WO2019069356A1 - Electrode group, secondary battery, battery module, electricity storage device, vehicle and flying body - Google Patents

Abstract

Embodiments of the present invention provide: an electrode group which has a long service life or excellent manageability; a secondary battery; a battery module; a storage battery; a vehicle; and a flying body. An electrode group 100 according to one embodiment of the present invention comprises: a center part A which is obtained by rolling up a positive electrode 10, a negative electrode 20 and first separators (30, 40) which are arranged between the positive electrode 10 and the negative electrode 20; and an outer peripheral part B which is obtained by winding a second separator 50 around the outer circumference of the center part A. With respect to this electrode group 100, the total number of turns of the second separator 50 is 3 or more.

Description

Electrode group, secondary battery, battery module, power storage device, vehicle and aircraft

Embodiments relate to an electrode group, a secondary battery, a battery module, a power storage device, a vehicle, and a projectile.

In recent years, chargeable and dischargeable non-aqueous electrolyte batteries such as lithium ion secondary batteries are mainly used as power sources of electric vehicles such as hybrid electric vehicles and plug-in electric vehicles which are rapidly spreading. The lithium ion secondary battery is manufactured, for example, by the following method. After producing an electrode group in which the positive electrode and the negative electrode are wound via a separator, the electrode group is housed in a metal case such as aluminum or an aluminum alloy. Next, a lid is welded to the opening of the case, and a non-aqueous electrolyte is poured into the case from the liquid inlet provided in the lid, and then a sealing member is welded to the liquid inlet to produce a battery unit. . Thereafter, the battery unit is subjected to an initial charge and an aging treatment to obtain a lithium ion secondary battery.

The non-aqueous electrolyte battery is required to have a high input / output and a long life. In order to achieve high input / output, it is effective to thin the separator. However, it has been found that the use of a thin separator deteriorates the life characteristics, and therefore, there is a demand for measures for suppressing the deterioration.

JP, 2013-80698, A

An embodiment provides an electrode group, a secondary battery, a battery module, a storage battery, a vehicle, and a projectile, which are excellent in long life or manageability.

The electrode group according to the embodiment includes an electrode group including a positive electrode, a negative electrode, a central portion around which a first separator disposed between the positive electrode and the negative electrode is wound, and an outer peripheral portion around the outer periphery of the central portion of the second separator. In the above, the total number of turns of the second separator is three or more.

Sectional drawing of the electrode group of embodiment. Sectional drawing of the electrode group of embodiment. The perspective view of the electrode group of embodiment. The perspective expanded view of the electrode group of embodiment. The perspective view of the electrode group of embodiment. Sectional drawing of the electrode group of embodiment. Sectional drawing of the electrode group of embodiment. Sectional drawing of the electrode group of embodiment. The perspective view of the electrode group of embodiment. The perspective view of the rechargeable battery of an embodiment. The expansion | deployment perspective view of the secondary battery of embodiment. The perspective view of the lid of the rechargeable battery of an embodiment. The side view showing the inside of the rechargeable battery of an embodiment. The expanded view of the battery module of embodiment. Sectional drawing of the battery module of embodiment. The schematic diagram of the storage battery of embodiment. BRIEF DESCRIPTION OF THE DRAWINGS The schematic diagram of the vehicle of embodiment. The schematic diagram of the flying object of embodiment.

First Embodiment
The first embodiment relates to an electrode group. The electrode group of the embodiment is a wound electrode group. The electrode group according to the embodiment includes an electrode including a positive electrode, a negative electrode, a central portion around which the first separator disposed between the positive electrode and the negative electrode is wound, and an outer peripheral portion around the outer periphery of the central portion of the second separator. In the group, the total number of turns of the second separator from the end on the outermost side of the central portion is three or more. The cross-sectional schematic diagram of the electrode group 100 is shown in FIG. The electrode group 100 includes a positive electrode 10, a negative electrode 20, two first separators (first A separator 30, first B separator 40), and one second separator 50. The inner region surrounded by the broken line is the central portion A of the electrode assembly 100. A region from the outer side to the outermost periphery of the central portion A of the electrode group 100 is referred to as an outer peripheral portion B. In FIG. 1, the number of turns of the central portion A is three for simplification of the illustration, but for the purpose of increasing the capacity of the electrode group 100, the central portion A is wound several tens of times or more. Is preferred.

In the central portion A, the first separator (30, 40) is disposed between the positive electrode 10 and the negative electrode 20. More specifically, the two first separators (30, 40) are included, and in the center portion A of the electrode group 100, the positive electrode 10, the first A separator 30A, the negative electrode 20 and the first B separator 40 in this order, the negative electrode 20 The first A separator 30, the positive electrode 10 and the first B separator 40, the first A separator 30, the positive electrode 10, the first B separator 40, the negative electrode or the first A separator 30, the negative electrode 20, the first B separator 40, the positive electrode 10 The structure laminated in order of is wound and comprised. In FIG. 1, in the outer peripheral portion B, the second separator 50 is wound around the outer periphery of the central portion A of the electrode group 100 three times. A partially enlarged cross-sectional view of the electrode assembly 100 is shown in FIG. A more detailed structure of the positive electrode 10 and the negative electrode 20 is shown in the enlarged cross-sectional view of the electrode group 100 in FIG. The perspective view of the electrode group 100 is shown in FIG. FIG. 4 is a schematic perspective view of the electrode assembly 100 of FIG. 3 partially unwound. When winding is performed so that the stacked structures do not contact each other, the number of the first separators 30 may be one.

The positive electrode 10 is one of the electrodes of the electrode group 100. The positive electrode 10 includes a positive electrode current collector 11 and a positive electrode active material layer 12. The positive electrode active material layer 12 is disposed on one side or both sides of the positive electrode current collector 11, and the positive electrode active material layer 12 sandwiches the positive electrode current collector 11. In FIGS. 2 and 3, the positive electrode active material layer 12 is provided on both sides of the positive electrode current collector 11. The area of the non-coated portion where the positive electrode active material layer 12 is not provided on the positive electrode current collector 11 at the end of the positive electrode 10 is the positive electrode current collection tab 13.

The positive electrode current collector 11 is a conductive thin film in contact with the positive electrode active material layer 12. As the positive electrode current collector, it is preferable to use a foil, a porous body or a mesh made of a metal such as stainless steel, Al or Ti. In order to prevent corrosion of the current collector due to the reaction between the current collector and the electrolytic solution, the surface of the current collector may be coated with different elements. Typically, the thickness of the positive electrode current collector 11 is preferably 5 μm to 20 μm.

The positive electrode active material layer 12 is a composite material layer containing a positive electrode active material, a binder and a conductive material. The compounding ratio of the positive electrode active material, the conductive agent and the binder in the positive electrode layer is 70% by mass to 96% by mass of the positive electrode active material, 3% by mass to 17% by mass of the conductive material, and 1 the positive electrode binder It is desirable that the content be in the range of mass% to 13 mass%.

As the positive electrode active material, those capable of inserting and extracting lithium can be used. The positive electrode may include one type of positive electrode active material, or may include two or more types of positive electrode active material. Examples of positive electrode active materials include lithium cobalt oxide, lithium manganese composite oxide, lithium nickel composite oxide, lithium cobalt aluminum composite oxide, lithium nickel cobalt manganese composite oxide, spinel lithium manganese nickel composite oxide, lithium Manganese-cobalt composite oxide, lithium iron oxide, lithium fluorinated sulfate, phosphoric acid compound having an olivine crystal structure (for example, Li _x FePO ₄ (0 ≦ x ≦ 1), Li _x MnPO ₄ (0 ≦ x ≦ 1) 2.) Vanadium oxides containing lithium, chalcogen compounds such as titanium disulfide, molybdenum disulfide, iron sulfide and the like are included. Phosphoric acid compounds having an olivine crystal structure are excellent in thermal stability.

An example of the positive electrode active material from which a high positive electrode potential can be obtained is described below. For example, lithium manganese complex oxides such as Li _x Mn ₂ O ₄ (0 <x ≦ 1) and Li _x MnO ₂ (0 <x ≦ 1) of spinel structure, for example Li _x Ni _{1 -y} Al _y O ₂ (0 Lithium nickel aluminum complex oxide such as <x ≦ 1, 0 <y ≦ 1), for example lithium cobalt complex oxide such as Li _x CoO ₂ (0 <x ≦ 1), such as Li _x Ni _{1 -y-z} Co Lithium nickel cobalt composite oxides such as _y Mn _z O ₂ (0 <x ≦ 1, 0 <y ≦ 1, 0 ≦ z ≦ 1), for example, Li _x Mn _y Co _{1 -yO 2} (0 <x ≦ 1) , Lithium manganese cobalt composite oxide such as 0 <y ≦ 1), spinel type lithium manganese nickel composite oxide such as Li _x Mn _2-y Ni _y O ₄ (0 <x ≦ 1, 0 <y <2) , for example, _Li x F _{PO 4 (0 <x ≦ 1} ), the _{Li x Fe 1-y Mn y} PO 4 (0 <x ≦ 1,0 ≦ y ≦ 1), Li x CoPO 4 (0 <x ≦ 1) olivine structure such as And lithium phosphate oxides and fluorinated iron sulfates (for example, LixFeSO ₄ F (0 <x ≦ 1)).

The particles of the positive electrode active material may include a single primary particle, a secondary particle which is an aggregate of primary particles, or both a single primary particle and a secondary particle. The average particle diameter (diameter) of the primary particles of the positive electrode active material is preferably 10 μm or less, and more preferably 0.1 μm to 5 μm. The average particle diameter (diameter) of the secondary particles of the positive electrode active material is preferably 100 μm or less, and more preferably 10 μm to 50 μm.

At least a part of the particle surface of the positive electrode active material may be coated with a carbon material. The carbon material can take the form of a layer structure, a particle structure, or an assembly of particles.

The binder for binding the active material and the conductive agent is, for example, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), fluorine-based rubber, ethylene-butadiene rubber (SBR), polypropylene (PP) , Polyvinylidene fluoride, which is a modified PVdF in which at least one of hydrogen and fluorine of polyethylene (PE), carboxymethylcellulose (CMC), polyimide (PI) and polyacrylimide (PAI) PVdF is substituted with another substituent It includes copolymers of propylene fluoride, terpolymers of polyvinylidene fluoride-tetrafluoroethylene-6 propylene propylene, and acrylic resins. The type of binder can be one or two or more.

Examples of the conductive agent for enhancing the electron conductivity of the positive electrode active material layer 12 and suppressing the contact resistance with the current collector include acetylene black, carbon black, graphite, carbon fibers having an average fiber diameter of 1 μm or less, and the like. Can. The type of conductive agent can be one or two or more.

The positive electrode 10 can be produced, for example, as follows. First, a positive electrode active material, a conductive agent and a binder are dispersed in an appropriate solvent to prepare a slurry. The slurry is applied to the positive electrode current collector 11, and the coating is dried to form the positive electrode active material layer 12 on the positive electrode current collector 11. At this time, a non-coated portion is provided in the longitudinal direction at the end of the positive electrode current collector 11 for the positive electrode current collection tab 13. Here, for example, the slurry may be applied to one surface on the positive electrode current collector 11, or the slurry may be applied to both the one surface on the current collector and the back surface thereof. Next, the positive electrode 10 can be manufactured by applying a press such as a heating press to the positive electrode current collector 11 and the positive electrode active material layer 12, for example.

The negative electrode 20 is one of the electrodes of the electrode group 100. The negative electrode 20 includes a negative electrode current collector 21 and a negative electrode active material layer 22. The negative electrode active material layer 22 is disposed on one side or both sides of the negative electrode current collector 21, and the negative electrode active material layer 22 sandwiches the negative electrode current collector 21. In FIGS. 2 and 3, the negative electrode active material layer 22 is provided on both sides of the negative electrode current collector 21. The region of the non-coated portion where the negative electrode active material layer 22 is not provided on the negative electrode current collector 21 at the end of the negative electrode 20 is the negative electrode current collection tab 23. At one end in the second direction, there is a positive current collecting tab 13, and at the other end in the second direction, there is a negative current collecting tab 23.

The negative electrode current collector 11 is made of, for example, a metal such as Al, Ti, or Cu, or an alloy containing the metal as a main component and one or more elements selected from the group consisting of Zn, Mn, Fe, Cu, and Si. It can be used. In particular, an aluminum alloy foil containing Al as a main component is preferable because it is flexible and has excellent formability. A negative electrode current collector containing a zinc element is also preferable. Here, the form of the zinc element contained in the negative electrode current collector 11 includes elemental zinc (metallic zinc), a compound containing zinc, and a zinc alloy. Typically, the thickness of the negative electrode current collector 11 is preferably 5 μm or more and 20 μm or less.

The negative electrode active material layer 12 is a composite material layer containing a negative electrode active material, a binder and a conductive material. The compounding ratio of the negative electrode active material, the conductive agent, and the binder in the negative electrode active material layer 12 is 70% by mass to 96% by mass of the negative electrode active material, 2% by mass to 20% by mass of the conductive material, and negative electrode binding It is desirable for the agent to be 2% by mass or more and 10% by mass or less. By setting the amount of the conductive material to 2% by mass or more, the current collection performance of the negative electrode mixture layer can be improved. Further, by setting the amount of the negative electrode binder to 2% by mass or more, the binding property between the negative electrode mixture layer and the negative electrode current collector can be enhanced, and excellent cycle characteristics can be expected. On the other hand, it is preferable that the conductive material and the binder be 28 mass% or less, respectively, in order to achieve high capacity.

The negative electrode active material is not particularly limited. As the negative electrode active material, for example, a graphite material or a carbonaceous material (eg, graphite, coke, carbon fiber, spherical carbon, pyrolytic gas-phase carbonaceous material, resin fired body, etc.), chalcogen compound (eg, titanium disulfide, Molybdenum disulfide, niobium selenide, etc., light metal (eg, aluminum, aluminum alloy, magnesium alloy, lithium, lithium alloy etc.), Li _{4 + x} Ti ₅ O ₁₂ (x is a range of −1 ≦ x ≦ 3 by charge and discharge reaction Spinel type lithium titanate represented by the formula, lamsteride type Li _{2 + x} Ti ₃ O ₇ (x changes in the range of −1 ≦ x ≦ 3 by charge and discharge reaction), Ti and P, V, Sn And metal complex oxides containing at least one element selected from the group consisting of Cu, Ni and Fe. As a metal complex oxide containing at least one element selected from the group consisting of Ti and P, V, Sn, Cu, Ni and Fe, for example, TiO ₂ -P ₂ O ₅ , TiO ₂ -V ₂ Mention may be made of O ₅ , TiO ₂ —P ₂ O ₅ —SnO ₂ , TiO ₂ —P ₂ O ₅ —MO (where M is at least one element selected from the group consisting of Cu, Ni and Fe). These metal complex oxides are converted to lithium titanium complex oxides by the insertion of lithium upon charging. It is preferred to include one or more materials in the group consisting of lithium titanium oxide (eg, lithium titanate of spinel type), silicon, tin and the like. The binder of the negative electrode active material layer 22 is common to the binder of the positive electrode active material layer 12. The conductive material of the negative electrode active material layer 22 is common to the conductive material of the positive electrode active material layer 12.

The first separators (30, 40) are porous films disposed between the positive electrode 10 and the negative electrode 20 of the electrode assembly 100. The first separators (30, 40) according to the first embodiment have two layers, ie, the first A separator 30A and the first B separator 30B. In FIGS. 1, 3, 4 and 5, the first B separator 40 is continuously connected to the second separator 50, but is not limited thereto. In the first embodiment, for example, the second separator 50 may be continuously connected to the first A separator 30.

In the electrode group 100, the first A separator 30A, the positive electrode 10A, the first B separator 30B, and the negative electrode 20 are repeatedly stacked in this order. The first separator (30, 40) separates the positive electrode 10 and the negative electrode 20 from each other. The first separator 30 is preferably a thin film. By thinning the first separator 30, the ratio of the electrode active material layer in the electrode group 100 can be increased, which contributes to the improvement of the battery capacity.

The secondary battery is required to have a high capacity. By reducing the thickness of the separator of the electrode group 100 to increase the capacity, the volume ratio of the electrodes in the electrode group 100 can be increased to increase the battery capacity. However, it has been newly found that when the separator between the electrodes is a thin material of, for example, about 12 μm or less, the outer peripheral region where the electrodes are wound is likely to be deteriorated by a large current. When the electrode group is degraded, the resistance between the electrodes increases and the battery characteristics are degraded. Therefore, when a thin separator is used, the initial stage has a high capacity and good characteristics, but in particular, when charge and discharge are repeated under a large current condition, the capacity and output characteristics are likely to be degraded. Therefore, in the embodiment, deterioration is suppressed by further winding the central portion A of the electrode assembly 100 with the second separator 50. Similarly to the first separators (30, 40), when the second separator 50 is made of a thin material, the reduction of the capacity per volume of the electrode assembly 100 is suppressed, and the life at the time of a large current cycle is improved.

The first separators (30, 40) are porous thin insulating layers. The first A separator 30 is in contact with the second separator 50. The first separators (30, 40) include non-woven fabric, film, paper and the like. Examples of the constituent material of the separator include polyolefins such as polyethylene and polypropylene, cellulose, polyester, polyvinyl alcohol, polyimide, polyamide, polyamide imide, polytetrafluoroethylene and vinylon. Examples of preferred separators in terms of thinness and mechanical strength include nonwoven fabrics containing cellulose fibers.

The thickness of the first separator (30, 40) is preferably 4 μm or more and 20 μm or less. Within this range, it is possible to balance the mechanical strength and the reduction of the battery resistance while suppressing the ratio of the separator to the electrode group 100, and to provide a secondary battery with high output and suppressed internal short circuit. Can. Although a separator larger than 20 μm is also usually used, in the embodiment, since the second separator 50 is used, a thinner separator than the usually used separator is preferable. A more preferable thickness of the first separator (30, 40) is 6 μm or more and 12 μm or less.

The porosity of the first separator (30, 40) is 40% or more and 90% or less. The cellulose fiber-containing nonwoven fabric having a porosity of 40% or more has good electrolyte impregnation, and can provide high output performance from low temperature to high temperature. When the porosity of the first separator (30, 40) is too high, handling becomes difficult, and the positive electrode 10 and the negative electrode 20 tend to be short-circuited. Therefore, the porosity of the first separator (30, 40) is preferably 60% to 80% or 50% to 75% from the viewpoint of productivity.

The second separator 50 is not present between the positive electrode 10 and the negative electrode 20, and is wound multiple times on the first separator (the first A separator 30 or the first B separator 40). The second separator 50 is included in the outer peripheral portion B outside the central portion A of the electrode group 100. The second separator 50 is wound around the center A. In the first embodiment, the first A separator 30A or the first B separator 40 and the second separator 50 are one continuous sheet. In FIG. 1, the first B separator 40 and the second separator 50 are connected at the boundary between the central portion A and the outer peripheral portion B, which are coating ends on the outer peripheral side of the electrode group 100. The boundary between the central portion A and the outer peripheral portion B starts to be wound among the coated end of the positive electrode active material layer 12 and the coated end of the negative electrode active material layer 22 in the first direction on the outer peripheral side when the electrode assembly 100 is unwound. It is a coated end closer to the side.

In the first embodiment, since the second separator 50 is a sheet connected to the first separators (30, 40), physical properties such as thickness, material, porosity, etc. can be obtained by combining the first separators (30, 40) with the first separator (30, 40). The two separators 50 are the same. The second separator 50 is a porous thin insulating layer. The second separator 50 includes non-woven fabric, film, paper and the like. Examples of the constituent material of the separator include polyolefins such as polyethylene and polypropylene, and cellulose. Examples of preferred separators in terms of thinness and mechanical strength include nonwoven fabrics containing cellulose fibers.

The second separator 50 preferably has a thickness of 4 μm to 20 μm. It is possible to provide a secondary battery with little deterioration by sufficiently impregnating the electrolyte while suppressing the ratio of the separator to the electrode group 100 within this range. Although a separator larger than 20 μm is also generally used, in the embodiment, since the outer peripheral portion B is wound, a separator thinner than the separator generally used is preferable. The more preferable thickness of the second separator 50 is 6 μm or more and 12 μm or less.

The porosity of the second separator 50 is 40% or more and 90% or less. The cellulose fiber-containing non-woven fabric having a porosity of 40% or more has good electrolyte impregnation. If the porosity of the second separator 50 is too high, handling becomes difficult. Therefore, the porosity of the second separator 50 is preferably 60% or more and 80% or less, or 50% or more and 75% or less from the viewpoint of productivity.

The total number of turns of the second separator 50 is preferably 3 or more. By winding three or more turns, the liquid retaining property at the outermost periphery of the central portion A of the electrode group 100 is improved, and deterioration of the electrode at the end of winding of the central portion A of the electrode group 100 can be prevented. The second separator 50 preferably has the central portion A wound continuously from the outermost periphery of the electrode assembly 100. The electrolyte that has permeated from the second separator 50 is accumulated in the space between the end on the outer peripheral side of the central portion A and the second separator 50, and the electrolyte in the space is easily held by the second separator 50. Deterioration can be prevented.

If the one- or two-round separator is wound on the outside of the central portion A, the effect of suppressing the deterioration of the active material layer is not very high. If the total number of turns is less than three, the liquid retaining property at the outermost periphery of the central portion A of the electrode group 100 is not improved so much, and the effect of suppressing the deterioration of the active material layer on the outer peripheral side of the central portion A is not sufficient. Absent. It is preferable from the viewpoint of protection of the active material layer as the total number of turns of the second separator 50 increases. However, as the total number of turns of the second separator 50 increases, the amount of submembers in the battery increases, and the energy density decreases. From the viewpoint of battery capacity, it is not preferable that the total number of turns is too large. Therefore, the total number of turns of the second separator 50 is more preferably 4 or more, 5 or more, and 10 or more. The total number of turns of the second separator 50 is preferably 40 or less and 30 or less, and more preferably 20 or less from the viewpoint of the initial capacity and the capacity after cycling (high load). When the number of turns of the second separator 50 increases, the number of air gaps in the battery decreases, so the battery is easily expanded at the time of gas generation, leading to a decrease in capacity and an increase in resistance at the life test. The number of times is preferably 20 or less. It is preferable from the viewpoint of preventing deterioration of the secondary battery to wind the thin second separator 50 three or more times rather than winding the thick second separator 50 only once or twice.

The total number of turns is the number of turns from where the boundary between the central portion A and the outer peripheral portion B is crossed. The portion where the number of turns of the second separator 50 does not exceed one turn, for example, the portion where the center portion A is only half a turn, is not added to the number of turns. That is, the number of turns is rounded off after the decimal point. The second separator 50 is also thin in the same manner as the first separators (30, 40), and is therefore preferable in that the volume occupied in the electrode group 100 is small. The end of the second separator 50 is preferably fixed by an adhesive tape (not shown).

Further, as shown in FIG. 5, it is preferable that an identification code 60 be printed on the surface (uppermost surface) of the second separator 50 at the outermost periphery of the electrode group 101 of the first embodiment. Since the outermost periphery of the electrode group 101 is the second separator 50, even if the identification code is printed here, the battery characteristics are not adversely affected. For example, when the identification code is printed directly on the electrode active material layer, it is difficult to print and it is not preferable to perform unnecessary treatment on the electrode active material layer at the time of preparation. The outer peripheral portion of the electrode group 101 is a separator wound a plurality of times, so that a clear identification code 60 can be easily printed. From the viewpoint of clearly printing the identification code 60, the total number of turns of the second separator 50 is preferably 5 or more. The identification code 60 preferably includes one of a one-dimensional code and a two-dimensional code. Since the two-dimensional code 60 has a complicated shape, the electrode group 101 capable of printing the clear identification code 60 is preferable. The identification code 60 includes, for example, information related to the production of the electrode group 101.

The form of the electrode group can be examined, for example, by removing the electrolyte of the electrode group taken out of the battery case and observing the cross section. The porosity may be measured by cutting the separator from the unrolled electrode group. In addition, the composition of the separator and the electrode may be obtained by cutting or scraping the respective layers and performing elemental analysis or structural analysis. For observation, it is preferable to carry out magnified observation using an optical microscope.

Second Embodiment
The second embodiment is a modification of the first embodiment. The cross-sectional schematic diagram of the electrode group 101 of 2nd Embodiment is shown in FIG. The electrode group 102 shown in FIG. 6 includes a positive electrode 10, a negative electrode 20, two first separators 30 (first A separator 30, first B separator 40) and two second separators (second A separator 50, second B separator 70). ). It differs from the electrode assembly 100 of the first embodiment in that two first separators (30, 40) are both connected continuously with the second separator (50, 70). Except this point, the first embodiment and the second embodiment are common. The total number of turns of the second separator (50, 70) is the sum of the number of turns of the second A separator 50 and the number of turns of the second B separator 70.

When increasing the total number of turns of the second separator (50, 70) in the outer peripheral portion B, if the second separator (50, 70) has two layers, the electrode assembly 101 according to the first embodiment has the same number of turns. This is suitable for increasing the total number of turns since the number of turns in the manufacturing process is halved compared to the above. Similarly to the electrode group 100 of the first embodiment, the electrode group 102 of the second embodiment is excellent in capacity characteristics and cycle characteristics (high current) even when a thin separator is used. Similarly to the electrode group 101 of the first embodiment, it is preferable that the identification code 60 be printed on the electrode group 102 of the second embodiment.

Third Embodiment
The third embodiment is a modification of the first embodiment. The cross-sectional schematic diagram of the electrode group 103 of 3rd Embodiment is shown in FIG. The electrode group 103 shown in FIG. 7 has a positive electrode 10, a negative electrode 20, two first separators 30 (first A separator 30, first B separator 40) and one second separator 80. The electrode group 100 is different from the electrode group 100 of the first embodiment in that a second separator 80 which is not connected to the first separators (30, 40) is wound around the outer periphery of the central portion A. The total number of turns of the second separator 80 is the number of turns of the second separator 80.

In the electrode group 103 of the third embodiment, the central portion A of the electrode group 103 is wound by a separator other than the first separators (30, 40). The second separator 80 is common to the first separators (30, 40) and the second separator 50 of the first embodiment. The first separator (30, 40) of the third embodiment may be an inorganic particle layer in addition to the nonwoven fabric, the film, the paper and the like. The thickness of the inorganic particle layer is preferably 4 μm or more and 20 μm or less as in the case of the organic separator. The inorganic particle layer contains oxide particles, a thickener, and a binder. As the oxide particles, metal oxides such as aluminum oxide, titanium oxide, magnesium oxide, zinc oxide and barium sulfate can be used. Carboxymethylcellulose can be used as a thickener. As the binder, methyl acrylate, an acrylic copolymer containing it, styrene butadiene rubber (SBR), etc. can be used. Except for these points, the first embodiment and the third embodiment are common.

Further, how to count the number of turns of the second separator 80 is different from that of the first embodiment. The number of turns of the second separator 80 is the number of times the second separator 80 winds the central portion A regardless of the position of the end of the central portion A of the electrode group 103. In the schematic sectional view of FIG. 7, since the second separator 80 is strongly wound three times on the outer periphery of the central portion A of the electrode group 103, the number of windings of the second separator 80 is three.

In the electrode group 103 of the third embodiment, different separator materials can be selected for the central portion A and the outer peripheral portion B. For example, by making the second separator 80 thinner than the first separators (30, 40) of the central portion A, the number of turns of the outer peripheral portion B is reduced while reducing the influence on the cycle characteristics due to the thinning of the central portion A separator. Can be increased. In the electrode group 103 of the third embodiment, the options of the separator material also expand, so the electrode group 103 can be designed more freely. Further, as in the first embodiment, it is preferable that the identification code 60 be printed on the outermost second separator 80. Alternatively, the identification code 60 may be printed on the second separator 80 in advance, and the central portion A of the electrode group 103 may be wound with the second separator 80 having the identification code 60 printed thereon.

Fourth Embodiment
The fourth embodiment is a modification of the third embodiment. The cross-sectional schematic diagram of the electrode group 104 of 4th Embodiment is shown in FIG. The electrode group 104 shown in FIG. 8 has the stacked positive electrode 10, negative electrode 20, two first separators 30 (first A separator 30, first B separator 40) and one second separator 80. The central part of the electrode group 104 is different from the electrode group 100 of the third embodiment in that the center part of the electrode group 104 is not a wound type but a laminated type in which a positive electrode 10, a 1B separator 40, a negative electrode 20, and a 1A separator 30 are sequentially laminated. The total number of turns of the second separator 80 is the number of turns of the second separator 80.

The stacked electrode group 104 has many ends of the positive electrode 10 and the negative electrode 20 as compared with the wound type, and therefore the effect of preventing deterioration of the active material layer by the second separator 80 in the outer peripheral portion B is large. Although FIG. 8 shows an electrode group of a modification of the third embodiment, the present invention is not limited to this, and one or both of the first separator and the first separator as in the first and second embodiments. The second separator may be connected.

Fifth Embodiment
The electrode group of the fifth embodiment is a modification of the first embodiment. A perspective view of the electrode group 105 of the fifth embodiment is shown in FIG. The electrode group 105 includes a second separator 90 in which a central portion A in which a laminate having a first separator is wound between the positive electrode 10 and the negative electrode 20 and an outer peripheral portion B of the central portion A is wound. An identification code 60 is printed on the outermost periphery of the image. The non-coated portion of the positive electrode is the positive electrode current collecting tab 13, and the non-coated portion of the negative electrode 20 is the negative electrode current collecting tab 23. The number of turns of the second separator 90 is at least one. The outermost periphery of the electrode group 105 of the fifth embodiment is wound with the second separator 90, so printing of the identification code 60 is possible. Since the identification code 60 is printed on the electrode group 105 of the fifth embodiment, it is preferable in terms of excellent controllability. The laminated electrode group may be used as the center of the electrode group, and the outer periphery thereof may be wound with the second separator 90 and the identification code 60 may be attached.

Sixth Embodiment
The sixth embodiment relates to a secondary battery. The secondary battery of the sixth embodiment uses any of the electrode groups of the first, second, third, fourth and fifth embodiments. The use of the electrode group according to any one of the first, second, third and fourth embodiments provides excellent capacity characteristics and cycle characteristics, and the use of the electrode group according to the fifth embodiment provides excellent manageability. preferable.

10 to 12 show a secondary battery 200 of the sixth embodiment. The secondary battery 200 includes the packaging material 201, the electrode group 202 (100, 101, 102, 103, 105), the positive electrode lead 203, the negative electrode lead 204, the lid 205, the positive electrode terminal 206, the negative electrode terminal 207, the positive electrode backup lead 208, the negative electrode The back-up lead 209, the positive electrode insulating cover 210, the negative electrode insulating cover 211, the positive electrode gasket 212, the negative electrode gasket 213, the safety valve 214, the electrolyte injection port 215, and an electrolyte (not shown) are provided. The electrolytic solution is preferably present in the outer package 201 and filled in the outer package 201. In addition, the secondary battery of embodiment is a secondary battery which can be charged / discharged, for example. FIG. 10 is a perspective view of the secondary battery of the embodiment. FIG. 11 is an exploded perspective view of the secondary battery of the embodiment. Figure 12 It is a perspective view of a lid of a rechargeable battery of an embodiment. FIG. 13 is a side view showing the inside of the secondary battery of the embodiment. Although FIG. 10 shows a square secondary battery, it is not limited to the square. Further, in the sixth embodiment, the wound electrode group is accommodated, but a stacked electrode group as in the fourth embodiment may be accommodated.

The packaging material 201 may, for example, be a laminate film or a metal container. The shape may, for example, be flat, square, cylindrical, coin, button, sheet or laminate.

As the laminate film, a multilayer film in which a metal layer is interposed between resin films can be used. The metal layer is preferably aluminum foil or aluminum alloy foil in order to reduce the weight. The resin film can use polymeric materials, such as polypropylene (PP), polyethylene (PE), nylon, polyethylene terephthalate (PET), for example. The laminated film can be sealed by heat fusion and can be formed into the shape of the exterior material. The thickness of the laminate film is preferably, for example, 0.2 mm or less.

As the metal container, aluminum, aluminum alloy, iron, stainless steel and the like can be used. The lid may be made of aluminum, aluminum alloy, iron, stainless steel or the like. The lid and the sheathing material are preferably formed of the same type of metal. The thickness of the metallic container is preferably, for example, 0.5 mm or less.

The positive electrode current collecting tab 216 is bundled by the positive electrode backup lead 208 and electrically connected to the positive electrode terminal 206 through the positive electrode lead 203. In addition, the negative electrode current collection tab 217 is bundled by the negative electrode backup lead 209 and electrically connected to the negative electrode terminal 207 via the negative electrode lead 204.

The electrolyte is a gel electrolyte in which a polymer material is complexed with a solution containing an electrolyte salt and a non-aqueous solvent present in the packaging material 201, a solution containing an electrolyte salt and water, or a solution containing water.

The electrolyte salt contained in the non-aqueous solution is, for example, LiPF ₆ , LiBF ₄ , Li (CF ₃ SO ₂ ) ₂ N (bistrifluoromethanesulfonylamide lithium; commonly called LiTFSI), LiCF ₃ SO ₃ (commonly called LiTFS), Li (C) _{2 F 5 SO 2) 2 N} ( bis pentafluoroethanesulfonyl amide lithium; called _{LiBETI), LiClO 4, LiAsF 6} , LiSbF 6, LiB (C 2 O 4) 2 ( bis oxa Lato lithium borate; called LiBOB), difluoro Lithiums such as (trifluoro-2-oxide-2-trifluoro-methylpropionato (2-)-0,0), LiBF ₂ OCOOC (CF ₃ ) ₂ (lithium borate; commonly called LiBF ₂ (HHIB)) Salt can be used. These electrolyte salts may be used alone or in combination of two or more. In particular, LiPF ₆ and LiBF ₄ are preferred. For lithium salts, supporting salts that conduct ions can be used. For example, lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate, an imide based support salt and the like can be mentioned. The lithium salt may contain one or more kinds.

The non-aqueous electrolyte salt concentration is preferably in the range of 0.5 mol / L to 3 mol / L, and more preferably in the range of 0.7 mol / L to 2 mol / L. Such regulation of the electrolyte concentration makes it possible to further improve the performance when a high load current is applied while suppressing the influence of the viscosity increase due to the increase of the electrolyte salt concentration.

The non-aqueous solvent is not particularly limited. For example, cyclic carbonate such as propylene carbonate (PC) or ethylene carbonate (EC), diethyl carbonate (DEC) or dimethyl carbonate (DMC) or methyl ethyl carbonate (MEC) Or linear carbonates such as dipropyl carbonate (DPC), 1,2-dimethoxyethane (DME), γ-butyrolactone (GBL), tetrahydrofuran (THF), 2-methyltetrahydrofuran (2-MeHF), 1,3-dioxolane , Sulfolane, acetonitrile (AN) can be used. These solvents may be used alone or in combination of two or more. Nonaqueous solvents comprising cyclic carbonates and / or linear carbonates are preferred.

The electrolyte salt contained in the aqueous solution is LiCl, LiBr, LiOH, Li ₂ SO ₄ , LiNO ₃ , LiN (SO ₂ CF ₃ ) ₂ (lithium trifluoromethanesulfonylamide; commonly called LiTFSA), LiN (SO ₂ C ₂ F ₅₎ ) ₂ (lithium bis pentafluoroethanesulfonyl amide; called _{LiBETA), LiN (SO 2 F} ) 2 ( lithium bis fluorosulfonyl amide; called LiFSA), and the like LiB [(OCO) _{2] 2.} The type of lithium salt to be used can be one or two or more. Examples of the polymer material contained in the aqueous gel electrolyte include polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polyethylene oxide (PEO) and the like.

The electrolyte salt concentration of the aqueous system is preferably 1 mol / L or more and 12 mol / L or less, more preferably 112 mol / L or more and 10 mol / L or less. In order to suppress the electrolysis of the electrolytic solution, LiOH or Li ₂ SO ₄ can be added to adjust the pH. The pH value is preferably 3 or more and 13 or less, more preferably pH 4 or more and 12 or less.

The positive electrode lead 203 is a conductive member which physically connects the positive electrode terminal 206 and the positive electrode backup lead 820 as shown in FIGS. The positive electrode lead 203 is a conductive member such as aluminum or an aluminum alloy. The positive electrode lead 203 and the positive electrode backup lead 208 are preferably joined by, for example, laser welding.

The negative electrode lead 204 is a conductive member which physically connects the negative electrode terminal 207 and the negative electrode backup lead 209 as shown in FIGS. The negative electrode lead 204 is a conductive member such as aluminum or an aluminum alloy. The negative electrode lead 204 and the negative electrode backup lead 209 are preferably joined by, for example, laser welding.

The lid 205 is a lid of the packaging material 201 accommodating the electrode group 202 as shown in FIGS. 10 to 13, and has a positive electrode terminal 206 and a negative electrode terminal 207. The lid 205 includes a positive electrode terminal 206, a negative electrode terminal 207, a negative electrode insulating cover 211, a positive electrode gasket 212, a negative electrode gasket 213, a safety valve 214, and an electrolyte injection port 215. The lid 205 is a molded member made of metal such as aluminum, aluminum alloy, iron or stainless steel, or an alloy. It is preferable that the lid 205 and the package 201 be laser-welded or be bonded by a sealing material such as an adhesive resin.

The positive electrode terminal 206 is an electrode terminal for the positive electrode of the secondary battery provided on the lid 205 as shown in FIGS. 10 to 13. The positive electrode terminal 206 is formed of a conductive member such as aluminum or an aluminum alloy. The positive electrode terminal 206 is fixed to the lid 205 via the insulating positive electrode gasket 212. The positive electrode terminal 206 is electrically connected to the positive electrode current collection tab 216 via the positive electrode lead 203 and the positive electrode backup lead 208.

The negative electrode terminal 207 is an electrode terminal for the negative electrode of the secondary battery provided on the lid 205 as shown in FIGS. 10 to 13. The negative electrode terminal 207 is formed of a conductive member such as aluminum or an aluminum alloy. The negative electrode terminal 207 is fixed to the lid 205 via the insulating negative electrode gasket 213. The negative electrode terminal 207 is electrically connected to the negative electrode current collection tab 217 via the negative electrode lead 204 and the negative electrode backup lead 209.

The positive electrode backup lead 208 is a conductive member which bundles the positive electrode current collection tab 216 and is fixed to the positive electrode lead 203 as shown in FIGS. The positive electrode backup lead 208 and the positive electrode current collection tab 216 are preferably joined by ultrasonic bonding.

The negative electrode backup lead 209 is a conductive member which bundles the negative electrode current collection tab 217 and is fixed to the negative electrode lead 204 as shown in FIGS. The negative electrode backup lead 209 and the negative electrode current collection tab 217 are preferably joined by ultrasonic bonding.

The positive electrode insulating cover 210 is an insulating member which covers the positive electrode lead 203 and the positive electrode backup lead 208 as shown in FIG. The positive electrode insulating cover 210 is joined at one end including the positive electrode current collecting tab 216 of the electrode group 202. The positive electrode insulating cover 210 is preferably an insulating and heat resistant member. The positive electrode insulating cover 210 is preferably a resin molded body, a molded body of a material mainly made of paper, or a member obtained by coating a molded body of a material mainly made of paper with a resin. It is preferable to use a polyethylene resin or a fluorine resin as the resin. The shape of the positive electrode insulating cover 210 is such that the positive electrode lead 203 and the positive electrode backup lead 208 are in contact with the packaging material 201. By using the positive electrode insulating cover 210, the positive electrode and the exterior material 201 are insulated, and the current collection tab area (the current collection tab, the lead, the backup lead) can be protected from the external impact.

The negative electrode insulating cover 211 is an insulating member which covers the negative electrode lead 204 and the negative electrode backup lead 209 as shown in FIG. The negative electrode insulating cover 211 is bonded to one end portion of the electrode group 202 including the negative electrode current collecting tab 217. The material, shape, and the like of the negative electrode insulating cover 211 are the same as those of the positive electrode insulating cover 210. The description common to the positive electrode insulating cover 210 and the negative electrode insulating cover 211 is omitted.

The positive electrode gasket 212 is a member which insulates the positive electrode terminal 206 and the exterior material 201 as shown in FIGS. The positive electrode gasket 212 is preferably a solvent-resistant, flame-retardant resin molded body. For example, a polyethylene resin or a fluorine resin is used for the positive electrode gasket 212.

The negative electrode gasket 213 is a member which insulates the negative electrode terminal 207 and the packaging material 201 as shown in FIGS. The negative electrode gasket 213 is preferably a solvent-resistant, flame-retardant resin molded body. For the negative electrode gasket 213, for example, a polyethylene resin or a fluorine resin is used.

The safety valve 214 is a member that is provided on the lid as shown in FIGS. 10 to 13 and that functions as a pressure reducing valve that reduces the pressure in the exterior material 201 when the internal pressure in the exterior material 201 rises. The safety valve 214 is preferably provided, but can be omitted in consideration of conditions such as a battery protection mechanism and an electrode material.

The electrolyte injection port 215 is a hole for injecting the electrolyte as shown in FIGS. 10 to 12. After the injection of the electrolytic solution, it is preferable to be sealed with a resin or the like.
Although not shown in the drawings, it is preferable that each member be fixed or connected using an insulating adhesive tape.

Seventh Embodiment
The seventh embodiment relates to a battery module. In the seventh embodiment, the secondary battery of the sixth embodiment using the electrode group of any of the first, second, third, fourth and fifth embodiments is a unit cell (cell). Use as one or more. The use of the electrode group according to any one of the first, second, third and fourth embodiments provides excellent capacity characteristics and cycle characteristics, and the use of the electrode group according to the fifth embodiment provides excellent manageability. preferable. When the battery module includes a plurality of single cells, the single cells are electrically connected in series, in parallel, or in series and in parallel.

The battery module 300 will be specifically described with reference to the perspective development view of FIG. 14 and the cross-sectional view of FIG. In the battery module 300 shown in FIG. 14, the secondary battery 200 shown in FIG. 10 is used as the single battery 301. The cross-sectional view of FIG. 15 is a cross-section including the positive electrode terminal 303B and the negative electrode terminal 306B in the perspective development view of FIG.

The plurality of unit cells 301 are provided outside the battery case, with the positive electrode terminals 303 (303A and 303B) provided on the positive electrode gasket 302, the safety valve 304, and the negative electrode terminals 306 (306A and 306B) provided on the negative electrode gasket 305. Have. The single cells 301 shown in FIG. 14 are arranged to be alternately arranged. The unit cells 301 shown in FIG. 14 are connected in series, but may be connected in parallel by changing the arrangement method or the like.

The unit cell 301 is accommodated in the lower case 307 and the upper case 308. The upper case 308 is provided with power source input / output terminals 309 and 310 (positive electrode terminal 309 and negative electrode terminal 310) of the battery module. An opening 311 is provided in the upper case 308 in accordance with the positions of the positive electrode terminal 303 and the negative electrode terminal 306 of the unit cell 301, and the positive electrode terminal 303 and the negative electrode terminal 306 are exposed from the opening 311. The exposed positive electrode terminal 303A is connected to the negative electrode terminal 306A of the adjacent single cell 301 by the bus bar 312, and the exposed negative electrode terminal 306A is connected to the positive electrode terminal 303A of the adjacent single cell 301 and the bus bar 312 Connected by. The positive terminal 303 B not connected by the bus bar 312 is connected to the positive terminal 314 A provided on the substrate 313, and the positive terminal 314 A is connected to the positive power input / output terminal 309 via the circuit on the substrate 313. There is. In addition, the negative terminal 306B not connected by the bus bar 312 is connected to the negative terminal 314B provided on the substrate 313, and the negative terminal 314B is connected to the negative power input / output terminal 310 via the circuit on the substrate 313. doing. The power input / output terminals 309 and 310 are connected to a charging power source and a load (not shown) to charge and use the battery module 300. The upper case 308 is sealed by a lid 315. It is preferable that the substrate 313 be provided with a charge and discharge protection circuit. In addition, a configuration may be appropriately added such as a configuration in which information such as deterioration of the single battery 301 can be output from a terminal (not shown).

Eighth Embodiment
The eighth embodiment relates to a power storage device. The battery module 300 of the seventh embodiment can be mounted on the power storage device 400. A power storage device 400 shown in the conceptual view of FIG. 16 includes a battery module 300, an inverter 402, and a converter 401. The external AC power supply 403 is DC converted by the converter 401, the battery module 300 is charged, AC converted by the inverter 402 of the DC power supply from the battery module 300, and electricity is supplied to the load 404 connected to the storage device 400. ing. By using the power storage device 400 of the present configuration having the battery module 300 of the embodiment, a power storage device having excellent battery characteristics is provided. By using the power storage device 400 of the present configuration having the battery module 300 of the embodiment, a power storage device having excellent battery characteristics and manageability is provided.

Ninth Embodiment
The ninth embodiment relates to a vehicle. The vehicle of the ninth embodiment uses the battery module 300 of the seventh embodiment. The configuration of the vehicle according to the present embodiment will be briefly described using a schematic view of the vehicle 500 in FIG. The vehicle 500 includes a battery module 300, a vehicle body 501, a motor 502, wheels 503, and a control unit 504. The battery module 300, the motor 502, the wheels 503, and the control unit 504 are disposed in the vehicle body 501. The control unit 504 converts the power output from the battery module 300 or adjusts the output. The motor 502 rotates the wheels 503 using the power output from the battery module 300. Vehicle 500 also includes an electric vehicle such as a train and a hybrid vehicle having another drive source such as an engine. The battery module 400 may be charged by the regenerative energy from the motor 502. What is driven by the electrical energy from the battery module 300 is not limited to the motor, and may be used as a power source for operating the electric device included in the vehicle 500. In addition, it is preferable to obtain regenerative energy at the time of deceleration of the vehicle 500 and charge the battery module 300 using the obtained regenerative energy. By adopting the vehicle 500 of the present configuration having the battery module 300 of the embodiment, a vehicle excellent in battery characteristics and manageability is provided.

Tenth Embodiment
The tenth embodiment relates to a projectile (for example, a multicopter). The projectile of the tenth embodiment uses the battery module 300 of the seventh embodiment. The configuration of the projectile according to this embodiment will be briefly described using a schematic view of a project (quadcopter) 600 of FIG. The projectile 600 has a battery module 300, an airframe skeleton 601, a motor 602, a rotary wing 603 and a control unit 604. The battery module 300, the motor 602, the rotary wings 603 and the control unit 604 are disposed on the airframe skeleton 601. The control unit 604 converts the power output from the battery module 300 and adjusts the output. The motor 602 rotates the rotor 603 using the power output from the battery module 300. By using the projectile 600 of the present configuration having the battery module 300 of the embodiment, a projectile excellent in battery characteristics and manageability is provided.

Hereinafter, a method of manufacturing an electrode group and a secondary battery according to an embodiment of the present invention will be described by way of specific examples. In addition, the Example mentioned later is an example of the leading embodiment of this invention, and this invention is not limited only to a following example.

Example 1
[Production of positive electrode]
Lithium nickel cobalt manganese complex oxide LiNi _1/3 Co _1/3 Mn _1/3 O ₂ and lithium cobalt complex oxide LiCoO ₂ were prepared as positive electrode active materials. These were mixed so that LiNi _1/3 Co _1/3 Mn _1/3 O ₂ and LiCoO ₂ were 2: 1, to obtain an active material mixture. The active material mixture, carbon black as a conductive agent, and polyvinylidene fluoride as a binder were mixed at a mass ratio of 100: 5: 3. The mixture thus obtained was added to N-methyl-2-pyrrolidone as a solvent, and this was kneaded and stirred by a planetary mixer to prepare a positive electrode slurry. The positive electrode slurry was applied and dried so as to form a partially uncoated part on the front and back of a 12 μm thick aluminum foil. Slitting was performed so as to have a coated width of 90 mm and an uncoated width of 25 mm, and then compression was performed by a roll press to produce a positive electrode.

[Fabrication of negative electrode]
Lithium titanate Li ₄ Ti ₅ O ₁₂ was prepared as a negative electrode active material. The active material, carbon black as a conductive agent, and polyvinylidene fluoride as a binder were mixed at a mass ratio of 100: 5: 5. The mixture thus obtained was added to N-methyl-2-pyrrolidone as a solvent, and this was kneaded and stirred by a planetary mixer to prepare a negative electrode slurry. The negative electrode slurry was applied and dried so as to form a partially uncoated part on the front and back of a 12 μm thick aluminum foil. Slitting was performed so as to have a coated width of 95 mm and an uncoated width of 20 mm, and then compression was performed by a roll press to produce a negative electrode.

[Preparation of wound electrode group]
The negative electrode produced as described above and the positive electrode produced as described above were laminated, and a cellulose separator was interposed between the positive electrode and the negative electrode to obtain a laminate. The separator used at this time had a film thickness of 10 μm and a porosity of 60%. The laminate was then transferred to a winding device, and the entire laminate was folded and wound in a spiral. After winding the electrode, the separator was wound 10 times to obtain an electrode group. This separator is connected to the separator used when winding the electrode group. The wound electrode group obtained in this manner was pressed to obtain a flat wound electrode group.

[Assembly of battery]
A sealing body provided with a positive electrode lead connected to the positive electrode terminal and a negative electrode lead connected to the negative electrode terminal was prepared. The positive electrode uncoated portion disposed at one end of the wound electrode group and the positive electrode lead were ultrasonically bonded. Moreover, the negative electrode uncoated part arrange | positioned at the other end of a winding-type electrode group and the negative electrode lead were ultrasonically bonded. This was inserted into and fitted into the outer can, and the sealing body and the outer can were welded in this manner to obtain a battery unit.

[Injection of electrolyte and completion of secondary battery]
The solvent was adjusted by mixing ethylene carbonate and dimethyl carbonate 1: 1. In this solvent, lithium hexafluorophosphate LiPF ₆ as an electrolyte was dissolved to a concentration of 1 mol / L. Thus, a non-aqueous electrolyte was obtained. The electrolytic solution was injected into the battery unit from a liquid injection port provided in the sealing body. After the injection, a sealing member made of aluminum was fitted into the liquid inlet, and the periphery of the sealing member was welded to the sealing body. Thus, the secondary battery of Example 1 was completed. The initial capacity of the produced secondary battery and the cycle capacity after 1000 cycles at 55 ° C. were determined. Further, the resistance between the positive electrode and the negative electrode in the initial stage and after 1000 cycles was determined, and the rate of change in resistance was determined. The secondary battery was charged and discharged at a charge and discharge rate of 2C. Tables 1 and 2 show the first separator (center portion), the second separator (peripheral portion), the total number of turns of the separator in the peripheral portion, the thickness of the separator, the porosity of the separator, the positive electrode active material, The negative electrode active material, the capacity retention rate after the cycle test, the resistance change rate and the initial capacity are collectively shown.

(Example 2)
A secondary battery was produced in the same manner as in Example 1 except that the separator in the outer peripheral portion was not connected to the electrode group in the central portion. In addition, the separator of a center part and an outer peripheral part is the same separator.

(Example 3)
A secondary battery was produced in the same manner as in Example 1 except that the number of separator windings in the outer peripheral portion was 4 turns.

(Example 4)
A secondary battery was produced in the same manner as in Example 1 except that the number of separator windings in the outer peripheral portion was set to 20.

(Example 5)
A secondary battery was produced in the same manner as in Example 1 except that the film thickness of the separator was 12 μm.

(Example 6)
A secondary battery was produced in the same manner as in Example 1 except that the film thickness of the separator was 6 μm.

(Example 7)
A secondary battery was produced in the same manner as in Example 1 except that the porosity of the separator was 40%.

(Example 8)
A secondary battery was produced in the same manner as in Example 1 except that the porosity of the separator was 80%.

(Example 9)
A secondary battery was produced in the same manner as in Example 1 except that the number of turns of the separator in the outer peripheral portion was set to 30.

(Example 10)
A secondary battery was produced in the same manner as in Example 1 except that the number of turns of the separator in the outer peripheral portion was set to 30.

(Example 11)
A secondary battery was produced in the same manner as in Example 1 except that the number of turns of the separator in the outer peripheral portion was changed to 40.

(Example 12)
A secondary battery was produced in the same manner as in Example 1 except that a polyolefin porous separator having a porosity of 50% and a thickness of 6 μm made of polyethylene was used as the separator.

(Example 13)
A secondary battery was prepared in the same manner as in Example 1, except that TiO ₂ (B) was used as the negative electrode active material and a polyolefin porous separator having a porosity of 60% and a thickness of 10 μm made of polyethylene was used as the separator. Made.

(Example 14)
Except that TiO ₂ (B) is used as the negative electrode active material, a polyolefin porous separator with a porosity of 60% and a thickness of 10 μm made of polyethylene is used as the separator, and the number of turns of the separator on the outer peripheral portion is 20 times. A secondary battery was produced in the same manner as in Example 1.

(Example 15)
A secondary battery was produced in the same manner as in Example 1, except that graphite was used as the negative electrode active material and a polyolefin porous separator having a porosity of 60% and a thickness of 10 μm made of polyethylene was used as the separator.

(Example 16)
The same as Example 1 except that graphite is used as the negative electrode active material, a polyolefin porous separator having a porosity of 60% and a thickness of 10 μm made of polyethylene is used as the separator and the number of turns of the separator on the outer peripheral portion is 20 times A secondary battery was produced by the method of

(Example 17)
A secondary battery was produced in the same manner as in Example 1 except that LiMn ₂ O ₄ was used as the negative electrode active material.

(Example 18)
A secondary battery was produced in the same manner as in Example 1 except that LiMn ₂ O ₄ was used as the negative electrode active material, and the number of turns of the separator in the outer peripheral portion was set to 20.

(Example 19)
A secondary battery was produced in the same manner as in Example 1 except that the number of turns of the separator in the outer peripheral portion was set to 3 turns.

Example 20
A secondary battery was produced in the same manner as in Example 1 except that the electrode group was changed to a laminated electrode group.

(Example 21)
A secondary battery was produced in the same manner as in Example 20, except that the number of turns of the separator in the outer peripheral portion was set to 3 turns.

(Example 22)
A secondary battery was produced in the same manner as in Example 20 except that the number of turns of the separator in the outer peripheral portion was changed to 20.

(Example 23)
A secondary battery was produced in the same manner as in Example 20 except that the separator in the outer peripheral portion was not connected to the separator in the central portion. In addition, the separator of a center part and an outer peripheral part is the same.

(Example 24)
Using a porous polyolefin separator with a porosity of 50% and a thickness of 6 μm made of polyethylene in the central part, using a cellulose with a porosity of 60% and a thickness of 10 μm in the outer peripheral part, the separator in the outer peripheral part is connected to the separator in the central part A secondary battery was manufactured in the same manner as in Example 1 except that the number of turns of the separator in the outer peripheral portion was 10 times.

(Example 25)
A secondary battery is fabricated in the same manner as in Example 23, except that a mixture of aluminum oxide and methyl acrylate (porosity 40%) having a thickness of 6 μm and an average particle diameter of 1 μm is used for the central separator. did. The separator at the outer peripheral portion is the same as that of the first embodiment.

(Comparative example 1)
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that the number of turns of the separator in the outer peripheral portion was changed to 2 turns.

(Comparative example 2)
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that the number of turns of the separator in the outer peripheral portion was set to 50.

(Comparative example 3)
A secondary battery was produced in the same manner as in Example 1 except that the film thickness of the separator was 2 μm.

(Comparative example 4)
A secondary battery was produced in the same manner as in Example 1 except that the thickness of the separator was 25 μm.

(Comparative example 5)
A secondary battery was produced in the same manner as in Example 1 except that the porosity of the separator was 30%.

(Comparative example 6)
A secondary battery was produced in the same manner as in Example 1 except that the porosity of the separator was 95%, but the porosity of the separator was too high to be wound.

(Comparative example 7)
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that the number of turns of the separator in the outer peripheral portion was 0.

(Comparative example 8)
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 11 except that the number of turns of the separator in the outer peripheral portion was 0.

(Comparative example 9)
A secondary battery was produced in the same manner as in Example 13 except that the number of turns of the separator in the outer peripheral portion was changed to 2 turns.

(Comparative example 10)
A secondary battery was produced in the same manner as in Example 15, except that the number of turns of the separator in the outer peripheral portion was changed to 2 turns.

(Comparative example 11)
A secondary battery was produced in the same manner as in Example 20 except that the number of turns of the separator in the outer peripheral portion was changed to 2 turns.

(Comparative example 12)
A secondary battery was produced in the same manner as in Example 25 except that the number of turns of the separator in the outer peripheral portion was changed to 2 turns.

As compared with Comparative Example 1 in which the outermost separator is reduced, the example is shown to be superior in terms of the capacity retention rate after the cycle test and the resistance change rate. In addition, it is shown that the example is significantly superior in terms of volume energy density as compared with Comparative Example 2 in which a large number of separators are wound around the outermost periphery.
In the specification, some elements are represented only by elemental symbols.

While certain embodiments of the present invention have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the invention. These embodiments can be implemented in other various forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the invention described in the claims and the equivalents thereof as well as included in the scope and the gist of the invention.

100, 101, 102, 103, 104, 105: electrode group, 10: positive electrode, 11: positive electrode current collector, 12: positive electrode active material layer, 13: positive electrode current collection tab, 20: negative electrode, 21: negative electrode current collector , 22: negative electrode active material layer, 23: negative electrode current collecting tab, 30: first A separator, 40: first B separator, 50: second separator (second A separator), 60: identification code, 70: second B separator, 80 ... second separator, 90 ... second separator,
200 secondary battery 201 packaging material 202 electrode group 202 (100, 101, 102, 103) 203 positive electrode lead 204 negative electrode lead 205 lid 206 positive electrode terminal 207 negative electrode terminal 208: positive electrode backup lead 209: negative electrode backup lead 210: positive electrode insulating cover 211: negative electrode insulating cover 212: positive electrode gasket 213: negative electrode gasket 214: safety valve 215: electrolyte solution inlet 216: positive electrode current collector Tab 217, negative electrode current collecting tab and electrolyte 300 (not shown) battery module 301, cells 301, 302 positive electrode gasket 303 (303A, 303B) positive electrode terminal 304 safety valve 305 negative electrode gasket 306 (306) 306A, 306B) ... negative electrode terminal, 307 ... lower case, 308 ... upper case, 30 ... power output terminal (positive terminal), 310 ... power input terminal (negative terminal), 311 ... opening, 312 ... bus bar, 313 ... substrate, 314A ... positive terminal, 314B ... negative terminal, 315 ... lid,
400 ... storage device, 401 ... converter, 402 ... inverter, 403 ... external AC power supply, 404 ... load,
500 ... vehicle, 501 ... vehicle body, 502 ... motor, 503 ... wheel, 504 ... control unit,
600 ... projectile body, 601 ... body frame, 602 ... motor, 603 ... rotary wing, 604 ... control unit

Claims (18)

1. A central portion is an electrode group including a positive electrode, a negative electrode, a central portion in which a first separator disposed between the positive electrode and the negative electrode is wound, and an outer peripheral portion in which a second separator is wound around an outer periphery of the central portion. ,
   An electrode group in which the total number of turns of the second separator is 3 or more.
2. The porosity of the first separator is 40% to 90%,
   The electrode group according to claim 1, wherein a porosity of the second separator is 40% or more and 90% or less.
3. The thickness of the first separator is 4 μm or more and 20 μm or less,
   The electrode group according to claim 1, wherein a thickness of the second separator is 4 μm or more and 20 μm or less.
4. The electrode group according to any one of claims 1 to 3, wherein a total number of turns of the second separator is 40 or less.
5. The first separator and the second separator are in contact with each other,
   The electrode group according to any one of claims 1 to 4, wherein the second separator is wound around the central portion continuously from the outermost periphery.
6. The first separator and the second separator are continuous separators, or
   The electrode group according to any one of claims 1 to 5, wherein the first separator and the second separator are separated separators.
7. The porosity of the first separator is 60% to 80%,
   The electrode group according to any one of claims 1 to 6, wherein a porosity of the second separator is 60% or more and 80% or less.
8. The thickness of the first separator is 6 μm or more and 12 μm or less,
   The electrode group according to any one of claims 1 to 7, wherein a thickness of the second separator is 6 μm or more and 12 μm or less.
9. The electrode group according to any one of claims 1 to 8, wherein a total number of turns of the second separator is 30 or less.
10. The electrode group according to any one of claims 1 to 9, wherein a total number of turns of the second separator is 20 or less.
11. The electrode group according to any one of claims 1 to 10, wherein an identification code is written on the outermost periphery of the second separator.
12. The first separator is a non-woven fabric of cellulose,
    The electrode group according to any one of claims 1 to 12, wherein the second separator is a non-woven fabric of cellulose.
13. In an electrode group including a positive electrode, a negative electrode, a central portion on which a first separator disposed between the positive electrode and the negative electrode is wound, and an outer peripheral portion on which the second separator winds the central portion.
    An electrode group in which an identification code is written on the outermost periphery of the second separator.
14. A secondary battery comprising the electrode group according to any one of claims 1 to 13 and an electrolytic solution in a battery can.
15. A battery module using the secondary battery according to claim 14.
16. A storage device using the secondary battery according to claim 14 or the battery module according to claim 15.
17. A vehicle using the secondary battery according to claim 14 or the battery module according to claim 15.
18. A projectile using the secondary battery according to claim 14 or the battery module according to claim 15.
    
    

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