JP2019125485A - Nonaqueous electrolyte secondary battery, and method for manufacturing the same - Google Patents

Abstract

To provide: a nonaqueous electrolyte secondary battery improved in the achievement of the rise in capacity, repeated usability and rapid charging capability by putting a separator between electrodes having an uneven structure without being wrinkled or broken; and a method for manufacturing the nonaqueous electrolyte secondary battery.SOLUTION: According to the inventors, a nonaqueous electrolyte secondary battery has a laminate structure arranged by laminating a positive electrode layer having an uneven structure, a separator and a negative electrode layer having an uneven structure in this order. The proportion of a length of the profile line of the uneven structure of the positive or negative electrode layer and a length of the profile line of the separator opposed to the positive or negative electrode layer when a section of the above-described laminate structure is observed, is limited within a given range.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a non-aqueous electrolyte secondary battery and a method of manufacturing the non-aqueous electrolyte secondary battery.

  Non-aqueous electrolyte secondary batteries such as lithium ion secondary batteries can be widely used mainly for information communication devices such as mobile phones, tablet type information terminals, notebook personal computers, etc. because they can exhibit high output performance even if they are small and light. It is done.

  Such a non-aqueous electrolyte secondary battery is expected to further increase its output power as it is used as a power source in electric vehicles, hybrid vehicles and the like. A non-aqueous electrolyte secondary battery capable of achieving high output includes a positive electrode, a negative electrode, and a separator sandwiched between the positive electrode and the negative electrode, and at least one of the positive electrode and the negative electrode has a height difference of 5 μm to 100 μm. A lithium secondary battery having a concavo-convex structure of the following has been proposed (see Patent Document 1).

JP 2008-010253 A

However, the lithium secondary battery described in Patent Document 1 is manufactured by sandwiching a separator between electrodes having a concavo-convex structure. In this case, the separator may be broken due to the sliding between the projections, or wrinkles may occur when the separator is sandwiched between the electrodes.
There is a concern that such separator breakage or separator wrinkles may reduce the life of the lithium secondary battery during long-term use. For this reason, the lithium secondary battery described in Patent Document 1 has room for improvement in capacity, repeatability, and high-speed charge performance.

  The present invention has been made in view of the above-mentioned problems, and has a non-folded structure in which high capacity, repeated use and high-speed charging performance are improved by sandwiching a separator without wrinkles or breakage between electrodes having a concavo-convex structure. An object of the present invention is to provide a water electrolyte secondary battery and a method of manufacturing the non-aqueous electrolyte secondary battery.

  The inventors of the present invention, in a non-aqueous electrolyte secondary battery having a laminated structure in which a positive electrode layer having a concavo-convex structure, a separator, and a negative electrode layer having a concavo-convex structure are laminated in this order, By limiting the ratio of the length of the outline of the concavo-convex structure of the positive electrode layer or the negative electrode layer to the length of the outline of the separator facing the positive electrode layer or the negative electrode layer within the predetermined range, It has been found that the problems can be solved, and the present invention has been completed. Specifically, the present invention provides the following.

A first aspect of the present invention is a non-aqueous electrolyte secondary battery having a laminated structure in which a positive electrode layer, a separator, and a negative electrode layer are laminated in this order,
The positive electrode layer has a plurality of first protrusions projecting in the separator direction from the positive electrode surface,
The negative electrode layer has a plurality of second protrusions protruding from the negative electrode surface in the separator direction,
The positive electrode layer and the negative electrode layer are stacked such that the first protrusion is located in the space between the adjacent second protrusions, and the second protrusion is located in the space between the adjacent first protrusions,
When observing the cross section of the laminated structure including the positive electrode layer, the negative electrode layer, and the separator, the total length of the outline A1 of the surface of the separator facing the positive electrode surface in the cross section is L1 and defined by the plurality of first protrusions. The ratio L2 / L1 is 0.95 or more and 1.05 or less, where L2 is the total length of the contour line B1 of the uneven structure to be made,
When the total length of the outline A2 of the surface of the separator facing the negative electrode surface in the cross section is L3, and the total length of the outline B2 of the concavo-convex structure defined by the plurality of second protrusions is L4, the ratio L4 / L3 is And 0.95 or more and 1.05 or less.

A second aspect of the present invention is a method for producing the non-aqueous electrolyte secondary battery according to the first aspect,
A step of forming a positive electrode layer or a negative electrode layer on the first current collector layer, wherein a plurality of first protrusions are provided on the positive electrode surface to form a positive electrode layer, or a plurality of second protrusions are formed on the negative electrode surface. Forming a negative electrode layer by
Applying a coating solution for forming a separator containing a dispersion medium on the positive electrode layer or the negative electrode layer to form a coated film, and then removing the dispersion medium from the coated film to form a separator;
A paste for forming a positive electrode or for forming a negative electrode is coated on the separator, and the first current collection is performed such that the positive electrode layer or the negative electrode layer on the first current collector layer is opposed via the separator. Forming a positive electrode layer or a negative electrode layer which is opposite to the layer formed on the body layer;
A method of manufacturing a non-aqueous electrolyte secondary battery, comprising the steps of: forming a second current collector layer on a positive electrode layer or a negative electrode layer, wherein the layer is formed on the first current collector layer at the counter electrode. It is.

  According to the present invention, it is possible to provide a non-aqueous electrolyte secondary battery with improved capacity, repeated use and high-speed charge performance, and a method of manufacturing the non-aqueous electrolyte secondary battery.

It is a figure which shows typically the cross section of the laminated structure containing a positive electrode layer, a separator, and a negative electrode layer. It is a figure which shows the outline of the manufacturing method of a non-aqueous electrolyte secondary battery.

«Non-aqueous electrolyte secondary battery»
Hereinafter, the configuration of the non-aqueous electrolyte secondary battery will be described with reference to FIG. FIG. 1 is a view showing a schematic configuration of a cross section perpendicular to a plane direction of a laminated structure in a non-aqueous electrolyte secondary battery. The structure of the non-aqueous electrolyte is not limited to the structure shown in FIG. 1 as long as the predetermined requirements described above are satisfied.
In addition, about the specification of this application, it may only be described as a "battery" about a non-aqueous electrolyte secondary battery.

A non-aqueous electrolyte secondary battery (battery) has a laminated structure in which a positive electrode layer 11, a separator 10, and a negative electrode layer 12 are stacked in this order, as shown in FIG.
The surface of the positive electrode layer 11, the surface of the negative electrode layer 12, between the positive electrode layer 11 and the separator 10, and between the negative electrode layer 12 and the separator 10 are You may have various functional layers which may be provided between an electrode and a separator in a water-electrolyte secondary battery.

  The positive electrode layer 11 and the negative electrode layer 12 are usually provided in contact with the current collector layer 13.

The positive electrode layer 11 has a plurality of first protrusions 11 b that project in the direction of the separator 10 (the separator direction) from the positive electrode surface 11 a.
The negative electrode layer 12 has a plurality of second protrusions 12 b protruding from the negative electrode surface 12 a in the separator direction.
Here, the positive electrode surface 11a or the negative electrode surface 12a is a surface that faces the surface of the separator 10 and supports the plurality of first protrusions 11a or the plurality of second protrusions 12b.

The heights of the plurality of first protrusions 11 b and the plurality of second protrusions 12 b may be uniform or nonuniform, and are preferably uniform.
The protrusion height of each first protrusion 11 b from the positive electrode surface 11 a and the protrusion height of each second protrusion 12 b from the negative electrode surface 12 a are each preferably 3 μm or more, more preferably 5 μm or more, and particularly preferably 20 μm or more.
The upper limit value of the height of the first protrusions 11b from the positive electrode surface 11a and the height of the protrusions of the second protrusions 12b from the negative electrode surface 12a is not particularly limited, but is, for example, 500 μm or less.
In addition, protrusion height is protrusion height of the orthogonal | vertical direction with respect to the positive electrode surface 11a or the negative electrode surface 12a.

The average of the projection heights of the plurality of first projections 11b from the positive electrode surface 11a and the average of the projection heights of the plurality of second projections 12b from the negative electrode surface 12a are preferably 5 μm or more, and more preferably 20 μm or more. 50 μm or more is particularly preferable, and may be more than 100 μm.
The average of the projection heights of the plurality of first projections 11 b from the positive electrode surface 11 a and the average of the projection heights of the plurality of second projections 12 b from the negative electrode surface 12 a are not particularly limited. Each is 500 μm or less.

  In the positive electrode layer 11 and the negative electrode layer 12, the first protrusions 11b are located in the space between the adjacent second protrusions 12b, and the second protrusions 12b are located in the space between the adjacent first protrusions 11b. To be stacked. That is, the positive electrode layer 11 and the negative electrode layer 12 are stacked such that the plurality of first protrusions 11 b and the plurality of second protrusions 12 b are engaged with each other through the separator 10.

The shapes of the first protrusions 11 b and the second protrusions 12 b are not particularly limited as long as a desired laminated structure can be formed.
The shape of the first protrusion 11 b and the second protrusion 12 b is, for example, a pillar such as a square pole, a hexagonal pole, or a cylinder; a square frustum, a frustum shape of a hexagonal frustum, a frustum sugar; A linear shape having a trapezoidal cross section, and the like.
The tops of the first protrusion 11 b and the second protrusion 12 b may be rounded.

  Since it is easy to obtain a battery excellent in high-speed charge performance, the angle (taper angle) formed by the side surface of the first protrusion 11 b and the second protrusion 12 b with the positive electrode surface 11 a or the negative electrode surface 12 a is 50 ° to 90 °. Or less is preferable, 60 ° or more and 90 ° C. or less is more preferable, and 70 ° or more and 90 ° or less is particularly preferable.

The arrangement of the plurality of first protrusions 11 b or the plurality of second protrusions on the positive electrode surface 11 a or the negative electrode surface 12 a is laminated such that the positive electrode layer 11, the negative electrode layer 12, and the separator 10 satisfy predetermined requirements. It is not particularly limited as long as it is done.
For example, when the first protrusion 11a and the second protrusion 12a have a columnar or frustum shape, the first protrusion 11a or the second protrusion 12a is generally checkered on the positive electrode surface 11a or the negative electrode surface 12a. Preferably, they are arranged in a pattern.
In addition, when the shapes of the first protrusion 11a and the second protrusion 12a are linear, the plurality of linear first protrusions 11b have approximately the same width as the linear second protrusions 12b on the positive electrode surface 11a. Preferably, they are spaced and parallel. The plurality of linear first protrusions 12 b are preferably arranged in parallel on the negative electrode surface 12 a with an interval substantially equal to the width of the linear first protrusions 11 b.

When the cross section of the laminated structure including the positive electrode layer 11, the negative electrode layer 12, and the separator 10 is observed, the total length of the outline A1 of the surface of the separator 10 facing the positive electrode surface 11a in the cross section is L1. Ratio L2 / L1 is 0.95 or more and 1.05 or less, and 0.97 or more and 1.03 or less is more than the total length of the outline B1 of the concavo-convex structure defined by the first protrusion of Preferably, 0.98 or more and 1.00 or less is particularly preferable.
In the case where the total length of the outline A2 of the surface of the separator 10 facing the negative electrode surface 12a in the above cross section is L3, and the total length of the outline B2 of the concavo-convex structure defined by the plurality of second protrusions is L4. The ratio L4 / L3 is 0.95 or more and 1.05 or less, more preferably 0.97 or more and 1.03 or less, and particularly preferably 0.98 or more and 1.00 or less.

  In FIG. 1, since the separator 10 is provided in close contact with the positive electrode layer 11 and the negative electrode layer 12, the outline A1 and the outline B1 are substantially the same line, and The outline A2 and the outline B2 are substantially the same line.

That the ratio L2 / L1 and the ratio L4 / L3 are within the above-described predetermined range means that the outline of the separator 10 substantially matches both the outline of the positive electrode layer 11 and the outline of the negative electrode layer 12 Do.
That is, the positive electrode layer 11, the negative electrode layer 12, and the separator 10 are stacked in a state in which the positive electrode layer 11 and the negative electrode layer 12 are provided in such a manner that there is substantially only a space for the separator therebetween. . In this case, since the filling rate (ratio of the volume) of the positive electrode layer 11, the negative electrode layer 12, and the separator 10 per unit volume is high, the capacity of the battery can be increased.
For example, as in the technique described in Patent Document 1, when laminating a positive electrode having a concavo-convex structure that has already been produced and a negative electrode having a concavo-convex structure via a separator, the groove of this concavo-convex structure has a separator A gap with the electrode is created. In this case, it is difficult to set desired values for the aforementioned values of L2 / L1 and L4 / L3.

  In addition, when the ratio L2 / L1 and the ratio L4 / L3 are within the above-described predetermined range, the distance between the surface of the positive electrode layer 11 and the surface of the negative electrode layer 12 is approximately the thickness of the separator 10 at any place. And uniform. Therefore, the battery life can be extended and the high-speed charging performance can be improved by uniformizing the charge and discharge reaction.

In a cross section of a laminated structure including the positive electrode layer 11, the negative electrode layer 12, and the separator 10, the width of the first protrusion 11a at the positive electrode surface 11b and the width of the second protrusion 12a at the negative electrode surface 12b. And 100 μm or less are preferable, 50 μm or less is more preferable, and 10 μm or less is particularly preferable. By setting such a range, a battery with higher capacity can be realized.
Further, from the viewpoint of the processability of the electrode, the lower limit value of the width at the position of the positive electrode surface 11b of the first protrusion 11a and the width at the position of the negative electrode surface 12b of the second protrusion 12a is 5 μm or more. is there.

  The above cross section includes the center of gravity of the main surface of the laminated structure, which is determined when the laminated structure is observed from a direction perpendicular to the surface direction of the laminated structure, and is defined by the plurality of first protrusions. A cross section in which the sum of the total length L2 of the outline B1 of the concavo-convex structure and the total length L4 of the outline B2 of the concavo-convex structure defined by the plurality of second protrusions is maximum is selected.

  Hereinafter, each configuration of the battery will be described in order.

<Positive electrode layer>
As a material of the positive electrode layer 11 in a battery, various materials applied to the positive electrode of various well-known non-aqueous electrolyte secondary batteries can be used.
The material of the positive electrode layer 11 typically contains a positive electrode active material, a conductive material, and a binder.
The method of forming the positive electrode layer 11 will be described later with respect to a method of manufacturing a battery.

As the positive electrode active material, a known positive electrode active material can be used without particular limitation. When the battery is a lithium ion secondary battery, an inorganic material capable of inserting or extracting lithium ions is used as a positive electrode active material.
More specifically, transition with lithium such as lithium cobalt complex oxide, lithium nickel complex oxide, lithium manganese complex oxide, lithium manganese nickel complex oxide, lithium nickel cobalt manganese complex oxide, lithium iron phosphorus complex oxide, etc. Complex oxides with metals can be mentioned.

The conductive material is not particularly limited as long as it is an electron conductive material that does not adversely affect the performance of the positive electrode battery. For example, graphite such as natural graphite (scaly graphite, flake graphite) or artificial graphite, acetylene black, carbon black, ketjen black, carbon whisker, needle coke, carbon fiber, metal (copper, nickel, aluminum, silver, gold, etc.) And mixtures of two or more thereof can be used.
Among these, as the conductive material, carbon black and acetylene black are preferable because they are excellent in electron conductivity and easy to form the positive electrode layer 11 using a paste.

The binder is a positive electrode active material, a conductive material, and a matrix material for holding. Examples of the binder include fluorine-containing resins such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF) and fluororubber; thermoplastic resins such as polypropylene and polyethylene: ethylene propylene diene monomer (EPDM) rubber, sulfone It is possible to use rubber materials such as hydrogenated EPDM rubber and natural butyl rubber (NBR) alone or in combination of two or more.
In addition, an aqueous dispersion of cellulose or styrene butadiene rubber (SBR) can be used as a binder.

As described later, as the positive electrode layer 11, it is preferable to use a paste containing a positive electrode active material, a conductive material, and a binder. In this case, the paste for forming the positive electrode usually contains a solvent or a dispersion medium.
As the solvent or dispersion medium, for example, N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, methyl ethyl ketone, cyclohexanone, methyl acetate, methyl acrylate, diethylenetriamine, N, N-dimethylamino Organic solvents such as propylamine, ethylene oxide and tetrahydrofuran can be preferably used.

  In addition, a dispersant, a thickener and the like may be added to water, and the active material and the conductive material may be slurried with a latex such as SBR. As a thickener, polysaccharides, such as carboxymethylcellulose and methylcellulose, can be used individually or in combination of 2 or more types, for example.

<Negative electrode>
As a material of the positive electrode layer 12 in the battery, various materials applied to the negative electrode of various known non-aqueous electrolyte secondary batteries can be used.
The material of the negative electrode layer 12 typically contains a negative electrode active material, a conductive material, and a binder.
The method for forming the negative electrode layer 12 will be described later for the method for manufacturing a battery.

As the negative electrode active material, known negative electrode active materials can be used without particular limitation. When the battery is a lithium ion secondary battery, examples of the negative electrode active material include lithium, an inorganic compound such as a lithium alloy and a tin compound, a carbonaceous material capable of absorbing and releasing lithium ions, and a conductive polymer. Among these, carbonaceous materials are preferable in terms of safety.
The carbonaceous material is not particularly limited, and cokes, glassy carbons, graphites, non-graphitizable carbons, pyrolytic carbons, carbon fibers and the like can be mentioned. Among these, graphites such as artificial graphite and natural graphite have an operating potential close to that of metal lithium, and can be charged and discharged at high operating voltage, and when self-discharge is suppressed when lithium salt is used as electrolyte salt And, since irreversible capacity at the time of charge can be reduced, it is preferable.

  The solvent in the case of forming the negative electrode layer 12 using a conductive material, a binder, and a paste is the same as the material described for the positive electrode layer 11.

<Separator>
The separator 10 is not particularly limited as long as it is a porous film that functions as a separator for a non-aqueous electrolyte secondary battery and can form the above-described predetermined laminated structure.
Since the separator 10 can follow the surface shape of the positive electrode layer 11 or the negative electrode layer 12 and the ratio L2 / L1 and the ratio L4 / L3 described above are each within a predetermined range, the separator 10 is easy to form. Preferably, the fibrous material has an entangled porous structure.
The porous structure in which the fiber material is entangled is typically a woven structure or a non-woven structure, and a non-woven structure is preferable because the preparation of the separator 10 is easy.

  As a method of manufacturing the separator 10 of the porous structure in which the fiber material intertwined, after apply | coating the dispersion liquid containing a fiber material on the positive electrode layer 11 or the negative electrode layer 12, the method of removing a dispersion medium is preferable.

  The fiber material that can be used to form the separator 10 is not particularly limited as long as it is an insulating fiber material, and may be inorganic fibers or organic fibers.

  Preferred examples of the inorganic fibers include micro glass (glass fibers with a small diameter) and rock wool. Preferred examples of the organic fiber include cellulose fiber materials such as cellulose, carboxymethyl cellulose, cellulose esters such as cellulose acetate, and lignocellulose, neutral mucopolysaccharide fiber materials such as chitin and chitosan, and aliphatic nylon And fiber materials of synthetic resin based on resins such as polyamide such as aromatic nylon (aramid), polyolefin such as polyethylene and polypropylene, vinylon, polyester, polyimide, polyamide imide, polyvinylidene fluoride and the like. For synthetic resin fiber materials, fine fibers of synthetic resin can be obtained, for example, by a method such as electro spinning.

Among the above-mentioned fiber materials, it is easy to prepare and obtain a fiber material of a preferable size and easily obtain a fiber material well dispersed in a dispersion medium by modification treatment such as hydrophobization, cellulose, carboxymethyl cellulose, Cellulose esters such as cellulose acetate, cellulose fiber materials such as lignocellulose, and neutral mucopolysaccharide fiber materials such as chitin and chitosan are preferable, the above-mentioned cellulose fiber materials are more preferable, and cellulose is particularly preferable.
Cellulose at least partially oxidized and modified can also be preferably used as the fiber material.

  Hydrophobic modification | denaturation will not be specifically limited if it is the modification | reformation process which can improve the hydrophobicity of the surface of fiber material. Specifically, hydrophobic modification includes hydrophobic organic groups such as hydrocarbon groups and halogenated hydrocarbon groups, and hydrophobic functional groups such as organosiloxane structures and chemical structures on the surface of fiber materials. Treatment is preferred.

  The treatment for causing hydrophobic functional groups or chemical structures to exist on the surface of the fiber material is, for example, a treatment in which at least a part of the surface of the fiber material is coated with a modifying agent, Or the chemical bonding of the modifying agent to the surface of the fiber material.

  The volume average particle diameter of the fiber material is not particularly limited, but a porous film having a point that the fiber material can be well dispersed in the dispersion containing the fiber material, a desired porosity, and / or a desired average pore diameter From the viewpoint of easy formation, the thickness is preferably 5 μm to 100 μm, more preferably 5 μm to 70 μm, still more preferably 5 μm to 50 μm, particularly preferably 5 μm to 30 μm, and most preferably 5 μm to 20 μm.

The number average fiber diameter of the fiber material is preferably 2 nm or more and 500 nm or less, more preferably 2 nm or more and 100 nm or less, and particularly preferably 3 nm or more and 80 nm or less. When the number average fiber diameter of the fiber material is within the above range, the fiber material can be stably and favorably dispersed in the dispersion, and the desired porosity and / or the desired average pore diameter using the dispersion It is easy to form a porous membrane having
1000 nm or less is preferable and, as for the largest fiber diameter of the fiber material in a dispersion liquid, 500 nm or less is more preferable. When the maximum fiber diameter of the fiber material is within the above range, the fiber material is less likely to settle in the dispersion, and the fiber material is stably dispersed in the dispersion.

The number average fiber diameter and the maximum fiber diameter of the fiber material can be measured by the following method using, for example, a dispersion containing the fiber material. First, dilution or concentration is performed as necessary to adjust the solid content concentration of the dispersion to 0.05% by mass or more and 0.1% by mass. The solid solution concentration-adjusted dispersion is cast on a hydrophilized carbon film-coated grid to obtain a transmission electron microscope (TEM) observation sample.
When the dispersion contains fibers having a large fiber diameter, a scanning electron microscope (SEM) image of the surface cast onto glass may be observed.
Then, observation with an electron microscope image is performed at a magnification of 5000 times, 10000 times, or 50000 times depending on the size of the fibers to be configured. An axis of an arbitrary image width in the vertical and horizontal directions is assumed in the image obtained by observation with an electron microscope, and the sample and observation conditions (such as magnification) are adjusted so that 20 or more fibers intersect with the axis. Then, after obtaining an observation image that satisfies this condition, a random axis is drawn for each image in the vertical and horizontal directions for each image, and the fiber diameter of fibers intersecting with the axis is visually read. In this way, images of at least three non-overlapping surface portions are taken with an electron microscope, and the fiber diameter values of fibers intersecting each other on two axes are read (thus, at least 20 x 2 x 3 = 120) Information on the fiber diameter of the book is obtained). The maximum fiber diameter and the number average fiber diameter are calculated from the fiber diameter data thus obtained.

  When the separator 10 is formed using a dispersion containing a fiber material, an organic solvent is preferable as the dispersion medium contained in the dispersion. Preferred specific examples of the organic solvent include ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol (DPG), triethylene glycol, and glycols such as tripropylene glycol; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol Mono n-propyl ether, propylene glycol monomethyl ether (PGME), propylene glycol monoethyl ether, propylene glycol mono n-propyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono n-propyl ether, dipropylene glycol monomethyl ether ( MFDG), dipropylene glycol monoethyl Ether, dipropylene glycol mono n-propyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol mono n-propyl ether, tripropylene glycol monomethyl ether (MFTG), tripropylene glycol monoethyl ether, Glycol monoalkyl ethers such as tripropylene glycol mono n-propyl ether; 3-methoxybutyl acetate (MA), ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol mono n-propyl ether acetate, propylene glycol monomethyl ether Acetate (PGMEA), Propylene glycol monoethyl ester Acetate, propylene glycol mono n-propyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol mono n-propyl ether acetate, dipropylene glycol monomethyl ether acetate (DPMA), dipropylene glycol monoethyl ether acetate, Propylene glycol mono n-propyl ether acetate, triethylene glycol monomethyl ether acetate, triethylene glycol monoethyl ether acetate, triethylene glycol mono n-propyl ether acetate, tripropylene glycol monomethyl ether acetate, tripropylene glycol monoethyl ether acetate And glycol alkyl ether acetates such as tripropylene glycol mono n-propyl ether acetate; γ-butyrolactone (GBL), α-methyl-γ-butyrolactone, γ-valerolactone, γ-caprolactone, γ-laurolactone, δ- Valerolactone and lactones such as hexanolactone; methyl ethyl ketone, diethyl ketone, 2-pentanone, 2-hexanone, 2-hexanone, 3-hexanone, methyl isobutyl ketone, acetylacetone, cyclopentanone, cyclohexanone and cycloheptanone etc. Ketone; methanol, ethanol, n-propanol, isopropanol, n-butyl alcohol, isobutyl alcohol, sec-butyl alcohol, tert-butyl alcohol, n-pentyl alcohol Alkanemonools such as n-hexyl alcohol, cyclohexyl alcohol and n-heptyl alcohol; N, N-dimethylformamide (DMF), N, N-diethylformamide, N, N-dimethylacetamide (DMAc), N, N- Diethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N, N, N ', N'- tetramethylurea (TMU), N, N, N', N'- tetraethylurea, N And aprotic polar solvents such as methylcaprolactam, 1,3-dimethyl-2-imidazolidinone (DMI), dimethylsulfoxide, hexamethylphosphoric triamide, and acetonitrile.

  The organic solvent as the dispersion medium is typically used so that the solid content concentration of the dispersion is 0.1% by mass or more and 10% by mass or less, preferably 0.5% by mass or more and 3% by mass or less.

The porosity of the separator 10 is not particularly limited as long as the manufactured battery can operate. From the fact that, for example, lithium ions and the like are easily moved within the separator 10 and the mechanical strength of the separator 10 is good, the porosity of the separator 10 is 20% by volume or more and 80% by volume or less Preferably, 30% by volume or more and 70% by volume or less is more preferable, and 35% by volume or more and 60% by volume or less is particularly preferable.
The porosity can be adjusted by adjusting the dispersion diameter of the fiber material, the solid content concentration of the dispersion, the drying condition of the coating film when forming the separator 10, and the like.
The porosity of the separator 10 can be measured by a mercury porosimeter.

The average pore size of the separator 10 is not particularly limited. From the viewpoint of balance between ion permeability and short circuit risk, the average pore diameter of the separator 10 is preferably 0.02 μm or more and 0.18 μm or less, more preferably 0.02 μm or more and 0.15 μm or less, and 0.02 μm or more and 0.10 μm or less Particularly preferred.
The average pore diameter of the separator 10 can be adjusted by adjusting the dispersion diameter of the fiber material in the dispersion, the solid content concentration of the dispersion, the drying conditions of the coating film when forming the separator 10, and the like.
The average pore size of the separator 10 can be measured by a mercury porosimeter.

  The film thickness of the separator 10 is not particularly limited. The separator 10 is preferably as thin as possible because it can be charged at high speed and it is easy to produce a high capacity battery. Specifically, the film thickness of the separator 10 is preferably 1 μm to 100 μm, and more preferably 2 μm to 50 μm.

When the fiber material of the separator 10 has a entangled porous structure, the above-described active material is placed on the surface of the positive electrode layer 11 or the negative electrode layer 12 and protrudes, and the separator 10 has in the above-described laminated structure. It is preferred that the fibers are intercalated.
Whether or not the active material penetrates between the fibers of the separator 10 can be confirmed by a microscopic image of the cross section of the separator 10.
Thus, when the active material intrudes between the fibers of the separator 10, the adhesion between the separator 10 and the electrode becomes stronger. By doing this, the repeatability of the battery can be further improved.

<Current collector layer>
The current collector layer 13 is generally laminated on the surface of the positive electrode layer 11 and the negative electrode layer 12 opposite to the surface facing the separator 10.

Examples of the material of the current collector layer 13 stacked on the positive electrode layer 11 include aluminum, titanium, stainless steel, nickel, iron, calcined carbon, a conductive polymer, and a conductive glass.
In addition to these, aluminum, copper, etc. which are surface-treated with carbon, nickel, titanium, silver or the like, or whose surfaces are oxidized, are used as the positive electrode layer 11 for the purpose of improving adhesion, conductivity and oxidation resistance. It can be used as a material of the current collector layer 13 to be laminated.

Examples of the material of the current collector layer 13 to be laminated to the negative electrode layer 12 include copper, nickel, stainless steel, titanium, aluminum, sintered carbon, conductive polymer, conductive glass, Al-Cd alloy and the like. Be
Besides these, copper or the like which has been surface-treated with carbon, nickel, titanium, silver or the like or whose surface has been subjected to oxidation treatment is used for the negative electrode layer 12 for the purpose of improving adhesion, conductivity and oxidation resistance. It can be used as a material of the current collector layer 13 to be laminated.

Examples of the shape of the current collector include a foil, a film, a sheet, a net, a punched or expanded shape, a lath body, a porous body, a foam and the like.
In addition, as the current collector layer 13, a material having an air hole such as a porous body, a foam, a net, a punched sheet or the like can be adopted. When the paste for positive electrode formation or negative electrode formation is applied on the separator 10 as in the manufacturing method of the non-aqueous electrolyte secondary battery described later, and the current collector layer 13 having such a vent is provided The solvent etc. contained in the paste for positive electrode formation or for negative electrode formation becomes easy to escape.

<Electrolyte solution>
In the battery, the electrolytic solution is usually held between the positive electrode layer 11 and the negative electrode layer 12. As the electrolytic solution, a non-aqueous electrolytic solution obtained by dissolving an electrolyte in an organic solvent can be used.
As the electrolyte, for example _{LiPF 6, LiClO 4, LiBF 4} , LiAsF 6, and can be used at least one member selected from the group consisting of LiSbF ₆ like.
As the organic solvent, an aprotic organic solvent can be used. Preferable examples of the organic solvent include, for example, one or more selected from cyclic carbonate, linear carbonate, cyclic ester, cyclic ether, linear ether and the like.

  Examples of cyclic carbonates include ethylene carbonate, propylene carbonate, butylene carbonate and vinylene carbonate. Examples of chain carbonates include dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate and the like. Examples of cyclic esters include gamma butyrolactone and gamma valerolactone. Examples of cyclic ethers include tetrahydrofuran, 2-methyltetrahydrofuran and the like. Examples of the chain ether include 1,2-dimethoxyethane and the like.

  Preferably, the electrolytic solution is a non-aqueous electrolytic solution obtained by dissolving a lithium salt in an organic solvent. In this case, it is easy to obtain a high output battery.

For example, a stacked body in which the layers described above are stacked in the order of current collector layer 13 / positive electrode layer 11 / separator 10 / negative electrode layer 12 / current collector layer 13 is housed in a case, and positive electrode layer 11 and negative electrode layer 12 The battery is configured by holding the electrolytic solution therebetween. When the laminate is housed in the case, the laminate may be wound.
The shape of the case is not particularly limited, and may be a paper type, coin type, cylindrical type or the like.

«Method of manufacturing non-aqueous electrolyte secondary battery»
The method of manufacturing the above-described non-aqueous electrolyte secondary battery is not particularly limited as long as it can form the above-described predetermined laminated structure.
The preferred method is
In the step of forming the positive electrode layer 11 or the negative electrode layer 12 on the first current collector layer 13, the plurality of first protrusions 11 a may be provided on the positive electrode surface 11 b to form the positive electrode layer 11 or the negative electrode surface 12 b. Forming a plurality of second protrusions 12a to form the negative electrode layer 12;
A step of forming a coated film by applying a coating solution for forming a separator 10 containing a dispersion medium on the positive electrode layer 11 or the negative electrode layer 12 and then removing the dispersion medium from the coated film to form the separator 10 ,
A paste for forming a positive electrode or a negative electrode is applied on the separator 10 so that the positive electrode layer 11 or the negative electrode layer 12 of the first current collector layer 13 is opposed to the separator 10 via the separator 10. Forming a positive electrode layer 11 or a negative electrode layer 12 at a counter electrode to the layer formed on the first current collector layer 13;
And the step of forming the second current collector layer 13 on the positive electrode layer 11 or the negative electrode layer 12 which is the counter electrode to the layer formed on the first current collector layer 13.

Hereinafter, the method of forming the negative electrode layer 12 after the formation of the positive electrode layer 11 will be described with reference to FIGS. 2 (a) to 2 (e), for convenience.
In the method described below, the order of the formation of the positive electrode layer 11 and the formation of the negative electrode layer 12 can be reversed.

  First, as shown in FIG. 2A, the positive electrode precursor layer 15 made of the material of the positive electrode layer 11 is formed on the first current collector layer 13. The method for forming the positive electrode precursor layer 15 is not particularly limited. For example, the positive electrode precursor layer 15 may be formed by laminating a sheet made of the material of the positive electrode layer 11 with the first current collector layer 13. Also, as described above, even after the paste containing the material of the positive electrode layer 11 is applied on the first current collector layer 13, the solvent or dispersion medium in the paste is removed to form the positive electrode precursor layer 15. Good. Removal of the solvent or dispersion medium is typically performed by heating.

  As a method of forming the positive electrode precursor layer 15, after the paste containing the material of the positive electrode layer 11 is applied on the first current collector layer 13 because adjustment of the film thickness of the positive electrode precursor layer 15 is easy, etc. Preferred is a method of removing the solvent or dispersion medium in the paste.

  Examples of the paste application method include a roller coating method using an applicator roll or the like, a screen coating method, a doctor blade method, a spin coating method, a bar coating method and the like. The paste is applied by such a method to form the positive electrode precursor layer 15 of an arbitrary thickness.

Next, the positive electrode precursor layer 15 is processed to form a plurality of first protrusions 11a on the positive electrode surface 11b, to form the positive electrode layer 11 as shown in FIG. 2 (b).
Such a processing method is not particularly limited, and a pressing method, a laser ablation method, etc. may be mentioned, and the laser ablation method is preferable since the first projections 11 a can be formed with high precision in shape, size, position and the like.

After formation of the positive electrode layer 11, as shown in FIG. 2C, a coating liquid for forming the separator 10 containing a dispersion medium is applied onto the positive electrode layer 11 to form a coated film, and then dispersion from the coated film is performed. The medium is removed to form a separator 10.
As described above, as the coating solution, a coating solution containing a fiber material is preferable, and as the dispersion medium, an organic solvent is preferable.

The apparatus used for application of the dispersion is not particularly limited. As a coating device, for example, a contact transfer type coating device such as a roll coater, a reverse coater, or a bar coater, or a non-contact type coating device such as a curtain flow coater, a die coater, a slit coater, or a spray may be used.
Since a coating film having a uniform film thickness can be easily formed even on the surface where the unevenness is present, it is preferable to use a spray, for example, a rotary atomization type coating apparatus as a coating method. As a coating apparatus of a rotation atomization system, the apparatus described in Unexamined-Japanese-Patent No. 2013-115181 can be used, for example.

  On the formed separator 10, as shown in FIG. 2D, a paste for forming a negative electrode is applied so that the positive electrode layer 11 and the negative electrode layer 12 face each other with the separator 10 interposed therebetween. Form 12 At this time, the paste for forming the negative electrode is applied so as to be filled in the space between the first protrusions 11a. Usually, after coating, the negative electrode layer 12 is formed by removing the solvent or dispersion medium in the paste.

Thereafter, as shown in FIG. 2E, the second current collector layer 13 is formed on the negative electrode layer 12 which is the opposite electrode to the positive electrode layer 11 formed on the first current collector layer 13.
The method of forming the second current collector layer 13 is not particularly limited. For example, the second current collector layer 13 is provided on the negative electrode layer 12 by laminating the sheet-like second current collector layer 13 on the negative electrode layer 12.
It is also preferable to laminate the second current collector layer 13 made of a material having a vent hole on the negative electrode layer 12 before the negative electrode layer 12 is dried. In this case, since the second current collector layer 13 can be closely adhered while removing the solvent or the dispersion medium contained in the negative electrode layer 12, a battery having more excellent usability can be produced.

  The nonaqueous electrolyte secondary battery is suitably manufactured by the method described above.

  EXAMPLES Hereinafter, the present invention will be specifically described by way of examples. However, the scope of the present invention is not limited to the examples shown below.

Example 1
A copper foil with a thickness of 20 μm was used as a current collector layer on the negative electrode layer side. Paste for negative electrode formation which dispersed graphite (solid content concentration 85 mass%), styrene butadiene rubber (SBR; solid content concentration 5 mass%), carboxymethyl cellulose (solid content concentration 5 mass%) on a copper foil with water Was applied by screen printing, and then the coated film was dried to form a negative electrode precursor layer having a thickness of 140 μm.

The negative electrode precursor layer was processed by laser ablation to form a negative electrode layer having a concavo-convex structure such that the plurality of second protrusions were projected from the negative electrode surface. For the negative electrode layer, the average of the distance from the surface of the copper foil to the negative electrode surface was 35 μm, and the average of the protruding heights of the second protrusions from the negative electrode surface was 105 μm.
The angle between the negative electrode surface and the side surface of the second protrusion was 60 °.

  Next, a spray method is used to form a coating solution for forming a separator, which contains 0.5% by mass of a cellulose in which a part of the hydroxyl groups (methylol groups) possessed has been oxidatively modified to carboxy groups with respect to the dispersion medium N-methylpyrrolidone. After coating on the negative electrode layer, the coated film was dried to form a separator having a thickness in the range of 12 μm to 23 μm.

After formation of the separator, lithium cobalt complex oxide (solid content concentration 80 mass%), acetylene black (solid content concentration 12 mass%), polyvinylidene fluoride (solid content concentration 8 mass%) on the separator, N-methylpyrrolidone Is applied by screen printing so that the space between the second protrusions is filled with paste, and then the coating film is dried to have a concavo-convex structure on the surface on the separator side. Then, a positive electrode layer was formed in which the surface opposite to the surface on the separator side is a flat surface.
With respect to the positive electrode layer, the average of the distance from the flat surface to the positive electrode surface was 45 μm, and the average of the protruding heights of the first protrusions from the positive electrode surface was 85 μm.

After formation of the positive electrode layer, a 20 μm thick aluminum foil having an opening formed by punching is laminated on the flat surface of the positive electrode layer to obtain a laminate including the positive electrode layer, the negative electrode layer, and the separator. The
In the obtained laminate, the value of L2 / L1 and the value of L4 / L3 described above were both 1.00.

A mixed solution of ethylene carbonate and diethyl carbonate in a ratio of 1: 1 (volume ratio) containing 1 mol / L of LiPF ₆ as an electrolyte is used as an electrolytic solution, and the electrolytic solution and the laminate of the above are enclosed in an aluminum laminate film Thus, a non-aqueous electrolyte secondary battery was obtained. The designed battery capacity of the non-aqueous electrolyte secondary battery was 7.8 mAh.

Example 2
Setting the average of the distance from the surface of the copper foil to the negative electrode surface of the negative electrode layer to 25 μm and the average of the protruding heights of the second protrusions from the negative electrode surface to 100 μm;
Setting an angle between the negative electrode surface and the side surface of the second projection to 75 °;
Setting the average of the distance from the flat surface to the positive electrode surface of the positive electrode layer to 60 μm and the average of the protruding heights of the first protrusions from the positive electrode surface to 100 μm;
A laminate was obtained in the same manner as in Example 1 except that the film thickness of the separator was in the range of 9 μm to 15 μm, and then a non-aqueous electrolyte secondary battery was obtained.
In the obtained laminate, the value of L2 / L1 and the value of L4 / L3 described above were both 1.00.
In addition, the designed battery capacity of the non-aqueous electrolyte secondary battery was 7.8 mAh.

Comparative Example 1
A flat negative electrode layer with a thickness of 130 μm was formed on a copper foil with a thickness of 20 μm by the same method as the method for forming the negative electrode precursor layer in Example 1.
On the formed negative electrode layer, a separator having a thickness in the range of 6 μm to 7 μm was formed in the same manner as in Example 1.
On the formed separator, the paste for positive electrode formation was apply | coated by the method similar to Example 1, Then, a coating film was dried and the flat positive electrode layer with a film thickness of 100 micrometers was formed.
An aluminum foil having a thickness of 20 μm, having an opening formed by punching, was laminated on the formed positive electrode layer to obtain a laminate including the positive electrode layer, the negative electrode layer, and the separator.
A non-aqueous electrolyte secondary battery was obtained as in Example 1 using the obtained laminate. The designed battery capacity of the non-aqueous electrolyte secondary battery was 6.0 mAh.

The values obtained by dividing the battery capacity by the weight of the active material (g) of the non-aqueous electrolyte secondary batteries obtained in Example 1 and Example 2 and Comparative Example 1 were 59.86 mAh / g in Example 1. In Example 2, it was 66.34 mAh / g, and in Comparative Example 1, it was 45.50 mAh / g.
From this, it is understood that the nonaqueous electrolyte secondary batteries of Examples 1 and 2 satisfying the predetermined requirements have high capacity.

Further, for the non-aqueous electrolyte secondary batteries obtained in Example 1, Example 2, and Comparative Example 1, when the charge / discharge capacity values were compared at C rate 0.1, 1, 2, and 3, It was confirmed that the values of the charge and discharge capacities of Example 1 and Example 2 were higher than the value of the charge and discharge capacities of Comparative Example 1.
From this, it is understood that the non-aqueous electrolyte secondary batteries of Examples 1 and 2 satisfying the predetermined requirements are excellent in high-speed charge performance.
In addition, since the value of the charge / discharge capacity of Example 2 is higher than the value of the charge / discharge capacity of Example 1, when the cross-sectional shapes of the first protrusion and the second protrusion are trapezoidal, The larger the angle between the positive electrode surface and the angle between the second protrusion and the negative electrode surface, the higher the high-speed charging performance.
Further, in all the laminates in the section of this example, the values of L2 / L1 and L4 / L3 were 1.00. In the case of stacking an electrode having a concavo-convex structure through a separator, the value of L2 / L1 and the value of L4 / L3 become low in the usual method. In the laminate of this example, since the L2 / L1 value and the L4 / L3 value can achieve high values, peeling between the electrode and the separator is also less likely to occur, and the battery is excellent in repetitive usability and the like. Can be achieved. In addition, since the values of L2 / L1 and L4 / L3 can achieve high values, an effect that the volume of the entire battery can be reduced can also be expected.

DESCRIPTION OF SYMBOLS 10 separator 11 positive electrode layer 11a 1st protrusion 11b positive electrode surface 12 negative electrode layer 12a 2nd protrusion 12b negative electrode surface 13 collector layer 14 positive electrode precursor layer

Claims (9)

A non-aqueous electrolyte secondary battery having a laminated structure in which a positive electrode layer, a separator, and a negative electrode layer are laminated in this order,
The positive electrode layer has a plurality of first protrusions protruding from the positive electrode surface in the separator direction,
The negative electrode layer has a plurality of second protrusions protruding from the negative electrode surface in the separator direction,
In the positive electrode layer and the negative electrode layer, the first protrusions are located in the space between the adjacent second protrusions, and the second protrusions are located in the space between the adjacent first protrusions. And so on,
When a cross section of the laminated structure including the positive electrode layer, the negative electrode layer, and the separator is observed, the total length of the outline A1 of the surface of the separator facing the positive electrode surface in the cross section is L1. When the total length of the outline B1 of the concavo-convex structure defined by the plurality of first projections is L2, the ratio L2 / L1 is 0.95 or more and 1.05 or less,
The ratio when the total length of the outline A2 of the surface of the separator facing the negative electrode surface in the cross section is L3 and the total length of the outline B2 of the concavo-convex structure defined by the plurality of second protrusions is L4 The nonaqueous electrolyte secondary battery whose L4 / L3 is 0.95 or more and 1.05 or less.   The non-aqueous electrolyte secondary battery according to claim 1, wherein the separator has a porous structure in which fibers are intertwined.   The non-aqueous electrolyte secondary battery according to claim 2, wherein an active material protrudes on the surface of the positive electrode layer and the negative electrode layer, and the active material penetrates between the fibers of the separator.   The average of the protrusion heights of the plurality of first protrusions from the positive electrode surface and the average of the protrusion heights of the plurality of second protrusions from the negative electrode surface are each 5 μm or more. The nonaqueous electrolyte secondary battery according to any one of the above.   The non-aqueous electrolyte secondary battery according to any one of claims 1 to 4, wherein the separator is made of cellulose. It is a method of manufacturing the nonaqueous electrolyte secondary battery according to any one of claims 1 to 5,
A step of forming the positive electrode layer or the negative electrode layer on a first current collector layer, wherein a plurality of the first protrusions are provided on the positive electrode surface to form a positive electrode layer, or on the negative electrode surface, Providing a plurality of the second protrusions to form a negative electrode layer;
A coating solution for forming a separator containing a dispersion medium is applied onto the positive electrode layer or the negative electrode layer to form a coated film, and then the dispersion medium is removed from the coated film to form the separator. Process,
A paste for forming a positive electrode or a negative electrode is applied on the separator, and the positive electrode layer or the negative electrode layer on the first current collector layer is opposed to the other through the separator. Forming the positive electrode layer or the negative electrode layer on the opposite electrode to the layer formed on the first current collector layer;
A step of forming a second current collector layer on the positive electrode layer or the negative electrode layer, which has a counter electrode to the layer formed on the first current collector layer, a nonaqueous electrolyte secondary battery Manufacturing method.   The manufacturing method of the nonaqueous electrolyte secondary battery of Claim 6 in which the said coating liquid contains a fiber material.   The average of the protrusion heights of the plurality of first protrusions from the positive electrode surface and the average of the protrusion heights of the plurality of second protrusions from the negative electrode surface are each 5 μm or more. The manufacturing method of the non-aqueous electrolyte secondary battery as described in-.   The manufacturing method of the nonaqueous electrolyte secondary battery according to any one of claims 6 to 8, wherein the second current collector layer has a vent.

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