JP2006179205A - Nonaqueous electrolytic solution battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte battery which has superior safety even in the case of an emergency such as an overcharge and inner short circuit, and which has superior rapid charging characteristics. <P>SOLUTION: This is a nonaqueous electrolyte battery which is provided with a cathode having an active material containing a layer that contains an active material capable of storing and releasing lithium ions on one face or both faces of a current collector, an anode containing an active material capable of storing and releasing lithium ions, and an ion permeable insulation layer interposed between the cathode and the anode, in which a capacity per a unit volume of the active material containing layer in the cathode is 250 mAh/cm<SP>3</SP>or more, and in this nonaqueous electrolyte battery when charging is carried out under a condition that total charge time is 10 minutes, of which the charge time at a current value of 5 C or more is 8 minutes or more, a charged amount reaches 80% or more of the totally charged amount where charging is carried out under a constant current at 0.2 C up to 4.2 V, and then charging is continued under a constant voltage at 4.2 V up to the total charge time becomes 7 hours, and which does not ignite fire even if charging is carried out for an hour under a condition of 6 C and 15 V. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a non-aqueous electrolyte battery, and more particularly to a non-aqueous electrolyte battery that is particularly suitable for use as a power source for portable electronic devices, electric vehicles, road leveling, etc., and that is excellent in safety. is there.

  Lithium ion batteries, which are a type of non-aqueous battery, are widely used as power sources for portable devices such as mobile phones and notebook personal computers because of their high energy density. However, the lithium ion battery has a problem that the output density is inferior to that of an alkaline electrolyte secondary battery such as a nickel cadmium battery or a nickel metal hydride battery, and further, it is disadvantageous in terms of rapid charge and rapid discharge characteristics.

  In order to solve the problems in the lithium ion battery as described above, the positive electrode active material is made into fine particles (Patent Document 1), the thickness of the active material layer is decreased (Patent Documents 2 and 3), and activated carbon which is an electrode material Techniques such as compounding (Patent Documents 4 and 5) have been proposed.

JP 2004-311297 A JP 11-329409 A JP 2001-118569 A JP 2004-178828 A JP 2004-296431 A

  However, the techniques of Patent Documents 1 to 5 are intended to improve the output density, and for example, sufficient studies have not been made on the quick charge characteristics and safety.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a nonaqueous electrolyte battery that is excellent in safety at the time of abnormality such as overcharge and internal short circuit and also excellent in quick charge characteristics. .

  The non-aqueous electrolyte battery of the present invention that has achieved the above object is a positive electrode having an active material containing layer containing an active material capable of occluding and releasing lithium ions on one or both sides of a current collector, and occluding and releasing lithium ions. A nonaqueous electrolyte battery comprising a negative electrode containing a possible active material, and an ion-permeable insulating layer interposed between the positive electrode and the negative electrode, which satisfies the following requirement (1) or (2) It is characterized by this.

(1) The capacity per unit volume of the active material-containing layer in the positive electrode is 250 mAh / cm ³ or more, the total charging time is 10 minutes, and the charging time at a current value of 5 C or more is 8 minutes or more. The charging capacity when charging under conditions is constant current charging to 4.2 V at 0.2 C, then constant voltage charging at 4.2 V, and the charging capacity when the total charging time is 7 hours is 80 %, And it does not ignite even if it is charged for 1 hour under conditions of 6C and 15V.

  (2) The thickness of the active material-containing layer in the positive electrode is 30 μm or less, and the thickness of the ion-permeable insulating layer is equal to or greater than the thickness of the active material-containing layer in the positive electrode.

In the nonaqueous electrolyte battery that satisfies the requirement (1), the thickness of the active material-containing layer in the positive electrode is preferably 30 μm or less. In addition, in the nonaqueous electrolyte battery that satisfies the requirement (2), it is recommended that the capacity per unit volume of the active material-containing layer in the positive electrode is 250 mAh / cm ³ or more.

  As will be described later, in the battery of the present invention, the positive electrode and the negative electrode are preferably used as a laminated electrode body laminated with an ion-permeable insulating layer or as a wound electrode body wound further. In such an electrode body, there may be a plurality of active material-containing layers and ion-permeable insulating layers in the positive electrode. In the present invention, the “thickness of the active material-containing layer in the positive electrode” refers to the active material formed on the current collector in the structural unit when the pair of positive electrode, ion-permeable insulating layer, and negative electrode are used as the structural unit. The thickness of the substance-containing layer from the current collector surface to the ion-permeable insulating layer, and “the thickness of the ion-permeable insulating layer” is the thickness of the ion-permeable insulating layer between the positive electrode and the negative electrode in the structural unit. It is thickness. In addition, the thickness of the active material-containing layer and the thickness of the ion-permeable insulating layer in the present invention are thicknesses measured using a thickness gauge (“ID-C112” manufactured by Mitutoyo Corporation).

  According to the present invention, it is possible to provide a non-aqueous electrolyte battery that suppresses ignition in the event of an abnormality such as overcharge or internal short circuit, has good safety, and excellent quick charge characteristics.

The first aspect of the nonaqueous electrolyte battery of the present invention is the point having the requirement (1) above, that is, the capacity per unit volume of the active material-containing layer in the positive electrode is 250 mAh / cm ³ or more, The total charging time is 10 minutes, and the charging capacity when charging under the condition that the charging time at a current value of 5C or more is 8 minutes or more is constant current charging to 4.2V at 0.2C. .Characteristic in that it is 80% or more of the charging capacity when charging at a constant voltage of 2V and the total charging time is 7 hours, and it does not ignite even if it is charged for 1 hour under the conditions of 6C and 15V. Have.

In the first aspect of the present invention, it is required that the capacity per unit volume of the active material-containing layer in the positive electrode is 250 mAh / cm ³ or more because it is a basic characteristic (high energy) as a nonaqueous electrolyte battery. This is to ensure the density). As for the capacity | capacitance per unit volume of the said active material content layer, it is more preferable that it is 400 mAh / cm < ³ > or more. The capacity per unit volume of the active material-containing layer is preferably 750 mAh / cm ³ or less.

  In the first aspect of the present invention, the total charging time is 10 minutes, and when charging at a current value of 5 C or more is 8 minutes or more [“charging condition (A)”. ] When the charging capacity is constant current charging to 4.2 V at 0.2 C, then constant voltage charging at 4.2 V, and the total charging time is 7 hours ["Charging condition (B)"] 80% or more of the charge capacity.

  That is, the charging condition (B) is a condition of charging so as to satisfy the capacity of the battery as much as possible over a relatively long time, while the charging condition (A) is 10 minutes. It is a charging condition in a short time. The larger the above-mentioned ratio, that is, the ratio of the charging capacity in the charging condition (A) to the charging capacity in the charging condition (B) (%, hereinafter may be referred to as “rapid charging capacity ratio”), the battery It is shown that the characteristics that can essentially charge the capacity of the battery can be charged in a short time, that is, the quick charge characteristics are excellent. The rapid charge capacity ratio is more preferably 85% or more.

  In addition, the nonaqueous electrolyte battery of the present invention is excellent in safety at the time of abnormality such as overcharge. Specifically, the battery according to the first aspect of the present invention does not ignite even when charging under conditions of 6 C and 15 V, that is, overcharging for 1 hour.

  Furthermore, in the 1st aspect of this invention, it is preferable that the thickness of the said active material content layer in a positive electrode is 30 micrometers or less. When the active material-containing layer has such a thickness, it is easy to improve the quick charge characteristics of the battery, and the output density of the battery can be increased.

  In the first aspect of the present invention, the thickness of the ion-permeable insulating layer is preferably equal to or greater than the thickness of the active material-containing layer in the positive electrode, and is 1.5 times the thickness of the active material-containing layer. More preferably. By adopting such a configuration, it becomes easy to ensure the safety of the battery (details will be described later in the description of the second aspect). The thickness of the ion-permeable insulating layer is desirably 5 times or less the thickness of the active material-containing layer. If the active material-containing layer is too thick, problems such as a decrease in energy density and an increase in internal resistance may occur.

  The nonaqueous electrolyte battery having the characteristics according to the first aspect can be obtained, for example, by adopting the configuration according to the second aspect described later.

  The second aspect of the nonaqueous electrolyte battery of the present invention is the point having the requirement (2) above, that is, the thickness of the active material-containing layer in the positive electrode is 30 μm or less, and the ion-permeable insulating layer. Is characterized in that the thickness is equal to or greater than the thickness of the active material-containing layer in the positive electrode.

As a positive electrode material (positive electrode active material) of a lithium ion battery such as the nonaqueous electrolyte battery of the present invention, a composite oxide of lithium and a transition metal such as LiCoO ₂ or LiMn ₂ O ₄ is usually used. These active materials are usually used in the form of crystal particles, for example, a slurry-like composition together with a carbonaceous conductive aid, binder, etc., and the composition is applied to the surface of a current collector such as an aluminum foil. An active material-containing layer is formed by coating.

  In such a nonaqueous electrolyte battery, when charging with a relatively large current value in a short time, the charging involves a battery reaction in the vicinity of the electrode surface (active material-containing layer surface). When the thickness of the active material-containing layer is large, charging is difficult to be achieved in the vicinity of the current collector. Therefore, from the viewpoint of improving the quick charge characteristics of the nonaqueous electrolyte battery, for example, it is preferable to thin the active material-containing layer in the positive electrode. By adopting such a configuration, when charging is performed in a short time with a relatively large current value, the ratio of active materials that can participate in charging is increased, and the above-mentioned rapid charging capacity ratio is improved. Can do.

  However, the active material-containing layer in the positive electrode cannot be made thinner than the particle size of the active material crystal particles. Moreover, when the crystal particles approach the thickness of the active material-containing layer, the thickness unevenness of the active material-containing layer increases, and a protrusion is generated on the electrode surface (active material-containing layer surface). In this case, the separator that is interposed between the positive electrode and the negative electrode and serves as an insulating layer is likely to be damaged by the protrusions on the surface of the positive electrode, thereby causing a short circuit. In order to avoid such problems, it is necessary to make the positive electrode active material crystal particles smaller and finer. However, when such fine particles are used, the specific surface area of the active material, and thus the specific surface area of the positive electrode surface. Becomes too large to cause a rapid reaction in the event of an abnormality such as overcharge or internal short circuit, making it difficult to ensure the safety of the battery.

  Therefore, in the second aspect of the present invention, in addition to reducing the thickness of the active material-containing layer in the positive electrode in order to improve the quick charge characteristics, the ions are interposed between the positive electrode and the negative electrode and serve as a separator. The safety of the battery is also improved by setting the thickness of the transparent insulating layer to be equal to or greater than the thickness of the active material-containing layer.

  That is, in the second aspect of the present invention, the thickness of the active material-containing layer in the positive electrode is 30 μm or less. When the thickness of the active material-containing layer is too large, it becomes difficult to obtain a battery having excellent quick charge characteristics. In addition, the output density of the battery also decreases. The thickness of the active material-containing layer is preferably 15 μm or less. In addition, the lower limit of the thickness of the active material-containing layer is desirably 2 μm. It is recommended that the thickness of the active material-containing layer be selected so that the thickness ratio with the ion-permeable insulating layer satisfies the above-mentioned relationship while satisfying the above value.

  Further, in the second aspect of the present invention, the thickness of the ion-permeable insulating layer is not less than the thickness of the active material-containing layer in the positive electrode, and more preferably not less than 1.5 times the thickness of the active material-containing layer. preferable. By controlling the relationship between the thickness of the ion-permeable insulating layer and the thickness of the active material-containing layer in this way, the insulating layer is damaged by the active material, the particle size of the active material particles is small, and the ratio of the positive electrode When the surface area is large, the rapid reaction that can occur at the time of abnormality can be suppressed, and the safety of the battery can be improved. The thickness of the ion permeable insulating layer is desirably 5 times or less the thickness of the active material-containing layer in the positive electrode.

Further, in the second aspect of the present invention, the capacity per unit volume of the active material-containing layer in the positive electrode (capacity density), it is preferably 250 mAh / cm ³ or more and 400 mAh / cm ³ or more More preferred. When the capacity density of the active material-containing layer is such a value, the battery can be increased in energy density, so that a battery having a high output density and a high energy density can be obtained. That is, when the capacity density of the active material-containing layer is too small, the output density of the battery becomes small. In addition, the upper limit of the capacity density of the active material-containing layer is desirably 700 mAh / cm ³ .

  Next, in the configuration of the nonaqueous electrolyte battery of the present invention, matters common to the first aspect and the second aspect will be described in detail.

The positive electrode according to the nonaqueous electrolyte battery of the present invention is obtained by forming an active material-containing layer containing a positive electrode active material capable of occluding and releasing lithium ions on one side or both sides of a current collector. As the positive electrode active material, for example, Li _1-x M _1-y O ₂ (-0.1 <x <0.1, -0.1 <y <0.1, M: Co, Ni, Mn, etc. Li-containing transition metal oxide having a layered structure represented by: LiMn ₂ O ₄ or other lithium manganese oxide; Li _{1 + x} Mn _2−xy M in which a part of Mn of LiMn ₂ O ₄ is substituted with another element _y O ₄ (0 ≦ x ≦ 0.1, 0 ≦ y ≦ 0.3); olivine type LiMPO ₄ (M: Co, Ni, Mn, Fe); LiMn _0.5 Ni _0.5 O ₂ ; Li _{( 1 + a)} Mn _x Ni _y Co _(1-xy) O ₂ (−0.1 <a <0.1, 0 <x <0.5, 0 <y <0.5); Is possible. A positive electrode mixture in which a known conductive additive (carbon material such as carbon black or acetylene black) or a binder such as polyvinylidene fluoride (PVDF) is appropriately added to these positive electrode active materials, and a current collector as a core As the material, a finished product (active material-containing layer) or the like can be used as the positive electrode.

  As for the particle size of the positive electrode active material, the maximum particle size needs to be equal to or less than the thickness of the active material-containing layer. For example, those having an average particle size of 0.1 to 5 μm are preferably used. Moreover, it is more preferable that the particle diameter of the positive electrode active material is ¼ or less of the thickness of the active material-containing layer. If the particle size is too small, the specific surface area of the active material may become too large, and the effect of improving the safety of the battery may be reduced. If the particle size is too large, the surface roughness of the active material-containing layer will increase, and It becomes difficult to maintain insulation between the negative electrodes. In addition, the active material can be combined with a conductive agent as appropriate. Such compounding can be performed by a conventionally known method (for example, a method disclosed in JP-A No. 2004-178828 or JP-A No. 11-283612).

  As the positive electrode current collector, for example, an aluminum foil, a punching metal, a net, an expanded metal, or the like can be used. However, an aluminum foil having a thickness of 10 μm to 30 μm is preferably used. If the thickness is too small, the strength of the foil is too low and handling becomes difficult. If the thickness is too large, the proportion of the foil in the battery becomes too large and the energy density decreases.

  The active material-containing layer in the positive electrode is formed by, for example, applying a composition (paste, slurry, etc.) containing the positive electrode active material, the conductive auxiliary agent, the binder, and the dispersion medium to the surface of the positive electrode current collector. It can be formed by drying. Examples of the dispersion medium that can be used in the composition for forming an active material-containing layer include N-methyl-2-pyrrolidone (NMP), water, toluene, and the like. In the composition for forming an active material-containing layer, a part of the components may be dissolved in the dispersion medium. As a method of applying the active material-containing layer forming composition to the current collector, for example, a coating method using various coaters such as a die coater, a curtain coater, a spray coater, a gravure coater, a flexo coater, and a knife coater can be employed. . Moreover, as a drying method and conditions after application | coating of the said composition, passing for 2 to 20 second in 100-120 degreeC warm air is mentioned, for example. In addition, after drying, the thickness of the active material-containing layer can be adjusted by calendaring or the like.

  The lead portion on the positive electrode side is usually provided by leaving an exposed portion of the current collector without forming an active material-containing layer on a part of the current collector when forming the positive electrode, and using that as the lead portion. However, the lead portion is not necessarily integrated with the current collector from the beginning, and may be provided by connecting an aluminum foil or the like to the current collector later.

  The negative electrode according to the present invention is not particularly limited as long as it contains an active material capable of occluding and releasing lithium ions and is a negative electrode used in a conventionally known nonaqueous electrolyte battery (lithium ion battery). . For example, carbon that can occlude and release lithium, such as graphite, pyrolytic carbons, cokes, glassy carbons, fired organic polymer compounds, mesocarbon microbeads (MCMB), and carbon fibers as active materials One type or a mixture of two or more types of system materials is used. In addition, elements such as Si, Sn, Ge, Bi, Sb, In and their alloys, lithium-containing nitrides, oxides and other compounds that can be charged and discharged at a low voltage close to lithium metal, or lithium metals and lithium / aluminum alloys Can also be used as a negative electrode active material. A negative electrode mixture obtained by appropriately adding a conductive additive (carbon material such as carbon black) or a binder such as PVDF to these negative electrode active materials is formed into a molded body (negative electrode active material-containing layer) using a current collector as a core material. In addition, the above-mentioned various alloys and lithium metal foils may be used alone or formed as a negative electrode active material-containing layer on a current collector.

  When a current collector is used for the negative electrode, a copper or nickel foil, a punching metal, a net, an expanded metal, or the like can be used as the current collector, but a copper foil is usually used. The thickness of the negative electrode current collector is desirably 6 to 30 μm. If the current collector is too thin, its strength becomes too weak and difficult to handle, and if it is too thick, the volume ratio occupied by the current collector in the battery increases, and the energy density of the battery decreases.

  When the electrode is used as a negative electrode, the active material-containing layer formed of the negative electrode mixture is a composition containing a negative electrode active material, a binder, a solvent, a dispersion medium, or the like (a paste, a slurry, etc. ) Is applied to the surface of the negative electrode current collector and dried. Examples of the solvent or dispersion medium that can be used in the composition for forming an active material-containing layer include water, NMP, toluene, and the like. As a method for applying the active material-containing layer forming composition to the current collector, the same method as the method using various coaters described as the method for applying the positive electrode active material-containing layer forming composition can be employed. Moreover, as a drying method and conditions after application | coating of the said composition, passing for 2 to 20 second in 100-120 degreeC warm air is mentioned, for example. In addition, after drying, the thickness of the active material-containing layer can be adjusted by calendaring or the like.

  The lead part on the negative electrode side, like the lead part on the positive electrode side, usually leaves an exposed part of the current collector without forming a negative electrode active material-containing layer on a part of the current collector during the preparation of the negative electrode. The lead portion is provided. However, the negative electrode side lead portion is not necessarily integrated with the current collector from the beginning, and may be provided by connecting a copper foil or the like to the current collector later.

  The ion-permeable insulating layer according to the present invention is interposed between the positive electrode and the negative electrode and serves as a separator.

  The ion-permeable insulating layer is not particularly limited as long as it has ion permeability for battery reaction and insulation that can prevent a short circuit between the positive electrode and the negative electrode. For example, independent ion-permeable properties such as microporous membranes made of resin such as polyolefin (polyethylene, polypropylene, etc.) used in conventionally known lithium ion batteries (for example, “E16MMS” manufactured by Tonen Chemical Nasu Co., Ltd.) A membrane can be used. More preferably, it is an ion-permeable insulating layer formed on the surface of the positive electrode and / or the negative electrode and integrated with the positive electrode and / or the negative electrode (hereinafter, the positive electrode and the negative electrode may be collectively referred to as “electrode”). . As such an ion-permeable insulating layer, for example, a composition containing organic or inorganic fine particles is applied to the electrode surface as disclosed in WO98 / 38688 pamphlet or JP-A-10-163075. As formed, as disclosed in Japanese Patent No. 3371839, Japanese Patent Laid-Open No. 11-86844, and Japanese Patent Laid-Open No. 2004-2658, after applying a solution containing a resin to the electrode surface, After replacing the solution solvent with a solvent, or mixing the resin solution with a substance that can be dissolved in a specific solvent that cannot dissolve the resin, applying this to the electrode surface to form a layer, What is made porous by dissolving the substance with a solvent, etc. can be used. Moreover, after forming the same (layer) as the ion-permeable insulating layer integrated with the electrode on the substrate surface instead of the electrode surface, it is peeled off from the substrate surface to obtain an independent film, This can also be used as an ion-permeable insulating layer.

  When the ion-permeable insulating layer is integrated with the electrode, the insulating layer may be formed on any surface of the positive and negative electrodes, but in order to ensure good insulation, the wider one is used. It is desirable to form on the electrode surface. Normally, in order to avoid dendrite generation due to charge concentration at the electrode end face, the width of the negative electrode is made slightly wider than the positive electrode, but in such a case, it is formed on the negative electrode surface. desirable. Further, an ion permeable insulating layer may be formed on both the positive electrode and the negative electrode, or a method such as hot pressing after laminating or winding the positive electrode, the negative electrode and the ion permeable insulating layer (each of the above independent films). May be integrated.

  In view of the surface roughness of the electrode, the thickness of the ion-permeable insulating layer is desirably, for example, at least twice the surface roughness of the electrode (difference between the convex portion and the concave portion). If the thickness is too small, it is difficult to sufficiently cover the convex portions on the electrode surface, and a short circuit tends to occur. Specifically, it is desirable that it is 5 μm or more, more preferably 10 μm or more. On the other hand, if the ion-permeable insulating layer is too thick, the energy density of the battery tends to decrease, so it is recommended that it be 30 μm or less, more preferably 20 μm or less. It is recommended that the ion-permeable insulating layer be selected so that the thickness ratio with the active material-containing layer in the positive electrode satisfies the above-mentioned relationship while satisfying the above-mentioned preferred value.

  In addition, by using a resin that constitutes the ion-permeable insulating layer or a thermoplastic resin that melts or softens the organic fine particles at an appropriate temperature, when the temperature inside the battery rises, the pores of the insulating layer are blocked. It is also possible to provide a shutdown function that increases the internal resistance. The shutdown temperature (temperature at which the internal resistance increases) preferably occurs at 80 to 150 ° C, more preferably 100 to 130 ° C. Therefore, the temperature at which the constituent resin (including the above organic fine particles) of the ion-permeable insulating layer melts or softens is approximately equal to the shutdown temperature, and therefore the resin that has a melting or softening temperature within the above shutdown temperature range. By using organic fine particles, the shutdown function can be satisfactorily exhibited.

  The ion-permeable insulating layer using organic fine particles may be formed by applying it to the electrode surface in a dry state, but the positive electrode and / or the negative electrode is formed on the current collector surface for forming an active material containing layer. In the case of producing by a method of applying a composition (slurry or the like), the composition for forming an ion-permeable insulating layer on the surface of the active material-containing layer (the above organic fine particles) is applied on the surface of the active material-containing layer after the composition is applied and before it is completely dried. Etc.) can also be formed by coating. By doing so, it becomes possible to integrate the drying process of the active material-containing layer of the electrode and the ion-permeable porous layer, so that the battery manufacturing process can be simplified and the cost can be reduced. .

  When organic fine particles are used as the constituent material of the ion-permeable insulating layer, the organic fine particles have electrical insulating properties, are electrochemically stable, and are used when manufacturing an electrolytic solution and a separator described later. There is no particular limitation as long as the solvent used in the composition containing the organic fine particles is stable. Specifically, polyethylene (PE), ethylene-vinyl acetate copolymer (EVA) (the structural unit derived from vinyl acetate is 35 mol% or less, more preferably less than 15 mol%), or these Fine particles containing a resin such as a derivative thereof are suitable, and these may be used alone or in combination of two or more. These organic fine particles may contain a known additive (for example, an antioxidant) in addition to the resin.

  As the size of the organic fine particles, it is sufficient that the particle size is smaller than the thickness of the ion-permeable insulating layer, but it is preferable to have an average particle size of 4/3 to 1/100 of the thickness of the separator. The average particle size is preferably 0.1 to 20 μm. If the particle size of the organic fine particles is too small, the gap between the fine particles becomes small, resulting in a long ion conduction path, which may deteriorate the battery characteristics. In addition, if the particle size of the organic fine particles is too large, the gap may become large and a problem such as a short circuit due to dendrite may occur. The average particle size of the organic fine particles herein is a number average particle size measured by dispersing the fine particles in water using a laser scattering particle size distribution size (“LA-920” manufactured by HORIBA).

  In the case where the organic fine particles have self-adhesive properties and the organic fine particles can adhere to each other in the ion-permeable insulating layer to form a layer, the insulating layer may be composed of only organic fine particles, When the organic fine particles do not have self-adhesive properties, it is preferable to form the insulating layer using a binder resin for binding the organic fine particles. Examples of the organic fine particles having self-adhesive properties include PE, EVA (the structural unit derived from vinyl acetate is less than 15 mol%), or derivatives thereof. These may be used alone or in combination of two or more. May be used simultaneously.

  The binder resin used when the organic fine particles do not have self-adhesive properties, or when the self-adhesive properties are insufficient and cannot be bonded well, and the organic fine particles and other fine particles described later can be bonded well, and electrochemical If it is stable with respect to the solvent (dispersion medium) used for the electrolyte solution used for a battery, and the composition for ion permeable insulating layer formation, it is not specifically limited. For example, polyolefin fine particles are suitable as the organic fine particles, and therefore, a resin having a polyethylene structure (methylene chain) in the molecule is suitable from the viewpoint of improving adhesiveness. Specifically, an ethylene-vinyl acetate copolymer (the structural unit derived from vinyl acetate is 15 mol% or more, more preferably 35 mol% or less), an ethylene-acrylate copolymer (ethylene-methyl acrylate copolymer, Ethylene-ethyl acrylate copolymer, etc.). Fluorine rubber can also be used. These binder resins can be used alone or in combination of two or more.

  In addition, the ion-permeable insulating layer may contain fine particles other than the organic fine particles. Such other fine particles are heat resistant, non-electrically conductive and electrochemically stable, and further to the solvent (dispersion medium) used in the electrolyte solution and the ion-permeable insulating layer forming composition. It is not particularly limited as long as it is stable. For example, non-electrically conductive inorganic fine particles (inorganic powder), high heat-resistant polymer fine particles, and the like can be mentioned. By including such fine particles in the ion-permeable insulating layer, the shape of the insulating layer is maintained even at high temperatures. Therefore, in a battery using such an insulating layer, an internal short circuit when the internal temperature rises is prevented. More highly prevented.

Examples of non-electrically conductive (electrically insulating) inorganic fine particles include oxide fine particles such as iron oxide, SiO ₂ , Al ₂ O ₃ , TiO ₂ , and BaTiO ₂ ; nitride fine particles such as aluminum nitride and silicon nitride; Insoluble ion crystal fine particles such as calcium fluoride, barium fluoride and barium sulfate; Covalent crystal fine particles such as silicon and diamond; Clay fine particles such as montmorillonite; These may be subjected to element substitution, surface treatment, or solid solution as necessary. Further, the surface of conductive fine particles such as metal fine particles; oxide fine particles such as SnO ₂ and tin-indium oxide (ITO); carbon fine particles such as carbon black and graphite; It is a fine particle that has an electrical insulating property by surface treatment with the above-mentioned materials constituting the non-electrically conductive inorganic fine particles, or materials constituting the high-heat-resistant polymer fine particles described later). Also good.

  High heat-resistant polymer fine particles include crosslinked polymethyl methacrylate, crosslinked polystyrene, crosslinked polydivinylbenzene, crosslinked styrene-divinylbenzene copolymer, polyimide, melamine resin, phenol resin, benzoguanamine-formaldehyde condensation. Examples thereof include fine particles. The polymer constituting these polymer fine particles is a mixture, modified body, derivative or copolymer of the above exemplified materials (random copolymer, alternating copolymer, block copolymer, graft copolymer). , A crosslinked body (in the case of thermoplastic polyimide) may be used.

  As the other fine particles, the fine particles exemplified above may be used alone or in combination of two or more.

  The size of the other fine particles is, for example, 0.01 μm or more, more preferably 0.1 μm or more, and 15 μm or less, more preferably 1 μm, in the number average particle diameter determined by the same measurement method as that of the organic fine particles. The following is desirable. If the other fine particles are too small, the pore diameter of the ion-permeable insulating layer may be too small and the ion permeability may deteriorate, and if too large, the pore diameter of the ion-permeable insulating layer may be too large, It becomes difficult to increase the filling amount of the fine particles, and the effect of filling the fine particles may not be sufficiently obtained.

  When the organic fine particles and other fine particles are contained in the ion-permeable insulating layer, the organic fine particles are preferably 30% by volume or more, more preferably 60% by volume or more in the total fine particles ( (Since the fine particles contained in the ion-permeable insulating layer may be all of the organic fine particles, the upper limit is 100% by volume). If the volume ratio of the organic fine particles is too small, the function of closing the vacancies in the ion-permeable insulating layer is lowered, and the effect of increasing the internal resistance of the battery during shutdown may be reduced.

  Further, when the above binder resin is used in the ion permeable insulating layer, the binder resin is 0.1% by mass or more, more preferably 1% by mass or more in all the materials constituting the ion permeable insulating layer. Therefore, it is desirable that the content be 10% by mass or less, more preferably 5% by mass or less. By setting the binder resin content to be equal to or higher than the above lower limit value, the binding effect of the fine particles constituting the ion permeable insulating layer is increased. It is possible to prevent a problem that the battery characteristics are deteriorated by blocking.

  When the organic fine particles described above are used as the constituent material of the ion permeable insulating layer, the insulating layer forming composition (slurry etc.) includes the insulating layer such as the organic fine particles, binder resin, and other fine particles. The constituent components are dissolved or dispersed in a solvent or dispersion medium. As such a solvent or dispersion medium, for example, when a binder resin is used, a solvent that can uniformly dissolve the binder resin is preferable. Specifically, organic solvents such as aromatic hydrocarbons such as toluene; furans such as tetrahydrofuran; ketones such as methyl ethyl ketone and methyl isobutyl ketone; are preferable. In these solvents, polyhydric alcohols (1,3-propanediol, 1,4-butanediol, etc.), glycol esters (ethyl glycol acetate, methyl glycol acetate, propylene glycol monomethyl) are used for the purpose of controlling interfacial tension. Acetate etc.) may be added as appropriate. In the case where the binder resin is used as an emulsion, water may be used as a solvent. In this case, alcohol (methanol, ethanol, isopropanol, etc.) can be appropriately added to control the interfacial tension.

  Examples of the method for applying the ion-permeable insulating layer forming composition to the surface of the active material-containing layer of the electrode or the surface of the base material for forming the independent film are exemplified in the method for applying the composition for forming the active material-containing layer. Various methods using various coaters can be employed. Among these, a coating method using a die coater, a curtain coater, or a spray coater is preferable. Moreover, as a drying method and conditions after application | coating of the said composition, the method and conditions of drying at about 70-120 degreeC using a hot air dryer are employable, for example.

  In producing the nonaqueous electrolyte battery of the present invention, a positive electrode with an ion-permeable insulating layer formed on the surface and an unformed negative electrode, a negative electrode with an ion-permeable insulating layer formed on the surface and an unformed positive electrode, or an ion permeable material. The positive electrode and the negative electrode on which the conductive insulating layer is formed on the surface, or the positive electrode and the negative electrode on which the ion-permeable insulating layer is not formed on the surface through the ion-permeable insulating layer which is the above independent film ( The electrode body is in the form of a laminated electrode body) or a wound body (wound electrode body). In addition to the combination of the positive electrode, the negative electrode, and the ion-permeable insulating layer, a heat-resistant porous film is also used. A rotating electrode body may be used. As such a heat-resistant porous film, a microporous film or a nonwoven fabric made of a heat-resistant resin such as polypropylene, polyimide, aramid, and polyamideimide can be used. The porosity of these porous films is preferably 40 to 90%, and the thickness is desirably 10 to 30 μm.

  The non-aqueous electrolyte of the present invention is formed by inserting the above electrode body into a rectangular tube or cylindrical outer can made of iron, stainless steel, aluminum, or the like, injecting the electrolyte, and then sealing. It can be a battery. Moreover, it can also be set as a laminate battery by sealing after inserting said electrode body in the soft package which used the laminated film which vapor-deposited the metal as an exterior material, inject | pouring electrolyte.

Examples of the electrolyte include dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propionate, ethylene carbonate, propylene carbonate, butylene carbonate, γ-butyrolactone, ethylene glycol sulfite, 1,2-dimethoxyethane, 1,3-dioxolane. , tetrahydrofuran, 2-methyl - tetrahydrofuran, one composed of only an organic solvent such as diethyl ether or a mixture of two or more solvents, for _{example, LiClO 4, LiPF 6, LiBF} 4, LiAsF 6, LiSbF 6, LiCF 3 SO _{3, LiCF 3 CO 2, Li} 2 C 2 F 4 (SO 3) 2, LiN (CF 3 SO 2) 2, LiC (CF 3 SO 2) 3, LiC n F 2n + 1 SO 3 (n ≧ 2) LiN (RfOSO _{2) 2} [wherein Rf is a fluoroalkyl group] electrolyte solution prepared by dissolving at least one selected from lithium salts such as are used. The concentration of the lithium salt in the electrolytic solution is preferably 0.5 to 1.5 mol / l, and more preferably 0.9 to 1.25 mol / l.

  Also, instead of the above organic solvents, melting at room temperature such as ethyl-methylimidazolium trifluoromethylsulfonium imide, heptyl-trimethylammonium trifluoromethylsulfonium imide, pyridinium trifluoromethylsulfonium imide, guanidinium trifluoromethylsulfonium imide A salt can also be used.

  Further, the above electrolyte solution is crosslinked with polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polyacrylonitrile, polyethylene oxide, polypropylene oxide, ethylene oxide-propylene oxide copolymer, ethylene oxide chain in the main chain or side chain. An electrolyte gelled using a known host polymer capable of forming a gel electrolyte such as a polymer can also be used.

  The nonaqueous electrolyte battery of the present invention thus obtained is excellent in quick charge characteristics and safety, and can also have high output density and high energy density. It can be suitably used as a power source for electronic devices (such as mobile phones and notebook personal computers), electric vehicles, electric scooters, electric tools and the like.

  Hereinafter, the present invention will be described in detail based on examples. However, the following examples are not intended to limit the present invention, and all modifications made without departing from the spirit of the preceding and following descriptions are included in the technical scope of the present invention.

Example 1
<Preparation of positive electrode>
LiCoO ₂ which is a positive electrode active material (average particle size is 2 μm): 80 parts by mass, acetylene black which is a conductive auxiliary agent: 10 parts by mass, and PVDF which is a binder: 10 parts by mass using NMP as a dispersion medium Was mixed to prepare a positive electrode mixture-containing paste. This paste was intermittently applied using a die coater on both surfaces of an aluminum foil having a thickness of 15 μm and a width of 900 mm as a current collector so that the coating length was 1270 mm on the front surface and 1200 mm on the back surface. The positive electrode was prepared by adjusting the thickness of the positive electrode mixture layer (active material-containing layer) so that the total thickness was 35 μm. The positive electrode was slit to a width of 43 mm and then heat-treated at 140 ° C. for 8 hours with a hot air dryer.

<Production of negative electrode>
Graphite (average particle size: 2.5 μm) as negative electrode active material: 90 parts by mass and PVDF as binder: 10 parts by mass are mixed with NMP as a dispersion medium to contain a negative electrode mixture A paste was prepared. This paste was intermittently applied on both sides of a current collector made of copper foil with a thickness of 10 μm and a width of 900 mm with a die coater so that the coating length was 1280 mm on the front surface and 1205 mm on the back surface. The negative electrode was prepared by adjusting the thickness of the negative electrode mixture layer (active material-containing layer) so that the total thickness was 29 μm. The negative electrode was slit into a width of 44 mm, and then heat-treated at 110 ° C. for 3 hours with a hot air dryer.

<Preparation of ion-permeable insulating layer>
As a binder resin, EVA emulsion (vinyl acetate-derived structural unit is 20 mol%, manufactured by Sumika Chemtex Co., Ltd.) 100 g, PE fine particle aqueous dispersion [Mitsui Chemicals “Chemical W-700” (trade name)] 1000 g, 400 g of alumina (Al ₂ O ₃ ) fine particles [“Sumicorundum AA04” (trade name) manufactured by Sumitomo Chemical Co., Ltd.] were placed in a container and stirred at room temperature to form a slurry. This slurry was applied to the negative electrode surface using a curtain coater, moisture was removed, and an ion-permeable insulating layer having a thickness of 10 μm was formed.

<Production of battery>
A lead part was attached to the negative electrode in which the positive electrode and the ion-permeable insulating layer were integrated, and the positive electrode and the negative electrode were overlapped and wound to produce a wound electrode body. This wound electrode body is loaded in a laminate film outer package (manufactured by Showa Aluminum Co., Ltd.), and 1.2 mol of LiPF ₆ is added to a solvent in which an electrolytic solution (ethylene carbonate and ethyl methyl carbonate is mixed at a volume ratio of 1: 2). A solution dissolved at a concentration of / l was injected and vacuum sealed to produce a laminated nonaqueous electrolyte battery.

Example 2
A laminated nonaqueous electrolyte battery was produced in the same manner as in Example 1 except that the ion-permeable insulating layer was produced as follows. EVA (33 mol% vinyl acetate-derived structural unit, manufactured by Exxon Mobil) 0.9 g, Exxon-Mobil Chemical Co. , Houston, TX aromatic modified aliphatic hydrocarbon resin “Escorez® 2596” 0.36 g, and polysulfone (PSU) (Scientific Polymer Products Inc., manufactured by Ontario, NY, Mw: 80,000) 4 .14 g was placed in a container and 40 g of THF was added and dissolved. To this solution was added 1.00 g of fumed silica (“S5130” from Sigma-Aldrich Co.). The mixture was stirred overnight to give a slurry. To this slurry, 7.00 g of lithium bromide (LiBr) was added and dissolved. The obtained slurry was applied to the negative electrode surface using a doctor blade so as to have a dry thickness of 15 μm, THF was evaporated and dried at room temperature, and immediately immersed in water for 1 hour to remove LiBr and ion-permeable insulation. A layer was made.

Example 3
The positive electrode active material was changed to LiCoO ₂ having an average particle diameter of 1 μm, the coating length of the positive electrode mixture-containing paste on the current collector surface was set to 1600 mm on the front surface and 1530 mm on the back surface, and the total thickness after the calendar treatment was adjusted to 25 μm. A positive electrode was produced in the same manner as Example 1 except for the above. Further, a negative electrode was produced in the same manner as in Example 1 except that the coating length of the negative electrode mixture-containing paste on the current collector surface was 1620 mm on the front surface and 1550 mm on the back surface. An ion-permeable insulating layer was formed on the negative electrode surface in the same manner as in Example 1, and a laminated nonaqueous electrolyte battery was produced in the same manner as in Example 1.

Example 4
A positive electrode and a negative electrode were produced in the same manner as in Example 3, and the same as in Example 3 except that a PE microporous membrane (“E16MMS” manufactured by Tonen Chemical Nasu Co., Ltd., thickness 16 μm) was used as the ion-permeable insulating layer. Thus, a laminated nonaqueous electrolyte battery was produced.

Comparative Example 1
A laminated nonaqueous electrolyte battery was produced in the same manner as in Example 1 except that the thickness of the ion-permeable insulating layer was 4 μm.

Comparative Example 2
The positive electrode active material was changed to LiCoO ₂ having an average particle size of 10 μm, the coating length of the positive electrode mixture-containing paste on the current collector surface was set to 280 mm on the front surface and 210 mm on the back surface, and the total thickness after calendar treatment was adjusted to 155 μm. A positive electrode was produced in the same manner as Example 1 except for the above. Also, the negative electrode active material was changed to graphite having an average particle diameter of 11 μm, the coating length of the negative electrode mixture-containing paste on the current collector surface was adjusted to 290 mm on the front surface and 230 mm on the back surface, and the total thickness after calendar treatment was adjusted to 142 μm. A negative electrode was produced in the same manner as in Example 1 except that. Using this positive electrode and negative electrode, a laminate non-aqueous solution was used in the same manner as in Example 1 except that a PE microporous membrane (“EMM-20” manufactured by Tonen Chemical Nasu) having a thickness of 20 μm was used as the ion-permeable insulating layer. An electrolyte battery was produced.

Comparative Example 3
The positive electrode active material was changed to LiCoO ₂ having an average particle size of 10 μm, the coating length of the positive electrode mixture-containing paste on the current collector surface was 280 mm on the front surface and 210 mm on the back surface, and the total thickness after calendar treatment was adjusted to 295 μm. A positive electrode was produced in the same manner as Example 1 except for the above. Also, the negative electrode active material was changed to graphite having an average particle diameter of 11 μm, the coating length of the negative electrode mixture-containing paste on the current collector surface was adjusted to 290 mm on the front surface and 230 mm on the back surface, and the total thickness after calendar treatment was adjusted to 142 μm. A negative electrode was produced in the same manner as in Example 1 except that. An ion-permeable insulating layer was formed on the negative electrode surface in the same manner as in Example 1, and a laminated nonaqueous electrolyte battery was produced in the same manner as in Example 1.

  The non-aqueous electrolyte batteries of Examples 1 to 4 and Comparative Examples 1 to 3 were subjected to the following electrochemical evaluation, and those having good evaluation results were subjected to the following overcharge test. The results are shown in Table 1. Table 1 also shows the thickness of the active material-containing layer in the positive electrode, the capacity density theoretically calculated for the active material-containing layer, the thickness of the ion-permeable insulating layer, and the theoretically calculated battery energy density. .

<Electrochemical evaluation>
About the battery of Examples 1-4 and Comparative Examples 1-3, it charged on the following charging conditions (B). That is, each battery was continuously charged at a constant voltage of 4.2 V until it reached 4.2 V at a constant current of 0.2 C. The total time from the start of constant current charging to the end of constant voltage charging was 7 hours. About each battery after charge, discharge from 4.2V to 3.0V was performed at 0.2C, and each capacity | capacitance was measured.

  Next, each battery was charged under the following charging conditions (A). That is, each battery was continuously charged at a constant voltage of 4.2 V until it reached 4.2 V at a constant current of 6 C. The total time from the start of constant current charge to the end of constant voltage charge was 10 minutes, and the constant current charge time was 8 minutes or more in any battery. About each battery after charge, discharge from 4.2V to 3.0V was performed at 0.2C, and each capacity | capacitance was measured.

  And about each battery, the ratio (namely, rapid charge capacity ratio,%) of the capacity | capacitance in charge condition (A) with respect to the capacity | capacitance in charge condition (B) was calculated | required, and the rapid charge characteristic was evaluated. The larger the quick charge capacity ratio, the better the quick charge characteristics.

<Overcharge test>
In the above electrochemical evaluation, the battery having a rapid charge capacity ratio of 80% or more was subjected to constant current charging for 1 hour under the conditions of 6C and 15V, and the safety of the battery was evaluated based on the presence or absence of ignition.

  In Table 1, “*” in the column of the quick charge capacity ratio of Comparative Example 2 means that a short circuit occurred during charging under the charging condition (A).

  As shown in Table 1, the batteries of Examples 1 to 4 are excellent in quick charge characteristics and have good safety. On the other hand, the battery of Comparative Example 1 has excellent quick charge characteristics but is inferior in safety. Further, the batteries of Comparative Example 2 and Comparative Example 3 are inferior in quick charge characteristics.

Claims (7)

A positive electrode having an active material-containing layer containing an active material capable of occluding and releasing lithium ions on one or both sides of a current collector, a negative electrode containing an active material capable of occluding and releasing lithium ions, and the positive electrode and the negative electrode A non-aqueous electrolyte battery having an ion-permeable insulating layer interposed between
The capacity per unit volume of the active material-containing layer in the positive electrode is 250 mAh / cm ³ or more,
The total charging time is 10 minutes, and the charging capacity when charging under the condition that the charging time at a current value of 5C or more is 8 minutes or more is constant current charging to 4.2V at 0.2C. . 80% or more of the charging capacity when charging at a constant voltage of 2 V and the total charging time is 7 hours,
A non-aqueous electrolyte battery that does not ignite even when charged for 1 hour under conditions of 6C and 15V.   The nonaqueous electrolyte battery according to claim 1, wherein the active material-containing layer in the positive electrode has a thickness of 30 μm or less. A positive electrode having an active material-containing layer containing an active material capable of occluding and releasing lithium ions on one or both sides of a current collector, a negative electrode containing an active material capable of occluding and releasing lithium ions, and the positive electrode and the negative electrode A non-aqueous electrolyte battery having an ion-permeable insulating layer interposed between
A nonaqueous electrolyte battery, wherein the active material-containing layer in the positive electrode has a thickness of 30 μm or less, and the ion-permeable insulating layer has a thickness equal to or greater than the thickness of the active material-containing layer in the positive electrode. The nonaqueous electrolyte battery according to claim 3, wherein the capacity per unit volume of the active material-containing layer in the positive electrode is 250 mAh / cm ³ or more.   The nonaqueous electrolyte battery according to claim 1, wherein the ion-permeable insulating layer has a thickness of 5 to 30 μm.   The non-aqueous electrolyte battery according to claim 1, wherein the ion-permeable insulating layer is integrated with a positive electrode and / or a negative electrode. The ion permeable insulating layer is formed by applying an ion permeable insulating layer forming composition containing a constituent material of the ion permeable insulating layer. Non-aqueous electrolyte battery.