing at least Co, Ni and Mn (LiMn _1/3 Ni _1/3 Co _1/3 O ₂ , LiMn _5/12 Ni _5/12 Co _1/6 O ₂ , LiNi _{3 / 5} Mn _1/5 Co _1/5 O ₂ etc.).

  Further, examples of the positive electrode active material other than the lithium-containing composite oxide include metal oxides such as manganese dioxide, vanadium pentoxide, and chromium oxide, and metal sulfides such as titanium disulfide and molybdenum disulfide. .

  As the positive electrode active material, only one of the above-exemplified compounds may be used, or two or more of them may be used in combination. However, the lithium-containing composite has a high capacity and excellent storage stability. It is preferable to use an oxide, and it is more preferable to use lithium cobaltate.

  Examples of the conductive auxiliary agent related to the positive electrode mixture layer include acetylene black; ketjen black; carbon blacks such as channel black, furnace black, lamp black, and thermal black; carbon materials such as carbon fibers; and metal fibers. Conductive fibers such as carbon fluoride, metal powders such as copper and nickel, organic conductive materials such as polyphenylene derivatives, and the like can be used.

  Examples of the binder related to the positive electrode mixture layer include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), styrene butadiene rubber (SBR), carboxymethyl cellulose (CMC), and polyvinylpyrrolidone (PVP).

  For the positive electrode, for example, a positive electrode mixture containing a positive electrode active material, a conductive additive and a binder is dispersed in a solvent (an organic solvent such as NMP or water) to form a positive electrode mixture-containing composition (paste, slurry, etc.). The positive electrode mixture-containing composition can be prepared, applied to one side or both sides of the current collector, dried, and subjected to a press treatment as necessary.

  Alternatively, a molded body may be formed using the positive electrode mixture, and a part or all of one side of the molded body may be bonded to the positive electrode current collector to form a positive electrode. Bonding of the positive electrode mixture molded body and the positive electrode current collector can be performed by press treatment or the like.

  As the current collector of the positive electrode, a metal foil such as Al or Al alloy, a punching metal, a net, an expanded metal, or the like can be used, but usually an Al foil is preferably used. The thickness of the positive electrode current collector is preferably 10 to 30 μm.

  The composition of the positive electrode mixture layer is, for example, 80.0 to 99.8% by mass of the positive electrode active material, 0.1 to 10% by mass of the conductive additive, and 0.1 to 10% by mass of the binder. It is preferable. Moreover, it is preferable that the thickness of a positive mix layer is 30-300 micrometers per single side | surface of a collector.

  The positive electrode current collector can be provided with a positive electrode lead body according to a conventional method.

  The capacity ratio of the positive electrode combined with the negative electrode may be set so that the Li content is 15 to 48 atomic% when the total of Li and Al in the negative electrode at the end of charging is 100 atomic%. It is desirable to set the capacity ratio of the positive electrode so that the β phase of the Li—Al alloy remains in the negative electrode at the end of discharge.

  In addition, before the assembly of the nonaqueous electrolyte battery, a negative electrode precursor in which no Li—Al alloy is generated is used. Therefore, when manufacturing a non-aqueous electrolyte battery, a battery is assembled using an electrode body precursor in which a positive electrode and a negative electrode precursor (laminated metal foil) are once formed through a separator, and the first method is performed inside an exterior body. Alternatively, a Li—Al alloy is produced by the second method to form a negative electrode, whereby the electrode body precursor is used as an electrode body.

  The separator preferably has a property of blocking its pores (that is, a shutdown function) at 80 ° C. or higher (more preferably 100 ° C. or higher) and 170 ° C. or lower (more preferably 150 ° C. or lower). A separator used in a water electrolyte secondary battery, for example, a microporous membrane made of polyolefin such as polyethylene (PE) or polypropylene (PP) can be used. The microporous film constituting the separator may be, for example, one using only PE or one using PP, or a laminate of a PE microporous film and a PP microporous film. There may be. The thickness of the separator is preferably 10 to 30 μm, for example.

  In the non-aqueous electrolyte battery of the present invention, for example, a flat electrode body precursor is loaded into the exterior body, and the non-aqueous electrolyte solution is further injected into the exterior body so that the electrode body is immersed in the non-aqueous electrolyte solution. Thereafter, the opening of the outer package is sealed, a Li—Al alloy is generated in the negative electrode precursor related to the electrode body precursor to form a negative electrode, and the electrode body precursor is used as an electrode body. As the exterior body, an exterior body made of steel, aluminum, aluminum alloy, an exterior body composed of a laminated film on which a metal is deposited, or the like can be used.

  As the non-aqueous electrolyte, a solution prepared by dissolving a lithium salt in the following non-aqueous solvent can be used.

  Examples of the solvent include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), γ-butyrolactone (γ-BL ), 1,2-dimethoxyethane (DME), tetrahydrofuran (THF), 2-methyltetrahydrofuran, dimethyl sulfoxide (DMSO), 1,3-dioxolane, formamide, dimethylformamide (DMF), dioxolane, acetonitrile, nitromethane, Methyl formate, methyl acetate, phosphoric acid triester, trimethoxymethane, dioxolane derivative, sulfolane, 3-methyl-2-oxazolidinone, propylene carbonate derivative, tetrahydrofuran derivative Aprotic organic solvents such as conductors, diethyl ether, and 1,3-propane sultone can be used alone or as a mixed solvent in which two or more are mixed.

The lithium salt according to the non-aqueous electrolyte solution, for _{example, LiClO 4, LiPF 6, LiBF} 4, LiAsF 6, LiSbF 6, LiCF 3 SO 3, LiCF 3 CO 2, Li 2 C 2 F 4 (SO 3) 2, At least selected from LiN (CF ₃ SO ₂ ) ₂ , LiC (CF ₃ SO ₂ ) ₃ , LiC _n F _{2n + 1} SO ₃ (n ≧ 2), LiN (RfOSO ₂ ) ₂ [where Rf is a fluoroalkyl group] One type is mentioned. The concentration of these lithium salts in the electrolytic solution is preferably 0.6 to 1.8 mol / l, and more preferably 0.9 to 1.6 mol / l.

  In addition, vinylene carbonates, 1,3-propane sultone, diphenyl disulfide, cyclohexylbenzene, biphenyl, fluorobenzene, t-butylbenzene, etc. are added to these nonaqueous electrolytes for the purpose of further improving various characteristics of the battery. An agent can also be added as appropriate.

  Furthermore, the non-aqueous electrolyte may be in the form of a gel (gel electrolyte) using a known gelling agent such as a polymer.

  Since the non-aqueous electrolyte battery of the present invention is configured with positive electrode capacity regulation, the charging end time can be detected by controlling the amount of charge and controlling the charging voltage. It is possible to set a charge termination condition in

  Therefore, in the nonaqueous electrolyte battery system having the nonaqueous electrolyte battery according to any one of the above aspects and a charging circuit, the total of Li and Al in the Al metal layer (A) is 100 atomic%. By setting the charge termination conditions such that the Li content is 15 to 48 atomic% at the end of charging, the storage characteristics of the nonaqueous electrolyte battery can be exhibited well.

  The non-aqueous electrolyte battery of the present invention can be preferably applied to applications that require good capacity maintenance over a long period of time in a high temperature environment, such as power supply applications for vehicle emergency notification systems.

  Hereinafter, the present invention will be described in detail based on examples. However, the following examples do not limit the present invention.

Example 1
A 15 μm thick Al foil (for Al metal layer (B)) is laminated on one side of a 25 μm thick Cu foil (tensile strength: 220 N / mm ² , volume resistivity: 2 × 10 ⁻⁶ Ω · cm). A clad material (laminated metal foil) having a size of 25 mm × 40 mm obtained by laminating an Al foil [for Al metal layer (A)] having a thickness of 20 μm on the other surface was used as a negative electrode precursor. Assembling the battery, the Cu foil for current collection is ultrasonically welded to the end of the clad material, and the Ni tab for conductive connection with the outside of the battery is ultrasonically welded to the end of the Cu foil. Used for.

On the other hand, the positive electrode was produced as follows. A slurry was prepared by dispersing 97 parts by mass of lithium cobaltate, 1.5 parts by mass of acetylene black as a conductive additive, and 1.5 parts by mass of PVDF as a binder in NMP, and this was thickened. A positive electrode material mixture layer having a mass of approximately 18 mg / cm ² was formed on each of both surfaces of the Al foil current collector by applying it to both surfaces of a 12 μm thick Al foil, drying, and pressing. In addition, the positive electrode mixture layer was not formed on a part of the current collector, and a portion where the Al foil was exposed was provided. Next, the Al foil current collector is cut into a size of 25 mm × 45 mm, and an Al tab for conductive connection with the outside of the battery is ultrasonically welded to a place where the Al foil is exposed, thereby collecting the current collector. A positive electrode having a positive electrode mixture layer having a size of 25 mm × 30 mm on both sides was prepared.

The negative electrode precursor was laminated on both sides of the positive electrode via a separator made of a microporous film made of PE having a thickness of 16 μm, and a pair of electrode body precursors was prepared. Further, a non-aqueous electrolyte was prepared by dissolving LiBF ₄ at a concentration of 1 mol / l in a mixed solvent of propylene carbonate (PC) and methyl ethyl carbonate (MEC) in a volume ratio of 1: 2. The electrode body precursor was dried in vacuum at 60 ° C. for 15 hours, and then encapsulated in a laminate film outer package together with the non-aqueous electrolyte. After 24 hours, constant current (6 mA) -constant voltage (4.0 V) charge is performed, and when the charge current drops to 0.3 mA, the charge is stopped and the battery is fully charged (the charge capacity at this time is charged for the first time). In this case, the Al metal layer on the side facing the positive electrode in the negative electrode precursor is formed, and a Li—Al alloy is formed on at least the surface facing the positive electrode to form the negative electrode as the Al metal layer (A). As a result, a non-aqueous electrolyte battery having the rated capacity of 30 mAh, the appearance shown in FIG. 1 and the cross-sectional structure shown in FIGS. 2 and 3 was prepared using the electrode body precursor as the electrode body.

  Here, FIG. 1, FIG. 2 and FIG. 3 will be described. FIG. 1 is a plan view schematically showing a nonaqueous electrolyte battery, FIG. 2 is a cross-sectional view taken along the line II of FIG. FIG. 3 is a partially enlarged view of FIG. 2. The nonaqueous electrolyte battery 1 includes a laminated electrode body formed by laminating a negative electrode 100 and a positive electrode 200 via a separator 300 in a laminated film outer package 700 constituted by two laminated films, and a nonaqueous electrolytic solution. (Not shown) is housed, and the laminate film outer package 700 is sealed by thermally fusing the upper and lower laminate films at the outer peripheral portion thereof. In FIG. 2, in order to avoid complication of the drawing, each layer constituting the laminate film outer package 700 and each layer of the negative electrode 100 and the positive electrode 200 are not shown separately. Each layer which comprises the film exterior body 700 is not distinguished and shown.

  The laminated electrode body accommodated in the laminate film outer package 700 of the battery 1 is composed of two negative electrodes 100 and 100 and one positive electrode 200. Each of the two negative electrodes 100 and 100 has only one surface facing the positive electrode 200, the Al metal layer (A) 102 is bonded to the surface of the metal base layer 101 on the positive electrode 200 side, and the other surface is made of Al. The metal layer (B) 103 is joined, and a Li—Al alloy is formed on at least the surface of the Al metal layer (A) 102 facing the positive electrode 200. The positive electrode 200 has positive electrode mixture layers 202 and 202 on both surfaces of the current collector 201.

  In the negative electrode 100 according to the non-aqueous electrolyte battery of Example 1, the thickness of the metal base layer 101 is 25 μm, and the thickness of the Al metal layer (B) 103 is 15 μm.

  The negative electrode 100 is connected to the negative electrode external terminal 104 in the battery 1 via a lead body. Although not shown, the positive electrode 200 is also connected to the positive electrode external terminal 204 in the battery 1 via a lead body. doing. The negative electrode external terminal 104 and the positive electrode external terminal 204 are drawn out to the outside of the laminate film exterior body 700 so that they can be connected to an external device or the like.

Example 2
A non-aqueous electrolyte was used in the same manner as in Example 1 except that a laminated metal foil having the same configuration as that of Example 1 was used as the negative electrode precursor except that the thickness of the Al foil for the Al metal layer (B) was changed to 20 μm. A battery was produced. In the negative electrode according to the nonaqueous electrolyte battery of Example 2, the thickness of the metal base layer is 25 μm, and the thickness of the Al metal layer (B) is 20 μm.

Example 3
A non-aqueous electrolyte was used in the same manner as in Example 1 except that a laminated metal foil having the same configuration as that of Example 1 was used as the negative electrode precursor except that the thickness of the Al foil for the Al metal layer (B) was changed to 30 μm. A battery was produced. In the negative electrode according to the nonaqueous electrolyte battery of Example 3, the thickness of the metal base layer is 25 μm, and the thickness of the Al metal layer (B) is 30 μm.

Example 4
A 25 μm thick Cu foil (tensile strength: 220 N / mm ² , volume resistivity: 2 × 10 ⁻⁶ Ω · cm) was laminated on both sides with a 20 μm thick Al foil (for Al metal layer (A)). A clad material (laminated metal foil) having a size of 25 mm × 40 mm was used as a negative electrode precursor for forming a negative electrode facing the positive electrode on both sides. Assembling the battery, the Cu foil for current collection is ultrasonically welded to the end of the clad material, and the Ni tab for conductive connection with the outside of the battery is ultrasonically welded to the end of the Cu foil. Used for.

  The same two negative electrode precursors used in Example 2, one negative electrode precursor having an Al foil for the Al metal layer (A) on both sides of the Cu foil, and the same as that prepared in Example 1. Using two positive electrodes, the same negative electrode precursor as used in Example 2 is the outermost layer, and each negative electrode precursor and each positive electrode are separated from the same separator as used in Example 1. And an electrode body precursor was formed by superimposing them. And it enclosed with the nonaqueous electrolyte solution in the laminate film exterior body like Example 1 except having used this electrode body precursor. After 24 hours, charging is performed with constant current (12 mA) -constant voltage (4.0 V), and when the charging current drops to 0.6 mA, the charging is stopped and the battery is fully charged (the charging capacity at this time is charged for the first time). In this case, the Al metal layer on the side facing the positive electrode in the negative electrode precursor is formed, and a Li—Al alloy is formed on at least the surface facing the positive electrode to form the negative electrode as the Al metal layer (A). A non-aqueous electrolyte battery with a rated capacity of 60 mAh was produced.

Comparative Example 1
A non-aqueous electrolyte was used in the same manner as in Example 1 except that a laminated metal foil having the same configuration as that of Example 1 was used as the negative electrode precursor except that the thickness of the Al foil for the Al metal layer (B) was changed to 50 μm. A battery was produced. In the negative electrode according to the nonaqueous electrolyte battery of Comparative Example 1, the thickness of the metal base layer 101 is 25 μm, and the thickness of the Al metal layer (B) 103 is 50 μm.

Comparative Example 2
A clad material (laminated metal foil) of 25 mm × 40 mm obtained by laminating an Al foil (for Al metal layer (A)) having a thickness of 20 μm on only one surface of a Cu foil having a thickness of 25 μm was used as a negative electrode precursor. A nonaqueous electrolyte battery was produced in the same manner as in Example 1 except for the above. In the negative electrode according to the nonaqueous electrolyte battery of Comparative Example 2, the thickness of the metal base layer 101 is 25 μm, and the Al metal layer (B) is not included.

Reference Example A laminated metal foil having the same configuration as that of Example 1 except that the thickness of the Al foil for the Al metal layer (B) was changed to 60 μm and the thickness of the Cu foil serving as the metal base layer was changed to 50 μm. Otherwise, a nonaqueous electrolyte battery was produced in the same manner as in Example 1. In the negative electrode according to the nonaqueous electrolyte battery of the reference example, the thickness of the metal substrate layer 101 is 50 μm, and the thickness of the Al metal layer (B) 103 is 60 μm.

  The following evaluations were made on the nonaqueous electrolyte batteries of Examples, Comparative Examples, and Reference Examples.

<Flatness of negative electrode and measurement of Li content>
Each non-aqueous electrolyte battery was charged at a constant current (0.2 C rate, ie, 12 mA for the battery of Example 4, 6 mA for the other batteries) -constant voltage (4.0 V), and the charging current was 0 The charge was stopped when the voltage dropped to the .01C rate (0.6 mA for the battery of Example 4, 0.3 mA for the other batteries), and the battery was fully charged and then decomposed in an argon gas atmosphere. The negative electrode was taken out and the degree of deformation was visually confirmed. In any negative electrode, the Li-Al alloy is formed in the portion facing the positive electrode mixture layer of the Al foil constituting the clad material, and the portion not facing the positive electrode mixture layer in the peripheral portion is It did not react with Li and existed as Al.

  In addition, when the battery was completely charged, the Li content was determined when the total amount of Li and Al in the Al metal layer (A) of the negative electrode was 100 atomic%.

<Charge / discharge cycle characteristics>
For each non-aqueous electrolyte battery, constant current (0.5 C rate, ie, 30 mA for the battery of Example 4, 15 mA for the other batteries) -constant voltage (4.0 V) charging (however, the charging current is 0 .05C rate, that is, when the battery of Example 4 was reduced to 3mA, and when other batteries were reduced to 1.5mA, charging was stopped at a current value of 1C rate (discharge capacity: rated) The charge / discharge cycle according to 40% of the capacity) was repeated. The charge / discharge cycle characteristics of each battery were evaluated based on the number of cycles until the battery voltage at the end of discharge was lower than 2V.

<Evaluation of charge / discharge efficiency>
For each non-aqueous electrolyte battery that was fully charged as described above after assembly, the 0.2C rate was continued within 10 minutes after being fully charged (12 mA for the battery of Example 4, and for other batteries). A constant current discharge of 6 mA was performed and terminated at 2 V. The ratio of the obtained discharge capacity to the initial charge / discharge capacity was defined as charge / discharge efficiency.

  These evaluation results are shown in Table 1 together with the structure of the negative electrode. In Table 1, in “Flatness of negative electrode”, the case where the deformation of the negative electrode was hardly recognized and the flatness was maintained was indicated by “◯”, and the case where the negative electrode was warped and the flatness was not maintained. Indicated by “x”. Further, “Li content of Al metal layer (A)” in Table 1 is the Li content when the total of Li and Al in the Al metal layer (A) of the negative electrode at the end of charging is 100 atomic%. Means content.

  As shown in Table 1, the non-aqueous electrolyte batteries of Examples 1 to 4 provided with a negative electrode having an Al metal layer (B) with an appropriate thickness, despite having a thin metal substrate layer, The deformation of the negative electrode was satisfactorily suppressed, and accordingly, the number of cycles during evaluation of charge / discharge cycle characteristics was large, and the charge / discharge cycle characteristics were excellent. Moreover, the nonaqueous electrolyte batteries of Examples 1 to 4 had high charge / discharge efficiency, and characteristic deterioration due to irreversible capacity was also suppressed.

  On the other hand, the battery of Comparative Example 1 including the negative electrode in which the Al metal layer (B) was too thick had low charge / discharge efficiency, and characteristic deterioration due to irreversible capacity occurred. In addition, the battery of Comparative Example 2 that does not have the Al metal layer (B) and includes the negative electrode having the Al metal layer (A) on one side is inferior in flatness of the negative electrode. The number of cycles at the time of characteristic evaluation was small, and charge / discharge cycle characteristics were also inferior.

  On the other hand, in the battery of the reference example provided with the negative electrode with a thick metal base layer, the flatness of the negative electrode was good. Moreover, although the negative electrode concerning the battery of a reference example does not produce the characteristic deterioration by an irreversible capacity | capacitance although the Al metal layer (B) is thick, this is because the metal base layer is thick, Since the distance between B) and the positive electrode is increased, the amount of Li that can reach the Al metal layer (B) is small when the Li-Al alloy is formed in the negative electrode precursor, and the Al metal layer (B) This is presumably because the formation of the Li—Al alloy did not proceed. From this result, it can be seen that the problem of coexistence of improving the flatness of the negative electrode and suppressing the decrease in charge and discharge efficiency in the present invention occurs when the metal base layer of the negative electrode is thin.

DESCRIPTION OF SYMBOLS 1 Nonaqueous electrolyte battery 100 Negative electrode 101 Metal base material layer 102 Al metal layer (A)
103 Al metal layer (B)
200 Positive electrode 201 Positive electrode current collector 202 Positive electrode mixture layer 300 Separator 700 Laminate film outer package

Claims (8)

A non-aqueous electrolyte battery having a flat electrode body in which a positive electrode and a negative electrode are stacked via a separator, and a non-aqueous electrolyte solution,
Only one side has a negative electrode facing the positive electrode,
The negative electrode whose one side only faces the positive electrode has a metal base layer not alloyed with Li, an Al metal layer (A) bonded to one side of the metal base layer, and the other side of the metal base layer. A laminated body containing a joined Al metal layer (B),
The Al metal layer (A) is disposed on the side facing the positive electrode, and at least a surface facing the positive electrode is formed with a Li-Al alloy,
The non-aqueous electrolyte battery characterized in that the metal substrate layer has a thickness of 35 μm or less, and the Al metal layer (B) has a thickness of 10 to 35 μm. The both sides further have a negative electrode facing the positive electrode,
The negative electrode whose both surfaces are opposed to the positive electrode is a laminate containing a metal base layer not alloyed with Li and an Al metal layer (A) bonded to each of both surfaces of the metal base layer,
2. The nonaqueous electrolyte battery according to claim 1, wherein a Li—Al alloy is formed on at least a surface of the Al metal layer (A) facing the positive electrode. 3.   Using a laminated metal foil formed by bonding an Al metal layer to both surfaces of a metal base layer not alloyed with Li, reacting at least the surface of the Al metal layer facing the positive electrode with Li, the negative electrode The nonaqueous electrolyte battery according to claim 1 or 2 formed.   4. The nonaqueous electrolyte battery according to claim 3, wherein the thickness of the Al metal layer is 30 to 180 when the thickness of the metal base layer not alloyed with Li is 100. 5.   The nonaqueous electrolyte battery according to any one of claims 1 to 4, wherein a joining portion between the Al metal layer (A) and the metal base material layer is made of Al that is not substantially alloyed with Li. .   The content of Li when the total of Li and Al is 100 atomic% in the Al metal layer (A) after completion of charging is 48 atomic% or less. Non-aqueous electrolyte battery.   The nonaqueous electrolyte battery according to any one of claims 1 to 6, wherein the metal base layer not alloyed with Li is made of Cu, Ni, or an alloy thereof. The non-aqueous electrolyte battery according to claim 1, wherein the positive electrode contains a lithium-containing composite oxide as a positive electrode active material.

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