JP2017195028A - Nonaqueous electrolyte battery, and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a nonaqueous electrolyte battery which can be charged repeatedly and which has good storage suitability under a high-temperature environment; and a method for manufacturing the nonaqueous electrolyte battery.SOLUTION: A nonaqueous electrolyte battery according to the present invention comprises: a flat plate like electrode body arranged by putting together positive and negative electrodes with a separator interposed therebetween; and a nonaqueous electrolyte solution. The negative electrode is composed of a laminate including a metal base layer of a metal unalloyable with Li, and an Al active layer joined to the base layer of the metal, in which a Li-Al alloy is produced at least on the side of a face of the Al active layer opposed to the positive electrode. The Al active layer in the laminate is formed by the Li-Al alloy production at least on the side of the face of the Al metal layer of a piece of laminate metal foil opposed to the positive electrode, provided that the piece of laminate metal foil is arranged by joining the Al metal layer to the metal base layer of the metal unalloyable with Li and is 35 (Hv) or more in Vickers hardness measured on the side of the Al metal layer.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a nonaqueous electrolyte battery having good storage characteristics and a method for producing the same.

  Non-aqueous electrolyte batteries are used for various applications by taking advantage of characteristics such as high capacity and high voltage. Particularly in recent years, with the commercialization of electric vehicles, demand for non-aqueous electrolyte batteries for in-vehicle use has increased.

  As the in-vehicle use of the nonaqueous electrolyte battery, the application is mainly to the drive power source of the motor of the electric vehicle, but the application to other than that is also being promoted. For example, the development of an emergency call system is currently underway to notify the relevant places when a vehicle encounters an accident. However, the application of non-aqueous electrolyte batteries is being considered as the power source. Yes.

  Such a system is required to operate reliably in an emergency, although the opportunity to actually operate is limited. For this reason, a battery serving as a power source is required to have a reliability capable of maintaining its characteristics well even when stored for a long period of time. Therefore, for such applications, non-aqueous electrolysis has better storage characteristics than non-aqueous electrolyte secondary batteries, which are widely used as power sources for electronic devices, and has almost no decrease in capacity even when stored for a long period of several years or longer. Liquid primary batteries are used.

  As the negative electrode active material of the non-aqueous electrolyte primary battery, metallic lithium or a lithium alloy such as a Li—Al (lithium-aluminum) alloy is used. For example, as described in Patent Document 1, Also in the nonaqueous electrolyte secondary battery, a lithium alloy can be used as the negative electrode active material.

  Patent Document 1 proposes a technique of using a specific Vickers hardness as the aluminum used for Li-Al alloying in a Li-Al alloy negative electrode, whereby a lithium secondary battery (non-aqueous) is proposed. It is possible to prevent warping of the negative electrode accompanying charge / discharge of the electrolyte secondary battery.

  Patent Document 2 discloses an organic material having a Li-Al alloy in a negative electrode by forming a negative electrode using a clad material of a metal capable of occluding and releasing lithium and a heterogeneous metal not capable of occluding and releasing lithium. It has also been proposed to stabilize the characteristics of the electrolyte secondary battery.

  On the other hand, even in applications such as the power supply for the emergency call system, there are cases where a battery that can be repeatedly charged is required due to various circumstances, for example, even if the cladding material as described above is used, It is not always possible to stabilize the characteristics of the non-aqueous electrolyte secondary battery.

  On the other hand, Patent Document 3 is a clad material of a metal capable of occluding and releasing lithium and a dissimilar metal not capable of occluding and releasing lithium, and using a different kind of metal as the dissimilar metal, Non-aqueous electrolyte battery (non-aqueous electrolyte secondary battery) that has achieved stabilization of characteristics by using a clad material having a metal layer capable of inserting and extracting lithium on both sides of the metal layer ) Has been proposed.

JP-A-7-320723 JP-A-8-293302 International Publication No. 2016/039323

  The technique described in Patent Document 3 is effective for improving the characteristics of a non-aqueous electrolyte battery that can be repeatedly charged. However, applications that are likely to be placed at high temperatures such as in-vehicle applications will continue to be used in the future. Under the assumption of further increase, it can be said that the development of technology for enhancing the high-temperature storage characteristics of non-aqueous electrolyte batteries is still important.

  The present invention has been made in view of the above circumstances, and its purpose is to provide a nonaqueous electrolyte battery that can be repeatedly charged and has good storage characteristics in a high-temperature environment, and a method for producing the same. It is to provide.

  The non-aqueous electrolyte battery of the present invention that has achieved the above object has a plate-like electrode body in which a positive electrode and a negative electrode are stacked with a separator interposed therebetween, and a non-aqueous electrolyte. , A laminate comprising a metal base layer not alloyed with Li and an Al active layer bonded to the metal base layer, and at least the surface of the Al active layer facing the positive electrode is Li- An Al alloy is formed, and the Al active layer in the laminate has a Vickers hardness measured on the Al metal layer side, in which an Al metal layer is bonded to a metal base layer that is not alloyed with Li Is formed by forming a Li—Al alloy on at least the surface of the Al metal layer facing the positive electrode of the laminated metal foil of 35 (Hv) or more.

  The method for producing a non-aqueous electrolyte battery of the present invention is a method for producing a non-aqueous electrolyte battery having 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 solution. In this case, the Al metal layer side of the laminated metal foil obtained by bonding an Al metal layer to a metal base layer that is not alloyed with Li and the positive electrode are opposed to each other with a separator interposed therebetween, so that a flat electrode precursor is obtained. Forming a body, housing the electrode body precursor and the non-aqueous electrolyte in an outer package, and forming Li-Al on at least the surface of the Al metal layer of the laminated metal foil facing the positive electrode Forming an anode by forming an alloy, and using the electrode body precursor as the electrode body, and as the laminated metal foil, an Al metal layer sheet and a metal that does not alloy with Li After annealing the pressure contact material that is pressure contacted with the base material layer sheet By cold working, characterized in that it uses a foil having an adjusted Vickers Hardness measured in the Al metal layer side 35 (Hv) or more.

  According to the present invention, it is possible to provide a non-aqueous electrolyte battery that can be repeatedly charged and has good storage characteristics in a high-temperature environment, and a manufacturing method thereof.

It is sectional drawing which represents typically an example of the negative electrode (negative electrode precursor) used for the nonaqueous electrolyte battery of this invention. 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.

  Li (metal Li) and Li—Al alloys (alloys of Li and Al) have lower acceptability of Li (Li ions) than carbon materials, and non-aqueous electrolytes using this as a negative electrode active material In the secondary battery, when charging and discharging are repeated, the capacity tends to decrease at an early stage. For these reasons, carbon materials such as graphite are widely used as negative electrode active materials in non-aqueous electrolyte secondary batteries that are expected to be repeatedly charged and discharged.

  On the other hand, in a non-aqueous electrolyte secondary battery using a carbon material as a negative electrode active material, self-discharge is likely to occur, and the capacity is likely to decrease when stored in a charged state.

  For this reason, although there are limited opportunities for actual operation, such as a vehicle emergency call system, a battery for a power source of a device that is required to operate reliably when necessary is used as a non-aqueous electrolyte. Non-aqueous electrolyte primary batteries have been applied that have better storage characteristics than secondary batteries and have little capacity reduction even when stored for a long period of several years or longer.

  On the other hand, even in such applications, for reasons such as ease of maintenance, charging does not require repeated charging and discharging as many times as in ordinary secondary batteries, but charging can be performed several times to several tens of times. There is a request for application of possible batteries.

  Therefore, the non-aqueous electrolyte battery of the present invention can realize high storage characteristics and high capacity even when used in a high temperature environment such as in-vehicle use, and a certain number of times. Li-Al alloy was used as the negative electrode active material so that charging was possible.

  In the nonaqueous electrolyte battery of the present invention, in order to enhance the storage characteristics, a current collector is used for the purpose of stabilizing the shape of the negative electrode during discharge and enabling the next charge.

  In a battery using a Li—Al alloy as the negative electrode active material, a Li foil (including a Li alloy foil unless otherwise specified; the same shall apply hereinafter) and an Al foil (including an Al alloy foil unless otherwise specified); Are bonded together and introduced into the battery, and Li and Al are reacted in the presence of a non-aqueous electrolyte to form a Li—Al alloy. However, when a metal foil (Cu (copper) foil, Cu alloy foil, etc.) to be a current collector is inserted into the battery simply by being stacked on a laminate of Li foil and Al foil, after storage (particularly high temperature) The internal resistance of the battery increases after storage in the environment, and the storage characteristics are not sufficiently improved.

  This is because, in the battery, the volume change occurs when the Li—Al alloy is formed by the laminate of the Li foil and the Al foil, or the Li—Al alloy is formed and pulverization occurs, so that the negative electrode is not It has been clarified that this is because it becomes difficult to absorb the water electrolyte solution and a volume change occurs, so that the adhesion between the Li-Al alloy layer (Al foil) and the current collector cannot be secured.

  Therefore, in the present invention, an Al metal layer (Al foil or the like) for forming a Li—Al alloy and a metal base layer (Cu foil or the like) that is not alloyed with Li acting as a current collector are bonded in advance. In addition, a method of laminating a Li layer (Li foil or the like) on the surface of the metal layer and reacting Li of the Li layer and Al of the Al metal layer, or the Al metal layer and the metal substrate The assembly of the Al metal layer is used as it is for assembling the battery, and the Al metal layer is subjected to electrochemical reaction with Li ions in the non-aqueous electrolyte by charging after assembly. At least the surface side is made of a Li—Al alloy, and the negative electrode in which an Al active layer is bonded to the surface of the metal base material layer makes it possible to suppress an increase in internal resistance during storage.

  Further, a laminated metal foil for forming a negative electrode, that is, a laminated metal foil having a metal base layer and an Al metal layer bonded to the metal base layer, is subjected to Vickers hardness measured on the Al metal layer side. Using a foil whose thickness is adjusted to a specific value or more and forming an Li-Al alloy on at least the surface of the Al metal layer facing the positive electrode, an Al active layer is bonded to the surface of the metal substrate layer. In the case of the negative electrode having the laminated body, the reason is not clear, but it has been found that the discharge characteristics after storing the battery at a high temperature can be maintained better.

  In Patent Document 1, by setting the Vickers hardness of aluminum used in the negative electrode having a Li—Al alloy within a specific range, the warpage of the negative electrode at the time of forming the Li—Al alloy is not increased so much. It has been pointed out that good charge / discharge characteristics can be secured by preventing the warpage of the negative electrode that may occur during charging.

  However, in the present invention, the metal base layer of the negative electrode is composed of a specific type of metal, or the metal base layer is formed by using a laminated metal foil in which an Al metal layer is bonded to both sides of the metal base layer. Vickers hardness measured on the Al metal layer side even when adopting a configuration that suppresses warpage of the negative electrode that may occur during battery charging (details will be described later), such as a negative electrode with an Al active layer bonded on both sides. When the laminated metal foil whose thickness is adjusted to a specific value or more is used and when the laminated metal foil whose Vickers hardness does not satisfy the specific value is used, a difference occurs in the high-temperature storage characteristics of the battery, the former Has been confirmed to exhibit better high-temperature storage characteristics (this will be described in the examples below). Therefore, it is presumed that the mechanism that achieves the above effect in the present invention is completely different from the mechanism pointed out in Patent Document 1.

  The laminated metal foil used for forming the negative electrode is one in which an Al metal layer is bonded to one side or both sides of an Al base layer (for example, a clad material).

  The laminated metal foil is a foil having a Vickers hardness of 35 (Hv) or more measured on the Al metal layer side, more specifically, an Al metal layer sheet and a metal substrate layer that is not alloyed with Li. The foil which adjusted the Vickers hardness measured by the said Al metal layer side to 35 (Hv) or more by carrying out cold processing after carrying out the diffusion annealing (for example, about 150-550 degreeC) the pressure welding material which pressure-contacted the sheet | seat for water (Clad material) is used.

  In the production of a normal clad material, a method is adopted in which two or more kinds of metal sheets are stacked and pressure-welded (rolled), and the obtained pressure-welded material is diffusion-annealed and then cold-worked and thinned. Here, when the obtained clad material can suppress warping of the electrode due to charge and discharge, when forming a flat electrode body in which the positive electrode and the negative electrode are stacked via the separator, In order to further improve the adhesion to the separator, it is preferable that the flexibility is high. In order to meet such demands, in the production of the clad material, it is generally performed to further perform a heat treatment after the cold working. Therefore, the clad material obtained by such a manufacturing method is usually soft, and in the case of a clad material obtained by using an Al metal sheet as one of the metal sheets, measurement is made on the Al metal layer side derived from the Al metal sheet. The Vickers hardness is lower than 35 (Hv).

  However, the laminated metal foil manufactured so that the Vickers hardness measured on the Al metal layer side is 35 (Hv) or more by using no heat treatment after cold working was used for forming the negative electrode. In this case, as described above, the reason is not clear, but the high-temperature storage characteristics of the battery are improved.

  The laminated metal foil used for forming the negative electrode may have a Vickers hardness measured on the Al metal layer side of 35 (Hv) or higher, preferably 37 (Hv) or higher, and 90 (Hv). ) Or less, more preferably 50 (Hv) or less. That is, in the laminated metal foil obtained by the manufacturing method, the Vickers hardness measured on the Al metal layer side is 35 (Hv) or more [preferably 37 (Hv) or more and 90 (Hv) or less]. As long as it is manufactured by selecting the manufacturing conditions.

  The Vickers hardness of the laminated metal foil referred to in this specification is a value measured in accordance with JIS Z 2244 on the Al metal layer side of the laminated metal foil. In addition, in the case of the laminated metal foil in which the Al metal layer is bonded to both surfaces of the metal base layer, the Vickers hardness of either one of the two Al metal layers, if manufactured by the above-described manufacturing method When the value satisfies the specific value, the other Vickers hardness also satisfies the specific value.

  In the nonaqueous electrolyte battery of the present invention, a laminated metal foil satisfying the Vickers hardness is used, and an Al active layer is formed on at least the surface of the Al metal layer to form an Al active layer, thereby forming a negative electrode. . In order to generate the Li—Al alloy in the Al metal layer, any of the following first and second methods may be employed.

  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 laminated body 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 bonding an Al layer) 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 sufficiently suppress the expansion of the negative electrode during charging (and the deformation of the negative electrode such as warping associated therewith) even if the material layer is thinned, the base material layer is selected from nickel, titanium and iron What is necessary is just to comprise with a material with high tensile strength like a metal or its alloy, and it is preferable to comprise with the material whose tensile strength in room temperature is 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 For example, the battery characteristic deterioration caused by deformation of the negative electrode such as warpage caused by expansion of the negative electrode is increased. 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. the thin also has the advantages of excellent expansion inhibition (deformation suppressing effect of the negative electrode) and, in particular, (if there are multiple, the total area) area of Al active layer when a becomes 10 cm ² or more 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.

  FIG. 1 is a cross-sectional view schematically showing an example of a laminate (negative electrode precursor) for forming a negative electrode used in the nonaqueous electrolyte battery of the present invention. In the negative electrode precursor 100 of FIG. 1, Li foils 102 and 102 are bonded to the surfaces of Al layers 101b and 101b of a laminated metal foil 101 formed by bonding Al layers 101b and 101b to both surfaces of a base material layer 101a. It is the laminated body formed in this way.

  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 formed on the surface (separator side) and changes to an Al active layer. That is, at least the surface side (Li foil side) of the Al active layer of the negative electrode has a Li—Al alloy formed in the nonaqueous electrolyte battery.

  In the negative electrode precursor, in the laminated metal foil formed by joining the base material layer and the Al layer, the Al layer may be joined to one side of the base material layer, and as shown in FIG. Al layers may be bonded to both sides of the substrate. In addition, when using a laminated metal foil with Al layers bonded to both sides of the base material layer, even if the negative electrode expands as the battery is charged, the occurrence of deformation such as warping of the negative electrode can be suppressed. Therefore, battery characteristics such as charge / discharge cycle characteristics are further improved.

  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 10 or more, more preferably 20 or more, still more preferably 50 or more, and particularly 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.

  In addition, it is preferable that the thickness of Cu layer and Ni layer which is a base material layer is 10-50 micrometers, and it is more preferable that it is 40 micrometers or less. Further, 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), the thickness per side is preferably 10 μm or more, and is 20 μm or more. More preferably, it is 30 μm or more, particularly preferably 150 μm or less, more preferably 70 μm or less, and particularly preferably 50 μm or less.

  The thickness of 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 is 50 μm or more in order to make the capacity of the negative electrode constant or more. It is preferably 60 μm or more, and is preferably 300 μm or less, more preferably 200 μm or less, and more preferably 150 μm or less so that the capacity ratio with the positive electrode active material is within an appropriate range. It is particularly preferred that

  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 Al active layer of the negative electrode by using the laminate formed by bonding the Li foil to the surface of the laminated metal foil as the negative electrode precursor, the second method is the laminated metal foil. The Al active layer constituting the negative electrode can also be formed by a method of assembling a battery using as a negative electrode precursor as it is and charging the assembled battery.

  That is, at least the surface side Al of the Al metal layer of the laminated metal foil is electrochemically reacted with Li ions in the non-aqueous electrolyte by charging the battery, thereby generating a Li-Al alloy at least on the surface side. It is also possible to use an Al active layer.

  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 active layer 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. It is preferable to form a negative electrode by the first method (form an Al active layer of the negative electrode). Also, a battery is assembled using the negative electrode precursor according to the first method, and further charged to form a negative electrode ( (Al active layer of negative electrode may be formed).

  In a battery having, as a non-aqueous electrolyte battery of the present invention, a negative electrode including a laminate including a metal base layer not alloyed with Li and an Al active layer bonded to the metal base layer, the negative electrode From the viewpoint of maintaining a good crystal structure of the substance acting as the active material and stabilizing the potential of the negative electrode to ensure better storage characteristics, the negative electrode is formed by any one of the first method and the second method. Even when the Al active layer is formed, the battery is used in a range where the Li content is 48 atomic% or less when the total of Li and Al in the Al active layer of the negative electrode is 100 atomic%. It is preferable. That is, when charging the battery, it is preferable to terminate the charging in a range where the Li content of the Al active layer does not exceed 48 atomic%, and the charging is terminated in a range where the Li content is 40 atomic% or less. More preferably, it is particularly preferable to terminate the charging in 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 layer is not alloyed with Li on the base layer side of the Al layer, and the Al active layer is placed on the surface side. It is more preferable to have a laminated structure of the Li—Al alloy layer and the Al layer remaining on the substrate 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 Al layer in the vicinity of the joint with the base material layer is presumed to remain as the original Al layer without reacting with Li substantially, 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. It is preferable to charge the battery to such a range, and it is more preferable to charge the battery to a range of 20 atomic% or more.

  Furthermore, it is desirable that the negative electrode according to the non-aqueous electrolyte battery of the present invention terminates the discharge in the state where the Al metal phase (α phase) and the Li—Al alloy phase (β phase) coexist. It is possible to suppress the volume change of the negative electrode during discharge and suppress capacity deterioration in the charge / discharge cycle. 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 specific thickness of the Li foil (when the laminate has Li foil on both sides, the thickness per side) is preferably 10 μm or more, more preferably 20 μm or more, and 30 μm. More preferably, it is 80 μm or less, and more preferably 70 μm or less.

  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 laminate used as the negative electrode precursor used when forming the negative electrode by the first method is formed 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 bonding Li foil.

  A negative electrode lead body can be provided on the Cu layer and the Ni layer in the laminate used as the negative electrode precursor used in the first method and the second method for forming the negative electrode according to a conventional method.

  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 the non-aqueous electrolyte battery according to the present invention, the positive electrode and the negative electrode are stacked in a flat plate shape with the separator interposed therebetween (they are stacked substantially in parallel to the plane of the electrode and the separator without being wound). A laminated electrode body having a structure having at least one of a positive electrode and a negative electrode, and a case where a plurality of positive electrodes and a plurality of negative electrodes are alternately laminated) Is done. However, before the battery is assembled, 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.

  The non-aqueous electrolyte battery of the present invention, for example, is loaded with a plate-shaped electrode body precursor in the exterior body, injecting the non-aqueous electrolyte solution into the exterior body, and immersing the electrode body precursor in the non-aqueous electrolyte solution Then, the opening of the outer package is sealed, and 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 the 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 content of Li when the total of Li and Al in the Al active layer is 100 atomic% By setting the charge termination condition such that the amount is 15 to 48 atomic% at the end of the charge, the storage characteristics of the nonaqueous electrolyte battery can be exhibited well.

  Since the non-aqueous electrolyte battery of the present invention can be repeatedly charged and has good storage characteristics in a high temperature environment, taking advantage of these characteristics, as in the power supply application of a vehicle emergency notification system, 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.

  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 clad material (laminated metal foil) obtained by arranging and rolling an Al metal sheet for an Al layer on both surfaces of a Ni sheet for a base material layer (Ni layer), rolling and annealing, and then cold-working 25 mm × It cut | disconnected to the size of 40 mm and used as a negative electrode precursor. No heat treatment was performed after the cold working at the time of manufacturing the clad material, and the Vickers hardness measured on the Al layer side was 40 (Hv). Further, the thickness of the Ni layer and the thickness of both Al layers in the clad material were both 30 μm.

  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 23 mg / cm ² was formed on one surface of the Al foil current collector by applying it to one surface of a 12 μm thick Al foil, drying it, and pressing it. In addition, the positive electrode mixture layer was not formed on a part of the application surface of the slurry, and a portion where the Al foil was exposed was provided. Next, the Al foil current collector is cut into a size of 20 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 with a size of 20 mm × 30 mm on one side was prepared.

The positive electrodes were laminated on both sides of the negative electrode precursor to which the Ni tab was welded via a separator made of a microporous film made of PE having a thickness of 16 μm, thereby preparing a pair of electrode body precursors. 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. 24 hours later, constant-current (6 mA) -constant-voltage (4.0 V) charging is performed. When the charging current is reduced to 0.3 mA, charging is terminated, and the battery is fully charged, whereby the positive electrode in the negative electrode precursor The negative electrode is formed as an Al active layer by forming a Li-Al alloy on at least the surface facing the positive electrode, thereby forming a negative electrode as an electrode body precursor. Was 30 mAh, had the appearance shown in FIG. 2, and produced a non-aqueous electrolyte battery having a cross-sectional structure shown in FIG.

  Here, FIG. 2 and FIG. 3 will be described. FIG. 2 is a plan view schematically showing a nonaqueous electrolyte battery, and FIG. 3 is a cross-sectional view taken along the line II of FIG. The nonaqueous electrolyte battery 1 includes a laminated electrode body formed by laminating a positive electrode 200 and a negative electrode 100 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. Note that, in FIG. 3, in order to avoid the drawing from being complicated, each layer constituting the laminate film exterior body 700 and each layer of the positive electrode 200 and the negative electrode 100 are not distinguished.

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

Comparative Example 1
Example 1 except that the clad material used as the negative electrode precursor (laminated metal foil with Al layers bonded to both sides of the Ni layer) was changed to one obtained by a manufacturing method in which heat treatment was performed after cold working Thus, a non-aqueous electrolyte battery was produced. The clad material had a Vickers hardness of 29 (Hv) measured on the Al layer side.

  The nonaqueous electrolyte batteries of Example 1 and Comparative Example 1 were allowed to stand for 24 hours after assembly, and then subjected to the following high-temperature storage characteristics evaluation.

<High temperature storage characteristics evaluation>
About each battery of Example 1 and Comparative Example 1, constant current (6 mA) -constant voltage (4.0 V) charging was performed, and charging was terminated when the charging current decreased to 0.3 mA. Next, the battery was discharged at a constant current of 6 mA (discharge end voltage: 2 V) to measure the discharge capacity (initial discharge capacity), and further charged under the above charging conditions to make the battery fully charged. All batteries had an initial discharge capacity of 30 mAh.

  Each battery in a fully charged state was stored at 85 ° C. for 11 days, cooled to room temperature, discharged at a constant current of 6 mA (discharge end voltage: 2 V), and the remaining capacity was measured. Further, charging under the above charging conditions and discharging at 90 mA (discharge end voltage: 2 V) were performed, and the discharge capacity (recovery capacity) after high temperature storage was measured. The high-temperature storage characteristics of each battery were evaluated by the ratio of the remaining capacity and the recovery capacity (capacity maintenance ratio) to the initial discharge capacity.

  The evaluation results are shown in Table 1.

  As shown in Table 1, the non-aqueous electrolyte battery of Example 1 having a negative electrode formed of a laminated metal foil having more preferable properties was compared with the battery of Comparative Example 1, and the remaining capacity at the time of high-temperature storage property evaluation and The retention rate of the recovery capacity was high and it had excellent high-temperature storage characteristics.

  The nonaqueous electrolyte batteries of Example 1 and Comparative Example 1 (batteries different from those subjected to high temperature storage characteristics evaluation) were allowed to stand for 24 hours after assembly, and then constant current (6 mA) -constant voltage (4 .0V) charge, and when the charge current drops to 0.3 mA, the charge is stopped, the battery is fully charged, then decomposed in an argon gas atmosphere, the negative electrode is taken out, and the degree of deformation is visually confirmed. did. As a result, for any negative electrode, the Li-Al alloy is formed in the portion facing the positive electrode mixture layer of the Al foil constituting the cladding material, and the portion not facing the positive electrode mixture layer in the peripheral portion is , Li did not react and existed as Al.

  In addition, when the battery was completely charged, the Li content was 31 atomic% when the total of Li and Al in the Al active layer of the negative electrode was 100 atomic%.

  Further, in the negative electrode taken out from any of the batteries, almost no bending (warping) of the negative electrode due to the formation of the Al active layer was observed, and the flatness was almost maintained. Therefore, the difference in the high-temperature storage characteristics observed between the non-aqueous electrolyte battery of Example 1 and the battery of Comparative Example 1 is different from prevention of warping of the negative electrode that may occur due to battery charging. It was found to be caused by the mechanism.

Example 2
An Al metal sheet for an Al layer is placed on both sides of a Cu sheet for a base material layer (Cu layer), rolled, annealed and then cold-worked, and then a clad material (laminated metal foil) obtained as a negative electrode precursor A nonaqueous electrolyte battery was produced in the same manner as in Example 1 except that the above was used. Note that heat treatment was not performed after the cold working in the production of the clad material, and the Vickers hardness measured on the Al layer side was 43 (Hv). Further, the thickness of the Cu layer and the thickness of both Al layers in the clad material were both 30 μm.

Comparative Example 2
The same as in Example 2 except that the clad material (laminated metal foil with Al layers bonded to both sides of the Cu layer) used as the negative electrode precursor was changed to one obtained by a manufacturing method in which heat treatment was performed after cold working Thus, a non-aqueous electrolyte battery was produced. The clad material had a Vickers hardness of 32 (Hv) measured on the Al layer side.

  About the nonaqueous electrolyte battery of Example 2 and Comparative Example 2, high temperature storage characteristic evaluation was performed by the same method as the battery of Example 1 and the like. The results are shown in Table 2.

  As shown in Table 2, the non-aqueous electrolyte battery of Example 2 having a negative electrode formed of a laminated metal foil having more preferable properties was compared with the battery of Comparative Example 2, and the remaining capacity at the time of high-temperature storage property evaluation and The retention rate of the recovery capacity was high and it had excellent high-temperature storage characteristics.

  Note that the non-aqueous electrolyte batteries of Example 2 and Comparative Example 2 (batteries different from those subjected to high temperature storage characteristics evaluation) were allowed to stand for 24 hours after assembly, and then were subjected to constant current (6 mA) -constant voltage (4 .0V) charge, and when the charge current drops to 0.3 mA, the charge is stopped, the battery is fully charged, then decomposed in an argon gas atmosphere, the negative electrode is taken out, and the degree of deformation is visually confirmed. did. As a result, for any negative electrode, the Li-Al alloy is formed in the portion facing the positive electrode mixture layer of the Al foil constituting the cladding material, and the portion not facing the positive electrode mixture layer in the peripheral portion is , Li did not react and existed as Al.

  In addition, when the battery was completely charged, the Li content was 31 atomic% when the total of Li and Al in the Al active layer of the negative electrode was 100 atomic%.

  Further, in the negative electrode taken out from any of the batteries, almost no bending (warping) of the negative electrode due to the formation of the Al active layer was observed, and the flatness was almost maintained. Therefore, the difference in the high-temperature storage characteristics observed between the nonaqueous electrolyte battery of Example 2 and the battery of Comparative Example 2 is also recognized between the battery of Example 1 and the battery of Comparative Example 1. Similar to the difference in the high temperature storage characteristics obtained, it has been found that this is caused by a mechanism different from the prevention of the warpage of the negative electrode that may occur due to the charging of the battery.

1 Nonaqueous electrolyte battery 100 Negative electrode, negative electrode precursor (negative electrode laminate)
101 Laminated Metal Foil 101a Metal Base Layer 101b Al Metal Layer 102 Li Foil 103 Al Active Layer 200 Positive Electrode 300 Separator 700 Laminate Film Outer Body

Claims (6)

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,
The negative electrode is a laminate including a metal base layer that is not alloyed with Li and an Al active layer bonded to the metal base layer, and at least on the side of the Al active layer facing the positive electrode Li-Al alloy is produced,
The Al active layer in the laminate is a laminate in which an Al metal layer is bonded to a metal base layer that is not alloyed with Li, and a Vickers hardness measured on the Al metal layer side is 35 (Hv) or more. A non-aqueous electrolyte battery characterized in that a Li-Al alloy is formed at least on the surface of the metal foil facing the positive electrode of the Al metal layer.   The non-aqueous electrolyte battery according to claim 1, wherein the laminated metal foil is a clad material.   The non-aqueous electrolyte battery according to claim 1, wherein the Li—Al alloy is generated by charging.   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. A method for producing a non-aqueous electrolyte battery comprising 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 solution,
A planar electrode body precursor is formed by facing the Al metal layer side of the laminated metal foil obtained by bonding an Al metal layer to a metal base layer not alloyed with Li and a positive electrode with a separator interposed therebetween. Process,
Storing the electrode body precursor and the non-aqueous electrolyte in an exterior body;
Forming a negative electrode by forming a Li-Al alloy on at least the surface of the Al metal layer of the laminated metal foil facing the positive electrode, thereby forming the electrode body precursor as the electrode body. And
As the laminated metal foil, Vickers measured on the Al metal layer side by cold working after annealing a pressure contact material in which a sheet for Al metal layer and a sheet for metal base layer not alloyed with Li are welded A method for producing a non-aqueous electrolyte battery, comprising using a foil having a hardness adjusted to 35 (Hv) or more. The method for producing a non-aqueous electrolyte battery according to claim 5, wherein the Li—Al alloy is generated by charging.

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