KR20150070939A - Secondary battery and preparation method thereof - Google Patents

Abstract

A secondary battery and a preparation method thereof are disclosed. The secondary battery comprises an electrode layer forming area and an electrode layer non-forming area on the surface of an electrode collector of each of a first electrode structure and a second electrode structure. The electrode layer forming area includes the electrode layer non-forming area including an electrode collecting tap binding area. The secondary battery is made by surrounding the first electrode structure, the second electrode structure, and an electrolyte layer between them with an exterior and integrating them by pressurizing.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a secondary battery and a secondary battery,

A secondary battery, and a method of manufacturing the secondary battery.

The secondary battery is a device capable of repeating charging and discharging while moving charges through an electrolyte disposed between an anode and a cathode.

2. Description of the Related Art In recent years, a secondary battery, for example, a lithium ion secondary battery, has a structure that surrounds a cell with an external body using an aluminum laminate film or the like in response to a demand for thinning.

A cell of a lithium ion secondary battery generally comprises a positive electrode structure in which a positive electrode layer is formed on the surface of a positive electrode collector and a positive electrode collector tab is bonded to the positive electrode collector, a negative electrode structure in which a negative electrode layer is formed on the surface of the negative electrode collector, And an electrolyte layer disposed between the cathode structure and the cathode structure. When the layers are laminated, the positive electrode current collecting tab and the negative electrode current collecting tab are bonded to the respective electrode structures at positions where the layers are separated from each other.

On the other hand, in order to improve the energy density of the lithium ion secondary battery, it is required that the area of the electrode layer is large. In order to secure a large area of the electrode layer, the electrode current collecting tab junction region may be provided so as to protrude from the electrode layer forming region.

However, in the structure in which the electrode current collecting tab junction region protrudes from the electrode layer forming region, the electrode current collecting tab junction region is liable to be broken by the pressurizing treatment performed in manufacturing the battery. In addition, when the shape of the structure is surrounded by the outer body, the energy density of the lithium ion secondary battery can be suppressed.

Therefore, there is a need for a secondary battery having a structure for preventing breakage of the current collecting tap junction region and improving energy density.

One aspect of the present invention provides a secondary battery capable of avoiding breakage of the current collecting tab junction region and improving production efficiency and energy density.

Another aspect provides a method of manufacturing the secondary battery.

According to one aspect,

A secondary battery comprising an electrode layer forming region and an electrode layer non-forming region on a surface of an electrode collector of each of the first electrode structure and the second electrode structure,

And an electrode layer non-formation region including an electrode current collecting tab junction region in the electrode layer formation region,

Wherein the first electrode structure, the second electrode structure, and the electrolyte layer disposed between the first electrode structure and the second electrode structure are surrounded by an external body and integrated by pressure treatment.

According to another aspect,

An electrode coating liquid containing a first electrode active material or a second electrode active material is coated on the surfaces of the first electrode current collector and the second electrode current collector to form first electrode layers and second electrode layers, Forming an electrode layer non-formation region including a junction region;

Forming a first electrode structure and a second electrode structure by bonding an electrode current collecting tab to the electrode current collecting tab junction region; And

Forming an electrolyte layer between the first electrode structure and the second electrode structure, and surrounding the electrolyte layer with an external body and integrating the electrolyte layer by pressurization to manufacture a secondary battery.

According to an aspect of the present invention, it is possible to prevent breakage of the electrode current collecting tab junction region, thereby improving the production efficiency of the secondary battery. In addition, the volume of the cells of the secondary battery including the first electrode structure, the electrolyte layer, and the second electrode structure may be reduced to reduce the amount of the outer body surrounding the cells. Thus, the energy density of the secondary battery can be improved.

1A is a schematic plan view showing an electrode structure 100 of an embodiment.
1B shows a state in which the electrode current collecting tab 104 is bonded to the electrode current collecting tab junction region 102 (the region where the electrode current collector 103 of the electrode current collector 103 is formed), and then the external electrode 106 and the sealant 105 are sealed 1 is a schematic plan view showing an exemplary electrode structure 100. Fig.
2A is a schematic plan view showing an electrode structure 200 of a comparative example.
2B shows a comparison in which the electrode current collecting tabs 204 are bonded to the electrode current collecting tab junction region 202 (the electrode layer non-formation region of the electrode current collector 203) and then the external electrode 206 and the sealant 205 are sealed 2 is a schematic plan view showing an exemplary electrode structure 200. Fig.
3 is a cross-sectional schematic diagram illustrating a pre-solid battery according to one embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the present invention will become more apparent by referring to the embodiments described in detail below with reference to the accompanying drawings. However, the embodiments of the present invention are not limited to the embodiments described below, but may be implemented in various other forms. The present embodiments are provided so that the disclosure of the present invention is not limited thereto and that those skilled in the art will fully understand the scope of the present invention. Embodiments of the invention are only defined by the scope of the claims.

It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. In the present specification, the singular form includes plural forms unless otherwise specified in the specification. The terms " comprises "and / or" comprising ", as used herein, mean that a component, step, operation and / And does not exclude the presence or addition thereof. The terms first, second, etc. may be used to describe various elements, but the elements should not be limited by terms. Terms are used only for the purpose of distinguishing one component from another.

As used herein, the terms "first electrode structure" and "second electrode structure" are constructions that are opposite to each other and mean "anode structure" and "cathode structure" or "cathode structure" and "anode structure" do.

In the present specification, the "electrode current collector" is included as the "first electrode current collector" or the "second electrode current collector" in the "first electrode structure" and the "second electrode structure", respectively.

In the present specification, "electrode layer forming region" means a region on the electrode collector surface carrying the electrode active material and includes "first electrode layer forming region" or "second electrode layer forming region ".

In the present specification, "electrode layer non-formation region" means a region on the electrode current collector surface where the electrode active material is not supported, and includes the "first electrode layer non-formation region"

As used herein, the term "on a face" includes the meaning of "on top of direct contact with a face ", or" on a single layer or a plurality of layers such as an adhesion layer without direct contact with a face ".

As used herein, the term "(outermost) edge" means the (outer) outer edge of a circular or polygonal shape.

Hereinafter, a secondary battery and a method for manufacturing the secondary battery according to embodiments of the present invention will be described in detail. The lithium ion secondary battery will be described in further detail as an embodiment of the secondary battery.

2A is a schematic plan view showing an electrode structure of a comparative example. 2B shows a comparison in which the electrode current collecting tabs 204 are bonded to the electrode current collecting tab junction region 202 (the electrode layer non-formation region of the electrode current collector 203) and then the external electrode 206 and the sealant 205 are sealed 2 is a schematic plan view showing an exemplary electrode structure 200. Fig.

In FIGS. 2A and 2B, reference numeral 200 denotes an electrode structure, reference numeral 201 denotes an electrode layer formed on the surface of the electrode current collector 203, and reference numeral 202 denotes an electrode current collecting tab junction region. The electrode structure 200 is a first electrode structure or a second electrode structure.

As shown in Fig. 2B, one end of the electrode current collecting tab 204 is exposed to the outside of the external body 206 for connection to a lead (not shown). In FIG. 2B, only the electrode structure is shown to simplify the description, but in a practical lithium ion secondary battery, a cell made up of two electrode structures and an electrolyte layer is enclosed by an external body. Therefore, the electrode current collecting tab 204 also surrounds another electrode current collecting tab (not shown) in the exposed position with the external body.

However, since the electrode assembly 200 of the comparative example shown in Figs. 2A and 2B has a structure in which the electrode current collecting tab junction region 202 protrudes from the electrode layer forming region, The current collecting tab junction region 202 (the electrode layer non-formation region of the electrode current collector 203) tends to break. Also, when the electrode structure 200 of the comparative example is surrounded by the case 206, the amount of the case may be increased and the energy density may be lowered.

[Secondary Battery: Lithium Ion Secondary Battery]

According to an aspect of the present invention, a secondary battery includes an electrode layer forming region and an electrode layer non-forming region on a surface of an electrode collector of each of the first electrode structure and the second electrode structure, And an electrode layer non-formation region including a bonding region, and the first electrode structure, the second electrode structure, and the electrolyte layer disposed therebetween are surrounded by an external body and integrated by pressure treatment.

The first electrode structure and the second electrode structure will be described with reference to Figs. 1A and 1B.

1A is a schematic plan view showing an electrode structure of an embodiment. 1B shows a state in which the electrode current collecting tab 104 is bonded to the electrode current collecting tab junction region 102 (the region where the electrode current collector 103 of the electrode current collector 103 is formed), and then the external electrode 106 and the sealant 105 are sealed 1 is a schematic plan view showing an exemplary electrode structure 100. Fig.

1A and 1B, reference numeral 100 denotes an electrode structure, and reference numeral 101 denotes an electrode layer formed on the surface of the electrode current collector 103. (102) is an electrode current collecting tab junction region. The electrode current collecting tab junction region 102 is in a state where the electrode current collector 103 is exposed because it is in the electrode layer non-formation region on the surface of the electrode current collector 103. However, the electrode current collecting tab junction region 103 of the present invention does not protrude in the surface direction of the electrode current collector 103. The first electrode structure and the second electrode structure both have the above structure.

An electrolyte layer (not shown) is disposed between the two electrode structures to assemble the cell. The cell is surrounded by an enclosure 106 and is sealed with an enclosure 106 and a sealant 105. 1B is a cell sealed with an enclosure 106 and a sealant 105. Fig. In FIG. 1B, only the electrode structure 100, for example, the first electrode structure is shown for the sake of simplicity. However, in a secondary battery, for example, a lithium ion secondary battery, The electrode current collecting tab of the second electrode structure is also exposed at the position spaced apart from the electrode current collecting tab 104.

The electrode current collecting tab junction region 102 may be formed anywhere in the electrode layer forming region. However, when the electrode current collecting tab junction region 102 is too wide, it leads to a shortage of the electrode layer, resulting in a decrease in the energy density. Therefore, it is necessary to minimize the area of the electrode current collecting tab junction region 102 and to secure the electrode layer 101 as much as possible.

As shown in Figs. 1A and 1B, the electrode current collecting tab junction region 102 is located at the outermost portion of the electrode layer forming region. The shape of the electrode current collecting tab junction region 102 may include a circle or a polygon. In the case of a polygon, a triangle or a quadrangle is preferable, and from the viewpoint of ease of manufacture, a quadrangle is more preferable.

As a result, the electrode current collecting tab junction region 102 is surrounded by the electrode layer 101 in two or more directions on its outer periphery. Therefore, the outer edge portion of the electrode current collecting tab junction region 102 (the electrode layer non-formation region of the electrode current collector 103) can be supported by the electrode layer formation region in two or more directions parallel to the surface direction. The term "surface direction" means the horizontal or vertical direction of the current collector.

As a result, even if the electrode current collecting tab junction region 102 (the electrode layer non-formation region of the electrode current collector 103) is subjected to a pressing process to integrate the respective layers later, the electrode current collecting tab junction region 102 The electrode layer non-formation region of the entirety 103) does not break. Therefore, the secondary battery of the present invention, for example, a lithium ion secondary battery is excellent in pressure resistance, and more specifically, even when pressure treatment of 294 MPa to 980 MPa is performed, the electrode current collecting tab junction region 102 103 in the electrode-layer non-formation region) can be prevented. That is, by improving the electrode structure 100, the manufacturing efficiency of the lithium ion secondary battery can be improved.

In Fig. 1B, the shape of the electrode current collecting tab junction region 102 is rectangular. The outer edge portion of the electrode current collecting tab junction region 102 is supported by the electrode layer forming region in three directions parallel to the surface direction. The arrows shown in Fig. 1B indicate the supporting direction of the electrode current collecting tab 104 by the electrode layer 101. Fig. As another example, the electrode current collecting tab junction region 102 can be supported in two directions parallel to the plane direction in the case of a triangle, and in five directions parallel to the plane direction in the case of a hexagon. In other words, in the case of forming the n-type electrode current collecting tab junction region 102, the electrode current collecting tab junction region 102 is supported in the (n-1) direction parallel to the surface direction by the electrode layer forming region of the electrode current collector . When the electrode current collecting tab 104 having a shape corresponding thereto is to be joined, the electrode current collecting tab 104 can be supported in the (n-1) direction parallel to the surface direction by the electrode layer 101.

1B, the electrode structure 100 includes an electrode current collecting tab 104 joined to the electrode current collecting tab junction region 102 and having one end protruded from the electrode current collector. The electrode current collecting tab 104 can be supported by the electrode layer 101 formed in the electrode layer forming region in two or more directions parallel to the surface direction. Therefore, the electrode current collecting tab junction region 102 becomes large enough to form the electrode current collecting tab junction region 102 inside the electrode layer forming region.

As a result, the area of the electrode current collecting tab junction region 102 may be 0.8% to 1.3% based on the total area of the electrode collector. When the area of the electrode current collecting tab junction region 102 is 1.3% or more, that is, the electrode layer area is less than 98.7%, the energy density of the lithium ion secondary battery may be lowered. When the electrode layer area is 99.2% or more, the area of the electrode current collecting tab junction region 102 becomes less than 0.8%. In this case, the bonding area of the electrode current collecting tab 104 becomes small, and the bonding force is reduced, and the electrode current collecting tab 104 may be broken.

By forming the electrode current collecting tab junction region with the above-described mode, it is possible to form a cell of a secondary battery cell having no protruding portion. The electrode structure 100 reduces 5% to 15% in weight and 3% to 5% in volume as compared with the electrode structure having protruding portions such as the electrode structure 200 in Figs. 2A and 2B can do. As a result, the amount of use of the external body can be suppressed, and the lowering of the energy density due to the resistance of the external body can be suppressed. Therefore, even if the area of the electrode layer is reduced, the energy density reduction attributed to the structure of the electrode structure is canceled by the reduction in the amount of the outer body used, and as a result, the energy density of the lithium ion secondary battery can be improved. The lithium ion secondary battery may be used in a mobile device, a hybrid vehicle, an electric vehicle, or a power tool.

The first electrode structure and the second electrode structure have the same constitution except that the content of the electrode layer is different. The first electrode structure and the second electrode structure include a cathode active material on one of the electrode layers and a negative electrode active material on the other electrode layer. In the following description, the first electrode structure is referred to as a positive electrode structure and the second electrode structure is referred to as a negative electrode structure for the sake of convenience.

The positive electrode layer constituting the positive electrode structure contains the positive electrode active material and the binder, and is formed on the surface of the positive electrode collector.

As the positive electrode collector, a material having conductivity may be used, and for example, aluminum, stainless steel, nickel-plated steel, or the like may be used.

The positive electrode active material can be any compound capable of reversibly intercalating and deintercalating lithium ions. The compound capable of reversibly intercalating and deintercalating lithium ions is not particularly limited, but specific examples thereof include Li _a A _{1 - b} B _b D ₂ wherein 0.90 ≤ a ≤ 1.8, and 0 ≤ b ≤ 0.5); Li _a E _{1 - b} B _b O _{2 - c} D _{c where} 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05; LiE _{2 - b} B _b O _{4 - c} D _{c where} 0? B? 0.5, 0? C? 0.05; Li _a Ni _{1 -b- c} Co _b B _c D _? Wherein, in the formula, 0.90? A? 1.8, 0? B? 0.5, 0? C? 0.05, 0 <? Li _a Ni _{1 -b- c} Co _b B _c O _{2 - ?} F _{? Wherein} , in the formula, 0.90? A? 1.8, 0? B? 0.5, 0? C? 0.05, 0 <? Li _a Ni _{1 -b- c} Co _b B _c O _{2 - ?} F ₂ wherein 0.90? A? 1.8, 0? B? 0.5, 0? C? 0.05, 0 <? Li _a Ni _1-bc Mn _b B _c D _? Wherein, in the formula, 0.90? A? 1.8, 0? B? 0.5, 0? C? 0.05, 0 <? Li _a Ni _{1 -b- c} Mn _b B _c O _{2 - ?} F _{? Wherein} , in the formula, 0.90? A? 1.8, 0? B? 0.5, 0? C? 0.05, 0 <? Li _a Ni _{1 -b- c} Mn _b B _c O _{2 - ?} F ₂ wherein 0.90? A? 1.8, 0? B? 0.5, 0? C? 0.05, 0 <? Li _a Ni _b E _c G _d O ₂ wherein 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, and 0.001 ≤ d ≤ 0.1; Li _a Ni _b Co _c Mn _d G _e O ₂ wherein 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0 ≤ d ≤ 0.5, and 0.001 ≤ e ≤ 0.1; Li _a NiG _b O ₂ (in the above formula, 0.90? A? 1.8, and 0.001? B? 0.1); Li _a CoG _b O ₂ wherein, in the above formula, 0.90? A? 1.8, and 0.001? B? 0.1; Li _a MnG _b O ₂ (in the above formula, 0.90? A? 1.8, 0.001? B? 0.1); Li _a Mn ₂ G _b O ₄ wherein, in the above formula, 0.90? A? 1.8, and 0.001? B? 0.1; LiQO _2; LiQS ₂ ; LiV ₂ O ₅ ; LiIO ₂ ; LiNiVO _4; Li _(3-f) J ₂ (PO ₄ ) ₃ (0? F? 2); Li _(3-f) Fe ₂ (PO ₄ ) ₃ (0? F? 2), and LiFePO ₄ .

More specifically, lithium cobalt oxide (hereinafter referred to as &quot; LCO &quot;), lithium nickel oxide, lithium nickel cobaltate, lithium nickel cobalt aluminum oxide (hereinafter abbreviated as NCA), nickel cobalt lithium manganese oxide Quot; NCM &quot;), lithium manganese oxide, lithium iron phosphate, nickel sulfide, copper sulfide, sulfur, iron oxide, or vanadium oxide. These cathode active materials may be used singly or in combination of two or more kinds. The positive electrode active material may contain 75 to 99 parts by weight based on 100 parts by weight of the positive electrode layer as a main component of the positive electrode layer.

The cathode active material may be, for example, a lithium salt of a transition metal oxide having a layered rock salt type structure. &Quot; Layered &quot; means a thin sheet-like shape. &Quot; Salt-like structure &quot; refers to a structure in which a chloride-sodium-type structure is one type of crystal structure, and the face-centered cubic lattices formed by positive and negative ions are displaced from each other by ½ of the corner of the unit lattice. The lithium salt of the transition metal oxide having the layered _halide salt structure may be, for example, Li _{1 -xy- z} Ni _x Co _y Al _z O ₂ (NCA) or Li _{1 -xyz} Ni _x Co _y Mn _z O ₂ (NCM) (0 <x <1, 0 <y <1, 0 <z <1, and x + y + z <1).

Examples of the binder include a styrene-butadiene rubber (SBR), a butadiene rubber (BR), a nitrile rubber (NMR), a styrene butadiene block copolymer (SBS), a styrene ethylene butadiene styrene block copolymer (SEB) (NR), isoprene rubber (IR), or an ethylene-propylene-diene terpolymer (EPDM) may be cited as examples of the styrene-based thermoplastic elastomer. These binders may be used alone or in combination.

When a solid electrolyte is used for the electrolyte layer, a solid electrolyte may be included in the anode layer to increase the interface with the cathode active material and the electrolyte component. The solid electrolyte may be a phosphoric acid solid electrolyte or a sulfide solid electrolyte. A sulfide-based solid electrolyte having a high ionic conductivity may be more preferably used.

The anode layer may also contain carbon black, graphite, fine natural graphite, artificial graphite, acetylene black, Ketjen black, carbon fiber; Metal powders or metal fibers or metal tubes such as carbon nanotubes, copper, nickel, aluminum, and silver; A conductive polymer such as a polyphenylene derivative, and the like may be used, but the present invention is not limited thereto, and any conductive material may be used as the conductive material in the related art.

The negative electrode layer constituting the negative electrode structure contains a negative electrode active material and a binder, and is formed on the surface of the negative electrode collector.

As the negative electrode collector, a material having conductivity may be used, and for example, copper, stainless steel, or nickel-plated steel may be used.

The negative electrode active material may be a lithium metal, a metal material capable of alloying with lithium, a transition metal oxide, a material capable of doping and dedoping lithium, or a material capable of reversibly intercalating and deintercalating lithium ions.

Specific examples of the transition metal oxide include vanadium oxide and lithium vanadium oxide. Examples of the material capable of doping and dedoping lithium include Si, SiO _x (0 <x <2), Si-Y alloy (Y Sn, SnO ₂ , Sn-Y (wherein Y is an alkali metal, an alkali earth metal, an alkaline earth metal, a Group 13 element to a Group 16 element, a transition metal, a rare earth element or a combination element thereof, A Group 13 element to a Group 16 element, a transition metal, a rare earth element, or a combination element thereof, but not Sn), and at least one of them may be mixed with SiO ₂ . The element Y may be at least one element selected from the group consisting of Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ti, Ge, P, As, Sb, Se, Te, Po, or a combination thereof.

As a material capable of reversibly intercalating and deintercalating lithium ions, any carbonaceous anode active material commonly used in lithium ion secondary batteries can be used as the carbonaceous material. Typical examples thereof include crystalline carbon, amorphous carbon, Can be used together. Examples of the crystalline carbon include graphite such as natural graphite or artificial graphite in an amorphous, plate-like, flake-like, spherical or fibrous form. Examples of the amorphous carbon include soft carbon (soft carbon) Or hard carbon, mesophase pitch carbide, fired coke, and the like.

The negative electrode active material is a mixture of a graphite active material such as, for example, artificial graphite, natural graphite, a mixture of artificial graphite and natural graphite, natural graphite coated with artificial graphite, and fine particles of silicon or tin or oxides thereof, Fine particles of silicon or tin, alloys based on silicon or tin, or titanium oxide based compounds such as Li ₃ Ti ₅ O ₁₂ can be used.

The binder may be the same as the binder used for the anode layer. In some cases, the conductive material used for the anode layer may be used as well.

The electrode current collecting tabs constituting the anode structure and the cathode structure are made of copper, aluminum, nickel or the like, and a part thereof is bonded to the electrode current collecting tab junction region of the electrode structure. Examples of the bonding method include resistance welding, ultrasonic welding, and the like.

The electrolyte layer may comprise a solid electrolyte. The electrolyte layer may include a known aqueous electrolyte, a non-aqueous electrolyte, an ionic liquid, or a polymer gel electrolyte. The solid electrolyte may be, for example, a sulfide-based solid electrolyte, an oxide-based solid electrolyte, or a phosphoric acid-based solid electrolyte.

The solid electrolyte may include a sulfide-based compound. Sulfide-based solid electrolytes are advantageous because of their high ionic conductivity. The ion conductivity of the solid electrolyte is preferably as large as possible, specifically 10 ^-5 S / cm or more, more preferably 10 ^-4 S / cm or more.

The solid electrolyte may be an amorphous crystal.

The sulfide-based compound may be a sulfide including lithium (Li), phosphorus (P), and sulfur (S). Specific examples of the sulfide-based compound may include Li ₇ P ₃ S ₁₁ , Li ₃ PS ₄ , Li ₇ PS ₆ , or Li ₆ PS ₅ Cl.

The ion conductivity of the solid electrolyte depends on the particle diameter and specific surface area. Accordingly, the average particle diameter of the solid electrolyte, for example, the sulfide-based compound may be 0.1 탆 to 100 탆, and may be, for example, 5 탆 to 50 탆. The average particle size of the solid electrolyte can be determined by measuring the particle diameter of 50 solid electrolyte particles arbitrarily selected by using a dry particle size analyzer, and the average value of the measured values can be taken as an average particle diameter.

The specific surface area of the solid electrolyte, for example, the sulfide-based compound may be at least 0.1 m ² / g or more, for example, 1 m ² / g or more. The larger the specific surface area of the solid electrolyte, the larger the interface with the electrode active material and the ion conduction path can be increased. The specific surface area of the solid electrolyte can be measured using a specific surface area meter. The solid electrolyte layer may contain the above-mentioned known binder in addition to the solid electrolyte.

The outer body may be formed of a material having flexibility, liquid tightness, and airtightness. Having "flexibility" refers to the property of curving by force from the outside. The term "liquid tightness" means that the liquid is not permeable to liquid. Having the "airtightness" means that it is not gas permeable. By providing flexibility, the cell including the first electrode structure, the electrolyte layer, and the second electrode structure can be formed into a shape capable of encapsulating the cell. By providing liquid tightness and airtightness, contact between the cell and the outside air can be suppressed, and leakage of constituent components of the enclosed cell can be prevented.

The outer body may be formed of a material having a film made of a thermo-compressible resin on the surface of the metal material. A specific example of the outer body may be a film of a metal material such as aluminum or stainless which is thermally press-bondable. Examples of the thermocompressible resin include polypropylene, polyolefin resins such as polyethylene, and heat-resistant polyester resins. A sheet or film made of the above-described material can be molded into a shape capable of encapsulating a cell made of an electrode structure and an electrolyte layer to form an external body of the present invention.

The pressurizing treatment may be a hydrostatic pressure treatment. The cell surrounded by the casing by hydrostatic treatment is pressed and compacted in all directions. In the secondary battery according to an embodiment, since the junction region between the electrode current collector and the current collecting tab is supported in two or more directions parallel to the surface direction, even in the case of hydrostatic treatment, the electrode current collecting tab junction region In the non-formation area) can be prevented.

3 is a cross-sectional schematic diagram illustrating a pre-solid battery according to one embodiment.

The entire solid-state cell 1 according to one embodiment has a second electrode layer (cathode layer) 5 and a first electrode collector (anode collector) (cathode collector) 5 on a second electrode current collector The solid electrolyte layer 4 is disposed between the first electrode layer (anode layer) 3 and the second electrode layer (cathode layer) 5, including the first electrode layer (anode layer) have. The same explanation is applied to the second electrode collector (negative electrode collector), the second electrode layer (negative electrode layer), the first electrode collector (positive electrode collector), the first electrode layer (positive electrode layer), and the solid electrolyte layer .

[Method of Manufacturing Lithium Ion Secondary Battery]

According to another aspect of the present invention, there is provided a method of manufacturing a secondary battery, comprising: coating an electrode coating solution containing a first electrode active material or a second electrode active material on a surface of a first electrode current collector and a second electrode current collector, Forming an electrode layer non-formation region including an electrode current collecting tab junction region in each of the electrode layers; Forming a first electrode structure and a second electrode structure by bonding an electrode current collecting tab to the electrode current collecting tab junction region; And disposing an electrolyte layer between the first electrode structure and the second electrode structure and surrounding the electrolyte layer with an external body and integrating the electrolyte layer by pressure treatment to manufacture a secondary battery.

&Lt; Formation of a first electrode layer, a second electrode layer, and an electrode layer non-formation region including an electrode current collecting tab junction region in these electrode layers,

The first electrode layer and the second electrode layer may be a cathode layer or a cathode layer, respectively. Hereinafter, the step of forming the anode layer and the anode layer non-formation region including the anode current collecting tab junction region in the anode layer will be described as a convenience for the first electrode layer as the anode layer. However, the process described below can also be applied to the step of forming the negative electrode layer and the negative electrode layer non-forming region including the negative electrode collector tap junction region in the negative electrode layer, using the second electrode layer as the negative electrode layer.

First, a positive electrode coating liquid is prepared in which a positive electrode active material, a solid electrolyte, and a binder are added in advance as an electrode coating liquid. As the solvent of the anode coating solution, a non-polar solvent is selected. Specific examples thereof include aromatic hydrocarbons such as toluene, xylene, and ethylbenzene, and aliphatic hydrocarbons such as pentane, hexane, and heptane.

The obtained positive electrode coating solution is coated on the surface of the positive electrode current collector and dried to remove the solvent to form the positive electrode layer. The thickness of the anode layer may be from 150 탆 to 350 탆. The application of the positive electrode coating liquid is performed only in a predetermined positive electrode layer formation region, and the positive electrode coating liquid is not applied to the positive electrode collector tab junction region. As a method for applying the positive electrode coating liquid only to a predetermined positive electrode layer formation region, for example, a method of masking the portion corresponding to the positive electrode tab junction region with a metal masking having a notch and then applying the positive electrode coating liquid using screen printing Method, and a method of applying using a die coater or a doctor blade. As a result, the anode layer non-formation region including the anode current collecting tab junction region can be formed simultaneously with the formation of the anode layer.

&Lt; Manufacturing steps of the first electrode structure and the second electrode structure >

The first electrode structure or the positive electrode structure can be manufactured by overlapping one end of the positive electrode current collecting tab in the positive electrode current collecting tab junction region and placing the other end out of the current collector and bonding the positive electrode current collecting tab junction region and the positive electrode current collecting tab . The bonding area may be from 0.15 cm ² to 1.00 cm ² , for example from 0.20 cm ² to 0.25 cm ² . Resistance welding or ultrasonic welding can be applied as a bonding method. After the joining, the overlapped portion (joining portion) with the anode current collecting tab junction region of the anode current collecting tab is supported by the anode layer in two or more directions parallel to the plane direction of the current collector. Therefore, the positive electrode current collecting tab junction region may not be broken even if it is pressed in the post-process.

The manufacturing method may be applied to the second electrode structure or the cathode structure. In the case of manufacturing the negative electrode structure, the negative electrode active material and the binder are added to a polar solvent such as N'-methylpyrrolidone to prepare a negative electrode coating liquid, and the negative electrode active material and the binder are applied to a predetermined region of the negative electrode collector, Regions can be formed. The forming method is the same as the forming method of the positive electrode layer or the positive electrode current collecting tab junction region.

<Manufacturing Step of Secondary Battery>

(Electrolyte layer production process)

When a solid electrolyte layer is produced using a solid electrolyte, a predetermined solid electrolyte and a binder are mixed with an aromatic hydrocarbon such as xylene, toluene, or ethylbenzene, or an aliphatic hydrocarbon such as pentane, hexane, or heptane And then added to a non-polar solvent to prepare a solid electrolyte coating solution. The obtained solid electrolyte coating solution may be coated on the cathode layer side of the second electrode structure or the cathode structure, dried, and the solvent removed to prepare a solid electrolyte layer. The thickness of the solid electrolyte layer may be 75 탆 to 200 탆.

As another method for producing the electrolyte layer, it can be directly formed on a film, dried and then peeled off to form a solid electrolyte single film.

(Assembly process)

In the assembling process, a cell constituted by the first electrode structure or the anode structure, the electrolyte layer, and the second electrode structure or the cathode structure is partially or wholly formed on the first electrode current collecting tab or a part of the positive electrode current collecting tab and the second electrode And a part of the current collecting tab or a part of the negative current collecting tab is exposed. As an example of the enclosing method, the cell is contained in an external body formed in a bag shape, and after the vacuum degassing, the opening is sealed by thermocompression bonding. In the case of molding a bag-like outer body, it is possible to thermally press-fit the folded end portion of the sheet-like outer body into two, or to superimpose two sheet-shaped outer bodies to thermally press the three sides.

Since the cell used in the present invention has no protruding portion, it is possible to suppress the usage amount of the external body necessary for enclosing the cell. Thus, the energy density of the secondary battery, for example, the lithium ion secondary battery, can be improved. In addition, the manufacturing cost can be reduced.

The cells enclosed in the outer casing integrate all the structures by the pressure treatment. The pressing treatment may be performed at a pressure of 294 MPa to 980 MPa for 30 seconds to 20 minutes. For example, the pressing treatment may be performed at a pressure of 490 MPa to 980 MPa for 5 minutes to 10 minutes. The electrode current collecting tab junction region is supported by two or more directions parallel to the surface direction of the current collector by the electrode layer forming region. As a result, the electrode current collecting tab junction region is not damaged even if the pressing is performed under the above-described pressure processing conditions. Therefore, the manufacturing efficiency of the secondary battery is good. When the pressurizing treatment condition is out of the lower limit of the above range, the pressurization can not be sufficiently performed, and the bonding between the particles can not be sufficiently obtained. Therefore, excellent battery characteristics can not be obtained. Further, when the pressurizing treatment condition is out of the upper limit of the above range, the improvement of the additional electrode density can not be obtained. In addition, equipment costs can be added.

As the pressing means, an hydrostatic pressing machine can be used. When the hydrostatic pressure treatment is applied, even if an electrode having a small area difference between the first electrode layer or the anode layer and the second electrode layer or the cathode layer is used, The components of each of the electrode layers and the solid electrolyte layer can be compacted homogeneously at a high pressure. Thus, the energy density of the secondary battery can be improved. The effect of preventing the electrode current collecting tab breakage of the present invention can be exerted particularly in the case of hydrostatic pressure treatment.

The present invention will be described in more detail by way of the following examples and comparative examples. However, the examples are for illustrating the present invention, and the scope of the present invention is not limited thereto.

[Example]

(Production of second electrode structure or cathode structure)

Graphite powder (vacuum drying at 80 캜 for 24 hours) as an anode active material and acid-modified PVdF as a binder were weighed at a ratio of 96.5: 3.5% by weight. The above materials and an appropriate amount of NMP were put into a revolving mixer, stirred at 3000 rpm for 3 minutes, and then defoamed for 1 minute to prepare a negative electrode layer coating solution.

12 cm x 18 cm as the negative electrode collector, and 12 mu m-thick copper foil current collector were prepared. The negative electrode layer coating liquid was coated on the copper foil current collector using the blades. A mask having a notch was placed on the surface of the current collector so that one end of the negative current collecting tab junction region of 0.8 cm x 1 cm could be formed at a position overlapping one end of the current collector. As a result, the negative electrode coating solution was not applied to the notch portion. The thickness (gap) of the negative electrode layer coating liquid on the copper foil collector was about 150 mu m.

The negative electrode collector coated with the negative electrode layer coating solution was placed in a drier heated at 80 캜 and dried for 20 minutes. As a result, the negative electrode layer and the negative electrode current collecting tab junction region were formed on the negative electrode current collector. The cathode current collecting tab junction regions were formed in the state of being supported in three directions parallel to the surface direction of the current collector by the cathode layer forming region of the current collector. The negative electrode current collector was rolled using a roll press machine having a roll gap of 10 mu m. A negative electrode current collecting tab of 0.5 cm x 3 cm was bonded to the negative current collecting tab junction region by ultrasonic welding. As a result, a negative electrode structure joined with the negative electrode current collecting tab was produced. The thickness of the obtained negative electrode structure was about 100 mu m. The joint portions of the negative electrode current collecting tabs were supported by the negative electrode layer in three directions parallel to the surface direction. The negative electrode structure after rolling was also subjected to vacuum heating at 100 DEG C for 12 hours.

(Production of first electrode structure or anode structure)

LiNiCoAlO ₂ ternary phase powder, and a sulfide-based solid electrolyte as Li ₂ SP ₂ S ₅ 60 a vapor-grown carbon fiber powder (80: 20 mol%) as an anode layer of conductive material (conductive material) as a positive electrode active material: 35: 5 parts by weight % Ratio and mixed using a planetary mixer.

A xylene solution in which a styrene thermoplastic elastomer as a positive electrode layer binder was dissolved was added to the mixed powder so that the styrene thermoplastic elastomer was 1.0% by weight based on the total weight of the mixed powder to prepare a primary mixture. Further, dehydrated xylene for adjusting the viscosity was added in an appropriate amount to the primary mixture to produce a secondary mixture. Further, in order to improve the dispersibility of the mixed powder, a zirconia ball having a diameter of 5 mm was charged into the secondary mixture so that the space, the mixed powder, and the zirconia balls each occupied 1/3 of the total volume of the kneading container. The resulting tertiary mixture was added to a planetary mixer and stirred at 3000 rpm for 3 minutes to produce a cathode layer coating solution.

Next, the positive electrode current collector was placed on a tabletop screen printer. A metal mask having a notch structure with a thickness of 150 mu m was formed on the surface of the positive electrode current collector so that one end of the positive electrode current collecting tab junction region of 0.6 cm x 0.8 cm overlapped with one end of the current collector, The coating solution was applied on the positive electrode current collector. Thereafter, the positive electrode collector coated with the positive electrode layer coating liquid was dried on a hot plate at 40 占 폚 for 10 minutes, followed by vacuum drying at 40 占 폚 for 12 hours. As a result, a positive electrode layer and a positive electrode collector tab junction region were formed. The positive electrode collector tab junction region was formed in a state in which it was supported in three directions parallel to the surface direction by the anode layer forming region of the current collector. A positive current collecting tab of 0.5 cm x 3 cm was bonded to the positive electrode collecting tab junction region by ultrasonic welding. The total thickness of the positive electrode collector and the positive electrode layer after drying was about 165 mu m. The joint portions of the positive electrode current collecting tabs were supported in three directions parallel to the surface direction by the anode layer.

(Formation of electrolyte layer)

A sulfide solid electrolyte was prepared by mixing a xylene solution of a styrene type thermoplastic elastomer (electrolyte binder) in an amorphous powder of Li ₂ SP ₂ S ₅ (80:20 mol%) and a styrene type thermoplastic elastomer in an amount of 1 wt% based on the weight of the solid electrolyte powder % Of deionized water to adjust the viscosity of the mixed powder to adjust the viscosity of the mixed powder to prepare a secondary mixed solution. The zirconia balls were charged into the secondary mixture so that the space, the mixed powder, and the zirconia balls each occupied 1/3 of the total volume of the kneading vessel, and the resulting tertiary mixture was introduced into the planetary mixer, Followed by stirring to prepare an electrolyte layer coating solution.

The negative electrode collector was placed on a tabletop screen printer, and the electrolyte layer coating liquid was applied on the negative electrode structure using a metal mask having a thickness of 100 mu m. A metal screen having a notch at the same position as the mask used for forming the cathode structure was used. Thereafter, the sheet coated with the electrolyte layer coating solution was dried on a hot plate at 40 占 폚 for 10 minutes, followed by vacuum drying at 40 占 폚 for 12 hours. Thus, an electrolyte layer was formed on the cathode structure. The thickness of the electrolyte layer after drying was about 130 mu m.

(Production of Secondary Battery)

The second electrode structure or cathode structure, the electrolyte layer, and the first electrode structure or the anode structure are each punched with a Thomson blade, and the second electrode structure or the cathode structure, the electrolyte layer, and the first electrode structure or the anode structure are stacked Aluminum laminate film, vacuum degassed and packed by heat sealing. Thereafter, the battery was pressurized and pressurized at 490 MPa for 10 minutes by using a hydrostatic press machine to produce a lithium ion secondary battery having a structure as shown in FIG. 1B.

As shown in FIG. 1B, in the above structure, the joints of the electrode tabs are subjected to a hydrostatic pressure treatment, and the rupture of the first electrode current collecting tab junction region or the second electrode current collecting tab junction region or the negative electrode current collecting tab junction region, Was confirmed, but no breakage was recognized.

[Comparative Example]

A first electrode layer or a positive electrode layer, a second electrode layer or a negative electrode layer, and a solid electrolyte layer were formed using a metal screen having no notch with the same raw material as that of Example 1, An electrode structure or a cathode structure, and a second electrode structure or a cathode structure were prepared, and a solid electrolyte layer was also prepared. The first electrode structure or the positive electrode structure and the second electrode structure or the negative electrode structure produced a lithium ion secondary battery having a structure as shown in FIG. 2B.

As shown in Fig. 2B, the junction regions of the electrode current collectors and the electrode current collecting tabs protrude from the electrode layer forming regions, and the electrode current collecting tab junction regions are formed in one direction parallel to the surface direction .

The first electrode layer or the positive electrode layer, the solid electrolyte layer, and the second electrode layer or the negative electrode layer are laminated and enclosed in an external body. Thereafter, it was pressurized at 490 MPa for 10 minutes by using an hydrostatic press. However, at the time of pressurization, the electrode current collecting tab junction region was broken together with the positive electrode and the negative electrode. Therefore, the ruptured electrode current collecting tab was re-applied to produce a lithium ion secondary battery.

[Evaluation of energy density]

The weight and volume of the external body were measured for each of the lithium ion secondary batteries of Examples and Comparative Examples, and the energy density was measured and evaluated by the following method. That is, the discharge capacity and the average discharge voltage were measured by a conventionally known method, and the weight and volume of the batteries were measured, and the weight energy density and the volume energy density were calculated based on the measured values. The evaluation results are shown in Table 1 below.

Example Comparative Example Weight of outer body (g) 3.340 3.712 Weight Energy Density (Wh / kg) 173 156 The volume of the outer body (cm ³ ) 1.728 1.872 Volumetric energy density (Wh / L) 343 333

As shown in Table 1, the weight energy density of the examples was 173 Wh / kg and the volume energy density was 343 Wh / L. The weight energy density of the comparative example was 156 Wh / kg, and the volume energy density was 333 Wh / L. Meanwhile, the weight energy density of the lithium ion secondary battery in another example of the present invention produced by the same method as the example was 175 Wh / kg. Therefore, it can be confirmed that the weight energy density and the volume energy density of the examples are improved as compared with the weight energy density and the volume energy density of the comparative example.

1: Whole solid battery 2: First electrode collector (anode collector)
3: First electrode layer (anode layer) 4: Solid electrolyte layer
5: Second electrode layer (cathode layer) 6: Second electrode collector (cathode collector)
100, 200: electrode structure 101, 201: electrode layer
102 (103), 202 (203): electrode current collecting tab junction region (electrode current collector)
104, 204: electrode current collecting tabs 105, 205: sealant 106, 206:

Claims (21)

A secondary battery comprising an electrode layer forming region and an electrode layer non-forming region on a surface of an electrode collector of each of the first electrode structure and the second electrode structure,
And an electrode layer non-formation region including an electrode current collecting tab junction region in the electrode layer formation region,
Wherein the first electrode structure, the second electrode structure, and an electrolyte layer disposed between the first electrode structure and the second electrode structure are enclosed by an external body and are integrated by pressure treatment. The secondary battery according to claim 1, wherein the electrode current collecting tab junction region is located at an outermost portion of the electrode layer forming region. The secondary battery according to claim 1, wherein the electrode current collecting tab junction region has a circular or polygonal shape. The secondary battery according to claim 1, wherein an outer edge portion of the electrode current collecting tab junction region is supported by the electrode layer forming region in two or more directions parallel to the surface direction. The secondary battery according to claim 1, wherein the electrode current collecting tab junction region has a quadrangular shape and the outer edge portion of the electrode current collecting tab junction region is supported by the electrode layer forming region in three directions parallel to the surface direction. The secondary battery according to claim 1, further comprising an electrode current collecting tab joined to the electrode current collecting tab junction region and having one end protruded from the electrode current collector. The secondary battery according to claim 6, wherein the electrode current collecting tabs are supported by an electrode layer formed in the electrode layer forming region in two or more directions parallel to the surface direction. The secondary battery according to claim 1, wherein an area of the electrode current collecting tab junction region is 0.8% to 1.3% based on a total area of the electrode current collector. The secondary battery according to claim 1, wherein the secondary battery has no protruding portion. The secondary battery according to claim 1, wherein the electrolyte layer comprises a solid electrolyte. The secondary battery according to claim 10, wherein the solid electrolyte comprises a sulfide-based compound. 12. The secondary battery according to claim 11, wherein the sulfide-based compound comprises Li ₇ P ₃ S ₁₁ , Li ₃ PS ₄ , Li ₇ PS ₆ , or Li ₆ PS ₅ Cl. The secondary battery according to claim 11, wherein the sulfide compound has an average particle diameter of 0.1 to 100 탆. The secondary battery according to claim 11, wherein the sulfide compound has a specific surface area of at least 0.1 m ² / g or more. The secondary battery according to claim 1, wherein the casing is formed of a material having flexibility, liquid tightness, and airtightness. The secondary battery according to claim 1, wherein the casing is formed of a material in which a film of a thermo-compressible resin is formed on a surface of a metal material. The secondary battery according to claim 1, wherein the pressure treatment is hydrostatic pressure treatment. An electrode coating liquid containing a first electrode active material or a second electrode active material is coated on the surfaces of the first electrode current collector and the second electrode current collector to form first electrode layers and second electrode layers, Forming an electrode layer non-formation region including a junction region;
Forming a first electrode structure and a second electrode structure by bonding an electrode current collecting tab to the electrode current collecting tab junction region; And
And disposing an electrolyte layer between the first electrode structure and the second electrode structure and enclosing the electrolyte layer with an external body and integrating the electrolyte layer by pressure treatment to manufacture a secondary battery.       19. The method of manufacturing a secondary battery according to claim 18, wherein the electrode current collecting tab junction regions are formed in the electrode layer non-formation regions in the first electrode layer and the second electrode layer, respectively. The method of manufacturing a secondary battery according to claim 18, wherein the pressure treatment is a hydrostatic pressure treatment. The method for producing a secondary battery according to claim 18, wherein the pressure treatment is performed at a pressure of 294 MPa to 980 MPa for 30 seconds to 20 minutes.

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