Solid electrolyte-positive electrode assembly and manufacturing method thereof, secondary battery and manufacturing method thereof, and electrolyte layer of secondary battery

Abstract

The present invention relates to a solid electrolyte-cathode assembly and a manufacturing method thereof, a secondary battery and a manufacturing method thereof, and an electrolyte layer of a secondary battery. The solid electrolyte-cathode assembly includes a plurality of cathode layers spaced apart from each other in a first direction, and an electrolyte layer including an amorphous solid electrolyte and a crystalline solid electrolyte including a plurality of crystalline solid electrolyte particles, wherein the amorphous solid electrolyte is on a surface of a cathode layer of the plurality of cathode layers and the crystalline solid electrolyte is within the amorphous solid electrolyte.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to and the benefit of Korean Patent Application No. 10-2019-0134794, filed on October 28, 2019, in the Korean Intellectual Property Office, the contents of which are incorporated herein by reference in their entirety. Technical Field

[0003] The present disclosure relates to secondary batteries and methods of manufacturing the same. Background Art

[0004] Unlike primary batteries, secondary batteries are rechargeable and can be used in a variety of electronic devices such as cellular phones, laptops, and camcorders. In particular, lithium secondary batteries can be characterized by higher voltage and higher energy density compared to nickel-cadmium batteries and nickel-metal hydride batteries. Therefore, the demand for lithium secondary batteries is increasing.

[0005] As the types of electronic devices that include secondary batteries have become more diverse and the related market has grown, the demand for secondary batteries with improved performance in multiple aspects, such as increased energy density, improved rate performance, increased stability and durability, and improved flexibility, has increased. Energy density is related to an increase in the capacity of a secondary battery, and rate performance is related to an improvement in the charging speed of a secondary battery. Therefore, there is still a need for improved battery materials. Summary of the Invention

[0006] A solid electrolyte-cathode assembly for a secondary battery is provided that includes a three-dimensional ("3D") electrode structure and provides improved capacity and enhanced rate capability.

[0007] Methods of making solid electrolyte-positive electrode assemblies for secondary batteries that include three-dimensional ("3D") electrode structures and provide improved capacity and enhanced rate capability are provided.

[0008] Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description.

[0009] According to an embodiment, a solid electrolyte-positive electrode assembly for a secondary battery includes: a plurality of positive electrode layers spaced apart from each other in a first direction, and an electrolyte layer, the electrolyte layer including an amorphous solid electrolyte and a crystalline solid electrolyte including a plurality of crystalline solid electrolyte particles, wherein the amorphous solid electrolyte is on the surface of the positive electrode layers of the plurality of positive electrode layers, and the crystalline solid electrolyte is within (inside) the amorphous solid electrolyte.

[0010] The crystalline solid electrolyte may be present in the electrolyte layer in an amount of about 10 volume percent (vol %) to about 99 vol % based on the total volume of the electrolyte layer.

[0011] The electrolyte layer may have a thickness measured in the first direction of about 100 nanometers (nm) to about 100 micrometers (μm).

[0012] The plurality of crystalline solid electrolyte particles may have an average particle size of about 100 nm to about 100 μm.

[0013] A ratio of an average particle size of the plurality of crystalline solid electrolyte particles to a thickness of the electrolyte layer measured in the first direction may be about 0.15:1 to about 0.25:1.

[0014] The solid electrolyte-positive electrode assembly may further include a positive electrode current collector facing the respective ends (ends) of the multiple positive electrode layers and contacting a portion of each of the multiple positive electrode layers, wherein the surfaces of the positive electrode layers of the multiple positive electrode layers on which the amorphous solid electrolyte is present may be different from the respective ends of the multiple positive electrode layers facing the positive electrode current collector.

[0015] Each of the plurality of positive electrode layers may include a first surface and a second surface opposite to each other, and a third surface and a fourth surface each extending between the first surface and the second surface, wherein the third surface and the fourth surface each may have a surface area smaller than the surface area of ​​each of the first surface and the second surface, wherein the third surface and the fourth surface may be opposite to each other. The first surface of the first positive electrode layer and the second surface of the second positive electrode layer adjacent to the first positive electrode layer may face each other.

[0016] The electrolyte layer may be on the first surface and the second surface of each of the plurality of positive electrode layers.

[0017] The ratio of the thickness of the first portion of the electrolyte layer measured in the first direction to the thickness of the second portion of the electrolyte layer measured in the first direction may be about 0.1:1 to about 1:1, the solid electrolyte-positive electrode assembly may further include a positive electrode collector on which the multiple positive electrode layers are arranged, and the first portion of the electrolyte layer may be farther away from the positive electrode collector than the second portion of the electrolyte layer in a second direction perpendicular to the first direction.

[0018] The crystalline solid electrolyte may include first and second crystalline solid electrolyte particles having different average particle sizes, and a ratio of the average particle size of the first crystalline solid electrolyte particles to the average particle size of the second crystalline solid electrolyte particles may be about 0.05 to about 0.5.

[0019] The ionic conductivity of the electrolyte layer may be about 10 -6 Siemens / cm (S / cm) - about 10 -4 S / cm.

[0020] The electrolyte layer may be a product of heat treatment at a temperature of about 50°C to about 700°C.

[0021] The crystalline solid electrolyte may include Li 3+x La3M2O 12 , wherein M is at least one of Te, Nb or Zr, and 0≤x≤10.

[0022] The amorphous solid electrolyte may include Li 3+x La3M2O 12 , wherein M is at least one of Te, Nb or Zr, and 0≤x≤10.

[0023] According to an embodiment, a secondary battery includes: a negative electrode layer on the solid electrolyte-positive electrode assembly; and a negative electrode current collector contacting a portion of the negative electrode layer and facing the positive electrode current collector, wherein the negative electrode layer is on the first surface and the second surface of each of the plurality of positive electrode layers.

[0024] According to an embodiment, a solid electrolyte-positive electrode assembly for a secondary battery includes a plurality of positive electrode layers spaced apart from each other in a first direction, and an electrolyte layer on the surface of the positive electrode layers of the plurality of positive electrode layers. The electrolyte layer includes: a first amorphous solid electrolyte layer on the positive electrode layers of the plurality of positive electrode layers; a mixed solid electrolyte layer on the first amorphous solid electrolyte layer, the mixed solid electrolyte layer including a plurality of third crystalline solid electrolyte particles in a second amorphous solid electrolyte; and a third amorphous solid electrolyte layer on the mixed solid electrolyte layer.

[0025] A ratio of an average particle size of the plurality of third crystalline solid electrolyte particles to a thickness of a sum of the first amorphous solid electrolyte layer and the third amorphous solid electrolyte layer measured in the first direction may be about 0.5:1 to about 1:1.

[0026] A plurality of fourth crystalline solid electrolyte particles may be in at least one of the first amorphous solid electrolyte layer, the mixed solid electrolyte layer, or the third amorphous solid electrolyte layer.

[0027] A ratio of an average particle size of the plurality of fourth crystalline solid electrolyte particles to an average particle size of the plurality of third crystalline solid electrolyte particles may be from about 0.05:1 to about 0.3:1.

[0028] According to an embodiment, a secondary battery includes a negative electrode layer on the solid electrolyte-positive electrode assembly.

[0029] According to an embodiment, a method for manufacturing a solid electrolyte-positive electrode assembly for a secondary battery includes: arranging a plurality of positive electrode layers spaced apart from each other in a first direction on a positive electrode current collector, coating a first amorphous solid electrolyte on the positive electrode layer of the plurality of positive electrode layers to provide a first amorphous solid electrolyte-coated positive electrode layer, heat treating the first amorphous solid electrolyte-coated positive electrode layer to provide a heat-treated first amorphous solid electrolyte-coated positive electrode layer, coating a mixture of a second amorphous solid electrolyte and a crystalline solid electrolyte including a plurality of crystalline solid electrolyte particles on the heat-treated first amorphous solid electrolyte-coated positive electrode layer to provide a coated mixture, heat treating the coated mixture to provide a heat-treated mixture, coating a third amorphous solid electrolyte on the heat-treated mixture to provide an amorphous solid electrolyte material, and heat treating the amorphous solid electrolyte material to manufacture the solid electrolyte-positive electrode assembly.

[0030] Heat-treating the first amorphous solid electrolyte-coated positive electrode layer, heat-treating the coated mixture, or heat-treating the amorphous solid electrolyte material may each independently include heat-treating at about 50° C. to about 700° C.

[0031] Coating the first amorphous solid electrolyte, the mixture of the second amorphous solid electrolyte and the crystalline solid electrolyte, or the third amorphous solid electrolyte may each independently include spin coating or dip coating.

[0032] According to an embodiment, a method of manufacturing a secondary battery includes: providing a negative electrode layer; providing the solid electrolyte-positive electrode assembly; and disposing the negative electrode layer on the solid electrolyte-positive electrode assembly to manufacture the secondary battery.

[0033] According to an embodiment, the electrolyte layer of a secondary battery includes: an amorphous solid electrolyte; and a plurality of crystalline solid electrolyte particles, wherein the electrolyte layer has a thickness of about 100 nanometers to about 100 micrometers, wherein the average particle size of the plurality of crystalline solid electrolyte particles is about 100 nanometers to about 100 micrometers, and wherein the ratio of the average particle size of the plurality of crystalline solid electrolyte particles to the thickness of the electrolyte layer is about 0.15:1 to about 0.25:1. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The above and other aspects, features and advantages of some embodiments of the present disclosure will become more apparent from the following description considered in conjunction with the accompanying drawings, in which:

[0035] Figure 1A is a perspective view of an embodiment of a secondary battery;

[0036] Figure 1B is a cross-sectional view of an embodiment of a secondary battery;

[0037] Figure 1C for Figure 1B The enlarged part;

[0038] Figure 1D is a perspective view of an embodiment of a positive electrode layer, an electrolyte layer, and a first current collecting layer included in a secondary battery;

[0039] Figure 2A is a scanning electron microscope ("SEM") image of an embodiment of an electrolyte layer;

[0040] Figure 2B SEM images of embodiments of the electrolyte layer and the positive electrode layer;

[0041] Figure 3A is a cross-sectional view of a secondary battery according to Comparative Example 1;

[0042] Figure 3B for Figure 3A The enlarged part;

[0043] Figure 3C is an SEM image of the electrolyte layer according to Comparative Example 1;

[0044] Figure 4A is a cross-sectional view of a secondary battery according to Comparative Example 2;

[0045] Figure 4B for Figure 4A The enlarged part;

[0046] Figure 4C is an SEM image of the electrolyte layer according to Comparative Example 2;

[0047] Figure 5 is a graph of ionic conductivity (S / cm) versus process temperature (°C), which shows the relationship between the heat treatment process temperature of the electrolyte layer and its ionic conductivity;

[0048] Figure 6 is the Nyquist plot of the imaginary impedance Z" (ohm centimeters (Ω·cm)) versus the real impedance Z' (Ω·cm), which shows that the comparative example 1 (crystallized Li7La3Zr2O 12 ("LLZO") (powder)), Comparative Example 2 (amorphous LLZO (thin film)), and hybrid LLZO embodiments;

[0049] Figure 7 is a cross-sectional view of an embodiment of a positive electrode layer, an electrolyte layer, and a first current collecting layer;

[0050] Figure 8is a cross-sectional view of an embodiment of a positive electrode layer and an electrolyte layer;

[0051] Figure 9A is a cross-sectional view of an embodiment of a positive electrode layer, an electrolyte layer, and a negative electrode layer;

[0052] Figure 9B is a cross-sectional view of an embodiment of a positive electrode layer, an electrolyte layer, and a negative electrode layer; and

[0053] Figures 10A to 10J A diagram for explaining an embodiment of a method for manufacturing a secondary battery. DETAILED DESCRIPTION

[0054] Embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings, wherein the same reference numerals refer to the same elements throughout. In this regard, the present embodiment may have different forms and should not be construed as being limited to the description set forth herein. Therefore, the following description of the embodiments is merely to illustrate aspects of the present description by reference to the accompanying drawings. As used herein, the term "and / or" includes any and all combinations of one or more of the relevant enumerated items. Expressions such as "at least one (kind)" when preceding or following a list of elements modify the entire list of elements and do not modify the individual elements of the list.

[0055] It will be understood that when an element is referred to as being “on” another element, it can be directly on the other element or intervening elements may be present therebetween. In contrast, when an element is referred to as being “directly on” another element, there are no intervening elements present.

[0056] It will be understood that although the terms "first," "second," "third," etc., may be used herein to describe various elements, components, regions, layers, and / or portions, these elements, components, regions, layers, and / or portions should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, or portion from another element, component, region, layer, or portion. Thus, without departing from the teachings herein, a "first element," "component," "region," "layer," or "portion" discussed below may be referred to as a second element, component, region, layer, or portion.

[0057] The terms used herein are only used to describe the purpose of specific embodiments and are not intended to be restrictive. As used herein, "one (kind) (indefinite article) (a, an)", "said (the)" and "at least one (kind)" do not represent the limitation of quantity, and are intended to include both the singular and the plural, unless the context clearly indicates otherwise. For example, "(an) element" has the same meaning as "at least one element" unless the context clearly indicates otherwise. "At least one (kind)" will not be interpreted as limiting "one (kind)". "Or" means "and / or". It will be further understood that the terms "comprising" or "including" when used in this specification indicate the presence of stated features, regions, wholes, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, regions, wholes, steps, operations, elements, components, and / or their sets.

[0058] In addition, relative terms such as "lower" or "bottom" and "upper" or "top" may be used herein to describe the relationship of one element to another element as shown in the figures. It will be understood that relative terms are intended to include different orientations of the device in addition to the orientations depicted in the figures. For example, if the device in one of the figures is turned over, the element described as being on the "lower" side of the other element will be oriented on the "upper" side of the other element. Therefore, depending on the specific orientation of the figure, the exemplary term "lower" can cover both "lower" and "upper" orientations. Similarly, if the device in one of the figures is turned over, the element described as being "below" or "beneath" the other element will be oriented "above" the other element. Therefore, the exemplary terms "below" or "under" can cover both "above" and "below" orientations.

[0059] As used herein, "about" is inclusive of the stated value and means within an acceptable range of deviation for the particular value as determined by one of ordinary skill in the art, taking into account the measurements in question and the errors associated with the measurement of the particular quantity (i.e., the limitations of the measurement system). For example, "about" can mean within one or more standard deviations, or within ±30%, 20%, 10%, or 5% relative to the stated value.

[0060] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and this disclosure, and will not be interpreted in an idealized or overly formal sense unless clearly defined as such herein.

[0061] Exemplary embodiments are described herein with reference to cross-sectional views that are schematic representations of idealized embodiments. As such, deviations from the shapes of the figures are expected as a result of, for example, manufacturing techniques and / or tolerances. Therefore, the embodiments described herein should not be construed as limited to the specific shapes of the regions as shown herein, but rather include deviations in shape that result from, for example, manufacturing. For example, a region illustrated or described as flat may typically have rough and / or nonlinear features. Furthermore, illustrated sharp corners may be rounded. Therefore, the regions shown in the figures are schematic in nature, and their shapes are not intended to illustrate the precise shape of the regions and are not intended to limit the scope of the claims.

[0062] Hereinafter, a three-dimensional ("3D") electrode structure, a secondary battery including a 3D electrode structure, and a method for manufacturing a secondary battery will be described more fully with reference to the accompanying drawings. In the accompanying drawings, the widths and thicknesses of layers and regions are exaggerated for clarity of description and ease of illustration. Like reference numerals in the drawings represent like elements.

[0063] Figure 1A is a perspective view of a secondary battery 10 according to an embodiment. Figure 1B is a cross-sectional view of a secondary battery 10 according to an embodiment and Figure 1C for Figure 1B The enlarged part. Figure 1D 1 is a perspective view of a positive electrode layer 100 , an electrolyte layer 300 , and a first current collecting layer, for example, a first current collector 150 , included in a secondary battery 10 according to an embodiment. Figure 2A is a scanning electron microscope (“SEM”) image of the electrolyte layer 300 according to an embodiment. Figure 2B 1 and 2 are SEM images of the electrolyte layer 300 and the positive electrode layer 100 according to an embodiment.

[0064] refer to Figures 1A to 1D , the secondary battery 10 according to the embodiment may include: a first electrode structure E1 including a plurality of positive electrode layers 100 each having a flat plate shape, a second electrode structure E2 including a negative electrode layer 200, and an electrolyte layer 300 between the first electrode structure E1 and the second electrode structure E2. Figure 1A As shown in FIG, the structure of a secondary battery 10 may include a single (electrochemical) cell (or unit battery). The secondary battery 10 may have a stack structure in which a plurality of single (electrochemical) cells are stacked.

[0065] The first electrode structure E1 may include a first current collecting layer 150 and a plurality of positive electrode layers 100 electrically connected to the first current collecting layer 150. For example, each of the plurality of positive electrode layers 100 may have a flat plate shape. The plurality of positive electrode layers 100 may include a positive electrode active material. For example, the positive electrode active material may include an oxide containing Li. The Li-containing oxide may be an oxide containing Li and a transition metal. The Li-containing oxide may be, for example, LiMO2 (M is a metal), wherein M may be at least one of Co, Ni, Mn, or Al. For example, LiMO2 may be LiCoO2. The positive electrode active material may include a ceramic of a positive electrode component and may be polycrystalline or single crystal. For example, the Li-containing oxide may be, for example, LiMn2O4, LiFePO4, V2O5, Li3V2(PO4)3, or xLi2MnO3·(1-x)LiMO2 (wherein M is at least one of Co, Ni, Mn, or Al). However, the aforementioned materials of the positive electrode active material are exemplary, and various other positive electrode active materials may be used.

[0066] The first current collecting layer 150 may be a positive electrode current collector. The first current collecting layer 150 may have a plate shape and, in this case, may be referred to as a current collecting plate. The first current collecting layer 150 may include, for example, at least one of the following conductive materials: Cu, Au, Pt, Ag, Zn, Al, Mg, Ti, Fe, Co, Ni, Ge, In, Pd, Y, Zr, or Sn. The first current collecting layer 150 may be a metal layer or a layer including a conductive material other than metal.

[0067] Each positive electrode layer 100 having a flat plate shape may have, for example, two side surfaces having relatively wide, for example, large, surface areas, i.e., first and second side surfaces 101 and 102 facing each other, and may have third and fourth side surfaces 103 and 104 facing each other, each of which extends between the first and second side surfaces 101 and 102 and has a relatively smaller surface area than the first and second side surfaces 101 and 102. In other words, each of the third side surface 103 and the fourth side surface 104 may have a surface area smaller than each of the first side surface 101 and the second side surface 102. Two positive electrode layers 100 adjacent to each other may be arranged so that the first side surface 101 and the second side surface 102 face each other.

[0068] The electrolyte layer 300 may be disposed on the positive electrode layer 100 and the first current collecting layer 150. For example, the electrolyte layer 300 may include an amorphous solid electrolyte material 310 and a crystalline solid electrolyte including a plurality of crystalline solid electrolyte materials, such as particles 320. The amorphous solid electrolyte material 310 may be disposed on the first current collecting layer 150 and the outer surfaces, such as the outer surfaces, of the positive electrode layers 100 of the plurality of positive electrode layers 100, and the plurality of crystalline solid electrolyte materials 320 may be mixed within the amorphous solid electrolyte material 310. As used herein, the plurality of crystalline solid electrolyte materials 320 within the amorphous solid electrolyte material 310 means that the crystalline solid electrolyte material 320 is surrounded by the amorphous solid electrolyte material 310. As used herein, the outer surfaces or external surfaces of the positive electrode layers 100 of the plurality of positive electrode layers 100 refer to the surfaces of the positive electrode layers 100 of the plurality of positive electrode layers 100 excluding the surfaces of the positive electrode layers 100 of the plurality of positive electrode layers 100 that contact the first current collecting layer 150.

[0069] The amorphous solid electrolyte material 310 may have a winding form corresponding to the shape of the positive electrode layer 100. For example, the amorphous solid electrolyte material 310 may be arranged on at least the first side surface 101 and the second side surface 102 of the positive electrode layer 100, and may have a structure extending between the positive electrode layers 100 along the thickness direction of the positive electrode layer 100. However, the amorphous solid electrolyte material 310 may be arranged on the third and fourth side surfaces 103 and 104.

[0070] A plurality of crystalline solid electrolyte materials 320 may be mixed in a desired ratio within the amorphous solid electrolyte material 310. For example, the crystalline solid electrolyte, e.g., a plurality of crystalline solid electrolyte materials, e.g., particles 320, may be present in the electrolyte layer in an amount of about 10% to about 99% by volume based on the total volume of the electrolyte layer. In an embodiment, the crystalline solid electrolyte, e.g., a plurality of crystalline solid electrolyte materials, e.g., particles 320, may be present in the electrolyte layer in an amount of about 20% to about 95% by volume, 30% to about 90% by volume, 40% to about 85% by volume, or 50% to about 80% by volume based on the total volume of the electrolyte layer. For example, a plurality of crystalline solid electrolyte materials 320 may be mixed with an amorphous solid electrolyte material 310 and then formed through a low-temperature heat treatment, such as a heat treatment at about 700 degrees Celsius (° C.) or lower, such as about 50° C. to about 700° C., about 150° C. to about 600° C., or about 350° C. to about 500° C., so that the interface resistance between the plurality of crystalline solid electrolyte materials 320 and the amorphous solid electrolyte material 310 can be minimized. Therefore, the plurality of crystalline solid electrolyte materials 320 can increase the ionic conductivity of the electrolyte layer 300 including the amorphous solid electrolyte material 310 mixed with the plurality of crystalline solid electrolyte materials 320, which will be referred to later. Figures 3A to 6 Described in more detail.

[0071] As described herein, the electrolyte layer 300 may include a solid electrolyte material, i.e., an amorphous solid electrolyte material 310 and a plurality of crystalline solid electrolyte materials 320. For example, the amorphous solid electrolyte material 310 may include a solid electrolyte material such as Li 3+x La3M2O 12 (M is at least one of Te, Nb, or Zr, and 0 ≤ x ≤ 10), Li3PO4, Li x Ti y (PO4)3 (0 < x < 2 and 0 < y < 3), Li x Al y Ti z (PO4)3 (0 < x < 2, 0 < y < 1, and 0 < z < 3), Li 1+x+y (Al a Ga 1-a ) x (Ti b Ge 1-b ) 2-x Si y P 3- y O 12 (0 ≤ x ≤ 1, 0 ≤ y ≤ 1, 0 ≤ a ≤ 1, and 0 ≤ b ≤ 1), Li x La y TiO3 (0 < x < 2 and 0 < y < 3), based on Li x M y P z S w -based ceramics (M is at least one of Ge, Si, or Sn, 0 < x < 4, 0 < y < 1, 0 < z < 1, and 0 < w < 5), Li x N y (0 < x < 4 and 0 < y < 2), Li x PO y N z (0 < x < 4, 0 < y < 5, and 0 < z < 4), SiS2-based ceramics (Li x Si y S z , 0 < x < 3, 0 < y < 2, and 0 < z < 4), P2S5-based ceramics (Li x P y S z , 0 < x < 3, 0 < y < 3, and 0 < z < 7), Li2O, LiF, LiOH, Li2CO3, LiAlO2, Li2O-Al2O3-SiO2-P2O5-TiO2-GeO2-based ceramics, or based on Li x Lay M z O 12 ceramics of (M is at least one of Te, Nb, or Zr, 1 < x < 5, 0 < y < 4, and 0 < z < 4). For example, the plurality of crystalline solid electrolyte materials 320 may include solid electrolyte materials such as Li 3+x La3M2O 12 (M is at least one of Te, Nb, or Zr, and 0 ≤ x ≤ 10), Li3PO4, Li x Ti y (PO4)3(0 < x < 2 and 0 < y < 3), Li x Al y Ti z (PO4)3(0 < x < 2, 0 < y < 1, and 0 < z < 3), Li 1+x+y (Al a Ga 1-a ) x (Ti b Ge 1-b ) 2-x Si y P 3-y O 12 (0 ≤ x ≤ 1, 0 ≤ y ≤ 1, 0 ≤ a ≤ 1, and 0 ≤ b ≤ 1), Li x La y TiO3(0 < x < 2 and 0 < y < 3), based on Li x M y P z S w ceramics of (M is at least one of Ge, Si, or Sn, 0 < x < 4, 0 < y < 1, 0 < z < 1, and 0 < w < 5), Li x N y (0 < x < 4 and 0 < y < 2), Li x PO y N z (0 < x < 4, 0 < y < 5, and 0 < z < 4), based on SiS2 ceramics (Li x Si y S z , 0 < x < 3, 0 < y < 2, and 0 < z < 4), based on P2S5 ceramics (Li x P y S z , 0 < x < 3, 0 < y < 3, and 0 < z < 7), Li2O, LiF, LiOH, Li2CO3, LiAlO2, based on Li2O - Al2O3 - SiO2 - P2O5 - TiO2 - GeO2 ceramics, or based on Li x La y M z O12 ceramics (M is at least one of Te, Nb, or Zr, 1 < x < 5, 0 < y < 4, and 0 < z < 4). However, the materials and types of the amorphous solid electrolyte material 310 and the plurality of crystalline solid electrolyte materials 320 are not limited to those described herein and may vary.

[0072] The electrolyte layer 300 may be on the plurality of positive electrode layers 100, for example, surrounding the plurality of positive electrode layers 100. For example, the plurality of positive electrode layers 100 may be disposed on a surface of the first current collector layer 150, such as one surface, and may be perpendicular to the one surface of the first current collector layer 150. The electrolyte layer 300 surrounding each of the plurality of positive electrode layers 100 may have a width (or thickness) W and a length L greater than the width (thickness) W. For example, the electrolyte layer 300 may have a thickness W in the X-axis direction and may have a length L in the Y-axis direction perpendicular to the thickness W. The electrolyte layer 300 may have a height h in a direction perpendicular to the thickness direction (e.g., the X-axis direction) and the length direction (e.g., the Y-axis direction), i.e., in a direction perpendicular to the first current collector layer 150. In other words, the length of the electrolyte layer 300 in the Z-axis direction may be the height h. The height h may be greater than the thickness W and may be less than the length L. In other words, the positive electrode layers 100 may be spaced apart from each other in a first direction, such as the Figure 1A , Figure 1B , Figure 1C , and Figure 1D X-axis direction shown in, and as used herein, the thickness direction refers to the direction measured in the first direction.

[0073] For example, as Figure 2BAs shown in , the electrolyte layer 300 can be arranged on the surface of the positive electrode layer 100 of the plurality of positive electrode layers 100 to have a desired thickness, for example, a thickness W of about 100 nm to about 100 μm, for example, about 100 nm to about 90 μm, about 0.5 μm to about 80 μm, about 0.6 μm to about 70 μm, about 0.7 μm to about 60 μm, about 0.8 μm to about 50 μm, about 0.9 μm to about 40 μm, or about 1 μm to about 30 μm. For example, the plurality of crystalline solid electrolyte materials 320 may have an average particle size D of about 100 nm to about 100 μm, for example, about 100 nm to about 10 μm, about 200 nm to about 9 μm, about 300 nm to about 8 μm, about 400 nm to about 7 μm, about 500 nm to about 6 μm, about 600 nm to about 5 μm, or about 700 nm to about 4 μm. The electrolyte layer 300 may be formed by mixing the plurality of crystalline solid electrolyte materials 320 within the amorphous solid electrolyte material 310. The ratio of the average particle size D of the plurality of crystalline solid electrolyte materials 320 to the thickness W of the electrolyte layer 300 may be about 0.15:1 to about 0.25:1, for example, about 0.16:1 to about 0.24:1, about 0.17:1 to about 0.23:1, about 0.18:1 to about 0.22:1, or about 0.19:1 to about 0.21:1. When the average particle size D of the plurality of crystalline solid electrolyte materials 320 has a ratio as described herein to the thickness W of the electrolyte layer 300, the electrolyte layer 300 may have a thickness as described herein. Figure 2A . Therefore, the contact state between the electrolyte layer 300 and the positive electrode layer 100 and the negative electrode layer 200 arranged around the electrolyte layer 300 can be improved, and the generation of pores can be reduced or prevented, and the ion conductivity can also be improved. However, the aforementioned specific numbers for the thickness W of the electrolyte layer 300 and the average particle size D of the plurality of crystalline solid electrolyte materials 320 are merely exemplary.

[0074] The second electrode structure E2 may include a negative electrode layer 200 and a second current collecting layer 250 electrically connected to the negative electrode layer 200. The negative electrode layer 200 may include a negative electrode active material, and the second current collecting layer 250 may be a negative electrode current collecting layer. For example, the negative electrode active material included in the negative electrode layer 200 may include, for example, lithium metal, a carbon-based material, a silicon-based material, or an oxide. The negative electrode current collecting layer may include, for example, at least one conductive material such as Cu, Au, Pt, Ag, Zn, Al, Mg, Ti, Fe, Co, Ni, Ge, In, Pd, Y, Zr, or Sn. However, the materials of the negative electrode active material and the negative electrode current collecting layer are not limited thereto.

[0075] The second current collecting layer 250 may face the first current collecting layer 150. The negative electrode layer 200 may have a winding form corresponding to the shape of the positive electrode layer 100 while electrically contacting the second current collecting layer 250. For example, the negative electrode layer 200 may be arranged on at least the first side surface 101 and the second side surface 102 of the positive electrode layer 100 and may have a structure extending between the positive electrode layers 100 along the thickness direction of the positive electrode layer 100. In this case, the portion of the negative electrode layer 200 extending between the positive electrode layers 100 may have a plate shape. Therefore, the portion of the negative electrode layer 200 extending between the positive electrode layers 100 may be referred to as "a plurality of negative electrode layer plates". In this case, the positive electrode layers 100 and the negative electrode layer plates may alternate with each other. The electrolyte layer 300 may be arranged between the positive electrode layer 100 and the negative electrode layer 200.

[0076] The secondary battery 10 may include: a first electrode structure E1 as a 3D structure including a plurality of positive electrode layers 100 perpendicular (or substantially perpendicular) to a first current collecting layer 150, and a second electrode structure E2 including a negative electrode layer 200 and a second current collecting layer 250, and compared to a secondary battery including a two-dimensional ("2D") electrode structure (i.e., a planar structure), the capacity and energy density of the secondary battery 10 may be greatly increased. When compared to a planar electrode structure, the 3D electrode structure may provide a high, for example, large, volume of active material, for example, the volume of a crystalline solid electrolyte present in the electrolyte layer, and a wide, for example, large, reaction surface area, and the 3D electrode structure may be advantageous for improving the energy density and rate performance of the battery (secondary battery).

[0077] However, when the positive electrode active material included in the positive electrode layer 100 is sintered to a high density to increase the capacity of the secondary battery 10, the ionic conductivity of the positive electrode layer 100 may be reduced, and the energy density and rate performance of the secondary battery 10 may be reduced. The secondary battery 10 in which the ionic conductivity of the positive electrode layer 100 is increased by arranging the amorphous solid electrolyte material 310 and the plurality of crystalline solid electrolyte materials in the electrolyte layer 300 will now be described in more detail.

[0078] Figure 3A is a cross-sectional view of a secondary battery according to Comparative Example 1 and Figure 3B for Figure 3A The enlarged part. Figure 3C is a SEM image of the electrolyte layer 301 according to Comparative Example 1. Figure 4A is a cross-sectional view of a secondary battery according to Comparative Example 2 and Figure 4B for Figure 4A The enlarged part. Figure 4C is a SEM image of the electrolyte layer 302 according to Comparative Example 2. Figure 5 is a graph showing the relationship between the heat treatment process temperature of the electrolyte layer and its ion conductivity. Figure 6Nyquist plots representing the ionic conductivity of Comparative Example 1, Comparative Example 2, and a hybrid LLZO embodiment.

[0079] refer to Figure 3A 、 Figure 3B and Figure 3C The positive electrode layer 100 according to Comparative Example 1 can be formed by drying the active material slurry to form an active material sheet, and sintering the positive electrode active material, such as LiCoO2 ("LCO"), included in the active material sheet through a sintering process. On the positive electrode layer 100 obtained by sintering the positive electrode active material, a plurality of crystalline solid electrolyte materials 320, such as crystalline Li7La3Zr2O 12 ("LLZO") powders may be arranged in a pressing (extrusion) manner, for example, in a manner of being pressed against each other. A high-temperature heat treatment may be applied to the plurality of crystalline solid electrolyte materials 320, for example, a heat treatment at a high temperature of about 1,000°C or greater, for example, about 1,000°C to about 3,000°C, about 1,200 to about 2,800°C, or about 1,400 to about 2,600°C. In this case, an interfacial decomposition reaction may be generated between the positive electrode active material included in the positive electrode layer 100 and the plurality of crystalline solid electrolyte materials 320, and a reaction product (for example, Li2CoO4 or LaCoO3) obtained due to the generated interfacial decomposition reaction may greatly increase the interface resistance. Therefore, as Figure 5 As shown in , when the electrolyte layer 301 includes only a plurality of crystalline solid electrolyte materials 320 , the crystalline solid electrolyte layer may not be suitable for use as the electrolyte layer 300 in a 3D secondary battery.

[0080] refer to Figure 4A 、 Figure 4B and Figure 4C The positive electrode layer 100 according to Comparative Example 2 can be formed by drying an active material slurry to form an active material sheet, and sintering a positive electrode active material, such as LiCoO2 ("LCO"), included in the active material sheet through a sintering process. On the positive electrode layer 100 obtained by sintering the positive electrode active material, the amorphous solid electrolyte material 310 can be disposed along the sidewall of the positive electrode layer 100 by using a spin coating method. For example, for amorphous Li7La3Zr2O 12 ("LLZO") precursor liquid mixture. For example, the amorphous solid electrolyte material 310 may be subjected to a low-temperature heat treatment, such as a heat treatment at a low temperature of 700°C or lower, such as about 50°C to about 700°C, about 150°C to about 600°C, or about 350°C to about 500°C. For example, the amorphous solid electrolyte material 310 formed as in Comparative Example 2 may include an ionic conductivity lower than that of the crystalline solid electrolyte material 320, such as Figure 5 As shown in .

[0081] like Figure 1B and Figure 1C As shown in , the electrolyte layer 300 according to the embodiment may include a crystalline solid electrolyte material 320 including relatively high ionic conductivity, and a plurality of crystalline solid electrolyte materials 320 may be mixed in the amorphous solid electrolyte material 310. In this case, the amorphous solid electrolyte material 310 and the plurality of crystalline solid electrolyte materials 320 may be subjected to low-temperature heat treatment, for example, heat treatment at a low temperature of 700° C. or lower, for example, about 50° C. to about 700° C., about 150° C. to about 600° C., or about 350° C. to about 500° C. The electrolyte layer 300 according to the embodiment may include an ionic conductivity higher than that of Comparative Examples 1 and 2, for example, about 10 -6 S / cm or more, for example, about 10 -6 S / cm-about 10 -4 S / cm, about 10 -6 S / cm-about 5×10 -5 S / cm, or about 5×10 -6 S / cm-about 1×10 -5 S / cm ion conductivity.

[0082] refer to Figure 6 , the resistance of the following comparative example is shown as a graph: wherein the crystallized Li7La3Zr2O 12 ("LLZO") powder is placed on the positive electrode layer 100 in a pressed manner and is not subjected to a special heat treatment. 12 In the case of amorphous Li7La3Zr2O powder, a non-conductive state in which no ionic conductivity was measured was confirmed. 12 A liquid mixture of a precursor of Li7La3Zr2O is placed along the sidewall of the positive electrode layer 100 by a spin coating method, and subjected to a low temperature heat treatment, for example, a heat treatment at a low temperature of 700°C or lower, for example, about 50°C to about 700°C, about 150°C to about 600°C, or about 350°C to about 500°C. 12 In the case where the precursor liquid mixture of LLZO ("LLZO") is disposed along the sidewall of the positive electrode layer 100 by a spin coating method, it can be confirmed that the amorphous solid electrolyte layer includes about 6.98×10 -7 The ionic conductivity of S / cm is shown as a graph of the resistance of the following case according to the embodiment: wherein crystallized Li7La3Zr2O 12 ("LLZO") powder and amorphous Li7La3Zr2O 12("LLZO") is mixed with a precursor liquid mixture and then arranged along the sidewall of the positive electrode layer 100 according to a spin coating method, and a low-temperature heat treatment is performed, for example, a heat treatment at a low temperature of 700° C. or lower, for example, about 50° C. to about 700° C., about 150° C. to about 600° C., or about 350° C. to about 500° C. According to an embodiment, it can be confirmed that the electrolyte layer 300 according to an embodiment may include about 1.44×10 -6 S / cm, and the electrolyte layer 300 according to the embodiment may include relatively high ion conductivity.

[0083] Figure 7 is a cross-sectional view of the positive electrode layer 100 , the electrolyte layer 300 , and the first current collecting layer 150 according to an embodiment.

[0084] refer to Figure 7 , the thickness W of the uppermost end of the electrolyte layer 300 in the height direction (Z-axis direction) t Relative to the thickness W of the bottom end of the electrolyte layer 300 b The ratio of the positive electrode layer 100 to the positive electrode layer 100 may be about 0.1:1 to about 1:1, for example, about 0.2:1 to about 0.9:1, about 0.3:1 to about 0.8:1, or about 0.4:1 to about 0.7:1. For example, as the distance from the first current collecting layer 150 in the height direction (Z-axis direction) increases, non-uniform charge and discharge due to the electric polarization of the positive electrode layer 100 may occur. For example, when Ni, Mn, Al, etc. having low electrical conductivity replaces the LiCo in the position of Co, the positive electrode layer 100 may be charged and discharged. 1-x M x When an NCA or NCM material of O2 is included as a positive electrode active material included in the positive electrode layer 10, overcharge may occur at the lower portion of the positive electrode layer 100 adjacent to the first current collecting layer 150, and degradation caused by the overcharge, such as phase change, may occur. In order to reduce or prevent degradation due to overcharge, the thickness W of the lowermost portion of the electrolyte layer 300 surrounding the positive electrode layer 100 is preferably 0.1mm. b It may be formed to be greater than the thickness W of the uppermost portion of the electrolyte layer 300. t When the thickness W of the lowermost portion of the electrolyte layer 300 is b is formed to be larger than the thickness W of the uppermost portion of the electrolyte layer 300 t When the positive electrode layer 100 is charged and discharged, the delithiation polarization may be formed in the corresponding lower portion of the positive electrode layer 100, and thus, uniform charge and discharge may be possible in the corresponding upper and lower portions of the positive electrode layer 100. As used herein, the uppermost end of the electrolyte layer 300 refers to the end of the electrolyte layer 300 that is farther from the positive electrode current collector 150 than the lowermost end of the electrolyte layer 300 in a second direction perpendicular to the first direction, such as the X-axis direction, such as the Z-axis direction.

[0085] Figure 8is a cross-sectional view of a positive electrode layer 100 and an electrolyte layer 300 according to an embodiment. Figure 9A is a cross-sectional view of a positive electrode layer 100, an electrolyte layer 300, and a negative electrode layer 200 according to an embodiment. Figure 9B is a cross-sectional view of a positive electrode layer 100, an electrolyte layer 300, and a negative electrode layer 200 according to an embodiment.

[0086] As described herein, the electrolyte layer 300 according to the embodiment may include a solid electrolyte material, that is, an amorphous solid electrolyte material 310 and a plurality of crystalline solid electrolyte materials 320. For example, by changing the type of the crystalline solid electrolyte material 320 or the thickness of the amorphous solid electrolyte material 310, etc., the uniformity of the electrolyte layer 300 may be changed.

[0087] refer to Figure 8 , the electrolyte layer 300 may include a plurality of crystalline solid electrolyte materials having different particle sizes from one another. For example, the electrolyte layer 300 may include a first crystalline solid electrolyte material 321 and a second crystalline solid electrolyte material 322, and the first crystalline solid electrolyte material 321 and the second crystalline solid electrolyte material 322 may be formed of the same material. However, the first crystalline solid electrolyte material 321 and the second crystalline solid electrolyte material 322 may be formed of different materials. For example, the electrolyte layer 300 may include a first crystalline solid electrolyte material 321 having a first average particle size D1 and a second crystalline solid electrolyte material 322 having a second average particle size D2. For example, the ratio of the second average particle size D2 of the second crystalline solid electrolyte material 322 to the first average particle size D1 of the first crystalline solid electrolyte material 321 may be about 0.05 to about 0.5, such as about 0.06 to about 0.45, about 0.07 to about 0.40, about 0.08 to about 0.35, about 0.09 to about 0.30, about 0.10 to about 0.25, or about 0.11 to about 0.20. When the first crystalline solid electrolyte material 321 and the second crystalline solid electrolyte material 322 having different average particle sizes as described herein are mixed and arranged, the second crystalline solid electrolyte material 322 having a relatively small average particle size may be arranged between the first crystalline solid electrolyte material 321 having a relatively large average particle size. Therefore, the second crystalline solid electrolyte material 322 between the first crystalline solid electrolyte materials 321 can connect the first crystalline solid electrolyte materials 321 to each other to thereby reduce the interface resistance.

[0088] refer to Figure 9AThe electrolyte layer 300 may include a first amorphous solid electrolyte material layer 340 surrounding the positive electrode layer 100, a mixed solid electrolyte material layer 360 surrounding the first amorphous solid electrolyte material layer 340 and obtained by mixing a plurality of third crystalline solid electrolyte materials 323 in the second amorphous solid electrolyte material 330, and a third amorphous solid electrolyte material layer 350 surrounding the mixed solid electrolyte material layer 360.

[0089] When the electrolyte layer 300 including the crystalline solid electrolyte material 320 is as Figure 1B and Figure 1C When the electrolyte layer 300 is arranged along the side wall of the positive electrode layer 100 arranged perpendicular to the first current collecting layer 150 as shown in FIG, due to gravity and difficulties in the pressing process, it may be difficult for the electrolyte layer 300 to be evenly arranged along the side wall of the positive electrode layer 100. When non-uniform arrangement and openings are generated between the positive electrode layer 100 and the electrolyte layer 300 and between the electrolyte layer 300 and the negative electrode layer 200, the secondary battery may be non-uniformly charged and discharged. In order to achieve uniform contact between the positive electrode layer 100, the electrolyte layer 300 and the negative electrode layer 200, the electrolyte layer 300 may be formed to have a multi-layer structure.

[0090] As used herein, the first amorphous solid electrolyte material layer 340 of the electrolyte layer 300 that may surround the positive electrode layer 100 may not include a crystalline solid electrolyte material. Therefore, the opening that may be generated in the contact surface between the positive electrode layer 100 and the first amorphous solid electrolyte material layer 340 may be minimized. The third amorphous solid electrolyte material layer 350 that may be surrounded by the negative electrode layer 200 may not include a crystalline solid electrolyte material. Therefore, the opening that may be generated in the contact surface between the negative electrode layer 200 and the third amorphous solid electrolyte material layer 350 may be minimized.

[0091] The mixed solid electrolyte material layer 360 may be disposed between the first amorphous solid electrolyte material layer 340 and the third amorphous solid electrolyte material layer 350 such that the plurality of third crystalline solid electrolyte materials 323 are mixed in the second amorphous solid electrolyte material 330. A ratio of an average particle size D3 of the plurality of third crystalline solid electrolyte materials 323 to a thickness W1 of the first amorphous solid electrolyte material layer 340 may be in a range from about 0.5:1 to about 1:1, e.g., from about 0.55:1 to about 0.95:1, from about 0.60:1 to about 0.90:1, or from about 0.65:1 to about 0.85:1. The ratio of the average particle size D3 of the plurality of third crystalline solid electrolyte materials 323 to the thickness W2 of the third amorphous solid electrolyte material layer 350 may be about 0.5:1 to about 1:1, for example, about 0.55:1 to about 0.95:1, about 0.60:1 to about 0.90:1, or about 0.65:1 to about 0.85:1. The mixed solid electrolyte material layer 360 may be arranged between the first amorphous solid electrolyte material layer 340 and the third amorphous solid electrolyte material layer 350 as described herein, and the ionic conductivity of the electrolyte layer 300 may be improved. The electrolyte layer 300 may have a multilayer structure as described herein, the openings of the electrolyte layer 300 to the positive electrode layer 100 and the negative electrode layer 200 may be minimized, and the ionic conductivity may be improved.

[0092] refer to Figure 9B , the electrolyte layer 300 may include a first amorphous solid electrolyte material layer 340 surrounding the positive electrode layer 100, a mixed solid electrolyte material layer 360 surrounding the first amorphous solid electrolyte material layer 340 and obtained by mixing a plurality of third crystalline solid electrolyte materials 323 in the second amorphous solid electrolyte material 330, a third amorphous solid electrolyte material layer 350 surrounding the mixed solid electrolyte material layer 360, and a plurality of fourth crystalline solid electrolyte materials 325 arranged in at least one of the first amorphous solid electrolyte material layer 340, the second amorphous solid electrolyte material 330, or the third amorphous solid electrolyte material layer 350.

[0093] For example, the third crystalline solid electrolyte material 323 and the fourth crystalline solid electrolyte material 325 can be the same material. However, the third crystalline solid electrolyte material 323 and the fourth crystalline solid electrolyte material 325 can be different materials. For example, the third crystalline solid electrolyte material 323 can have a third average particle size D3, and the fourth crystalline solid electrolyte material 325 can have a fourth average particle size D4. For example, the ratio of the fourth average particle size D4 of the fourth crystalline solid electrolyte material 325 to the third average particle size D3 of the third crystalline solid electrolyte material 323 can be from about 0.05:1 to about 0.3:1, such as from about 0.06:1 to about 0.25:1, from about 0.07:1 to about 0.20:1, or from about 0.08:1 to about 0.15:1. When the third crystalline solid electrolyte material 323 and the fourth crystalline solid electrolyte material 325 having different average particle sizes as described herein are mixed and arranged, the fourth crystalline solid electrolyte material 325 having a relatively small average particle size may be arranged between the third crystalline solid electrolyte materials 323 having a relatively large average particle size. The fourth crystalline solid electrolyte material 325 between the third crystalline solid electrolyte materials 323 may connect the third crystalline solid electrolyte materials 323 to each other to thereby reduce interface resistance.

[0094] When the fourth crystalline solid electrolyte material 325 having a relatively small average particle size is disposed between the first amorphous solid electrolyte material layer 340 and the second amorphous solid electrolyte material layer 330, relatively constant surface uniformity of the electrolyte layer 300 facing the positive electrode layer 100 and the negative electrode layer 200 can be maintained, and the generation of openings between the positive electrode layer 100 and the negative electrode layer 200 and the electrolyte layer 300 can be reduced or prevented. In addition, the fourth crystalline solid electrolyte material 325 can be disposed between the first amorphous solid electrolyte material layer 340 and the second amorphous solid electrolyte material layer 330, and ionic conductivity can be improved.

[0095] Figures 10A to 10J 1 and 2 are diagrams for explaining a method of manufacturing a secondary battery according to an embodiment.

[0096] refer to Figure 10A , a first electrode structure E1 may be provided by arranging a plurality of positive electrode layers 100 having a flat plate shape on a first current collecting layer 150. For example, the first electrode structure E1 has a shape corresponding to Figure 1A The positive electrode layer 100 can be formed by drying an active material slurry to form an active material sheet, and sintering the positive electrode active material included in the active material sheet through a sintering process. The active material slurry can be prepared by mixing, for example, a positive electrode active material (powder), a binder, a dispersant, a plasticizer, etc. with a solvent. The mixing can be performed using a grinding machine such as a ball mill or a mixing device.

[0097] Next, refer to Figure 10B 、 Figure 10C and Figure 10D After coating the first amorphous solid electrolyte material 311 on the first electrode structure E1, the electrolyte layer 300 may be formed by using a spin coating process. For example, the first amorphous solid electrolyte material 311 may be a solid electrolyte, for example, for amorphous Li7La3Zr2O 12 ("LLZO") precursor liquid mixture, and the first amorphous solid electrolyte material 311 may be in the form of a sol. The 3D electrode structure may have an open structure in which a plurality of positive electrode layers 100 are spaced apart in the width direction and the length direction, and the first amorphous solid electrolyte material 311 can be easily formed by spin coating.

[0098] After coating the first amorphous solid electrolyte material 311, the first amorphous solid electrolyte material 311 may be subjected to a first heat treatment. The first heat treatment may be performed in a pressed state at a low temperature of about 700° C. or less, for example, about 50° C. to about 700° C., about 150° C. to about 600° C., or about 350° C. to about 500° C., and the interface resistance may be reduced without damaging the positive electrode layer 100, and thus, the ion conductivity may be improved.

[0099] Next, refer to Figure 10E 、 Figure 10F and Figure 10G , after the second amorphous solid electrolyte material 312 and the plurality of crystalline solid electrolyte materials 320 are coated on the first electrode structure E1, the electrolyte layer 300 may be formed by using a spin coating process. For example, the second amorphous solid electrolyte material 312 may be a solid electrolyte, for example, a precursor liquid mixture for amorphous LLZO, and the plurality of crystalline solid electrolyte materials 320 may be crystalline LLZO powder. The second amorphous solid electrolyte material 312 may be in the form of a sol, and the plurality of crystalline solid electrolyte materials 320 may be mixed within the second amorphous solid electrolyte material 312. The 3D electrode structure may have an open structure in which the plurality of positive electrode layers 100 are spaced apart in the width direction and the length direction, and the second amorphous solid electrolyte material 312 and the plurality of crystalline solid electrolyte materials 320 may be easily formed by spin coating. By coating the second amorphous solid electrolyte material 312 and the plurality of crystalline solid electrolyte materials 320, it may be possible as Figure 10F and Figure 10G As shown in FIG, a structure in which a plurality of crystalline solid electrolyte materials 320 and amorphous solid electrolyte materials 310 are mixed is formed.

[0100] After coating the second amorphous solid electrolyte material 312 and the plurality of crystalline solid electrolyte materials 320, the second amorphous solid electrolyte material 312 and the plurality of crystalline solid electrolyte materials 320 may be subjected to a second heat treatment. The second heat treatment may be performed in a pressed state at a low temperature of 700°C or less, for example, about 50°C to about 700°C, about 150°C to about 600°C, or about 350°C to about 500°C, and the interface resistance between the amorphous solid electrolyte material 310 and the plurality of crystalline solid electrolyte materials 320 may be reduced without damaging the positive electrode layer 100, and thus, the ion conductivity may be improved.

[0101] Next, refer to Figure 10H 、 Figure 10I and Figure 10J After coating the third amorphous solid electrolyte material 313 on the first electrode structure E1, the electrolyte layer 300 may be formed by using a spin coating process. For example, the third amorphous solid electrolyte material 313 may be a solid electrolyte, for example, a precursor liquid mixture for amorphous LLZO, and may be in the form of a sol. The third amorphous solid electrolyte material 313 may be coated on the plurality of crystalline solid electrolyte materials 320, and the plurality of crystalline solid electrolyte materials 320 may be arranged to be mixed in the amorphous solid electrolyte material 310, as shown in FIG. Figure 10I and Figure 10J As shown in .

[0102] After coating the third amorphous solid electrolyte material 313, the third amorphous solid electrolyte material 313 may be subjected to a third heat treatment. The third heat treatment may be performed in a pressed state at a low temperature of 700° C. or less, for example, about 50° C. to about 700° C., about 150° C. to about 600° C., or about 350° C. to about 500° C., and the interface resistance between the amorphous solid electrolyte material 310 and the plurality of crystalline solid electrolyte materials 320 may be reduced without damaging the positive electrode layer 100, and thus, the ion conductivity may be improved.

[0103] Although the first amorphous solid electrolyte material 311, the second amorphous solid electrolyte material 312 and the mixture of multiple crystalline solid electrolyte materials 320, and the third amorphous solid electrolyte material 313 have been described herein as being formed by spin coating, dip coating can be used instead of spin coating. The amorphous solid electrolyte material 310 can be formed by using a deposition method such as atomic layer deposition ("ALD"), chemical vapor deposition ("CVD"), or physical vapor deposition ("PVD"). The coating of the first amorphous solid electrolyte material 311 can be performed multiple times, for example, two to five times, using a layer-by-layer ("LBL") method.

[0104] Next, the secondary battery 10 according to the embodiment can be manufactured as follows: a negative electrode layer 200 and a second current collecting layer 250 are sequentially formed on the electrolyte layer 300, and the negative electrode layer 200 includes a negative electrode active material. For example, the negative electrode active material included in the negative electrode layer 200 may include, for example, Li metal, a carbon-based material, a silicon-based material, or an oxide. The second current collecting layer 250 may include, for example, at least one conductive material as follows: Cu, Au, Pt, Ag, Zn, Al, Mg, Ti, Fe, Co, Ni, Ge, In, or Pd. For example, the negative electrode layer 200 can be formed by coating the negative electrode active material on the electrolyte layer 300. The second current collecting layer 250 can be provided to face the first current collecting layer 150. The secondary battery 10 may be, for example, a Li secondary battery.

[0105] A secondary battery can be provided, comprising a positive electrode layer and an electrolyte layer in which ions can easily move. A secondary battery can be provided that does not exhibit capacity reduction even at high rates. A secondary battery that can be usefully applied to a variety of electronic devices including mobile devices and wearable devices can be provided.

[0106] It should be understood that the embodiments described herein should be considered in a descriptive sense only and not for purposes of limitation. The description of features or aspects in each embodiment should be considered applicable to other similar features or aspects in other embodiments. Although the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the appended claims.

Claims

1. A solid electrolyte-positive electrode assembly for a secondary battery, comprising: a plurality of positive electrode layers spaced apart from each other in a first direction; as well as an electrolyte layer comprising: amorphous solid electrolytes, and a crystalline solid electrolyte comprising a plurality of crystalline solid electrolyte particles, wherein the amorphous solid electrolyte is on a surface of a positive electrode layer of the plurality of positive electrode layers and the crystalline solid electrolyte is within the amorphous solid electrolyte, wherein a ratio of an average particle size of the plurality of crystalline solid electrolyte particles to a thickness of the electrolyte layer measured in the first direction is 0.15:1 to 0.25:

1. 2 . The solid electrolyte-cathode assembly of claim 1 , wherein the crystalline solid electrolyte is present in the electrolyte layer in an amount of 10 volume percent to 99 volume percent based on the total volume of the electrolyte layer. 3 . The solid electrolyte-cathode assembly of claim 1 , wherein the thickness of the electrolyte layer measured in the first direction is 100 nanometers to 100 micrometers. 4 . The solid electrolyte-cathode assembly of claim 1 , wherein the plurality of crystalline solid electrolyte particles have an average particle size of 100 nanometers to 100 micrometers.

5. The solid electrolyte-positive electrode assembly of claim 1 , further comprising: a positive electrode current collector facing an end of each of the plurality of positive electrode layers and contacting a portion of each of the plurality of positive electrode layers, The surfaces of the positive electrode layers of the plurality of positive electrode layers on which the amorphous solid electrolyte material exists are different from respective ends of the plurality of positive electrode layers facing the positive electrode current collector.

6. The solid electrolyte-positive electrode assembly of claim 1 , wherein each of the plurality of positive electrode layers comprises a first surface and a second surface opposite to each other, and a third surface and a fourth surface each extending between the first surface and the second surface, wherein the third surface and the fourth surface each have a surface area that is smaller than the surface area of ​​each of the first surface and the second surface, wherein the third surface and the fourth surface are opposite to each other, and A first surface of the first positive electrode layer and a second surface of a second positive electrode layer adjacent to the first positive electrode layer face each other. 7 . The solid electrolyte-positive electrode assembly of claim 6 , wherein the electrolyte layer is on the first surface and the second surface of each of the plurality of positive electrode layers.

8. The solid electrolyte-positive electrode assembly according to claim 1, wherein The thickness (W) of the uppermost end of the electrolyte layer measured in the first direction t ) for the thickness (W) of the lowermost end of the electrolyte layer measured in the first direction b ) ratio is 0.1:1-1:1, The solid electrolyte-positive electrode assembly further includes a positive electrode current collector, and the plurality of positive electrode layers are arranged on the positive electrode current collector.

9. The solid electrolyte-cathode assembly of claim 1 , wherein the crystalline solid electrolyte comprises first crystalline solid electrolyte particles and second crystalline solid electrolyte particles having different average particle sizes, and The ratio of the average particle size of the first crystalline solid electrolyte particles to the average particle size of the second crystalline solid electrolyte particles is 0.05:1 to 0.5:

1.

10. The solid electrolyte-positive electrode assembly according to claim 1, wherein the ionic conductivity of the electrolyte layer is 10 -6 Siemens / cm-10 -4 Siemens / cm.

11. The solid electrolyte-positive electrode assembly according to claim 1, wherein the electrolyte layer is a product of heat treatment at a temperature of 50°C to 700°C.

12. The solid electrolyte-cathode assembly of claim 1, wherein the crystalline solid electrolyte comprises Li 3+ x La3M2O 12 , wherein M is at least one of Te, Nb or Zr, and 0≤x≤10.

13. The solid electrolyte-cathode assembly of claim 1, wherein the amorphous solid electrolyte comprises Li 3+ x La3M2O 12 , wherein M is at least one of Te, Nb or Zr, and 0≤x≤10.

14. Solid electrolyte-cathode assembly, comprising: a plurality of positive electrode layers spaced apart from each other in a first direction; and an electrolyte layer on a surface of a positive electrode layer of the plurality of positive electrode layers; The electrolyte layer comprises: a first amorphous solid electrolyte layer on the positive electrode layer of the plurality of positive electrode layers; a hybrid solid electrolyte layer on the first amorphous solid electrolyte layer, the hybrid solid electrolyte layer comprising a plurality of third crystalline solid electrolyte particles in a second amorphous solid electrolyte; and a third amorphous solid electrolyte layer on the mixed solid electrolyte layer, wherein a ratio of an average particle size of the plurality of third crystalline solid electrolyte particles to a thickness of the first amorphous solid electrolyte layer measured in the first direction is 0.5:1-1:

1. 15 . The solid electrolyte-cathode assembly of claim 14 , wherein a ratio of an average particle size of the plurality of third crystalline solid electrolyte particles to a thickness of the third amorphous solid electrolyte layer measured in the first direction is 0.5:1 to 1:

1.

16. The solid electrolyte-cathode assembly of claim 14, wherein a plurality of fourth crystalline solid electrolyte particles are in at least one of the first amorphous solid electrolyte layer, the hybrid solid electrolyte layer, or the third amorphous solid electrolyte layer. 17 . The solid electrolyte-cathode assembly of claim 16 , wherein a ratio of an average particle size of the plurality of fourth crystalline solid electrolyte particles to an average particle size of the plurality of third crystalline solid electrolyte particles is 0.05:1 to 0.3:

1.

18. Secondary batteries, including: A negative electrode layer on the solid electrolyte-positive electrode assembly according to any one of claims 1 to 17.

19. A method for manufacturing a solid electrolyte-positive electrode assembly for a secondary battery according to any one of claims 1 to 17, the method comprising: a plurality of positive electrode layers arranged on the positive electrode current collector and spaced apart from each other in a first direction; coating a first amorphous solid electrolyte on the positive electrode layer of the plurality of positive electrode layers to provide a first amorphous solid electrolyte-coated positive electrode layer; heat-treating the first amorphous solid electrolyte-coated positive electrode layer to provide a heat-treated first amorphous solid electrolyte-coated positive electrode layer; coating a mixture of a second amorphous solid electrolyte and a crystalline solid electrolyte including a plurality of crystalline solid electrolyte particles on the heat-treated first amorphous solid electrolyte-coated positive electrode layer to provide a coated mixture; heat treating the coated mixture to provide a heat-treated mixture; coating a third amorphous solid electrolyte on the heat-treated mixture to provide an amorphous solid electrolyte material; and The amorphous solid electrolyte material is heat-treated to produce the solid electrolyte-positive electrode assembly.

20. The method of claim 19, wherein Heat treating the first amorphous solid electrolyte coated cathode layer, heat treating the coated mixture, or heat treating the amorphous solid electrolyte material each independently includes heat treating at 50°C to 700°C. 21 . The method of claim 20 , wherein coating the first amorphous solid electrolyte, the mixture of the second amorphous solid electrolyte and the crystalline solid electrolyte, or the third amorphous solid electrolyte each independently comprises spin coating or dip coating.

22. A method for manufacturing a secondary battery, the method comprising: providing a negative electrode layer; Providing a solid electrolyte-positive electrode assembly according to any one of claims 1 to 17; and The negative electrode layer is provided on the solid electrolyte-positive electrode assembly to manufacture the secondary battery.

23. An electrolyte layer of a secondary battery, comprising: an amorphous solid electrolyte; and multiple crystalline solid electrolyte particles, wherein the electrolyte layer has a thickness of 100 nanometers to 100 micrometers, wherein the plurality of crystalline solid electrolyte particles have an average particle size of 100 nanometers to 100 micrometers, and wherein the ratio of the average particle size of the plurality of crystalline solid electrolyte particles to the thickness of the electrolyte layer is 0.15:1-0.25:1, wherein the amorphous solid electrolyte is on a surface of a positive electrode layer and the crystalline solid electrolyte particles are within the amorphous solid electrolyte.

Images