Polymer pad for all-solid-state battery, all-solid-state battery system comprising same, and manufacturing method therefor

Abstract

The present invention relates to a polymer pad for an all-solid-state battery, an all-solid-state battery system comprising same, and a manufacturing method therefor. More specifically, the polymer pad for an all-solid-state battery comprises crosslinked polyurethane having a melting point (Tm) of 170°C or higher in a differential scanning calorimetry (DSC) analysis, and has a thickness of 1 mm to 1.5 cm.

Description

Polymer pad for all-solid-state batteries, all-solid-state battery system including the same, and method for manufacturing the same

[0001] The present invention relates to a polymer pad for an all-solid-state battery, an all-solid-state battery system including the same, and a method for manufacturing the same.

[0002] Recently, driven by industrial demands, the development of batteries with high energy density and safety is actively underway. For example, lithium-ion batteries are being commercialized not only in the fields of information and communication devices but also in the automotive sector. In the automotive sector, safety is considered particularly important because it is directly related to human life.

[0003] Recently, all-solid-state batteries in which liquid electrolytes are replaced with solid electrolytes have been proposed. By not using flammable organic dispersion media, all-solid-state batteries can significantly reduce the likelihood of fire or explosion in the event of a short circuit. Therefore, these all-solid-state batteries can offer significantly higher safety compared to lithium-ion batteries that use liquid electrolytes.

[0004] The problem that the present invention aims to solve is to provide a polymer pad for an all-solid-state battery that can pressurize a cell stack during charging and discharging, accommodate volume expansion of the cell stack, and maintain internal pressure of the cell stack by uniformly applying surface pressure to the cell stack.

[0005] Another problem that the present invention aims to solve is to provide a lightweight all-solid-state battery system that not only has excellent charge / discharge efficiency and a long lifespan, but also allows for efficient utilization of internal space.

[0006] Another problem that the present invention aims to solve is to provide a method for manufacturing a polymer pad for an all-solid-state battery having the characteristics described above.

[0007] A polymer pad for an all-solid-state battery according to one embodiment of the present invention has a melting point (T) when analyzed by differential scanning calorimetry (DSC). mIt includes a cross-linked polyurethane with a temperature of 170°C or higher, and may have a thickness of 1 mm to 1.5 cm.

[0008] A solid-state battery system according to one embodiment of the present invention comprises: a cell stack including a unit cell and an elastic pad; end plates sandwiching the cell stack; a polymer pad located between at least one of the cell stack and the end plates; and a fastening portion, wherein the polymer pad may be the polymer pad described above.

[0009] A method for manufacturing a polymer pad for an all-solid-state battery according to one embodiment of the present invention comprises injecting a thermoplastic polyurethane and a crosslinking agent into an injection molding machine and injection molding, wherein the crosslinking agent may include a plurality of isocyanate functional groups.

[0010] A polymer pad for an all-solid-state battery according to one embodiment of the present invention can pressurize a cell stack during charging and discharging of an all-solid-state battery, can accommodate volume expansion of the cell stack, and can maintain internal pressure of the cell stack by uniformly pressing the cell stack with surface pressure. In addition, the polymer pad for an all-solid-state battery can reduce or omit washer springs used in an all-solid-state battery system. The polymer pad for an all-solid-state battery can replace washer springs.

[0011] An all-solid-state battery system according to one embodiment of the present invention can have excellent charge / discharge efficiency and a long lifespan. The all-solid-state battery system can be made lighter by reducing or omitting washer springs. In addition, the all-solid-state battery system can efficiently utilize internal space and increase capacity.

[0012] A method for manufacturing a polymer pad for an all-solid-state battery according to one embodiment of the present invention can easily manufacture a polymer pad for an all-solid-state battery having the characteristics described above. In addition, the method for manufacturing a polymer pad for an all-solid-state battery can mass-produce the polymer pad described above.

[0013] FIG. 1 is a cross-sectional view of an all-solid-state battery according to one embodiment of the present invention.

[0014] FIG. 2 is a plan view of an all-solid-state battery according to another embodiment of the present invention.

[0015] Figure 3 is a cross-sectional view along the line AA' of Figure 2.

[0016] FIG. 4 is a cross-sectional view of an all-solid-state battery according to another embodiment of the present invention.

[0017] FIG. 5 is a cross-sectional view of an all-solid-state battery according to another embodiment of the present invention.

[0018] FIG. 6 is a cross-sectional view of an all-solid-state battery according to another embodiment of the present invention.

[0019] FIG. 7 is a cross-sectional view of an all-solid-state battery according to another embodiment of the present invention.

[0020] FIG. 8 is a cross-sectional view of an all-solid-state battery system according to one embodiment of the present invention.

[0021] FIG. 9 is a cross-sectional view of an all-solid-state battery system according to another embodiment of the present invention.

[0022] FIG. 10 is a cross-sectional view of an all-solid-state battery system according to another embodiment of the present invention.

[0023] FIG. 11 is a cross-sectional view of an all-solid-state battery system according to another embodiment of the present invention.

[0024] FIG. 12 is a cross-sectional view of an all-solid-state battery system according to another embodiment of the present invention.

[0025] FIG. 13 is a cross-sectional view of an all-solid-state battery system according to another embodiment of the present invention.

[0026] FIG. 14 is an enlarged view illustrating a polymer pad for an all-solid-state battery according to embodiments of the present invention.

[0027] FIG. 15 is an enlarged view illustrating a polymer pad for an all-solid-state battery according to one embodiment of the present invention.

[0028] FIGS. 16a, FIGS. 16b, and FIGS. 16c are FT-IR results for polymer pads for all-solid-state batteries according to Examples 1 and 2 and Comparative Example 1.

[0029] Figure 17 is the DSC result for polymer pads for all-solid-state batteries according to Examples 1 and 2 and Comparative Example 1.

[0030] Figure 18 shows the TGA results for polymer pads for all-solid-state batteries according to Examples 1 and 2 and Comparative Example 1.

[0031] FIGS. 19a and 19b are the results of compression tests on polymer pads for all-solid-state batteries according to Examples 1 and 2 and Comparative Example 1.

[0032] FIG. 20 is the result of a compression test for an all-solid-state battery system according to Examples 1 and 2 and Comparative Example 1.

[0033] Figure 21 is the result of a computer simulation for an all-solid-state battery system according to Example 1.

[0034] Figure 22 is the result of a computer simulation for an all-solid-state battery system with a washer spring added to Example 1.

[0035] Figure 23 is the result of a computer simulation for an all-solid-state battery system according to Comparative Example 2.

[0036] Figure 24 shows the discharge capacity results of the all-solid-state battery system according to Example 2 and Comparative Example 2.

[0037] Figure 25 shows the charge-discharge efficiency results of the all-solid-state battery system according to Example 2 and Comparative Example 2.

[0038] Figure 26 shows the life evaluation results of the all-solid-state battery system according to Example 2 and Comparative Example 2.

[0039] FIG. 27 is an image of the negative electrode layer obtained by disassembling the cell stack immediately after evaluating the lifespan of the all-solid-state battery system according to Example 2.

[0040] FIG. 28 is an image of the negative electrode layer obtained by disassembling the cell stack immediately after evaluating the lifespan of the all-solid-state battery system according to Comparative Example 2.

[0041] In order to fully understand the structure and effects of the present invention, preferred embodiments of the present invention are described with reference to the attached drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various forms and various modifications can be made. The description of these embodiments is provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention.

[0042] In this specification, when a component is described as being on another component, it means that it may be formed directly on the other component or that a third component may be interposed between them. Additionally, in the drawings, the thicknesses of the components are exaggerated for the effective description of the technical content. Throughout the specification, parts indicated by the same reference numeral represent the same components.

[0043] The embodiments described herein will be described with reference to cross-sectional and / or plan views, which are exemplary illustrations of the invention. In the drawings, the thicknesses of films and regions are exaggerated for effective description of the technical content. Accordingly, the regions illustrated in the drawings are schematic in nature, and the shapes of the regions illustrated in the drawings are intended to illustrate specific forms of regions of the device and are not intended to limit the scope of the invention. Although terms such as first, second, third, etc., have been used to describe various components in the various embodiments of this specification, these components should not be limited by such terms. These terms are used merely to distinguish one component from another. The embodiments described and illustrated herein also include their complementary embodiments.

[0044] The terms used herein are for describing the embodiments and are not intended to limit the invention. In this specification, the singular form includes the plural form unless specifically stated otherwise in the text. As used herein, 'comprises' and / or 'comprising' do not exclude the presence or addition of one or more other components to the mentioned components.

[0045] In this specification, "combination of these" may mean a mixture of components, a laminate, a composite, a copolymer, an alloy, a blend, and a reaction product, etc.

[0046] Unless otherwise defined in this specification, the particle size may be the average particle size. Additionally, the particle size refers to the average particle size (D50), which means the diameter of the particle whose cumulative volume in the particle size distribution is 50% by volume. The average particle size (D50) may be measured by methods widely known to those skilled in the art, for example, by measuring with a particle size analyzer, or by measuring with a transmission electron microscope (TEM) image or a scanning electron microscope (SEM) image. Alternatively, the average particle size (D50) value may be obtained by measuring using a measuring device utilizing dynamic light-scattering, performing data analysis to count the number of particles for each particle size range, and then calculating from this. Alternatively, it may be measured using a laser diffraction method. When measuring by laser diffraction, more specifically, after dispersing the particles to be measured in a dispersion medium, they are introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac MT 3000) and irradiated with ultrasound of about 28 kHz at an output of 60 W, and then the average particle size (D50) at 50% of the particle size distribution in the measuring device can be calculated.

[0047] In this specification, each of the phrases such as “A or B”, “at least one of A and B”, “at least one of A or B”, “A, B or C”, “at least one of A, B and C”, and “at least one of A, B, or C” may include any one of the items listed together in the corresponding phrase, or all possible combinations thereof.

[0048]

[0049] FIG. 1 is a cross-sectional view of an all-solid-state battery according to one embodiment of the present invention.

[0050] Referring to FIG. 1, a unit cell (CEL) of an all-solid-state battery according to the present invention may include a positive electrode layer (100), a negative electrode layer (200) facing the positive electrode layer (100), and a solid electrolyte layer (300) disposed between the positive electrode layer (100) and the negative electrode layer (200). However, not limited thereto, the unit cell (CEL) may further include an additional functional layer, such as an adhesion enhancing layer, disposed between the positive electrode layer (100) and the solid electrolyte layer (300) or between the negative electrode layer (200) and the solid electrolyte layer (300).

[0051] An anode layer (100) according to one embodiment of the present invention may include an anode current collector (110) and an anode active material layer (120) disposed on the anode current collector (110). The anode active material layer (120) may include an anode active material, a solid electrolyte, a conductive material, and a binder.

[0052] The positive current collector (110) can provide a reference surface on which the positive active material layer (120) is placed. The positive current collector (110) may include, for example, a plate or foil comprising indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof.

[0053] Meanwhile, unlike as illustrated in FIG. 1, the positive current collector (110) may be omitted in one embodiment of the present invention. Although not illustrated, a carbon layer with a thickness of 0.1 μm to 4 μm may be further disposed between the positive current collector (110) and the positive active material layer (120) to increase the bonding strength between the positive current collector (110) and the positive active material layer (120).

[0054] The positive active material of the positive active material layer (120) may include a material capable of reversibly absorbing and desorbing lithium ions. The positive active material may include a plurality of particles. The positive active material may include, for example, lithium transition metal oxides such as lithium cobalt oxide (LCO), lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide (NCA), lithium nickel cobalt manganese oxide (NCM), lithium manganate, and lithium iron phosphate, nickel sulfide, copper sulfide, lithium sulfide, iron oxide, or vanadium oxide, but is not necessarily limited to these. Each positive active material may be a single material or a mixture of two or more materials.

[0055] Lithium transition metal oxides are, for example, Li a A 1-b B b D2(0.90≤a≤1, 0≤b≤0.5), Li a E 1-b B b O 2-c D c (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05), LiE 2-b B b O 4-c D c (0≤b≤0.5, 0≤c≤0.05), Li a Ni 1-b-c Co b B c D α (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2), Li a Ni 1-b-c Co b B c O 2-α F α (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2), Li a Ni 1-b-cMn b B c D α (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α≤2), Li a Nor 1-b-c Mn b B c O 2-α F α (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2), Li a Nor b E c G d O2(0.90≤a≤1, 0≤b≤0.9, 0≤c≤0.5, 0.001≤d≤0.1), Li a Nor b Co c Mn d GeO2(0.90≤a≤1, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0.001≤e≤0.1), Li a NiG b O2(0.9≤a≤1, 0.001≤b≤0.1), Li a CoG b O2(0.90≤a≤1, 0.001≤b≤0.1), Li a MnG b O2(0.90≤a≤1, 0.001≤b≤0.1), Li a Mn2GbO4(0.90≤a≤1, 0.001≤b≤0.1), QO2, QS2, LiQS2, V2O5, LiV2O5, LiIO2, LiNiVO4, Li 3-f J2(PO4)3(0≤f≤2), Li 3-fIt is a compound represented by any one of Fe2(PO4)3 (0≤f≤2) or LiFePO4. In such compounds, the uppercase “A” is Ni, Co, Mn, or a combination thereof; the uppercase “B” is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; the uppercase “D” is O, F, S, P, or a combination thereof; the uppercase “E” is Co, Mn, or a combination thereof; the uppercase “F” is F, S, P, or a combination thereof; the uppercase “G” is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; the uppercase “Q” is Ti, Mo, Mn, or a combination thereof; the uppercase “I” is Cr, V, Fe, Sc, Y, or a combination thereof; and the uppercase “J” is V, Cr, Mn, Co, Ni, Cu, or a combination thereof.

[0056] The positive electrode active material may include, for example, a lithium salt of a transition metal oxide having a layered rock salt type structure among the lithium transition metal oxides described above. The "layered rock salt type structure" is, for example, a cubic rock salt type structure. <111> It is a structure in which oxygen and metal atomic layers are alternately and regularly arranged in a specific direction, thereby forming a two-dimensional plane for each atomic layer. The "cubic rock salt type structure" represents a sodium chloride (NaCl) type structure, which is a type of crystal structure; specifically, it exhibits a structure in which face-centered cubic lattices (fcc) formed by cations and anions, respectively, are offset from each other by half the ridge of the unit lattice. Lithium transition metal oxides having such a layered rock salt type structure are, for example, LiNi x Co y Al z O2(NCA) or LiNi x Co y Mn zO2(NCM) (0 <x<1,0<y<1, 0<z<1, x+y+z=1) 등의 삼원계 리튬전이금속산화물일 수 있다. 양극 활물질(PAM)이 층상암염형 구조를 갖는 삼원계 리튬전이금속산화물을 포함하는 경우, 단위 셀(CEL)의 에너지 밀도가 커지고 열안정성이 향상될 수 있다.

[0057] The aforementioned compound contained in the positive electrode active material may be covered by a coating layer (not shown). The positive electrode active material may also be a mixture of the aforementioned compound and the compound to which the coating layer is added. Meanwhile, the coating layer added to the surface of the positive electrode active material may include, for example, oxides, hydroxides, oxyhydroxides, oxycarbonates, or hydroxycarbonates of the following coating elements. The compounds forming this coating layer are amorphous or crystalline. The coating elements included in the coating layer may include Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or mixtures thereof. The coating layer may include, for example, Li2O-ZrO2 (LZO). The method for forming the coating layer is selected within a range that does not adversely affect the physical properties of the positive electrode active material (PAM). The method for forming the coating layer is, for example, spray coating or immersion.

[0058] When the cathode active material is a ternary lithium transition metal oxide, such as NCA or NCM, containing nickel (Ni), it is possible to increase the capacity density of the unit cell (CEL) and reduce the metal leaching of the cathode active material in the charged state. Consequently, the cycle characteristics of the unit cell (CEL) in the charged state are improved. Meanwhile, "cycle characteristics" refers to the degree of degradation of the unit cell (CEL) due to charging and discharging; a unit cell (CEL) with high cycle characteristics experiences less degradation due to charging and discharging, while a unit cell (CEL) with low cycle characteristics may experience greater degradation due to charging and discharging.

[0059] The positive active material may have particle shapes such as, for example, spheres or ellipsoids. The particle size and content of the positive active material are not particularly limited.

[0060] The solid electrolyte of the positive active material layer (120) may have a particle shape. The solid electrolyte may be dispersed among the positive active materials. The solid electrolyte may include a sulfide-based solid electrolyte with excellent lithium ion conductivity characteristics. Sulfide-based solid electrolytes are, for example, Li2S-P2S5, Li2S-P2S5-LiX (where X is a halogen element), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (m, n are positive numbers, uppercase “Z” is one of Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p, q are positive numbers, uppercase “M” is one of P, Si, Ge, B, Al, Ga, In), Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), or Li 7-x PS 6-x I x It may include at least one of (0≤x≤2).

[0061] Sulfide-based solid electrolytes are, for example, Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), or Li 7-x PS6-x I x It may be an argyrodite-type compound comprising at least one of (0≤x≤2). In particular, the sulfide-based solid electrolyte may be an argyrodite-type compound comprising at least one of Li6PS5Cl, Li6PS5Br, or Li6PS5I.

[0062] Alternatively, sulfide-based solid electrolytes are Li 7-a M a PS 6-c X c It may be an argyrodite-type compound containing (0≤a≤2, 0≤c≤2). Here, X may be F, Br, Cl, I, or a combination thereof. M may be candium (Sc), yttrium (Y), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W), manganese (Mn), technetium (Tc), rhenium (Re), iron (Fe), ruthenium (Ru), osmium (Os), cobalt (Co), rhodium (Rh), iridium (Ir), nickel (Ni), palladium (Pd), platinum (Pt), copper (Cu), silver (Ag), gold (Au), zinc (Zn), cadmium (Cd), mercury (Hg), aluminum (Al), gallium (Ga), indium (In), thallium (Tl), silicon (Si), germanium (Ge), tin (Sn), lead (Pb), arsenic (As), antimony (Sb), bismuth (Bi), or a combination thereof.

[0063] The density of the azyrodite-type solid electrolyte (PSE) may be 1.5 g / cc to 2.0 g / cc. By having a density of 1.5 g / cc or higher for the azyrodite-type solid electrolyte (PSE), the internal resistance of the all-solid-state battery is reduced, and defects such as penetration and short circuit of the solid electrolyte film due to lithium dendrite formation can be prevented. The elastic modulus of the solid electrolyte (PSE) may be, for example, 15 GPa to 35 GPa.

[0064] The solid electrolyte in the positive active material layer (120) may have a smaller average particle size compared to the solid electrolyte in the solid electrolyte layer (300) described later. For example, the average particle size of the solid electrolyte in the positive active material layer (120) may be 90% or less, 80% or less, 70% or less, 60% or less, 50% or less, 40% or less, 30% or less, or 20% or less of the average particle size of the solid electrolyte in the solid electrolyte layer (300). Meanwhile, the average particle size may be the median diameter measured using a laser particle size distribution meter.

[0065] The positive active material layer (120) may include a conductive material. The conductive material may have conductivity without causing chemical changes in the unit cell (CEL), thereby increasing the conductivity of the positive active material and the solid electrolyte. The conductive material may include a carbon-based material. The conductive material may include, for example, at least one of graphite, carbon black, acetylene black, carbon nanofiber, or carbon nanotube.

[0066] The positive active material layer (120) may further include a binder. The binder may bind the positive active material (PAM), solid electrolyte (PSE), and conductive material within the positive active material layer (120) together. The binder may include a material to improve the bonding strength between the positive active material layer (120) and the positive current collector (110). The binder may include, for example, at least one of polyvinylidene fluoride, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, or polymethyl methacrylate.

[0067] Based on 100 parts by weight of the total positive active material, solid electrolyte, conductive material, and binder, the positive active material layer (120) may contain 85 parts by weight or more and 92 parts by weight or less of the positive active material. Based on 100 parts by weight of the total positive active material, solid electrolyte, conductive material, and binder, the positive active material layer (120) may contain 0.5 parts by weight or more and 1.5 parts by weight or less of the binder.

[0068] Based on 100 parts by weight of solid electrolyte, the positive active material layer (120) may contain 1 part by weight or more and 50 parts by weight or less of a conductive material. If the conductive material is included in the positive active material layer (120) in an amount less than 1 part by weight based on 100 parts by weight of solid electrolyte, the proportion of the conductive material decreases, and the electrical conductivity of the positive active material layer (120) may decrease. If the conductive material is included in the positive active material layer (120) in an amount exceeding 50 parts by weight based on 100 parts by weight of solid electrolyte, the proportion of the conductive material is excessively high, and a coating layer covering the surface of the solid electrolyte may not be properly formed.

[0069] The positive active material layer (120) may further include additives such as fillers, coating agents, dispersants, and ion conductivity aids in addition to the positive active material, solid electrolyte, conductive material, and binder described above.

[0070] A solid electrolyte layer (300) may be provided between the anode layer (100) and the cathode layer (200). The solid electrolyte layer (300) may include a sulfide-based solid electrolyte with excellent lithium ion conductivity characteristics. The solid electrolyte in the solid electrolyte layer (300) may be the same as or different from any one of the materials included in the solid electrolyte in the aforementioned anode active material layer (120).

[0071] The solid electrolyte may have particle shapes such as spheres or ellipsoids. The solid electrolyte may include sulfide-based solid electrolytes. Sulfide-based solid electrolytes can be manufactured by processing starting materials, such as Li2S or P2S5, by methods such as melt quenching or mechanical milling. Additionally, heat treatment may be performed after such processing. The solid electrolyte may be amorphous, crystalline, or a mixture thereof. Furthermore, the solid electrolyte may include sulfur (S), phosphorus (P), and lithium (Li) as at least constituent elements among the sulfide-based solid electrolyte materials described above, for example. For example, the solid electrolyte may be a material containing Li2S-P2S5. When using a sulfide-based solid electrolyte material containing Li2S-P2S5 to form a solid electrolyte, the molar ratio of Li2S and P2S5 is, for example, in the range of Li2S : P2S5 = 50 : 50 to 90 : 10.

[0072] In one embodiment, the solid electrolyte is Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), or Li 7-x PS 6-x I x It may include an argyrodite-type compound comprising at least one of (0≤x≤2). The solid electrolyte may include an argyrodite-type compound comprising at least one of Li6PS5Cl, Li6PS5Br, or Li6PS5I.

[0073] In another embodiment, the solid electrolyte is Li 7-a M a PS 6-c X cIt may include an argyrodite-type compound comprising. Here, X may be Cl, Br, or a combination thereof. M may be Na, K, Fe, Mg, Ca, Ag, Cu, Zr, Zn, or a combination thereof. a and c may each be real numbers between 0 and 2.

[0074] The density of the azyrodite-type solid electrolyte may be 1.5 g / cc to 2.0 g / cc. Since the azyrodite-type solid electrolyte has a density of 1.5 g / cc or higher, the internal resistance of the all-solid-state battery is reduced, and defects such as penetration and short circuit of the solid electrolyte film due to lithium dendrite formation can be prevented. The elastic modulus of the solid electrolyte is, for example, 15 GPa to 35 GPa.

[0075] The solid electrolyte layer (300) may further include a binder. The binder included in the solid electrolyte layer (300) is, for example, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, etc., but is not limited to these. The binder of the solid electrolyte layer (300) may be the same as or different from the binder included in the positive active material layer (120) or the binder included in the coating layer (220).

[0076] The negative electrode layer (200) may include a negative electrode current collector (210) and a coating layer (220) on the negative electrode current collector (210).

[0077] The negative current collector (210) may provide a reference surface on which the coating layer (220) is disposed. The negative current collector (210) may include, for example, a material that does not react with lithium, that is, does not form any alloys or compounds with lithium. For example, the negative current collector (210) may include at least one of copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), aluminum (Al), silver (Ag), or an alloy thereof. The thickness of the negative current collector (210) may be 1 μm to 20 μm, more specifically 5 μm to 15 μm, more specifically 7 μm to 10 μm.

[0078] The negative current collector (210) may be composed of one of the metals described above, or may include an alloy of two or more metals or a coating material. The negative current collector (210) may, for example, have a plate-like or foil-like shape. Meanwhile, in one embodiment, the negative current collector (210) may be omitted.

[0079] The coating layer (220) can allow lithium metal to grow between the unit cell (CEL) and the negative current collector (210) during charging. The coating layer (220) can serve as a protective layer for the lithium metal and simultaneously suppress the precipitation and growth of lithium dendrites.

[0080] The coating layer (220) may include metal and carbon. For example, the coating layer (220) may include at least one metal selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). The coating layer (220) may include at least one carbon selected from the group consisting of carbon black, acetylene black, furnace black, ketjen black, and graphene. In one embodiment, the coating layer (220) may include a mixture (or composite) of carbon black and silver (Ag).

[0081] The coating layer (220) may have a smaller thickness compared to the positive active material layer (120). The thickness of the coating layer (220) may be, for example, 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, or 5% or less of the thickness of the positive active material layer (120). The thickness of the coating layer (220) may be, for example, 1 µm to 20 µm, 2 µm to 10 µm, or 3 µm to 7 µm. If the thickness of the coating layer (220) is excessively thin, lithium dendrites formed between the coating layer (220) and the negative current collector (210) may cause the coating layer (220) to collapse, thereby degrading the cycle characteristics of the unit cell (CEL). If the thickness of the coating layer (220) increases excessively, the energy density of the unit cell (CEL) decreases and the internal resistance of the unit cell (CEL) due to the coating layer (220) increases, which may degrade the cycle characteristics of the cell.

[0082] Meanwhile, although not shown, a carbon layer may be further included to improve adhesion between the coating layer (220) and the solid electrolyte layer (300).

[0083] In the embodiments described below, detailed descriptions of technical features that overlap with those previously described with reference to FIG. 1 are omitted, and differences are described in detail.

[0084] FIGS. 2 and FIGS. 3 are for illustrating an all-solid-state battery according to another embodiment of the present invention, FIG. 2 is a plan view of an all-solid-state battery according to another embodiment of the present invention, and FIG. 3 is a cross-sectional view along line AA' of FIG. 2.

[0085] Referring to FIGS. 2 and 3, the solid electrolyte layer (300) of the unit cell (CEL) according to the present invention may include a first solid electrolyte layer (310) and a second solid electrolyte layer (320). The first solid electrolyte layer (310) may be in contact with the anode layer (100), and the second solid electrolyte layer (320) may be in contact with the cathode layer (200).

[0086] The first and second solid electrolyte layers (310, 320) may each include a solid electrolyte and may further include a binder. The description of the solid electrolyte and binder is as described above.

[0087] The first solid electrolyte layer (310) may have a first thickness (TK1), and the second solid electrolyte layer (320) may have a second thickness (TK2). The first thickness (TK1) and the second thickness (TK2) may be the same or different from each other. In one embodiment, the first thickness (TK1) may be greater than the second thickness (TK2). For example, the first thickness (TK1) may be 1.1 to 5 times the second thickness (TK2). In another example, the first thickness (TK1) may be smaller than the second thickness (TK2).

[0088] The anode layer (100) and the first solid electrolyte layer (310) can form an anode composite layer (CSH). The cathode layer (200) and the second solid electrolyte layer (320) can form a cathode composite layer (ASH). An anode composite layer (CSH) can be laminated on the cathode composite layer (ASH).

[0089] The area of ​​the cathode composite layer (ASH) and the area of ​​the anode composite layer (CSH) may differ from each other. Specifically, the area of ​​the cathode composite layer (ASH) may be larger than the area of ​​the anode composite layer (CSH). The anode composite layer (CSH) may completely overlap within the cathode composite layer (ASH).

[0090] In one embodiment of the present invention, the first solid electrolyte layer (310) may have substantially the same area as the anode layer (100). The second solid electrolyte layer (320) may have substantially the same area as the cathode layer (200).

[0091] Specifically, the positive electrode composite layer (CSH) may have a first width (WI1) in a first direction (D1). The negative electrode composite layer (ASH) may have a second width (WI2) in a first direction (D1). The first width (WI1) may be smaller than the second width (WI2). The positive electrode composite layer (CSH) may have a third width (WI3) in a second direction (D2). The negative electrode composite layer (ASH) may have a fourth width (WI4) in a second direction (D2). The third width (WI3) may be smaller than the fourth width (WI4).

[0092] FIG. 4 is for illustrating an all-solid-state battery according to another embodiment of the present invention, FIG. 4 is a cross-sectional view along line AA' of FIG. 2. Referring to FIG. 4, the unit cell (CEL) according to the present invention may further include a gasket (GSK). The gasket (GSK) may be provided to surround the positive composite layer (CSH). The gasket (GSK) may fill the step difference on the side of the unit cell (CEL) caused by the difference in area between the negative composite layer (ASH) and the positive composite layer (CSH). The gasket (GSK) may surround the four sides of the positive composite layer (CSH). For example, the thickness of the gasket (GSK) may be substantially the same as the thickness of the positive composite layer (CSH). A substantially the same thickness may be defined as a difference in thickness of 10% or less.

[0093] FIG. 5 is for illustrating an all-solid-state battery according to another embodiment of the present invention, and FIG. 5 is a cross-sectional view along the line AA' of FIG. 2. Referring to FIG. 5, the negative electrode layer (200) of the unit cell (CEL) according to the present invention may further include a lithium metal layer (400) between the negative electrode current collector (210) and the coating layer (220). The lithium metal layer (400) may be formed during the charging of the unit cell (CEL), or its thickness may be further increased. The coating layer (220) serves as a protective layer for the lithium metal layer (400) and, at the same time, can suppress the growth of lithium dendrites from the lithium metal layer (400).

[0094] The lithium metal layer (400) may be a thin metal film containing lithium or a lithium alloy. The lithium alloy is not limited to, for example, Li-Al alloy, Li-Sn alloy, Li-In alloy, Li-Ag alloy, Li-Au alloy, Li-Zn alloy, Li-Ge alloy, Li-Si alloy, etc., and any alloy used as a lithium alloy is possible. The lithium metal layer (400) may contain one of these alloys or lithium. Alternatively, the lithium metal layer (400) may contain various types of alloys.

[0095] The lithium metal layer (400) may have a fifth width (WI5) in the first direction (D1). The fifth width (WI5) may be equal to or greater than the first width (WI1). The fifth width (WI5) may be equal to or smaller than the second width (WI2). For example, the fifth width (WI5) may be greater than the first width (WI1) and smaller than the second width (WI2).

[0096] FIG. 6 is a cross-sectional view illustrating an all-solid-state battery according to another embodiment of the present invention. Referring to FIG. 6, the unit cell (CEL) according to the present invention may be a bi-cell all-solid-state battery comprising a first monocell (MNC1) and a second monocell (MNC2). The first monocell (MNC1) and the second monocell (MNC2) may each include all the components of the aforementioned negative electrode layer (200), solid electrolyte layer (300), and positive electrode layer (100). The first monocell (MNC1) and the second monocell (MNC2) may be stacked so that the positive current collectors (110) are in contact with each other. The second monocell (MNC2) may be arranged vertically symmetrically with respect to the first monocell (MNC1).

[0097] FIG. 7 is a cross-sectional view illustrating an all-solid-state battery according to another embodiment of the present invention. Referring to FIG. 7, the unit cell (CEL) according to the present invention may be a bi-cell all-solid-state battery comprising a first monocell (MNC1) and a second monocell (MNC2), and may further include a gasket (GSK).

[0098]

[0099] All-solid-state battery system

[0100] FIG. 8 is a cross-sectional view illustrating an all-solid-state battery system according to one embodiment of the present invention.

[0101] Referring to FIG. 8, the all-solid-state battery system (SYS) according to the present invention may include a cell stack (LAM), end plates (ENP) sandwiching the cell stack, a polymer pad (PPD), and a fastening portion (FSN).

[0102] For example, a cell stack (LAM) may include a unit cell (CEL) and an elastic pad (EPD). The unit cell (CEL) and the elastic pad (EPD) may be in contact with each other. Unlike the illustration, in another example, the cell stack (LAM) in the present invention may include a unit cell (CEL) and omit the elastic pad (EPD). The description of the unit cell (CEL) is the same as described above.

[0103] The capacity of the cell stack (LAM) may be 2Ah to 120Ah. Unit cells (CEL) and elastic pads (EPD) may be stacked so that the capacity of the cell stack (LAM) satisfies the range described above.

[0104] An elastic pad (EPD) can relieve stress caused by volume changes in a unit cell (CEL) during charging and discharging. The elastic pad (EPD) may be composed of materials capable of elastic deformation. For example, the elastic pad (EPD) may include, but is not limited to, epoxy resin, acrylic resin, polyimide resin, polyester resin, polypropylene resin, polyamide resin, polystyrene resin, polyvinyl chloride resin, polycarbonate resin, fluoropolymer resin such as PTFE, silicone rubber, etc.

[0105] A unit cell (CEL) may include a plurality of unit cells. An elastic pad (EPD) may include a plurality of elastic pads. A plurality of unit cells and a plurality of elastic pads may be stacked alternately with each other. A unit cell (CEL) may be placed between two different elastic pads (EPD).

[0106] The end plates (ENP) can be configured to press the cell stack (LAM) in the thickness direction (third direction (D3)). The fastening portion (FSN) can be configured to restrain the end plates (ENP) from the thickness direction (third direction (D3)).

[0107] A conventional all-solid-state battery system (SYS) pressurizes a cell stack (LAM) using a washer spring and performs charging and discharging of the all-solid-state battery. A conventional all-solid-state battery system (SYS) may include a cell stack (LAM), end plates (ENP) sandwiching the cell stack, washer springs on the end plates, and a fastening portion (FSN). The washer spring may be applied near two or more vertices on the upper end plate and may be secured by the fastening portion (FSN). The washer spring can accommodate volume changes of the cell stack (LAM) and maintain the internal pressure of the cell stack (LAM) during charging and discharging. The washer spring may be made of metal. If the size of the cell stack (LAM) (e.g., area in the first direction (D1) and the second direction (D2)) increases, the thickness of the washer spring in the third direction (D3) for pressing the cell stack (LAM) may increase, or the number of washer springs may increase. In this case, the washer springs may occupy a significant amount of space within the all-solid-state battery system. Furthermore, since the washer springs are located near two or more vertices on the upper end plate, when the cell stack (LAM) is pressed by the washer springs, the pressure is concentrated near the washer springs, making it difficult to press the cell stack (LAM) uniformly.

[0108] A polymer pad (PPD) according to the present invention may be positioned between at least one of a cell laminate (LAM) and end plates (END). The polymer pad (PPD) may be in contact with one side of the cell laminate (LAM). The polymer pad (PPD) may be in contact with the cell laminate (LAM) and the end plates (END).

[0109] The polymer pad (PPD) can pressurize the cell stack (LAM). The polymer pad (PPD) can accommodate the volume expansion of the cell stack (LAM) during charging and discharging. The polymer pad (PPD) can apply uniform pressure as surface pressure to the entire surface of the cell stack (LAM) in contact with the polymer pad (PPD) during charging and discharging. The polymer pad (PPD) can pressurize the cell stack (LAM) uniformly. The polymer pad (PPD) can maintain the internal pressure of the cell stack (LAM) during charging and discharging. In other words, even when subjected to external forces caused by the expansion of the cell stack (LAM) during charging and discharging, the polymer pad (PPD) does not collapse or deform, and can uniformly pressurize the cell stack (LAM) as surface pressure. Thus, the polymer pad (PPD) can maintain the interfaces within the unit cell (CEL) so that they do not detach during charging and discharging, and can provide an all-solid-state battery system (SYS) with excellent charging and discharging efficiency and a long lifespan.

[0110] In addition, polymer pads (PPDs) can reduce or eliminate washer springs used in solid-state battery systems. Polymer pads (PPDs) can replace washer springs. Polymer pads (PPDs) can lighten the weight of the solid-state battery system (SYS). In addition, polymer pads (PPDs) can be configured to include more unit cells (CELs) within the solid-state battery system (SYS), allowing for more efficient use of space and increasing the capacity of the solid-state battery system (SYS).

[0111] The thickness (TKP) of the polymer pad (PPD) may be thinner than the thickness of the washer spring. The thickness (TKP) of the polymer pad (PPD) may be 1 mm to 1.5 cm. For example, the thickness (TKP) of the polymer pad (PPD) may be 2 mm to 1.2 cm.

[0112] For example, the ratio of the thickness (TKP) of the polymer pad (PPD) to the unit capacity of the cell stack (LAM) may be 1Ah : 0.05mm to 1Ah : 4mm, or 1Ah : 0.1mm to 1Ah : 2mm. For example, when the capacity of the cell stack (LAM) is 2Ah, the thickness (TKP) of the polymer pad (PPD) may be about 4mm. For example, when the capacity of the cell stack (LAM) is 20Ah, the thickness (TKP) of the polymer pad (PPD) may be about 8mm. For example, when the capacity of the cell stack (LAM) is 40Ah, the thickness (TKP) of the polymer pad (PPD) may be about 10mm. For example, if the capacity of the cell stack (LAM) is 120Ah, the thickness (TKP) of the polymer pad (PPD) can be about 12mm.

[0113] The density of the polymer pad (PPD) is 0.7 g / cm³ 3 Up to 1.5 g / cm² 3 It could be.

[0114] In one embodiment, the polymer pad (PPD) may include a plurality of polymer pads. For example, a plurality of polymer pads may be used to have a desired thickness (TKP). For example, the polymer pad (PPD) may include two polymer pads. One of the polymer pads may be located between the upper end plate of the cell stack (LAM) and the end plates (END). The other of the polymer pads may be located between the lower end plate of the cell stack (LAM) and the end plates (END). The two polymer pads may apply uniform pressure as surface pressure to both sides of the cell stack (LAM) during charging and discharging.

[0115] The polymer pad (PPD) will be described in more detail with reference to FIGS. 14 and FIGS. 15.

[0116] In the embodiments described below, detailed descriptions of technical features that overlap with those previously described with reference to FIGS. 1 to 8 are omitted, and differences are described in detail.

[0117] Referring to FIG. 9, the all-solid-state battery system (SYS) according to the present invention may further include a washer spring (SPW) having a relatively small thickness in the third direction (D3). The washer spring (SPW) may be applied near two or more vertices on the upper end plate among the end plates (ENP) and may be fixed by a fastening part (FSN). The all-solid-state battery system (SYS) according to the present invention can be made lighter by reducing the required thickness of the washer spring (SPW) compared to a conventional all-solid-state battery system. In addition, by reducing the thickness of the washer spring (SPW), the all-solid-state battery system (SYS) can be configured to include more unit cells (CEL), thereby utilizing space more efficiently and increasing the capacity of the all-solid-state battery system (SYS).

[0118] Referring to FIGS. 10 and 11, the all-solid-state battery system (SYS) according to the present invention may include only one polymer pad (PPD). Referring to FIGS. 12 and 13, the all-solid-state battery system (SYS) according to the present invention may include only one polymer pad (PPD) and may further include a washer spring (SPW) having a thickness in the third direction (D3) thinner than that of a typical all-solid-state battery system. The one polymer pad (PPD) may be located between the cell stack (LAM) and the upper end plate, or between the cell stack (LAM) and the lower end plate. When the capacity of the cell stack (LAM) is low, the all-solid-state battery system (SYS) according to the present invention can uniformly apply surface pressure to the entire surface of the cell stack (LAM) in contact with the polymer pad (PPD) even if it includes only one polymer pad (PPD), the all-solid-state battery system (SYS) can be made lighter, and the space within the all-solid-state battery system (SYS) can be utilized efficiently.

[0119]

[0120] Polymer pads (PPD) for all-solid-state batteries

[0121] FIGS. 14 and 15 are drawings for explaining a polymer pad for an all-solid-state battery according to embodiments of the present invention, and are enlarged views of the M region of FIG. 8.

[0122] Referring to FIG. 14, the polymer pad (PPD) may comprise a cross-linked polyurethane (CRP). The cross-linked polyurethane may be in a form in which different polyurethane chains are cross-linked (CRL). The cross-linking (CRL) may be formed in the hard segment (HSG) portion of the polyurethane chain. Unlike what is illustrated, the cross-linking (CRL) may comprise a form in which multiple cross-links are formed between two different polyurethanes, or a form in which multiple cross-links are formed between three or more different polyurethanes.

[0123] FIG. 15 shows that, in one embodiment of the present invention, the cross-linked polyurethane (CRP) may include allophanate. The cross-linked polyurethane (CRP) according to one embodiment may be prepared by reacting a thermoplastic polyurethane with a cross-linking agent comprising a plurality of isocyanate functional groups, as described below.

[0124] For example, in a spectrum measured using Fourier Transform Infrared Spectroscopy (FT-IR), the cross-linked polyurethane (CRP) within the polymer pad (PPD) may have absorption peaks for CN bonds, C=O bonds, and NH bonds. The absorption peaks for the CN bonds, C=O bonds, and NH bonds are each at 1100 cm⁻¹. -1 up to 1300cm -1 range of, 1600cm -1 up to 1800cm -1 range of, and 3100cm -1 up to 3500cm -1 It may appear within the range. Cross-linked polyurethane (CRP) may have a smaller size of the absorption peak for NH bonds than non-cross-linked polyurethane. Cross-linked polyurethane (CRP) may have larger sizes of the absorption peaks for CN bonds and C=O bonds than non-cross-linked polyurethane. The greater the degree of cross-linking within the cross-linked polyurethane (CRP), the smaller the absorption peak for NH bonds becomes, and the larger the sizes of the absorption peaks for CN bonds and C=O bonds become. For example, the ratio of the maximum intensity of the absorption peak for C=O bonds to the maximum intensity of the absorption peak for NH bonds (maximum intensity of C=O peak / maximum intensity of NH peak) was 0.68 to 0.75. For example, the ratio of the maximum intensity of the absorption peak for CN bonds to the maximum intensity of the absorption peak for NH bonds (maximum intensity of CN peak / maximum intensity of NH peak) was 0.45 to 0.6.

[0125] For example, in the results of analysis using Differential Scanning Calorimetry (DSC), the cross-linked polyurethane (CRP) within the polymer pad (PPD) has a relatively high melting point (T m It can have a higher melting point (T) than non-crosslinked polyurethane. m It can have a melting point (T) of 170°C or higher, or 177°C or higher. For example, cross-linked polyurethane (CRP) has a melting point (T) of 170°C or higher. m It can have ). In addition, for example, cross-linked polyurethane (CRP) has a melting point (T) of 190°C or lower, or 180°C or lower. m It may have ). For example, the heating rate may be 5℃ / min to 15℃ / min. The greater the degree of crosslinking in the crosslinked polyurethane (CRP), the higher the melting point (T m ) can become higher.

[0126] For example, when analyzing the amount of residue remaining after burning at 700°C using a thermogravimetric analyzer (TGA), the amount of residue remaining from the cross-linked polyurethane (CRP) in the polymer pad (PPD) may be greater than the amount of residue remaining from the non-cross-linked polyurethane. For example, the amount of residue remaining from the cross-linked polyurethane (CRP) may be 8% or more, or 11% or more, relative to the weight of the sample before burning. Additionally, for example, the amount of residue remaining from the cross-linked polyurethane (CRP) may be 15% or less relative to the weight of the sample before burning. For example, the heating rate may be 5°C / min to 15°C / min. The greater the degree of cross-linking in the cross-linked polyurethane (CRP), the greater the amount of residue remaining.

[0127] For example, when manufacturing a conventional all-solid-state battery system, a double press can be performed. Even if the polymer pad (PPD) is pressed twice, as in the manufacturing of an all-solid-state battery system, the degree of pressure loss may be relatively small.

[0128] For example, when a polymer pad (PPD) is pressed with a pressure of 2 MPa using a universal testing machine (UTM) at a temperature of 45°C and then rested for 3 hours, the degree of pressure loss of the polymer pad (PPD) may be 12% or less relative to 2 MPa, or 3% or more, or 6% or more.

[0129] For example, after the first press and rest, when the polymer pad (PPD) is pressed a second time at a pressure of 2 MPa and then rested for 3 hours, the degree of pressure loss of the polymer pad (PPD) may be 6% or less or 5% or less relative to 2 MPa, and may also be 1% or more or 2.2% or more.

[0130] When a double press is applied to the polymer pad (PPD), the degree of pressure loss may be less than when the polymer pad (PPD) contains non-crosslinked polyurethane. By including crosslinked polyurethane, the polymer pad (PPD) may have a strong characteristic of retaining external forces within the material. Even when subjected to external forces, the polymer pad (PPD) may hardly disperse those forces. The polymer pad (PPD) may not collapse or deform even when subjected to external forces. As a result, the polymer pad (PPD) can maintain the internal pressure of the unit cell (CEL) during charging and discharging.

[0131] Even if the polymer pad (PPD) undergoes repeated pressing and releasing processes, such as when charging and discharging an all-solid-state battery system, the degree of pressure loss may be relatively small. For example, when the process of pressing and releasing the polymer pad (PPD) is repeated 30 cycles using a universal testing machine (UTM) at a temperature of 45°C, the first cycle (1 st Pressure in the first cycle (1 cycle) relative to the first cycle (1 cycle) st cycle) and the 30th cycle (30 th The ratio of the pressure difference in cycles ((pressure of the first cycle - pressure of the 30th cycle) / pressure of the first cycle) can be relatively small.

[0132] For example, the difference between the maximum pressure of the first cycle and the 30th cycle, when compared to the maximum pressure of the first cycle ((maximum pressure of the first cycle - maximum pressure of the 30th cycle) / maximum pressure of the first cycle), may be 5% or less, 3% or less, or 0.5% or less.

[0133] For example, when comparing the difference between the lowest pressure of the first cycle and the 30th cycle with the lowest pressure of the first cycle ((lowest pressure of the first cycle - lowest pressure of the 30th cycle) / lowest pressure of the first cycle), it may be 40% or less, 30% or less, 20% or less, or 8% or less.

[0134] For example, the speed of the press and release may be 0.005 mm / s to 0.1 mm / s, and the distance may be 1 mm to 1.15 mm.

[0135] When the process of pressing and releasing the polymer pad (PPD) is repeated, the degree of pressure loss may be less than when the polymer pad (PPD) contains non-crosslinked polyurethane. By containing crosslinked polyurethane, the polymer pad (PPD) may have a strong characteristic of retaining external forces within the material. Even when subjected to external forces, the polymer pad (PPD) may hardly disperse those forces. The polymer pad (PPD) may not collapse or deform even when subjected to external forces. As a result, the polymer pad (PPD) can maintain the internal pressure of the unit cell (CEL) during charging and discharging.

[0136]

[0137] The polymer pad (PPD) and all-solid-state battery system (SYS) according to embodiments of the present invention may have the following effects.

[0138] The polymer pad (PPD) according to the present invention can pressurize a cell stack (LAM). The polymer pad (PPD) can accommodate volume expansion of the cell stack (LAM) during charging and discharging. The polymer pad (PPD) can apply uniform pressure as surface pressure to the entire surface of the cell stack (LAM) in contact with the polymer pad (PPD) during charging and discharging. The polymer pad (PPD) can pressurize the cell stack (LAM) uniformly. The polymer pad (PPD) can maintain internal pressure of the cell stack (LAM) during charging and discharging. The polymer pad (PPD) can reduce or eliminate washer springs used in an all-solid-state battery system (SYS). The polymer pad (PPD) can replace washer springs.

[0139] The all-solid-state battery system (SYS) according to the present invention can have excellent charge-discharge efficiency and a long lifespan. For example, when charging and discharging at a constant current of 0.33C at a temperature of 45°C, the charge-discharge efficiency of the cell stack (LAM) can be 97% or higher, and the capacity retention rate can be 88% or higher. The all-solid-state battery system (SYS) can be made lighter by reducing or omitting washer springs. In addition, by configuring the all-solid-state battery system (SYS) to include more unit cells (CEL), space can be utilized more efficiently, and the capacity of the all-solid-state battery system (SYS) can be increased.

[0140]

[0141] Method for manufacturing a polymer pad (PPD) for all-solid-state batteries

[0142] A polymer pad for an all-solid-state battery according to embodiments of the present invention can be manufactured by injection molding a thermoplastic polyurethane and a crosslinking agent by introducing them into an injection molding machine.

[0143] The thermoplastic polyurethane may include a hard segment (see HSG in FIG. 14). The hard segment may include isocyanate functional groups (-N=C=O) at both ends. The hard segment of the thermoplastic polyurethane may react with a crosslinking agent.

[0144] The crosslinking agent may include multiple isocyanate functional groups (-N=C=O). For example, the crosslinking agent may include two isocyanate functional groups. For example, the hard segment of a thermoplastic polyurethane may react with the isocyanate functional groups (-N=C=O) of the crosslinking agent, and an allophanate may be formed.

[0145] The thermoplastic polyurethane and the crosslinking agent may be mixed in a weight ratio of 950:50 to 850:150. For example, the thermoplastic polyurethane and the crosslinking agent may be mixed in a weight ratio of 950:50 to 870:130, or 930:70 to 870:130. If the weight ratio of the thermoplastic polyurethane and the crosslinking agent satisfies the ranges described above, a polymer pad comprising a crosslinked polyurethane having a desired degree of crosslinking can be manufactured.

[0146] The thermoplastic polyurethane and the crosslinking agent can react within an injection molding machine. For example, injection molding can be performed at a processing temperature of 205°C to 225°C. For example, injection molding can be performed at a mold temperature of 60°C to 80°C. For example, injection molding can be performed under a holding pressure condition of 90 bar to 110 bar. For example, injection molding can be performed at an injection speed of 90 rpm to 110 rpm. For example, injection molding can be performed at a screw speed of 140 rpm to 160 rpm. When injection molding is performed under the conditions described above, a polymer pad having a crosslinked polyurethane having a desired degree of crosslinking and a desired thickness can be manufactured.

[0147] The method for manufacturing a polymer pad for an all-solid-state battery according to the embodiments of the present invention can easily manufacture a polymer pad (PPD) having the characteristics described above. In addition, by using the method for manufacturing a polymer pad for an all-solid-state battery according to the present invention, the polymer pad (PPD) described above can be mass-produced.

[0148]

[0149] The present invention will be explained in more detail below through examples. However, these examples are intended to illustrate the invention and the scope of the invention is not limited to these examples.

[0150]

[0151] Example 1

[0152] (Manufacturing of polymer pads)

[0153] A polymer pad for an all-solid-state battery containing cross-linked polyurethane was manufactured by the following method. 950 g of thermoplastic polyurethane (BASF, 1185A10FHF) and 50 g of a crosslinking agent (BASF, X-Flex 2905) containing two isocyanate functional groups were fed into an injection molding machine to manufacture a polymer pad for an all-solid-state battery having a thickness of 2 mm and an area of ​​90 mm x 90 mm under a nitrogen atmosphere (crosslinking agent content = 5 wt%). The injection molding machine was set to a processing temperature of 215°C, a mold temperature of 70°C, a holding pressure of 100 bar, an injection speed of 100 rpm, and a screw speed of 150 rpm. The density of the polymer pad was 1.23 g / cm³. 3 was.

[0154] (Manufacturing of all-solid-state battery systems)

[0155] An all-solid-state battery system was manufactured comprising a cell stack, two end plates, two polymer pads, and a fastener. The two polymer pads were configured to sandwich the cell stack, and the cell stack and the two polymer pads were configured to sandwich between the two end plates.

[0156] The cell stack included a unit cell and an elastic pad, and the unit cell was a bi-cell all-solid-state battery. The bi-cell all-solid-state battery included two mono-cell all-solid-state batteries, and each mono-cell all-solid-state battery consisted of a negative electrode current collector (Ni-plated Cu (Ni-Cu), thickness = 10 µm), a coating layer (silver (Ag) particles (average particle size = 60 nm) and carbon black = 3:1 weight ratio), a solid electrolyte layer (Li6PS5Cl (average particle size = 3 µm, crystalline), thickness = 60 µm), and a positive electrode active material layer (positive electrode active material (LiNi 0.8 Co 0.15 Al 0.05The structure was stacked in the order of O2(NCA) : solid electrolyte (Li6PS5Cl, average particle size = 0.9㎛, crystalline) : conductive material : binder = 85 : 13.44 : 0.56 : 1 and positive current collector (aluminum foil, thickness = 10㎛). Within the bi-cell all-solid-state battery, two mono-cell all-solid-state batteries were symmetrically arranged so that their positive current collectors were in contact with each other. The cell stack was prepared to have a capacity of 2Ah (alternately stacking 8 unit cells and 9 elastic pads) or a capacity of 20Ah (alternately stacking 20 unit cells and 21 elastic pads). When the cell stack had a capacity of 2Ah, the all-solid-state battery system was manufactured using polymer pads with a thickness of 4mm. When the cell stack has a capacity of 20Ah, an all-solid-state battery system was manufactured using polymer pads to have a thickness of 8mm.

[0157]

[0158] Example 2

[0159] It was prepared in the same manner as Example 1, except that 900g of thermoplastic polyurethane (BASF, 1185A10FHF) and 100g of a crosslinking agent (BASF, X-Flex 2905) containing two isocyanate functional groups were added (content of crosslinking agent = 10 wt%).

[0160]

[0161] Comparative Example 1

[0162] A polymer pad for an all-solid-state battery was prepared in the same manner as in Example 1, except that 1000g of thermoplastic polyurethane (BASF, 1185A10FHF) and 0g of a crosslinking agent (BASF, X-Flex 2905) containing two isocyanate functional groups were added. That is, a polymer pad for an all-solid-state battery was prepared that did not contain any crosslinking agent (BASF, X-Flex 2905) containing two isocyanate functional groups.

[0163]

[0164] Comparative Example 2

[0165] An all-solid-state battery system containing no polymer pads was manufactured. The all-solid-state battery system included a cell stack, two end plates, a fastening part, and a washer spring part. The cell stack, the two end plates, and the fastening part are identical to those in Example 1. The washer spring part was located near the four vertices on the end plates and had a length of 2 cm in the third direction (D3).

[0166]

[0167] Experimental Example 1: Characterization of Polymer Pads (FT-IR Analysis)

[0168] FIGS. 16a, 16b, and 16c are the results of measurements taken using a Fourier Transform Infrared Spectroscopy (FT-IR) spectroscopy (NICOLET 4700, Thermo) on polymer pads for all-solid-state batteries according to Examples 1 and 2 and Comparative Example 1. A sample (1 cm x 1 cm x 2 mm) was prepared by cutting a polymer pad for an all-solid-state battery.

[0169] Referring to FIGS. 16a, 16b, and 16c, in the polymer pad for an all-solid-state battery according to Examples 1 and 2 and Comparative Example 1, 1100 cm -1 up to 1300cm -1 range of, 1600cm -1 up to 1800cm -1 range of, 3100cm -1 up to 3500cm -1Absorption peaks for CN bonds, C=O bonds, and NH bonds were observed, respectively, within the range. However, compared to the polymer pad for an all-solid-state battery according to Comparative Example 1, the absorption peak of the NH bond in the polymer pad for an all-solid-state battery according to Examples 1 and 2 gradually decreased, while the absorption peaks of the CN bond and the C=O bond gradually increased. Thus, it was confirmed that the polymer pad for an all-solid-state battery according to Examples 1 and 2 contains a cross-linked polyurethane formed by the reaction of a thermoplastic polyurethane and a crosslinking agent. That is, during the preparation of the polymer pad for an all-solid-state battery according to Examples 1 and 2, it was confirmed that as the isocyanate functional groups of the thermoplastic polyurethane and the crosslinking agent react to form allophanate, the CN bonds and C=O bonds increase, and the NH bonds decrease.

[0170] In addition, it was confirmed that the degree of crosslinking in the polymer pad for an all-solid-state battery according to Example 2 was greater compared to the crosslinked polyurethane in the polymer pad for an all-solid-state battery according to Example 1.

[0171] In the case of Example 1, the ratio of the maximum intensity of the absorption peak of the C=O bond to the maximum intensity of the absorption peak of the NH bond (maximum intensity of the C=O peak / maximum intensity of the NH peak) was 0.69. In addition, in the case of Example 1, the ratio of the maximum intensity of the absorption peak of the CN bond to the maximum intensity of the absorption peak of the NH bond (maximum intensity of the CN peak / maximum intensity of the NH peak) was 0.50.

[0172] In the case of Example 2, the ratio of the maximum intensity of the absorption peak of the C=O bond to the maximum intensity of the absorption peak of the NH bond (maximum intensity of the C=O peak / maximum intensity of the NH peak) was 0.70. In addition, in the case of Example 2, the ratio of the maximum intensity of the absorption peak of the CN bond to the maximum intensity of the absorption peak of the NH bond (maximum intensity of the CN peak / maximum intensity of the NH peak) was 0.55.

[0173] In the case of Comparative Example 1, the ratio of the maximum intensity of the absorption peak of the C=O bond to the maximum intensity of the absorption peak of the NH bond (maximum intensity of the C=O peak / maximum intensity of the NH peak) was 0.67. In addition, in the case of Comparative Example 1, the ratio of the maximum intensity of the absorption peak of the CN bond to the maximum intensity of the absorption peak of the NH bond (maximum intensity of the CN peak / maximum intensity of the NH peak) was 0.44.

[0174] Thus, it was confirmed that Examples 1 and 2, compared to Comparative Example 1, have a relatively large ratio of the maximum intensity of the absorption peak of the C=O bond to the maximum intensity of the absorption peak of the NH bond (maximum intensity of the C=O peak / maximum intensity of the NH peak) and the ratio of the maximum intensity of the absorption peak of the CN bond to the maximum intensity of the absorption peak of the NH bond (maximum intensity of the CN peak / maximum intensity of the NH peak).

[0175]

[0176] Experimental Example 2: Characterization of Polymer Pads (DSC Analysis)

[0177] Figure 17 shows the results of analyzing polymer pads for all-solid-state batteries according to Examples 1 and 2 and Comparative Example 1 using a Differential Scanning Calorimetry (DSC) (TA Instrument 2010 DSC). A 0.3g sample of a polymer pad for an all-solid-state battery, prepared by cutting, was placed in the Differential Scanning Calorimetry (DSC) and heated from room temperature to 200℃ at a rate of 10℃ / min.

[0178] Referring to FIG. 17, the polyurethane in the polymer pad for an all-solid-state battery according to Comparative Example 1 has a melting point (T m While ) is 166.3℃, the melting point (T) of the cross-linked polyurethane in the polymer pad for an all-solid-state battery according to Example 1 m) is 176.0℃, and the melting point (T) of the cross-linked polyurethane in the polymer pad for an all-solid-state battery according to Example 2 m The melting point was 178.3°C. The melting point of the cross-linked polyurethane in the polymer pad for an all-solid-state battery according to Example 1 was 9.7°C higher than the melting point of the polyurethane in the polymer pad for an all-solid-state battery according to Comparative Example 1. The melting point of the cross-linked polyurethane in the polymer pad for an all-solid-state battery according to Example 2 was 2.3°C higher than the melting point of the cross-linked polyurethane in the polymer pad for an all-solid-state battery according to Example 1. Thus, it was confirmed that the polymer pads for an all-solid-state battery according to Examples 1 and 2 contain cross-linked polyurethane. In addition, it was confirmed that the degree of cross-linking in the cross-linked polyurethane in the polymer pad for an all-solid-state battery according to Example 2 is higher compared to the cross-linked polyurethane in the polymer pad for an all-solid-state battery according to Example 1.

[0179]

[0180] Experimental Example 3: Characterization of Polymer Pads (TGA Analysis)

[0181] FIG. 18 shows the results of analyzing polymer pads for all-solid-state batteries according to Examples 1 and 2 and Comparative Example 1 using a thermogravimetric analyzer (TGA) (TGA2050. DSC2910. RCS, TA Instruments). A 0.5 g sample of a polymer pad for an all-solid-state battery, prepared by cutting, was placed in the thermogravimetric analyzer (TGA) and heated from room temperature to 700°C at a rate of 10°C / min under an oxygen gas atmosphere. The amount of residue remaining after burning at 700°C was the average value obtained by measuring five samples.

[0182] Referring to Fig. 18, the amount of residue remaining after burning at 700°C of the polyurethane in the polymer pad for an all-solid-state battery according to Comparative Example 1 was 5.7% relative to the weight of the sample.

[0183] The amount of residue remaining after burning at 700°C of the cross-linked polyurethane in the polymer pad for an all-solid-state battery according to Example 1 was 9.9% relative to the weight of the sample. Since 5% by weight of the cross-linking agent was added during the preparation of the polymer pad for an all-solid-state battery in Example 1, it was confirmed that almost all of the added cross-linking agent participated in the reaction to form cross-linked polyurethane.

[0184] The amount of residue remaining after burning at 700°C of the cross-linked polyurethane in the polymer pad for an all-solid-state battery according to Example 2 was 12.2% relative to the weight of the sample. Since 10% by weight of the cross-linking agent was added during the manufacture of the polymer pad for an all-solid-state battery in Example 2, it was confirmed that all of the added cross-linking agent participated in the reaction to form cross-linked polyurethane. Considering the fact that some loss occurs during injection molding, it was also confirmed that the cross-linking agent should be added at a maximum of 10% by weight.

[0185]

[0186] Experimental Example 4: Evaluation of pressure retention rate of polymer pad (1)

[0187] The degree of pressure release when force is applied to the polymer pads for all-solid-state batteries according to Examples 1 and 2 and Comparative Example 1 was evaluated through a compression test. A laminate of five stacked polymer pads was used as the sample for the compression test, and the test was performed using a Universal Test Machine (UTM) (Shimadzu) at a temperature of 45°C. The compression test was performed by measuring the external force or pressure applied when the polymer pad is contracted. The pressure retention rate was evaluated in two ways as follows.

[0188] In the first method, the pressure retention rate was evaluated by calculating the degree of pressure loss when the system was pressed twice, as is typically done when manufacturing all-solid-state battery systems. The first stress was measured by applying a first press of 2 MPa to a laminate (thickness = 1 mm) of five polymer pads using a universal testing machine, leaving it for 3 hours, and then measuring the pressure. The second stress was measured by applying a second press of 2 MPa to the laminate after the first press and leaving it for 3 hours, and then leaving it for 3 hours. The degree of pressure loss was expressed as the ratio of the difference between the applied pressure (2 MPa) and the measured stress to the applied pressure (2 MPa). The results are shown in Table 1.

[0189] In the second method, a laminate of five polymer pads was first pressed to 2 MPa at a speed of 0.01 mm / s. Subsequently, the process of pressing to 1 mm at a speed of 0.01 mm / s and releasing to 1 mm at a speed of 0.01 mm / s was repeated for 30 cycles. The degree of pressure release was expressed as a ratio of the difference between the maximum pressure of one cycle and the maximum pressure of 30 cycles relative to the maximum pressure of one cycle. Additionally, the degree of pressure release was expressed as a ratio of the difference between the minimum pressure of one cycle and the minimum pressure of 30 cycles relative to the minimum pressure of one cycle. The results are shown in Figures 19a and 19b and Table 2.

[0190]

[0191] Classification Primary Stress (MPa) Degree of Pressure Reduction ((2MPa - Primary Stress) / 2MPa) (%) Secondary Stress (MPa) Degree of Pressure Reduction ((2MPa - Secondary Stress) / 2MPa) (%) Example 1 1.8 9 5.5 0 1.9 6 2.00 Example 2 1.7 9 10.5 1.9 5 2.50 Comparative Example 1 1.6 6 17.0 1.8 3 8.50

[0192]

[0193] Classification 1st Cycle 30th Cycle Degree of pressure drop ((Pressure of 1st Cycle - Pressure of 30th Cycle) / Pressure of 1st Cycle) (%) Maximum pressure (MPa) Minimum pressure (MPa) Maximum pressure (MPa) Minimum pressure (MPa) (Maximum pressure of 1st Cycle - Maximum pressure of 30th Cycle) / Maximum pressure of 1st Cycle (Minimum pressure of 1st Cycle - Minimum pressure of 30th Cycle) / Minimum pressure of 1st Cycle Example 15.5 10.3 75.3 00.2 53.8 03 2.4 Example 25.5 50.4 05.5 50.3 00.0 25.0 Comparative Example 15.7 00.6 45.6 50.2 90.8 85 4.7

[0194]

[0195] Referring to FIG. 19b, a graph with a narrower width was obtained for the polymer pads for all-solid-state batteries according to Examples 1 and 2 than for the polymer pad for all-solid-state batteries according to Comparative Example 1. Referring to Tables 1 and 2, the polymer pads for all-solid-state batteries according to Examples 1 and 2 showed a relatively smaller degree of pressure release. In other words, it was confirmed that the polymer pads for all-solid-state batteries according to Examples 1 and 2, by including cross-linked polyurethane, possess a characteristic of retaining externally applied force within the cross-linked polyurethane material. On the other hand, it was confirmed that the polymer pad for all-solid-state batteries according to Comparative Example 1 exhibited a characteristic of rapidly dispersing the force when subjected to external force.

[0196] Thus, the polymer pad for an all-solid-state battery according to Examples 1 and 2 can pressurize the cell stack, accommodate volume expansion of the cell stack during charging and discharging, and maintain the internal pressure of the unit cell well during charging and discharging.

[0197]

[0198] Experimental Example 5: Evaluation of pressure retention rate of polymer pad (2)

[0199] Through a compression test, the degree of pressure loss when force is applied to a polymer pad for a solid-state battery using the solid-state battery systems according to Examples 1 and 2 and Comparative Example 1 was evaluated.

[0200] As a sample for the compression test, an all-solid-state battery system comprising a cell stack, two end plates, two polymer pads, and a fastener was used. The two polymer pads were configured to sandwich the cell stack, and the cell stack and the two polymer pads were configured to sandwich between the two end plates. As the cell stack, 26 aluminum plates and 27 elastic pads were alternately stacked to have the same density and thickness as a cell stack with a capacity of 20 Ah.

[0201] Compression tests were performed using a Universal Test Machine (UTM) (Shimadzu) at a temperature of 45°C. The compression test was conducted by measuring the external force or pressure applied when the polymer pad was contracted. Pressure retention rates were evaluated in two ways as follows.

[0202] In the first method, the pressure retention rate was evaluated by calculating the degree of pressure loss when pressed twice, as is typically done when manufacturing all-solid-state battery systems. The first stress was measured by applying a first press of 2 MPa to the polymer pad using a universal testing machine, leaving it for 3 hours, and then measuring the pressure. The second stress was measured by applying a second press of 2 MPa to the polymer pad after the first press and leaving it for 3 hours, and then measuring the pressure. The degree of pressure loss was expressed as the ratio of the difference between the applied pressure (2 MPa) and the measured stress to the applied pressure (2 MPa). The results are shown in Table 3.

[0203] In the second method, considering that the internal pressure of the all-solid-state battery at full charge (SOC100) is 2MPa to 4MPa and at discharge (SOC0) is 1MPa to 1.5MPa, and that there is a thickness change of approximately 1mm during charging and discharging of the all-solid-state battery, the pressure retention rate was evaluated when pressing and releasing up to a maximum of 1.15mm. First, the polymer pad was pressed to 2MPa at a speed of 0.01mm / s. Subsequently, the process of pressing to 1.15mm at a speed of 0.01mm / s and releasing to 1.15mm at a speed of 0.01mm / s was repeated for 30 cycles. The degree of pressure loss was expressed as the ratio of the difference between the maximum pressure of one cycle and the maximum pressure of 30 cycles relative to the maximum pressure of one cycle. In addition, the degree of pressure drop was expressed as a ratio of the difference between the lowest pressure of one cycle and the lowest pressure of 30 cycles relative to the lowest pressure of one cycle. The results are shown in Fig. 20 and Table 4.

[0204]

[0205] Classification Primary Stress (MPa) Degree of Pressure Loss ((2MPa - Primary Stress) / 2MPa) (%) Secondary Stress (MPa) Degree of Pressure Loss ((2MPa - Secondary Stress) / 2MPa) (%) Example 1 1.73 10.5 1.89 5.50 Example 2 1.80 10.0 1.94 1.50 Comparative Example 1 1.59 20.5 1.79 10.5

[0206]

[0207] Classification 1st Cycle 30th Cycle Degree of pressure drop ((Pressure of 1st Cycle - Pressure of 30th Cycle) / Pressure of 1st Cycle) (%) Maximum pressure (MPa) Minimum pressure (MPa) Maximum pressure (MPa) Minimum pressure (MPa) (Maximum pressure of 1st Cycle - Maximum pressure of 30th Cycle) / Maximum pressure of 1st Cycle (Minimum pressure of 1st Cycle - Minimum pressure of 30th Cycle) / Minimum pressure of 1st Cycle Example 13.42 1.44 3.26 1.30 4.68 9.72 Example 23.25 1.50 3.29 1.40 1.23 6.67 Comparative Example 13.15 1.30 2.76 1.03 12.42 0.8

[0208]

[0209] Referring to Tables 3 and 4 and FIG. 20, the all-solid-state battery system according to Examples 1 and 2 showed less pressure loss than the all-solid-state battery system according to Comparative Example 1. That is, it was confirmed that in the all-solid-state battery system according to Examples 1 and 2, the polymer pad containing cross-linked polyurethane effectively transfers external force between the chains within the cross-linked polyurethane material, thereby improving the pressure-maintaining properties. On the other hand, in the all-solid-state battery system according to Comparative Example 1, it was confirmed that when the polymer pad receives external force, that force is rapidly dissipated.

[0210] Thus, it was confirmed that the polymer pad for all-solid-state batteries can pressurize the cell stack, accommodate the volume expansion of the cell stack during charging and discharging, maintain the internal pressure of the unit cell well during charging and discharging, and replace or reduce washer springs when manufacturing an all-solid-state battery system.

[0211]

[0212] Experimental Example 6: Computer Simulation Analysis

[0213] FIGS. 21 to 23 show the results of analyzing the pressure deviation within a cell stack using computer simulation (Ansys Mechanical) when the cell stack is pressed with a polymer pad and / or washer spring in an all-solid-state battery system according to Example 1 and Comparative Example 2. Pressure deviation refers to the difference between the average pressure and the pressure measured at a specific point within the cell stack. Distribution refers to the ratio of the area of ​​a region having a specific pressure deviation to the total cross-sectional area of ​​the cell stack. FIG. 21 shows the results for an all-solid-state battery system according to Example 1, FIG. 22 shows the results for an all-solid-state battery system with a washer spring (SPW) added to Example 1, and FIG. 23 shows the results for an all-solid-state battery system according to Comparative Example 2. The polymer pad (PPD) was set to have a thickness of 3 mm.

[0214] Referring to FIGS. 21 and 23, the all-solid-state battery system according to Comparative Example 2 had uneven pressure within the cell stack due to the washer spring (SPW), and the pressure variation in the thickness direction of the cell stack was large. On the other hand, the all-solid-state battery system according to Example 1 had relatively uniform pressure within the cell stack and a small pressure variation in the thickness direction of the cell stack. Referring to FIG. 22, the all-solid-state battery system with the addition of a washer spring (SPW) to Example 1 had more uniform pressure within the cell stack and a smaller pressure variation in the thickness direction of the cell stack than Comparative Example 1.

[0215] Thus, it was confirmed that when a polymer pad (PPD) is applied to an all-solid-state battery system, a uniform pressure can be applied to the cell stack as a surface pressure compared to when a washer spring (SPW) is applied, and the problem of pressure non-uniformity within the cell stack can be improved.

[0216]

[0217] Experimental Example 7: Performance Evaluation of All-Solid State Battery

[0218] FIGS. 24 to 26 are the results of evaluating the discharge capacity, charge / discharge efficiency, and lifespan of an all-solid-state battery using an all-solid-state battery system according to Example 2 and Comparative Example 2.

[0219] As a sample for performance evaluation, an all-solid-state battery system comprising a cell stack, two end plates, two polymer pads, and a fastener was used. The two polymer pads were configured to sandwich the cell stack, and the cell stack and the two polymer pads were configured to sandwich between the two end plates. A cell stack with a capacity of 2Ah was used.

[0220] The performance of the all-solid-state battery was tested by placing it in a constant temperature bath at 45°C. In the first cycle, the battery was charged with a constant current of 0.33C until the battery voltage reached 4.25V, and upon reaching 4.25V, constant voltage charging was performed at 4.25V with a cut-off condition of 0.05C. Subsequently, the battery was discharged with a constant current of 0.33C until the battery voltage reached 2.5V. The ratio of the discharge capacity to the charge capacity in the first cycle was defined as the charge-discharge efficiency. The above cycles were repeated, and the lifespan was evaluated based on the capacity retention rate (the ratio of the discharge capacity in the nth cycle to the initial discharge capacity).

[0221] Referring to FIGS. 24 and 25, the all-solid-state battery system according to Example 2 had superior charge-discharge efficiency compared to the all-solid-state battery system according to Comparative Example 2. Referring to FIG. 26, the all-solid-state battery system according to Example 2 had an improved capacity retention rate compared to the all-solid-state battery system according to Comparative Example 2. That is, under the same charge-discharge conditions, unlike the all-solid-state system according to Comparative Example 2, the all-solid-state battery system according to Example 2 maintains a uniform internal pressure during charge-discharge, and because a uniform pressure is applied to the cell stack as surface pressure due to the polymer pad, it was confirmed that it has superior charge-discharge efficiency and lifespan characteristics.

[0222]

[0223] Experimental Example 8: Analysis of the negative electrode layer after performance evaluation of the all-solid-state battery

[0224] FIGS. 27 and 28 are images of a negative electrode layer obtained by disassembling a cell stack immediately after evaluating the lifespan of an all-solid-state battery system according to Example 2 and Comparative Example 2.

[0225] Referring to FIGS. 27 and 28, it was confirmed that in the all-solid-state battery system according to Comparative Example 2, significant pressure was applied to the edge portion of the negative electrode layer after charging and discharging. On the other hand, in the all-solid-state battery system according to Example 2, it was confirmed that no pressure was applied to the edge portion of the negative electrode layer after charging and discharging, thus confirming that uniform pressure was applied to the cell stack as surface pressure. Thus, it was confirmed that using a polymer pad can improve the problem of pressure non-uniformity within the cell stack during charging and discharging.

[0226]

[0227] Although embodiments of the present invention have been described above with reference to the attached drawings, the present invention may be implemented in other specific forms without altering its technical concept or essential features. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive.

Claims

1. Melting point (T) during Differential Scanning Calorimetry (DSC) analysis m ) includes cross-linked polyurethane at a temperature of 170°C or higher, and With a thickness of 1 mm to 1.5 cm, Polymer pad for all-solid-state batteries.

2. In Paragraph 1, The above-mentioned cross-linked polyurethane comprises allophanate, Polymer pad for all-solid-state batteries.

3. In Paragraph 1, The density of the above polymer pad is 0.7 g / cm³ 3 Up to 1.5 g / cm² 3 person, Polymer pad for all-solid-state batteries.

4. In Paragraph 1, When the process of pressing the polymer pad with a pressure of 2 MPa using a universal testing machine (UTM) at a temperature of 45°C and then resting it for 3 hours is repeated twice, the degree of pressure loss of the polymer pad is 6% or less, Polymer pad for all-solid-state batteries.

5. In Paragraph 1, When the process of pressing and releasing the polymer pad to 1 mm at a speed of 0.01 mm / s using a universal testing machine (UTM) at a temperature of 45℃ is repeated for 30 cycles, the degree of pressure release of the polymer pad in the 30th cycle compared to the first cycle is 40% or less, Polymer pad for all-solid-state batteries.

6. A cell laminate comprising a unit cell and an elastic pad; End plates sandwiching the above cell stack; A polymer pad located between the cell stack and at least one of the end plates; and Includes a connecting part, The above polymer pad is the polymer pad described in claim 1, All-solid-state battery system.

7. In Paragraph 6, The cross-linked polyurethane of the polymer pad comprises allophanate. All-solid-state battery system.

8. In Paragraph 6, The density of the above polymer pad is 0.7 g / cm³ 3 Up to 1.5 g / cm² 3 person, All-solid-state battery system.

9. In Paragraph 6, When the process of pressing the polymer pad with a pressure of 2 MPa using a universal testing machine (UTM) at a temperature of 45°C and then resting it for 3 hours is repeated twice, the degree of pressure loss of the polymer pad is 6% or less, All-solid-state battery system.

10. In Paragraph 6, When the process of pressing and releasing the polymer pad up to 1 mm at a speed of 0.01 mm / s using a universal testing machine (UTM) at a temperature of 45℃ is repeated for 30 cycles, the degree of pressure release of the polymer pad in the 30th cycle compared to the first cycle is 40% or less, All-solid-state battery system.

11. In Paragraph 6, The polymer pad is configured to provide surface pressure to the cell stack. All-solid-state battery system.

12. In Paragraph 6, The above polymer pad includes a plurality of polymer pads, and The plurality of polymer pads are each located between the cell stack and the end plates, All-solid-state battery system.

13. In Paragraph 6, The above-described all-solid-state battery system is configured to omit or reduce washer springs, All-solid-state battery system.

14. In Paragraph 6, When charging and discharging are repeated for 60 cycles with a constant current of 0.33C at a temperature of 45℃, the charge-discharge efficiency of the cell stack is 97% or higher, All-solid-state battery system.

15. In Paragraph 6, When charging and discharging are repeated for 60 cycles with a constant current of 0.33C at a temperature of 45℃, the capacity retention rate of the cell stack is 88% or higher, All-solid-state battery system.

16. Including injection molding by introducing thermoplastic polyurethane and a crosslinking agent into an injection molding machine, wherein The above crosslinking agent comprises a plurality of isocyanate functional groups, Method for manufacturing a polymer pad for an all-solid-state battery.

17. In Paragraph 16, The weight ratio of the thermoplastic polyurethane and the crosslinking agent is 950:50 to 850:150, Method for manufacturing a polymer pad for an all-solid-state battery.

18. In Paragraph 16, The above injection molding is performed under conditions of a processing temperature of 205°C to 225°C, a mold temperature of 60°C to 80°C, a holding pressure of 90 bar to 110 bar, an injection speed of 90 rpm to 110 rpm, and a screw speed of 140 rpm to 160 rpm. Method for manufacturing a polymer pad for an all-solid-state battery.

19. In Paragraph 16, The above injection molding includes forming an allophanate. Method for manufacturing a polymer pad for an all-solid-state battery.

20. In Paragraph 16, The above injection molding comprises forming a polymer pad having a thickness of 1 mm to 1.5 cm. Method for manufacturing a polymer pad for an all-solid-state battery.

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