JP2008059765A - Non-aqueous secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-aqueous secondary battery having a high capacity and a long life.
A negative electrode having a negative electrode mixture layer containing a specific high-capacity material or carbon particles on both sides of a support, and a positive electrode having a positive electrode mixture layer containing a lithium composite oxide on both sides of the support. A negative electrode comprising a through hole penetrating from one surface to the other surface, and the negative electrode support and the positive electrode support are made of rolled copper, electroless copper, or a copper alloy. Or a positive electrode support made of aluminum or an aluminum alloy has a thickness of 20 to 40 μm, a porosity of 30 to 70%, and a tensile strength of 5 to 30 N / 15 mm width. The above battery solves the above problem.
[Selection] Figure 2

Description

  The present invention relates to a non-aqueous secondary battery that can achieve high capacity and long life.

  In recent years, the demand for mobile terminal devices such as mobile phones, notebook PCs, and PDAs has been rapidly increasing, and non-aqueous secondary batteries (lithium secondary batteries) used as a power source in accordance with the reduction in size and weight and increase in functionality. ) High energy density and long life. However, the capacity of non-aqueous secondary batteries currently in practical use has almost reached the theoretical value of carbon, which is a negative electrode active material. Under such circumstances, development of a high-capacity negative electrode material is expected for further increase in energy density.

  On the other hand, a lithium secondary battery using a negative electrode using a metal or semiconductor such as Al, Si, or Sn that can be alloyed with Li during charging as an active material has also been reported (Non-Patent Document 1). A negative electrode material (negative electrode active material) using the above-described metal or semiconductor oxide or nitride has also been proposed. Each active material is very promising as a negative electrode material because both its weight capacity density and volume capacity density are very high compared to carbon.

  However, in batteries using negative electrodes made of the above metals and semiconductors, as well as oxides and nitrides of these, when charging and discharging are repeated, the negative electrode material is pulverized due to expansion and contraction associated with the charging and discharging. As a result, the contact between the negative electrode material particles in the negative electrode is impaired, the resistance increases, and the discharge capacity decreases early. This is because the negative electrode material described above has a higher capacity than the carbon material, and therefore, more Li ions are occluded, so that the volume change due to charge / discharge is increased and pulverization occurs.

  In order to suppress the occurrence of problems due to the above volume change and achieve a long battery life, for example, a thin film made of the above metal or semiconductor, and further a negative electrode material using these oxides and nitrides is plated. A method of forming a metal support (current collector) on the surface of a metal support (current collector) by chemical vapor deposition, chemical vapor deposition (CVD), or sputtering (Patent Document 1), or a method of using these negative electrode materials mixed with a carbon material having a small volume change Etc. have been proposed.

  However, for example, in the method of forming a thin film made of the above negative electrode material on the surface of the metal support by a plating method, chemical vapor deposition method, or sputtering method, there is substantially no void in the formed thin film made of the negative electrode material. Since it does not exist, pulverization due to expansion and contraction of the negative electrode material accompanying charging / discharging of the battery cannot be sufficiently suppressed, and the manufacturing cost becomes expensive.

  In order to suppress the expansion and contraction of the negative electrode material accompanying charging / discharging of the battery, it is effective to make the negative electrode material itself fine particles. However, in the case of using a fine particle negative electrode material, for example, a negative electrode mixture layer containing the negative electrode material is formed on a metal support to constitute the negative electrode. When the negative electrode material is a fine particle, the negative electrode mixture layer A large amount of binder and conductive auxiliary agent are required in the battery, the packing density of the negative electrode mixture layer is lowered, making it difficult to increase the capacity of the battery, and further improving the charge / discharge cycle life cannot be expected.

  Further, in a negative electrode having a negative electrode mixture layer on a metal support or a positive electrode having a positive electrode mixture layer containing a positive electrode active material on a metal support, for example, an electrode mixture layer (negative electrode mixture) is formed on both surfaces of the metal support. If the electrode mixture layers are not equal in amount, for example, the following problems occur.

  During electrode production, press treatment is usually performed to adjust the thickness and density of the electrode mixture layer, but when the electrode mixture layers on both sides of the metal support are not equal to each other, Since there is a difference in elongation between one side and the other side, peeling and dropping of the electrode mixture layer are likely to occur.

  In addition, if the electrode mixture layers on both sides of the metal support are not equal to each other, a difference occurs between the one side of the electrode and the other side in the absorption and release of Li ions during charge and discharge, and the electrode mixture is more Li metal is likely to be deposited on the side with fewer layers (the side with less active material).

  In a battery configured using a positive electrode having a positive electrode mixture layer on both sides of a metal support and a negative electrode having a negative electrode mixture layer on both sides of the metal support, Li ions between the opposite positive electrode and negative electrode Occlusion and release are performed in a region partitioned by the positive electrode support and the negative electrode support, that is, the positive electrode mixture layer on the side facing the negative electrode in the positive electrode mixture layer of the positive electrode, and the negative electrode of the negative electrode This is mainly performed between the mixture layer and the negative electrode mixture layer on the side facing the positive electrode. Therefore, even if the thickness of the positive electrode or the negative electrode is controlled to adjust the amount of the electrode mixture layer as the whole positive electrode or the whole negative electrode, the amount of each electrode mixture layer is not equal. On the surface of the electrode having a smaller amount of the electrode mixture layer, the amount of Li ions that can be occluded decreases, so that the portion that cannot be occluded is deposited as Li metal.

  As described above, when a battery in which Li metal is likely to precipitate is repeatedly charged and discharged over a long period of time, the deposited Li metal may cause a short circuit or ignition, and even if it does not lead to ignition, its life is shortened. End up.

  For this reason, in non-aqueous secondary batteries configured using electrodes having electrode mixture layers on both sides of a metal support, in order to increase the reliability and extend the life, Strict management is required so that the electrode mixture layers formed on both surfaces of the metal support are as equal as possible.

JP 2003-217574 A Solid State Ionics, 1998, 113-115, p57

  This invention is made | formed in view of said situation, The objective is to provide a high capacity | capacitance and a long life non-aqueous secondary battery.

  The non-aqueous secondary battery of the present invention that has achieved the above object is capable of inserting and extracting Li (lithium) ions, and has the following configuration (1) or (2). It is a feature.

(1) An anode mixture layer containing at least one active material selected from the group consisting of an element capable of forming an alloy with Li and its compound, and carbon particles capable of occluding and releasing Li ions is provided on both sides of the support. And a positive electrode having a positive electrode mixture layer containing a lithium composite oxide on both sides of the support, and the negative electrode support and the positive electrode support are arranged from one side to the other side. The negative electrode support is made of rolled copper, electroless copper or a copper alloy, has a thickness of 20 to 40 μm, an open area ratio of 30 to 70%, and a tensile strength. The strength is 5 to 30 N / 15 mm.

(2) An anode mixture layer containing at least one active material selected from the group consisting of an element capable of forming an alloy with Li and its compound, and carbon particles capable of occluding and releasing Li ions is provided on both sides of the support. And a positive electrode having a positive electrode mixture layer containing a lithium composite oxide on both sides of the support, and the negative electrode support and the positive electrode support are arranged from one side to the other side. The positive electrode support is made of aluminum or an aluminum alloy, has a thickness of 20 to 40 μm, an open area ratio of 30 to 70%, and a tensile strength of 5 to 30 N. / 15 mm.

  In the non-aqueous secondary battery of the present invention, both the positive and negative electrode supports have through-holes (hereinafter abbreviated as “through-holes”) penetrating from one surface to the other surface. The following effects can be exhibited.

  Since a part of the mixture layer is filled in the through holes of the support for the positive electrode and the negative electrode, the positive electrode mixture layer on both sides of the positive electrode and the negative electrode mixture layer on both sides of the negative electrode are integrated. Therefore, it is easy to apply pressure at the time of pressing when manufacturing the positive electrode and the negative electrode, and it becomes easy to increase the packing density of the positive electrode mixture layer and the negative electrode mixture layer, so that a high capacity battery can be configured.

  In addition, since the positive electrode mixture layer on both sides of the positive electrode and the negative electrode mixture layer on both sides of the negative electrode are integrated with each other through the through holes of the support, the expansion and contraction of the active material accompanying the charging / discharging of the battery is further reduced. It can be mitigated, and the active material can be prevented from being pulverized, thereby extending the battery life.

  Furthermore, even if there is a difference between the amount of the mixture layer on one side of the electrode and the amount of the mixture layer on the other side, the positive electrode mixture layer on both sides of the positive electrode and the negative electrode The negative electrode mixture layers on both sides act as a single body without being blocked by the support, and the nonaqueous electrolyte can be uniformly distributed through the through holes in the entire positive electrode and the entire negative electrode. Therefore, since the uniformity of the Li ion storage / release reaction can be improved, Li metal deposition is unlikely to occur even after repeated charge and discharge over a long period of time, thus improving the reliability of the battery and extending its life. it can. In addition, in any of the positive electrode and the negative electrode, it is not necessary to strictly manage such that the mixture layers on both sides of the support are equal to each other at the time of production. Can be easily.

  In the nonaqueous secondary battery of the present invention, it is preferable that both the above aspects (1) and (2) are satisfied.

  According to the present invention, a non-aqueous secondary battery having a high capacity and a long life can be provided.

  The negative electrode according to the non-aqueous secondary battery of the present invention is such that a negative electrode mixture layer containing an active material is formed on both surfaces of a support serving as a current collector, and the support has through holes. Have.

  Examples of the material for the negative electrode support include rolled copper, electroless copper, and a copper alloy. In view of the strength when through holes are formed, electroless copper with less strain is preferable.

  The thickness of the negative electrode support is preferably 40 μm or less, more preferably 30 μm or less, from the viewpoint of increasing the filling amount of the negative electrode active material. On the other hand, if the support of the negative electrode is too thin, the negative electrode may be cracked or cut when the through hole is formed or the electrode is wound (described later). Therefore, the thickness of the negative electrode support is preferably 20 μm or more.

  The porosity of the negative electrode support is increased by increasing the packing density of the negative electrode mixture layer to increase the capacity of the battery, and the negative electrode mixture layers on both sides of the support are integrated by forming through holes. From the viewpoint of more effectively exhibiting the action of prolonging the lifetime, it is preferably 30% or more, and more preferably 40% or more. Further, if the opening ratio of the negative electrode support is too large, the negative electrode may be cracked or cut when the through hole is formed or the electrode is wound. Therefore, the porosity of the negative electrode support is preferably 70% or less, and more preferably 60% or less. The open area ratio of the support (negative electrode support and positive electrode support) in this specification is the percentage of the total area of the through holes to the area of the support in plan view. .

  In addition, the negative electrode support has a tensile strength measured using a 15 mm wide sample from the viewpoint of more effectively preventing the occurrence of cracking and cutting of the negative electrode at the time of forming the through-hole or winding the electrode. It is preferably 5N or more (that is, 5N / 15 mm width or more), and more preferably 10N or more (that is, 10N / 15 mm width or more). The tensile strength of the negative electrode support can be adjusted by selecting the material, thickness and porosity of the support within the ranges described above, and the upper limit of the tensile strength that can be secured by these selections is For example, the width is 30 N / 15 mm.

  There is no particular limitation on the method of forming the through hole in the negative electrode support, and it may be formed by punching a foil as a material of the support, as in a known punching metal, or as in a known expanded metal. The foil as a body material may be formed by being cut out while being cut, or may be formed by other methods.

  The negative electrode mixture layer according to the negative electrode contains at least one negative electrode active material selected from the group consisting of elements capable of forming an alloy with Li and compounds thereof, and carbon particles capable of occluding and releasing Li ions.

  Among the negative electrode active materials, elements capable of forming an alloy with Li and their compounds are so-called high-capacity materials. By using these active materials to form a negative electrode, it is possible to increase the capacity of the battery. it can. These high capacity materials may be in a crystalline, low crystalline or amorphous state.

Examples of elements that can form an alloy with Li include Si, Sn, Ge, Ag, In, Pb, and Al. Among these, Si, Sn, and Al are preferable from the viewpoint of material cost and handleability. The high-capacity material may be a simple substance of these elements or an alloy (solid solution or intermetallic compound) containing these elements. Moreover, the compound of the said element, such as an oxide and nitride, may be sufficient. Examples of the oxide of the element include SiO, SnO, SnO ₂ , and Sn—B—P—O composite oxide. Furthermore, examples of the nitride of the element include SiAlON, Si ₃ N ₄ , and AlN. In the case of a high-capacity material containing Si or Ge (Si or Ge alone, or an oxide or nitride thereof), for example, it becomes an n-type or p-type semiconductor by doping with boron or phosphorus. Alternatively, a material whose electric resistance is greatly reduced may be used.

The above high-capacity material has an average particle diameter of 1 μm or more, more preferably 2 μm or more, and preferably 10 μm or less from the viewpoint of further suppressing expansion and contraction of the negative electrode. In addition, the average particle diameter of the high-capacity material referred to in this specification is a volume-based integrated fraction obtained by a laser diffraction measurement method using “HRA (Model: 9320-X100)” manufactured by Microtrack. The 50% diameter value (d ₅₀ ).

  In addition, carbon particles capable of occluding and releasing Li ions can be used for the negative electrode active material. The carbon particles that can be used as the negative electrode active material include amorphous carbon and graphite as materials that are excellent in reversibility and do not cause Li metal to precipitate on the active material surface by a charge / discharge cycle. Examples of graphite include various graphite materials such as natural graphite, artificial graphite, graphite with impurities reduced by acid treatment, mesocarbon microbeads (MCMB), and graphitized carbon fiber. Graphite has high crystallinity, a change in potential due to insertion and extraction of Li ions is small, and a capacity that can be used as a battery is increased.

  Furthermore, you may use together said high capacity | capacitance material and said carbon particle for a negative electrode active material. By using the high-capacity material and carbon particles in combination, the expansion and contraction of the active material during charging and discharging can be further suppressed while increasing the capacity of the negative electrode.

  When using the above high-capacity material and carbon particles in combination with the negative electrode active material, to effectively exhibit the expansion and contraction suppressing action of the negative electrode active material during charge and discharge by using carbon particles, and to extend the battery life For example, when the total of the high-capacity material and the carbon particles is 100% by mass, the ratio of the carbon particles is preferably 30% by mass or more, and more preferably 40% by mass or more. Further, in order to more effectively exhibit the effect of improving the negative electrode capacity due to the use of the high-capacity material, for example, when the total of the high-capacity material and the carbon particles is 100% by mass, the ratio of the carbon particles is set to 70% by mass. % Or less, and more preferably 60% by mass or less.

  For the negative electrode mixture layer, a binder is used together with the negative electrode active material. The binder for the negative electrode mixture layer is not particularly limited. For example, fluorine-based materials [polyvinylidene fluoride (PVDF), polytetrafluoroethylene, fluororubber, etc.], styrene butyl rubber, polyethylene, polypropylene, acrylic resin Among them, a fluorine-based material is preferable.

  Moreover, a conductive support agent can also be contained in the negative mix layer as needed. As the conductive additive, those known in the battery field can be used, and specific examples include acetylene black, ketjen black, natural graphite, artificial graphite and the like.

  In manufacturing the negative electrode, a negative electrode active material, a binder, a conductive additive and the like are dispersed in a solvent to prepare a negative electrode mixture-containing composition (paste, slurry, etc.) (the binder is dissolved in the solvent. Alternatively, it is possible to employ a method in which the composition is applied to a support, dried and subjected to a press treatment. Examples of the solvent used in the negative electrode mixture-containing composition include N-methyl-2-pyrrolidone (NMP) and N, N-dimethylformamide (DMF). In addition, the manufacturing method of a negative electrode is not necessarily limited to said method, You may employ | adopt another manufacturing method.

The drying condition after applying the negative electrode mixture-containing composition to the support is preferably, for example, 60 to 120 ° C. for 2 to 4 hours. Moreover, it is preferable that the conditions in the case of the press process after drying shall be 1-10 ton / cm < ² >, for example.

  When only the above carbon particles are used for the negative electrode active material, the thickness of the negative electrode mixture layer (thickness per one side) is preferably 40 to 100 μm, for example. On the other hand, when the above-mentioned high-capacity material is used for the negative electrode active material (when only a high-capacity material is used or when a high-capacity material and carbon particles are used in combination), the negative electrode active material itself has a large capacity. The thickness of the agent layer (thickness per one side) is preferably 20 to 80 μm, for example.

  Note that the thinner the negative electrode mixture layer, the smaller the amount of the negative electrode mixture layer on both sides of the support, the above problem (especially the amount of the negative electrode mixture layer is reduced by repeated charge and discharge). The problem that a Li metal is deposited on the side to cause a short circuit is likely to occur. However, according to the present invention, even when the negative electrode mixture layer is a very thin negative electrode as in the case where the above-described high-capacity material is used as the negative electrode active material, the above problem can be satisfactorily avoided. Therefore, when the above-described high-capacity material is used for the negative electrode active material, the effect of the present invention is more remarkably exhibited.

  The content of the negative electrode active material in the negative electrode mixture layer is preferably 80% by mass or more, more preferably 85% by mass or more, and 95% by mass or less, more preferably 90% by mass or less. Further, the binder content in the negative electrode mixture layer is 1% by mass or more, more preferably 3% by mass or more, and is preferably 15% by mass or less, more preferably 10% by mass or less. Furthermore, when the negative electrode mixture layer contains a conductive additive, the content of the conductive auxiliary in the negative electrode mixture layer is 1% by mass or more, more preferably 2% by mass or more, and 10% by mass or less. More preferably, the content is 5% by mass or less.

  The positive electrode according to the non-aqueous secondary battery of the present invention is such that a positive electrode mixture layer containing a lithium composite oxide as an active material is formed on both surfaces of a support serving as a current collector, and the above The support has a through hole.

  Examples of the material for the positive electrode support include aluminum and aluminum alloys. Aluminum or aluminum alloy used for the support is usually produced by rolling, but after rolling, it is preferable to remove the strain by annealing at around 200 ° C.

  From the viewpoint of increasing the filling amount of the positive electrode active material, the thickness of the support for the positive electrode is preferably 40 μm or less, and more preferably 30 μm or less. If the positive electrode support is too thin, the positive electrode may be cracked or cut when the through-hole is formed or the electrode is wound. Therefore, the thickness of the positive electrode support is preferably 20 μm or more.

  The porosity of the positive electrode support is increased by increasing the packing density of the positive electrode mixture layer to increase the capacity of the battery, and the positive electrode mixture layers on both sides of the support are integrated by forming through holes. From the viewpoint of more effectively exhibiting the action of prolonging the lifetime, it is preferably 30% or more, and more preferably 40% or more. In addition, if the opening ratio of the support for the positive electrode is too large, the positive electrode may be cracked or cut when the through hole is formed or the electrode is wound. Therefore, the porosity of the positive electrode support is preferably 70% or less, and more preferably 60% or less.

  In addition, the support for the positive electrode has a tensile strength measured using a 15 mm wide sample from the viewpoint of more effectively preventing the occurrence of cracking and cutting of the positive electrode during the formation of the through-hole and during the winding of the electrode. It is preferably 5N or more (that is, 5N / 15 mm width or more), and more preferably 10N or more (that is, 10N / 15 mm width or more). The tensile strength of the positive electrode support can be adjusted by selecting the material, thickness and porosity of the support within the ranges described above, and the upper limit of the tensile strength that can be secured by these selections is For example, the width is 30 N / 15 mm.

  The method for forming the through hole in the support for the positive electrode is not particularly limited, and it may be formed by punching a foil as a material for the support, as in a known punching metal, or supported as in a known expanded metal. The foil as a body material may be formed by being cut out while being cut, or may be formed by other methods.

There are no particular limitations on the lithium composite oxide that is the positive electrode active material, and various types can be used. In particular, Li _x CoO ₂ , Li _x NiO ₂ , Li _x MnO ₂ , Li _x Co _y Ni _1-y O _{2, Li x Co y M 1} -y O 2, Li x Ni 1-y M y O 2, Li x Mn y Ni z Co 1-y-z O 2, Li x Mn 2 O 4, Li x Mn 2 etc. _-y M _y O ₄ (provided that, in the above lithium composite oxide, M is at least one metal element selected Mg, Mn, Fe, Co, Ni, Cu, Zn, from the group consisting of Al and Cr And 0 ≦ x ≦ 1.1, 0 <y <1.0, and 2.0 ≦ z ≦ 2.2. These may be used alone or in combination of two types. You may use the above together.

  In the positive electrode mixture layer, a binder and a conductive additive are used together with the positive electrode active material. As the binder, the above-described various binders exemplified as those usable for the negative electrode can be used. Also, as the conductive auxiliary agent, the various conductive auxiliary agents exemplified as those usable for the negative electrode can be used.

  In producing a positive electrode, a positive electrode active material, a binder, a conductive additive, etc. are dispersed in a solvent to prepare a positive electrode mixture-containing composition (paste, slurry, etc.) (the binder is dissolved in the solvent. Alternatively, it is possible to employ a method in which the composition is applied to a support, dried and subjected to a press treatment. Examples of the solvent used for the positive electrode mixture-containing composition include NMP and DMF. In addition, the manufacturing method of a positive electrode is not necessarily limited to said method, You may employ | adopt another manufacturing method.

The drying condition after applying the positive electrode mixture-containing composition to the support is preferably, for example, 60 to 120 ° C. for 2 to 4 hours. Moreover, it is preferable that the conditions in the case of the press process after drying shall be 1-10 ton / cm < ² >, for example.

  The thickness of the positive electrode mixture layer (thickness per one side) is preferably 40 to 100 μm, for example.

  The content of the positive electrode active material in the positive electrode mixture layer is preferably 80% by mass or more, more preferably 85% by mass or more, and 95% by mass or less, more preferably 90% by mass or less. Further, the binder content in the positive electrode mixture layer is 1% by mass or more, more preferably 3% by mass or more, and is preferably 15% by mass or less, more preferably 10% by mass or less. Furthermore, the content of the conductive additive in the positive electrode mixture layer is 1% by mass or more, more preferably 2% by mass or more, and is preferably 10% by mass or less, more preferably 5% by mass or less.

  In the nonaqueous secondary battery of the present invention, there are no particular limitations on the components and structures other than the negative electrode and the positive electrode, and various components and structures that are applied in conventionally known nonaqueous secondary batteries may be adopted. it can.

  As the separator, it is preferable that the separator has sufficient strength and can hold a large amount of the electrolytic solution. From such a viewpoint, a polyethylene, polypropylene, or ethylene-propylene copolymer having a thickness of 10 to 50 μm and an aperture ratio of 30 to 70% is used. A microporous film or a nonwoven fabric containing a polymer is preferable.

  The non-aqueous secondary battery of the present invention is a laminated electrode body obtained by superposing the positive electrode and the negative electrode with the separator interposed therebetween, or a wound electrode body in which the laminated electrode body is wound. It is preferable that the body is enclosed in a battery outer body (battery can, metal laminate film outer body, etc.) together with a non-aqueous electrolyte.

  As the nonaqueous electrolytic solution (hereinafter simply referred to as “electrolytic solution”), a solution prepared by dissolving the following inorganic ion salt in the following solvent can be used.

  Examples of the solvent include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate (MEC), γ-butyrolactone, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane, acetonitrile, nitromethane, methyl formate, methyl acetate, phosphoric acid triester, trimethoxymethane, dioxolane derivative, sulfolane, 3-methyl- Aprotic organic solutions such as 2-oxazolidinone, propylene carbonate derivatives, tetrahydrofuran derivatives, diethyl ether, 1,3-propane sultone And it can be used alone or in combination.

As the inorganic ion salt, Li salt, for _{example, LiClO 4, LiBF 4, LiPF} 6, LiCF 3 SO 3, LiCF 3 CO 2, LiAsF 6, LiSbF 6, LiB 10 Cl 10, lower aliphatic carboxylic acids Li, LiAlCl ₄ , LiCl, LiBr, LiI, chloroborane Li, Li tetraphenylborate, or the like can be used alone or in combination.

Among the electrolytic solutions in which the inorganic ion salt is dissolved in the solvent, a solvent containing at least one selected from the group consisting of 1,2-dimethoxyethane, diethyl carbonate, and methyl ethyl carbonate, and ethylene carbonate or propylene carbonate In addition, an electrolytic solution in which at least one inorganic ion salt selected from the group consisting of LiClO ₄ , LiBF ₄ , LiPF ₆ , and LiCF ₃ SO ₃ is dissolved is preferable. An appropriate concentration of the inorganic ion salt in the electrolytic solution is, for example, 0.2 to 3.0 mol / dm ³ .

  Moreover, in the non-aqueous secondary battery of this invention, there is no restriction | limiting in particular also about the shape. For example, any of a coin shape, a button shape, a sheet shape, a laminated shape, a cylindrical shape, a flat shape, a square shape, a large size used for an electric vehicle, etc. may be used.

  Since the non-aqueous secondary battery of the present invention has a high capacity and a long life, conventionally known non-aqueous secondary batteries are applied, including power supplies for small and multifunctional portable devices, taking advantage of its characteristics. It can be preferably used for various applications.

  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
A through hole having a diameter of 0.3 mm was formed in electrolytic copper having a thickness of 20 μm so as to have a hole area ratio of 30%, thereby providing a negative electrode support.

  Further, a through hole having a diameter of 0.3 mm was formed in aluminum having a thickness of 20 μm so as to have a hole area ratio of 30%, thereby forming a positive electrode support. FIG. 1 shows a schematic plan view of a part of the negative electrode support and the positive electrode support. In FIG. 1, 10 is a positive or negative electrode support, and 11 is a through hole.

  About the support body of a negative electrode, and the support body of a positive electrode, the sample of 15 mm width was produced and the tension test was done at speed | rate 10 cm / min. The tensile strength of the negative electrode support was 7.5 N (7.5 N / 15 mm width), and the tensile strength of the positive electrode support was 8.5 N (8.5 N / 15 mm width).

<Production of negative electrode>
As the negative electrode active material, SiO (average particle size: 1 μm), which is an oxide of an element that can be alloyed with Li, and MCMB (average particle size: 5 μm), which is carbon particles capable of occluding and releasing Li ions, were used. SiO and MCMB were used in a mass ratio of 70:30, and acetylene black was further added and dry mixed. In this mixed powder, NMP in which PVDF was dissolved was uniformly dispersed to prepare a negative electrode mixture-containing paste. This negative electrode mixture-containing paste was applied to both surfaces of the negative electrode support, dried at 100 ° C. for 1 hour, and then pressed until the thickness became 75 μm to obtain a negative electrode sheet.

The composition of the obtained negative electrode sheet in the negative electrode mixture layer was (SiO + MCMB): acetylene black: PVDF = 93: 3: 4 (mass ratio), and the density of the negative electrode mixture layer was 1.5 g / cm ^3. Met.

<Preparation of positive electrode>
Li _1.01 CoO ₂ (positive electrode active material, specific surface area 1.7 m ² / g), which is a layered lithium cobalt oxide, and acetylene black, which is a conductive auxiliary agent, were dry mixed. In this mixture, NMP in which PVDF was dissolved was uniformly dispersed to prepare a positive electrode mixture-containing paste. This positive electrode mixture-containing paste was applied to both surfaces of the positive electrode support and dried, and then pressed until the thickness reached 180 μm to obtain a positive electrode sheet.

The composition of the obtained positive electrode sheet in the positive electrode mixture layer was Li _1.01 CoO ₂ : acetylene black: PVDF = 92: 4: 4 (mass ratio), and the density of the positive electrode mixture layer was 4.1 g. / Cm ³ .

<Battery assembly>
A Ni ribbon is attached to the outermost peripheral portion of the negative electrode sheet (42 mm width, 429 mm length), an Al ribbon is attached to the innermost peripheral portion of the positive electrode sheet (40 mm width, 406 mm length), and these are separated into separators (44 mm width). , 870 mm long), and wound to make a 12.0 mmφ wound electrode body. After putting this wound electrode body into a battery can and injecting an electrolytic solution, the opening of the battery can is sealed to form a non-cylindrical 14500 type (diameter 14 mm, height 50 mm) as shown in FIG. An aqueous secondary battery was produced. The separator is made of a polyethylene microporous film, and the electrolyte is a mixed solvent of EC and MEC (volume ratio 1: 1) and LiPF ₆ at a concentration of 1 mol / dm ³ . What was dissolved was used.

  Here, the nonaqueous secondary battery shown in FIG. 2 will be described. 101 is a positive electrode (positive electrode sheet), and 102 is a negative electrode (negative electrode sheet). However, in FIG. 2, in order to avoid complication, a metal foil or the like that is a metal support used for manufacturing the positive electrode 101 and the negative electrode 102 is not illustrated. 103 is a separator, and the positive electrode 101 and the negative electrode 102 are spirally wound through the separator 103, and are housed in a battery can 105 together with the electrolyte 104 as an electrode body having a wound structure.

  The battery can 105 is made of iron and nickel-plated on the surface, and an insulator 106 made of polypropylene is disposed at the bottom of the battery can 105 prior to the insertion of the electrode body having the wound structure. The sealing plate 107 is made of aluminum and has a disk shape. A thin portion 107 a is provided at the center of the sealing plate 107, and a pressure introduction port 107 b for allowing the internal pressure of the battery to act on the explosion-proof valve 109 around the thin portion 107 a. As a hole. And the protrusion part 109a of the explosion-proof valve 109 is welded to the upper surface of this thin part 107a, and the welding part 111 is comprised. Note that the thin-walled portion 107a provided on the sealing plate 107 and the protruding portion 109a of the explosion-proof valve 109 are shown only on the cut surface for easy understanding on the drawing, and the contour line behind the cut surface is shown. Is not shown. In addition, the welded portion 111 between the thin wall portion 107a of the sealing plate 107 and the protruding portion 109a of the explosion-proof valve 109 is also shown in an exaggerated state so as to facilitate understanding on the drawing.

  The terminal plate 108 is made of rolled steel, has a nickel plating on the surface, and has a cap shape with a peripheral edge portion. The terminal plate 108 is provided with a gas discharge port 108a. The explosion-proof valve 109 is made of aluminum and has a disk shape. A central portion of the explosion-proof valve 109 is provided with a protruding portion 109a having a tip portion on the power generation element side (lower side in FIG. 2) and a thin portion 109b. Thus, the lower surface of the protruding portion 109a is welded to the upper surface of the thin portion 107a of the sealing plate 107 as described above to constitute the welded portion 111. The insulating packing 110 is made of polypropylene and has an annular shape. The insulating packing 110 is arranged at the upper part of the peripheral portion of the sealing plate 107, and the explosion-proof valve 109 is arranged on the upper portion thereof. The insulating packing 110 insulates the sealing plate 107 from the explosion-proof valve 109. The gap is sealed between the two so that the electrolyte does not leak from between them. The annular gasket 112 is made of polypropylene, the lead body 113 is made of Al, the sealing plate 107 and the positive electrode 101 are connected to each other, an insulator 114 is disposed on the upper part of the wound electrode body, and the negative electrode 102 and the battery can The bottom of 105 is connected by a Ni lead body 115.

  In the battery of FIG. 2, the thin-walled portion 107 a of the sealing plate 107 and the protruding portion 109 a of the explosion-proof valve 109 are in contact with each other at the welded portion 111, and the peripheral portion of the explosion-proof valve 109 and the peripheral portion of the terminal plate 108 are in contact. 101 and the sealing plate 107 are connected by a lead body 113 on the positive electrode side. Therefore, in a normal state, the positive electrode 101 and the terminal plate 108 are connected to the lead body 113, the sealing plate 107, the explosion-proof valve 109, and their welded portions 111. Provides an electrical connection and functions normally as an electrical circuit.

  When an abnormal situation occurs in the battery, such as when the battery is exposed to a high temperature or generates heat due to overcharging, and the internal pressure of the battery increases due to the generation of gas inside the battery, the explosion-proof valve 109 is increased due to the increase in the internal pressure. Is deformed in the internal pressure direction (upward direction in FIG. 2), and along with this, a shearing force acts on the thin portion 107a of the sealing plate 107 integrated with the welded portion 111, and the thin portion 107a is broken. Or after the welded portion 111 between the protruding portion 109a of the explosion-proof valve 109 and the thin-walled portion 107a of the sealing plate 107 is peeled off, the thin-walled portion 109b provided in the explosion-proof valve 109 is cleaved and the gas is discharged from the terminal plate 108. The battery is designed to be discharged from the gas discharge port 108a to the outside of the battery to prevent the battery from bursting.

Example 2
Cylindrical shape as in Example 1, except that the negative electrode support was changed to electrolytic copper having a thickness of 30 μm and through-holes of 0.3 mmφ were formed so that the open area ratio was 50%. A non-aqueous secondary battery was prepared. The tensile strength of the negative electrode support measured in the same manner as in Example 1 was 7.3 N (7.3 N / 15 mm width), and the density of the negative electrode mixture layer was 1.45 g / cm ³ .

Example 3
A cylindrical shape was obtained in the same manner as in Example 1, except that the negative electrode support was changed to electrolytic copper having a thickness of 40 μm and through-holes of 0.3 mmφ were formed so that the open area ratio was 70%. A non-aqueous secondary battery was prepared. The tensile strength of the negative electrode support measured in the same manner as in Example 1 was 7.4 N (7.4 N / 15 mm width), and the density of the negative electrode mixture layer was 1.43 g / cm ³ .

Example 4
A cylindrical support was made in the same manner as in Example 1 except that the positive electrode support was changed to aluminum having a thickness of 30 μm and a through hole having a diameter of 0.3 mm formed so as to have a hole area ratio of 50%. A non-aqueous secondary battery was produced. The tensile strength of the support for the positive electrode measured in the same manner as in Example 1 was 8.3 N (8.3 N / 15 mm width), and the density of the positive electrode mixture layer was 4.0 g / cm ³ .

Example 5
A cylindrical support was made in the same manner as in Example 1 except that the positive electrode support was changed to aluminum having a thickness of 40 μm and a through hole having a diameter of 0.3 mm formed to have a hole area ratio of 70%. A non-aqueous secondary battery was produced. The tensile strength of the positive electrode support measured in the same manner as in Example 1 was 8.0 N (8.0 N / 15 mm width), and the density of the positive electrode mixture layer was 4.0 g / cm ³ .

Example 6
As a negative electrode active material, Si (manufactured by Shin-Etsu Chemical Co., Ltd., average particle diameter: 2 μm), which is an element capable of forming an alloy with Li, and the same carbon particles as used in Example 1 were used at a mass ratio of 70:30. A cylindrical non-aqueous secondary battery was produced in the same manner as in Example 1 except that it was used. The density of the negative electrode mixture layer of the negative electrode according to Example 6 was 1.42 g / cm ³ .

Example 7
Example 1 except that Li _1.02 Ni _0.3 Co _0.29 Mn _0.3 O ₂ (specific surface area 1.75 m ² / g), which is a layered lithium manganese oxide, was used as the positive electrode active material. A cylindrical non-aqueous secondary battery was produced in the same manner as described above. The density of the positive electrode mixture layer of the positive electrode according to Example 7 was 4.0 g / cm ³ .

Comparative Example 1
The negative electrode sheet was changed in the same manner as in Example 1, except that the negative electrode support was changed to electrolytic copper having a thickness of 20 μm and through holes of 0.3 mmφ were formed so that the open area ratio was 50%. Was made. The tensile strength of the negative electrode support measured in the same manner as in Example 1 was 4.6 N (4.6 N / 15 mm width), and the density of the negative electrode mixture layer was 1.43 g / cm ³ .

  An attempt was made to produce a 12.0 mmφ wound electrode body in the same manner as in Example 1 except that the above negative electrode sheet was used. However, the wound electrode body could not be produced because the negative electrode broke during winding.

Comparative Example 2
A positive electrode sheet was prepared in the same manner as in Example 1 except that the positive electrode support was changed to aluminum having a thickness of 20 μm and through-holes of 0.3 mmφ were formed so that the open area ratio was 50%. Produced. The tensile strength of the positive electrode support measured in the same manner as in Example 1 was 4.2 N (4.2 N / 15 mm width), and the density of the negative electrode mixture layer was 4.2 g / cm ³ .

  An attempt was made to produce a 12.0 mmφ wound electrode body in the same manner as in Example 1 except that the above positive electrode sheet was used. However, the wound electrode body could not be produced because the positive electrode broke during winding.

Comparative Example 3
An electrolytic copper foil (thickness 15 μm) having no through holes was used as the negative electrode support, and the composition in the negative electrode mixture layer was (SiO + MCMB): acetylene black: PVDF = 85: 5: 10 (mass ratio). A negative electrode sheet was produced in the same manner as Example 1 except for the above. The tensile strength of the negative electrode support measured in the same manner as in Example 1 was 15 N (15 N / 15 mm width), and the density of the negative electrode mixture layer was 1.3 g / cm ³ .

Further, an aluminum foil (thickness: 15 μm) having no through-hole was used as the positive electrode support, and the composition in the positive electrode mixture layer was Li _1.01 CoO ₂ : acetylene black: PVDF = 89: 5: 6 (mass) A positive electrode sheet was produced in the same manner as in Example 1 except that the ratio was changed. The density of the positive electrode mixture layer was 3.4 g / cm ³ .

  A cylindrical non-aqueous secondary battery was produced in the same manner as in Example 1 except that the above negative electrode and the above positive electrode were used.

  The non-aqueous secondary batteries of Examples 1 to 7 and Comparative Example 3 were subjected to the following discharge capacity measurement and charge / discharge cycle test. The results are shown in Table 1.

<Discharge capacity measurement>
The batteries of Examples 1 to 7 and Comparative Example 3 were allowed to stand at room temperature for 24 hours, charged to 4.2 V at a constant current of 100 mA, and then subjected to constant current and constant voltage charging by applying a constant voltage of 4.2 V for a total of 15 hours. Subsequently, it was discharged to 2.5 V with a constant current of 100 mA (standard charge / discharge). This charge / discharge was performed for 3 cycles, and the discharge capacity at the 3rd cycle was defined as the discharge capacity of the battery.

<Charge / discharge cycle test>
The batteries of Examples 1 to 7 and Comparative Example 3 were charged to 4.2 V with a constant current of 1000 mA, followed by constant current and constant voltage charging for applying a constant voltage of 4.2 V for a total of 1.2 hours, Charging / discharging which discharged to 2.5V with a constant current of 1000 mA was repeated. The number of cycles at the time when the discharge capacity reached 80% of the initial (third cycle) was determined as the battery life.

  As can be seen from Table 1, the non-aqueous secondary batteries of Examples 1 to 7 are higher than the battery of Comparative Example 3 in which the negative electrode support and the positive electrode support are made of a foil having no through holes. A non-aqueous secondary battery having a long capacity and a long life and having both a high capacity and a long life could be obtained.

2 is a schematic plan view of a part of a negative electrode support and a positive electrode support used in Example 1. FIG. It is a longitudinal cross-sectional view which shows an example of the structure of the non-aqueous secondary battery which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Support body 11 Through-hole 101 Positive electrode 102 Negative electrode 103 Separator 104 Non-aqueous electrolyte 105 Battery can

Claims (4)

In a non-aqueous secondary battery capable of inserting and extracting Li ions,
A negative electrode having a negative electrode mixture layer containing at least one active material selected from the group consisting of an element capable of forming an alloy with Li and a compound thereof, and carbon particles capable of occluding and releasing Li ions on both sides of the support And a positive electrode having a positive electrode mixture layer containing a lithium composite oxide on both sides of the support,
The negative electrode support and the positive electrode support have a through-hole penetrating from one surface to the other, and the negative electrode support is made of rolled copper, electroless copper, or a copper alloy. A non-aqueous secondary battery having a thickness of 20 to 40 μm, an aperture ratio of 30 to 70%, and a tensile strength of 5 to 30 N / 15 mm. In a non-aqueous secondary battery capable of inserting and extracting Li ions,
A negative electrode having a negative electrode mixture layer containing at least one active material selected from the group consisting of an element capable of forming an alloy with Li and a compound thereof, and carbon particles capable of occluding and releasing Li ions on both sides of the support And a positive electrode having a positive electrode mixture layer containing a lithium composite oxide on both sides of the support,
The negative electrode support and the positive electrode support have a through-hole penetrating from one surface to the other surface, and the positive electrode support is made of aluminum or an aluminum alloy and has a thickness. Is a non-aqueous secondary battery characterized by having a porosity of 30 to 70%, a tensile strength of 5 to 30 N / 15 mm width.   The non-aqueous secondary battery according to claim 1 or 2, wherein an element capable of forming an alloy with Li in the active material contained in the negative electrode is Si, Sn, Ge, Ag, In, Pb, or Al. The lithium composite oxide contained in the positive electrode is Li _x CoO ₂ , Li _x NiO ₂ , Li _x MnO ₂ , Li _x Co _y Ni _1-y O ₂ , Li _x Co _y M _1-y O ₂ , Li _x Ni _{1-y M y O 2,} Li x Mn y Ni z Co 1-y-z O 2, Li x Mn 2 O 4, and _{Li x Mn 2-y M y} O 4 at least one selected from the group consisting of The non-aqueous secondary battery according to claim 1, which is a seed compound.
However, in the above lithium composite oxide, M is at least one metal element selected from the group consisting of Mg, Mn, Fe, Co, Ni, Cu, Zn, Al, and Cr, and 0 ≦ x ≦ 1 0.1, 0 <y <1.0, 2.0 ≦ z ≦ 2.2.

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