KR20210136823A - Secondary battery and method of manufacturing the same - Google Patents

Abstract

The present invention relates to a secondary battery and a method for manufacturing the same. A secondary battery, according to an embodiment of the present invention, comprises: a positive electrode layer comprising a positive electrode active material layer; a negative electrode layer comprising a negative electrode current collector and a metal layer disposed on the negative electrode current collector; a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer; and a graphite-based interlayer disposed between the solid electrolyte layer and the negative electrode layer. A crystalline material included in a graphite-based material in the graphite-based interlayer has a size (La) of 1,000 angstrom or more measured by 110 diffraction rays using X-ray diffraction. The interplanar spacing (Lc) of hexagonal mesh planes in the c-axis direction measured by 002 diffraction rays using the X-ray diffraction method is 500 or more, and the aspect ratio maybe 0.44 or more and 0.55 or more. The present invention provides a secondary battery having excellent performance and is capable of preventing a short circuit that may be caused by lithium (metal lithium) deposited on the negative electrode side during the charging of the secondary battery.

Description

Secondary battery and method of manufacturing the secondary battery {Secondary battery and method of manufacturing the same}

The disclosed embodiments relate to a secondary battery and a method of manufacturing the secondary battery.

Recently, an all-solid-state secondary battery using a solid electrolyte as an electrolyte is attracting attention. In order to increase the energy density of such a solid secondary battery, it is proposed to use lithium as an anode active material. For example, it is known that the capacity density (capacity per unit mass) of lithium is about 10 times that of graphite generally used as an anode active material. Therefore, it is possible to increase the output while reducing the thickness of the solid secondary battery by using lithium as an anode active material.

Provided is a secondary battery having excellent performance capable of preventing a short circuit that may be caused by lithium (metal lithium) deposited on an anode side during charging of the secondary battery.

A secondary battery having excellent charge and discharge characteristics is provided.

A secondary battery advantageous in terms of process easiness and manufacturing cost is provided.

이상 1500

이하 이며, 엑스선 회절법을 이용한 002회절선에 의해 측정되는 c축 방향의 육각망면 면간격 (Lc)이 500

이상 800

이하 이며, 종횡비(aspect ratio)가 0.44이상 0.55이상인,이차 전지를 제공할 수 있다.According to one aspect (aspect), the negative electrode layer including a positive electrode layer including a positive electrode active material layer, a negative electrode current collector and a metal layer disposed on the negative electrode current collector; and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer. and a graphite-based interlayer disposed between the solid electrolyte layer and the negative electrode layer, wherein the graphite-based interlayer includes a graphite-based material, and the graphite-based material includes The crystallinity of the graphite-based material has a crystallite size (La) of 1000 measured by 110 diffraction rays using an X-ray diffraction method.

more than 1500

Below, the interplanar spacing (Lc) of hexagonal mesh planes in the c-axis direction measured by 002 diffraction ray using X-ray diffraction method is 500

more than 800

or less, and having an aspect ratio of 0.44 or more and 0.55 or more, it is possible to provide a secondary battery.

The metal layer may include at least one of lithium or a lithium alloy.

The graphite-based material insertion layer includes iron (Fe), zirconium (Zr), gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), and bismuth (Bi). ), tin (Sn) or zinc (Zn) may further include one or more selected from the group consisting of.

The positive active material layer includes lithium cobalt oxide (hereinafter referred to as LCO), lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide (hereinafter referred to as NCA), nickel It may include one or more of lithium cobalt manganate (hereinafter referred to as NCM), lithium manganate, and lithium iron phosphate.

The positive active material layer is LiNi _x Co _y Al _z O ₂ (NCA) or LiNi _x Co _y Mn _z O ₂ (NCM) (where 0 <x <1, 0 <y <1, 0 <z <1 and x + y+z = 1) Note ㅇIt may include one or more.

The solid electrolyte layer is Li _3+x La ₃ M ₂ O ₁₂ (0≤x≤10), Li ₃ PO ₄ , Li _x Ti _y (PO ₄ ) ₃ (0<x<2, 0<y<3) , Li _x Al _y Ti _z (PO ₄ ) ₃ , 0<x<2, 0<y<1, 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 (O≤x≤1, O≤y≤1, 0≤a≤1, and 0≤b≤1), Li _x La _y TiO ₃ (0<x<2, 0<y<3), Li _x M _y P _z S _w (M = at least one of Ge, Si, Sn, 0<x<4, 0<y<1, 0<z <1, 0<w<5), Li _x N _y (0<x<4, 0<y<2), Li _x PO _y N _z (0<x<4, 0<y<5, 0<z) <4), Li _x Si _y S _z , 0<x<3,0<y<2, 0<z<4), Li _x P _y S _z , 0<x<3, 0<y<3, 0 <z<7), Li ₂ O, LiF, LiOH, Li ₂ CO ₃ , LiAlO ₂ , Li ₂ O-Al ₂ O ₃ -SiO ₂ -P ₂ O ₅ -TiO ₂ -GeO ₂ , Li _x La _y M _z O ₁₂ (M = one or more of Te, Nb, Zr, 1<x<5, 0<y<4, 0<z<4) of one or more solid electrolyte material.

The solid electrolyte layer may have a thickness of 10 μm or more and 250 μm or less.

The graphite-based material insertion layer may further include a binder.

The binder is polyvinylidene fluoride (PvDF), polyvinyl alcohol (PVA) or copolymer polyvinyl alcohol-polyacrylic acid (copolymers PVA-PAA), carboxymethyl cellulose (CMC), styrene butadiene rubber (styrene) -butadiene rubber, SBR), and the content of the binder may be 1 to 10% by weight based on the total weight of the graphite-based material insertion layer.

The lithium alloy may include at least one of a Li-Al alloy, a Li-Sn alloy, a Li-In alloy, a Li-Ag alloy, a Li-Au alloy, a Li-Zn alloy, a Li-Ge alloy, and a Li-Si alloy. have.

The secondary battery may be a lithium battery.

The positive electrode layer may further include a positive electrode current collector disposed on one surface of the positive electrode active material layer.

The graphite-based material insertion layer may have a thickness of 0.1 μm or more and 0.3 μm or less.

이상 1500

이하이며, 엑스선 회절법을 이용한 002회절선에 의해 측정되는 c축 방향의 육각망면 면간격 (Lc)이 500

이상 800

이하이며, 종횡비(aspect ratio)가 0.44이상 0.55이상인,이차 전지의 제조 방법을 제공할 수 있다.According to another aspect, disposing a solid electrolyte layer; treating the surface of the solid electrolyte layer by mechanical milling; oxidizing the solid electrolyte layer by contacting an oxidizing gas to the solid electrolyte layer; naturally drying the oxidized solid electrolyte layer; coating a graphite-based material insertion layer on one surface of the solid electrolyte layer; disposing a laminate in which a metal layer and a negative electrode current collector are bonded to one surface of the solid electrolyte layer; Disposing a positive electrode layer including a positive electrode active material on the other surface of the solid electrolyte layer; includes, wherein the crystallinity of the graphite material included in the graphite material insertion layer is measured by 110 diffraction lines using X-ray diffraction method The crystallite size (La) is 1000

more than 1500

Below, the interplanar spacing (Lc) of the hexagonal mesh in the c-axis direction measured by 002 diffraction ray using the X-ray diffraction method is 500

more than 800

or less, and an aspect ratio of 0.44 or more and 0.55 or more, it is possible to provide a method of manufacturing a secondary battery.

The graphite-based material insertion layer may be coated by ink coating or pencil drawing.

The disposing of the laminate in which the metal layer and the negative electrode current collector are bonded to one surface of the solid electrolyte layer may be performed by a cold isostatic press.

The positive active material layer includes lithium cobalt oxide (hereinafter referred to as LCO), lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide (hereinafter referred to as NCA), nickel It may include one or more of lithium cobalt manganate (hereinafter referred to as NCM), lithium manganate, and lithium iron phosphate.

The solid electrolyte layer is Li _3+x La ₃ M ₂ O ₁₂ (0≤x≤10), Li ₃ PO ₄ , Li _x Ti _y (PO ₄ ) ₃ (0<x<2, 0<y<3) , Li _x Al _y Ti _z (PO ₄ ) ₃ , 0<x<2, 0<y<1, 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 (O≤x≤1, O≤y≤1, 0≤a≤1, and 0≤b≤1), Li _x La _y TiO ₃ (0<x<2, 0<y<3), Li _x M _y P _z S _w (M = at least one of Ge, Si, Sn, 0<x<4, 0<y<1, 0<z <1, 0<w<5), Li _x N _y (0<x<4, 0<y<2), Li _x PO _y N _z (0<x<4, 0<y<5, 0<z) <4), Li _x Si _y S _z , 0<x<3,0<y<2, 0<z<4), Li _x P _y S _z , 0<x<3, 0<y<3, 0 <z<7), Li ₂ O, LiF, LiOH, Li ₂ CO ₃ , LiAlO ₂ , Li ₂ O-Al ₂ O ₃ -SiO ₂ -P ₂ O ₅ -TiO ₂ -GeO ₂ , Li _x La _y M _z O ₁₂ (M = one or more of Te, Nb, Zr, 1<x<5, 0<y<4, 0<z<4) of one or more solid electrolyte material.

The metal layer may include at least one of lithium or a lithium alloy.

The positive electrode layer may further include a positive electrode current collector disposed on one surface of the positive electrode active material layer.

The graphite-based material insertion layer includes iron (Fe), zirconium (Zr), gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), and bismuth (Bi). ), tin (Sn) or zinc (Zn) may further include one or more selected from the group consisting of.

The graphite-based material insertion layer may have a thickness of 0.1 μm or more and 0.3 μm or less.

The secondary battery according to an example may prevent a short circuit that may be caused by lithium (metal lithium) deposited on the negative electrode side during charging.

In addition, the secondary battery according to an example may have excellent charge/discharge characteristics.

In addition, the secondary battery according to an example may have advantageous characteristics in terms of process easiness and manufacturing cost.

1 is a schematic diagram showing a configuration of a secondary battery according to an embodiment.
FIG. 2 is a scanning electron microscope (SEM) photograph obtained by observing a cross-section of a secondary battery after overcharging the secondary battery according to an exemplary embodiment.
3A is a schematic diagram illustrating a configuration of a secondary battery before charging is performed in a secondary battery according to the related art.
3B is a schematic diagram illustrating a cross-section of a secondary battery after overcharging the secondary battery according to the related art.
3C is a scanning electron microscope (SEM) photograph obtained by observing a cross-section of a secondary battery after overcharging according to the related art;
4 is an X-ray diffraction data graph of a graphite-based material included in a graphite-based material insertion layer according to an exemplary embodiment.
5A is a scanning electron microscope (SEM) photograph of a graphite-based material insertion layer according to an exemplary embodiment.
FIG. 5B is an X-ray diffraction data graph of the first region shown in FIG. 5A .
FIG. 5C is an X-ray diffraction data graph of the second region shown in FIG. 5A .
FIG. 5D is an X-ray diffraction data graph of the third region shown in FIG. 5A .
6A to 6G are schematic diagrams schematically illustrating a method of manufacturing a secondary battery according to an exemplary embodiment.
7 is a graph showing the output characteristics of the secondary battery according to an embodiment and the secondary battery with respect to energy efficiency according to a charge/discharge cycle according to Comparative Example 1. Referring to FIG.
8 is a graph showing charge/discharge characteristics of a secondary battery according to an exemplary embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS Certain embodiments of the invention are shown in the drawings and are described in the detailed description. However, this is not intended to limit the concept of the present invention to specific embodiments, and all equivalents without departing from the spirit and technical scope of the present invention may be included in the concept of the present invention.

The terms used herein are used only to describe specific embodiments, and do not limit the present invention. Expressions used in the singular include the plural expression unless the context clearly has a different meaning. As used herein, terms such as "comprising" and "having" are intended to denote the presence of a feature, number, step, action, component, part, ingredient, material. As used herein, the symbol "/" may be interpreted as "and" or "or" depending on the context.

Throughout the specification, when a component, such as a layer, thin film, region, or plate, is referred to as being “on” another component, the component is placed in direct contact with the other component, or an intermediate component is interposed therebetween. may exist. However, when a component is referred to as being "on top" of another component, there is no intermediate component.

The terminology used herein is for the purpose of describing particular embodiments and is not intended to be limiting. For example, "an element" has the same meaning as "at least one element" unless the context dictates otherwise.

Also, relative terms such as “bottom” or “bottom” and “top” or “top” may be used in the present invention to describe the relationship of one component to another as illustrated in the drawings. It is understood that the relative terms are intended to encompass other orientations of the device in addition to the orientations depicted in the drawings. Accordingly, the exemplary term “lower” may include both directions of “lower” and “upper” depending on the particular orientation of the drawing.

As used herein, "about" or "approximately" includes the numerical values indicated, and means within an acceptable range of deviations from the particular value as determined by one of ordinary skill in the art in view of the measurement and error of the numerical value. For example, "about" can mean within one or more standard deviations, or within ±30%, 20%, 10%, or 5% of a specified value.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Also, terms such as terms defined in commonly used dictionaries should be construed as having meanings consistent with their meanings in the context of the related art and the present disclosure, and not as idealized terms.

As a method of using lithium as an anode active material, there are a method of using lithium or a lithium alloy as an anode active material layer and a method of not forming an anode active material layer on the anode current collector. In the latter case, a solid electrolyte layer is formed on the anode current collector and lithium, which is deposited at the interface between the anode current collector and the solid electrolyte by charging, is used as an active material. The negative electrode current collector is composed of a metal that does not form both an alloy and a compound with lithium. However, when lithium is used as an anode active material, lithium may form dendrites, which may lead to low energy efficiency of the secondary battery and/or short circuit of the secondary battery. Accordingly, there is a need for an improved electrode structure of a secondary battery.

Hereinafter, a secondary battery and a method of manufacturing the secondary battery according to embodiments will be described in detail with reference to the accompanying drawings. The width and thickness of the layers or regions shown in the accompanying drawings may be slightly exaggerated for clarity and convenience of description. Like reference numerals refer to like elements throughout the detailed description.

1 is a schematic diagram showing a configuration of a secondary battery according to an embodiment. FIG. 2 is a scanning electron microscope (SEM) photograph obtained by observing a cross-section of a secondary battery after overcharging the secondary battery according to an exemplary embodiment. 3A is a cross-sectional view illustrating a schematic configuration of a secondary battery before charging is performed in a secondary battery according to the related art. 3B is a cross-sectional view schematically illustrating a cross-section of a secondary battery according to the related art after overcharging the secondary battery. 3C is a scanning electron microscope (SEM) photograph obtained by observing a cross-section of the secondary battery after overcharging the secondary battery according to the related art. 4 is a graph of X-ray diffraction data of a diffraction angle (°2θ) with respect to a count of a graphite-based material included in a graphite-based material insertion layer according to an exemplary embodiment. 5A is a scanning electron microscope (SEM) photograph of a graphite-based material insertion layer according to an exemplary embodiment. FIG. 5B is an X-ray diffraction data graph of the first region shown in FIG. 5A . FIG. 5C is an X-ray diffraction data graph of the second region shown in FIG. 5A . FIG. 5C is an X-ray diffraction data graph of the third region shown in FIG. 5A .

1 and 2 , the secondary battery according to an example may include a positive electrode layer 10 , a negative electrode layer 20 , a graphite-based material insertion layer 30 , and a solid electrolyte layer 40 . The positive electrode layer 10 according to an example may include a positive electrode current collector 11 and a positive electrode active material layer 12 . The positive electrode current collector 11 is, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), It may include one or more of zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof. As an example, the positive electrode current collector 11 may be provided in the form of a plate-shaped thin film. According to another embodiment, the positive electrode current collector 11 may be omitted.

The positive active material layer 12 may include a positive active material and a solid electrolyte. In addition, the solid electrolyte included in the positive electrode layer 10 may be similar to or different from the solid electrolyte included in the solid electrolyte layer 40 . Details of the solid electrolyte included in the positive electrode active material layer 12 will be described later in more detail with respect to the solid electrolyte layer 40 .

The positive active material according to an example may reversibly occlude and discharge lithium ions. For example, the positive active material may be lithium cobalt oxide (hereinafter referred to as LCO), lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide (hereinafter referred to as NCA), or the like. , nickel cobalt lithium salts such as lithium manganate (hereinafter referred to as NCM), lithium manganate, lithium iron phosphate, nickel sulfide, copper sulfide, lithium sulfide sulfur, iron oxide, or vanadium oxide (vanadium oxide) may include one or more. As an example, the positive electrode active material may include the above-mentioned materials individually, or may include a compound in which two or more kinds are combined.

As an example, when the positive active material is formed of a lithium salt of a ternary transition metal oxide such as NCA or NCM and includes nickel (Ni) as the positive active material, the capacity density of the secondary battery 1 is increased to It is possible to reduce the metal elution of the positive electrode active material. Accordingly, the long-term reliability and cycle characteristics of the secondary battery 1 in a state of charge according to the present embodiment may be improved. As an example, the ternary transition metal oxide is LiNi _x Co _y Al _z O ₂ (NCA) or LiNi _x Co _y Mn _z O ₂ (NCM), where 0 <x <1, 0 <y <1, 0 <z <1 and x + y + z = 1), but the present disclosure is not limited thereto.

The shape of the particles included in the positive active material according to an example may be, for example, a sphere, an elliptical sphere, or the like. In addition, the diameter of the particles included in the positive electrode active material is not particularly limited, and may have a diameter in a range applicable to the positive electrode active material of a conventional solid secondary battery. In addition, the content of the positive electrode active material of the positive electrode layer 10 is also not particularly limited, and may be within a range applicable to the positive electrode layer of a conventional solid secondary battery.

The negative electrode layer 20 according to an example may include a negative electrode current collector 21 and a metal layer 22 . The negative electrode current collector 21 according to an example may include a material that does not react with lithium, that is, does not form both an alloy and a compound. For example, the negative electrode current collector 21 may include one or more of copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni). As an example, the negative electrode current collector 21 may include one of the aforementioned metals or an alloy including two or more of the aforementioned metals. The negative electrode current collector 21 according to an example may be implemented in a plate shape or a thin film shape.

The metal layer 22 according to an example may include lithium or a lithium alloy. That is, the metal layer 22 may function as a lithium reservoir. For example, lithium alloys are Li-Al alloys, Li-Sn alloys, Li-In alloys, Li-Ag alloys, Li-Au alloys, Li-Zn alloys, Li-Ge alloys, Li-Si alloys, Li-C It may be one or more of the alloys. For example, the metal layer 22 may include lithium or one of the above-described lithium alloys, or several kinds of lithium alloys.

In addition, the thickness of the metal layer 22 is, for example, about 1 μm or more and about 200 μm or less, for example, about 5 μm or more and about 190 μm or less, about 10 or more and about 180 μm or less, about 20 μm or more and about 170 μm or less, It may be about 40 μm or more and about 160 μm or less, about 80 μm or more and about 150 μm or less, or about 100 μm or more and about 140 μm or less. When the thickness of the metal layer 22 is less than 1 µm, there is a possibility that the reservoir function of the metal layer 22 cannot be sufficiently exhibited. When the thickness of the metal layer 22 exceeds 200 μm, the mass and volume of the secondary battery 1 increase, so that the capacity characteristics of the secondary battery 1 may be rather deteriorated. The metal layer 22 according to an example may be, for example, a metal foil having a thickness of about 1 μm or more and about 200 μm or less.

The graphite-based material insertion layer 30 according to an example may include a graphite-based material that forms an alloy or compound with lithium. As an example, lithium is occluded in the graphite-based material insertion layer 30 at the initial stage of charging of the secondary battery 1 . That is, the graphite-based material may form an alloy or compound with lithium ions that have migrated from the positive electrode layer 10 . When charging exceeds the capacity of the graphite-based material insertion layer 30, lithium is deposited on the back side of the graphite-based material insertion layer 30, that is, between the metal layer 22 and the graphite-based material insertion layer 30, The metal layer 23 is formed by lithium. The metal layer 23 may mainly include lithium (ie, metallic lithium or lithium alloy).

In addition, when the secondary battery 1 according to an example is discharged, lithium in the graphite-based material insertion layer 30 and the metal layer 23 is ionized and moves toward the positive electrode layer 10 . Therefore, in the secondary battery 1 according to an example, lithium may be used as an anode active material. In addition, since the graphite-based material insertion layer 30 covers the metal layer 23 , it serves as a protective layer for the metal layer 23 and at the same time prevents lithium from being deposited and growing into a dendrite structure. . Here, if the graphite-based material insertion layer 30 is not sufficiently crystallized, the graphite-based material insertion layer 30 may not sufficiently function as a protective layer.

As an example, when the graphite-based material insertion layer 30 is disposed on one surface of the solid electrolyte layer 40 in a non-planar shape as shown in FIG. 3A related to a conventional secondary battery, FIGS. 3B and 3C As shown, the graphite-based material insertion layer 30 may be changed to a _{metal oxide (LiC 6 ) combined with the metal layer 22 .} At this time, lithium generated in the charging process of the secondary battery may be precipitated in a dendrite structure, and short circuit and capacity decrease of the secondary battery 1 may occur due to lithium deposited in a dendrite structure. have.

이상, 예를 들어 약 1000

이상 약 1500

이하이며, 엑스선 회절법을 이용한 002회절선에 의해 측정되는 c축 방향의 육각망면 면간격(Lc)이 500

이상, 예를 들어 약 500

이상 약 800

이하이고, 종횡비(aspect ratio)가 0.44이상 0.55이하일 수 있다. The graphite-based material insertion layer 30 according to an example may include a graphite-based material having a predetermined crystallinity. For example, as shown in FIG. 4 , the graphite-based material included in the graphite-based material insertion layer 30 has a crystalline size (La) of the graphite-based material measured by 110 diffraction lines using X-ray diffraction. 1000

more than, for example, about 1000

more than about 1500

Below, the interplanar spacing (Lc) of the hexagonal mesh in the c-axis direction measured by 002 diffraction ray using the X-ray diffraction method is 500

more than, for example, about 500

more than about 800

or less, and an aspect ratio may be 0.44 or more and 0.55 or less.

이상임에 따라, 결정화를 위한 충분한 크기의 결정자를 구비할 수 있다. As an example, the size of the particles of the graphite-based material observed in the X-ray diffraction method is defined as the size of the crystal grains (Crystallite). The method of measuring the crystal size can estimate the size of the crystallites using the peak broadening of 110 diffraction lines of the X-ray diffraction data as shown in FIG. 4 . It can be quantitatively calculated using the Scherrer formula. As an example, the crystallite size (La) of the graphite-based material is 1000

According to the above, it is possible to have crystallites having a size sufficient for crystallization.

이상일 수 있다. In addition, the interplanar spacing (Lc) of the hexagonal mesh is an index indicating the graphitization degree of the graphite-based material particles. As an example, the interplanar spacing Lc of the hexagonal mesh may be calculated by the Bragg formula by obtaining the peak position of the graph of the 002 diffraction line of the X-ray diffraction data as shown in FIG. 4 by the integration method. As an example, as the interplanar spacing Lc of the hexagonal network decreases, crystals of the graphite-based material particles may develop. That is, the graphitization degree may be high. The hexagonal mesh plane spacing (Lc) of the graphite-based material according to an example is 500

may be more than

이상이며, 엑스선 회절법을 이용한 002회절선에 의해 측정되는 c축 방향의 육각망면 면간격(Lc)이 500

이상인 경우, 도 1에 도시된 바와 같이 흑연계 물질 삽입층(30)은 고체 전해질층(40)의 일면에 평면 형상으로 배치된다. 반면, 흑연계 물질 삽입층(30)에 포함되는 흑연계 물질의 결정질의 크기(La)가 1000

미만이며, 엑스선 회절법을 이용한 002회절선에 의해 측정되는 c축 방향의 육각망면 면간격(Lc)이 500

미만인 경우, 도 3a에 도시된 바와 같이 흑연계 물질 삽입층(30)은 고체 전해질층(40)의 일면에 평면 형상으로 배치되지 않는다.As described above, the crystalline size (La) of the graphite-based material included in the graphite-based material insertion layer 30 is 1000.

above, the interplanar spacing (Lc) of the hexagonal mesh in the c-axis direction measured by 002 diffraction ray using the X-ray diffraction method is 500

In this case, as shown in FIG. 1 , the graphite-based material insertion layer 30 is disposed on one surface of the solid electrolyte layer 40 in a planar shape. On the other hand, the crystalline size La of the graphite-based material included in the graphite-based material insertion layer 30 is 1000

less than, and the interplanar spacing (Lc) of the hexagonal mesh in the c-axis direction measured by 002 diffraction ray using X-ray diffraction method is 500

If less than, the graphite-based material insertion layer 30 is not disposed on one surface of the solid electrolyte layer 40 in a planar shape as shown in FIG. 3A .

According to an embodiment of the present invention, the average aspect ratio of the graphite-based material may be 0.44 or more and 0.55 or less. Here, the average aspect ratio of the graphite-based material is the c-axis measured by the 002 diffraction line using the X-ray diffraction method for the crystalline size (La) of the graphite-based material included in the graphite-based material insertion layer 30 . It means the ratio (Lc/La) of the interplanar spacing (Lc) of the hexagonal mesh planes in the direction. As an example, when the average aspect ratio of the graphite-based material is within the above range, the graphite-based material insertion layer 30 may be expanded in a more uniform direction.

The graphite-based material insertion layer 30 according to an example may additionally include other materials as well as a graphite-based material having a predetermined crystallinity. As an example, the graphite-based material insertion layer 30 may include iron (Fe), zirconium (Zr), gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver ( Ag), aluminum (Al), bismuth (Bi), tin (Sn), or zinc (Zn) may include at least one selected from the group consisting of. However, the present disclosure is not limited thereto, and the graphite-based material includes aluminum (Al), silicon (Si), titanium (Ti), zirconium (Zr), niobium (Nb), germanium (Ge), and gallium (Ga). , silver (Ag), indium (In), tin (Sn), antimony (Sb), and may include at least one selected from the group consisting of bismuth (Bi). When the graphite-based material insertion layer 30 includes the above-described mixed material, characteristics of the secondary battery 1 may be further improved.

In addition, the graphite-based material insertion layer 30 according to an example may include a binder. For example, the binder is polyvinylidene fluoride (PvDF), polyvinyl alcohol (PVA) or copolymer polyvinyl alcohol-polyacrylic acid (copolymers PVA-PAA), carboxymethyl cellulose (CMC), styrene butadiene rubber (styrene-butadiene rubber, SBR) may be included. As an example, when the graphite-based material insertion layer 30 includes a binder, the graphite-based material insertion layer 30 may be stably disposed on the solid electrolyte layer 40 . For example, when the graphite-based material insertion layer 30 does not include a binder, the graphite-based material insertion layer 30 may be easily separated from the solid electrolyte layer 40 . When a portion of the graphite-based material insertion layer 30 is separated from the solid electrolyte layer 40 , the solid electrolyte layer 40 may be exposed to the metal layer 23 , and thus a short circuit may occur. As an example, when the graphite-based material insertion layer 30 includes a binder, the content of the binder may be about 1 to 10 wt % based on the total weight of the graphite-based material insertion layer 30 . When the content of the binder is less than 1% by weight, the strength of the film is not sufficient, the properties are deteriorated, and it may be difficult to process/handle. When the content of the binder exceeds 5 wt %, the characteristics of the secondary battery 1 may be deteriorated.

The thickness of the graphite-based material insertion layer 30 may be, for example, 0.1 μm or more and 0.3 μm or less. When the thickness of the graphite-based material insertion layer 30 is less than 0.1 μm, there is a possibility that the characteristics of the secondary battery 1 may not be sufficiently improved. When the thickness of the graphite-based material insertion layer 30 exceeds 0.3 μm, the resistance value of the graphite-based material insertion layer 30 is high, and as a result, the characteristics of the secondary battery 1 may not be sufficiently improved. When the above-mentioned binder is used, the thickness of the graphite-based material insertion layer 30 capable of improving the characteristics of the secondary battery 1 can be easily secured at an appropriate level.

The solid electrolyte layer 40 according to an example may be disposed between the positive electrode layer 10 and the negative electrode layer 20 . As an example, the solid electrolyte layer 40 is Li _3+x La ₃ M ₂ O ₁₂ (0≤x≤10), Li ₃ PO ₄ , Li _x Ti _y (PO ₄ ) ₃ (0<x<2, 0<y<3), Li _x Al _y Ti _z (PO ₄ ) ₃ , 0<x<2, 0<y<1, 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 (O≤x≤1, O≤y≤1, 0≤a≤1, and 0≤b≤ 1), Li _x La _y TiO ₃ (0<x<2, 0<y<3), Li _x M _y P _z S _w (M = Ge, Si, Sn, 0<x<4, 0<y< 1, 0<z<1, 0<w<5), Li _x N _y (0<x<4, 0<y<2), Li _x PO _y N _z (0<x<4, 0<y< 5, 0<z<4), SiS ₂ (Li _x Si _y S _z , 0<x<3,0<y<2, 0<z<4), P ₂ S ₅ (Li _x P _y S _z , 0<x<3, 0<y<3, 0<z<7), Li ₂ O, LiF, LiOH, Li ₂ CO ₃ , LiAlO ₂ , Li ₂ O-Al ₂ O ₃ -SiO ₂ -P ₂ O ₅ -TiO ₂ -GeO ₂ , Li _x La _y M _z O ₁₂ (M = at least one of Te, Nb, Zr, 1<x<5, 0<y<4, 0<z<4), Li _x La _y Zr _z1 M _z2 O ₁₂ (M = B, at least one of Si,Al, Ga, Ge, Te,Nb,Hf,Ta,Ru,W,Re, 1<x<5, 0<y<4, 0 and solid electrolyte materials such as <z1<4, 0<z2<4).

As described above, the solid electrolyte layer 40 may include an ion conductive material to enable conduction of ions between the positive electrode layer 10 and the negative electrode layer 20, or an ion conductive material together with the ion conductive material. may be In addition, in this case, the solid electrolyte layer 40 may be used as a separator that physically or chemically separates the anode layer 10 and the cathode layer 20 . As an example, the thickness of the solid electrolyte layer 40 is about 10 µm or more and about 250 µm or less, for example, about 20 µm or more and about 225 µm or less, about 40 µm or more and about 200 µm or less, about 60 µm or more and about 175 µm or more. μm or less, about 80 μm or more and about 150 μm or less, or about 100 μm or more and about 125 μm or less. However, the present disclosure is not limited thereto.

In addition, the solid electrolyte layer 40 may further include a binder. The binder included in the solid electrolyte layer 40 may be, for example, one or more of styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, and polyethylene. . However, the present disclosure is not limited thereto, and the binder of the solid electrolyte layer 40 may be the same as or different from the binder of the positive electrode active material layer 12 or the graphite-based material insertion layer 30 .

6A to 6G are schematic diagrams schematically illustrating a method of manufacturing a secondary battery according to an exemplary embodiment.

Referring to FIG. 6A , the solid electrolyte layer 40 according to an embodiment is made of LLZO-based ceramics (Li _x La _y Zr _z O ₁₂ (1<x<5, 0<y<4, 0<z<4)) can be formed using As an example, a predetermined amount of starting materials (for example, lithium nitrate, lanthanum nitrate and zirconium oxychloride, etc.) are mixed, made into pellets, and then reacted at a predetermined reaction temperature in a vacuum state, LLZO-based solid electrolyte material can be prepared by rapid cooling. For example, when a mechanical milling method is used, the LLZO-based solid electrolyte material can be prepared by stirring and reacting starting materials (for example, lithium nitrate, lanthanum nitrate and zirconium oxychloride, etc.) using a ball mill or the like. . In addition, the stirring speed and stirring time of the mechanical milling method are not particularly limited, but the faster the stirring speed, the faster the production rate of the LLZO-based solid electrolyte material. can increase

As an example, when using the mechanical milling method, the starting material may be stirred in isopropyl alcohol (isopropyl alcohol) for a stirring speed of 200 rpm and a stirring time of 10 hours. After the stirred mixture is dried, a calcine process is performed at a temperature of about 1000° C. for 2 to 4 hours. After applying a pressure of 50 MPa to the calcined LLZO-based powder to form a pellet, the sintering process is performed at a temperature of about 1200° C. for 1 to 24 hours, and then quenched to prepare an LLZO-based solid electrolyte material. have.

Thereafter, the mixed raw material obtained by the melt quenching method or the mechanical milling method is heat-treated at a predetermined temperature, and then pulverized to prepare a particulate solid electrolyte. When a solid electrolyte has a glass transition characteristic, it may be changed from amorphous to crystalline by heat treatment.

Then, the solid electrolyte obtained by the above method is deposited using a known film formation method such as, for example, an aerosol deposition method, a cold spray method (at room temperature 20 °C), and a sputtering method, The solid electrolyte layer 40 can be manufactured. In addition, the solid electrolyte layer 40 may be manufactured by pressing a plurality of solid electrolyte particles. In addition, the solid electrolyte layer 40 may be applied by mixing a solid electrolyte, a solvent, and a binder, dried and pressurized to prepare the solid electrolyte layer 40 .

Referring to FIG. 6B , next, both surfaces of the solid electrolyte layer 40 may be mechanically polished to create a clean and flat surface. As an example, both surfaces of the solid electrolyte layer 40 may be mechanically polished using sand paper including silicon carbide (SiC) for about 30 seconds to about 2 minutes.

Referring to FIG. 6C , the solid electrolyte layer 40 may be dried after acid treatment. As an example, the solid electrolyte layer 40 may be acid-treated in a phosphoric acid solution (H ₃ PO ₄ ) for 5 minutes. Thereafter, ethanol may be applied to the solid electrolyte layer 40 and then naturally dried.

이며, c축 방향의 육각망면 면간격(Lc)이 607

일 수 있다. 예를 들어 일 실시예에 따른 흑연계 물질 삽입층(30)은 흑연계 물질(STAEDLER社의 HB 모델)로부터 입수할 수 있다. 일 예시에 따르면, 흑연계 물질 삽입층(30)은 드로잉(drawing) 방식으로 고체 전해질층(40)의 일면에 코팅되거나 잉크 코팅 방식을 이용하여 고체 전해질층(40)의 일면에 배치될 수 있다.Referring to FIG. 6D , next, the graphite-based material insertion layer 30 according to an embodiment is applied to one surface of the solid electrolyte layer 40 . According to one example, the graphite-based material included in the graphite-based material insertion layer 30 has a crystalline size (La) of 1095 of the graphite-based material.

, and the interplanar spacing (Lc) of the hexagonal mesh in the c-axis direction is 607.

can be For example, the graphite-based material insertion layer 30 according to an embodiment may be obtained from a graphite-based material (HB model manufactured by STAEDLER). According to one example, the graphite-based material insertion layer 30 may be coated on one surface of the solid electrolyte layer 40 by a drawing method or disposed on one surface of the solid electrolyte layer 40 by using an ink coating method. .

Referring to FIG. 6E , a laminate in which the negative electrode current collector 21 and the metal layer 22 are bonded is attached on the graphite-based material insertion layer 30 . According to one example, the metal layer 22 in the form of a metal foil is bonded to the negative electrode current collector 21 in the form of a thin plate including copper (Cu). In this case, the metal layer 22 may be a lithium foil or a lithium alloy foil. The laminate in which the negative electrode current collector 21 and the metal layer 22 are bonded is attached to the graphite-based material insertion layer 30 . As an example, the laminate in which the negative electrode current collector 21 and the metal layer 22 are bonded may be attached to the graphite-based material insertion layer 30 by a cold isostatic press process. At this time, the pressing process may be performed for 3 minutes at a pressure of 250 MP at 20 °C.

Referring to FIG. 6f , the positive electrode layer 10 may be attached to the other surface of the solid electrolyte layer 40 . According to one example, the material (positive electrode active material NCM-111, binder, etc.) constituting the positive electrode active material layer 12 is impregnated in an ionic electrolyte solution and manufactured. Next, the obtained active material is applied on the positive electrode current collector 11 and dried. Next, the anode layer 10 is produced by pressurizing the obtained laminate (for example, pressurization using hydrostatic pressure). You may abbreviate|omit a pressurization process. The positive electrode layer 10 is manufactured by compacting and molding a mixture of materials constituting the positive electrode active material layer 12 into a pellet form or extending (molding) it into a sheet form. When the positive electrode layer 10 is manufactured in this way, the positive electrode current collector 11 may be omitted. The generated positive electrode layer 10 may be attached to the other surface of the solid electrolyte layer 40 using a pressing process.

Referring to FIG. 6G, next, the negative electrode layer 20, the graphite-based material insertion layer 30, the solid electrolyte layer 40, and the positive electrode layer 10 are sealed in the laminating film 50 in a vacuum state, in one embodiment. It is possible to manufacture a secondary battery according to the. Here, each part of the positive electrode current collector 11 and the negative electrode current collector 21 may protrude out of the laminate film so as not to break the vacuum of the battery. These protrusions may be positive electrode layer terminals and negative electrode layer terminals.

7 is a graph showing output characteristics of a secondary battery according to an embodiment and a secondary battery according to Comparative Example 1. Referring to FIG. 8 is a graph showing charge/discharge characteristics of a secondary battery according to an exemplary embodiment. As shown in Figure 8. It can be seen that the areal capacity in cycle 1 and cycle 18 is maintained in cycle 1 and cycle 18.

The secondary battery 1 according to an embodiment is charged in excess of the charging capacity of the graphite-based material insertion layer 30 . That is, the graphite-based material insertion layer 30 is overcharged. At the initial stage of charging, lithium is occluded in the graphite-based material insertion layer 30 . When the charge exceeds the capacity of the graphite-based material insertion layer 30 , lithium is deposited in the metal layer 22 (or on the metal layer 22 ). During discharge, lithium in the graphite material insertion layer 30 and the metal layer 22 (or on the metal layer 22 ) is ionized and moves toward the positive electrode layer 10 . Accordingly, the secondary battery 1 may use lithium as an anode active material. In addition, since the graphite-based material insertion layer 30 covers the metal layer 22 , it can serve as a protective layer for the metal layer 22 and suppress the precipitation growth of dendrites. This can suppress a short circuit and a decrease in capacity of the secondary battery 1 , and further improve the characteristics of the secondary battery 1 .

(1. Example 1)

In Example 1, the secondary battery according to Example 1 may be manufactured by the process with reference to FIGS. 6A to 6G.

(2. Comparative Example 1)

In Comparative Example 1, the graphite-based material insertion layer 30 is a graphite-based material, and includes a bare graphite material. The crystallite size (La) of the bare graphite material and the interplanar spacing (Lc) of the hexagonal mesh in the c-axis direction are not measured. A secondary battery was manufactured and tested in the same manner as in Example 1, except that the graphite-based material insertion layer 30 including the above-described graphite-based material was used.

(3. Charge/discharge test)

The charge/discharge characteristics of the secondary batteries of Example 1 and Comparative Example 1 as described above were evaluated by the following charge/discharge tests. The charge/discharge test was performed by putting the secondary battery in a constant temperature bath at 60°C. The first cycle to the sixth cycle were ^{charged with a constant current of 0.5 mA/cm 2} until the battery voltage reached 4.2V, and constant voltage charging of 4.2V was performed. Then, discharge was performed with a constant current of ^{0.5 mA/cm 2} until the secondary battery voltage reached 2.8 V. In the 7th cycle to the 11th cycle, it ^{was charged with a constant current of 1.0 mA/cm 2} until the battery voltage became 4.2V, and constant voltage charging of 4.2V was performed. Then, discharge was performed with a constant current of ^{1.0 mA/cm 2} until the secondary battery voltage reached 2.8 V. In the 12th cycle to the 16th cycle, it ^{was charged with a constant current of 1.6 mA/cm 2} until the battery voltage reached 4.2V, and constant voltage charging of 4.2V was performed. Then, discharge was performed with a constant current of ^{1.6 mA/cm 2} until the secondary battery voltage reached 2.8 V. The 17th to 18th cycles were ^{charged with a constant current of 2.0 mA/cm 2} until the battery voltage reached 4.2V, and constant voltage charging of 4.2V was performed.

7 and 8, in the case of Example 1, stable charging and discharging was possible for 18 cycles or more, and it can be confirmed that the energy efficiency is also superior to that of Comparative Example 1.

Although many matters have been specifically described in the above description, they should be construed as examples of specific embodiments rather than limiting the scope of the invention. For example, those skilled in the art will appreciate that the secondary battery and the method of manufacturing the secondary battery described with reference to the drawings may be variously changed. As a specific example, it can be seen that an all-solid secondary battery other than a secondary battery can be configured, a secondary battery using a partially liquid electrolyte can be configured, and the spirit and principle of the present application can be applied to other batteries other than lithium batteries. There will be. Therefore, the scope of the invention should not be determined by the described embodiments, but should be determined by the technical idea described in the claims.

1: secondary battery
10: anode layer
11: positive current collector
12: positive electrode active material layer
20: cathode layer
21: negative electrode current collector
22: metal layer
23: metal layer
30: graphite-based material insertion layer
40: solid electrolyte layer

Claims (22)

a positive electrode layer including a positive electrode active material layer;
a negative electrode layer comprising a negative electrode current collector and a metal layer disposed on the negative electrode current collector; and
a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer; and
Includes; a graphite-based interlayer disposed between the solid electrolyte layer and the negative electrode layer;
The graphite-based material insertion layer includes a graphite-based material,
The crystallinity of the graphite-based material included in the graphite-based material is,
The crystallite size (La) measured by 110 diffraction rays using X-ray diffraction is 1000

more than 1500

is below,
Hexagonal plane spacing (Lc) in the c-axis direction measured by 002 diffraction ray using X-ray diffraction method is 500

more than 800

is below,
An aspect ratio of 0.44 or more and 0.55 or more,
secondary battery. 2. The method of claim 1
The metal layer comprises at least one of lithium or a lithium alloy,
secondary battery. According to claim 1,
The graphite-based material insertion layer includes iron (Fe), zirconium (Zr), gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), and bismuth (Bi). ), tin (Sn) or zinc (Zn) further comprising at least one selected from the group consisting of
secondary battery. The method of claim 1,
The positive active material layer includes lithium cobalt oxide (hereinafter referred to as LCO), lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide (hereinafter referred to as NCA), nickel Lithium cobalt manganate (hereinafter referred to as NCM), lithium manganate, lithium iron phosphate containing at least one
secondary battery. 5. The method of claim 4,
The positive active material layer is LiNi _x Co _y Al _z O ₂ (NCA) or LiNi _x Co _y Mn _z O ₂ (NCM) (where 0 <x <1, 0 <y <1, 0 <z <1 and x + y+z = 1) Note ㅇIncluding one or more
secondary battery. 2. The method of claim 1
The solid electrolyte layer is Li _3+x La ₃ M ₂ O ₁₂ (0≤x≤10), Li ₃ PO ₄ , Li _x Ti _y (PO ₄ ) ₃ (0<x<2, 0<y<3) , Li _x Al _y Ti _z (PO ₄ ) ₃ , 0<x<2, 0<y<1, 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 (O≤x≤1, O≤y≤1, 0≤a≤1, and 0≤b≤1), Li _x La _y TiO ₃ (0<x<2, 0<y<3), Li _x M _y P _z S _w (M = at least one of Ge, Si, Sn, 0<x<4, 0<y<1, 0<z <1, 0<w<5), Li _x N _y (0<x<4, 0<y<2), Li _x PO _y N _z (0<x<4, 0<y<5, 0<z) <4), Li _x Si _y S _z , 0<x<3,0<y<2, 0<z<4), Li _x P _y S _z , 0<x<3, 0<y<3, 0 <z<7), Li ₂ O, LiF, LiOH, Li ₂ CO ₃ , LiAlO ₂ , Li ₂ O-Al ₂ O ₃ -SiO ₂ -P ₂ O ₅ -TiO ₂ -GeO ₂ , Li _x La _y M _z O ₁₂ (M = one or more of Te, Nb, Zr, 1<x<5, 0<y<4, 0<z<4) comprising a solid electrolyte material of at least one
secondary battery. 2. The method of claim 1
The solid electrolyte layer has a thickness of 10 μm or more and 250 μm or less,
secondary battery. The method of claim 1,
The graphite-based material insertion layer further comprises a binder (binder)
secondary battery. 9. The method of claim 8,
The binder is polyvinylidene fluoride (PvDF), polyvinyl alcohol (PVA) or copolymer polyvinyl alcohol-polyacrylic acid (copolymers PVA-PAA), carboxymethyl cellulose (CMC), styrene butadiene rubber (styrene) -butadiene rubber, SBR), and the content of the binder is 1 to 10% by weight based on the total weight of the graphite-based material insertion layer.
secondary battery. According to claim 1,
The lithium alloy comprises at least one of a Li-Al alloy, a Li-Sn alloy, a Li-In alloy, a Li-Ag alloy, a Li-Au alloy, a Li-Zn alloy, a Li-Ge alloy, a Li-Si alloy,
secondary battery. The method of claim 1,
The secondary battery is a lithium battery
secondary battery. The method of claim 1,
The positive electrode layer further comprises a positive electrode current collector disposed on one surface of the positive electrode active material layer,
secondary battery. The method of claim 1,
The graphite-based material insertion layer having a thickness of 0.1 μm or more and 0.3 μm or less
secondary battery.
disposing a solid electrolyte layer;
treating the surface of the solid electrolyte layer by mechanical milling;
oxidizing the solid electrolyte layer by contacting an oxidizing gas to the solid electrolyte layer;
naturally drying the oxidized solid electrolyte layer;
coating a graphite-based material insertion layer on one surface of the solid electrolyte layer;
disposing a laminate in which a metal layer and a negative electrode current collector are bonded to one surface of the solid electrolyte layer;
disposing a positive electrode layer including a positive electrode active material on the other surface of the solid electrolyte layer;
The crystallinity of the graphite-based material included in the graphite-based material insertion layer is
The crystallite size (La) measured by 110 diffraction rays using X-ray diffraction is 1000

more than 1500

is below,
Hexagonal plane spacing (Lc) in the c-axis direction measured by 002 diffraction ray using X-ray diffraction method is 500

more than 800

is below,
An aspect ratio of 0.44 or more and 0.55 or more,
A method for manufacturing a secondary battery. 15. The method of claim 14,
The coating of the graphite-based material insertion layer is made by ink coating or pencil drawing.
A method for manufacturing a secondary battery. 15. The method of claim 14,
The step of disposing the laminate in which the metal layer and the negative electrode current collector are bonded to one surface of the solid electrolyte layer is performed by a cold isostatic press.
A method for manufacturing a secondary battery. 15. The method of claim 14,
The positive active material layer includes lithium cobalt oxide (hereinafter referred to as LCO), lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide (hereinafter referred to as NCA), nickel Lithium cobalt manganate (hereinafter referred to as NCM), lithium manganate, lithium iron phosphate containing at least one
A method for manufacturing a secondary battery. 15. The method of claim 14,
The solid electrolyte layer is Li _3+x La ₃ M ₂ O ₁₂ (0≤x≤10), Li ₃ PO ₄ , Li _x Ti _y (PO ₄ ) ₃ (0<x<2, 0<y<3) , Li _x Al _y Ti _z (PO ₄ ) ₃ , 0<x<2, 0<y<1, 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 (O≤x≤1, O≤y≤1, 0≤a≤1, and 0≤b≤1), Li _x La _y TiO ₃ (0<x<2, 0<y<3), Li _x M _y P _z S _w (M = at least one of Ge, Si, Sn, 0<x<4, 0<y<1, 0<z <1, 0<w<5), Li _x N _y (0<x<4, 0<y<2), Li _x PO _y N _z (0<x<4, 0<y<5, 0<z) <4), Li _x Si _y S _z , 0<x<3,0<y<2, 0<z<4), Li _x P _y S _z , 0<x<3, 0<y<3, 0 <z<7), Li ₂ O, LiF, LiOH, Li ₂ CO ₃ , LiAlO ₂ , Li ₂ O-Al ₂ O ₃ -SiO ₂ -P ₂ O ₅ -TiO ₂ -GeO ₂ , Li _x La _y M _z O ₁₂ (M = one or more of Te, Nb, Zr, 1<x<5, 0<y<4, 0<z<4) comprising a solid electrolyte material
A method for manufacturing a secondary battery. 15. The method of claim 14,
The metal layer comprises at least one of lithium or a lithium alloy,
A method for manufacturing a secondary battery. 15. The method of claim 14,
The positive electrode layer further comprises a positive electrode current collector disposed on one surface of the positive electrode active material layer,
A method for manufacturing a secondary battery. 15. The method of claim 14,
The graphite-based material insertion layer includes iron (Fe), zirconium (Zr), gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), and bismuth (Bi). ), tin (Sn) or zinc (Zn) further comprising at least one selected from the group consisting of
A method for manufacturing a secondary battery. 15. The method of claim 14,
The graphite-based material insertion layer having a thickness of 0.1 μm or more and 0.3 μm or less
A method for manufacturing a secondary battery.

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