JP6125182B2 - Nonaqueous electrolyte secondary battery - Google Patents

Description

  Embodiments described herein relate generally to an electrode and a battery.

  The lithium ion secondary battery includes a positive electrode, a negative electrode, a separator, and an electrolytic solution. The separator is disposed between the positive electrode and the negative electrode, and the electrolytic solution is held in the separator. In an actual battery, in many cases, a positive electrode, a separator, and a negative electrode are stacked and wound to obtain a large electric capacity.

  The separator is used for the purpose of preventing the direct contact between the positive electrode and the negative electrode and holding the electrolytic solution. It is desirable that the thickness of the separator is small because the impedance can be reduced and the amount of electrolyte can be reduced. On the other hand, the thinner the separator, the lower the mechanical strength, and the separator breaks during manufacturing and actual use. Increases the risk of direct contact.

  Moreover, the electrode group generally used for the above-described battery is manufactured by winding the positive electrode, the first separator, the negative electrode, and the second separator while laminating them. At this time, it is desirable to increase the winding speed in order to increase the production efficiency, but if so, the mechanical load applied individually to the positive electrode, the first separator, the negative electrode, and the second separator increases. On the other hand, in order to obtain a large battery capacity, it is desirable to reduce the thickness of the metal foil (for example, aluminum foil) used for the current collector of the separator and each electrode, so that both production efficiency and battery capacity can be improved. Is difficult. In addition, the separator must be in an appropriate position between the two electrodes so that the positive electrode and the negative electrode are not in direct contact with each other, and since advanced position control is required during winding, the cost of the winding device can be reduced and the winding can be performed. It is an obstacle to speed improvement.

Japanese Patent Laid-Open No. 10-50348 JP 2003-59486 A JP 2008-103310 A

  The problem to be solved by the present invention is to provide an electrode and a battery that are safe and have high production efficiency.

According to the embodiment, a non-aqueous electrolyte secondary battery including a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolytic solution is provided. The positive electrode includes a positive electrode current collector, a positive electrode active material-containing layer formed on the positive electrode current collector, and a positive electrode current collector tab electrically connected to the positive electrode current collector. The negative electrode includes a negative electrode current collector, a negative electrode active material-containing layer formed on the negative electrode current collector, and a negative electrode current collector tab electrically connected to the negative electrode current collector. Separator, a part of the surface of the surface and the positive electrode current collector tabs of the positive electrode active material-containing layer, an insulating material dispersed attached to a plurality of locations, the surface及beauty anode current collector tabs of the negative electrode active material-containing layer It consists of an insulating substance dispersed and attached to a part of the surface at a plurality of locations. Part of the positive insulating material and part of the negative insulating material overlap each other so as to intersect. The insulating materials for the positive electrode and the negative electrode are made of a material that is insoluble in the electrolyte.

Sectional drawing which shows the electrode which concerns on embodiment. The expanded sectional view of the A section of FIG. Sectional drawing which shows the electrode group used for the battery which concerns on embodiment. The top view which shows the electrode which concerns on embodiment. The top view which shows the electrode which concerns on embodiment. The top view which shows the state which contacted the insulating substance of the one pole, and the insulating substance of the other pole. The partial notch perspective view of the battery which concerns on embodiment.

  Hereinafter, embodiments will be described with reference to the drawings. According to the embodiment, an electrode including a current collector, an active material-containing layer, a current collecting tab, and an insulating material (a material having no electrical conductivity) is provided. The active material-containing layer is formed on one side or both sides of the current collector. The current collecting tab is electrically connected to the current collector. The insulating material is attached to part of the surfaces of the active material-containing layer and the current collecting tab.

  Since the insulating substance functions as a separator, the separator as a single component can be omitted by providing the electrode with a separator function. Moreover, since the mechanical strength is increased by attaching a substance corresponding to the separator to the electrode, it is difficult to cut the electrode when winding the electrode, and it is possible to increase the winding speed or reduce the thickness of the current collector of the electrode. . In addition, since the separator adheres to the electrode and always follows, the positional relationship between the electrode and the separator does not change during winding, and it is possible to reduce the misalignment during winding. Furthermore, since the surface of the active material-containing layer and the separator are integrated, the separator is not cut off at the time of winding, and the positive electrode and the negative electrode are not contacted in the electrode group, so that the safety of the battery can be improved.

  The insulating material is preferably insoluble in the electrolytic solution, and specific examples include cellulose, polyethylene, polypropylene, and the like. Polypropylene and polyethylene are desirable because they are easily processed into a spherical or fibrous shape and are insoluble in the electrolyte. A thermoplastic resin and a thermosetting resin can also be used. By using a thermoplastic resin and / or a thermosetting resin, the insulating material can be attached by heating and melting. The type of insulating material used can be one type or two or more types.

  The insulating substance can be in the form of simple particles, composite particles, aggregates of these particles, and the like. The shape of the particles may be only one type or a combination of multiple types.

  The shape of the insulating material particles is not particularly limited, but it is desirable that the contact area with the active material be as small as possible so as not to hinder the movement of charges due to charge and discharge. At the same time, in order to prevent contact between the positive electrode and the negative electrode, and to prevent the occurrence of exfoliating parts that cannot follow the electrode that expands and contracts during winding, the insulating material should have multiple points attached to the electrode. Is desirable. Considering these, for example, a spherical shape, a cylindrical shape, and a fibrous shape can be mentioned. The particle shape can be one type or two or more types.

  The length of the insulating material is preferably 0.001 μm or more and 1 mm or less. By setting the length to 0.001 μm or more, the possibility of contact between the positive electrode and the negative electrode can be further reduced. Moreover, resistance can be made small by making length into 1 mm or less. A more preferable range of the length is a range of 2 μm or more and 50 μm or less.

  The width in the short side direction of the insulating material is preferably 0.001 μm or more and 1 mm or less. By setting the width in the short side direction to 0.001 μm or more, the possibility of contact between the positive electrode and the negative electrode can be further reduced. Further, the resistance can be reduced by setting the width in the short side direction to 1 mm or less. A more preferable range of the width in the short side direction is a range of 2 μm or more and 50 μm or less.

  The width in the long side direction of the insulating material is preferably 0.001 μm or more and 1000 mm or less. By setting the width in the long side direction to 0.001 μm or more, the possibility of contact between the positive electrode and the negative electrode can be further reduced. Moreover, resistance can be made small by making the width | variety of a long side direction into 1000 mm or less. A more preferable range of the width in the long side direction is a range of 2 μm or more and 50 μm or less.

  The insulating material is a spherical particle having a diameter of 0.001 μm to 1 mm, a fibrous particle having a diameter of 0.001 μm to 1 mm and a length of 0.001 μm to 1000 mm, or a mixture of the spherical particle and the fibrous particle. It is desirable that This can further reduce the resistance and the possibility of contact between the positive electrode and the negative electrode.

  As the method for attaching the insulating material, spraying, electrostatic coating, printing, or transfer, in which the insulating material is applied to the active material surface or the current collecting tab surface together with the binder, can be used. Examples of the method include a method of heating and welding the material surface or the current collecting tab surface after being positioned by means of coating, printing, spraying, or the like, and any of them may be used. Examples of printing include inkjet, gravure printing, offset printing, and screen printing. Thermal welding is a method of adhering to the electrode using the melting point of the insulating material. Examples of the binder include a material that does not dissolve in an electrolytic solution such as PVDF. Among these, ink jet, gravure printing, offset printing, screen printing, and transfer are preferable because they are suitable for arranging insulating substances in arbitrary positions and directions. According to gravure printing, the manufacturing cost can be kept low.

  Regarding the amount of the insulating material, the electrode active material is exposed even after the insulating material is adhered, and sufficient battery characteristics are exhibited by sufficiently contacting the electrolytic solution, and the positive electrode and the negative electrode are stacked and wound. It is desirable to prevent the positive electrode and the negative electrode from coming into contact with each other.

  The range to which the insulating substance is attached can be one or both sides of the positive and negative electrodes. In the case of one side, it is desirable to include a portion that may come into contact with the counterpart electrode. When the adhesion amount is sufficient, the insulating material may be adhered to only one of the electrodes.

  It is desirable that the insulating material is scattered (dispersed in a plurality of locations) and attached to part of the surface of the active material-containing layer and the current collecting tab. By exposing the surface of the active material-containing layer, a sufficient contact area between the active material and the electrolytic solution can be ensured, and ion diffusion between the electrodes can be made smooth. Further, when the electrode is wound, the insulating substance attached to the surface may peel off without being able to maintain the attached state due to the attached portion receiving the expansion and contraction force. At this time, even when some of the adhering parts are peeled off due to the insulating material adhering to the electrode surface at a plurality of places, the insulating material as a whole can maintain the adhering state to the electrode surface.

  The insulating material may be randomly arranged on a part of the surface of the active material containing layer and the current collecting tab or may be arranged with regularity. The direction of the arrangement of the insulating material can be selected from any of the width direction, the length direction, and the other direction of the electrode. In order to increase the active material to which the insulating material is not adhered by increasing the interval between the insulating materials, it is desirable that the insulating materials are arranged so that they intersect when the positive electrode and the negative electrode face each other. Furthermore, if the insulating material is arranged at an angle close to the width direction of the electrode (substantially parallel to the width direction), when the electrode is wound and the electrolyte is permeated into the wound electrode, the electrolyte permeates. It is more desirable because it does not disturb.

  It is desirable that the gap be such that the positive electrode and the negative electrode are not in direct contact even if the electrode is distorted or deformed by winding.

  Also, since the insulating substance unit particles do not adhere to each other or adhere to each other with an intensity lower than the adhesion strength to the electrode surface, the insulating substance follows the electrode even when the electrode breaks. Thus, it is possible to maintain the insulation of the electrode.

  The electrode of the embodiment will be described with reference to FIGS. 1 and 2. As shown in FIG. 1, the electrode 1 includes a sheet-shaped current collector 2, an active material-containing layer 3, a strip-shaped current collecting tab 4, and an insulating material 5. The active material-containing layer 3 is formed on both surfaces of the current collector 2. The current collecting tab 4 is electrically connected to the current collector 2 by being formed of a portion of the current collector 2 where the active material containing layer 3 is not formed. The insulating material 5 is attached to part of the surfaces of the active material-containing layer 3 and the current collecting tab 4. As shown in FIG. 2, the insulating material 5 is a composite particle having insulating material particles 5a and a binder 5b partially bonded to the surface of the insulating material particles 5a. The insulating material particles 5a are bonded to the surface of the active material containing layer 3 (or the current collecting tab 4) by the binder 5b. Some of the composite particles are attached to the surface alone, and some of the other particles are aggregated.

  When the electrode 1 shown in FIG. 1 is used as one electrode 1 and the other electrode 6 and the insulating material 5 of the one electrode 1 and the insulating material 5 of the other electrode 6 are brought into contact with each other as shown in FIG. And the other electrode 6 can be insulated by the insulating material 5, and the insulating material 5 can function as a separator. The insulating material 5 may be formed only on one of the one electrode 1 and the other electrode 6.

  The electrode and battery of an Example are demonstrated below.

  A polypropylene fiber having a fiber diameter of 10 μm and a fiber length of 50 μm is attached to the surfaces of the positive electrode and the negative electrode of the lithium ion secondary battery via PVDF. The range to be adhered is the current collecting tab surface over the entire surface of the active material containing layer of each of the positive and negative electrodes and the subsequent width of 3 mm. Thereby, even if it laminates | stacks a positive electrode and a negative electrode and winds these at high speed, the insulation between positive and negative electrodes can be maintained.

  As shown in FIG. 4, on the surface of the positive electrode 7, the polypropylene fibers 8 are arranged at an angle θ with respect to the width direction (direction parallel to the winding axis) X of the positive electrode 7. On the other hand, as shown in FIG. 5, on the surface of the negative electrode 9, the polypropylene fibers 8 are arranged with an angle θ inclined with respect to the width direction (direction parallel to the winding axis) X of the negative electrode 9. The polypropylene fiber 8 of the negative electrode 9 is inclined in the opposite direction to the positive electrode 7. The arrangement of the polypropylene fibers 8 can be performed by gravure printing, for example. When the positive electrode 7 and the negative electrode 9 are overlapped, as shown in FIG. 6, the polypropylene fiber 8 of the positive electrode 7 and the polypropylene fiber 8 of the negative electrode 9 intersect and come into contact with each other, thereby further increasing the certainty of insulation between the positive and negative electrodes. Can do. The angle θ may be the same or different between the positive and negative electrodes, but is preferably in the range of 0 ° to 45 ° (0 ° is a case where the positive electrode 7 or the negative electrode 9 is arranged in parallel with the width direction X). . Thereby, the permeability of the electrolyte solution to the positive and negative electrodes can be ensured.

  The length, width (long side direction and short side direction), interval, angle, etc. of the insulating material are values measured by observation with a transmission electron microscope (TEM), a scanning electron microscope (SEM), an optical microscope, etc. The average value is used.

  An example of the nonaqueous electrolyte battery is shown in FIG. In the prismatic nonaqueous electrolyte battery shown in FIG. 7, the wound electrode group 13 is housed in a metal bottomed rectangular cylindrical container (exterior member) 11. The wound electrode group 13 is formed, for example, by winding a laminate in the order of a negative electrode, a separator, a positive electrode, and a separator in a spiral shape and press molding.

  The negative electrode tab 18 has one end electrically connected to the negative electrode current collector and the other end electrically connected to the negative electrode terminal 20. The negative terminal 20 is fixed to the rectangular lid 12 via a negative gasket 21. One end of the positive electrode tab 17 is electrically connected to the positive electrode current collector, and the other end is electrically connected to the positive electrode terminal 19 fixed to the rectangular lid 12. The positive electrode tab 17 and the negative electrode tab 18 are preferably made of the same material as the positive and negative electrode current collectors, respectively, in order to reduce the contact resistance with the positive and negative electrode current collectors.

  The nonaqueous electrolytic solution is injected from, for example, an opening of the container 11 and accommodated in the container 11. The wound electrode group 13 and the non-aqueous electrolyte are sealed in the container 11 by welding the rectangular lid 12 to the opening of the container 11.

  In FIG. 7, a metal container is used as the container for housing the electrode group, but a laminate film container can be used instead of the metal container. In FIG. 7, a wound electrode group is used. However, a stacked electrode group in which positive electrodes and negative electrodes are alternately stacked via separators may be used.

  Hereinafter, the positive electrode, the negative electrode, and the non-aqueous electrolyte will be described.

  The positive electrode is produced, for example, by applying a slurry containing a positive electrode active material to a current collector made of an aluminum foil or an aluminum alloy foil, drying, and cutting and pressing as necessary. Although it does not specifically limit as a positive electrode active material, The oxide, sulfide, polymer, etc. which can occlude / release lithium can be used. Preferable active materials include lithium manganese composite oxide, lithium nickel composite oxide, lithium cobalt composite oxide, lithium iron phosphate, and the like that can obtain a high positive electrode potential. The negative electrode is produced by applying a slurry containing a negative electrode active material to a current collector made of an aluminum foil or an aluminum alloy foil, drying, and cutting and pressing as necessary. The negative electrode active material is not particularly limited, and metal oxides, metal sulfides, metal nitrides, alloys, and the like that can occlude and release lithium can be used. Preferably, the lithium ion occlusion and release potential is metal lithium. It is a substance that becomes noble 0.4V or more with respect to the potential. Since the negative electrode active material having such a lithium ion storage / release potential can suppress the alloy reaction between aluminum or an aluminum alloy and lithium, it is possible to use aluminum or an aluminum alloy for a negative electrode current collector and a negative electrode related component. And For example, there are titanium oxide, lithium titanium oxide, tungsten oxide, amorphous tin oxide, tin silicon oxide, silicon oxide, etc. Among them, lithium titanium composite oxide is preferable.

As the non-aqueous electrolyte, a non-aqueous electrolyte prepared by dissolving an electrolyte (for example, a lithium salt) in a non-aqueous solvent is used. Examples of the non-aqueous solvent include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), γ-butyrolactone (γ -BL), sulfolane, acetonitrile, 1,2-dimethoxyethane, 1,3-dimethoxypropane, dimethyl ether, tetrahydrofuran (THF), 2-methyltetrahydrofuran and the like. Nonaqueous solvents may be used alone or in combination of two or more. Examples of the electrolyte include lithium perchlorate (LiClO ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium arsenic hexafluoride (LiAsF ₆ ), and trifluorometa. A lithium salt such as lithium sulfonate (LiCF ₃ SO ₃ ) can be given. The electrolyte may be used alone or in combination of two or more. The amount of electrolyte dissolved in the non-aqueous solvent is desirably 0.2 mol / L to 3 mol / L.

  According to the electrodes of these embodiments, since the insulating material attached to a part of the surface of the active material containing layer and the current collecting tab is included, a safe and highly efficient electrode can be provided.

Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.
Hereinafter, the invention described in the scope of claims of the present application will be appended.
[1]
A current collector,
An active material-containing layer formed on the current collector;
A current collecting tab electrically connected to the current collector;
An insulating material attached to a part of the surface of the active material-containing layer and the current collecting tab;
An electrode comprising:
[2]
The electrode according to [1], wherein the insulating material is scattered and attached to part of the surfaces of the active material-containing layer and the current collecting tab.
[3]
The electrode according to [1], wherein the insulating material is regularly attached to part of the surfaces of the active material-containing layer and the current collecting tab.
[4]
The electrode according to [2] or [3], wherein the insulating substance is a thermoplastic resin or a thermosetting resin.
[5]
The electrode according to [2] or [3], wherein the insulating substance is attached by binder, coating, spraying, electrostatic coating, inkjet, gravure printing, offset printing, screen printing or transfer. .
[6]
The insulating substance is a spherical particle having a diameter of 0.001 μm to 1 mm, or a fibrous particle having a diameter of 0.001 μm to 1 mm and a length of 0.001 μm to 1000 mm, or the spherical particle and the fibrous particle. The electrode according to [2] or [3], which is a mixture of
[7]
The insulating material is attached to a part of the surface of the active material-containing layer and the current collecting tab in the form of a single particle or an aggregate of a plurality of particles [2] or [ 3] The electrode according to the above.
[8]
A battery comprising the electrode according to any one of [1] to [7] as at least one of a positive electrode and a negative electrode.
[9]
The electrode according to any one of [1] to [7] is used for the positive electrode and the negative electrode, and the positive electrode and the negative electrode are arranged so that the insulating substance of the positive electrode and the insulating substance of the negative electrode are in contact with each other. The battery according to [8], which is laminated.

  DESCRIPTION OF SYMBOLS 1,6 ... Electrode, 2 ... Current collector, 3 ... Active material containing layer, 4 ... Current collection tab, 5 ... Insulating material, 5a ... Insulating material particle, 5b ... Binder, 7 ... Positive electrode, 8 ... Polypropylene fiber , 9 ... negative electrode, 11 ... container, 13 ... electrode group, 17 ... positive electrode tab, 18 ... negative electrode tab, 19 ... positive electrode terminal, 20 ... negative electrode terminal, 21 ... negative electrode gasket.

Claims (6)

A positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte solution ,
The positive electrode includes a positive electrode current collector, a positive electrode active material-containing layer formed on the positive electrode current collector, and a positive electrode current collector tab electrically connected to the positive electrode current collector,
The negative electrode includes a negative electrode current collector, a negative electrode active material-containing layer formed on the negative electrode current collector, and a negative electrode current collector tab electrically connected to the negative electrode current collector,
The separator includes an insulating material dispersed and attached to a part of the surface of the positive electrode active material-containing layer and the surface of the positive electrode current collecting tab, and the surface of the negative electrode active material-containing layer and the negative electrode collector. A part of the surface of the electric tab consists of an insulating material dispersed and attached to multiple locations,
A part of the insulating material of the positive electrode and a part of the insulating material of the negative electrode overlap so as to intersect ,
The insulating material for the positive electrode and the negative electrode is a non-aqueous electrolyte secondary battery made of a material insoluble in the electrolytic solution . Wherein at least one of the positive and negative electrodes of the insulating material is adhered with regularity to a portion of the positive electrode active material-containing layer or the anode active material-containing layer and the positive electrode current collector tab or the negative electrode current collector tab surface non-aqueous electrolyte secondary battery of 請 Motomeko 1, wherein that. At least one of the heat Ru thermoplastic resin or thermosetting resin der 請 Motomeko 1 or 2 non-aqueous electrolyte secondary battery according insulating material of the positive electrode and the negative electrode. Wherein at least one of adhesion of the positive electrode and the negative electrode of the insulating material, binder, coating, spraying, electrostatic coating, inkjet, gravure printing, offset printing, Ru der by screen printing or transfer 請 Motomeko 1 to 3 The nonaqueous electrolyte secondary battery according to any one of the above. At least one of the positive and negative electrode insulating materials is a spherical particle having a diameter of 0.001 μm to 1 mm, or a fibrous particle having a diameter of 0.001 μm to 1 mm and a length of 0.001 μm to 1000 mm, or non-aqueous electrolyte secondary battery according to any one of mixtures der Ru請 Motomeko 1 to 4 of the spherical particles and the fibrous particles. 5. The non-aqueous electrolyte secondary battery according to claim 1, wherein at least one of the positive and negative electrode insulating materials is in the form of a single particle or an aggregate of a plurality of particles.

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