KR20220057166A - Bipolar all-solid-state battery comprising a porous supporting layer - Google Patents

Abstract

The present invention relates to a bipolar all-solid-state battery including a porous support layer and a method for manufacturing the same, and specifically, to a bipolar all-solid-state battery in which two or more unit cells including a positive electrode, a solid electrolyte layer, and a negative electrode are connected in series, a porous support layer is provided in the center of a part in which the unit cells are connected in series, a negative electrode of one unit cell is disposed on one side of the porous support layer, and a positive electrode of another unit cell is disposed on an opposite side.

Description

Bipolar all-solid-state battery comprising a porous supporting layer

The present invention relates to a bipolar all-solid-state battery including a porous support layer. Specifically, two or more unit cells including a positive electrode, a solid electrolyte layer, and a negative electrode are connected in series, and a portion where the unit cells are connected in series is provided with a porous support layer in the center, and one surface of the porous support layer is one unit It relates to a bipolar all-solid-state battery in which the negative electrode of the cell and the positive electrode of another unit cell are disposed on the opposite side thereof.

The bipolar battery has the advantages of high energy density, stable performance, and low internal resistance by minimizing the volume of the case. Such a bipolar battery generally has a bipolar electrode including a bipolar electrode layer and a bi-plate for serially connecting one unit cell and the adjacent unit cells. The bi-plate may be made of a material having sufficient conductivity to transmit current between the unit cells, chemically stable in the battery, and excellent in contact with the electrode. These bi-plates are easily corroded by the high dielectric electrolyte mainly used in lithium secondary batteries, and the corroded bi-plates deteriorate the electrolyte sealability and insulation between unit cells, and cause internal short circuits, which ultimately lowers the safety of the battery. causes

In order to solve the above problems, a bipolar all-solid-state battery that does not use an electrolyte has been proposed as an alternative. The bipolar all-solid-state battery has a solid electrolyte layer containing a solid electrolyte, unlike a conventional secondary battery, and the solid electrolyte layer is disposed between the positive electrode and the negative electrode to serve as a separator.

Since the all-solid-state battery uses a solid electrolyte instead of the liquid electrolyte used in conventional batteries, there is no evaporation of the electrolyte due to temperature change or leakage due to an external shock, so it is safe from explosion and fire. Since the contact area between the solid electrolyte and the positive electrode or the negative electrode is limited, there is a disadvantage in that it is not easy to form an interface between the positive electrode and the negative electrode and the solid electrolyte layer. As described above, when the contact surface between the positive electrode and the negative electrode and the solid electrolyte layer is small, the interface resistance is reduced by pressing the unit cell including the solid electrolyte.

Meanwhile, in order to increase the density and capacity of the bipolar all-solid-state battery and increase the lifespan, the bipolar all-solid-state battery may be manufactured using lithium. When lithium is used, lithium dendrites are formed during the charging/discharging process to damage the separator (solid electrolyte layer), or the lithium dendrites come into contact with the positive electrode to cause a short circuit in the unit cell. In particular, when the bipolar all-solid-state battery is pressurized, the positive electrode, the solid electrolyte layer, and the negative electrode come close to each other due to the growth of the lithium dendrite, resulting in damage to the solid electrolyte layer or a short circuit due to the reaction between the lithium dendrite and the positive electrode. .

1 is a perspective view of a bipolar all-solid-state battery according to the prior art before charging and discharging, and FIG. 2 is a perspective view after charging and discharging of a bipolar all-solid-state battery according to the prior art.

The bipolar all-solid-state battery 10 according to the prior art includes a first positive electrode 110 including a first positive electrode active material 111 and a first positive electrode current collector 112 , a first solid electrolyte layer 120 , and a first negative electrode. The first unit cell 100 including the first negative electrode 130 including the active material 131 and the first negative electrode current collector 132, the second positive electrode active material 211, and the second positive electrode current collector 212 are formed. A second unit cell including a second anode 210 including a second anode 210 , a second solid electrolyte layer 220 , a second cathode active material 231 , and a second cathode 230 including a second cathode current collector 232 . 200 and a bipolar electrode 300 for connecting the first unit cell 100 and the second unit cell 200 in series.

At this time, the first positive electrode active material 111, the first negative electrode active material 131, the second positive electrode active material 211, and the second negative electrode active material 231 are different from FIGS. 1 and 2 in the first positive electrode current collector ( 112), the first negative electrode current collector 132, the second positive electrode current collector 212, and the second negative electrode current collector 132 may be coated on only one surface, or a separate electrode active material may not be applied.

The interface resistance between the first anode 110 , the first solid electrolyte layer 120 , the first cathode 130 and the second anode 210 , the second solid electrolyte layer 220 , and the second cathode 230 . In order to reduce , the bipolar all-solid-state battery 10 according to the prior art is pressurized by the pressing force F1 in the y-axis direction from the jig during charging and discharging.

However, in the bipolar all-solid-state battery 10 , the lithium layer 400 generated when the first unit cell 100 and the second unit cell 200 are charged and discharged is the first cathode 130 and/or the second unit cell 200 . It is inserted into the negative electrode 230 to expand the active material, or lithium is deposited on the first negative electrode 130 and/or the second negative electrode 230 to increase the thickness of the bipolar all-solid-state battery 10 .

When the thickness of the bipolar all-solid-state battery 10 increases, the internal pressure F2 of the bipolar all-solid-state battery 10 increases and is applied to the first unit cell 100 and the second unit cell 200 . The lowering pressing force F1 also increases. Typically, the pressing force F1 is generated by the jig, and the jig occupies a certain position, because the internal volume increases.

As the lithium layer 400 formed due to the initial charge and discharge increases, the reaction force between the first solid electrolyte layer 120 and the second solid electrolyte layer 220 and the lithium layer 400 increases, and the lithium layer ( The lithium metal of 400) flows into the interior through defects of the first solid electrolyte layer 120 and the second solid electrolyte layer 220, thereby increasing the possibility of causing a short circuit of the bipolar all-solid-state battery 10.

Also, when the pressing force F1 is increased, the positions and shapes of the first unit cell 100 and the second unit cell 200 in the bipolar all-solid-state battery 10 may be deformed. When the shape of the bipolar all-solid-state battery 10 or the positions of the first unit cell 100 and the second unit cell 200 is changed, the pressing force F1 is applied to the first unit cell 100 and the second unit cell ( 200) is not evenly applied, so some may not be pressurized or some may be overly pressurized.

Patent Document 1 relates to an all-solid thin film stack battery, and mentions a case where a plurality of power generating elements are connected in series, but unlike the bipolar battery of the present invention, the power generating elements are connected in series through an electrode terminal, , the internal stress of the thin film stacked battery is relieved, but the density of the battery is not improved.

As described above, it is necessary to prevent damage to the solid electrolyte layer due to lithium dendrites while reducing the internal stress of the bipolar all-solid-state battery having excellent performance compared to the density, but a clear solution has not been proposed.

Japanese Laid-Open Patent Publication No. 2004-273436 (2004.09.30) ('Patent Document 1')

An object of the present invention is to solve the above problems, and to prevent damage to the solid electrolyte layer due to the formation of lithium dendrites and short circuit of the unit cells due to the lithium dendrites coming into contact with the positive electrode.

Another object of the present invention is to reduce the internal stress of the bipolar all-solid-state battery and improve the ionic conductivity to improve the lifespan.

In order to achieve the above object, the bipolar all-solid-state battery according to the present invention is an all-solid-state battery in which two or more unit cells including a positive electrode, a solid electrolyte layer, and a negative electrode are connected in series, wherein the unit cells are connected in series A porous support layer may be provided in the center, the negative electrode of one unit cell may be disposed on one surface of the porous support layer, and the positive electrode of another unit cell may be disposed on an opposite surface thereof.

In this case, the negative electrode may be a current collector without a lithium metal or an active material layer.

In addition, the porous support layer may include at least one sheet or nonwoven fabric made of one or more selected from the group consisting of an olefin-based porous substrate and glass fiber or polyethylene.

The porous support layer may be one in which the olefin-based porous substrate or sheet or nonwoven fabric is laminated in one or more layers.

In addition, when the porous support layer has two or more layers, each layer of the porous support layer may be made of a different material, or each layer of the porous support layer may be made of the same material.

The thickness of the porous support layer is reduced when pressure is applied, and the thickness is restored when the pressure is released, thereby controlling the stress inside the all-solid-state battery.

At this time, the pressure may be generated as lithium ions of the positive electrode move to the negative electrode by charging and are deposited between the negative electrode and the solid electrolyte layer.

The porous support layer may control stress according to a thickness change due to lithium deposition.

The porous support layer may control the stress in proportion to the thickness and porosity of the porous support layer.

The porous support layer may have a thickness of 20 μm to 50 μm.

The positive electrode may include a positive electrode current collector and a positive electrode active material applied to one surface of the positive electrode current collector.

The positive electrode active material may face the solid electrolyte layer, and the positive electrode current collector may face the porous support layer.

The negative electrode of one unit cell disposed on one surface of the porous support layer may be lithium metal without a separate active material layer, and the positive electrode of another unit cell disposed on the opposite surface of the porous support layer may be a positive electrode current collector.

The unit cell may be accommodated in a pouch-type battery case.

The unit cell may be pressurized by a jig when in use.

The present invention may be a battery module or battery pack including the above-mentioned bipolar all-solid-state battery. It may also be a device equipped with the bipolar all-solid-state battery.

In the present invention, one or two or more components that do not conflict among the above components may be selected and combined.

As described above, the bipolar all-solid-state battery according to the present invention reduces the stress generated in the bipolar all-solid-state battery according to the formation of the lithium layer, so that the solid electrolyte layer is damaged or the lithium dendrites of the positive electrode and the lithium layer are damaged. It can prevent the reaction, thereby reducing the cell short inside the bipolar all-solid-state battery.

In addition, the bipolar all-solid-state battery uses only a negative current collector as a negative electrode, uses only a positive electrode current collector and a positive active material coated on one side of the positive electrode as a positive electrode, and connects the unit cells made of these in series through a porous support layer. and improve performance.

In addition, by maintaining a constant pressure applied to the unit cell inside the bipolar all-solid-state battery, damage to the unit cell and the ionic conductivity of the unit cell are improved, thereby improving the battery life.

1 is a perspective view before charging and discharging of a bipolar all-solid-state battery according to the prior art.
2 is a perspective view after charging and discharging of a bipolar all-solid-state battery according to the prior art.
3 is a perspective view before charging and discharging of the bipolar all-solid-state battery according to the present invention.
4 is a perspective view after charging and discharging of the bipolar all-solid-state battery according to the present invention.
5 is a cross-sectional view of the all-solid-state battery used in Experimental Example 2 according to the present invention.

Hereinafter, embodiments in which those of ordinary skill in the art to which the present invention pertains can easily practice the present invention will be described in detail with reference to the accompanying drawings. However, when it is determined that a detailed description of a related well-known function or configuration may unnecessarily obscure the gist of the present invention in describing the operating principle of the preferred embodiment of the present invention in detail, the detailed description thereof will be omitted.

In addition, the same reference numerals are used throughout the drawings for parts having similar functions and functions. Throughout the specification, when a part is said to be connected to another part, it includes not only a case in which it is directly connected, but also a case in which it is indirectly connected with another element interposed therebetween. In addition, the inclusion of any component does not exclude other components unless otherwise stated, but means that other components may be further included.

In addition, descriptions that limit or add elements may be applied to all inventions unless there are special limitations, and are not limited to specific inventions.

Also, throughout the description and claims of the present application, the singular includes the plural unless otherwise indicated.

Also, throughout the description and claims herein, "or" is intended to include "and" unless stated otherwise. Therefore, "comprising A or B" means all three cases including A, including B, or including A and B.

Also, all numerical ranges include the values at both ends and all intermediate values therebetween, unless expressly stated otherwise.

In the bipolar all-solid-state battery according to the present invention, two or more unit cells including a positive electrode, a solid electrolyte layer, and a negative electrode are connected in series, and a portion where the unit cells are connected in series is provided with a porous support layer in the center, and the porous support layer One surface of is characterized in that the negative electrode of one unit cell is disposed, and the positive electrode of the other unit cell is disposed on the opposite surface.

The bipolar all-solid-state battery according to the present invention will be described with reference to the perspective views of FIGS. 3 and 4 . 3 is a perspective view before charging and discharging of the bipolar all-solid-state battery 1000 according to the present invention, and FIG. 4 is a perspective view after charging and discharging of the bipolar all-solid-state battery 1000 according to the present invention.

3 and 4, the unit cell is illustrated as the first unit cell 1100 and the second unit cell 1200 for convenience of explanation, but the unit cell is the first unit cell 1100 and the second unit cell. (1200) may include a plurality of.

The bipolar all-solid-state battery 1000 according to the present invention includes a first unit cell 1100 and a second unit cell 1200 . The first unit cell 1100 includes a first positive electrode 1110 including a first positive electrode active material 1111 and a first positive electrode current collector 1112 , a first solid electrolyte layer 1120 , and a first negative electrode current collector. Consists of a first negative electrode 1130 including 1132, and the second unit cell 1200 is a second positive electrode 1210 including a second positive electrode active material 1211 and a second positive electrode current collector 1212 , a second solid electrolyte layer 1220 , and a second cathode 1230 including a second cathode current collector 1232 . A porous support layer 1300 for connecting the unit cells in series is disposed between the first unit cell 1100 and the second unit cell 1200 . On one surface of the porous support layer 1300, the first cathode 1130 of the first unit cell 1100 is disposed, and on the other surface of the porous support layer 1300, that is, on the opposite surface of the first cathode 1130, a second A second anode 1210 of the unit cell 1200 is disposed.

The first positive electrode 1110 is, for example, by applying a positive electrode mixture in which a positive electrode active material composed of positive electrode active material particles, a conductive material and a binder are mixed on a first positive electrode current collector 1112 to form a first positive electrode active material 1111 It may be manufactured by a method of forming, and if necessary, a filler may be further added to the positive electrode mixture.

The first positive electrode current collector 1112 is generally manufactured to have a thickness of 3 μm to 500 μm, and is not particularly limited as long as it has high conductivity without causing chemical change in the battery. For example, stainless steel , aluminum, nickel, titanium, and carbon, nickel, titanium or silver on the surface of aluminum or stainless steel may be used, and specifically aluminum may be used. The current collector may increase the adhesion of the positive electrode active material by forming fine irregularities on the surface thereof, and various forms such as a film, sheet, foil, net, porous body, foam body, and non-woven body are possible.

The positive electrode active material contained in the first positive electrode active material 1111, for example, in addition to the positive electrode active material particles, lithium nickel oxide (LiNiO ₂ ) A layered compound such as or a compound substituted with one or more transition metals; Lithium manganese oxides such as Formula Li _1+x Mn _2-x O ₄ (where x is 0 to 0.33), LiMnO ₃ , LiMn ₂ O ₃ , and LiMnO ₂ ; lithium copper oxide (Li ₂ CuO ₂ ); vanadium oxides such as LiV ₃ O ₈ , LiV ₃ O ₄ , V ₂ O ₅ , and Cu ₂ V ₂ O ₇ ; Ni site-type lithium nickel oxide represented by the formula LiNi _1-x M _x O ₂ (wherein M = Co, Mn, Al, Cu, Fe, Mg, B or Ga, and x = 0.01 to 0.3); Formula LiMn _2-x M _x O ₂ (wherein M = Co, Ni, Fe, Cr, Zn or Ta and x = 0.01 to 0.1) or Li ₂ Mn ₃ MO ₈ (where M = Fe, Co, lithium manganese composite oxide represented by Ni, Cu or Zn; LiMn ₂ O ₄ in which a part of Li in the formula is substituted with an alkaline earth metal ion; a disulfide compound; It may be composed of Fe ₂ (MoO ₄ ) ₃ and the like, but is not limited thereto.

However, the positive active material used in the present invention preferably uses or includes a metal oxide containing lithium in order to deposit lithium on the first negative electrode 1130 .

The conductive material is typically added in an amount of 0.1 to 30% by weight based on the total weight of the mixture including the positive electrode active material. Such a conductive material is not particularly limited as long as it has conductivity without causing a chemical change in the battery. For example, graphite such as natural graphite or artificial graphite; carbon black, such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, and summer black; conductive fibers such as carbon fibers and metal fibers; metal powders such as carbon fluoride, aluminum, and nickel powder; conductive whiskeys such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives may be used.

The binder included in the first positive electrode 1110 is a component that assists in bonding between the active material and the conductive material and bonding to the current collector, and is typically 0.1 to 30% by weight based on the total weight of the mixture including the positive electrode active material. is added Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene , polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, fluororubber, and various copolymers.

The first positive electrode 1110 may have a shape in which a first positive electrode active material 1111 is formed on at least one surface of the first positive electrode current collector 1112 . At this time, when the first positive electrode 1110 is located on the outermost side of the bipolar all-solid-state battery 1000, the first positive electrode 1110 is the first positive electrode active material ( 1111) may be applied. In addition, when the first positive electrode 1110 faces another unit cell of the bipolar all-solid-state battery 1000 , the first positive electrode 1110 is formed on only one surface of the first positive electrode current collector 1112 . A cathode active material 1111 may be coated.

The second anode 1210 may be formed in the same manner as the first anode 1110 . However, the second positive electrode 1210 faces the unit cell of the bipolar all-solid-state battery 1000 and the second positive electrode active material 1211 only on one surface of the second positive electrode current collector 1212 of the second positive electrode 1210 . ) has only the form in which it is formed.

The second positive electrode active material 1211 of the second positive electrode 1210 disposed on the other surface of the porous support layer 1300 faces the second solid electrolyte layer 1220, and the second positive electrode current collector 1212 is the The porous support layer 1300 faces the porous support layer 1300 so that the unit cells of the bipolar all-solid-state battery 1000 can be connected in series.

For the first solid electrolyte layer 1120 and the second solid electrolyte layer 1220 , an organic solid electrolyte or an inorganic solid electrolyte may be used, but is not limited thereto.

Examples of the organic solid electrolyte include polyethylene derivatives, polyethylene oxide derivatives, polypropylene oxide derivatives, phosphoric acid ester polymers, poly agitation lysine, polyester sulfide, polyvinyl alcohol, polyvinylidene fluoride, ions A polymer containing a sexually dissociating group or the like can be used.

Examples of the inorganic solid electrolyte include a sulfide-based solid electrolyte and an oxide-based solid electrolyte.

As the oxide-based solid electrolyte, for example, Li _6.25 La ₃ Zr ₂ A ₁₀ . ₂₅ O ₁₂ , Li ₃ PO ₄ , Li ₃ +xPO ₄ -xN _x (LiPON), Li ₃ N, LiI, Li ₅ NI ₂ , Li ₃ N-LiI-LiOH, LiSiO ₄ , LiSiO ₄ -LiI-LiOH, A nitride, a halide of Li, such as Li ₂ SiS ₃ , Li ₄ SiO ₄ , Li ₄ SiO ₄ -LiI-LiOH, or the like may be used.

The sulfide-based particles are not particularly limited in the present invention, and all known sulfide-based materials used in the field of lithium batteries may be used. As the sulfide-based material, a commercially available one may be purchased and used, or an amorphous sulfide-based material manufactured through a crystallization process may be used. For example, the sulfide-based solid electrolyte may include a crystalline sulfide-based solid electrolyte, an amorphous sulfide-based solid electrolyte, and any one or mixture thereof. Examples of the complex compound that can be used include a sulfur-halogen compound, a sulfur-germanium compound, and a sulfur-silicon sulfide, specifically SiS ₂ , GeS ₂ , B ₂ S ₃ It may include a sulfide such as Li ₃ PO ₄ or halogen, a halogen compound, etc. may be added. Preferably, a sulfide-based electrolyte capable of implementing lithium ion conductivity of 10 ^-4 S/cm or more may be used.

Representatively, Li ₆ PS ₅ Cl (LPSCl), Thio-LISICON (Li _3.25 Ge _0.25 P _0.75 S ₄ ), Li ₂ SP ₂ S ₅ -LiCl, Li ₂ S-SiS ₂ , LiI-Li ₂ S-SiS ₂ , LiI-Li ₂ SP ₂ S ₅ , LiI-Li ₂ SP ₂ O ₅ , LiI-Li ₃ PO ₄ -P ₂ S ₅ , Li ₂ SP ₂ S ₅ , Li ₃ PS ₄ , Li ₇ P ₃ S ₁₁ , LiI-Li ₂ SB ₂ S ₃ , Li ₃ PO ₄ -Li ₂ S-Si ₂ S, Li ₃ PO ₄ -Li ₂ S-SiS ₂ , LiPO ₄ -Li ₂ S-SiS, Li ₁₀ GeP ₂ S ₁₂ , Li _9.54 Si _1.74 P _1.44 S _11.7 Cl _0.3 , Li ₇ P ₃ S ₁₁ , etc.

A coating layer for inducing formation of lithium dendrites may be formed on the first and second cathodes 1130 and 1230 of the first solid electrolyte layer 1120 and the second solid electrolyte layer 1220 .

The coating layer may include a metal to improve electrical conductivity and ionic conductivity. The metal improves the performance of the first negative electrode 1130 or the second negative electrode 1230, and the lithium dendrite forms the coating layer and the first negative electrode current collector 1132 or the coating layer and the second negative electrode current collector ( 1232), as long as it is a metal that can be formed between them, there is no limitation on the type. At this time, since the metal has lithium-friendly properties, lithium dendrites can be induced to be formed between the coating layer and the first negative current collector 1132 or the coating layer and the second negative current collector 1232 . can

At this time, in order to prevent lithium dendrite from growing in the direction of the first solid electrolyte layer 1120 or the second solid electrolyte layer 1220 , the lithium-friendly metal is the coating layer first cathode 1130 or the second It may be disposed on the cathode-facing surface 1230 .

When a lithium-friendly metal is located in the coating layer, lithium plating occurs on the lithium-friendly metal to form lithium nuclei, and lithium dendrites grown in the lithium nuclei grow only in the coating layer.

At least one of a metal and a metal oxide may be selected as the lithium-friendly metal. For example, the metal corresponds to gold (Au), silver (Ag), platinum (Pt), zinc (Zn), silicon (Si) and magnesium (Mg), and the metal oxide is copper oxide as a non-metal; Zinc oxide, cobalt oxide, etc. may be applicable.

The first negative electrode 1130 according to the present invention may consist of only the first negative electrode current collector 1132 .

The first negative current collector 1132 is generally made to have a thickness of 3 μm to 500 μm. The first anode current collector 1132 is not particularly limited as long as it has conductivity without causing a chemical change in the battery, and may be a current collector without lithium metal or a separate anode active material layer. For example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, a surface treatment of copper or stainless steel with carbon, nickel, titanium, silver, etc., an aluminum-cadmium alloy, etc. may be used. In addition, like the first positive electrode current collector 1112 , it is also possible to strengthen the bonding force of the negative electrode active material by forming fine irregularities on the surface, and to be used in various forms such as films, sheets, foils, nets, porous materials, foams, nonwovens, etc. can

The second cathode 1230 may have the same shape as the first cathode 1130 .

The first unit cell 1100 and the second unit cell 1200 have the same shape as described above and are connected in series to obtain the bipolar all-solid-state battery 1000 having a high energy density.

A porous support layer 1300 may be disposed between the first unit cell 1100 and the second unit cell 1200 to connect the unit cells in series.

For the porous support layer 1300 to connect the first unit cell 1100 and the second unit cell 1200 in series, any material having electrical conductivity and ion conductivity may be used. For example, the porous support layer 1300 may include at least one sheet or nonwoven fabric made of one or more selected from the group consisting of an olefin-based porous substrate and glass fiber or polyethylene. In this case, the porous support layer 1300 is preferably a sheet made of at least one selected from the group consisting of an olefin-based porous substrate or glass fiber or polyethylene. In the case of the nonwoven fabric form, the porosity is large, but in order for the porous support layer 1300 to have a certain strength, the nonwoven fabric must be laminated in several layers. because it doesn't

Specifically, the porous support layer 1300 includes a resin such as polyolefin (polyethylene, polypropylene, polybutene, polyvinyl chloride) and mixtures or copolymers thereof, or polyethylene terephthalate, polycycloolefin, polyethersulfone, poly and resins such as amide, polyimide, polyimideamide, polyaramid, polycycloolefin, nylon, polytetrafluoroethylene, and the like. Among them, the polyolefin-based resin is preferable because it can increase the capacity per volume in the bipolar all-solid-state battery 1000 by reducing the thickness.

The porous support layer 1300 has elasticity and is made of a material that can relieve the stress generated inside the bipolar all-solid-state battery 1000, or the bipolar all-solid-state battery 1000 through the pores of the porous support layer 1300. The internal stress can be relieved.

The porous support layer may be one in which the olefin-based porous substrate or sheet or nonwoven fabric is laminated in one or more layers.

When the porous support layer is formed as a multilayer, the range of stress that the porous support layer can relieve may be increased.

When the porous support layer has two or more layers, each layer of the porous support layer may be made of a different material, or each layer of the porous support layer may be made of the same material.

The pore diameter of the porous support layer 1300 is generally 0.01 μm to 10 μm, and the thickness may be generally 20 μm to 50 μm. At this time, the porosity 1300 of the porous support layer may be 30% to 90%.

The porous support layer 1300 controls stress according to a thickness change due to lithium deposition. In order to relieve the stress of the porous support layer 1300 as described above, the elastic range of the porous support layer 1300 should be greater than the deformation range due to the deposited lithium. The elastic range of the porous support layer 1300 is proportional to the thickness and porosity of the porous support layer 1300 .

That is, the elastic range of the porous support layer 1300 may be expressed as follows.

Elastic range of porous support layer = thickness of porous support layer X porosity of porous support layer

At this time, the elastic force of the material itself used as the porous support layer 1300 should be greater than the driving pressure of the jig.

The porous support layer 1300 is disposed between the first negative electrode current collector 1132 of the first unit cell 1100 and the second positive electrode current collector 1212 of the second unit cell 1200, the porous support layer ( 1300 ), the first negative electrode current collector 1132 , and the second positive electrode current collector 1212 may be used as bipolar electrodes of the bipolar all-solid-state battery 1000 . As described above, since the first unit cell 1100, the second unit cell 1200, and the bipolar electrode share a portion with each other, the density of the bipolar all-solid-state battery 1000 can be improved. To this end, the porous support layer 1300 is formed by pressing the first unit cell 1100 and the second unit cell 1200 .

The first unit cell 1100 , the second unit cell 1200 , and the porous support layer 1300 are pressurized with a constant pressing force F1 by a jig, which is even when the bipolar all-solid-state battery 1000 is used. lasts

In the bipolar all-solid-state battery 1000 according to the present invention, a lithium layer 1400 is formed after charging and discharging as shown in FIG. 4 . In the lithium layer 1400, lithium is deposited between the first cathode 1130 or the second cathode 1230 and the first solid electrolyte layer 1120 or the second solid electrolyte layer 1220 by charging and discharging. is formed This is because lithium ions of the first positive electrode 1110 or the second positive electrode 1210 move to the first negative electrode 1130 or the second negative electrode 1230, and the first negative electrode 1130 and the first solid electrolyte layer ( 1120) or between the second cathode 1230 and the second solid electrolyte layer 1220.

The lithium layer 1400 is charged under constant current/constant voltage (CC/CV) conditions, and the pressing force F1 applied to the entire lithium secondary battery at this time depends on the amount of lithium formed in the battery, charge/discharge rate and time, etc. will be different This is because the lithium layer 1400 is formed to generate an internal pressure F2.

In the bipolar all-solid-state battery 1000 according to the present invention, the stress generated by the internal pressure F2 applied by the lithium layer 1400 is resolved through the porous support layer 1300 . The porous support layer 1300 has a constant pressing force F1 over the entire bipolar all-solid-state battery 1000 by reducing the pores in the porous support layer 1300 or changing a shape including a decrease in the thickness of the porous support layer 1300 . ) to be applied.

The pore reduction or shape deformation of the porous support layer 1300 as described above is controlled according to the formation and/or disappearance of the lithium layer 1400 . For example, when the lithium layer 1400 is formed and an internal pressure F2 is generated, pores of the porous support layer 1300 may decrease and the thickness may decrease. In addition, when the lithium layer 1400 disappears, the porous support layer 1300 is restored to its original state to maintain the same thickness (m) before pressurization and thickness (M) after pressurization of the bipolar all-solid-state battery.

The bipolar all-solid-state battery 1000 is formed by accommodating the unit cells in a battery case capable of pressurizing the entire unit cell of the bipolar all-solid-state battery 1000 in order to constantly pressurize the unit cells even during use, or After accommodating the unit cells in the pouch-type battery case, the bipolar all-solid-state battery 1000 may be pressurized from the outside of the pouch-type battery case.

Hereinafter, the present invention will be described through an experimental example in which an experimental example according to the present invention and a comparative example according to the prior art are compared.

(Experimental Example 1) Porous support layer elastic force test

The thickness change of the porous support layer with respect to the jig pressure during driving of the all-solid-state battery and/or the pressure change due to lithium deposited during charging was measured. In this case, as the porous support layer, porous support layer #1 and porous support layer #2 having similar porosity and different thicknesses and porous support layer #3 having different porosity and thickness were used.

Polyethylene was used as the porous support layer.

After the porous support layer was punched to 2.5 cm x 2.5 cm, the all-solid-state battery was sequentially pressurized to 5 MPa, 10 MPa, 15 MPa, and 20 MPa using a jig, and after measuring the thickness change in each step, the following Table 1 shows.

Each porous support layer decreases in thickness as the pressure increases. However, in the case of an ultra-thin porous support layer with a thin thickness, such as porous support layer #1, the thickness change according to pressure was small, and as in porous support layer #3, it was thick and porous with high porosity. The thickness change of the support layer was large according to the pressure. For the porous support layer #1 to porous support layer #3, the deformation of the porous support layer according to the pressure change due to the pressure applied during the evaluation of the all-solid-state battery and the lithium generated during charging was simulated, and the porous support layer was 5 MPa once, twice, 3 times. After pressing times, 5 times, and 10 times, the thickness was measured and shown in Table 2.

At this time, the porous support layer #1 was pressurized to 20 MPa, and the porous support layer #2 was pressurized to 10 MPa, and laminated 1, 2, and 3 sheets, respectively, was used, and the porous support layer #3 The non-pressurized ones and those pressurized at 10 MPa were pressurized 1 time, 2 times, 3 times, 5 times, and 10 times, respectively, at 5 MPa each.

In order to reduce the stress generated in the bipolar all-solid-state battery as desired in the present invention, the deformation range due to pressure must be within the elastic range of the porous support layer. As can be seen in Table 2, the porous support layer according to the present invention has a thin film type, and the change in thickness, that is, the absolute value of the deformation range is low. In particular, in the case of the porous support layer #1, the theoretically possible deformation range of the ultra-thin porous support layer is 4 μm. Therefore, when a thin porous support layer is used, it can be seen that the thickness of the porous support layer does not change significantly while absorbing the stress inside the bipolar all-solid-state battery.

Even excluding the pressure of the jig, when lithium of 1 mAh/cm 2 is typically deposited during charging, the lithium is deposited as a layer with a thickness of 4 μm on the anode. The present invention relates to a battery used in a small-sized or large-capacity battery used in automobiles, etc. In general, the capacity of an electrode is larger than that of a thin film battery, and the thickness of lithium deposited on the negative electrode increases as the capacity of the electrode increases. Therefore, when using a porous support layer with a small deformation range as in the present invention to relieve stress inside the bipolar all-solid-state battery, a plurality of porous support layers are used according to the thickness of the deposited lithium to relieve the stress inside the bipolar all-solid-state battery can do it As shown in Table 2, it can be seen that even when two or three porous support layer #2 are stacked, the same operation is performed as when one porous support layer #2 is stacked.

When comparing the case where the porous support layer #3 and the porous support layer #3 were pressurized at 10 MPa, when the unpressurized porous support layer #3 was pressurized at 5 MPa once, the thickness decreased from 41 μm to 38 μm, After that, as the number of pressurization increases, the thickness continuously decreases to form a compact deformation, but when this is used after primary molding at a pressure higher than the driving pressure, that is, when the porous support layer #3 is pressurized to 10 MPa, additional pressurization is continued thereafter. It can be seen that there is no change in thickness. Therefore, when a thin porous support layer such as porous support layer #2 is laminated in multiple layers or a thick porous support layer such as porous support layer #3 is molded at a high pressure compared to the driving pressure, the stress inside the bipolar all-solid-state battery can be reduced. can

(Experimental Example 2) Thickness increase rate measurement experiment

In Experimental Example 2, the thickness change rate was calculated by charging and discharging the battery formed as follows 5 times. The initial capacity of the battery was measured by charging and discharging under 60°C conditions, charging conditions were CC/CV (8.5V, 0.05C, 0.01C current cut off), and discharging conditions were CC conditions (6V, 0.05C, 60°C). ) was performed. In this case, the thickness increase rate was calculated as the thickness of the battery after charging / the thickness of the battery before charging X 100, and is shown in Table 3 below. In addition, the capacity retention rate (retention) after charging and discharging 5 times was measured and shown in Table 3 below.

The capacity retention rate (retention) was calculated as follows.

Capacity retention rate (%) = (capacity in 5 cycles / initial capacity) X 100

(Example 1)

Dispersion of cathode active material NCM811 (LiNi _0.8 Co _0.1 Mn _0.1 O ₂ ), solid electrolyte, aradite (Li ₆ PS ₅ Cl), conductive material, carbon, and PTFE binder in anisole in a weight ratio of 77.5 : 19.5 : 1.5 : 1.5 and stirring to prepare a positive electrode slurry. The positive electrode slurry was applied to an aluminum current collector having a thickness of 15 μm using a doctor blade, and then vacuum dried at 100° C. for 12 hours to prepare a positive electrode having a capacity of 2 mAh/cm 2 .

A solid electrolyte layer was prepared by mixing agarodite (Li ₆ PS ₅ Cl) and a PTFE binder in a weight ratio of 95:5.

11 μm thick nickel was used as the negative electrode current collector.

5 is a cross-sectional view of the all-solid-state battery 1000 used in Experimental Example 2.

The all-solid-state battery of Experimental Example 2 includes a first positive electrode 1110 having a first positive electrode active material 1111 formed on one surface of the first positive electrode current collector 1112 , a first solid electrolyte layer 1120 , and a first negative electrode current collector It is formed by laminating a porous support layer 1300 between a first unit cell 1100 in which a negative electrode made of only 1132 is stacked and a second unit cell 1200 in which a negative electrode made of only a second negative electrode collector 1232 is stacked. . At this time, the first positive electrode active material 1111 is stacked to face the first solid electrolyte layer 1120 , and the second positive electrode active material 1211 is also the same. At this time, the first positive electrode current collector 1112 faces the jig (JIG), and the second positive electrode current collector 1212 faces the porous support layer 1300 .

The porous support layer 1300 used in Example 1 of the present invention was obtained by pressing the porous support layer #2 at 10 MPa, followed by stacking three sheets.

(Example 2)

In Example 1, the porous support layer 1300 was manufactured and evaluated in the same manner as in Example 1, except that one was used after pressing the porous support layer #2 at 10 MPa.

(Example 3)

Example 1 was manufactured and evaluated in the same manner as in Example 1, except that a positive electrode having a capacity of 3 mAh/cm 2 was used.

(Comparative Example 1)

It was manufactured and evaluated as in Example 1 except that the porous support was not applied in Example 1.

(Comparative Example 2)

In Example 1, the porous support layer #1 was pressurized to 20 MPa as the porous support layer 1300, and was manufactured and evaluated in the same manner as in Example 1, except that one was used.

(Comparative Example 3)

It was manufactured and evaluated in the same manner as in Example 1, except that one porous support layer #3 was used as the porous support layer 1300 in Example 1.

As can be seen in Table 3, when the elastic force of the porous support layer is greater than the battery driving pressure as in Examples 1 to 3 of the present invention, the porous support layer absorbs the thickness change due to lithium generated during charging, so that the all-solid-state battery It can be seen that the stress in the porous support layer is resolved. It can be seen that this thickness change resolution is continued even after 5 times of charging and discharging. Theoretically, in the case of the deformation amount of the porous support layer, the thickness and porosity of the porous support layer to be used can be calculated. It can be seen that there is almost no thickness increase rate during discharge.

On the other hand, in the case of Comparative Example 1 to which the porous support layer was not applied, the thickness of the all-solid-state battery increased, and accordingly, the resistance inside the all-solid-state battery increased, so that the lifetime was also inferior to that of Examples 1 to 3. . In addition, it can be seen that Comparative Example 2 using a porous support layer having a smaller displacement than the increased thickness and Comparative Example 3, in which the thickness is continuously changed during operation due to low elastic force, have insignificant effects even when the porous support layer is used. Therefore, it can be seen that the elastic range of the porous support layer should be greater than the deformation range due to the deposited lithium.

That is, since lithium with a thickness of 4 μm is deposited per 1 mAh/cm 2 of the capacity of the all-solid-state battery, the deformation range can be calculated based on the thickness and porosity of the porous support layer, and it can be stacked in more than one layer.

The present invention also provides a battery module, a battery pack, and a device including the battery pack including the bipolar all-solid-state battery, and the battery module, battery pack and device as described above are known in the art, so the present invention In the specification, a detailed description thereof will be omitted.

The device is, for example, a notebook computer, a netbook, a tablet PC, a mobile phone, an MP3, a wearable electronic device, a power tool, an electric vehicle (EV), a hybrid electric vehicle (HEV) , a Plug-in Hybrid Electric Vehicle (PHEV), an electric bicycle (E-bike), an electric scooter (E-scooter), an electric golf cart, or a system for power storage. However, it is needless to say that the present invention is not limited thereto.

Those of ordinary skill in the art to which the present invention pertains will be able to perform various applications and modifications within the scope of the present invention based on the above content.

10, 1000: bipolar all-solid-state battery
100, 1100: first unit cell
110, 1110: first anode
111, 1111: first positive electrode active material
112, 1112: first positive electrode current collector
120, 1120: first solid electrolyte layer
130, 1130: first cathode
131, 1131: first negative active material
132, 1132: first cathode current collector
200, 1200: second unit cell
210, 1210: second anode
211, 1211: second positive electrode active material
212, 1212: second positive electrode current collector
220, 1220: second solid electrolyte layer
230, 1230: second cathode
231, 1231: second anode active material
232, 1232: second cathode current collector
300: bipolar electrode
1300: porous support layer
400, 1400: lithium layer
F1 : Pressing force
F2 : internal pressure
m: thickness before pressing
M: thickness after pressing
JIG: Jig

Claims (15)

In an all-solid-state battery in which two or more unit cells including a positive electrode, a solid electrolyte layer, and a negative electrode are connected in series,
A portion where the unit cells are connected in series is provided with a porous support layer in the center, a negative electrode of one unit cell is disposed on one surface of the porous support layer, and a positive electrode of another unit cell is disposed on an opposite surface thereof. According to claim 1,
The anode is a bipolar all-solid-state battery that is a current collector without a lithium metal or active material layer. According to claim 1,
The porous support layer is
olefinic porous substrate; and
Sheets or nonwoven fabrics made of at least one selected from the group consisting of glass fiber or polyethylene;
A bipolar all-solid-state battery comprising at least one. 4. The method of claim 3,
The porous support layer,
A bipolar all-solid-state battery in which the olefinic porous substrate or sheet or nonwoven fabric is laminated in one or more layers. 5. The method of claim 4,
When the porous support layer is two or more layers,
Each layer of the porous support layer is made of a different material, or
All-solid-state battery made of the same material for each layer of the porous support layer. According to claim 1,
The thickness of the porous support layer decreases when pressure is applied, and when the pressure is released, the thickness returns to the bipolar all-solid-state battery to control the internal stress of the all-solid-state battery. 7. The method of claim 6,
The pressure is a bipolar all-solid-state battery that is generated as lithium ions of the positive electrode move to the negative electrode by charging and are deposited between the negative electrode and the solid electrolyte layer. 8. The method of claim 7,
The porous support layer is a bipolar all-solid-state battery to control the stress according to the thickness change due to lithium deposition. 7. The method of claim 6,
The porous support layer is a bipolar all-solid-state battery for controlling the stress in proportion to the thickness and porosity of the porous support layer. According to claim 1,
The porous support layer is a bipolar all-solid-state battery having a thickness of 20㎛ to 50㎛. According to claim 1,
The positive electrode is a bipolar all-solid-state battery comprising a positive electrode current collector and a positive electrode active material applied to one surface of the positive electrode current collector. 12. The method of claim 11,
The positive electrode active material faces the solid electrolyte layer, and the positive electrode current collector faces the porous support layer. According to claim 1,
The negative electrode of one unit cell disposed on one surface of the porous support layer is lithium metal without a separate active material layer, and the positive electrode of another unit cell disposed on the opposite surface of the porous support layer is a positive electrode current collector. According to claim 1,
The unit cell is a bipolar all-solid-state battery accommodated in a pouch-type battery case. According to claim 1,
The unit cell is a bipolar all-solid-state battery to which pressure is applied by a jig when in use.

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