JP5329018B2 - Battery separator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a separator preventing contraction at the time of abnormal heat generation. <P>SOLUTION: As for the separator for a battery, the separator is constructed of a fiber assembly such as a woven fabric, a non-woven fabric, and a mesh fabric, and the fiber assembly includes a fiber having a melting point of 150&deg;C or more such as, for example, aramide and polyimide. Thereby, by using the fiber having a melting point of 150&deg;C or more, the contraction of the separator can be prevented effectively even if the temperatures inside the battery reach around 200&deg;C and as a result, short circuit between the electrodes can be prevented effectively. <P>COPYRIGHT: (C)2006,JPO&amp;NCIPI

Description

  The present invention relates to a battery separator suitably used for various applications requiring high safety even during abnormal heat generation, and a battery using the same.

  In conventional batteries, polyethylene and polypropylene microporous membranes that can be wound at low cost are used as separators. These separators have a characteristic that they contract at about 150 ° C. when abnormal heat is generated, and the peripheral edge of the electrode is exposed, which causes a problem of inducing a short circuit between the electrodes.

Moreover, in the conventional wound type battery, the separator is required to have a strength that does not break during winding, and a nonwoven fabric having low tensile strength cannot be used. Therefore, as a separator for a non-aqueous secondary battery, a porous membrane made of an organic polymer that includes a nonwoven fabric sheet and a porous inorganic filler and can swell and retain in an electrolytic solution has been proposed (for example, a patent) Reference 1).
Japanese Patent Laid-Open No. 2003-7279

  However, in the conventional separator such as the porous film disclosed in Patent Document 1 described above, there is a possibility that the separator may contract during abnormal heat generation, although the electrolytic solution holding performance, short-circuit prevention property, mechanical properties, and the like are considered. there were. Although it is possible to enlarge conventional PE or PP microporous membrane separators assuming that they contract more than those of the conventional ones, the contraction rate of these separators is as large as about 20%. If it is assumed that the battery shrinks more than the above, the energy density of the battery will be drastically lowered, so that it cannot be adopted. That is, the increased amount of the separator does not have any useful function at the time of charging / discharging of a normal battery, it merely decreases the weight and volume efficiency, and the energy density is significantly decreased. The current situation is that losing these disadvantages as a price only to show useful work only during abnormal heat generation is not a good idea and is not used.

  In view of the above problems, the present invention provides a separator that prevents shrinkage during abnormal heat generation.

  Furthermore, a second object of the present invention is to contribute to the improvement of battery output by making the separator thinner.

  The present invention is achieved by a separator of a battery, wherein the separator is constituted by a fiber assembly, and the fiber assembly includes fibers having a melting point of 150 ° C. or higher.

  The separator of this invention is comprised with the fiber assembly formed using the fiber whose melting | fusing point is 150 degreeC or more. Therefore, even when the battery is abnormally heated (approx. 200 ° C.), by using a fiber having a melting point of 150 ° C. or higher for the fiber assembly constituting the separator, the battery internal temperature reaches about 200 ° C. Shrinkage of the separator can be effectively prevented. As a result, it is possible to effectively prevent short-circuiting between electrodes of a battery to which the separator is applied.

  The present invention is characterized in that, in a battery separator, the separator is constituted by a fiber assembly, and the fiber assembly includes fibers having a melting point of 150 ° C. or higher. In the present invention, a battery separator can be constituted only by a fiber assembly that does not shrink when the battery is abnormally heated.

  The fiber aggregate that can be used in the separator of the present invention is not particularly limited, and examples thereof include nonwoven fabrics, woven fabrics, knitted fabrics, and combinations thereof.

  The form (shape) of the fiber assembly is not particularly limited as long as it is a form (shape) that can be used as a battery separator, and examples thereof include a sheet shape and a bag shape. That is, a fiber assembly such as a nonwoven fabric sheet, a woven fabric sheet, a knitted fabric sheet, a bag-shaped nonwoven fabric (nonwoven fabric bag), a bag-shaped woven fabric (woven fabric bag), or a bag-shaped knitted fabric (knitted fabric bag) can be used. In particular, a nonwoven fabric sheet and a bag-like nonwoven fabric (nonwoven fabric bag) are advantageous in that the productivity is good and the mass production is possible at a low cost. In the bag-like nonwoven fabric (nonwoven fabric bag), as described in the examples, handling properties are improved and the effect of preventing the displacement between the electrode of the battery element and the separator is also excellent.

  In the present invention, as the material of the fibers constituting the fiber assembly, a material having a high heat resistance having a melting point of 150 ° C. or higher, preferably 240 ° C. or higher is used. In particular, by using a thermosetting resin having a high melting point with a melting point of preferably 150 ° C. or higher, more preferably 240 ° C. or higher as the material of the fiber, a battery with high reliability at the time of abnormality is obtained. When the fiber assembly is composed only of the melting point of the fiber material less than 150 ° C., the function of the separator cannot be performed by melting the fiber, and, similarly to the conventional separator, there is a risk of contraction when the battery is abnormally heated. There is. In addition, since the temperature at the time of abnormal heat generation differs depending on the type of battery, it may be better to use a fiber material having a melting point of 240 ° C. or higher as defined in a preferred range. Depending on the material of the fiber, carbonized at a temperature of 150 ° C. or higher, preferably 240 ° C. or higher (for example, 500 ° C. or higher as in the polyimides shown in Examples 1 and 3) and having no melting point can be used in the present invention. It shall be contained in the fiber whose melting | fusing point is 150 degreeC or more (refer Example 1 and 3).

  The material of the fiber having a melting point of 150 ° C. or higher is not particularly limited, but is preferably a material such as aramid, polyimide, or a related polymer thereof (such as a copolymer with aramid or polyimide). It is desirable to use a resin having high heat resistance. The characteristics of these aramids and polyimide resins are that they do not shrink even when the temperature rises, and carbonize, so the temperature inside the battery is around 200 ° C., and further, a high temperature gas of 400 to 500 ° C. is generated as in the case of gas ejection. Even if it is exposed, it is carbonized without contraction, so that it is extremely useful in that it exhibits a very high separator shape retention function and can effectively suppress contraction of the separator. In addition, these aramids and polyimide fibers are the same as conventional separator materials in terms of chemical resistance, resistance to electrical potential, mechanical properties, electrolyte retention performance, and short circuit prevention required for separators. It has the above excellent characteristics.

It is not necessary to use only fibers having a melting point of the fiber material of 150 ° C. or higher as the fibers constituting the fiber assembly. What is necessary is just to include the minimum which can maintain the shape of a body, and what is necessary is just to contain 10 mass% or more. If the fiber material having a melting point of 150 ° C. or higher is less than 10% by mass, it is difficult to maintain the shape of the fiber assembly at a high temperature during abnormal heat generation.
As the material of the fiber having a melting point of less than 150 ° C. that can constitute the fiber assembly, the chemical reaction stability (reaction inertness), chemical resistance, and potential required for the separator material are applied. Is not particularly limited as long as it has resistance, mechanical properties, electrolytic solution retention performance, short circuit prevention properties, etc., for example, polyethylene (PE), polypropylene (PP), polyamide (nylon), etc. A known resin material for a separator can be used, but preferably an inexpensive resin such as PE or PP can be used.

  The thickness (fiber diameter) of the fibers constituting the fiber assembly is particularly limited as long as it is within a range that does not affect the effect of the present invention to prevent the separator from contracting during abnormal heat generation of the battery. However, in order to contribute to the improvement of battery output by reducing the thickness of the separator, which is the second object of the present invention, the fiber diameter (φ) is usually 5 to 10 μm. It is desirable to use ultrafine fibers of 5 μm or less, preferably 1 to 5 μm. That is, by using ultrafine fibers of φ5 μm or less, a fiber assembly such as a nonwoven fabric (φ1 μm and thickness of about 5 μm) thinner than a nonwoven fabric (thickness of 20 μm to 30 μm) made of conventional fibers (φ5 μm) is produced. Battery output is greatly improved. Also, a fiber assembly is prepared using ultrafine fibers (for example, polyimide fibers) with different thicknesses of φ5 μm or less and conventional fibers (PE, PP fibers) with φ5 μm or more in an appropriate blending ratio. May be.

  The thickness of the separator constituted by the fiber assembly is appropriately determined according to the type and application of the battery, and is not particularly limited, and is usually 5 to 200 μm. Is possible. In addition, in applications such as secondary batteries for driving motors such as electric vehicles (EV), hybrid electric vehicles (HEV), and fuel cell vehicles, it is desired to be 5 to 200 μm, preferably 20 μm or less. When the thickness of the separator is within such a range, it is possible to suppress increase in retention and resistance. In addition, there is an effect of securing mechanical strength in the thickness direction and ensuring high output performance because it is desirable to prevent a short circuit caused by fine particles entering the separator and to narrow the space between the electrodes for high output. . In addition, when a plurality of batteries are connected, the electrode area increases, so that it is desirable to use a thick separator in the above range in order to increase the reliability of the battery. On the other hand, the second object of the present invention is to make the separator thinner and reduce the distance between the electrodes, so that the resistance between them can be further reduced, thereby contributing to the improvement of the battery output. The thickness of the separator is 20 μm or less, preferably 10 to 20 μm. In such a thin film separator, it has been found that if there is dust or burrs on the electrode, it is easy to induce a short circuit, but it has been found that these can be easily and reliably prevented by brushing the electrode surface. That is, even if a thin film separator is used, it can be used without problems such as a short circuit due to dust or burrs. The lower limit of the thickness of the separator is not particularly defined, but is preferably about 10 μm as described above from the viewpoint of handling. On the other hand, when the thickness of the separator exceeds 20 μm, the battery output decreases. However, even when it exceeds 20 μm, it may be used depending on the use of the battery as described above.

  Here, as a separator constituted by a fiber assembly, various forms (shapes) such as a sheet shape and a bag shape by a fiber assembly processed into various forms (shapes) such as a sheet shape as exemplified below. However, the separator is not limited to these. (1) A form in which a sheet-like fiber aggregate is used as a separator as it is, (2) a form in which two or more sheet-like fiber aggregates are laminated or bonded, and used as a separator, (3) as shown in FIGS. Two rectangular sheet-like fiber assemblies 101a and 101b are heat-welded or heat-sealed (for example, aramid fibers or polyimide fibers are heat-sealed) at only a part of the peripheral edge, for example, the corners of the four sides. It is preferable that the temperature is set to about 400 to 600 ° C. so that it is possible to join at the heat welding point 103 and use it as a bag-like separate. (4) Two rectangular sheet-like fiber assemblies A form that is used as a bag-like separate by bonding the whole of the three peripheral edges of the four peripheral edges of the body, or by heat-sealing or heat-sealing, and (5) processed into a bag shape The fiber assembly Form used as Jo separator, and the like. As shown in FIGS. 1A to 1G, the separator 101 is formed into a bag shape (see FIGS. 1B and C), and an electrode (a positive or negative electrode of a non-bipolar electrode, or a bipolar electrode; FIG. 1D shows both surfaces of the current collector 105 In the case where the positive electrode 109 having the positive electrode active material layer 107 formed thereon is housed, the bag-shaped separator 101 sandwiches the electrode 109 (a positive electrode or a negative electrode of a non-bipolar electrode or a bipolar electrode). In this case, the thickness and basis weight of the separator 101 are applied to the separator portions 101a and 101b on one side of the electrode (see FIG. 1g).

The basis weight of the separator constituted by the fiber assembly is one of physical property values represented by the weight per unit area of the separator. The basis weight of the separator is not particularly limited as long as it is within a range that does not affect the effect of the present invention to prevent the separator from contracting when the battery is abnormally heated, and is usually 10 g / m ² or less. Is desirable. When the basis weight of the separator exceeds 10 g / m ² , the retention performance of the electrolytic solution, gel electrolyte, or solid electrolyte may be reduced. Here, the basis weight is not necessarily required to satisfy the above numerical value as long as the separator thickness and the porosity described later are satisfied, and is a numerical value as a guide.

  The porosity of the separator constituted by the fiber assembly is one of physical property values indicating how many holes are formed in the separator. The porosity of the separator is not particularly limited as long as it is within a range that does not affect the effect of the present invention to prevent the separator from contracting during abnormal heat generation of the battery, but from the viewpoint of ion conductivity. Therefore, it is preferably 40% or more. By using a fiber assembly such as a nonwoven fabric having a high porosity and a very low air permeability (≈0) as a separator, the output of the battery is improved. Also, if the porosity is within the above range, the output and reliability can be prevented because of the prevention of output decrease due to the resistance of the electrolyte (electrolyte) and the prevention of short-circuiting due to fine particles penetrating the separator pores (micropores). It has the effect of securing both sexes. When the porosity of the separator is less than 40%, the retention of the electrolyte is deteriorated, and the retention performance of the electrolytic solution, gel electrolyte or solid electrolyte and the output of the battery may be reduced. In addition, the upper limit of the porosity of the separator is desirably 60% or less from the viewpoint of short circuit prevention properties, mechanical properties, and the like. However, even if the porosity of the separator is out of the above range, it may be used because sufficient battery output is obtained depending on the use of the battery. The separator porosity is a value obtained as a volume ratio from the density of the raw material resin and the density of the separator of the final product.

The Gurley value of the separator constituted by the fiber assembly is one of physical property values indicating the permeability of the separator. The Gurley value of such a separator is not particularly limited as long as it does not affect the effect of the present invention to prevent the separator from contracting during abnormal heat generation of the battery, and is usually 10 seconds or less. Is desirable. When the Gurley value of the separator is high, even if the porosity is 40% or more, the movement of ions may be hindered due to, for example, the complexity of the pores. The porosity is 60%. If the mechanical strength is sufficiently maintained below, the lower limit is not limited. However, even if the Gurley value of the separator is out of the above range, it may be used depending on the use of the battery. That is, the current PE or PP porous membrane separator has a Gurley value of usually about 200 to 300 seconds (however, depending on the pore size of the porous membrane separator) from the viewpoint of mechanical properties and short circuit prevention, The permeability is low. The Gurley value of the separator is the air permeability, and indicates the number of seconds that 100 cc of air passes through the membrane at 0.879 g / mm ² pressure in accordance with JIS P8117.

  The bulk density of the separator (particularly the nonwoven fabric separator) constituted by the fiber assembly is not particularly limited as long as sufficient battery characteristics can be obtained by the electrolyte to be impregnated (liquid electrolyte, gel electrolyte, solid electrolyte). It shouldn't be. That is, if the bulk density of the nonwoven fabric separator or the like is too large, the proportion of the non-electrolyte material in the electrolyte layer becomes too large, which may impair the ionic conductivity in the electrolyte layer.

  The fiber assembly constituting the separator of the present invention can be produced by a known nonwoven fabric, woven fabric, or knitted fabric production method. The woven fabric or knitted fabric is woven or knitted on a loom / knitting machine. The method of dripping is widely applicable. Depending on the weaving method, plain weave, twill, misa weave, and knitted fabric can be jacquard or tricot. In addition, the non-woven fabric can be manufactured by, for example, a wet method (for example, a wet papermaking method), a dry method, a spun bond method, a water needle method, or the like. This non-woven fabric is made into a sheet by tens of thousands of yarns extruded from the spinneret, stacked and stacked, to give strength and to fix the fibers by hot pressing, high-pressure water flow method, etc. In the case of a long-fiber non-woven fabric, the fibers are arranged substantially in the longitudinal direction, and there is no yarn corresponding to the weft. In the case of a short-fiber non-woven fabric, the fibers are arranged in the vertical direction by various production methods, and some of them can be manufactured by mixing the vertical and weft yarns by a cross-layer method for a patch or the like. Thus, it can be said that non-woven fabrics are advantageous in that they are highly productive and can be produced in large quantities at low cost. In the case of a short fiber nonwoven fabric, an adhesive is useful for increasing the strength of the nonwoven fabric.

  Next, the battery separator according to the present invention is a battery separator suitably used for various applications that require high safety even during abnormal heat generation, and has high safety even during abnormal heat generation. It can be used widely for various batteries that require

  Therefore, the battery according to the present invention may be any battery characterized by using the separator described above, and the other constituent elements should not be limited at all. By using the separator of the present invention, when the battery abnormally generates heat, the shrinkage of the separator is effectively suppressed, so that the short circuit between the electrodes due to the separator shrinkage can be prevented. Furthermore, in the battery according to the present invention, the separator shrinkage can be effectively suppressed, and the separator can be made thinner, which can greatly contribute to the improvement of the battery output.

  As such a battery, for example, when a battery is distinguished by a usage pattern, it can be applied to any usage pattern of a primary battery and a secondary battery. For example, a secondary battery is suitable for use as a vehicle-mounted power source.

  For example, when the above batteries are distinguished by form / structure, they can be applied to any conventionally known form / structure such as a stacked (flat) battery or a wound (cylindrical) battery. By adopting a stacked (flat) battery structure, long-term reliability can be secured by a sealing technique such as simple thermocompression bonding, which is advantageous in terms of cost and workability. In the present invention, a nonwoven fabric separator that could not be used conventionally due to a problem of tensile strength or a problem of shrinkage during abnormal heat generation can be applied as a battery separator. In a laminated battery, since tensile strength like a wound battery is not required, by using a nonwoven fabric separator composed of a fiber assembly of thermosetting resin fibers having high heat resistance as a laminated battery separator, There is no fear of the separator being pulled during the manufacturing stage, and the battery has high productivity (yield) and high reliability in abnormal conditions.

  When distinguished by battery exterior materials, depending on the intended use and the above-mentioned form / structure, etc., a cylindrical film (exterior) battery often used for wound type, and a polymer-metal laminated film often used for laminated battery The present invention can be applied to any conventionally known form / structure such as a laminate-clad battery represented by (for example, an aluminum laminate film-clad material). In particular, a laminated battery is desirable from the viewpoint of thinning and lightening the battery. On the other hand, from the viewpoint of battery strength, a cylindrical can (exterior) battery is excellent, but even a laminated external battery has, for example, sufficient vibration resistance and impact resistance against vibrations and impacts when mounted on a vehicle. Be able to.

  In addition, when viewed in terms of electrical connection form (electrode structure) in the battery, it can be applied to both non-bipolar (internal parallel connection type) batteries and bipolar (internal series connection type) batteries. . In the bipolar battery, a single cell voltage is higher than that of a normal battery, and a battery having excellent capacity and output characteristics can be configured.

  Moreover, when it distinguishes with the electrolyte layer in a battery, it can apply to all of an electrolyte solution (liquid electrolyte) type battery, a gel electrolyte type battery, and a solid (solid polymer) electrolyte type battery. In the present invention, the above-described separator of the present invention is impregnated with such various electrolytes or electrolyte solutions (including a precursor solution before cross-linking), applied, sprayed (sprayed), etc., and held on the separator, laminated, etc. Can be made. The polymer electrolyte battery is referred to as a gel electrolyte type battery and a solid electrolyte type battery. However, in such a polymer battery, liquid leakage is unlikely to occur, so there is no problem of liquid junction, high reliability, and excellent output characteristics with a simple configuration. This is advantageous in that a battery can be formed. This point is remarkable especially in the solid electrolyte type battery among the polymer batteries.

  When viewed from the electrode material of the battery or metal ions moving between the electrodes, lithium ion secondary battery, sodium ion secondary battery, potassium ion secondary battery, nickel metal hydride secondary battery, ranickel cadmium secondary battery, The nickel-metal hydride battery is not particularly limited, and can be applied to any conventionally known electrode material. A lithium ion secondary battery is preferable. This is because in lithium ion secondary batteries, the cell (single cell layer) voltage is large, high energy density and high output density can be achieved, and it can be suitably used as a driving power source or auxiliary power source for vehicles. This is because it can be sufficiently applied to lithium ion batteries for portable devices such as telephones. Furthermore, since batteries using lithium-transition metal composite oxide as the positive electrode active material are excellent in reactivity, cycle durability, and low cost, these materials can be used in the positive electrode to improve output characteristics. This is advantageous in that an excellent battery can be formed.

  Therefore, in the following description, a non-bipolar laminated laminate-type lithium ion secondary battery using the separator of the present invention (hereinafter also simply referred to as a non-bipolar battery) and a bipolar-type laminated laminate-coated lithium ion battery The secondary battery (hereinafter simply abbreviated as a bipolar battery) will be briefly described with reference to the drawings, but should not be limited to these. That is, there is no limitation on the constituent elements other than the separator described above.

  First, as shown in FIG. 2, in the non-bipolar battery and the bipolar battery 18, both the positive electrode (positive electrode current collector aluminum foil 12 + the coating film 13 of the positive electrode active material layer) and the negative electrode (negative electrode current collector copper foil 15 + negative electrode active material). As shown in FIG. 3, a power generation element (laminated type) 11 in which a coating film 16) of a material layer is laminated so as to face each other through an electrolyte layer 14 formed using the separator of the present invention, For example, a battery that is housed and sealed in an aluminum laminate film pack) 17 is generally used. However, the present invention is not limited thereto. For example, the direction of taking out the positive electrode and negative electrode tabs (reference numerals 12 and 15 in FIG. 3) of the positive electrode current collector aluminum foil and the negative electrode current collector copper foil is as shown in FIG. In this manner, the positive electrode tab 12 and the negative electrode tab 15 may be taken out from the opposite sides (directions).

  Next, FIG. 4 shows a schematic cross-sectional view of a lithium-ion secondary battery (non-bipolar battery) having a non-bipolar laminated laminate exterior using the separator of the present invention. In the non-bipolar battery 31 shown in FIG. 4, by using a laminate film in which a polymer-metal composite is combined with the battery outer packaging material 32, the entire peripheral portion thereof is joined by thermal fusion, whereby the positive electrode current collector 33 is formed. The positive electrode plate (positive electrode) having the positive electrode active material layer 34 formed on both sides, the electrolyte layer 35 formed using the separator of the present invention, and both sides of the negative electrode current collector 36 (one side for the lowermost layer and the uppermost layer of the power generation element) ) Includes a power generation element 38 in which a negative electrode plate (negative electrode) on which a negative electrode active material layer 37 is formed is stacked and sealed. Further, the positive electrode (terminal) lead 39 and the negative electrode (terminal) lead 40 that are electrically connected to the positive electrode plate and the negative electrode plate described above are connected to the positive electrode current collector 33 and the negative electrode current collector 36 of each electrode plate by ultrasonic welding or resistance. It has a structure that is attached by welding or the like and is exposed to the outside of the battery outer packaging material 32 by being sandwiched between the heat fusion portions.

  FIG. 5 is a schematic cross-sectional view schematically showing the entire structure of a bipolar type laminated laminate exterior lithium ion secondary battery (bipolar battery). As shown in FIG. 5, in the bipolar battery 41, a positive electrode active material layer 43 is provided on one side of a current collector 42 composed of one or more sheets, and the negative electrode active material layer of the present invention is provided on the other side. The positive electrode active material 43 and the negative electrode active material layer 44 of the bipolar electrode 45 adjacent to each other with the electrolyte layer 46 formed by using the separator of the present invention between the bipolar electrode 45 provided with 44 are opposed to each other. That is, in the bipolar battery 41, a plurality of bipolar electrodes 45 having the positive electrode active material layer 43 on one surface of the current collector 42 and the negative electrode active material layer 44 on the other surface are disposed via the electrolyte layer 46. The electrode laminate (bipolar battery main body) 47 has a laminated structure. Further, the uppermost layer and the lowermost layer electrodes 45a and 45b of the electrode laminate 47 in which a plurality of such bipolar electrodes 45 and the like are laminated may not have a bipolar electrode structure, and are necessary for the current collector 42 (or terminal plate). A structure in which the positive electrode active material layer 43 or the negative electrode active material layer 44 only on one side may be arranged. In the bipolar battery 41, positive and negative electrode leads 48 and 49 are joined to current collectors 42 at both upper and lower ends, respectively.

  Note that the number of stacked bipolar electrodes 45 (including the electrodes 45a and 45b) is adjusted according to a desired voltage. In addition, since the bipolar battery 41 can contribute to the improvement of battery output by further reducing the thickness of the separator, it is easy to ensure a sufficient output even if the thickness of the entire battery is as thin as possible. This is advantageous in that it can be reduced and the thickness can be further reduced. Further, in the bipolar battery 41 of the present invention, in order to prevent external impact and environmental degradation during use, the electrode laminate 47 portion is made of a battery exterior material (preferably a polymer-metal composite laminate film) 50. The electrode leads 48 and 49 are preferably taken out of the battery exterior material 50 under reduced pressure. The basic configuration of the bipolar battery 41 can be said to be a configuration in which a plurality of stacked single battery layers (single cells) are connected in series. Since this bipolar battery is basically the same as the above-described non-bipolar battery except that the electrode structure is different, each component will be described together below.

[Electrode current collector]
The electrode current collector that can be used in the present invention is not particularly limited, and conventionally known ones can be used. For example, aluminum foil, stainless steel (SUS) foil, nickel-aluminum clad material, copper-aluminum clad material, SUS-aluminum clad material, or a plated material of a combination of these metals can be preferably used. Further, a current collector in which a metal surface is coated with aluminum may be used. Moreover, you may use the electrical power collector which bonded 2 or more metal foil depending on the case. When the composite current collector is used, as a material for the positive electrode current collector, for example, a conductive metal such as aluminum, an aluminum alloy, SUS, or titanium can be used, and aluminum is particularly preferable. On the other hand, as the material of the negative electrode current collector, for example, conductive metals such as copper, nickel, silver, and SUS can be used, and SUS and nickel are particularly preferable. Further, in the composite current collector, the positive electrode current collector and the negative electrode current collector may be electrically connected to each other directly or via a conductive intermediate layer made of a third material. In addition to the flat plate (foil), the positive electrode current collector and the negative electrode current collector are constituted by a lath plate, that is, a plate in which a mesh space is formed by expanding a plate with a cut. Can also be used.

  The thickness of the current collector is not particularly limited, but is usually about 5 to 50 μm. When the current collector is thinned, many cells can be packed in the same volume, so that the capacity per battery volume and the output can be increased. For this reason, reducing the current collector thickness within the above range can provide a battery excellent in both safety and battery performance.

[Positive electrode active material layer]
As a constituent material (also referred to as a positive electrode material) of the positive electrode active material layer, in addition to the positive electrode active material, a conductive material having an electron conductivity, a binder, or the like may be included. Usually, a composite oxide of lithium and a transition metal (lithium-transition metal composite oxide) that is preferably used as a positive electrode active material itself does not have electronic conductivity. Therefore, a conductive material and binder having electronic conductivity. Is used.

The positive electrode active material is not particularly limited, and a positive electrode active material used in a conventionally known lithium ion battery can be used. Specifically, a lithium-transition metal composite oxide can be preferably used. For example, Li · Mn based composite oxides such as spinel LiMn ₂ O ₄ , Li · Co based composite oxides such as LiCoO ₂ , Li · Ni based composite oxides such as LiNiO ₂ , Li ₂ Cr ₂ O ₇ , Li ₂ Li metal oxides such as Li / Cr complex oxides such as CrO ₄ , Li / Fe complex oxides such as LiFeO ₂ and those obtained by substituting some of these transition metals with other elements can be used in combination. However, it is not limited to these materials. These lithium-transition metal composite oxides are excellent in reactivity and cycle durability and are low-cost materials. Therefore, a battery having excellent output characteristics can be formed by using these materials for the electrodes. In addition to these, transition metal and lithium phosphate compounds and sulfuric acid compounds such as LiFePO ₄ ; transition metal oxides and sulfides such as V ₂ O ₅ , MnO ₂ , TiS ₂ , MoS ₂ , and MoO ₃ ; PbO ₂ , AgO, NiOOH, etc. can be used together.

  The average particle diameter of the positive electrode active material is preferably in the range of 0.1 to 20 μm from the viewpoint of increasing the capacity, reactivity, and cycle durability of the positive electrode active material, although it depends on the production method. However, it is not necessarily limited to these ranges. When the positive electrode active material is secondary particles, the average particle size of the primary particles constituting the secondary particles is not particularly limited, but is usually in the range of 0.1 to 5 μm. Is desirable. However, it goes without saying that, depending on the manufacturing method, the positive electrode active material may not be a secondary particle formed by aggregation, agglomeration, or the like. The average particle diameter of the positive electrode active material and the particle diameter of the primary particles can be measured by, for example, observation with a scanning electron microscope or TEM (transmission electron microscope).

  Further, the shape of the positive electrode active material varies depending on the type and manufacturing method, and examples thereof include a spherical shape (powdered shape), a plate shape, a needle shape, a column shape, and a square shape, but are not limited thereto. Any shape can be used without any problems. Preferably, an optimal shape that can improve battery characteristics such as charge / discharge characteristics is appropriately selected. When measuring the average particle diameter of the positive electrode active material as described above, the shape of the particles may not be uniform, so it is expressed by the absolute maximum length. (Through size or mesh path size) may be used. Here, as shown in FIG. 10, the absolute maximum length refers to the one having the maximum length L among the distances between any two points on the contour line of the particle 91.

  The density of the positive electrode active material is determined by the type (composition) and shape (structure) of the positive electrode active material, and can be measured by, for example, a pycnometer.

  The blending amount of the positive electrode active material with respect to the total amount of the positive electrode material is not particularly limited, and is appropriately determined in consideration of usage (output-oriented, energy-oriented, etc.) and ion conductivity.

  The conductive material that can be used for the positive electrode material is not particularly limited, and a conductive material used in a conventionally known lithium ion battery can be used. Specific examples include acetylene black, carbon black, graphite, vapor grown carbon fiber (VGCF), and metal powder material. However, it is not necessarily limited to these.

  The average particle diameter of the conductive material is not particularly limited. In order to achieve high output and high capacity, it is desirable that the thickness be 0.1 μm or less. The lower limit is not particularly defined, but is preferably 1 nm or more from the viewpoint of ease of production. From the viewpoint of ease of handling, the thickness is in the range of about 25 to 50 nm. The average particle diameter of the conductive material can be measured by, for example, SEM observation or TEM observation. Note that when measuring the average particle size of the conductive material described above, the shape of the particles may not be uniform, so the absolute maximum length is used. Size or mesh path size) may be used.

  In addition, the shape of the conductive material varies depending on the type and manufacturing method, and examples thereof include a spherical shape (powdered shape), a plate shape, a needle shape, a column shape, and a square shape, but are not limited thereto. Rather, any shape can be used without problems. Preferably, an optimal shape that can improve battery characteristics such as charge / discharge characteristics is appropriately selected.

  The density of the conductive material is determined by the type (composition) and shape (structure) of the conductive material, and can be measured by, for example, a pycnometer.

  The blending amount of the conductive material with respect to the total amount of the positive electrode material should be determined so that the active material and the conductive material amount have the optimum ratio in consideration of the intended use of the battery (emphasis on output, energy, etc.) and ion conductivity. is there.

  As the binder, polyvinylidene fluoride (PVDF), SBR, polyimide, or the like can be used. However, it is not necessarily limited to these.

  The blending amount of the binder with respect to the total amount of the positive electrode material should be determined in consideration of the intended use of the battery (emphasis on output, emphasis on energy, etc.) and ion conductivity.

  Other positive electrode materials that can be used in the lithium ion secondary battery of the present invention include electrolyte supporting salts (lithium salts), polymer gel electrolytes (host polymers, electrolytes, etc.) for increasing ion conductivity, etc. Can be.

  The polymer gel electrolyte includes a solid polymer electrolyte having ion conductivity and an electrolyte used in a conventionally known non-aqueous electrolyte lithium ion battery, and further has lithium ion conductivity. A structure in which a similar electrolyte solution is held in a non-polymeric skeleton is also included.

Here, the electrolytic solution (electrolyte supporting salt and plasticizer) contained in the polymer gel electrolyte is not particularly limited, and various conventionally known electrolytic solutions can be appropriately used. For example, inorganic acid anion salts such as LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , LiTaF ₆ , LiAlCl ₄ , Li ₂ B ₁₀ Cl ₁₀ , LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, Li (C 2 _F 5 _{SO 2)} selected from organic acid anion salts such as 2 _N, wherein at least one lithium salt (electrolyte support salt), propylene carbonate, cyclic carbonates such as ethylene carbonate; dimethyl carbonate , Chain carbonates such as methyl ethyl carbonate and diethyl carbonate; ethers such as tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane, 1,2-dibutoxyethane; γ-butyrolactone, etc. Lactones; Nitto such as acetonitrile Lyls; Esters such as methyl propionate; Amides such as dimethylformamide; Plasticizers such as aprotic solvents (organic) mixed with at least one selected from methyl acetate and methyl formate Those using a solvent) can be used. However, it is not necessarily limited to these.

  Examples of the solid polymer electrolyte having ion conductivity include known solid polymer electrolytes such as polyethylene oxide (PEO), polypropylene oxide (PPO), and copolymers thereof.

  For example, polyvinylidene fluoride (PVDF), polyvinyl chloride (PVC), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), etc. are used as the polymer having no lithium ion conductivity used in the polymer gel electrolyte. it can. However, it is not necessarily limited to these. Note that PAN, PMMA, etc. are in a class that has almost no ionic conductivity, and therefore can be a polymer having the above ionic conductivity, but here, they are used for a polymer gel electrolyte. This is exemplified as a polymer having no lithium ion conductivity.

As an electrolyte support salt to increase the ionic conductivity, for _{example, LiPF 6, LiBF 4, LiClO} 4, LiAsF 6, LiTaF 6, LiAlCl 4, Li 2 B 10 Cl 10 inorganic acid anion salts such as, Li ( An organic acid anion salt such as CF ₃ SO ₂ ) ₂ N, Li (C ₂ F ₅ SO ₂ ) ₂ N, or a mixture thereof can be used. However, it is not necessarily limited to these.

  The ratio (mass ratio) between the host polymer and the electrolytic solution in the polymer gel electrolyte may be determined according to the purpose of use and the like, and preferably in the range of 2:98 to 90:10, It can be applied even if it falls off.

  The amount of polymer electrolyte (host polymer, electrolyte, etc.), lithium salt, etc. in the positive electrode material of the present invention should be determined in consideration of the intended use of the battery (emphasis on output, energy, etc.) and ion conductivity. is there.

  The coating thickness of the positive electrode active material layer is not particularly limited, and should be determined in consideration of the purpose of use of the battery (output importance, energy importance, etc.) and ion conductivity. The coating thickness of a general positive electrode active material layer is about 20 to 200 μm, and if it is within this range, it can be sufficiently used in the present invention, but the function of the positive electrode material of the present invention can be effectively expressed. Is preferably 30 μm or less. This is because general lithium-ion batteries for consumer use are competing to improve the amount of energy per unit volume, and the thickness of the electrode active material layer tends to increase. The electrolyte layer having the separator of the invention is progressing in the direction of thinning (how much more active material is added and other elements are removed), but in the present invention, these are taken into account. Furthermore, the thickness of the electrode active material layer that generates heat may be determined from the viewpoint of providing a battery having safety in an abnormal state.

[Negative electrode active material layer]
The negative electrode active material layer includes a negative electrode material active material. In addition, conductive materials for increasing electron conductivity, binders, electrolyte supporting salts (lithium salts) for increasing ion conductivity, polymer gels or solid electrolytes (host polymers, electrolytes, etc.), etc. obtain. Except for the type of the negative electrode active material, the content is basically the same as that already described as the “constituent material of the positive electrode active material layer”, and thus the description thereof is omitted here.

  As a negative electrode active material, the negative electrode active material used also in a conventionally well-known solution-type lithium ion battery can be used. Specifically, a negative electrode mainly composed of at least one selected from carbon materials such as natural graphite, artificial graphite, amorphous carbon, coke and mesophase pitch carbon fiber, graphite, and hard carbon which is amorphous carbon. Although it is desirable to use an active material, it is not particularly limited. In addition, a metal oxide (particularly a transition metal oxide, specifically titanium oxide), a composite oxide of a metal (particularly a transition metal, specifically titanium) and lithium, or the like can also be used.

  Furthermore, the electrolyte contained in the negative electrode active material layer may contain a film forming material. Thereby, the capacity | capacitance fall accompanying the charging / discharging cycle of a battery can be suppressed. The film forming material is not particularly limited, and for example, a conventionally known material such as a film forming material described in JP-A-2000-123880 can be used.

  The coating thickness of the negative electrode active material layer is not particularly limited, and should be determined in consideration of the intended use of the battery (output importance, energy importance, etc.) and ion conductivity. The coating thickness of a general negative electrode active material layer is about 20 to 200 μm. If it is within this range, it can be sufficiently used in the present invention, but it is preferably 30 μm or less. This is because general consumer lithium-ion batteries are competing for an improvement in the amount of energy per unit volume, and the coating thickness of the active material layer tends to increase. The electrolyte layer having a separator is progressing in a direction to make it thinner and thinner (how much more active material is added and other elements are removed). The thickness of the electrode active material layer that generates heat may be determined from the viewpoint of providing a battery having safety at the time of abnormality.

[Electrolyte layer]
The electrolyte layer is not particularly limited as long as it is formed using the separator of the present invention, and an electrolyte-containing separator having excellent ion conductivity is used as the electrolyte layer according to the purpose of use. In addition, an electrolyte layer formed by impregnating, applying, spraying, or the like with a polymer gel electrolyte called a polymer electrolyte in a separator can also be suitably used.

(A) Electrolyte-containing separator As an electrolyte that can be soaked in the separator of the present invention, an electrolyte contained in the polymer gel electrolyte in the section of “Constituent material of positive electrode active material layer” of the present invention described above ( Electrolyte salts and plasticizers) can be used, and the description thereof will be omitted. However, if a suitable example of the electrolyte is shown, LiClO ₄ , LiAsF ₆ , LiPF ₅ , LiBOB can be used as the electrolyte. , LiCF ₃ SO ₃ and Li (CF ₃ SO ₂ ) ₂ , and the solvent is ethylene carbonate (EC), propylene carbonate, diethyl carbonate (DEC), dimethyl carbonate, methyl ethyl carbonate, 1,2- Dimethoxyethane, 1,2-diethoxyethane, tetrahydrofuran, 1,3-dioxo The concentration of the electrolyte is adjusted to 0.5 to 2 mol / liter by dissolving at least one kind of ethers consisting of styrene and γ-butyllactone and dissolving the electrolyte in the solvent. The present invention should not be limited to these.

  Since the above-described “separator of the present invention” is used as the separator, description thereof is omitted here.

  However, when a plurality of separators are used in a stacked manner, the separator of the present invention and a conventionally known separator such as PE or PP may be used in a stacked manner as long as the effects of the present invention are not impaired. Good. For example, the separator of the present invention that absorbs and holds the electrolytic solution may be used in combination with a porous sheet made of a polymer that absorbs and holds the electrolytic solution (for example, a polyolefin microporous separator) or an existing nonwoven fabric separator. . This is because the polyolefin microporous separator having the property of being chemically stable with respect to the organic solvent has an excellent effect that the reactivity with the electrolyte (electrolytic solution) can be kept low. Examples of the material of the porous sheet such as the polyolefin-based microporous separator include a laminate having a three-layer structure of PE, PP, and PP / PE / PP. As a material of the existing nonwoven fabric separator, conventionally known materials such as polyolefin such as cotton, rayon, acetate, nylon, polyester, polypropylene, and polyethylene can be used.

  The amount of the electrolytic solution retained by impregnation or the like in the separator may be impregnated or applied to the separator's liquid retention capacity range, but may be impregnated beyond the liquid retention capacity range. For example, in the case of a bipolar battery, resin can be injected into the electrolyte seal portion to prevent the electrolyte solution from leaking out from the electrolyte layer. Therefore, the bipolar battery can be impregnated as long as it can be retained in the separator of the electrolyte layer. . Similarly, in the case of a non-bipolar battery, the battery element can be enclosed in the battery outer packaging material to prevent the electrolyte from leaking out from the inside of the battery outer packaging material. It is. The electrolyte can be impregnated in the separator by a conventionally known method, for example, the electrolyte can be completely sealed after being injected by a vacuum injection method or the like.

(B) Gel electrolyte layer In the gel electrolyte layer of the present invention, the separator of the present invention is impregnated with a polymer gel electrolyte and applied or the like.

  As the polymer gel electrolyte, the same polymer gel electrolyte as that already described in the section “Constituent material of positive electrode active material layer” of the present invention can be used, and the description thereof is omitted here.

  In addition to the electrolyte layer, the polymer gel electrolyte can be included in the positive electrode active material layer and the negative electrode active material layer. In this case, the same polymer gel electrolyte may be used, and differs depending on the layer. A polymer gel electrolyte may be used.

  By the way, a host polymer for a polymer gel electrolyte that is preferably used at present is a polyether polymer such as PEO and PPO. For this reason, the oxidation resistance on the positive electrode side under high temperature conditions is weak. Therefore, when a positive electrode material having a high redox potential is used, the capacity of the negative electrode active material layer is preferably smaller than the capacity of the positive electrode active material layer facing through the polymer gel electrolyte layer. When the capacity of the negative electrode active material layer is smaller than the capacity of the positive electrode active material layer facing, it is possible to prevent the positive electrode potential from being excessively increased at the end of charging. The capacity | capacitance of a positive electrode active material layer and a negative electrode active material layer here can be calculated | required from manufacturing conditions as theoretical capacity | capacitance at the time of manufacturing a positive electrode active material layer and a negative electrode active material layer. You may measure the capacity | capacitance of a finished product directly with a measuring device. However, if the capacity of the negative electrode active material layer is smaller than the capacity of the opposing positive electrode active material layer, the negative electrode potential may be lowered too much and the durability of the battery may be impaired, so it is necessary to pay attention to the charge / discharge voltage. For example, care should be taken not to lower the durability by setting the average charge voltage of one cell (single cell layer) to an appropriate value for the oxidation-reduction potential of the positive electrode active material.

  The thickness of the electrolyte layer constituting the battery is not particularly limited, but is basically about the same as or slightly thicker than the thickness of the separator of the present invention. It is. In order to obtain a compact battery, it is preferable to make it as thin as possible as long as the function as an electrolyte layer can be ensured, and in order to contribute to the improvement of battery output by reducing the thickness as in the case of the separator, the thickness of the electrolyte layer is 15 μm or less, preferably 5 to 10 μm.

  In the present invention, the electrolyte solution of the electrolyte layer may contain various conventionally known additives as long as the effects of the present invention are not impaired.

[Insulation layer]
The insulating layer is mainly used in the case of a bipolar battery. This insulating layer is formed around each electrode for the purpose of preventing adjacent collectors in the battery from contacting each other and short-circuiting due to slight unevenness at the end of the laminated electrode. It is. In this invention, you may provide an insulating layer around an electrode as needed. When this is used as a vehicle driving or auxiliary power source, it is necessary to completely prevent a short circuit (liquid drop) due to the electrolytic solution. Furthermore, vibrations and impacts on the battery are loaded for a long time. Therefore, from the viewpoint of prolonging battery life, it is desirable to install an insulating layer in order to ensure longer-term reliability and safety, and to provide a high-quality, large-capacity power supply. .

  As the insulating layer, any insulating layer may be used as long as it has insulating properties, sealing performance against falling off of the solid electrolyte, sealing performance against moisture permeation from the outside (sealing performance), heat resistance under battery operating temperature, etc. Epoxy resin, rubber, polyethylene, polypropylene, polyimide and the like can be used, but epoxy resin is preferable from the viewpoint of corrosion resistance, chemical resistance, ease of production (film forming property), economy and the like.

[Positive electrode and negative electrode terminal plate]
The positive electrode and the negative electrode terminal plate may be used as necessary. For example, in the case of a bipolar lithium ion battery, depending on the laminated (or wound) structure, the electrode terminal may be directly taken out from the outermost current collector. In this case, the positive electrode and the negative electrode terminal plate are not used. Good.

  When using positive and negative terminal plates, in addition to having a function as a terminal, it is better to be as thin as possible from the viewpoint of thinning, but the laminated electrode, electrolyte and current collector all have mechanical strength. Since it is weak, it is desirable to have strength to sandwich and support these from both sides. Furthermore, it can be said that the thickness of the positive electrode and the negative electrode terminal plate is usually preferably about 0.1 to 2 mm from the viewpoint of suppressing the internal resistance at the terminal portion.

  As materials for the positive electrode and the negative electrode terminal plate, materials used in a conventionally known lithium ion battery can be used. For example, aluminum, copper, titanium, nickel, stainless steel (SUS), and alloys thereof can be used. Aluminum is preferably used from the viewpoints of corrosion resistance, ease of production, economy, and the like.

  The material of the positive electrode terminal plate and the negative electrode terminal plate may be the same material or different materials. Furthermore, the positive electrode and the negative electrode terminal plate may be a laminate of different materials.

[Positive electrode and negative electrode lead]
Regarding the positive electrode and the negative electrode lead, the same lead as that used in a conventionally known lithium ion battery can be used. In addition, the part taken out from the battery exterior material (battery case) does not affect the product (for example, automobile parts, especially electronic devices, etc.) by contacting with peripheral devices or wiring and leaking electricity. It is preferable to coat with a heat-resistant insulating heat-shrinkable tube or the like.

[Battery exterior material (battery case)]
In a lithium ion battery, in order to prevent external impact and environmental degradation during use, the battery stack or the entire battery wound body (see FIGS. 4 and 5), which is a power generation element of the battery, is used as a battery exterior material. Or it is desirable to accommodate in a battery case. From the viewpoint of weight reduction, a polymer-metal composite laminate film in which both surfaces of metals (including alloys) such as aluminum, stainless steel, nickel, and copper are covered with an insulator (preferably a heat-resistant insulator) such as a polypropylene film. It is preferable that the battery stack is housed and sealed by joining a part or all of the peripheral part thereof by heat fusion using a conventionally known battery exterior material. In this case, the positive electrode and the negative electrode lead may be structured to be sandwiched between the heat-sealed portions and exposed to the outside of the battery exterior material. In addition, it is preferable to use a polymer-metal composite laminate film having excellent thermal conductivity because heat can be efficiently transmitted from a heat source of an automobile and the inside of the battery can be quickly heated to the battery operating temperature. The polymer-metal composite laminate film is not particularly limited, and a conventionally known film in which a metal film is disposed between polymer films and the whole is laminated and integrated can be used. As specific examples, for example, an outer protective layer made of a polymer film (laminate outermost layer), a metal film layer, a heat-sealing layer made of a polymer film (laminate innermost layer), and the whole is laminated and integrated. The thing which becomes. Specifically, in the polymer-metal composite laminate film used for the exterior material, a heat-resistant insulating resin film is first formed as a polymer film on both surfaces of the metal film, and heat fusion is performed on at least one heat-resistant insulating resin film. An insulating insulating film is laminated. Such a laminate film is heat-sealed by an appropriate method, whereby the heat-welding insulating film portion is fused and joined to form a heat-sealing portion. An example of the metal film is an aluminum film. Moreover, as said insulating resin film, a polyethylene tetraphthalate film (heat-resistant insulating film), a nylon film (heat-resistant insulating film), a polyethylene film (heat-bonding insulating film), a polypropylene film (heat-bonding insulating film) ) Etc. can be illustrated. However, the exterior material of the present invention should not be limited to these. In such a laminate film, it is possible to easily and surely join one to one (bag-like) laminate films by heat fusion using a heat fusion insulating film by ultrasonic welding or the like. In order to maximize the long-term reliability of the battery, metal films that are constituent elements of the laminate sheet may be directly joined. Ultrasonic welding can be used to join the metal films by removing or destroying the heat-fusible resin between the metal films.

  Next, the battery of the present invention can be widely used for applications that require safety even when abnormal heat is generated. For example, it can be suitably used as a power source for portable electronic devices such as mobile phones and portable personal computers that are required to be safe because they are often carried around, such as being carried in clothes pockets or bags. . Furthermore, as a large capacity power source for electric vehicles (EV), hybrid electric vehicles (HEV), fuel cell vehicles, hybrid fuel cell vehicles, etc., it is suitable for vehicle driving power sources and auxiliary power sources that require high energy density and high output density. Can be used. In this case, it is desirable that the assembled battery is constructed by connecting a plurality of non-bipolar or bipolar lithium ion secondary batteries of the present invention. In other words, in the present invention, a plurality of the lithium ion batteries can be formed into an assembled battery (vehicle submodule) using at least one of a plurality of the lithium ion batteries in parallel connection, series connection, parallel-series connection, or series-parallel connection. This makes it possible to meet the demands for capacity and voltage for various types of vehicles by combining basic batteries. As a result, it becomes possible to facilitate the design selectivity of required energy and output. For this reason, it is not necessary to design and produce different batteries for various vehicles, and it becomes possible to mass-produce basic batteries and to reduce costs by mass production. Hereinafter, a representative embodiment of the assembled battery (vehicle submodule) will be briefly described with reference to the drawings.

  FIG. 6 shows a schematic diagram of an assembled battery (42V1Ah) in which the bipolar battery (24V, 50 mAh) of the present invention is connected in two lines and 20 lines. The tabs in the parallel part were connected by copper bus bars 56 and 58, and the serial part was connected by vibration welding the tabs 48 and 49 together. The ends of the series part are connected to the terminals 62 and 64 to constitute positive and negative terminals. On both sides of the battery, detection tabs 60 for detecting the voltage of each layer of the bipolar battery 41 are taken out, and their detection lines 53 are taken out to the front part of the assembled battery 51. Specifically, in order to form the assembled battery 51 shown in FIG. 6, five bipolar batteries 41 are connected in parallel by the bus bar 56, and two bipolar batteries 41 connected in parallel are connected to each other by electrode tabs in series. These are stacked in four layers and connected in parallel by a bus bar 58 and housed in a metal assembled battery case 55. In this way, by connecting an arbitrary number of bipolar batteries 41 in series and parallel, an assembled battery 51 that can handle a desired current, voltage, and capacity can be provided. In the assembled battery 51, a positive electrode terminal 62 and a negative electrode terminal 64 are formed at the front side of the metal assembled battery case 55. After connecting the batteries in series and parallel, for example, each bus bar 56 and each positive electrode terminal 62. The negative terminal 64 is connected to the terminal lead 59. Further, the assembled battery 51 includes a positive electrode terminal 62 and a negative electrode terminal of a metal assembled battery case 55 for detecting the battery voltage (each cell layer, and further the voltage between terminals of the bipolar battery). 64 is installed at the front of the side surface. All the voltage detection tabs 60 of each bipolar battery 41 are connected to the detection tab terminal 54 via the detection line 53. In addition, an external elastic body 52 is attached to the bottom of the assembled battery case 55, and when a plurality of assembled batteries 51 are stacked to form a composite assembled battery, the distance between the assembled batteries 51 is maintained to prevent vibration. , Impact resistance, insulation, heat dissipation, etc. can be improved.

  In addition to the detection tab terminal 54, the assembled battery 51 may be provided with various measuring devices and control devices depending on the usage. Furthermore, in order to connect the electrode tabs (48, 49) of the bipolar battery 1 or the detection tab 60 and the detection line 53, ultrasonic welding, heat welding, laser welding, electron beam welding, or a rivet is used. You may make it connect using the bus-bars 56 and 58, or using the crimping method. Furthermore, in order to connect the bus bars 56, 58 and the terminal leads 59, etc., ultrasonic welding, heat welding, laser welding, or electron beam welding may be used.

  The external elastic body 52 may be made of the same material as that of the resin group used in the battery of the present invention, but is not limited thereto.

  In addition, the assembled battery of the present invention includes the bipolar battery of the present invention and the non-bipolar battery of the present invention in which the bipolar battery and the positive and negative electrode materials are the same and the voltage is the same by serially arranging the number of constituent units of the bipolar battery. May be connected in parallel. That is, the battery forming the assembled battery may be a mixture of the bipolar battery of the present invention and the non-bipolar battery (however, not all the batteries need to be the battery of the present invention). As a result, an assembled battery that compensates for each other's weaknesses by combining a bipolar battery that focuses on output and a non-bipolar battery that focuses on energy can be achieved, and the weight and size of the assembled battery can be reduced. The proportion of each bipolar battery and non-bipolar battery to be mixed is determined according to the safety performance and output performance required for the assembled battery.

  FIG. 7 shows an assembled battery in which a bipolar battery A (42 V, 50 mAh) and a non-bipolar battery B (4.2 V, 1 Ah) 10 series (42 V) are connected in parallel. The non-bipolar battery B and the bipolar battery A have the same voltage, and a parallel connection is formed at that portion. The assembled battery 51 ′ has a structure in which the bipolar battery A has an output sharing and the non-bipolar battery B has an energy sharing. This is a very effective means in an assembled battery in which it is difficult to achieve both output and energy. Also in this assembled battery 51 ', the tabs of the parallel portion and the non-bipolar battery B adjacent in the horizontal direction in the figure are connected by the copper bus bar 56, and the non-bipolar battery B adjacent in the vertical direction in the figure is connected. The portions connected in series were connected by vibration welding the tabs 39 and 40 together. The ends of the portions where the non-bipolar battery B and the bipolar battery A are connected in parallel are connected to the terminals 62 and 64 to constitute positive and negative terminals. A detection tab 60 for detecting the voltage of each layer of the bipolar battery A is taken out on both sides of the bipolar battery A, and the detection lines (not shown) are taken out at the front part of the assembled battery 51 ′. Therefore, the same members are denoted by the same reference numerals. In detail, in order to form the assembled battery 51 ′ shown in FIG. 7, 10 non-bipolar batteries B were sequentially connected from the end to the bus bar 56 and connected in series. Further, the bipolar battery A and the non-bipolar battery B at both ends connected in series are connected in parallel by the bus bar 56 and housed in a metal battery case 55. In this way, by connecting an arbitrary number of bipolar batteries A in series and parallel, an assembled battery 51 ′ that can handle a desired current, voltage, and capacity can be provided. The assembled battery 50 ′ also has a positive electrode terminal 62 and a negative electrode terminal 64 formed on the front side of the metal assembled battery case 55. After connecting the batteries A and B in series and parallel, for example, Each positive terminal 62 and negative terminal 64 are connected by a terminal lead 59. Further, the assembled battery 51 'has a detection tab terminal 54 made of metal for monitoring battery voltage (voltage of each single battery layer of the bipolar battery A, and voltage between terminals of the bipolar battery A and the non-bipolar battery B). The assembled battery case 55 is installed at the front side of the side surface where the positive electrode terminal 62 and the negative electrode terminal 64 are provided. And all the detection tabs 60 of each bipolar battery A (and non-bipolar battery B) are connected to the detection tab terminal 54 via a detection line (not shown). In addition, an external elastic body 52 is attached to the lower part of the assembled battery case 55, and when a composite assembled battery is formed by stacking a plurality of assembled batteries 51 ′, the distance between the assembled batteries 51 ′ is maintained. In addition, vibration resistance, impact resistance, insulation, heat dissipation, and the like can be improved.

  In the assembled battery of the present invention, the above-described bipolar battery is further connected in series and parallel to form a first assembled battery unit, and the voltage between the terminals of the first assembled battery unit is the same as that of the non-bipolar battery other than the bipolar battery. There is no particular limitation such as forming a second assembled battery unit in which bipolar batteries are connected in series and parallel, and connecting the first assembled battery unit and the second assembled battery unit in parallel to form an assembled battery. .

  The other structural requirements of the assembled battery are not limited at all, and the same structural requirements as those of the assembled battery using the existing non-bipolar battery can be applied as appropriate. Since publicly known components and manufacturing techniques for assembled batteries can be used, description thereof is omitted here.

  Next, at least two or more of the above-mentioned assembled batteries (vehicle submodules) are combined in series, parallel, or in series and parallel to form a combined battery (vehicle assembled battery). It is possible to meet the demand for output relatively inexpensively without producing a new assembled battery. That is, the composite assembled battery of the present invention includes at least two or more assembled batteries (such as those composed only of the bipolar battery or non-bipolar battery of the present invention, or those composed of combinations of bipolar batteries or non-bipolar batteries other than the present invention). It is characterized in that it is connected in series, in parallel, or in series and parallel, and the specification of the assembled battery can be tuned by manufacturing a standard assembled battery and combining it into a composite assembled battery. Thereby, since it is not necessary to manufacture many assembled battery types with different specifications, the composite assembled battery cost can be reduced.

  As the composite battery pack, for example, FIG. 8 is a schematic diagram of the composite battery pack (42V, 6Ah) connected in parallel with the battery pack (42V, 1Ah) 6 using the bipolar battery shown in FIG. Each assembled battery constituting the composite assembled battery is integrated by a connecting plate and a fixing screw, and an anti-vibration structure is formed by installing an elastic body between the assembled batteries. The tabs of the assembled battery are connected by a plate-like bus bar. That is, as shown in FIG. 8, in order to connect the above assembled batteries 51 in parallel to form a composite assembled battery 70, the tabs of the assembled batteries 51 provided on the lid of each assembled battery case 55 ( The positive electrode terminal 62 and the negative electrode terminal 64) are electrically connected using an external positive electrode terminal portion that is a plate-shaped bus bar, an assembled battery positive electrode terminal connecting plate 72 having an external negative electrode terminal portion, and an assembled battery negative electrode terminal connecting plate 74, respectively. To do. Further, a connecting plate 76 having an opening corresponding to the fixing screw hole is fixed to each screw hole (not shown) provided on both side surfaces of each assembled battery case 55 with a fixing screw 77, and The batteries 51 are connected to each other. Moreover, the positive electrode terminal 62 and the negative electrode terminal 64 of each assembled battery 51 are protected by a positive electrode and a negative electrode insulating cover, respectively, and are identified by color-coding into appropriate colors, for example, red and blue. Further, an anti-vibration structure is formed by installing an external elastic body 52 between the assembled batteries 51, specifically, at the bottom of the assembled battery case 55.

  Moreover, in the said composite assembled battery, it is desirable to connect the some assembled battery which comprises this so that attachment or detachment is possible respectively. As described above, in the composite assembled battery in which a plurality of assembled batteries are connected in series and parallel, even if some of the batteries and the assembled battery fail, the repair can be performed only by replacing the failed part.

  The vehicle according to the present invention is characterized in that the assembled battery and / or the composite assembled battery is mounted. This makes it possible to meet a large vehicle demand for space by using a light and small battery. By reducing the battery space, the weight of the vehicle can be reduced.

  As shown in FIG. 9, in order to mount the composite battery pack 70 on a vehicle (for example, an electric vehicle or the like), the composite assembled battery 70 is mounted under a seat (seat) at the center of the vehicle body of the electric vehicle 80. This is because if it is installed under the seat, the interior space and the trunk room can be widened. The place where the battery is mounted is not limited to under the seat, but may be under the floor of the vehicle, behind the seat back, under the rear trunk room, or in the engine room in front of the vehicle.

  In the present invention, not only the composite battery pack but also the battery pack may be mounted on the vehicle depending on the intended use, or the composite battery pack and the battery pack may be mounted in combination. Further, as the vehicle on which the composite assembled battery or the assembled battery of the present invention can be mounted as a driving power source or an auxiliary power source, the above-described electric vehicle, fuel cell vehicle and hybrid vehicle thereof are preferable, but are not limited thereto. It is not a thing. Further, as a vehicle on which the assembled battery and / or the composite assembled battery of the present invention can be mounted as, for example, a driving power supply or an auxiliary power supply, a hybrid vehicle (a gasoline engine and the assembled battery and / or the composite assembled of the present invention is used). A hybrid battery), an electric vehicle, a hybrid electric vehicle, a fuel cell vehicle, a hybrid fuel cell vehicle, and the like are preferable, but not limited thereto.

  Hereinafter, the content of the present invention will be described with reference to examples and comparative examples, but the present invention is not limited to these examples.

Example 1
<Production of battery>
1. Production of Separator In this example, the following polyimide nonwoven fabric sheet was produced as a separator using a wet papermaking method.

Specifically, the material of the fiber is carbonized at 500 ° C. or higher, and a polyimide having no melting point is used. A polyimide fiber having a polyimide fiber thickness (fiber diameter) of 4 μm is obtained by using a wet papermaking method. A sheet-like non-woven fabric (fiber assembly) having characteristics was manufactured and used as a separate of this example. That is, the separator of this example is composed of a polyimide nonwoven fabric sheet (fiber assembly) and has the following characteristics;
Basis weight; 10 g / m ² ,
Thickness: 15 μm,
Porosity: 40%,
Gurley value: 5 seconds / 100 cc.

Here, the Gurley value is the air permeability, and indicates the number of seconds that 100 cc of air passes through the membrane at 0.879 g / mm ² pressure in accordance with JIS P8117.

2. Production of Positive Electrode 100 g of positive electrode active material (LiMn ₂ O ₄ ) and 5 g of conductive material (carbon black) were weighed, 5 g of polyvinylidene fluoride (PVdF) as a binder was added to the above mixture, and mixing was performed with a mixer. Further, an appropriate amount of N-methyl-2-pyrrolidone (NMP) was added as a solvent so that the viscosity became 7000 cP, and the mixture was vacuum-mixed to prepare a slurry.

  Using the slurry prepared as described above, this was coated on an aluminum foil of a positive electrode current collector having a thickness of 15 μm by an applicator, dried by heating at about 80 ° C. with a dryer, and then pressed. The thickness of the positive electrode active material layer was 40 μm (single side).

3. Preparation of Negative Electrode 90% by mass of hard carbon as the negative electrode active material powder, 10% by mass of PVdF as the binder, N-methyl-2-pyrrolidone (NMP) as a solvent was added and stirred to adjust the slurry, and the thickness was measured with an applicator. It apply | coated on the copper foil of a 10 micrometer negative electrode electrical power collector, and after pressing and drying at about 80 degreeC with the dryer, it pressed. The thickness of the negative electrode active material layer was 30 μm (one side).

4). Preparation of Electrolytic Solution The electrolytic solution used was a solution of 1M LiPF ₆ in a mixed solvent of EC (ethylene carbonate): DMC (dimethyl carbonate) = 3: 7 (volume ratio).

5. Production of battery 2. 1. The positive electrode obtained in 1. above. Separator obtained in 1 above, 3. The negative electrode obtained in (1) was sequentially laminated to produce a battery element.

  The battery element is placed in an aluminum laminate film pack, and the above 4. The electrolyte solution obtained in (1) was injected to obtain a laminated laminate-coated lithium ion secondary battery.

<Measurement>
6). Measurement and evaluation of battery performance The laminated laminate-covered lithium ion secondary battery obtained in the above was overheated in a hot box at 150 ° C. while being subjected to constant current discharge (discharge conditions; final voltage 2.5 V).

  As a result, in the laminated laminate outer lithium ion secondary battery using the separator of this example, no internal short circuit was confirmed and no change was observed.

Comparative Example 1
<Production of battery>
1. Production of Separator In this comparative example, a polyethylene microporous membrane was produced using a stretching method as a comparative separator.

The polyethylene microporous membrane separator has the following characteristics:
Basis weight; 9 g / m ² ,
Thickness: 16 μm,
Porosity: 40%,
Gurley value: 200 seconds / 100 cc.

  The production of the positive electrode, the production of the negative electrode, the production of the electrolytic solution, and the production of the battery were the same as in Example 1, and a positive electrode, a negative electrode, an electrolytic solution, and a battery were produced.

  Using the laminated laminate outer lithium-ion secondary battery using the separator of this comparative example, the above measurement item of Example 1 is applied. The same “measurement and evaluation of battery performance” was performed.

  As a result, in the laminated laminate outer lithium ion secondary battery using the separator of this comparative example, an internal short circuit occurred and the separator was contracted.

Example 2
<Production of battery>
1. Production of separator for housing positive electrode Using the two polyimide nonwoven fabric sheets obtained in “Preparation of Separator”, a separator is formed in a bag shape as shown in FIGS. The positive electrode obtained in “Preparation of positive electrode” was accommodated. Thereby, handling was improved.

2. Production of Negative Electrode and Electrolytic Solution The production of the negative electrode and the electrolytic solution was performed in the same manner as in Example 1 to produce a negative electrode and an electrolytic solution.

3. Production of Battery Example 1-5. In the same manner as in “Battery preparation”, 1. 1. A separator that accommodates the positive electrode obtained in 1 above. The negative electrode obtained in (1) was sequentially laminated to produce a battery element.

  Place the battery element in an aluminum laminate film pack, and The electrolyte solution obtained in (1) was injected to obtain a laminated laminate-coated lithium ion secondary battery.

<Measurement>
4). Measurement and evaluation of battery performance 6. Using the laminated laminate exterior lithium ion secondary battery using the bag-shaped separator of this example, the measurement item of Example 1 described above was performed. The battery performance was measured and evaluated in the same manner as above.

  As a result, although it heated to 150 degreeC with the hot box, the internal short circuit was not confirmed and the change was not seen.

Example 3
<Production of battery>
1. Production of Separator In this example, the following polyimide-containing nonwoven fabric sheet was produced using a wet papermaking method as a separator.

Specifically, the material of the fiber used was polyimide that was carbonized at 500 ° C. or higher and had no melting point, and PE, PP, and nylon (polyamide). Under the present circumstances, it mix | blended so that content of the polyimide fiber of a nonwoven fabric might be 10 mass%, 30 mass% of other PE fibers, 30 mass% of PP fibers, and 30 mass% of nylon fibers. Further, the thickness (fiber diameter) of each fiber was 4 μm for polyimide fiber, 5 μm for PE fiber, 5 μm for PP fiber, and 5 μm for nylon fiber. A sheet-like nonwoven fabric (fiber assembly) having the following characteristics was produced from each of these fibers using a wet papermaking method, and used as a separate of this example. That is, the separator of this example is composed of a nonwoven fabric sheet (fiber assembly) containing 10% by mass of polyimide and has the following characteristics;
Basis weight; 10 g / m ² ,
Thickness: 17 μm,
Porosity: 38%,
Gurley value: 6 seconds / 100 cc.

  The merit of the separator obtained in this example is large in cost. That is, polyimide fibers are expensive compared to existing PE and PP fibers, so use only the minimum amount of polyimide fiber that can maintain its shape under high temperatures during abnormal heat generation, and other inexpensive fibers such as PE and PP. Can be used to produce a low-cost separator. In addition, as described above, it is extremely useful because the effect of “shutdown phenomenon” by other fibers can be obtained while suppressing shrinkage of the separator during abnormal heat generation.

  The production of the positive electrode, the production of the negative electrode, the production of the electrolytic solution, and the production of the battery were the same as in Example 1, and a positive electrode, a negative electrode, an electrolytic solution, and a battery were produced.

  Using the laminated laminate outer lithium-ion secondary battery using the separator of this example, the above measurement item of Example 1 was applied. The same “measurement and evaluation of battery performance” was performed.

  As a result, in the laminated laminate exterior lithium ion secondary battery using the separator of this example, it was heated to 150 ° C. in a hot box, but an internal short circuit was not confirmed and no change was observed.

It is the plane schematic which partially overlapped and represented two square sheet-like fiber assemblies (nonwoven fabric) prepared in order to produce a bag-shaped separator. FIG. 1B is a schematic plan view schematically showing a state of a bag-like separator produced by stacking and heat-sealing two rectangular sheet-like fiber assemblies (nonwoven fabrics) prepared in FIG. 1A. It is the XX sectional schematic drawing of FIG. 1B. It is the plane schematic which represented typically the mode of the positive electrode prepared in order to accommodate in the bag-shaped separator of FIG. 1B and C. It is the YY line cross-sectional schematic of FIG. 1D. 1B is a schematic plan view schematically showing a state in which the positive electrode of FIGS. 1D and 1E is stored in the bag-shaped separator of FIGS. 1B and 1C. FIG. It is a ZZ line section schematic diagram of Drawing 1F. It is the schematic perspective view which represented typically the electric power generation element (1 layer) which laminated | stacked the positive electrode and negative electrode of this invention so that it might oppose through an electrolyte layer. It is the schematic perspective view which represented typically a mode that the laminated battery element created by the Example and the comparative example was accommodated in the aluminum laminate exterior (aluminum laminate film pack), and was sealed. The cross-sectional schematic of the lithium ion secondary battery (non-bipolar battery) of the laminated laminate exterior which is not a bipolar type | mold which uses the separator of this invention is shown. BRIEF DESCRIPTION OF THE DRAWINGS The schematic sectional drawing which represented typically the whole structure of the bipolar type lamination | stacking lamination | stacking exterior lithium ion secondary battery (bipolar battery) using the separator of this invention is shown. It is a schematic diagram which shows an example of the assembled battery which connected the bipolar battery of this invention in 2 series 20 parallel. 6A is a plan view of the assembled battery, FIG. 6B is a front view of the assembled battery, FIG. 4C is a right side view of the assembled battery, and FIG. In (c), all show the inside of the assembled battery through the outer case so that it can be seen that the bipolar batteries are connected in series and in parallel. It is a figure which shows an example of the assembled battery which connected the bipolar battery A and non-bipolar battery B10 series of this invention in parallel. FIG. 7A is a plan view of the assembled battery, FIG. 7B is a front view of the assembled battery, and FIG. 7C is a right side view of the assembled battery. In (c), all show the inside of the assembled battery through the outer case so that it can be seen that the bipolar battery A and the non-bipolar battery B are connected in series and in parallel. It is a figure which shows an example of the composite assembled battery of this invention. FIG. 8A is a plan view of the composite battery pack, FIG. 8B is a front view of the composite battery pack, and FIG. 8C is a right side view of the composite battery pack. It is a schematic diagram which shows the electric vehicle of the state which mounts a composite assembled battery. It is explanatory drawing explaining the absolute maximum length used when measuring the particle size of particle | grains.

Explanation of symbols

101 separator,
101a, 101b A rectangular sheet-like fiber assembly,
103 heat welding point,
105 current collector,
107 positive electrode active material layer,
109 positive electrode,
11 A power generation element (one layer) in which a positive electrode and a negative electrode are laminated via an electrolyte layer,
12 Positive electrode current collector (aluminum foil, etc.)
13 Positive electrode active material layer (coating film thereof),
14 electrolyte layer (electrolyte impregnated separator, etc.),
15 Negative electrode current collector (copper foil, etc.)
16 negative electrode active material layer (coating film thereof),
17 Aluminum laminated film pack,
18 batteries,
31 non-bipolar battery,
32 Battery exterior material,
33 positive electrode current collector,
34 positive electrode active material layer,
35 electrolyte layer,
36 negative electrode current collector,
37 negative electrode active material layer,
38 Power generation elements,
39 Positive electrode (terminal) lead,
40 Negative electrode (terminal) lead,
41 bipolar battery,
42 current collector,
43 positive electrode active material layer,
44 negative electrode active material layer,
45 bipolar electrodes,
45a, the uppermost electrode of the electrode stack,
45b, the bottom electrode of the electrode stack,
46 electrolyte layer,
47 electrode laminate (bipolar battery body, power generation element),
48 positive lead,
49 Negative lead,
50 Battery exterior material (exterior package),
51, 51 'battery pack,
52 external elastic body,
53 detection lines,
54 detection tab terminal,
55 battery pack case,
56, 58 Busbar,
59 Terminal lead,
62 positive terminal,
64 negative terminal,
70 composite battery pack,
72 composite battery positive electrode terminal connecting plate,
74 composite battery negative electrode terminal plate,
76 connecting plate,
77 fixing screws,
80 electric car,
91 particles (including irregular particles)
L Maximum length.

Claims (7)

In battery separators,
The separator is composed of a fiber assembly,
The fiber assembly is not fibrillated, a resin fiber containing more than 10 wt% aramid fibers and / or polyimide fibers,
The porosity of the separator is 38-60%,
A separator having a thickness of 20 μm or less. The separator according to claim 1, wherein the fibers constituting the fiber assembly have a fiber diameter of 5 μm or less. The separator according to claim 1 or 2 , wherein the battery is a laminated laminate battery. The battery separator according to any one of claims 1 to 3, characterized in that a lithium ion secondary battery. The separator according to any one of claims 1 to 4 , wherein the separator has a thickness of 10 to 20 µm. Cell characterized by comprising using a separator according to any one of claims 1-5. The battery according to claim 6 , wherein the separator is formed in a bag shape and houses the positive electrode.

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