JP2019129145A - Nonaqueous electrolyte battery - Google Patents

Abstract

To provide a nonaqueous electrolyte battery which can be charged repeatedly, which has a good storage characteristic under a high-temperature environment, and which is superior in reliability.SOLUTION: A nonaqueous electrolyte battery according to the present invention comprises: an electrode body in which a negative electrode containing at least one negative electrode active material selected from a group consisting of lithium, a lithium alloy, an element alloyable with lithium, and a compound including the element is superposed on a positive electrode through a separator; and a nonaqueous electrolyte. The separator has a porous film (I) including a thermoplastic resin as a primary component and a porous film (II) including an acerate filler of which the heatproof temperature is 150°C or above as a primary component.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a non-aqueous electrolyte battery capable of repeated charge and discharge and having excellent storage characteristics and low temperature discharge characteristics and excellent reliability.

  Nonaqueous electrolyte batteries are utilized in various applications by taking advantage of properties such as high capacity and high voltage. In particular, with the commercialization of electric vehicles in recent years, the demand for non-aqueous electrolyte batteries for vehicles has increased.

  As the in-vehicle use of the non-aqueous 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, when a vehicle encounters an accident, etc., an emergency call system is currently under development to notify the relevant parties of the accident, but the application of a non-aqueous electrolyte battery is being considered as the power source. .

  Such systems are required to operate reliably in an emergency, although they have limited opportunities to operate in practice. 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 electrolyte primary batteries that have better storage characteristics than non-aqueous electrolyte secondary batteries that are widely used as power sources for electronic devices, and that have little capacity loss even when stored for several years or longer Batteries are being used.

  As a negative electrode active material of the non-aqueous electrolyte primary battery, a lithium alloy such as Li (metallic lithium) or Li-Al (lithium-aluminum) alloy is used, but in the non-aqueous electrolyte secondary battery as well, the negative electrode Since lithium alloy can be used as the active material, the battery characteristics are stabilized by forming the negative electrode using a clad material of a metal capable of storing and releasing lithium and a different metal having no capacity of storing and releasing lithium. Has also been proposed (Patent Documents 1 and 2). Furthermore, the negative electrode containing at least one negative electrode active material selected from the group consisting of Li, a Li alloy, an element capable of alloying with Li, and a compound containing the element, and a phosphoric acid compound as a non-aqueous electrolyte A non-aqueous electrolyte battery (Patent Document 3) or a negative electrode containing a Li-Al alloy, which is contained in a range of 8% by mass or less, and a non-aqueous electrolyte battery containing an imide-based binder or an amide-based binder as a binder for the positive electrode (Patent Document 4).

  On the other hand, in order to suppress an internal short circuit due to the shrinkage of the separator when the battery is exposed to a high temperature, various separators having high heat resistance have been proposed. A separator laminated on a membrane has been proposed. According to this separator, the charge and discharge characteristics at a high rate are improved.

JP-A-8-293302 International Publication WO2016 / 039323 International Publication No. WO2017 / 002981 JP 2017-73334 A JP 2012-3938 A

  Generally, when such a system is installed in a vehicle, the battery is likely to be exposed to a high temperature environment, and the battery is required to have excellent heat resistance. There is also a need for a battery that is less likely to deteriorate in characteristics even after being placed in a high temperature environment for a long time, and can exhibit good load characteristics in a low temperature environment.

  In addition, in-vehicle batteries can maintain sufficient output characteristics even when stored for a long time in a high-temperature environment, and can be discharged well even after being stored in a low-temperature environment after such storage. There is a strong demand for ensuring the characteristics, and further improvement of the battery configuration is desired.

    As described above, in a vehicle emergency notification system, while a non-aqueous electrolyte primary battery is used as a power source, an application request for a secondary battery that can be charged and discharged several tens of times for reasons such as ease of maintenance There is.

Furthermore, in emergency call systems, there is also a request to ensure high reliability so that even when a vehicle encounters an accident and receives a strong impact, the battery configuration is further improved. Is desired.

  The present invention has been made in view of the above circumstances, and an object thereof is to be a non-rechargeable battery capable of repeated charge and discharge and having excellent storage characteristics under a high temperature environment and low temperature discharge characteristics and excellent in reliability. The object is to provide a water electrolyte battery.

The non-aqueous electrolyte battery of the present invention that has achieved the above object includes at least one negative electrode active material selected from the group consisting of lithium, a lithium alloy, an element that can be alloyed with lithium, and a compound containing the element. A non-aqueous electrolyte battery comprising a negative electrode, an electrode body in which a positive electrode is stacked via a separator, and a non-aqueous electrolyte, wherein the separator includes a porous membrane (I) mainly composed of a thermoplastic resin. And a porous layer (II) mainly comprising a needle-like filler having a heat-resistant temperature of 150 ° C. or higher.

  According to the present invention, it is possible to provide a non-aqueous electrolyte battery capable of repeated charge and discharge, having excellent storage characteristics under a high temperature environment, and having excellent reliability.

It is sectional drawing which represents typically an example of the negative electrode (negative electrode precursor) used for the non-aqueous electrolyte battery of this invention. It is a fragmentary longitudinal cross-sectional view which represents typically an example of the non-aqueous electrolyte battery of this invention. FIG. 3 is a perspective view of FIG. 2.

Hereinafter, the nonaqueous electrolyte battery of the present invention will be described in detail.

<Negative electrode>
The negative electrode of the nonaqueous electrolyte battery contains at least one negative electrode active material selected from the group consisting of Li (metal Li), Li alloy, an element that can be alloyed with Li, and a compound containing the element. used.

(Anode using Li as an anode active material)
When the negative electrode active material is Li, for example, the Li foil may be used as it is, or may be a negative electrode having a structure in which the Li foil is attached to one side or both sides of the current collector.

  In the case of using a current collector, the current collector may be made of copper (Cu), nickel (Ni), titanium (Ti), iron (Fe), stainless steel, etc. Examples thereof include plain weave wire mesh, expanded metal, lath mesh, punching metal, metal foam, foil (plate) and the like. The thickness of the current collector is, for example, preferably 10 to 50 μm, and more preferably 40 μm or less.

(Anode using Li alloy as anode active material)
Examples of Li alloys that can be used as negative electrode active materials include Li-Al alloys.

  In the case where the negative electrode active material is a Li-Al alloy, for example, an Al foil (including an Al alloy foil, hereinafter the same) in which a Li-Al alloy is formed on the surface can be used as a negative electrode. In addition, a laminate in which a Li layer (a layer containing Li) for forming a Li-Al alloy is bonded to the surface of an Al layer (a layer containing Al) composed of an Al foil or the like is used. By bringing this laminate into contact with the non-aqueous electrolyte in the battery, it is possible to form a Li-Al alloy on the surface of the Al layer to form a negative electrode (having a Li-Al alloy in the non-aqueous electrolyte battery) First method for forming a negative electrode). In the case of such a negative electrode, a laminate having a Li layer on only one side of the Al layer may be used, or a laminate having a Li layer on both sides of the Al layer may be used. The laminate can be formed, for example, by pressure bonding an Al foil and a metal Li foil (including a Li alloy foil; the same shall apply hereinafter).

  Furthermore, for the negative electrode, a negative electrode precursor having an Al layer composed of Al foil or the like is used, and by charging a battery assembled using this negative electrode precursor, a Li-Al alloy is formed on the surface of the Al layer. It can also be formed into a negative electrode (a second method of forming a negative electrode having a Li-Al alloy in a non-aqueous electrolyte battery). That is, a Li—Al alloy was formed at least on the surface side by electrochemically reacting Al on at least the surface side of the Al layer according to the negative electrode precursor with Li ions in the non-aqueous electrolyte by charging the battery. It can also be a negative electrode. Such a negative electrode uses, for example, a metal oxide containing Li used as a positive electrode active material of a lithium ion secondary battery as a positive electrode, and deposits Li ions eluted from the positive electrode on the surface of the Al layer of the negative electrode during charging. Can be produced.

  A collector can also be used for the negative electrode which uses Li-Al alloy as a negative electrode active material. In the case of using an Al foil having a Li-Al alloy formed on the surface in advance for the negative electrode, a metal foil, a metal mesh or the like serving as a current collector on the surface of the Al foil on which the Li-Al alloy is not formed May be crimped.

  Moreover, when forming a Li-Al alloy in a battery and using it as a negative electrode, when using the laminated body which has Li layer, it has an Al layer on one side of a negative electrode collector, and the negative electrode collection of Al layer, for example A laminate having an Li layer on the surface opposite to the current collector may be used, and an Al layer is provided on both surfaces of the negative electrode current collector, and the surface of each Al layer opposite to the negative electrode current collector is used. You may use the laminated body which has Li layer. Furthermore, in the case of forming a Li—Al alloy by charging a battery assembled using a negative electrode precursor, for example, a laminate having an Al layer on one side of the negative electrode current collector is used as the negative electrode precursor. You may use and you may use the laminated body which has Al layer on both surfaces of a negative electrode collector as a negative electrode precursor. The negative electrode current collector and the Al layer (Al foil) may be laminated by pressure bonding or the like, and a clad material of the negative electrode current collector (metal foil) and Al layer (Al foil) made of copper, nickel, etc. It is also possible to use a joined body (such as a laminated metal foil) of an Al metal layer for forming a Li—Al alloy and a metal base material layer acting as a current collector.

  The thickness of the laminate for forming the negative electrode and the thickness of the Al layer according to the negative electrode precursor (However, in the case of using a current collector and providing the Al layer on both sides of the current collector, Is preferably 10 μm or more, more preferably 20 μm or more, still more preferably 30 μm or more, and preferably 150 μm or less, more preferably 70 μm or less, More preferably, it is 50 μm or less.

  The thickness of the Li layer related to the laminate for forming the negative electrode (however, when a current collector is used, an Al layer is provided on both surfaces of the current collector, and the Li layer is provided on the surface of each Al layer) When providing, or when providing a Li layer on both sides of an Al layer without using a current collector, the thickness per side is preferably 20 μm or more, more preferably 30 μm or more, and And 80 μm or less, and more preferably 70 μm or less.

  As the current collector in the negative electrode using the Li alloy as the negative electrode active material, the same ones as those exemplified above as the current collector usable for the negative electrode using Li as the negative electrode active material can be used.

  In addition, 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) which is not alloyed with Li acting as a current collector are used in advance A method of laminating a Li layer (Li foil or the like) on the surface of the Al metal layer and reacting Li of the Li layer with Al of the Al metal layer, or the Al metal layer and the metal substrate layer The assembly of the invention is used as it is for assembly of a battery, and at least the surface side of the Al metal layer is electrochemically reacted with Li ions in the non-aqueous electrolyte by charging after assembly. Is a Li-Al alloy, and an Al active layer including the Li-Al alloy is joined to the surface of the metal base layer, for example, a metal foil serving as a current collector and an Al foil are simply used. Stacked negative electrode It can be compared with using, more suppressed increase in internal resistance during storage of the nonaqueous electrolyte battery.

  When a negative electrode is formed by the first method using a joined body of the Al metal layer and the metal base layer, a metal base layer that is not alloyed with Li (hereinafter simply referred to as “base layer”) A laminate in which a Li layer is formed by, for example, bonding a Li foil to the surface of an Al layer of a laminated metal foil formed by joining an aluminum metal layer (hereinafter simply referred to as "Al layer") use.

  The base material layer is a metal such as copper (Cu), nickel (Ni), titanium (Ti), iron (Fe), or an alloy of these elements and other elements (however, it reacts with Li such as stainless steel) Alloy). Specifically, it is formed of a foil of the above metal or alloy, a vapor deposition film, a plating film or the like.

  The Al layer can be composed of pure Al or an Al alloy having an additive element for the purpose of improving strength, specifically, a foil, vapor deposition film, plating film, or the like thereof. .

  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 non-aqueous 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, the Li foil Li and the Al layer Al react with each other in the presence of the non-aqueous electrolyte, and the Al layer Li foil is bonded to the side. A Li-Al alloy is formed on the surface of the (separator side) and changes to an Al active layer. That is, the Li—Al alloy formed in the nonaqueous electrolyte battery is present at least on the surface side (Li foil side) of the Al active layer of the negative electrode.

  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. May be joined. Then, in the laminate formed by bonding the laminated metal foil formed by bonding the base material layer and the Al layer with the Li foil, when the Al layer is bonded to one side of the base material layer The Li layer may be bonded to the surface of the Al layer (the surface not bonded to the base layer), and as shown in FIG. 1, when the Al layer is bonded to both sides of the base layer, The Li foil may be attached to the surface of the both Al layers (the surface not bonded to the base layer).

  In addition, when an Al layer is bonded to both surfaces of a base material layer and a Li-Al alloy is formed on the surface side of both Al layers, the Al layer is bonded to one surface of the base material layer, and the Al layer As compared with the case of forming a Li-Al alloy on the surface side of the layer, it is possible to further suppress the deformation (such as bending) of the negative electrode and the characteristic deterioration of the battery associated therewith.

  Hereinafter, the case where the base material layer is Ni (Ni foil) will be described as an example, but the same applies to the case where the base material layer is a material other than Ni.

  Examples of the laminated metal foil formed by joining a Ni layer and an Al layer include a clad material of Ni foil and Al foil, and a laminated film in which Al is vapor-deposited on Ni foil to form an Al layer.

  As a Ni layer according to a laminated metal foil formed by joining a Ni layer and an Al layer, a layer composed of Ni (and unavoidable impurities), zirconium (Zr), chromium (Cr), zinc (Zn) as an alloy component , Copper (Cu), iron (Fe), silicon (Si), phosphorus (P) and the like in a total amount of 20% by mass or less, the balance being Ni and a layer made of an Ni alloy with inevitable impurities. .

  Moreover, as an Al layer which concerns on the laminated metal foil which joined and formed Ni layer and Al layer, the layer which consists of Al (and an unavoidable impurity), iron (Fe), nickel (Ni), cobalt (as an alloy component) Co), manganese (Mn), chromium (Cr), vanadium (V), titanium (Ti), zirconium (Zr), niobium (Nb), molybdenum (Mo) and the like in a total amount of 50% by mass or less, A layer etc. which remainder consists of Al and Al alloy which is an unavoidable impurity are mentioned.

  In the laminated metal foil formed by joining the Ni layer and the Al layer, the Al layer is assumed to have a thickness of 100 in order to make the ratio of the Li-Al alloy to be the negative electrode active material equal to or more than a certain level. Is preferably 20 or more, more preferably 50 or more, and 70 or more. However, when the Al layer is bonded to both surfaces of the Ni layer, the thickness per side. It is particularly preferred. Also, in the laminated metal foil formed by joining the Ni layer and the Al layer to enhance the current collection effect and sufficiently hold the Li-Al alloy, when the thickness of the Ni layer is 100, the Al layer The thickness is preferably 180 or less, more preferably 150 or less, particularly preferably 120 or less, and most preferably 100 or less.

  The thickness of the Ni layer is preferably 10 to 50 μm, and more preferably 40 μm or less. In addition, the thickness of the Al layer (however, in the case of bonding the Al layer to both sides of the Ni layer, the thickness per side) is preferably 5 μm or more, more preferably 10 μm or more, and 15 μm or more In particular, it is 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 bonding the Ni layer and the Al layer is preferably 50 μm or more, more preferably 60 μm or more, in order to set the capacity of the negative electrode to a certain level or more. In order to set the capacity ratio with the positive electrode active material in an appropriate range, it is preferably 200 μm or less, more preferably 150 μm or less, and particularly preferably 120 μm or less.

  When the base material layer is a Cu layer instead of the Ni layer, the Cu layer may be a layer made of Cu (and inevitable impurities), an alloy component such as Zr, Cr, Zn, Ni, Si, P, etc. In a total amount of 1% by mass or less, with the remainder being a layer composed of Cu and a Cu alloy as an unavoidable impurity. The preferred thickness of the Cu layer (the preferred thickness of the Al layer when the thickness of the Cu layer is 100) and the preferred thickness of the laminated metal foil when the Cu layer is used are the same as when the Ni layer is used.

  As a Li foil used for a negative electrode precursor (including a negative electrode precursor composed of a laminated metal foil in which a base material layer and an Al layer are joined, and a negative electrode precursor composed of other than the laminated metal foil) And Ll (and unavoidable impurities), and alloy components including Fe, Ni, Co, Mn, Cr, V, Ti, Zr, Nb, Mo, etc. in a total amount of 40% by mass or less, with the balance being Li In addition, a foil made of a Li alloy, which is an inevitable impurity, may be used.

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

  That is, by causing Al on at least the surface side of the Al metal layer of the laminated metal foil to react electrochemically with Li ions in the non-aqueous electrolyte by charging the battery, a Li-Al alloy is formed at least on the surface side. An Al active layer can also be used.

  According to the second method using the laminated metal foil to which the Li foil is not bonded as a negative electrode precursor, the manufacturing process of the battery 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. Preferably, the negative electrode is formed by the first method (the Al active layer of the negative electrode is formed), and the battery is assembled using the negative electrode precursor according to the first method, and the battery is further charged to form the negative electrode (Al active layer of negative electrode may be formed).

  In a non-aqueous electrolyte battery using a bonded body of the base material layer and the Al layer (such as the above-mentioned laminated metal foil) as a negative electrode precursor, the crystal structure of the substance acting as a negative electrode active material is well maintained to make the potential of the negative electrode In the case of forming the Al active layer of the negative electrode by any of the first method and the second method, from the viewpoint of stabilizing and securing more excellent storage characteristics, in the Al active layer of the negative electrode It is preferable to use the battery in a range in which the content of Li is 48 atomic% or less when the total of Li and Al is 100 atomic%. That is, at the time of charging the battery, it is preferable to stop the charging in a range where the Li content of the Al active layer does not exceed 48 atomic%. Moreover, from the viewpoint of reaction spot suppression at the time of Li-Al alloy formation, it is more preferable to stop the charging in a range where the Li content is 29 atomic% or less, and the charging is performed in a range of 20 atomic% or less. It is particularly preferred to stop.

  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 set it as the laminated structure of the Li-Al alloy layer and the Al layer which remain | survives on the base-material 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 of α phase and β phase or β phase), On the other hand, it is presumed that the Al layer in the vicinity of the junction with the base material layer remains as the original Al layer without being substantially reacted with Li, or the Li content becomes lower than on 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.

  Note that the above “not substantially reacted with Li” means that Al is maintained in the state of the α phase, including the state in which Li is dissolved in a range of several atoms at% or less. Do.

  Further, in the non-aqueous electrolyte battery, it is preferable to charge the battery to a range in which the content of Li is 7 atomic% or more when the total of Li and Al is 100 atomic%. If it is this range, the problem of reaction spots at the time of Li-Al alloy formation hardly occurs.

  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 determined, and the content of Li is calculated from the value.

  In order to facilitate realization of the use condition of the battery as described above, in the case of forming a negative electrode by the first method in a non-aqueous electrolyte battery, the thickness of the Al layer at the time of battery assembly is selected in the negative electrode precursor used. The thickness of the Li layer bonded to the Al layer is preferably 20 or more, more preferably 30 or more, and preferably 80 or less, preferably 70 or less. More desirable.

  The specific thickness of the Li foil is preferably 20 μm or more, more preferably 30 μm or more, and preferably 80 μm or less, more preferably 70 μm or less, per one side of the laminate. .

(Anode using an element that can be alloyed with Li or a compound containing the element as a cathode active material)
Examples of elements that can be alloyed with Li that can be used as the negative electrode active material include silicon (Si) and tin (Sn). Examples of the compound containing an element that can be alloyed with Li that can be used as the negative electrode active material include oxides such as Si and Sn.

  When an element capable of alloying with Li or a compound containing the element is used as a negative electrode active material, a negative electrode having a structure in which a negative electrode mixture layer containing the negative electrode active material is formed on one side or both sides of a current collector can be used. .

  The negative electrode having the negative electrode mixture layer is a paste obtained by dispersing a negative electrode active material and a binder, and further, a conductive auxiliary used as needed, in a solvent such as N-methyl-2-pyrrolidone (NMP) or water Or a slurry-like negative electrode mixture-containing composition (however, the binder may be dissolved in a solvent), which is applied to one side or both sides of the current collector and dried, and then calendered as necessary. It can manufacture through the process of performing press processing, such as a process.

  Examples of the binder for forming the negative electrode mixture layer include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), styrene butadiene rubber (SBR), and carboxymethyl cellulose (CMC). In addition, when the conductive additive is included in the negative electrode mixture layer, as the conductive aid, natural graphite (such as flaky graphite), graphite such as artificial graphite (graphitic carbon material); acetylene black, ketjen black, Examples thereof include carbon blacks such as carbon blacks such as carbon blacks such as channel blacks, furnace blacks, lamp blacks, and thermal blacks.

  In the negative electrode using an element capable of alloying with Li or a compound containing the element as a negative electrode active material, the negative electrode active material may be doped in advance with Li ions, and this may be used for manufacturing the negative electrode. Alternatively, the negative electrode active material in a negative electrode manufactured using the negative electrode active material may be doped with Li ions, and the negative electrode in this state may be used for manufacturing a battery.

  As a composition of a negative mix layer, it is preferable that a negative electrode active material shall be 80-99.8 mass%, for example, and a binder shall be 0.1-10 mass%. Furthermore, when the negative electrode mixture layer contains a conductive auxiliary, the amount of the conductive auxiliary in the negative electrode mixture layer is preferably 0.1 to 10% by mass. Moreover, it is preferable that the thickness (thickness per single side | surface of a collector) of a negative mix layer is 10-100 micrometers.

  The current collector in the negative electrode using the element capable of alloying with Li or a compound containing the element as the negative electrode active material is the same as the current collector that can be used in the negative electrode using Li as the negative electrode active material. Things can be used.

  A lead body for electrically connecting to other members in the battery can be attached to the negative electrode according to a conventional method. In addition, when using the said laminated body as a negative electrode precursor used by the 1st method of forming a negative electrode, and a 2nd method, a negative electrode lead body can be provided in the Ni layer.

<Positive electrode>
For the positive electrode according to the non-aqueous electrolyte battery of the present invention, for example, one having a positive electrode mixture layer containing a positive electrode active material, a conductive additive, a binder and the like on one side or both sides of the 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.) Layer structure lithium-containing composite oxide, LiMn ₂ O ₄ or a lithium manganese oxide of spinel structure in which a part of the elements is substituted by another element, LiM ² PO ₄ (M ² : Co, Ni, Mn, Fe, etc. And olivine type compounds represented by As the lithium-containing composite oxide having a layered structure, lithium cobalt oxide such as LiCoO ₂ or LiNi _1-a Co _a-b Al _b O ₂ (0.1 ≦ a ≦ 0.3, 0.01 ≦ b ≦ 0 And 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. etc. can be illustrated.

  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 compounds exemplified above may be used, or two or more may be used in combination. However, since it is high in capacity and excellent in storage stability, lithium-containing composites It is preferable to use an oxide, particularly preferably the following general composition formula (1),
^{_{Li 1 + x Ni 1-y}} -z M 1 y M 2 z O 2 (1)
[In the general composition formula (1), M ¹ contains at least one element of Co, Mn, Al, Mg, Zr, Mo, Ti, Ba, W and Er, and M ² is Li, Ni and an element other than M ^1, is -0.1 ≦ x ≦ 0.1,0 ≦ y ≦ 0.5,0 ≦ z ≦ 0.05. ] It is a lithium containing complex oxide containing Ni represented.

  Examples of conductive assistants relating to the positive electrode mixture layer include carbon blacks such as acetylene black; ketjen black; channel black, furnace black, lamp black, thermal black and the like; carbon 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 composition can be prepared, applied to one side or both sides of the current collector, and dried, and then subjected to a pressing process as required.

  Alternatively, a formed body may be formed using the positive electrode mixture, and part or all of one side of the formed body may be bonded to a 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. Is preferred. The thickness of the positive electrode mixture layer is preferably 30 to 300 μm per side of the current collector.

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

  The capacity ratio of the positive electrode to be combined with the negative electrode may be set so that the content of Li is 7 to 48 atomic% when the total of Li and Al in the negative electrode at the end of charging is 100 atomic%, and further 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.

<Separator>
The separator used is a laminated separator having a porous film (I) mainly composed of a thermoplastic resin and a porous layer (II) mainly composed of a needle-like filler having a heat resistant temperature of 150 ° C. or higher.

  In the present specification, “heat-resistant temperature is 150 ° C. or more” means that no deformation such as softening occurs at least at 150 ° C.

  Further, the laminated separator may have a shutdown characteristic.

  In the case where the laminated separator has a shutdown characteristic, for example, the porous film (I) may mainly ensure the shutdown function. When the battery reaches or exceeds the melting point of the thermoplastic resin, which is the main component of the porous membrane (I), the thermoplastic resin related to the porous membrane (I) melts and plugs the pores of the separator, and electrochemical A shutdown that suppresses the progress of the reaction occurs.

  When the laminated separator also has shutdown characteristics, the thermoplastic resin that is the main component of the porous membrane (I) is preferably a resin having a melting point of 140 ° C. or lower, and specifically includes polyethylene. Further, as the form of the porous membrane (I), a dispersion containing particles of polyethylene is applied to a microporous membrane usually used as a separator for batteries, a base material such as a non-woven fabric, and the like, and then dried. Examples thereof include sheet-like materials such as those obtained. Here, among the total volume of the constituent components of the porous membrane (I) [the total volume excluding the pores. The same applies to the volume content of the constituent components of the porous membrane (I) and the porous layer (II) according to the separator. In the above, the volume content of the resin having a melting point of 140 ° C. or less as the main component is 50% by volume or more, and more preferably 70% by volume or more. In addition, when forming porous membrane (I) with the microporous film of the said polyethylene, for example, the volume content rate of resin whose melting | fusing point is 140 degrees C or less will be 100 volume%.

  Examples of the thermoplastic resin that is the main component of the porous membrane (I) for the separator include polypropylene, polyester (aromatic polyester represented by wholly aromatic polyester, polybutylene terephthalate, in addition to the resin having a melting point of 140 ° C. or lower. Etc.), polyacetal, polyamide [aromatic polyamide represented by wholly aromatic polyamide (aramid), nylon, etc.], polyether (such as aromatic polyether represented by wholly aromatic polyether), polyketone (fully aromatic) Aromatic polyketones represented by polyketones), polyimides, polyamideimides, polyphenylene sulfides, polybenzimidazoles, polyetheretherketones, polyethersulfones, poly (para-phenylenebenzobisthiazoles), poly (para-phenylene-2, 6 -Benzobisoxazole), polyurethane, cellulose, polyvinyl alcohol and the like. As the shape of the porous membrane (I), a microporous membrane composed of these thermoplastic resins is suitable.

The filler, which is the main component of the porous layer (II) related to the separator, has a heat-resistant temperature of 150 ° C. or higher and is needle-shaped (needle-shaped filler).

Usually, when the viscosity of the electrolyte increases in a low temperature environment, Li ions are difficult to move. When a plate-like filler having a flat surface is used, the flat surface of the filler is easily oriented in the planar direction (direction orthogonal to the thickness direction) of the porous layer (II), and the path of the pores of the porous layer (II) The length tends to be long, but if the filler is needle-shaped, the path length of the pores of the porous layer (II) is shortened, so that the movement of Li ions from the negative electrode to the positive electrode is facilitated. It has been found that the discharge characteristics are improved.

  The needle-like filler does not have a flat surface, and the aspect ratio is preferably larger than 3 and more preferably 10 or more. With such an aspect ratio needle filler, thermal shrinkage in the direction corresponding to the MD direction of the microporous film constituting the porous layer (I) in the separator, and lithium ion in the porous layer (II) It is possible to better suppress the decrease in the transmission speed. In addition, the aspect ratio of the acicular filler is preferably 300 or less, and more preferably 100 or less.

In addition, the details are unknown, but by using the needle filler, the mechanical strength of the porous layer (II) is increased by the filler being randomly oriented than when using the plate filler, It is considered that the impact resistance of the battery can be improved.

  In addition, the aspect ratio of the acicular filler referred to in the present specification is the length of the longest portion in the filler (long axis length) and the length of the longest portion in the direction orthogonal to the longest portion in the filler (short axis). (Long axis length / short axis length), specifically, the acicular filler is dispersed in a medium (pure water or the like that does not dissolve the acicular filler). After the dispersion was dried and the medium was removed, a 10000x transmission electron micrograph was taken, the major axis length and minor axis length of 30 fillers were measured, and the average value of the major axis lengths. The average value of the short axis length is obtained, and the value is obtained by the ratio of these average values.

  Examples of acicular fillers that can be used for the porous layer (II) include acicular boehmite, acicular alumina, acicular titanium oxide, acicular iron oxide, acicular silica, acicular magnesium oxide, acicular zinc oxide, Needle-like magnesium hydroxide, needle-like sepiolite wollastonite, needle-like potassium titanate, needle-like Zonotolite, needle-like dawsonite, basic magnesium sulfate fiber, other whiskers, etc. are mentioned, and one of these is used. May be used alone, or two or more of them may be used in combination. Among these, those having less chemical and physical change and low dissolved ion concentration at high temperature or in the presence of an electrolytic solution of a battery are preferable, and alumina, boehmite and silica are particularly preferable.

  In addition, the porous layer (II) can contain a filler having a heat resistant temperature of 150 ° C. or higher and a shape other than the needle shape (spherical shape, ellipsoid shape, plate shape, etc.) together with the needle shape filler. Examples of the filler having a shape other than the needle shape include the following inorganic particles and organic particles.

Specific examples of the constituent material of the inorganic particles include, for example, iron oxide, Al ₂ O ₃ (alumina), SiO ₂ (silica), TiO ₂ , BaTiO ₃ , ZrO ₂ and other inorganic oxides; aluminum nitride, silicon nitride, etc. Inorganic nitrides of the above; poorly soluble ionic crystals such as calcium fluoride, barium fluoride and barium sulfate; covalent bonds such as silicon and diamond; clays such as montmorillonite; Here, the inorganic oxide may be a mineral resource-derived substance such as boehmite, zeolite, apatite, kaolin, mullite, spinel, olivine, mica or the like or a artificial product thereof. The metal, SnO _2, tin - conductive oxide such as indium oxide (ITO), carbon black, the surface of the conductive material is exemplified by such a carbonaceous material such as graphite, a material having an electrical insulating property ( For example, the particle | grains which gave the electrical insulation property by coat | covering with the said inorganic oxide etc. may be sufficient.

  Moreover, as organic particles (organic powder), cross-linked poly (methyl methacrylate), cross-linked polystyrene, cross-linked poly (divinyl benzene), cross-linked styrene-divinyl benzene copolymer, polyimide, melamine resin, phenol resin, benzoguanamine-formaldehyde condensate, etc. Various cross-linked polymer particles, heat-resistant polymer particles such as polysulfone, polyacrylonitrile, aramid, polyacetal, thermoplastic polyimide and the like can be exemplified. Further, the organic resin (polymer) constituting the organic particles of the polymer is a mixture, modified body, derivative, copolymer (random copolymer, alternating copolymer, block copolymer, graft copolymer) of the above-exemplified materials. Polymer) or a crosslinked product (in the case of the above-mentioned heat-resistant polymer).

  The average particle diameter D50% of the needle-like filler and the non-needle-like filler is, for example, preferably 0.01 μm or more, more preferably 0.3 μm or more, and 10 μm or less Preferably, it is 3 μm or less. In addition, the average particle diameter of the particles such as the acicular filler referred to in this specification is determined by using a laser scattering type particle size distribution meter (for example, Microtrack particle size distribution measuring device “HRA9320” manufactured by Nikkiso Co., Ltd.) It means D50%, which is the value of the particle diameter at a volume-based cumulative fraction of 50% measured by dispersing in a medium that does not dissolve (such as pure water that does not dissolve the filler).

  The amount of the acicular filler having a heat resistant temperature of 150 ° C. or higher in the porous layer (II) is 50% by volume or more and 70% by volume or more in the total volume of the constituent components of the porous layer (II). Preferably, it is 80 volume% or more, more preferably 90 volume% or more. By making the acicular filler in the porous layer (II) high as described above, the heat shrinkage resistance of the entire separator can be improved better, and the lithium secondary battery becomes hot. Generation | occurrence | production of the short circuit by the direct contact of a positive electrode and a negative electrode can be suppressed more favorably.

  In addition, it is preferable that the porous layer (II) contains an organic binder in order to bind the above-mentioned fillers or to bind the porous layer (II) and the porous film (I), From such a viewpoint, the preferable upper limit of the amount of the filler (B) in the porous layer (II) is, for example, 99% by volume in the total volume of the components of the porous layer (II). When the amount of the filler (B) in the porous layer (II) is less than 70% by volume, for example, the amount of the organic binder in the porous layer (II) needs to be increased, but in that case the porous The pores of the layer (II) may be filled with the organic binder and, for example, the function as a separator may be lost.

  As an organic binder used for the porous layer (II), the fillers and the porous layer (II) and the porous membrane (I) can be bonded well, are electrochemically stable, and are used for an electrochemical element. There is no particular limitation as long as it is stable with respect to the non-aqueous electrolyte. Specifically, fluororesin (such as PVDF), fluororubber, SBR, CMC, hydroxyethyl cellulose (HEC), polyvinyl alcohol (PVA), polyvinyl butyral (PVB), polyvinyl pyrrolidone (PVP), poly N-vinylacetamide, Cross-linked acrylic resin, polyurethane, epoxy resin and the like can be mentioned. These organic binders may be used alone or in combination of two or more.

  The laminate type separator is, for example, a composition for forming a porous layer (II), which contains the filler, the organic binder and the like and a solvent (the organic solvent such as water and ketones) in the porous membrane (I) After applying a slurry, a paste, etc., it can be manufactured by drying at a predetermined temperature to form a porous layer (II).

  The multilayer separator may have one or more porous membranes (I) and one or more porous layers (II). Specifically, the porous layer (II) is disposed only on one side of the porous membrane (I) to form the laminated separator, for example, porous layers (II) on both sides of the porous membrane (I) May be used as the laminated separator. However, if the number of layers of the multilayer separator is too large, it is not preferable because the thickness of the separator is increased, which may increase the internal resistance of the battery or decrease the energy density. Is preferably 5 layers or less.

  The thickness of the separator (the laminated separator and other separators) is preferably 6 μm or more and more preferably 10 μm or more from the viewpoint of more reliably separating the positive electrode and the negative electrode. On the other hand, if the separator is too thick, the energy density of the battery may be reduced, so the thickness is preferably 50 μm or less, more preferably 30 μm or less.

  Further, the thickness of the porous membrane (I) [total thickness of the porous membrane (I) when there are a plurality of porous membranes (I)] is preferably 5 to 30 μm. Furthermore, the thickness of the porous layer (II) [total thickness of the plurality of porous layers (II)] is preferably 1 μm or more, more preferably 2 μm or more, and 4 μm or more Is more preferably 20 μm or less, more preferably 10 μm or less, and still more preferably 6 μm or less.

  The porosity of the separator is preferably 30 to 70%. Furthermore, the average pore diameter of the separator is preferably 0.01 μm or more, more preferably 0.05 μm or more, and preferably 1 μm or less, more preferably 0.5 μm or less.

  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 A non-protonic organic solvent such as a conductor, diethyl ether, or 1,3-propanesultone can be used alone or as a mixed solvent of two or more.

The lithium salt according to the non-aqueous electrolyte, 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, LiN At least one selected from (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], etc. Can be mentioned. The concentration of these lithium salts in the electrolyte is preferably 0.6 to 1.8 mol / l, and more preferably 0.9 to 1.6 mol / l.

  In addition, it is preferable that the non-aqueous electrolyte contains a nitrile compound as an additive. By using a non-aqueous electrolyte to which a nitrile compound is added, the nitrile compound is adsorbed on the surface of the positive electrode active material to form a film, and this film suppresses gas generation due to oxidative decomposition of the non-aqueous electrolyte. The swelling of the battery when stored in a high temperature environment can be suppressed.

  Examples of nitrile compounds to be added to the non-aqueous electrolyte include acetonitrile, propionitrile, butyronitrile, valeronitrile, benzonitrile, mononitriles such as acrylonitrile, malononitrile, succinonitrile, glutaronitrile, adiponitrile, 1,4-dicyanoheptane, and the like. 1,5-dicyanopentane (pimelonitrile), 1,6-dicyanohexane (suberonitrile), 1,7-dicyanoheptane (azelaonitrile), 2,6-dicyanoheptane, 1,8-dicyanooctane, 2,7-dicyanooctane 1,9-dicyanononane, 2,8-dicyanononane, 1,10-dicyanodecane, 1,6-dicyanodecane, dinitriles such as 2,4-dimethylglutaronitrile; cyclic nitriles such as benzonitrile; methoxyacetoni Lil alkoxy-substituted nitriles such as; include such is, it may be used only one of these, or two or more may be used. Among these nitrile compounds, dinitrile is more preferable, and adiponitrile, pimeronitrile and suberonitrile are further preferable.

  The content of the nitrile compound in the non-aqueous electrolyte used in the battery is preferably 0.1% by mass or more, and preferably 1% by mass or more, from the viewpoint of ensuring the above-described effects due to their use. Is more preferred. However, when the amount of the nitrile compound in the non-aqueous electrolyte is too large, the discharge characteristics at low temperature of the battery tend to be deteriorated. Therefore, the content of the nitrile compound in the non-aqueous electrolyte used in the battery is 10, from the viewpoint of making the discharge characteristics at a low temperature of the battery better by limiting the amount of the nitrile compound in the non-aqueous electrolyte to some extent. It is preferably at most mass%, more preferably at most 5 mass%.

  In addition, additives such as vinylene carbonates, 1,3-propane sultone, diphenyl disulfide, cyclohexyl benzene, biphenyl, fluorobenzene, and t-butyl benzene are added to these non-aqueous electrolytes for the purpose of further improving various characteristics of the battery. Can also be added as appropriate.

Furthermore, in the non-aqueous electrolyte battery of the invention, when the non-aqueous electrolyte to which the above-mentioned phosphoric acid compound is added is used, it is possible to maintain high load characteristics under low temperature environment after storage at high temperature. It is desirable to add compounds.

It is known that the phosphoric acid compound forms a SEI (Solid Electrolyte Interface) film on the surface of the positive electrode. On the other hand, since the non-aqueous electrolyte battery of the present invention has good load characteristics under a low temperature environment after high temperature storage, it was guessed that the above-mentioned phosphoric acid compound forms a thin and good film also on the negative electrode.

  In addition, since the surface coating is thinned, the amount of Li required for forming the coating is reduced. Therefore, in the secondary battery (nonaqueous electrolyte secondary battery) having the negative electrode active material, the irreversibility of the negative electrode It is presumed that the capacity decreases to lead to the improvement of charge and discharge efficiency.

  Examples of the phosphoric acid compound include mono (trimethylsilyl) phosphate, di (trimethylsilyl) phosphate, tris (trimethylsilyl) phosphate, dimethyltrimethylsilyl phosphate, methylbis (trimethylsilyl) phosphate, diethyltrimethylsilyl phosphate, Examples include diphenyl (trimethylsilyl) phosphate, tris (triethylsilyl) phosphate, tris (vinyldimethylsilyl) phosphate, mono (trimethylsilyl) phosphate, di (trimethylsilyl) phosphate, tris (trimethylsilyl) phosphate Dimethyltrimethylsilyl phosphate and methylbis (trimethylsilyl) phosphate are preferable, and tris (trimethylsilyl) phosphate is particularly preferable.

  The content of the phosphoric acid compound in the non-aqueous electrolyte used in the battery is preferably 0.1% by mass or more, from the viewpoint of securing the above-mentioned effect by the use better, 0.3 mass % Or more, more preferably 0.5% by mass or more, and most preferably 0.7% by mass or more. In addition, when the content is too large, the thickness of the SEI film that can be formed on the electrode interface increases, which may increase the resistance and reduce the load characteristics. Therefore, in the non-aqueous electrolyte used in the battery The content of the phosphoric acid compound having a group represented by the general formula (1) in the molecule is preferably 8% by mass or less, more preferably 7% by mass or less, and 5% by mass or less Particularly preferred is 3% by mass or less.

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

<Electrode body>
In a non-aqueous electrolyte battery, a positive electrode and a negative electrode are stacked in layers with a separator interposed therebetween (without being wound, for example, the positive electrode and the negative electrode are interposed with the separator substantially parallel to the flat surface of the battery outer body). (Laminated electrode body) disposed in an overlapping state, or in the form of a wound body (wound electrode body) formed by spirally winding a strip-shaped positive electrode, a negative electrode, and a separator.

<Form of non-aqueous electrolyte battery>
In a non-aqueous electrolyte battery, for example, after loading a stacked or wound electrode assembly into an outer package, injecting a non-aqueous electrolyte into the outer package and impregnating the non-aqueous electrolyte into the electrode assembly, the opening of the outer package is formed. It is manufactured by sealing. 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. More specifically, as a battery having an outer can, a flat type having a battery case that caulks and seals the outer can and the sealing plate via a gasket, or welds and seals the outer can and the sealing plate. (Coin-shaped, button-shaped); A lid is placed at the opening of the bottomed cylindrical (cylindrical, square, etc.) outer can, and the gasket is used for caulking and sealing, or the outer can and lid And a tubular shape that is sealed by welding.

  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% is The storage characteristics of the non-aqueous electrolyte battery can be favorably exhibited by setting the charge end condition to be 7 to 48 atomic% at the end of charge.

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

Example 1
<Fabrication of negative electrode>
988 mm x 44.5 mm where aluminum foil of 20 μm thickness is laminated on both sides of 35 μm thick Cu foil (tensile strength: 220 N / mm ² , volume specific resistance: 2 × 10 ^-6 Ω · cm) A clad material (laminated metal foil) having a size was used as a negative electrode precursor. A Cu foil for current collection was ultrasonically welded to the end of the clad material, and then an ultrasonic weld of a Ni tab for conductive connection with the outside of the battery was ultrasonically welded to the end of the Cu foil. Used for.

<Fabrication of positive electrode>
On the other hand, the positive electrode was produced as follows. LiNi _0.78 Co _0.20 Al _0.02 O _{2 as} a positive electrode active material: 97 parts by mass, conductive auxiliary agent (carbon black): 1.5 parts by mass, and VDF-CTFE as a binder: 1.5 parts by mass Is mixed to form a positive electrode mixture, NMP as a solvent is added to the positive electrode mixture, and using "CLEAR MIX CLM 0.8 (trade name)" manufactured by M. Technic Co., Ltd., the rotation speed is 10000 min ^-1 . The treatment was performed for 30 minutes to obtain a paste-like mixture. NMP which is a solvent was further added to this mixture, and the mixture was treated at a rotation speed of 10,000 min ⁻¹ for 15 minutes to prepare a positive electrode mixture-containing slurry. This was applied to both sides of an Al foil having a thickness of 12 μm, dried, and pressed to form a positive electrode mixture layer having a mass of 15 mg / cm ² per side of the Al foil current collector. In addition, the positive mix layer was not formed in a part of application | coating surface of a slurry, but the location which Al foil exposed was provided. A strip-like positive electrode having a length of 974 mm and a width of 43 mm was produced by ultrasonic welding of an Al tab for conductive connection with the outside of the battery at the location where the Al foil was exposed.

<Preparation of Separator>
Add 5 kg of acicular alumina, 5 kg of ion-exchanged water, and 0.5 kg of a dispersing agent (aqueous polycarboxylic acid ammonium salt, solid concentration 40 mass%), and use an internal volume of 20 L and a ball mill of 40 revolutions per minute. A dispersion was prepared by time disintegration treatment. Using this dispersion, the average particle diameter and aspect ratio of acicular alumina were measured by the method described above. The average particle diameter was 0.6 μm and the aspect ratio was 30.

  To 500 g of the above dispersion, 0.5 g of xanthan gum as a thickener and 17 g of a resin binder dispersion (modified polybutyl acrylate, solid content 45% by mass) as a binder were added and stirred for 3 hours with a three-one motor to obtain uniform porosity. A slurry (solid content ratio 50% by mass) for formation of a solid layer (II) was prepared.

Corona discharge treatment (discharge amount 40 W · min / m) on one side of a microporous membrane (thickness 12 μm, porosity 40%, average pore diameter 0.08 μm, PE melting point 135 ° C.) made of PE which is a porous membrane (I) ² ) Apply the above slurry for forming the porous layer (II) to the treated surface with a microgravure coater, and dry to form a porous layer (II) with a thickness of 4 μm on one side of the porous membrane (I). Formed. The volume content of needle-like alumina in the separator was 90%, which was calculated based on the specific gravity of needle-like alumina of 3.9 g / cm ³ and the specific gravity of thickener and binder of 1.0 g / cm ³ .

<Fabrication of non-aqueous electrolyte battery>
The positive electrode and the negative electrode were laminated via the separator, wound in a spiral shape, and then crushed to form a flat electrode body. In the production of the electrode body, the surface side of the separator to which the acicular boehmite was bound was made to face the positive electrode.

Dissolve LiBF ₄ at a concentration of 1.2 mol / l in a mixed solvent of PC and MEC at a volume ratio of 1: 2, and then add 3% by mass of adiponitrile and 0.5% by mass of A non-aqueous electrolyte was prepared by adding γ-butyrolactone and tris (trimethylsilyl) phosphate in an amount of 1% by mass.

  The electrode body is inserted into a rectangular battery container made of aluminum alloy having a thickness of 0.8 mm, and after injecting the non-aqueous electrolyte, the battery container is sealed to obtain the structure shown in FIGS. A prismatic non-aqueous electrolyte battery of 103,450 size was assembled.

  The battery shown in FIGS. 2 and 3 will now be described. FIG. 2 is a partial sectional view of the battery. The positive electrode 11 and the negative electrode 12 are spirally wound through the separator 13 and then flattened. The non-aqueous electrolyte is accommodated in a rectangular (square cylindrical) battery container 14 as a flat wound electrode body 16 under pressure. However, in FIG. 2, in order to avoid complication, each layer of the positive electrode 11 and the negative electrode 12, a non-aqueous electrolyte, etc. are not shown in figure.

  The battery case 14 is made of an aluminum alloy and constitutes an outer package of the battery, and the battery case 14 doubles as a positive electrode terminal. And the insulator 15 which consists of PE sheets is arrange | positioned at the bottom part of the battery container 14, and it connects to each one end of the positive electrode 11 and the negative electrode 12 from the flat wound electrode body 16 which consists of the positive electrode 11, the negative electrode 12, and the separator 13. The positive electrode lead body 17 and the negative electrode lead body 18 are pulled out. A stainless steel terminal 21 is attached to a sealing lid plate 19 made of aluminum alloy for sealing the opening of the battery container 14 via a polypropylene insulating packing 20, and an insulator 22 is attached to the terminal 21. A stainless steel lead plate 23 is attached.

  And this cover plate 19 is inserted in the opening part of the battery container 14, and the opening part of the battery container 14 is sealed by welding the junction part of both, and the inside of a battery is sealed. Further, in the battery of FIG. 2, the cover plate 19 is provided with the non-aqueous electrolyte injection port 24, and a sealing member is inserted into the non-aqueous electrolyte injection port 24 by, for example, laser welding. It is sealed by welding to ensure the sealing property of the battery. Further, the cover plate 19 is provided with a cleavage vent 25 as a mechanism for discharging the internal gas to the outside when the temperature of the battery rises.

  In the battery of Example 1, the positive electrode lead body 17 is directly welded to the lid plate 19 so that the battery container 14 and the lid plate 19 function as a positive electrode terminal, and the negative electrode lead body 18 is welded to the lead plate 23. The terminal 21 functions as a negative electrode terminal by conducting the negative electrode lead body 18 and the terminal 21 through the lead plate 23. However, depending on the material of the battery container 14 or the like, the sign may be reversed. There is also.

  FIG. 3 is a perspective view schematically showing the appearance of the battery shown in FIG. 2. FIG. 3 is shown for the purpose of showing that the battery is a prismatic battery. FIG. 1 schematically shows a battery, and shows only specific ones of battery components. Further, also in FIG. 2, the portion on the inner circumferential side of the electrode body is not a cross section.

Example 2
Cladding material (lamination of 30 μm thick Al foil on both sides of 30 μm thick Ni foil (tensile strength: 490 N / mm ² , volume specific resistance: 6.8 × 10 ^-6 Ω · cm) A square nonaqueous electrolyte battery was produced in the same manner as in Example 1 except that (metal foil) was used as the negative electrode precursor.
ing.

Example 3
A clad material (laminated metal foil) in which an Al foil of 30 μm in thickness is laminated on both sides of a 30 μm thick Ti foil (tensile strength: 410 N / mm ² , volume specific resistance: 55 × 10 ⁻⁶ Ω · cm) A square non-aqueous electrolyte battery was produced in the same manner as in Example 1 except that the above was used as a negative electrode precursor.

Example 4
A clad material (laminated metal foil) in which an Al foil of 30 μm thickness is laminated on both sides of a 30 μm thick SUS304 foil (tensile strength: 600 N / mm ² , volume specific resistance: 72 × 10 ⁻⁶ Ω · cm) A square non-aqueous electrolyte battery was produced in the same manner as in Example 1 except that the above was used as a negative electrode precursor.

Example 5
A dispersion was obtained in the same manner as in Example 1 using needle-like boehmite instead of needle-like alumina. Using this dispersion, the average particle diameter and aspect ratio of acicular boehmite were measured by the method described above. The average particle diameter was 0.4 μm and the aspect ratio was 10. All except that the slurry for forming the porous layer (II) was prepared using this dispersion, and the porous layer (II) having a thickness of 4 μm was formed on one side of the porous membrane (I) using this slurry. A separator was obtained in the same manner as in Example 1. The volume content of acicular boehmite in the separator calculated with the specific gravity of acicular boehmite being 3.0 g / cm ³ was 92%. A square non-aqueous electrolyte battery was produced in the same manner as in Example 1 except that this separator was used.

Example 6
A dispersion was obtained in the same manner as in Example 1 except that needle-shaped silica was used instead of needle-shaped alumina. Using this dispersion, the average particle diameter and aspect ratio of acicular silica were measured by the method described above. The average particle diameter was 0.3 μm and the aspect ratio was 100. A slurry was prepared using this dispersion to form a porous layer (II), and using this slurry, a porous layer (II) having a thickness of 6 μm was formed on one side of the porous film (I). A separator was obtained in the same manner as in Example 1. The volume content of acicular silica in the separator calculated with the specific gravity of acicular silica being 2.2 g / cm ³ was 94%. A square non-aqueous electrolyte battery was produced in the same manner as in Example 1 except that this separator was used.

Example 7
A square nonaqueous electrolyte battery was produced in the same manner as in Example 1 except that tris (trimethylsilyl) phosphate was not added to the nonaqueous electrolyte.

Example 8
A square nonaqueous electrolyte battery was produced in the same manner as in Example 1 except that 5% of tris (trimethylsilyl) phosphate was added to the nonaqueous electrolyte.

Example 9
A negative electrode precursor was prepared by ultrasonically welding a Ni tab for conductive connection with the outside of the battery to an Al foil (No. 1N30 specified in JIS standard) with a thickness of 100 μm and a size of 988 mm × 44.5 mm. . Thereafter, a rectangular nonaqueous electrolyte battery was produced in the same manner as in Example 1.

Comparative Example 1
98 parts by mass of graphite having an average particle diameter D 50% of 22 μm, 1.0 parts by mass of CMC, and 1.0 parts by mass of SBR are mixed with ion exchanged water to prepare a water-based negative electrode mixture-containing paste did. The above negative electrode mixture-containing paste is applied to both sides of a 30 μm-thick Cu foil, dried, and calendered to give a negative electrode coating density of 1.58 g / cm ^{3 in} the mixture layer. The thickness of the mixture layer was adjusted to obtain a negative electrode. Further, a Ni tab was ultrasonically welded to the exposed portion of the copper foil, and a rectangular nonaqueous electrolyte battery was produced in the same manner as in Example 1.

Comparative example 2
A dispersion was obtained in the same manner as in Example 1 using plate-like alumina instead of needle-like alumina. It was 1 micrometer when the average particle diameter of plate-like alumina was measured by the method mentioned above using this dispersion liquid. The aspect ratio was determined from the ratio between the maximum length of the tabular surface of the plate-like particle and the thickness of the plate-like particle (maximum length of the tabular surface / thickness of the plate-like particle). That is, as described above, a transmission electron micrograph of 10000 times of the filler is taken, and the maximum length of the flat surface of the plate-like particle and the thickness of the plate-like particle are measured for 30 fillers. The average value of the and the average value of the minor axis lengths were determined, and the value was determined by the ratio of these average values. Here, the aspect ratio was 10. This filler dispersion liquid A separator was produced in the same manner as in Example 1 except that this dispersion liquid was used. The volume content of the plate-like alumina in the separator calculated by setting the specific gravity of the plate-like alumina to 3.9 g / cm ³ was 90%. A square non-aqueous electrolyte battery was produced in the same manner as in Example 1 except that this separator was used.

  About each battery of Examples 1-9 and Comparative Examples 1 and 2, after leaving it to stand for 24 hours from an assembly, it evaluated about the following items.

<High temperature storage characteristics>
About each battery of Examples 1-9 and Comparative Examples 1 and 2, the constant current (0.2C) -constant voltage (4.0V) charge was performed, and charge was stopped when the charge current fell to 0.01C. . Next, the battery was discharged at a constant current of 0.2 C (discharge termination voltage: 2 V) to measure a discharge capacity (initial discharge capacity), and charge was performed under the above-mentioned charge condition to make the battery fully charged. All the batteries had an initial discharge capacity of 1200 mAh.

  Each battery in a fully charged state was stored at 85 ° C. for 10 days, cooled to room temperature, and then discharged at a constant current of 240 mA (discharge end voltage: 2 V). Furthermore, charge under the above charge conditions and discharge at 240 mA (discharge termination 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 based on the recovery capacity of each battery when the recovery capacity of the battery of Comparative Example 2 was 100%. The results are shown in Table 1.

<Low temperature discharge characteristics>
In addition, for each battery after the recovery capacity measurement, charging under the above charging conditions and discharging at 1.5 C (discharging end voltage: 2 V) in an environment of −20 ° C. are performed in a low temperature environment after high temperature storage. The discharge capacity at was measured. The low temperature discharge characteristics of each battery were evaluated based on the discharge capacity of each battery when the discharge capacity of the battery of Comparative Example 2 was 100%. The results are shown in Table 1.

<Drop test>
In the batteries of Examples and Comparative Examples, a prismatic battery, that is, an exterior body composed of an exterior can and a lid is a hexahedron. In the drop test, the operation of dropping the battery from a height of 2.0 m is performed while sequentially changing the surface of the battery facing downward, and the dropping operation on all outer surfaces (six surfaces) of the battery is defined as one cycle. Repeatedly. Then, the reliability of the battery against falling was evaluated according to the following criteria, and the results are shown in Table 1.
A: No decrease in battery voltage is observed even after 16 cycles of the drop test.
○: A drop in battery voltage is observed during the drop test of 10 to 15 cycles.
X: Decrease in battery voltage is observed in 9 cycles or less of drop test.

  As shown in Table 1, in the batteries of Examples 1 to 9 of the present invention, the recovery capacity after storage for 10 days at 85 ° C. is 100% or more, and the discharge characteristics under a low temperature environment after recovery capacity measurement are 100. %, And even if the drop test is repeated 16 cycles, no drop in the battery voltage is observed, which indicates that the high temperature storage characteristics, the low temperature discharge characteristics and the reliability are excellent.

On the other hand, in Comparative Example 1 in which graphite is used for the negative electrode, the recovery capacity and the discharge capacity under a low temperature environment are significantly lower than 100%, indicating that the high temperature storage characteristics and the low temperature discharge characteristics are inferior. Further, in Comparative Example 2 using a separator using a plate-like alumina as a filler, the recovery capacity is 100%, but the low-temperature discharge characteristics are less than 100% and the low-temperature discharge characteristics are inferior. In addition, in the battery of Comparative Example 2 after the drop test, no abnormality such as rupture or ignition was observed in the battery, and only the battery voltage was lowered in some batteries. Confirmed that the reliability of the drop test was improved.

  The present invention can be practiced as other embodiments without departing from the scope of the present invention. The embodiments disclosed in the present application are one example, and the present invention is not limited to these embodiments. The scope of the present invention is interpreted with priority given to the description of the appended claims rather than the description in the foregoing specification, and all changes within the scope equivalent to the claims fall within the scope of the claims. included.

  The nonaqueous electrolyte battery of the present invention can be repeatedly charged and discharged, has good storage characteristics in a high-temperature environment, and is excellent in reliability. As described above, the present invention can be preferably applied to applications that are required to maintain a good capacity over a long period of time in a high temperature environment.

11 positive electrode 12 negative electrode 13 separator 14 battery container 15 insulator 16 winding electrode body 17 positive electrode lead body 18 negative electrode lead body 19 sealing lid plate 20 packing 21 terminal 22 insulator 23 lead plate 24 non-aqueous electrolyte inlet 25 cleavage vent

Claims (6)

An electrode body in which a negative electrode containing at least one negative electrode active material selected from the group consisting of lithium, a lithium alloy, an element capable of alloying with lithium, and a compound containing the above element and a positive electrode are stacked via a separator And a non-aqueous electrolyte battery comprising:
The separator is characterized by having a porous film (I) mainly composed of a thermoplastic resin, and a porous layer (II) mainly composed of a needle-like filler having a heat resistance temperature of 150 ° C. or higher. Non-aqueous electrolyte battery. The non-positive electrode according to claim 1, further comprising: a laminate including a metal base layer which is not alloyed with lithium, and an aluminum active layer joined to at least one surface of the metal base layer. Water electrolyte battery.   The nonaqueous electrolyte battery according to claim 1 or 2, wherein the metal base layer not alloyed with lithium is made of a metal selected from copper, nickel, titanium, and iron or an alloy thereof.   The non-aqueous electrolyte battery according to any one of claims 1 to 3, wherein the needle-like filler used for the separator contains at least one of alumina, boehmite and silica.   The aspect ratio of the said acicular filler is 30-100, The non-aqueous electrolyte battery in any one of Claims 1-4.   The nonaqueous electrolyte battery according to claim 1, wherein the nonaqueous electrolyte includes at least a phosphoric acid compound.

Images