Bipolar all-solid-state battery including porous support layer

Abstract

The present invention relates to a bipolar solid-state battery including a porous support layer, and particularly to a bipolar solid-state battery in which: (a) at least two unit cells each including a positive electrode, a solid electrolyte, and a negative electrode are connected in series with each other, and a first porous support layer is disposed in the center of a connection portion; or (b) at least two unit cells each including a positive electrode, a solid electrolyte, and a second porous support layer are connected in series with each other.

Description

Technical Field

[0001] This application claims priority to Korean Patent Application No. 2020-0142129, filed on October 29, 2020, and Korean Patent Application No. 2020-0147423, filed on November 6, 2020, the disclosures of which are incorporated herein by reference in their entirety.

[0002] This invention relates to a bipolar all-solid-state battery including a porous support layer. More specifically, this invention relates to a bipolar all-solid-state battery configured such that (a) two or more cell units, each including a positive electrode, a solid electrolyte, and a negative electrode, are connected in series with each other, and a first porous support layer is disposed at the interface between the two or more cell units; or (b) two or more cell units, each including a positive electrode, a solid electrolyte, and a second porous support layer, are connected in series with each other. Background Technology

[0003] The advantages of bipolar batteries are: minimized casing volume, resulting in high energy density, stable performance, and low internal resistance. Generally, bipolar batteries have bipolar electrodes configured to connect a single cell and adjacent cells in series. The bipolar electrodes consist of a bipolar electrode layer and bipolar plates. The bipolar plates can be made of a material with sufficient conductivity to conduct current between cells, chemical stability within the battery, and good contact with the electrodes. However, the bipolar plates are susceptible to corrosion by the high-dielectric electrolyte primarily used in lithium-ion batteries. Corroded plates reduce the electrolyte's sealing properties and the insulation between cells, inducing internal short circuits and ultimately compromising battery safety.

[0004] To address this issue, a bipolar all-solid-state battery that does not use an electrolyte is proposed as an alternative. Unlike traditional secondary batteries, the bipolar all-solid-state battery has a solid electrolyte, which is arranged between the positive and negative electrodes to act as a separator.

[0005] Because all-solid-state batteries use a solid electrolyte instead of the liquid electrolyte used in traditional batteries, electrolyte evaporation due to temperature changes or leakage due to external impacts does not occur, thus preventing explosions or fires. The contact area between the solid electrolyte and the positive or negative electrode is limited; therefore, interfaces are not easily formed between the positive electrode and the solid electrolyte, or between the negative electrode and the solid electrolyte. When the contact area between the positive electrode and the solid electrolyte, or between the negative electrode and the solid electrolyte, is small, as described above, the interface resistance is reduced by pressing the cell containing the solid electrolyte.

[0006] Meanwhile, lithium can be used to manufacture bipolar all-solid-state batteries to improve their density, capacity, and lifespan. However, when using lithium, lithium dendrites can form during charging and discharging, damaging the separator (solid electrolyte) or causing them to contact the positive electrode, resulting in a short circuit within the cell. Particularly when pressing bipolar all-solid-state batteries, the growth of lithium dendrites brings the positive, solid electrolyte, and negative electrodes closer together, damaging the solid electrolyte or causing a short circuit due to the reaction between the lithium dendrites and the positive electrode.

[0007] Figure 1 This is a 3D view of a traditional bipolar all-solid-state battery before charging and discharging. Figure 2 This is a 3D view of a traditional bipolar all-solid-state battery after charging and discharging.

[0008] A conventional bipolar all-solid-state battery 10 includes a first cell 100, a second cell 200, and a bipolar electrode 300. The first cell 100 includes: a first positive electrode 110, which includes a first positive active material 111 and a first positive current collector 112; a first solid electrolyte 120; and a first negative electrode 130, which includes a first negative active material 131 and a first negative current collector 132. The second cell 200 includes: a second positive electrode 210, which includes a second positive active material 211 and a second positive current collector 212; a second solid electrolyte 220; and a second negative electrode 230, which includes a second negative active material 231 and a second negative current collector 232. The bipolar electrode 300 is configured to connect the first cell 100 and the second cell 200 in series.

[0009] At this time, with Figure 1 and Figure 2 In contrast, each of 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 can be coated onto a surface of a corresponding one of 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 232, or they can be left uncoated.

[0010] In addition, unlike the above structure, a bipolar all-solid-state battery can be provided, in which the first negative electrode active material, the bipolar electrode, and the second positive electrode active material are arranged between the first solid electrolyte 120 and the second solid electrolyte 220. This also has the problems described below.

[0011] In order to reduce the interface resistance between the first positive electrode 110, the first solid electrolyte 120 and the first negative electrode 130, as well as the second positive electrode 210, the second solid electrolyte 220 and the second negative electrode 230, the conventional bipolar all-solid-state battery 10 is pressed by the Y-axis pressing force F1 from the clamp during charging and discharging.

[0012] However, in the bipolar all-solid-state battery 10, the lithium layer 400 formed during the charging and discharging process of the first cell 100 and the second cell 200 is inserted into the first negative electrode 130 and / or the second negative electrode 230, thereby causing the active material to expand or lithium to be deposited on the first negative electrode 130 and / or the second negative electrode 230, thus increasing the thickness of the bipolar all-solid-state battery 10.

[0013] If the thickness of the bipolar all-solid-state battery 10 increases, the internal pressure F2 of the bipolar all-solid-state battery 10 increases, thereby increasing the pressing force F1 applied to the first cell 100 and the second cell 200. This is because, generally speaking, the pressing force F1 is generated by a clamp occupying a certain position, thus increasing the internal volume of the bipolar all-solid-state battery.

[0014] As the lithium layer 400 formed during the initial charge and discharge increases, the reaction force between the first solid electrolyte 120 and the second solid electrolyte 220 and the lithium layer 400 increases. The lithium metal in the lithium layer 400 is introduced into the bipolar all-solid-state battery 10 through the defects of the first solid electrolyte 120 and the second solid electrolyte 220, thereby increasing the possibility of a short circuit in the bipolar all-solid-state battery 10.

[0015] Furthermore, as the pressing force F1 increases, the position or shape of the first cell 100 and the second cell 200 in the bipolar all-solid-state battery 10 may change. If the shape of the bipolar all-solid-state battery 10 or the position of the first cell 100 and the second cell 200 changes, the pressing force F1 is not applied evenly to the first cell 100 and the second cell 200; thus, some cells may not be pressed, or others may be over-pressed.

[0016] Patent document 1, which relates to an all-solid-state thin-film stacked battery, mentions a case in which multiple power generation elements are connected in series with each other, wherein the power generation elements are connected in series with each other via electrode terminals, thereby relieving stress in the thin-film stacked battery; however, unlike the bipolar battery according to the present invention, the density of this battery is not increased.

[0017] Therefore, it is necessary to prevent damage to the solid electrolyte caused by lithium dendrites, while reducing stress in bipolar all-solid-state batteries with superior performance relative to density; however, no clear solution has yet been proposed.

[0018] (Patent Document 1) Japanese Patent Application Publication No. 2004-273436 (September 30, 2004) (“Patent Document 1”). Summary of the Invention

[0019] Technical issues

[0020] The present invention was made in view of the above problems. The purpose of the present invention is to prevent damage to the solid electrolyte due to the formation of lithium dendrites and to prevent short circuits in the cell due to contact between lithium dendrites and the positive electrode.

[0021] Another objective of this invention is to reduce stress in bipolar all-solid-state batteries and improve ionic conductivity, thereby increasing the lifespan and density of bipolar all-solid-state batteries.

[0022] Technical solution

[0023] To achieve the above objectives, the present invention provides a bipolar all-solid-state battery configured such that: (a) two or more cell units, each comprising a positive electrode, a solid electrolyte, and a negative electrode, are connected in series, and a first porous support layer is disposed at the interface between the two or more cell units; or

[0024] (b) Each of the two or more unit cells, including a positive electrode, a solid electrolyte, and a second porous support layer, are connected in series with each other.

[0025] The negative electrode of one of the cell units can be disposed on one surface of the first porous support layer, and the positive electrode of the other cell unit can be disposed on the opposite surface of the first porous support layer. The negative electrode can be lithium metal or a current collector without an active material layer.

[0026] The surface of the second porous support layer facing the solid electrolyte can be used as a negative electrode, and the surface of the second porous support layer facing the positive electrode can be used as a separator. The second porous support layer may include a lithium negative electrode or a negative electrode current collector. The negative electrode current collector may be a metal or a metal oxide. The lithium negative electrode or the negative electrode current collector may not include a separate active material layer.

[0027] The first porous support layer may include at least one of the following: an olefin-based porous substrate; and a sheet or nonwoven fabric made using at least one of the groups consisting of glass fiber and polyethylene.

[0028] The first porous support layer may be configured to have the olefin-based porous substrate, the sheet, or the nonwoven fabric stacked into one or more layers. When the first porous support layer is formed to have two or more layers, the layers of the first porous support layer may be made of different materials, or the layers of the first porous support layer may be made of the same material.

[0029] Each of the first and second porous support layers is configured such that its thickness decreases when pressure is applied and recovers when the pressure is released, thereby adjusting the stress in the all-solid-state battery. The pressure may be a result of lithium ions moving from the positive electrode to the negative electrode during charging and depositing between the negative electrode and the solid electrolyte, or depositing between the second porous support layer and the solid electrolyte.

[0030] The first porous support layer can adjust the stress caused by the thickness change due to lithium deposition, and the thickness of the second porous support layer can be greater than the thickness of the deposited lithium.

[0031] The stress can be adjusted proportionally to the thickness and porosity of each of the first porous support layer and the second porous support layer, and the thickness of the first porous support layer can be from 20 μm to 50 μm.

[0032] 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, and the positive electrode current collector may face the first porous support layer and the second porous support layer.

[0033] The negative electrode of one of the cell units arranged on one surface of the first porous support layer can be lithium metal without a separate active material layer, and the positive electrode of the other cell unit arranged on the opposite surface of the first porous support layer can be a positive current collector.

[0034] In the positive electrode, the positive electrode disposed between the second porous support layer and the solid electrolyte may be composed solely of positive electrode active material, and in this case, the outermost positive electrode may include a positive electrode current collector and a positive electrode active material applied to the surface of the positive electrode current collector facing the solid electrolyte.

[0035] The two or more cell units can be housed in a pouch-shaped battery casing, and the two or more cell units can be pressed by external clamps during their charging and discharging processes.

[0036] A bipolar all-solid-state battery, in which two or more cell units, each comprising the positive electrode, the solid electrolyte, and the second porous support layer, are connected in series, can be configured such that one or more cell stacks, each comprising the second porous support layer, positive electrode active material, and solid electrolyte, are repeatedly disposed between the outermost positive electrode and the solid electrolyte facing the outermost positive electrode and the outermost negative electrode.

[0037] A bipolar all-solid-state battery, in which two or more cell units, each comprising the positive electrode, the solid electrolyte, and the second porous support layer, are connected in series, can be configured such that one or more cell stacks, each comprising the second porous support layer, a positive electrode current collector, a positive electrode active material, and a solid electrolyte, are repeatedly disposed between the outermost positive electrode and the solid electrolyte facing the outermost positive electrode and the outermost negative electrode.

[0038] The present invention can provide a battery module or battery pack including the aforementioned bipolar all-solid-state battery. Furthermore, the present invention can also provide an apparatus in which the aforementioned bipolar all-solid-state battery is mounted.

[0039] In this invention, one or more non-conflicting structures can be selected and combined from the above-described structures.

[0040] Beneficial effects

[0041] As can be seen from the above description, in the bipolar all-solid-state battery according to the present invention, the stress caused by the formation of the lithium layer in the bipolar all-solid-state battery can be reduced, thereby preventing damage to the solid electrolyte or the reaction between the positive electrode and the lithium dendrites of the lithium layer, and thus reducing battery short circuits in the bipolar all-solid-state battery.

[0042] In addition, in bipolar all-solid-state batteries, only the negative current collector is used as the negative electrode, and the positive current collector and the positive active material applied to one surface of the positive current collector are used as the positive electrode. The cell cells formed in this way are connected in series with each other through the first porous support layer, thereby increasing the battery capacity based on its density while improving battery performance.

[0043] Furthermore, the bipolar all-solid-state battery has a second porous support layer that serves as both the negative electrode and the separator, and this second porous support layer alleviates stress in the bipolar all-solid-state battery, thereby enabling the acquisition of a bipolar all-solid-state battery with improved safety and high density.

[0044] Furthermore, the pressure applied to the cell in the bipolar all-solid-state battery is maintained uniformly, thereby preventing damage to the cell and improving the ionic conductivity of the cell, thus extending the battery's lifespan. Attached Figure Description

[0045] Figure 1This is a 3D view of a traditional bipolar all-solid-state battery before charging and discharging.

[0046] Figure 2 This is a 3D view of a traditional bipolar all-solid-state battery after charging and discharging.

[0047] Figure 3 This is a perspective view of a bipolar all-solid-state battery before charging and discharging according to the first embodiment of the present invention.

[0048] Figure 4 This is a perspective view of a bipolar all-solid-state battery after charging and discharging according to a first embodiment of the present invention.

[0049] Figure 5 This is a cross-sectional view of the all-solid-state battery used in Experimental Example 2 of the present invention.

[0050] Figure 6 This is a perspective view of a bipolar all-solid-state battery before charging and discharging according to a second embodiment of the present invention.

[0051] Figure 7 This is a perspective view of a bipolar all-solid-state battery after charging and discharging according to a second embodiment of the present invention.

[0052] Figure 8 This is a cross-sectional view of the all-solid-state battery used in Experimental Example 4 of the present invention. Detailed Implementation

[0053] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that those skilled in the art can readily implement these preferred embodiments. However, in describing the operational principles of the preferred embodiments of the present invention, detailed descriptions of known functions and configurations incorporated herein may obscure the subject matter of the invention, and such detailed descriptions will be omitted.

[0054] Furthermore, in all figures, the same reference numerals will be used for components performing similar functions or operations. Throughout the specification, when a component is referred to as being connected to another component, this means not only that the one component can be directly connected to the other component, but also that the one component can be indirectly connected to the other component via other components. Moreover, including an element does not mean that other elements are excluded, but rather that such elements can be further included, unless otherwise mentioned.

[0055] Furthermore, the description of elements by limiting or adding details can be applied to all inventions, and does not limit any particular invention unless otherwise specified.

[0056] Furthermore, in the description of the invention and the claims of this application, unless otherwise stated, the singular form is intended to include the plural form.

[0057] Furthermore, in the description and claims of this application, "or" includes "and," unless otherwise mentioned. Therefore, "including A or B" refers to three cases: including A, including B, and including both A and B.

[0058] In addition, all ranges of numbers include the minimum, maximum, and all intermediate values ​​in between, unless the context explicitly states otherwise.

[0059] Combination Figures 1 to 8 Each of the active materials, current collectors, and solid electrolytes mentioned refers not just to a single material, but to a layer that includes that material.

[0060] The bipolar all-solid-state battery according to the present invention is characterized in that: (a) each comprises two or more unit cells, each including a positive electrode, a solid electrolyte, and a negative electrode, connected in series, and a first porous support layer is disposed at the interface between the two or more unit cells; or

[0061] (b) Each of the two or more unit cells, including a positive electrode, a solid electrolyte, and a second porous support layer, are connected in series with each other.

[0062] The negative electrode of one cell can be arranged on one surface of the first porous support layer, and the positive electrode of another cell can be arranged on the opposite surface of the first porous support layer. The negative electrode can be lithium metal or a current collector without an active material layer.

[0063] Reference Figure 3 and Figure 4 The first embodiment of the bipolar all-solid-state battery according to the present invention is described, wherein the bipolar all-solid-state battery is configured such that (a) two or more cell units, each comprising a positive electrode, a solid electrolyte and a negative electrode, are connected in series with each other, and a first porous support layer is provided at the interface between the two or more cell units.

[0064] Figure 3 This is a perspective view of the bipolar all-solid-state battery 1000 according to the first embodiment of the present invention before charging and discharging, and Figure 4 This is a perspective view of the bipolar all-solid-state battery 1000 according to the first embodiment of the present invention after charging and discharging.

[0065] exist Figure 3 and Figure 4 In this context, for ease of description, the cell is shown as a first cell 1100 and a second cell 1200. However, the cell may include a plurality of first cell 1100 and a plurality of second cell 1200.

[0066] The bipolar all-solid-state battery 1000 according to the present invention includes a first cell 1100 and a second cell 1200. The first cell 1100 includes: a first positive electrode 1110, comprising a first positive electrode active material 1111 and a first positive electrode current collector 1112; a first solid electrolyte 1120; and a first negative electrode 1130, comprising a first negative electrode current collector 1132. The second cell 1200 includes: a second positive electrode 1210, comprising a second positive electrode active material 1211 and a second positive electrode current collector 1212; a second solid electrolyte 1220; and a second negative electrode 1230, comprising a second negative electrode current collector 1232. A first porous support layer 1300 is disposed between the first cell 1100 and the second cell 1200, the first porous support layer being configured to connect the cell cells in series. The first negative electrode 1130 of the first cell 1100 is arranged on one surface of the first porous support layer 1300, and the second positive electrode 1210 of the second cell 1200 is arranged on the other surface of the first porous support layer 1300, that is, the surface of the first porous support layer opposite to the first negative electrode 1130.

[0067] The first positive electrode 1110 can be manufactured using methods such as applying a positive electrode mixture consisting of positive electrode active material particles, a conductive agent, and a binder to a first positive electrode current collector 1112 to form the first positive electrode active material 1111. If necessary, fillers can be further added to the positive electrode mixture.

[0068] Generally, the first positive electrode current collector 1112 is manufactured with a thickness of 3 μm to 500 μm. There are no particular limitations on the first positive electrode current collector, provided it exhibits high conductivity and does not induce any chemical changes in the battery in which it is used. For example, the first positive electrode current collector can be made of stainless steel, aluminum, nickel, or titanium. Alternatively, the positive electrode current collector can be made of aluminum or stainless steel, with its surface treated with carbon, nickel, titanium, or silver. Specifically, aluminum can be used. Microscale irregular patterns can be formed on the surface of the current collector to increase the adhesion of the positive electrode active material. The current collector can be configured in any of a variety of forms, such as a membrane, sheet, foil, mesh, porous body, foam, and nonwoven fabric.

[0069] In addition to the positive electrode active material particles, the positive electrode active material included in the first positive electrode active material 1111 can be composed of, for example, layered compounds such as lithium nickel oxide (LiNiO2) or compounds replaced by one or more transition metals; or compounds with the chemical formula Li 1+x Mn 2-xLithium manganese oxide represented by O4 (where x = 0 to 0.33) or lithium manganese oxides such as LiMnO3, LiMn2O3 or LiMnO2; lithium copper oxide (Li2CuO); vanadium oxide such as LiV3O8, LiV3O4, V2O5 or Cu2V2O7; and lithium oxides with the chemical formula LiNi 1-x M x Lithium oxide at the nickel site, represented by O2 (where M = Co, Mn, Al, Cu, Fe, Mg, B, or Ga, x = 0.01 to 0.3); and by the chemical formula LiMn 2-x M x Lithium-manganese composite oxides represented by O2 (where M = Co, Ni, Fe, Cr, Zn or Ta, x = 0.01 to 0.1) or the chemical formula Li2Mn3MO8 (where M = Fe, Co, Ni, Cu or Zn); LiMn2O4, wherein a portion of the Li in the chemical formula is replaced by an alkaline earth metal ion; disulfide compounds; or Fe2(MoO4)3. However, the invention is not limited thereto.

[0070] However, the positive electrode active material 1111 used in this invention is preferably a metal oxide including lithium, or includes the metal oxide, so as to deposit lithium on the first negative electrode 1130.

[0071] Generally, conductive agents are added to a proportion ranging from 0.1% to 30% by weight of the total compound, including the positive electrode active material. There are no particular limitations on conductive agents as long as they do not induce any chemical changes and exhibit high conductivity in the battery in which they are applied. Examples include graphite (such as natural or artificial graphite); carbon black (such as carbon black, acetylene black, Kirschner black, channel black, furnace black, lamp black, or thermal black); conductive fibers (such as carbon fibers or metal fibers); metal powders (such as fluorinated carbon powder, aluminum powder, or nickel powder); conductive whiskers (such as zinc oxide or potassium titanate); conductive metal oxides (such as titanium oxide); or conductive materials (such as polystyrene derivatives).

[0072] The binder included in the first positive electrode 1110 is a component that assists in the bonding between the active material and the conductive agent, as well as the bonding with the current collector. The amount of binder added is generally from 0.1% to 30% by weight of the total weight of the mixture including the positive electrode active material. Examples of binders that can be used include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, fluororubber, and various copolymers.

[0073] The first positive electrode 1110 can be configured to have a structure in which the first positive electrode active material 1111 is formed on at least one surface of the first positive electrode current collector 1112. 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 can be configured to have a structure in which the first positive electrode active material 1111 is applied to two opposing surfaces of the first positive electrode current collector 1112. Alternatively, when the first positive electrode 1110 faces another cell of the bipolar all-solid-state battery 1000, the first positive electrode 1110 can be configured to have a structure in which the first positive electrode active material 1111 is applied to only one surface of the first positive electrode current collector 1112.

[0074] The second positive electrode 1210 can be formed in the same manner as the first positive electrode 1110. However, the second positive electrode 1210 faces the cell of the bipolar all-solid-state battery 1000, and the second positive electrode active material 1211 is formed on only one surface of the second positive electrode current collector 1212 of the second positive electrode 1210.

[0075] The second positive electrode active material 1211 of the second positive electrode 1210 disposed on the other surface of the first porous support layer 1300 faces the second solid electrolyte 1220, and the second positive electrode current collector 1212 faces the first porous support layer 1300. Therefore, the cell cells of the bipolar all-solid-state battery 1000 are connected in series with each other via the first porous support layer 1300.

[0076] An organic solid electrolyte or an inorganic solid electrolyte can be used as each of the first solid electrolyte 1120 and the second solid electrolyte 1220. However, the invention is not limited thereto.

[0077] For example, polyethylene derivatives, polyethylene oxide derivatives, polypropylene oxide derivatives, phosphate polymers, polylysine, polyester sulfides, polyvinyl alcohol, polyvinylidene fluoride, or polymers containing ion-dissociating groups can be used as organic solid electrolytes.

[0078] As an example, the inorganic solid electrolyte can be a sulfide-based solid electrolyte or an oxide-based solid electrolyte.

[0079] For example, such as Li 6.25 La3Zr2A l0.25 O 12 Li3PO4, Li3+xPO4-xN x Nitrides or halides of Li such as (LiPON), Li3N, LiI, Li5NI2, Li3N-LiI-LiOH, LiSiO4, LiSiO4-LiI-LiOH, Li2SiS3, Li4SiO4 or Li4SiO4-LiI-LiOH can be used as oxide-based solid electrolytes.

[0080] In this invention, there are no particular limitations on the sulfide-based solid electrolyte; all known sulfide-based materials used in the field of lithium batteries can be employed. Commercially available products can be used as sulfide-based materials, or amorphous sulfide-based materials can be crystallized to manufacture sulfide-based materials. For example, crystalline sulfide-based solid electrolytes, amorphous sulfide-based solid electrolytes, or mixtures thereof can be used as sulfide-based solid electrolytes. Examples of usable composite compounds include sulfur-halogen compounds, sulfur-germanium compounds, and sulfur-silicon compounds. Specifically, sulfides such as SiS2, GeS2, or B2S3 can be included, and Li3PO4, halogens, or halogen compounds can be added. Preferably, a compound capable of implementing 10 -4 Sulfide-based electrolytes with lithium-ion conductivity of S / cm or higher.

[0081] Typically, this includes Li6PS5Cl (LPSCl), Thio-LISICON (Li 3.25 Ge 0.25 P 0.75 S4), Li2S-P2S5-LiCl, Li2S-SiS2, LiI-Li2S-SiS2, LiI-Li2S-P2S5, LiI-Li2S-P2O5, LiI-Li3PO4-P2S5, Li2S-P2S5, Li3PS4, Li7P3S 11 , LiI-Li2S-B2S3, Li3PO4-Li2S-Si2S, Li3PO4-Li2S-SiS2, LiPO4-Li2S-SiS, Li 10 GeP2S 12 Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 and Li7P3S 11 .

[0082] Each of the first solid electrolyte 1120 and the second solid electrolyte 1220 has a coating disposed on the surface of the first negative electrode 1130 and the corresponding one of the second negative electrode 1230, the coating being configured to induce the formation of lithium dendrites.

[0083] The coating may include a metal to improve electrical and ionic conductivity. The type of metal is not limited, as long as it enables the formation of lithium dendrites between the coating and the first negative electrode current collector 1132 or between the coating and the second negative electrode current collector 1232, while simultaneously improving the performance of the first negative electrode 1130 or the second negative electrode 1230. In this case, the metal may be lithiophilic to induce the formation of lithium dendrites between the coating and the first negative electrode current collector 1132 or between the coating and the second negative electrode current collector 1232.

[0084] At this time, the lithium-loving metal can be arranged on the surface of the coating facing the first negative electrode 1130 or the second negative electrode 1230, so that no lithium dendrites grow in the direction toward the first solid electrolyte 1120 or the second solid electrolyte 1220.

[0085] When the lithium-loving metal is located on the coating, lithium is plated on the lithium-loving metal, thereby forming lithium nuclei, and lithium dendrites grow only from the lithium nuclei on the coating.

[0086] At least one of a metal and a metal oxide can be selected as the lithiophilic material. For example, the metal can be gold (Au), silver (Ag), platinum (Pt), zinc (Zn), silicon (Si), or magnesium (Mg), and the metal oxide can be copper oxide, zinc oxide, or cobalt oxide, which is a nonmetal.

[0087] According to the present invention, the first negative electrode 1130 may be composed only of the first negative electrode current collector 1132.

[0088] The first negative electrode current collector 1132 is typically manufactured with a thickness of 3 μm to 500 μm. There are no particular limitations on the first negative electrode current collector 1132, as long as it exhibits conductivity and does not induce any chemical changes in the battery in which it is used. The first negative electrode current collector 1132 can be an electrode current collector without a lithium metal or separate negative electrode active material layer. For example, the first negative electrode current collector can be made of copper, stainless steel, aluminum, nickel, titanium, or sintered carbon. Alternatively, the first negative electrode current collector can be made of copper or stainless steel, with its surface treated with carbon, nickel, titanium, or silver, or an aluminum-cadmium alloy. Furthermore, the first negative electrode current collector can have microscale irregular patterns formed on its surface in the same manner as the first positive electrode current collector 1112 to increase the adhesion of the negative electrode active material. The first negative electrode current collector can be configured in any of a variety of forms, such as a film, sheet, foil, mesh, porous body, foam, and nonwoven fabric.

[0089] The second negative electrode 1230 can have the same structure as the first negative electrode 1130.

[0090] The first cell 1100 and the second cell 1200, each configured with the above structure, can be connected in series to obtain a bipolar all-solid-state battery 1000 with high energy density.

[0091] The first porous support layer 1300 can be arranged between the first unit cell 1100 and the second unit cell 1200 so as to connect the unit cells in series with each other.

[0092] All materials possessing electrical and ionic conductivity can be used as the first porous support layer 1300 to connect the first unit cell 1100 and the second unit cell 1200 in series. As one embodiment, the first porous support layer 1300 may comprise an olefin-based porous substrate and at least one sheet or nonwoven fabric manufactured using at least one selected from the group consisting of glass fibers and polyethylene. In this case, the first porous support layer 1300 is preferably an olefin-based porous substrate or a sheet manufactured using at least one selected from the group consisting of glass fibers and polyethylene. Nonwoven fabrics have high porosity. However, to achieve a predetermined strength in the first porous support layer 1300, multiple layers of nonwoven fabric must be stacked. Therefore, under the same thickness conditions, the thickness variation rate of the nonwoven fabric is smaller than that of the porous substrate or sheet.

[0093] Specifically, the first porous support layer 1300 may comprise a resin such as a polyolefin-based resin (polyethylene, polypropylene, polybutene, or polyvinyl chloride) or a mixture or copolymer thereof, or may comprise a resin such as polyethylene terephthalate, polycyclic olefins, polyethersulfone, polyamide, polyimide, polyimide-amide, polyaramid, nylon, or polytetrafluoroethylene. Polyolefin-based resins are preferred because they reduce the thickness of the first porous support layer, thereby increasing the volumetric capacity of the bipolar all-solid-state battery 1000.

[0094] The first porous support layer 1300 may be made of an elastic material that can alleviate the stress generated in the bipolar all-solid-state battery 1000, or the stress generated in the bipolar all-solid-state battery 1000 may be alleviated through the pores of the first porous support layer 1300.

[0095] The first porous support layer can be configured to have a structure in which porous substrates, sheets or nonwoven fabrics are stacked to have one or more layers.

[0096] When the first porous support layer is formed to have multiple layers, the range of stress that the first porous support layer can alleviate can be expanded.

[0097] When the first porous support layer is formed to have two or more layers, each layer of the first porous support layer may be made of different materials, or each layer of the first porous support layer may be made of the same material.

[0098] The pore diameter of the first porous support layer 1300 can typically be from 0.01 μm to 10 μm, and the thickness of the first porous support layer can typically be from 20 μm to 50 μm. In this case, the porosity of the first porous support layer 1300 can be from 30% to 90%.

[0099] The first porous support layer 1300 can adjust for stress caused by thickness variations due to lithium deposition. To alleviate stress in the first porous support layer 1300 as described above, the elastic range of the first porous support layer 1300 must be greater than its deformation range caused by the deposited lithium. The elastic range of the first porous support layer 1300 is proportional to its thickness and porosity.

[0100] That is, the elastic range of the first porous support layer 1300 can be expressed as follows.

[0101] The elastic range of the first porous support layer = the thickness of the first porous support layer × the porosity of the first porous support layer.

[0102] At this point, the elastic force of the material used for the first porous support layer 1300 must be greater than the driving pressure of the clamp.

[0103] A first porous support layer 1300 can be disposed between the first negative current collector 1132 of the first cell 1100 and the second positive current collector 1212 of the second cell 1200, such that the first porous support layer 1300, the first negative current collector 1132, and the second positive current collector 1212 serve as bipolar electrodes of the bipolar all-solid-state battery 1000. Since, as described above, the first cell 1100, the second cell 1200, and the bipolar electrodes partially share resources, the density of the bipolar all-solid-state battery 1000 can be improved. For this purpose, the first porous support layer 1300 is pressed between the first cell 1100 and the second cell 1200.

[0104] A uniform pressing force F1 is applied to the first cell 1100, the second cell 1200 and the first porous support layer 1300 by means of a clamp, and this pressing force is maintained even when using a bipolar all-solid-state battery 1000.

[0105] In the bipolar all-solid-state battery 1000 according to the present invention, such as Figure 4As shown, a lithium layer 1400 is formed after charging and discharging. The formation of the lithium layer 1400 is due to lithium deposition between the first negative electrode 1130 and the first solid electrolyte 1120 or between the second negative electrode 1230 and the second solid electrolyte 1220 during charging and discharging. This is because lithium ions move from the first positive electrode 1110 to the first negative electrode 1130 or from the second positive electrode 1210 to the second negative electrode 1230, and then deposit between the first negative electrode 1130 and the first solid electrolyte 1120 or between the second negative electrode 1230 and the second solid electrolyte 1220.

[0106] The lithium layer 1400 is charged under constant current / constant voltage (CC / CV) conditions. During this charging, the pressure F1 applied to the entire lithium secondary battery varies depending on the amount of lithium formed in the battery, the charging / discharging rate, and the charging / discharging time. This is due to the formation of the lithium layer 1400, which generates an internal pressure F2.

[0107] 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 relieved by means of the first porous support layer 1300. By reducing the pore size of the first porous support layer 1300 or by deforming the first porous support layer 1300 (including reducing its thickness), the first porous support layer 1300 applies a uniform pressing force F1 to the entire bipolar all-solid-state battery 1000.

[0108] The pore size of the first porous support layer 1300 can be reduced or deformed based on the formation and / or disappearance of the lithium layer 1400. For example, when the lithium layer 1400 is formed, thereby generating an internal pressure F2, the pore size and thickness of the first porous support layer 1300 can be reduced. Furthermore, when the lithium layer 1400 disappears, the first porous support layer 1300 returns to its initial state. Therefore, the thickness m of the bipolar all-solid-state battery before pressing and the thickness M of the bipolar all-solid-state battery after pressing remain equal to each other.

[0109] In order to ensure that the bipolar all-solid-state battery 1000 is evenly pressed evenly during the use of the cell units, all the cell units of the bipolar all-solid-state battery 1000 can be housed in a battery casing that allows the cell units to be pressed, or the cell units can be housed in a pouch-shaped battery casing, and then the bipolar all-solid-state battery 1000 can be pressed outside the pouch-shaped battery casing.

[0110] Reference Figure 6 and Figure 7 The bipolar all-solid-state battery is described as a second embodiment of the bipolar all-solid-state battery according to the present invention, which is configured such that: (b) two or more cell units, each including a positive electrode, a solid electrolyte and a second porous support layer, are connected in series with each other.

[0111] Figure 6 This is a perspective view of the bipolar all-solid-state battery 2000 according to the second embodiment of the present invention before charging and discharging. Figure 7 This is a perspective view of a bipolar all-solid-state battery 2000 after charging and discharging according to a second embodiment of the present invention.

[0112] exist Figure 6 and Figure 7 In this illustration, for ease of description, the cell is shown as a first cell 2100 and a second cell 2200. However, the cell may include a plurality of first cell 2100s and a plurality of second cell 2200s.

[0113] A bipolar all-solid-state battery 2000 according to a second embodiment of the present invention includes a first cell 2100 and a second cell 2200. The first cell 2100 includes: a first positive electrode 2110, which includes a first positive electrode active material 2111 and a first positive electrode current collector 2112; a first solid electrolyte 2120; and a second porous support layer 2140. The second cell 2200 includes: a second positive electrode 2210, which includes a second positive electrode active material 2211 and a second positive electrode current collector 2212; a second solid electrolyte 2220; and a second porous support layer 2240. The first cell 2100 and the second cell 2200 are connected in series with each other via the second porous support layer 2140 and the second porous support layer 2240.

[0114] At this point, the second positive current collector 2212 of the second cell 2200 can be omitted. Without the second positive current collector 2212, the positive electrode 2210 disposed between the second porous support layer 2140 and the solid electrolyte 2220 is composed only of the positive active material 2211, omitting the current collector 2212. As shown in the figure, the first positive electrode 2110, which is the outermost positive electrode, can also be composed of the positive current collector 2112 and the positive active material 2111 applied to the surface of the positive current collector 2112 facing the solid electrolyte 2120, or it can be composed of the positive current collector 2112 with positive active material applied to both opposite surfaces. Simultaneously, an additional current collector (not shown) can be added to the outer surface of the second porous support layer 2240, corresponding to the outermost negative electrode.

[0115] In addition, as Figure 6 and Figure 7 A variation of the bipolar all-solid-state battery according to the present invention can be configured to have a structure in which a first positive electrode, a second positive electrode, and a second negative electrode are not used, and only a second porous support layer is stacked with a solid electrolyte inserted therebetween. In this case, the positive electrode active material can be applied to one surface of the second porous support layer.

[0116] exist Figure 6 and Figure 7 The structure may include an outermost positive electrode 2110, an outermost solid electrolyte 2120, and an outermost negative electrode that are excluded, and a second porous support layer, a positive current collector, a positive active material, and a solid electrolyte are stacked therein, and this structure can be repeated. In this case, the repeated structure may consist of either the second porous support layer, the positive current collector, the positive active material, and the solid electrolyte, or it may consist of either the second porous support layer, the positive active material, and the solid electrolyte. Figure 6 and Figure 7 The most basic structure is shown, where the number of repeatable layers is 1.

[0117] The first solid electrolyte 2120 of the first cell 2100 is arranged on one surface of the second porous support layer 2140, and the second positive electrode 2210 of the second cell 2200 is arranged on the other surface of the second porous support layer 2140, that is, the surface of the second porous support layer opposite to the first solid electrolyte 2120.

[0118] The first positive electrode 2110 is the same as the first positive electrode 1110 in terms of its material and manufacturing method, the first positive electrode current collector 2112 is the same as the first positive electrode current collector 1112 in terms of its material and manufacturing method, and the first positive electrode active material 2111 is the same as the first positive electrode active material 1111 in terms of its material and manufacturing method.

[0119] However, the positive electrode active material 2111 used in this invention preferably uses a metal oxide including lithium or includes the metal oxide to deposit lithium on one surface of the second porous support layer 2140.

[0120] The first positive electrode 2110 can be configured to have a structure in which the first positive electrode active material 2111 is formed on at least one surface of the first positive electrode current collector 2112. When the first positive electrode 2110 is located on the outermost side of the bipolar all-solid-state battery 2000, the first positive electrode 2110 can be configured to have a structure in which the first positive electrode active material 2111 is applied to both opposing surfaces of the first positive electrode current collector 2112. In terms of battery performance, the structure in which the positive electrode active material is applied to the surface of the positive electrode current collector facing the solid electrolyte is more preferable than the structure in which the positive electrode active material is applied to both opposing surfaces of the positive electrode current collector.

[0121] When the first positive electrode 2110 faces the second porous support layer of another bipolar all-solid-state battery, the first positive electrode 2110 can be configured to have a structure in which the first positive electrode active material 2111 is applied only to the surface of the first positive electrode current collector 2112 facing the first solid electrolyte 2120, or it can be composed only of the first positive electrode active material 2111, on which other bipolar all-solid-state batteries can be stacked.

[0122] The second positive electrode 2210 may be made of the same material as the first positive electrode 2110. The second positive electrode 2210 is configured to have a structure in which the second positive electrode current collector 2212 and the second positive electrode active material 2211 are stacked sequentially facing the second porous support layer 2140. The second positive electrode 2210 may include only the second positive electrode active material 2211 and exclude the second positive electrode current collector 2212.

[0123] Specifically, the second positive electrode active material 2211 faces the second solid electrolyte 2220, and the second positive electrode current collector 2212 faces the second porous support layer 2140. Therefore, the cell units of the bipolar all-solid-state battery 2000 are connected in series via the second porous support layer 2140. The second porous support layer 2140 serves as a negative electrode, separator, and positive electrode, or as a negative electrode, current collector, and positive electrode.

[0124] The first solid electrolyte 2120 and the second solid electrolyte 2220 are the same as the first solid electrolyte 1120 and the second solid electrolyte 1220 in terms of materials and manufacturing methods.

[0125] Each of the first solid electrolyte 2120 and the second solid electrolyte 2220 may have a coating on the surface of the second porous support layer 2140 and the corresponding one of the second porous support layer 2240, the coating being configured to induce the formation of lithium dendrites.

[0126] The coating may include a metal to improve electrical and ionic conductivity. The type of metal is not limited, as long as it enables the formation of lithium dendrites between the coating and the second porous support layer 2140 or between the coating and the second porous support layer 2240, while simultaneously improving the negative electrode properties of the surface of the second porous support layer 2140 or the second porous support layer 2240 used as a negative electrode. The metal may be lithiophilic to induce the formation of lithium dendrites between the coating and the second porous support layer 2140 or between the coating and the second porous support layer 2240.

[0127] At this time, the lithium-loving metal can be arranged on the surface of the second porous support layer 2140 facing the first solid electrolyte 2120 or on the surface of the second porous support layer 2240 facing the second solid electrolyte 2220, so that no lithium dendrites grow in the direction toward the first solid electrolyte 2120 or the second solid electrolyte 2220.

[0128] When the lithium-loving metal is located on the coating, lithium is plated on the lithium-loving metal, thereby forming lithium nuclei, and lithium dendrites grow only from the lithium nuclei on the coating.

[0129] At least one of a metal and a metal oxide can be selected as the lithiophilic material. For example, the metal can be gold (Au), silver (Ag), platinum (Pt), zinc (Zn), silicon (Si), or magnesium (Mg), and the metal oxide can be copper oxide, zinc oxide, or cobalt oxide, which is a nonmetal.

[0130] The surface of the second porous support layer 2140 facing the first solid electrolyte 2120 according to the present invention can be used as a negative electrode, and the surface of the second porous support layer 2140 facing the second positive electrode 2210 can be used as a separator and / or current collector. When only the second positive electrode active material 2211 is used as the second positive electrode 2210, the surface of the second porous support layer 2140 facing the second positive electrode 2210 can simultaneously serve as a separator and a current collector.

[0131] The second porous support layer 2140 may include a lithium anode or a negative electrode current collector. There are no particular limitations on the lithium anode or negative electrode current collector included in the second porous support layer 2140, as long as the lithium anode or negative electrode current collector exhibits conductivity and does not induce any chemical changes in the battery using the lithium anode or negative electrode current collector. The negative electrode current collector can be a metal or a metal oxide. For example, the negative electrode current collector can be made of copper, stainless steel, aluminum, nickel, titanium, or sintered carbon. Alternatively, the first negative electrode current collector can be made of copper or stainless steel, with its surface treated with carbon, nickel, titanium, or silver, or an aluminum-cadmium alloy. Furthermore, the negative electrode current collector can have a microscale non-uniform pattern formed on its surface in the same manner as the first positive electrode current collector 2112 to increase the adhesion to the portion of the second porous support layer 2140 that serves as a separator. The negative electrode current collector can be configured in any of a variety of forms, such as a membrane, sheet, foil, mesh, porous body, foam, and nonwoven fabric. The lithium anode or anode current collector can be included in the second porous support layer 2140 as non-layered particles or core-shell particles.

[0132] The lithium anode or current collector of the second porous support layer 2140 according to the present invention may not include a separate active material. Since the lithium anode or current collector does not include a separate active material, the thickness of the second porous support layer 2140 can be reduced, thereby improving the battery density.

[0133] Generally, the second porous support layer 2140 can be formed with a thickness of 3 μm to 500 μm. In this case, the thickness of the second porous support layer 2140 can be greater than the thickness of the lithium layer 2400 formed as a result of lithium deposition.

[0134] The lithium anode or anode current collector of the second porous support layer 2140 can be mainly distributed on the surface of the second porous support layer facing the first solid electrolyte 2120.

[0135] Conductive material may be disposed on the surface of the second porous support layer 2140 facing the second positive electrode 2210. As an embodiment, the surface of the second porous support layer 2140 facing the second positive electrode 2210 may include an olefin-based porous substrate and at least one sheet or nonwoven fabric manufactured using at least one selected from the group consisting of glass fiber and polyethylene.

[0136] Specifically, the second porous support layer 2140 may comprise a resin such as a polyolefin-based resin (polyethylene, polypropylene, polybutene, or polyvinyl chloride) or a mixture or copolymer thereof, or may comprise a resin such as polyethylene terephthalate, polycyclic olefins, polyethersulfone, polyamide, polyimide, polyimide-amide, polyaramid, nylon, or polytetrafluoroethylene. Polyolefin-based resins are preferred because they reduce the thickness of the second porous support layer, thereby increasing the volumetric capacity of the bipolar all-solid-state battery 2000.

[0137] In addition, the surface of the second porous support layer 2140 facing the second positive electrode 2210 may include a composition similar to that of the first positive electrode current collector 2112.

[0138] The second porous support layer 2140 can be made of an elastic material capable of relieving stress generated in the bipolar all-solid-state battery 2000, or the stress generated in the bipolar all-solid-state battery 2000 can be relieved by utilizing the pores of the second porous support layer 2140. The interior of the second porous support layer 2140, made of a metallic material, can be porous foam.

[0139] The pore diameter of the second porous support layer 2140 can generally be from 0.01 μm to 10 μm, and the thickness of the second porous support layer can generally be from 20 μm to 50 μm.

[0140] The second porous support layer 2140 can be disposed between the first solid electrolyte 2120 of the first cell 2100 and the second positive current collector 2212 of the second cell 2200, such that the second porous support layer 2140 and the second positive current collector 2212 serve as bipolar electrodes of the bipolar all-solid-state battery 2000. As described above, since the bipolar electrodes, together with the first cell 2100 and the second cell 2200, constitute a part of the first cell 2100, the density of the bipolar all-solid-state battery 2000 can be improved. Further density improvements can be achieved without providing the second positive current collector 2212.

[0141] The second porous support layer 2140 is squeezed between the first cell 2100 and the second cell 2200.

[0142] The second porous support layer 2240 may have the same structure as the second porous support layer 2140.

[0143] A separate metal current collector may be further included between the first cell 2100 and the second cell 2200 according to the present invention. That is, the metal current collector may be included between the second porous support layer 2140 and the second positive electrode 2210. The metal current collector is used to prevent lithium ions from moving directly from the first positive electrode 2110 to the second positive electrode 2210. In this case, the metal current collector may be made of the same material as the first positive electrode current collector 2112. As one embodiment, the metal current collector may be made of stainless steel, aluminum, nickel, or titanium. Alternatively, the metal current collector may be made of aluminum or stainless steel, with its surface treated with carbon, nickel, titanium, or silver.

[0144] Furthermore, the outermost part of the second cell 2200 may further include a separate metal current collector. This current collector can be a metal or a metal oxide. For example, the current collector can be made of copper, stainless steel, aluminum, nickel, titanium, or sintered carbon. Alternatively, the current collector can be made of copper or stainless steel with its surface treated with carbon, nickel, titanium, or a silver or aluminum-cadmium alloy. Additionally, the current collector may have microscale irregular patterns formed on its surface to increase adhesion to the second porous support layer 2140. The current collector can be configured in any of a variety of forms, such as a membrane, sheet, foil, mesh, porous body, foam, or nonwoven fabric.

[0145] A uniform pressing force F1 is applied to the first cell 2100 and the second cell 2200 using a clamp, and this pressing force is maintained even when using a bipolar all-solid-state battery 2000.

[0146] In the bipolar all-solid-state battery 2000 according to the present invention, such as Figure 7As shown, a lithium layer 2400 is formed after charging and discharging. The formation of the lithium layer 2400 is due to lithium deposition between the second porous support layer 2140 and the first solid electrolyte 2120 or between the second porous support layer 2240 and the second solid electrolyte 2220 through charging and discharging.

[0147] The lithium layer 2400 is charged under constant current / constant voltage (CC / CV) conditions. During this charging, the pressure F1 applied to the entire lithium secondary battery varies depending on the amount of lithium formed in the battery, the charging / discharging rate, and the charging / discharging time. This is due to the formation of the lithium layer 2400, which generates an internal pressure F2.

[0148] In the bipolar all-solid-state battery 2000 according to the present invention, the stress generated by the internal pressure F2 applied by the lithium layer 2400 is relieved by means of the second porous support layer 2140 or the second porous support layer 2240. By reducing the pore size of the second porous support layer 2140 or the second porous support layer 2240 or the second porous support layer 2240 or the second porous support layer 2140 or the second porous support layer 2240, the second porous support layer 2140 or the second porous support layer 2240 applies a uniform pressing force F1 to the entire bipolar all-solid-state battery 2000.

[0149] The present invention will be described below based on experimental examples, wherein embodiments of the invention and comparative examples based on conventional techniques will be compared with each other.

[0150] (Experimental Example 1) Experiment on the elastic force of the first porous support layer

[0151] The thickness variation of the first porous support layer of the all-solid-state battery was measured due to changes in clamp pressure during all-solid-state battery operation and / or pressure changes in lithium deposited during all-solid-state battery charging. At this time, first porous support layers #1 and #2 with similar porosity and different thicknesses, and a first porous support layer #3 with porosity and thickness different from first porous support layers #1 and #2, were used as the first porous support layers.

[0152] The first porous support layer is made of polyethylene.

[0153] The first porous support layer was stamped to a size of 2.5cm × 2.5cm. The all-solid-state battery was then pressed using a fixture at pressures of 5MPa, 10MPa, 15MPa, and 20MPa, and the thickness variation of the first porous support layer was measured at each step. The measurement results are shown in Table 1 below.

[0154] Table 1

[0155]

[0156] As pressure increases, the thickness of each first porous support layer decreases. However, for ultrathin porous support layers, such as the first porous support layer #1, the change in thickness due to pressure is small. On the other hand, for porous support layers with large thickness and high porosity, such as the first porous support layer #3, the change in thickness due to pressure is large. For the first porous support layers #1 to #3, the deformation of the porous support layers caused by changes in clamping pressure during the all-solid-state battery evaluation process and pressure changes of lithium formed during the all-solid-state battery charging process was simulated, and the thickness of the porous support layers was measured by pressing the porous support layers once, twice, three times, five times, and ten times at 5 MPa. The measurement results are shown in Table 2 below.

[0157] At this point, a porous support layer pressed at 20 MPa is used as the first porous support layer #1, and a porous support layer pressed at 10 MPa is used as the first porous support layer #2. A single sheet, a stack of two sheets, and a stack of three sheets are used as the first porous support layer #2. An unpressed porous support layer and a porous support layer pressed at 10 MPa are used as the first porous support layer #3. These first porous support layers are pressed at 5 MPa once, twice, three times, five times, and ten times.

[0158] Table 2

[0159]

[0160] To reduce the stress generated in the bipolar all-solid-state battery as desired by the present invention, the deformation range of the first porous support layer must be within its elastic range. As can be seen from Table 2, the first porous support layer according to the present invention is a thin-film type porous support layer, wherein the thickness variation of the first porous support layer (i.e., the absolute value of the deformation range of the first porous support layer) is small. In particular, for the first porous support layer #1, which is an ultra-thin porous support layer, the theoretically possible deformation range of the first porous support layer is about 4 μm. Therefore, when using a porous support layer with a small thickness, the thickness of the porous support layer does not change significantly, while the porous support layer absorbs the stress in the bipolar all-solid-state battery.

[0161] Typically, 1 mAh / cm³ is deposited during charging. 2In the case of lithium, even excluding clamp pressure, lithium is deposited on the negative electrode as a layer with a thickness of 4 μm. This invention relates to a high-capacity battery for small devices or vehicles. Generally, the capacity of the electrodes in a high-capacity battery is greater than that of the electrodes in a thin-film battery, and the thickness of lithium deposited on the negative electrode increases with increasing electrode capacity. Therefore, when using a first porous support layer with a small deformation range to alleviate stress in a bipolar all-solid-state battery, as in this invention, multiple first porous support layers can be used depending on the thickness of the deposited lithium, thereby alleviating stress in the bipolar all-solid-state battery. It can be seen that even when the first porous support layer #2 is used as a stack of two sheets or three sheets, as shown in Table 2 above, the operation is performed in the same manner as when the first porous support layer #2 is used as a single sheet.

[0162] When comparing the unpressed first porous support layer #3 with the first porous support layer #3 pressed at 10 MPa, it can be seen that when the unpressed first porous support layer #3 is pressed once at 5 MPa, the thickness of the first porous support layer decreases from 41 μm to 38 μm, and the thickness of the first porous support layer continues to decrease with the increase of the number of presses, resulting in a small deformation of the first porous support layer; however, when the first porous support layer is initially pressed at a pressure higher than the driving pressure (i.e., the first porous support layer #3 is pressed at 10 MPa), there is no change in thickness even with continuous additional pressing. Therefore, it can be seen that stacking multiple thin first porous support layers (such as the first porous support layer #2), or using a thick first porous support layer (such as the first porous support layer #3) after pressing at a pressure higher than the driving pressure, can reduce the stress of the bipolar all-solid-state battery.

[0163] (Experimental Example 2) Measurement of Thickness Increase Rate

[0164] In Experiment 2, a battery with the following structure was charged and discharged five times to calculate its thickness change rate. The initial capacity of the battery was measured by charging and discharging the battery at 60°C. The charging conditions were CC / CV (8.5V, 0.05C, 0.01C current cutoff), and the discharging conditions were CC (6V, 0.05C, 60°C). The thickness increase rate of the battery was calculated as (thickness of the battery after charging / thickness of the battery before charging) × 100, and the results are shown in Table 3 below. Furthermore, the capacity retention rate of the battery after five charge-discharge cycles was measured, and the results are shown in Table 3 below.

[0165] The battery capacity retention rate is calculated as follows.

[0166] Capacity retention rate (%) = (Capacity at the fifth cycle / Initial capacity) × 100

[0167] (Example 1-1)

[0168] NCM811(LiNi) will be used as the positive electrode active material 0.8 Co 0.1 Mn 0.1 O2), aragonite (Li6PS5Cl) as the solid electrolyte, carbon as the conductive agent, and PTFE as the binder are dispersed in anisole at a weight ratio of 77.5:19.5:1.5:1.5 and stirred to prepare a positive electrode slurry. The positive electrode slurry is applied to an aluminum current collector with a thickness of 15 μm by a doctor blade coating and dried under vacuum at 100 °C for 12 hours to produce a current collector with a capacity of 2 mAh / cm³. 2 The positive pole.

[0169] Argyrodite (Li6PS5Cl) and PTFE, used as binders, were mixed in a weight ratio of 95:5 to create a solid electrolyte layer.

[0170] A nickel electrode with a thickness of 11 μm was used as the negative electrode current collector.

[0171] Figure 5 This is a cross-sectional view of the bipolar all-solid-state battery 1000 used in Experiment Example 2.

[0172] A solid-state battery according to Experimental Example 2 is formed by stacking the first cell 1100 and the second cell 1200 with a first porous support layer 1300 inserted between them. The first cell 1100 is configured to have a structure in which a first positive electrode 1110, a first solid electrolyte 1120, and a negative electrode consisting only of a first negative current collector 1132 are stacked. The first positive electrode 1110 has a first positive electrode active material 1111 formed on one surface of the first positive current collector 1112. The second cell 1200 is configured to have a structure in which a negative electrode consisting only of a second negative current collector 1232 is stacked. In this case, the first positive electrode active material 1111 is stacked facing the first solid electrolyte 1120, and the second positive electrode active material 1211 is stacked in the same manner. At this time, the first positive current collector 1112 faces the fixture JIG, and the second positive current collector 1212 faces the first porous support layer 1300.

[0173] The first porous support layer 1300 used in Embodiment 1-1 of the present invention is a stack of three sheets of the first porous support layer #2 pressed at 10 MPa.

[0174] (Examples 1-2)

[0175] The all-solid-state battery was manufactured and evaluated in the same manner as in Example 1-1, but the difference from Example 1-1 was that a single sheet of the first porous support layer #2 pressed at 10 MPa was used as the first porous support layer 1300.

[0176] (Examples 1-3)

[0177] The all-solid-state battery was manufactured and evaluated in the same manner as in Example 1-1, but unlike Example 1-1, a battery with a capacity of 3 mAh / cm² was used. 2 The positive electrode of the capacity.

[0178] (Comparative Example 1-1)

[0179] The all-solid-state battery was manufactured and evaluated in the same manner as in Example 1-1, but unlike Example 1-1, no first porous support layer was applied.

[0180] (Comparative Examples 1-2)

[0181] The all-solid-state battery was manufactured and evaluated in the same manner as in Example 1-1, but the difference from Example 1-1 was that a single sheet of the first porous support layer #2 pressed at 20 MPa was used as the first porous support layer 1300.

[0182] (Comparative Examples 1-3)

[0183] The all-solid-state battery was manufactured and evaluated in the same manner as in Example 1-1, but the difference from Example 1-1 is that a single sheet of the first porous support layer #3 was used as the first porous support layer 1300.

[0184] Table 3

[0185] Thickness increase rate (%) after five charging cycles Retention rate (%) after 5 cycles Example 1-1 0.2 94.0 Examples 1-2 0.5 95.0 Examples 1-3 0.7 94.5 Comparative Example 1-1 7.0 89.6 Comparative Examples 1-2 6.8 91.0 Comparative Examples 1-3 4.2 89.8

[0186] As shown in Table 3, when the elastic force of the first porous support layer is greater than the battery driving pressure (as in Examples 1-1 to 1-3 of this invention), the thickness change caused by lithium formed during charging is absorbed by the first porous support layer, thereby alleviating the stress of the all-solid-state battery. It can be seen that this mitigation of thickness change continues even after five charge-discharge cycles. Theoretically, the deformation of the first porous support layer can be calculated based on its thickness and porosity, and it can be seen that even when the capacity of the positive electrode is 3 mAh / cm³, the deformation is still significant. 2 In cases such as those described in Examples 1-3, i.e., even when the capacity of the positive electrode is increased, there is almost no increase in thickness during the charge and discharge process.

[0187] In comparison, it can be seen that in Comparative Example 1-1, which does not use a first porous support layer, the thickness of the all-solid-state battery is increased, thereby increasing the internal resistance of the all-solid-state battery. Therefore, the lifespan of the all-solid-state battery is shorter than that of the all-solid-state batteries according to Examples 1-1 to 1-3. Furthermore, it can be seen that in Comparative Example 1-2, where a first porous support layer is configured such that the displacement of the first porous support layer is less than the increased thickness of the first porous support layer, and in Comparative Example 1-3, where the elastic force of the first porous support layer is low and thus the thickness of the first porous support layer continuously changes, the effect is not significant even when using the first porous support layer. Therefore, it can be seen that the elastic range of the first porous support layer must be greater than the deformation range of the first porous support layer caused by deposited lithium.

[0188] That is, due to the all-solid-state battery's capacity per unit (i.e., 1mAh / cm³) 2 Lithium with a thickness of 4 μm is deposited, so the deformation range of the first porous support layer can be calculated based on the thickness and porosity of the first porous support layer, and the first porous support layer can be stacked to have one or more layers.

[0189] (Experimental Example 3) Experiment on the elastic force of the second porous support layer

[0190] Two types of nickel (Ni) foam (Ni foam #1 and Ni foam #2) were selected as the second porous support layer for use as a porous current collector in all-solid-state batteries. The second porous support layer was stamped to a size of 2.0 cm × 2.0 cm and pressed sequentially at pressures of 5 MPa, 10 MPa, 15 MPa, 25 MPa, and 50 MPa, with the thickness variation of the second porous support layer measured at each step. The measurement results are shown in Table 4 below.

[0191] [Table 4]

[0192]

[0193] The thicknesses of nickel foam #1 and nickel foam #2 gradually decrease with increasing pressure. After being pressed at 50 MPa, nickel foam #1 has a thickness of 165 μm and a porosity of 48%, while nickel foam #2 has a thickness of 109 μm and a porosity of 83%.

[0194] To simulate the deformation of the second porous support layer caused by variations in clamping pressure during all-solid-state battery evaluation and pressure variations due to lithium formation during all-solid-state battery charging, the second porous support layer was repeatedly pressed at 5 MPa, then repeatedly pressed at 10 MPa, and subsequently pressed at 15 MPa and 25 MPa after the 10 MPa pressing. The thickness of the second porous support layer was measured after each pressing. The measurement results are shown in Tables 5 and 6 below.

[0195] At this point, nickel foam #1, nickel foam #1 pressed at 50 MPa, and nickel foam #2 pressed at 50 MPa are used as the second porous support layer.

[0196] [Table 5]

[0197]

[0198] Table 6

[0199]

[0200]

[0201] For the unprocessed nickel foam #1, the thickness of the second porous support layer continuously decreases when it is pressed sequentially at 5 MPa. This thickness reduction occurs because the pressure exceeds the elastic force of the second porous support layer, resulting in continuous plastic deformation. In particular, the strain continuously increases when the pressure increases to 10 MPa or 15 MPa. That is, when manufacturing a battery using the second porous support layer, the thickness of the second porous support layer decreases due to the increased pressure caused by lithium deposition during continuous charging and discharging, and the thickness does not recover even when lithium deposition is alleviated. Since the thickness of the second porous support layer does not recover as described above, the deposited lithium migrates to the positive electrode during discharge, thereby reducing the thickness of the lithium layer. Consequently, the contact between the second porous support layer, the solid electrolyte, and the positive electrode decreases, increasing the interfacial resistance in the battery and thus degrading the performance of the all-solid-state battery.

[0202] In comparison, it can be seen that the thickness of nickel foam #1 and nickel foam #2, pressed at 50 MPa, remains unchanged even after being pressed several times at 5 MPa. This is because nickel foam #1 and nickel foam #2, pressed at 50 MPa, have already been compressed and deformed, thus increasing their strength. Therefore, greater pressure is required to deform the second porous support layer. As can be seen from Tables 2 and 3 above, nickel foam #1 and nickel foam #2, pressed at 50 MPa, do not deform even at 25 MPa, thus fully withstanding the pressure generated during the all-solid-state battery operation. As described above, when the second porous support layer does not deform, its initial thickness and shape can remain unchanged during charging and discharging. Furthermore, when using the second porous support layer, uniform contact is maintained between the positive electrode, the solid electrolyte, and the second porous support layer, thereby preventing battery performance degradation. At this point, it is more effective to use a support layer that can maintain its shape when deformed under pressure (i.e., a support layer with high shape retention force) as the second porous support layer.

[0203] Although not described in the detailed description section of this specification, the second porous support layer can be applied to a wide variety of other components used in batteries and can be made from all materials suitable for batteries. Furthermore, in addition to all-solid-state batteries, the second porous support layer can also be applied to batteries using electrolytes or any products capable of storing electricity.

[0204] (Experimental Example 4) Measurement of Thickness Increase Rate

[0205] In Experiment 4, an all-solid-state battery with the following structure was charged and discharged five times to calculate its thickness change rate. The initial capacity of the battery was measured by charging and discharging the battery at 60°C. The charging conditions were CC / CV (8.5V, 0.05C, 0.01C current cutoff), and the discharging conditions were CC (6V, 0.05C, 60°C). The thickness increase rate of the battery was calculated as (thickness of the battery after charging / thickness of the battery before charging) × 100, and the calculation results are shown in Table 4 below.

[0206] (Example 2-1)

[0207] NCM811(LiNi) will be used as the positive electrode active material 0.8 Co 0.1 Mn 0.1 O2), aragonite (Li6PS5Cl) as the solid electrolyte, carbon as the conductive agent, and PTFE as the binder are dispersed in anisole at a weight ratio of 77.5:19.5:1.5:1.5 and stirred to prepare a positive electrode slurry. The positive electrode slurry is applied to an aluminum current collector with a thickness of 15 μm by a doctor blade coating and dried under vacuum at 100 °C for 12 hours to produce a current collector with a capacity of 4 mAh / cm³. 2 The positive electrode is used as the outermost positive electrode.

[0208] Argyrodite (Li6PS5Cl) and PTFE, used as binders, were mixed in a weight ratio of 95:5 to create a solid electrolyte layer.

[0209] In practical application, nickel foam #1 pressed at 50 MPa was used as the second porous support layer in Experiment Example 3.

[0210] By dispersing and stirring NCM811 (LiNi 0.8 Co 0.1 Mn 0.1 A positive electrode slurry obtained from O2 as the positive electrode active material, argyrodite (Li6PS5Cl) as the solid electrolyte, carbon as the conductive agent, and PTFE as the binder are used in anisole in a weight ratio of 77.5:19.5:1.5:1.5 to form a positive electrode active material on one surface facing the second porous support layer.

[0211] In Embodiment 2-1 of the present invention, nickel is used as the outermost negative electrode current collector.

[0212] Figure 8 This is a cross-sectional view of the bipolar all-solid-state battery 2000 used in Experimental Example 4 of the present invention.

[0213] An all-solid-state battery according to Experimental Example 4 is formed by stacking a first cell 2100 and a second cell 2200. The first cell 2100 is configured to have a structure in which a first positive electrode 2110, a first solid electrolyte 2120, and a second porous support layer 2140 are stacked. The first positive electrode 2110 has a first positive electrode active material 2111 formed on one surface of a first positive electrode current collector 2112. The second cell 2200 is configured to have a structure in which a second positive electrode active material 2211, a second solid electrolyte 2220, and a second negative electrode current collector 2232 are stacked. At this time, the first positive electrode active material 2111 faces the first solid electrolyte layer 2120. The all-solid-state battery is pressed by a jig, with the first positive electrode current collector 2112 and the second negative electrode current collector 2232 facing the jig.

[0214] Figure 8 The all-solid-state battery is manufactured using materials according to Example 2-1.

[0215] The clamps are tightened to apply a force of 5 MPa to the all-solid-state battery, and then charging and discharging are performed.

[0216] (Example 2-2)

[0217] The all-solid-state battery was manufactured and evaluated in the same manner as in Example 2-1, but the difference from Example 2-1 was that nickel foam #2 pressed at 50 MPa was used as the second porous support layer.

[0218] (Examples 2-3)

[0219] The all-solid-state battery was manufactured and evaluated in the same manner as in Example 2-1, except that the capacity of the positive electrode was 6 mAh / cm³. 2 Furthermore, nickel foam #2, pressed at 50 MPa, is used as a second porous support layer.

[0220] (Comparative Example 2-1)

[0221] The all-solid-state battery was manufactured and evaluated in the same manner as in Example 2-1, but unlike Example 2-1, a nickel foil with a thickness of 10 μm was used as the second porous support layer.

[0222] (Comparative Example 2-2)

[0223] The all-solid-state battery was manufactured and evaluated in the same manner as in Example 2-1, except that the capacity of the positive electrode was 6 mAh / cm³. 2 A 10μm thick nickel foil was used as the second porous support layer.

[0224] Table 7

[0225]

[0226] As shown in Table 7, when the elastic force of the second porous support layer is greater than the battery driving pressure (as in Examples 2-1 to 2-3 of this invention), the thickness change caused by lithium formed during charging is absorbed by the second porous support layer, thereby alleviating the stress in the all-solid-state battery with the help of the second porous support layer. It can be seen that this alleviation of thickness change continues even after five charge-discharge cycles. This indicates that the deformation of the nickel foam is more significant than the stress due to the increased thickness of lithium deposited during charging and the elastic force of the second porous support layer. Theoretically, the deformation of the second porous support layer can be predicted based on its thickness and porosity, and it can be seen that even with a positive electrode capacity of 6 mAh / cm², the deformation is still significant. 2 In the case of (as in Examples 2-3, i.e., even when the positive electrode capacity increases), the thickness of the second porous support layer is 109 μm and the porosity of the second porous support layer is 83%, i.e. there is almost no increase in thickness during the charging and discharging process.

[0227] In comparison, it can be seen that in Comparative Example 2-1, which uses ordinary nickel foil, the increase in thickness caused by lithium deposition even in a single charge is not mitigated, resulting in an 11.4% increase in thickness. This rate of thickness change increases with each additional charge cycle. Furthermore, it can be seen that in Comparative Example 2-2, where the capacity of the positive electrode is increased, the rate of thickness change further increases to 15.8%, thus the stress caused by lithium deposition is not alleviated. Therefore, from the above results, it can be seen that the second porous support layer according to the present invention can effectively minimize the rate of thickness change caused by battery charging and discharging in all-solid-state batteries operating based on a lithium plating / stripping mechanism.

[0228] Furthermore, the present invention provides a battery module including a bipolar all-solid-state battery, a battery pack including a bipolar all-solid-state battery, and an apparatus including the battery pack. The battery module, battery pack, and apparatus are well known in the art to which this invention pertains, and therefore their detailed description will be omitted.

[0229] For example, the device may be a laptop computer, netbook computer, tablet computer, mobile phone, MP3 player, wearable electronic device, power tool, electric vehicle (EV), hybrid electric vehicle (HEV), plug-in hybrid electric vehicle (PHEV), electric bicycle (E-bike), electric scooter (E-scooter), electric golf cart, or energy storage system. However, the invention is not limited thereto.

[0230] Those skilled in the art will understand that, based on the above description, various applications and modifications within the scope of this invention are possible.

[0231] (Explanation of reference numerals in the attached diagram)

[0232] 10, 1000, 2000: Bipolar all-solid-state batteries

[0233] 100, 1100, 2100: First unit cell

[0234] 110, 1110, 2110: First positive electrode

[0235] 111, 1111, 2111: First positive electrode active material

[0236] 112, 1112, 2112: First positive electrode current collector

[0237] 120, 1120, 2120: First solid electrolyte

[0238] 130, 1130: First negative electrode

[0239] 131, 1131: First negative electrode active material

[0240] 132, 1132: First negative electrode current collector

[0241] 2140, 2240: Second porous support layer

[0242] 200, 1200, 2200: Second unit cells

[0243] 210, 1210, 2210: Second positive electrode

[0244] 211, 1211, 2211: Second positive electrode active materials

[0245] 212, 1212, 2212: Second positive electrode current collector

[0246] 220, 1220, 2220: Second solid electrolyte

[0247] 230, 1230: Second negative electrode

[0248] 231, 1231: Second negative electrode active material

[0249] 232, 1232: Second negative electrode current collector

[0250] 300: Bipolar electrode

[0251] 1300: First porous support layer

[0252] 400, 1400, 2400: Lithium layer

[0253] F1: Press pressure

[0254] F2: Internal Pressure

[0255] m: Thickness before pressing

[0256] M: Thickness after pressing

[0257] JIG: Fixture

[0258] Industrial applicability

[0259] This invention relates to a bipolar all-solid-state battery including a porous support layer, and more specifically to a bipolar all-solid-state battery configured such that (a) two or more cell units, each including a positive electrode, a solid electrolyte, and a negative electrode, are connected in series with each other, and a first porous support layer is disposed at the interface between the two or more cell units; or (b) two or more cell units, each including a positive electrode, a solid electrolyte, and a second porous support layer, are connected in series with each other, and thus the invention has industrial applicability.

Claims

1. A bipolar all-solid-state battery, said bipolar all-solid-state battery being configured such that: Each cell comprises two or more unit cells connected in series, including a positive electrode, a solid electrolyte, and a second porous support layer. The surface of the second porous support layer facing the solid electrolyte serves as the negative electrode, and the surface of the second porous support layer facing the positive electrode serves as a separator. The second porous support layer is configured such that its thickness decreases when pressure is applied and recovers when the pressure is released, thereby adjusting the stress in the bipolar all-solid-state battery. The second porous support layer includes polyolefin-based resin, polyethylene terephthalate, polycyclic olefin, polyethersulfone, polyamide, polyimide, polyimide-amide, polyarylamide, or polytetrafluoroethylene.

2. The bipolar all-solid-state battery according to claim 1, wherein, The second porous support layer includes a lithium anode or a negative electrode current collector.

3. The bipolar all-solid-state battery according to claim 2, wherein, The negative electrode current collector is a metal or a metal oxide.

4. The bipolar all-solid-state battery according to claim 2, wherein, The lithium anode or the anode current collector does not include a separate active material layer.

5. The bipolar all-solid-state battery according to claim 1, wherein, The pressure is generated as a result of lithium ions moving from the positive electrode to the negative electrode and depositing between the second porous support layer and the solid electrolyte.

6. The bipolar all-solid-state battery according to claim 5, wherein, The thickness of the second porous support layer is greater than the thickness of the deposited lithium.

7. The bipolar all-solid-state battery according to claim 1, wherein, The second porous support layer adjusts the stress in proportion to its thickness and porosity.

8. The bipolar all-solid-state battery according to claim 1, wherein, The positive electrode includes: Positive current collector; and Positive electrode active material applied to one surface of the positive electrode current collector.

9. The bipolar all-solid-state battery according to claim 8, wherein, The positive electrode active material faces the solid electrolyte, and The positive current collector faces the second porous support layer.

10. The bipolar all-solid-state battery according to claim 1, wherein, In the positive electrode, the positive electrode disposed between the second porous support layer and the solid electrolyte is composed only of positive electrode active material, and At this point, the outermost positive electrode includes a positive current collector and a positive active material applied to the surface of the positive current collector facing the solid electrolyte.

11. The bipolar all-solid-state battery according to claim 1, wherein, The two or more cell units are housed in a pouch-shaped battery casing.

12. The bipolar all-solid-state battery according to claim 1, wherein, The two or more cell units are pressed by external clamps during their charging and discharging processes.

13. The bipolar all-solid-state battery according to claim 1, wherein, A bipolar all-solid-state battery, in which two or more cell units, each comprising the positive electrode, the solid electrolyte, and the second porous support layer, are connected in series, is configured such that one or more cell stacks, each comprising the second porous support layer, positive electrode active material, and solid electrolyte, are repeatedly disposed between the outermost positive electrode and the solid electrolyte facing the outermost positive electrode and the outermost negative electrode.

14. The bipolar all-solid-state battery according to claim 1, wherein, A bipolar all-solid-state battery, in which two or more cell units, each comprising the positive electrode, the solid electrolyte, and the second porous support layer, are connected in series, is configured such that one or more cell stacks, each comprising the second porous support layer, a positive electrode current collector, a positive electrode active material, and a solid electrolyte, are repeatedly disposed between the outermost positive electrode and the solid electrolyte facing the outermost positive electrode and the outermost negative electrode.

15. The bipolar all-solid-state battery according to claim 1, wherein, The polyolefin-based resin is polyethylene, polypropylene, polybutene, or polyvinyl chloride, or a mixture or copolymer thereof.

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