Anode for all-solid-state battery, method of manufacturing same, and all-solid-state battery including same

Abstract

Embodiments of an anode for an all-solid-state battery, the anode including an anode current collector and an anode active material layer disposed on the anode current collector and including an anode active material, the anode active material including a plate-type carbon material and a coating layer coated on a portion of a surface of the plate-type carbon material, wherein the length ratio (a / c) of the long axis (a) to the thickness (c) of the plate-type carbon material is 4 or more, and wherein the coating layer comprises a lithium-philic material.

Description

Technical Field

[0001] The present invention relates to an anode for an all-solid-state battery, a method for manufacturing the anode, and an all-solid-state battery comprising the anode. Background Art

[0002] Lithium secondary batteries are widely used in small devices to large energy storage systems, and the secondary battery market is booming due to the explosive growth of the electric vehicle market. In order to use lithium secondary batteries as an output source for electric vehicles, lithium secondary batteries need high energy density and good output characteristics, and special attention is paid to ensuring stability.

[0003] Conventional lithium secondary batteries for electric vehicles have the risk of fire and explosion due to liquid electrolytes containing flammable organic solvents, and they have low energy density due to the large volume occupied by one battery due to the application of a battery management system (BMS) for safely operating the lithium secondary batteries in a battery pack or battery module.

[0004] To solve the above problems, the next generation of all-solid-state batteries are being developed. All-solid-state batteries use non-flammable solid electrolytes to eliminate the risk of fire and explosion and ensure safety, so the fire safety-related parts of the battery management system can be omitted, so batteries with high energy density can be developed.

[0005] Currently, research is being actively conducted to develop graphite-silicon composite materials that have a higher capacity than graphite (372 mAh / g) as anode active materials for all-solid-state batteries. Since general blending methods are difficult to commercialize due to cracks and delamination caused by the large volume expansion of silicon (Si), a method of coating the surface of graphite with silicon (Si) to develop a high-capacity anode active material having a theoretical capacity of 2 to 3 times that of graphite has attracted attention.

[0006] However, when a general spherical carbon material is coated with silicon (Si) to ensure a high capacity of 1000 mAh / g or more, the lifespan characteristics of an all-solid-state battery including the obtained anode active material may be deteriorated.

[0007] The above information disclosed in this Background section is only for enhancement of understanding of the background technology of the embodiments of the present disclosure and therefore it may contain information that does not constitute the prior art that is already known to a person of ordinary skill in the art. Summary of the invention

[0008] The present disclosure relates to an anode for an all-solid-state battery, a method for manufacturing the anode, and an all-solid-state battery including the anode. In a specific embodiment, the anode has improved life characteristics and discharge capacity characteristics by including an anode active material configured such that the length ratio of its major axis to its minor axis is controlled within a specified range and a coating layer formed on the surface of the plate-shaped carbon material.

[0009] The embodiments of the present disclosure can solve the problems of the prior art, and the embodiments of the present disclosure reduce the degradation of the life characteristics and volume expansion rate of the all-solid-state battery by coating the surface of a plate-type carbon material as a substrate with a lithium-philic material, such as silicon (Si), rather than a traditional spherical carbon material.

[0010] One embodiment of the present disclosure provides an anode for an all-solid-state battery, comprising an anode current collector and an anode active material layer located on the anode current collector and comprising an anode active material, wherein the anode active material comprises a plate-type carbon material and a coating configured to coat at least a portion of a surface of the plate-type carbon material, wherein a length ratio (a / c) of a major axis (a) to a thickness (c) of the plate-type carbon material is greater than 4, and wherein the coating comprises a lithium-philic material.

[0011] In a preferred embodiment, the plate-type carbon material may include a material selected from natural graphite, artificial graphite, and a combination thereof.

[0012] In another preferred embodiment, the length ratio (a / c) of the major axis (a) to the thickness (c) of the plate-type carbon material may be 4.130 to 5.987.

[0013] In another preferred embodiment, the length ratio (a / b) of the major axis (a) to the minor axis (b) of the plate-type carbon material may be 1.120 to 2.054.

[0014] In another preferred embodiment, the average orientation angle of the major axis (a) of the plate-type carbon material relative to the plane direction of the anode current collector may be 12° or less.

[0015] In another preferred embodiment, the lithium-philic material may include a material selected from silicon (Si), silver (Ag), magnesium (Mg), tin (Sn), bismuth (Bi), zinc (Zn), and combinations thereof. Preferably, the lithium-philic material may include amorphous silicon (Si).

[0016] In a further preferred embodiment, the coating layer may have a thickness of 20 nm to 200 nm.

[0017] In another further preferred embodiment, the anode active material may include 10 wt % to 60 wt % of the coating layer relative to the total weight of the anode active material.

[0018] In another preferred embodiment, the anode active material layer may further include an inorganic electrolyte.

[0019] Another embodiment of the present disclosure provides an all-solid-state battery comprising an anode, a solid electrolyte layer located on the anode active material layer and comprising a solid electrolyte, a cathode active material layer located on the solid electrolyte layer and comprising a cathode active material, and a cathode current collector located on the cathode active material layer.

[0020] In a preferred embodiment, the all-solid-state battery may satisfy the following equation.

[0021] equation:

[0022] (V 100 -V 0 ) / V 0 ×100≤12%

[0023] Here, V 100 is the volume of the anode active material layer of the all-solid-state battery in a fully discharged state after 100 charge and discharge cycles, and V 0 It is the volume of the anode active material layer of the all-solid-state battery when it is not being charged or discharged.

[0024] Another embodiment of the present invention provides a method for manufacturing an anode for an all-solid-state battery, the method comprising preparing precursors of a plate-type carbon material and a lithium-philic material, synthesizing an anode active material comprising a plate-type carbon material and a coating configured to coat at least a portion of a surface of the plate-type carbon material, and stacking an anode active material layer comprising the anode active material on an anode current collector, wherein a length ratio (a / c) of a major axis (a) to a thickness (c) of the plate-type carbon material is greater than 4, and wherein the coating comprises a lithium-philic material from the precursor.

[0025] In a preferred embodiment, the length ratio (a / c) of the major axis (a) to the thickness (c) of the plate-type carbon material may be 4.130 to 5.987.

[0026] In another preferred embodiment, the average orientation angle of the major axis (a) of the plate-type carbon material relative to the plane direction of the anode current collector may be 12° or less.

[0027] In yet another preferred embodiment, the coating can be prepared using chemical vapor deposition.

[0028] In another preferred embodiment, the precursor may include a compound selected from SiH 4 、Si 2 H 6 、Si 3 H8 、SiCl 4 、SiHCl 3 、Si 2 Cl 6 、SiH 2 Cl 2 、SiH 3 Cl, and combinations thereof.

[0029] In another preferred embodiment, the coating layer may have a thickness of 20 nm to 200 nm.

[0030] In a further preferred embodiment, the anode active material layer may further include an inorganic electrolyte. Here, the weight ratio of the anode active material to the inorganic electrolyte included in the anode active material layer may be 1:0.5 to 1:1.

[0031] Other aspects and preferred embodiments of the present disclosure are discussed below.

[0032] The above and other features of embodiments of the present disclosure are discussed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The above and other features of the embodiments of the present disclosure will now be described in detail with reference to certain exemplary embodiments of the present disclosure shown in the accompanying drawings, which are given hereinafter by way of illustration only and therefore do not limit the embodiments of the present disclosure, and in which:

[0034] Figure 1 A cross-sectional view showing an all-solid-state battery according to an embodiment of the present disclosure.

[0035] Figure 2 A schematic perspective view showing a plate-type carbon material in an anode active material according to an embodiment of the present disclosure.

[0036] Figure 3 A schematic cross-sectional view showing an anode active material according to an embodiment of the present disclosure.

[0037] Figure 4 A cross-sectional view illustrating an anode active material layer including an anode active material according to an embodiment of the present disclosure.

[0038] Figure 5 A plan view showing an anode active material layer including an anode active material and an inorganic electrolyte according to an embodiment of the present disclosure.

[0039] FIG. 6A to FIG. 6D Scanning electron microscope (SEM) images of different positions of the side surface of the plate-type carbon material used in the synthesis of the anode active material according to Manufacturing Example 1 are shown.

[0040] 7A to 7DSEM images of different positions of the front surface of the plate-type carbon material used in the synthesis process of the anode active material according to Manufacturing Example 1 are shown.

[0041] FIG. 8A to FIG. 8D SEM images of various locations of the spherical carbon material used in the synthesis process of the anode active material according to Comparative Manufacturing Example 1 are shown.

[0042] Fig.9A and 9B SEM images of a cross section of the all-solid-state battery according to Example 1 taken at different magnifications are shown.

[0043] Fig. 10A and Fig. 10B SEM images of a cross section of the all-solid-state battery according to Comparative Example 1 taken at different magnifications are shown.

[0044] Fig.11A and Fig. 11B SEM images of a cross section of the all-solid-state battery according to Comparative Example 2 taken at different magnifications are shown.

[0045] Fig.12 A diagram showing the orientation angle of the long axis of the plate-type carbon material included in the all-solid-state batteries according to Example 1 and Comparative Example 2 with respect to the anode current collector.

[0046] Fig.13 A SEM image showing a cross section of the all-solid-state battery according to Example 1 in a fully discharged state after 100 charge and discharge cycles;

[0047] Fig.14 The SEM image of the cross section of the all-solid-state battery according to Comparative Example 1 in a fully discharged state after 100 charge and discharge cycles is shown.

[0048] Fig.15 A graph showing evaluation results of battery characteristics of all-solid-state batteries according to Example 1 and Comparative Example 1 when the formation process was performed at a rate of 0.1C.

[0049] Fig.16 A graph showing evaluation results of battery characteristics of the all-solid-state batteries according to Example 1 and Comparative Example 1 when the all-solid-state batteries are charged and discharged at a rate of 0.3C after a formation process; and

[0050] Fig.17 A graph showing evaluation results of the capacity retention rate of the all-solid-state batteries according to Example 1 and Comparative Example 1 when subjected to 100 charge and discharge cycles.

[0051] It should be understood that the accompanying drawings are not necessarily drawn to scale, but rather present a somewhat simplified representation of various preferred features that illustrate the basic principles of the embodiments of the present disclosure. The specific design features of the embodiments of the present disclosure disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes, will be determined in part by the specific intended application and use environment.

[0052] In the drawings, reference numbers refer to the same or equivalent parts of embodiments of the present disclosure throughout the several views. DETAILED DESCRIPTION

[0053] The above-mentioned purpose, other purposes, advantages and features of the embodiments of the present disclosure will become apparent from the description of the embodiments given below with reference to the accompanying drawings. However, the embodiments of the present disclosure are not limited to the embodiments disclosed herein and can be implemented in various different forms. These embodiments are provided to make the description of the embodiments of the present disclosure more thorough and to fully convey the scope of the embodiments of the present disclosure to those skilled in the art.

[0054] In the accompanying drawings, the same or similar elements are represented by the same reference numerals even if they are depicted in different drawings. In the accompanying drawings, for clarity of description, the size of the structure may be exaggerated compared to its actual size. In the following description of the embodiment, terms such as "first" and "second" can be used to describe various elements, but these elements are not limited. These terms are only used to distinguish one element from other elements. For example, without departing from the scope and spirit of the embodiments of the present disclosure, the first element can be named as the second element, and similarly, the second element can be named as the first element. Singular expressions can cover plural expressions unless they have significantly different contextual meanings.

[0055] In the following description of the embodiments, terms such as "include", "comprising" and "having" should be interpreted as indicating the presence of the features, numbers, steps, operations, elements, parts, or combinations thereof stated in this specification, and they do not exclude the presence of one or more other features, numbers, steps, operations, elements, parts, or combinations thereof, or the possibility of adding them. In addition, it should be understood that when a component, such as a layer, film, region, or plate, is referred to as being "on" another component, the component may be "directly" "on" the other component, or other components may be inserted between the two components. In the same way, it should be understood that when a component, such as a layer, film, region, or plate, is referred to as being "under" another component, the component may be "directly" "under" the other component, or other components may be inserted between the two components.

[0056] All numbers, values ​​and / or expressions used in this specification that represent component amounts, reaction conditions, polymer compositions and blends are approximate values, which reflect the various uncertainties in the measurements that arise when these values ​​are obtained from essentially different things, and therefore, it should be understood that, unless otherwise stated, they are modified by the term "about". In addition, it should be understood that, unless otherwise stated, if a numerical range is disclosed in this specification, the range includes all continuous values ​​from the minimum value to the maximum value of the range. In addition, unless otherwise stated, if such a range refers to an integer, the range includes all integers from the minimum integer to the maximum integer.

[0057] In the description of the following embodiments, it should be understood that when the range of a variable is specified, the variable includes all values ​​within the specified range, including the endpoints of the specified range. For example, it should be understood that the range of "5 to 10" includes not only the values ​​of 5, 6, 7, 8, 9 and 10, but also any sub-ranges, such as the sub-range of 6 to 10, the sub-range of 7 to 10, the sub-range of 6 to 9, the sub-range of 7 to 9, and any values ​​between the valid integers within the range of the range, such as 5.5, 6.5, 7.5, 5.5 to 8.5 and 6.5 to 9. In addition, for example, it should be understood that the range of "10% to 30%" includes not only all integers containing the values ​​of 10%, 11%, 12%, 13%, ... 30%, but also any sub-ranges, such as the sub-range of 10% to 15%, the sub-range of 12% to 18%, the sub-range of 20% to 30%, and any values ​​between the valid integers within the range of the range, such as 10.5%, 15.5% and 25.5%.

[0058] Anode for all-solid-state battery and all-solid-state battery containing the anode

[0059] Figure 1 An all-solid-state battery including an anode according to an embodiment of the present disclosure is shown. Figure 1 The all-solid-state battery may include an anode current collector 100, an anode active material layer 200 located on the anode current collector 100 and including an anode active material 210, a solid electrolyte layer 300 located on the anode active material layer 200 and including a solid electrolyte, a cathode active material layer 400 located on the solid electrolyte layer 300 and including a cathode active material, and a cathode current collector 500 located on the cathode active material layer 400.

[0060] An anode according to one embodiment of the present disclosure may include an anode current collector 100 and an anode active material layer 200 located on the anode current collector 100 and including an anode active material 210 , and the anode active material 210 may include a plate-type carbon material 211 and a coating layer 212 configured to coat at least a portion of a surface of the plate-type carbon material 211 .

[0061] The anode current collector 100 may be a plate-type substrate having conductivity. Specifically, the anode current collector 100 may be provided in the form of a sheet, a film, or a foil.

[0062] The anode current collector 100 may include a material that does not react with lithium. Specifically, the anode current collector 100 may include a material selected from nickel (Ni), copper (Cu), stainless steel (SUS), and a combination thereof. The thickness of the anode current collector 100 may be, for example, 1 μm to 500 μm, but is not limited to a specific value.

[0063] Figure 2 2 is a schematic perspective view of a plate-shaped carbon material 211. Figure 2 , the particle of the plate-type carbon material 211 may include a plate shape having an arbitrary major axis a, minor axis b, and thickness c. Here, the major axis a and the minor axis b may refer to axes included in a direction parallel to the wide surface of the particle of the plate-type carbon material 211. Specifically, of the two axes included in the wide surface of the particle of the plate-type carbon material 211 and perpendicular to each other, the major axis may be referred to as the major axis a, and the minor axis may be referred to as the minor axis b.

[0064] Figure 3 is a schematic cross-sectional view of an anode active material 210 according to an embodiment of the present disclosure. Figure 4 is a cross-sectional view of an anode active material layer 200 including an anode active material 210 according to an embodiment of the present disclosure.

[0065] Reference Figure 3 , the anode active material 210 may include a plate-type carbon material 211 and a coating layer 212 configured to coat at least a portion of a surface of the plate-type carbon material 211, and the coating layer 212 may include a lithium-philic material.

[0066] The conventional anode active material including the spherical carbon material and the coating layer configured to coat at least a portion of the surface of the spherical carbon material may be deformed due to pressure applied during the assembly process of the all-solid-state battery using the anode active material, or pressure generated due to volume expansion of the coating layer 212 in various directions during the charge and discharge process. Here, due to local volume expansion and contraction during the charge and discharge process, voids are formed between the deformed conventional anode active material particles, the interface resistance increases, and thus, the electrochemical characteristics of the all-solid-state battery may be deteriorated.

[0067] The anode active material 210 according to the embodiment of the present disclosure includes a plate-type carbon material 211 and can distribute the pressure applied to the anode active material 210 in a direction parallel to the plane of the plate-type carbon material 211 so as to minimize such deformation. Therefore, the all-solid-state battery including the anode active material 210 according to the embodiment of the present disclosure suppresses local volume expansion and contraction during charge and discharge, thereby improving the life characteristics of the all-solid-state battery and minimizing the irreversible capacity drop of the all-solid-state battery during the initial charge and discharge process.

[0068] In particular, refer to Figure 4 , the anode active material 210 exists in the anode active material layer 200 in a state where particles of the plate-type carbon material 211 are stacked along the vertical direction VD. Here, the amount of the lithium-philic material per unit length included in the anode active material layer 200 along the vertical direction VD may be greater than the amount of the lithium-philic material per unit length included in the anode active material layer 200 along the horizontal direction HD.

[0069] Thus, while the volume of conventional spherical carbon materials expands in various directions during charge and discharge, the volume expansion of the plate-type carbon material 211 is concentrated in the vertical direction VD, and thus, the formation of voids in the anode active material layer 200 can be suppressed, and the contact between the anode active material 210 and the solid electrolyte or inorganic electrolyte 220 to be described below can be improved.

[0070] In one embodiment, the length ratio (a / c) of the major axis a to the thickness c of the plate-shaped carbon material 211 may be greater than 4. Preferably, the length ratio (a / c) of the major axis a to the thickness c of the plate-shaped carbon material 211 may be 4.130 to 5.987, or more generally 4 to 6.

[0071] When the length ratio (a / c) of the major axis a to the thickness c of the plate-type carbon material 211 is less than 4.130, it may be difficult to achieve suppression of local volume expansion and contraction using the plate-type carbon material 211 according to an embodiment of the present disclosure. In addition, when the length ratio (a / c) of the major axis a to the thickness c of the plate-type carbon material 211 exceeds 5.987, the plate-type carbon material 211 is too thin and thus may be damaged due to pressure during charging and discharging, so that the electrochemical characteristics of the all-solid-state battery may be reduced.

[0072] In addition, the length ratio (a / b) of the major axis a to the minor axis b of the plate-type carbon material 211 may be 1.120 to 2.054 (about 1 to about 2). When the length ratio (a / b) of the major axis a to the minor axis b of the plate-type carbon material 211 exceeds 2.054, the length of the minor axis b and the thickness c are too short compared to the length of the major axis a, and thus, a needle-type carbon material is formed instead of the plate-type carbon material 211. In this case, it may be difficult to achieve the purpose of the embodiment of the present disclosure, that is, the volume expansion is concentrated in the vertical direction during charge and discharge.

[0073] In one embodiment, the plate-type carbon material 211 may include a material selected from natural graphite, artificial graphite, and combinations thereof.

[0074] In one embodiment, the average orientation angle of the major axis a of the plate-shaped carbon material 211 relative to the plane direction of the anode current collector 100 may be 12° or less. The lower limit of the average orientation angle may be, for example, 0° or more, without being limited to a specific value.

[0075] Here, the plane direction of the anode current collector 100 may refer to the horizontal direction of the anode current collector 100, such as Figure 1 When the average orientation angle between the major axis a of the plate-shaped carbon material 211 and the plane direction of the anode current collector 100 exceeds 12°, it may be difficult to achieve the purpose of the embodiment of the present disclosure, that is, since the volume expansion during charge and discharge is concentrated in the vertical direction, the life characteristics and electrochemical characteristics of the all-solid-state battery are improved.

[0076] In one embodiment, the lithium-philic material may include a material selected from silicon (Si), silver (Ag), magnesium (Mg), tin (Sn), bismuth (Bi), zinc (Zn), and combinations thereof. Preferably, the lithium-philic material may include amorphous silicon (Si). The lithium-philic material may refer to a material that can form an alloy with lithium (Li).

[0077] When a typical all-solid-state battery is charged, lithium-ion (Li + ) is released from the cathode active material and reaches the anode active material via the solid electrolyte layer having high lithium ion conductivity. The lithium ions (Li + ) can be intercalated between particles of an anode active material such as graphite, or can be deposited and stored in the form of lithium metal.

[0078] The anode according to an embodiment of the present disclosure includes a lithium-philic material that can form an alloy with lithium on the surface of the plate-type carbon material 211 , so when the all-solid-state battery is charged, for example, lithium ions can be stored in the form of an alloy on the surface of the coating 212 .

[0079] In one embodiment, the thickness of the coating layer 212 may be 20 nm to 200 nm. When the thickness of the coating layer 212 is less than 20 nm, the content of the lithium-philic material contained in the coating layer 212 is too small, and thus, the capacity characteristics of the all-solid-state battery may be deteriorated. When the thickness of the coating layer 212 exceeds 200 nm, the volume expansion of the all-solid-state battery may become serious.

[0080] In one embodiment, the anode active material 210 may include 10 wt% to 60 wt% of the coating layer 212 relative to the total weight of the anode active material 210. When the amount of the coating layer 212 is less than 10 wt% relative to the total weight of the anode active material 210, the amount of the lithium-philic material contained in the coating layer 212 is too small, and thus, the capacity characteristics of the all-solid-state battery may be deteriorated. When the amount of the coating layer 212 exceeds 60 wt% relative to the total weight of the anode active material 210, the volume expansion of the all-solid-state battery may become serious.

[0081] In one embodiment, the anode active material layer 200 may include an inorganic electrolyte 220 . Figure 5 2 is a plan view of an anode active material layer 200 including an anode active material 210 and an inorganic electrolyte 220 according to an embodiment of the present disclosure. Figure 5 The inorganic electrolyte 220 may fill the spaces between the particles of the anode active material 210, thereby improving the lithium ion conductivity in the anode active material layer 200. Thus, it may become easier to form a lithium alloy on the surface of the coating layer 212 during charge and discharge.

[0082] Specifically, the inorganic electrolyte 220 may be a solid electrolyte having lithium ion conductivity. The inorganic electrolyte 220 may include an oxide-based inorganic electrolyte, a sulfide-based inorganic electrolyte, or the like. Preferably, a sulfide-based inorganic electrolyte having high lithium ion conductivity may be used. The sulfide-based inorganic electrolyte may include Li 2 SP 2 S 5 , Li 2 SP 2 S 5 -LiI, Li 2 SP 2 S 5 -LiCl, Li 2 SP 2 S 5 -LiBr, Li 2 SP 2 S 5 -Li 2 O. Li 2 SP 2 S 5 -Li 2 O-LiI、Li2 S-SiS 2 , Li 2 S-SiS 2 -LiI, Li 2 S-SiS 2 -LiBr, Li 2 S-SiS 2 -LiCl, Li 2 S-SiS 2 -B 2 S 3 -LiI, Li 2 S-SiS 2 -P 2 S 5 -LiI, Li 2 SB 2 S 3 , Li 2 SP 2 S 5 -Z m S n (m and n are positive numbers, and Z is one of Ge, Zn and Ga), Li 2 S-GeS 2 , Li 2 S-SiS 2 -Li 3 PO 4 , Li 2 S-SiS 2 -Li x MO y (x and y are positive numbers, and M is one of P, Si, Ge, B, Al, Ga, and In), Li 10 G 2 S 12 etc., but not limited to specific materials.

[0083] Oxide-based inorganic electrolytes may include perovskite-type LLTO (Li 3x La 2 / 3-x TiO 3 ), phosphate-based NASICON-type LATP (Li 1+x Al x Ti 2-x (PO 4 ) 3 ) etc. The inorganic electrolyte may be the same as or different from the solid electrolyte included in the solid electrolyte layer 300, which will be described below.

[0084] In addition, the anode active material layer 200 may further include a conductive material, a binder, etc. The conductive material may be carbon black, conductive graphite, ethylene black, vapor-grown carbon fiber, graphene, and the like.

[0085] The binder may include butadiene rubber, nitrile rubber, hydrogenated nitrile rubber, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), carboxymethyl cellulose (CMC), and the like.

[0086] The solid electrolyte layer 300 may be located between the cathode active material layer 400 and the anode active material layer 200 , and may include a solid electrolyte having lithium ion conductivity.

[0087] The solid electrolyte may include an oxide-based solid electrolyte, a sulfide-based solid electrolyte, etc. Preferably, a sulfide-based solid electrolyte having high lithium ion conductivity may be used.

[0088] Sulfide-based solid electrolytes may include Li 2 SP 2 S 5 , Li 2 SP 2 S 5 -LiI, Li 2 SP 2 S 5 -LiCl, Li 2 SP 2 S 5 -LiBr, Li 2 SP 2 S 5 -Li 2 O. Li 2 SP 2 S 5 -Li 2 O-LiI、Li 2 S-SiS 2 , Li 2 S-SiS 2 -LiI, Li 2 S-SiS 2 -LiBr, Li 2 S-SiS 2 -LiCl, Li 2 S-SiS 2 -B 2 S 3 -LiI, Li 2 S-SiS 2 -P 2 S 5 -LiI, Li 2 SB 2 S 3 , Li 2 SP 2 S 5 -Zm S n (m and n are positive numbers, and Z is one of Ge, Zn and Ga), Li 2 S-GeS 2 , Li 2 S-SiS 2 -Li 3 PO 4 , Li 2 S-SiS 2 -Li x MO y (x and y are positive numbers, and M is one of P, Si, Ge, B, Al, Ga, and In), Li 10 G 2 S 12 etc., but not limited to a specific material. The oxide-based solid electrolyte may include perovskite-type LLTO (Li 3x La 2 / 3-x TiO 3 ), phosphate-based NASICON-type LATP (Li 1+ x Al x Ti 2-x (PO 4 ) 3 )wait.

[0089] The solid electrolyte included in the solid electrolyte layer 300 may be the same as or different from the inorganic electrolyte 220 included in the anode active material layer 200 .

[0090] The cathode active material layer 400 may include a cathode active material, a solid electrolyte, a conductive material, a binder, etc. The cathode active material may intercalate and deintercalate lithium ions therein and may include: a rock salt layer type active material such as LiCoO 2 、LiMnO 2 、LiNiO 2 、LiVO 2 or Li 1+x Ni 1 / 3 Co 1 / 3 Mn 1 / 3 O 2 , spinel active materials such as LiMn 2 O 4 Or Li(Ni 0.5 Mn 1.5 ) 4 , inverse spinel active materials such as LiNiVO 4 or LiCoVO 4 , olivine-type active materials such as LiFePO 4 、LiMnPO 4, LiCoPO 4 or LiNiPO 4 , a silicon-containing active material such as Li 2 FeSiO 4 or Li 2 MnSiO 4 , a rock salt layer-type active material in which some transition metals are replaced by another metal, such as LiNi 0.8 Co (0.2-x) Al x O 2 (0 < x < 0.2), a spinel-type active material in which some transition metals are replaced by another metal, such as Li 1+x Mn 2-x-y M y O 4 (M is one of Al, Mg, Co, Fe, Ni or Zn, and 0 < x + y < 2)), lithium titanate such as Li 4 Ti 5 O 12 , etc.

[0091] The solid electrolyte, conductive material, and binder included in the cathode active material layer 400 are substantially the same as the above solid electrolyte, conductive material, and binder, and thus their detailed descriptions will be omitted.

[0092] The cathode current collector 500 can be a plate-shaped substrate having conductivity. For example, the cathode current collector 500 can include aluminum foil. Here, the thickness of the cathode current collector 500 can be, for example, 1 μm to 500 μm, and is not limited to a specific value.

[0093] The volume expansion rate of the all-solid-state battery according to an embodiment of the present disclosure can be less than that of an all-solid-state battery using a conventional spherical carbon material having the same discharge capacity. In one embodiment, the all-solid-state battery according to an embodiment of the present disclosure satisfies the following equation.

[0094] Equation:

[0095] (V 100 -V 0 ) / V 0 ×100 ≤ 12%

[0096] In the equation, V 100 is the volume of the anode active material layer 200 of the all-solid-state battery in a fully discharged state after 100 charge and discharge cycles, and V 0 is the volume of the anode active material layer 200 of the all-solid-state battery when no charge and discharge is performed.

[0097] The above equation can represent the volume expansion rate of the all-solid-state battery. Here, when (V 100-V 0 ) / V 0 When ×100 exceeds 12%, lithium dendrites may be irreversibly formed in the anode active material layer 200 or a large number of voids may be formed between particles of the anode active material 210, and thus, electrochemical characteristics of the all-solid-state battery may be deteriorated.

[0098] Method for manufacturing anode for all-solid-state battery

[0099] According to another embodiment of the present disclosure, a method for manufacturing an anode for an all-solid-state battery may be provided, comprising preparing precursors of a plate-type carbon material 211 and a lithium-philic material, synthesizing an anode active material 210 comprising a plate-type carbon material 211 and a coating 212 arranged to coat at least a portion of a surface of the plate-type carbon material 211, and stacking an anode active material layer 200 comprising the anode active material 210 on an anode current collector 100, wherein the length ratio (a / c) of the major axis a to the thickness c of the plate-type carbon material 211 may be greater than 4, and wherein the coating 212 may include a lithium-philic material from the precursor.

[0100] In one embodiment, the coating 212 can be prepared using chemical vapor deposition. Chemical vapor deposition is a process of depositing a solid material on the surface of any substrate by converting the solid material into a gas phase. The commonly used chemical vapor deposition method can be used to deposit a lithium-philic material, such as silicon (Si), on the surface of a carbon material.

[0101] When chemical vapor deposition is used to prepare the coating 212, the precursor may be a gas phase molecule including a lithium-philic material. For example, the precursor may include a selected from SiH 4 、Si 2 H 6 、Si 3 H 8 、SiCl 4 、SiHCl 3 、Si 2 Cl 6 、SiH 2 Cl 2 、SiH 3 Cl, and combinations thereof.

[0102] In one embodiment, the length ratio (a / c) of the major axis a to the thickness c of the plate-type carbon material 211 may be 4.130 to 5.987 or more generally 4 to 6.

[0103] In one embodiment, the average orientation angle of the major axis a of the plate-type carbon material 211 relative to the plane direction of the anode current collector 100 may be 12° or less.

[0104] In one embodiment, the coating 212 may have a thickness of 20 nm to 200 nm.

[0105] In one embodiment, the anode active material layer 200 may include an inorganic electrolyte 220. Here, the weight ratio of the anode active material 210 to the inorganic electrolyte 220 included in the anode active material layer 200 may be 1:0.5 to 1:1. When the weight ratio of the anode active material 210 to the inorganic electrolyte 220 is less than 1:0.5, the amount of the inorganic electrolyte 220 is too small, and thus, the lithium ion conductivity of the anode active material layer 200 may be reduced, and delamination may occur between the anode active material 210 and the inorganic electrolyte 220. When the weight ratio of the anode active material 210 to the inorganic electrolyte 220 exceeds 1:1, the amount of the inorganic electrolyte 220 is too large, and thus, the energy density of the all-solid-state battery may be reduced.

[0106] The anode manufactured by this manufacturing method is basically the same as the anode of the above-mentioned all-solid-state battery, so its redundant description will be omitted.

[0107] Hereinafter, the embodiments of the present disclosure will be described in more detail through the following examples and comparative examples. The following examples and comparative examples are only used to exemplarily describe the embodiments of the present disclosure, and are not intended to limit the scope and spirit of the embodiments of the present disclosure.

[0108] Manufacturing Example 1-Plate-type carbon material and Si coating

[0109] (a) A plate-shaped carbon material 211 having a length ratio (a / c) of its major axis a to its thickness c controlled within a specified range and silane (SiH 4 )gas.

[0110] (b) The plate-shaped carbon material 211 is placed in a vacuum reactor used in chemical vapor deposition (CVD), and the vacuum reactor is placed in a vacuum. After the vacuum reactor is heated to a temperature of 1100° C., the prepared silane (SiH 4 ) gas was supplied to the inside of the vacuum reactor, and the surface of the plate-type carbon material 211 was coated with the coating layer 212 including the lithium-philic material for 30 minutes. The anode active material 210 according to Manufacturing Example 1 was synthesized through the above process.

[0111] Comparative Manufacturing Example 1 - Spherical Carbon Material and Si Coating

[0112] The anode active material 210 was synthesized by the same process as in Manufacturing Example 1 except that a spherical carbon material was used instead of a plate-type carbon material configured such that the length ratio (a / c) of its major axis a to thickness c was controlled within a specified range.

[0113] In order to confirm the length ratio (a / c) of the major axis a to the thickness c of the spherical carbon material, a scanning electron microscope (SEM) image of the spherical carbon material was obtained, as shown in Figures 8A to 8D shown.

[0114] Comparative Manufacturing Example 2-Plate-Type Carbon Material

[0115] The same plate-type carbon material as in Manufacturing Example 1 was prepared as an anode active material.

[0116] Test Example 1-Measurement of the length ratio (a / c) of the major axis a to the thickness c of the carbon material

[0117] In order to confirm the length ratio (a / c) of the long axis a to the thickness c of the prepared carbon material, the side and front sides of the plate-type carbon material 211 prepared in step (a) of Manufacturing Example 1 were photographed four times each using a scanning electron microscope (SEM) by changing the measurement positions of the side and front sides of the plate-type carbon material 211. Figures 6A to 6D are SEM images of different positions on the side of the plate-shaped carbon material 211. Figures 7A to 7D 1 and 2 are SEM images of different positions on the front surface of the plate-shaped carbon material 211 .

[0118] In addition, the spherical carbon material was photographed four times using a scanning electron microscope (SEM) by changing the measurement position of the spherical carbon material. FIG. 8A to FIG. 8D are SEM images of spherical carbon materials at different locations.

[0119] from Figures 6A to 6D The lengths of the major axis a and the thickness c at various positions of the plate-type carbon material 211 observed and their length ratios (a / c) and the lengths of the major axis a and the thickness c at various positions of the spherical carbon material observed from 8A to 8D and their length ratios (a / c) are listed in the following Table 1. In the spherical carbon material, of two different axes perpendicular to each other, the longer axis is defined as the major axis a, and the shorter axis is defined as the thickness c.

[0120] Table 1

[0121]

[0122] As shown in Table 1, it is confirmed that the length ratio (a / c) of the major axis a to the thickness c of the plate-type carbon material 211 according to the embodiment of the present disclosure is in the numerical range of 4.130 to 5.987, or more generally 4 to 6.

[0123] In addition, from Figures 7A to 7D The lengths of the major axis a and the minor axis b at various positions of the observed plate-type carbon material 211 and their length ratio (a / b) are listed in the following Table 2. Here, of two different axes perpendicular to each other, the longer axis is defined as the major axis a, and the shorter axis is defined as the minor axis b.

[0124] Table 2

[0125]

[0126] As shown in Table 2, it was confirmed that the length ratio (a / b) of the major axis a to the minor axis b of the plate-type carbon material 211 according to the embodiment of the present disclosure was within a numerical range of 1.120 to 2.054.

[0127] Example 1

[0128] (a) The anode active material 210 according to Preparation Example 1 and Li 220 as the sulfide-based inorganic electrolyte 220 having an argyrodite-type crystal structure were prepared in a weight ratio of 58:39:2:1. 6 PS 5 Cl, butadiene rubber as a binder, and vapor grown carbon fiber (VGCF) as a conductive material.

[0129] (b) Anode active material slurry is prepared by placing anode active material 210, inorganic electrolyte 220, binder and conductive material into hexyl butyrate used as a solvent and mixing them. Here, the weight ratio of hexyl butyrate to the anode active material 210, inorganic electrolyte 220, binder and conductive material prepared in step (a) is 6.3:93.7.

[0130] (c) An anode in which an anode active material layer 200 is stacked on the anode current collector 100 is obtained by applying an anode active material slurry to a nickel (Ni) thin film serving as an anode current collector 100, and then drying the slurry in an argon (Ar) environment at a temperature of 80° C. for 10 minutes and drying it in an oven at a temperature of 100° C. under vacuum for more than 2 hours.

[0131] (d) The anode, including Li 6 PS 5 The solid electrolyte layer 300 of Cl (as a sulfide-based inorganic electrolyte with an argyrodite-type crystal structure) and a lithium (Li) thin film are sequentially stacked and then pressed to manufacture an all-solid-state battery cell. Here, the discharge capacity of the manufactured all-solid-state battery cell is set to about 1000 mAh / g.

[0132] Comparative Example 1

[0133] The all-solid-state battery cell according to Comparative Example 1 was manufactured by the same process as Example 1 except that the anode active material 210 according to Comparative Manufacturing Example 1 was used. Here, the discharge capacity of the manufactured all-solid-state battery cell was set to about 1000 mAh / g.

[0134] Comparative Example 2

[0135] (a) The anode active material 210 according to Comparative Manufacturing Example 2, butadiene rubber as a binder, and vapor grown carbon fiber (VGCF) as a conductive material were prepared at a weight ratio of 58:2:1.

[0136] (b) Anode active material slurry is prepared by placing anode active material 210, a binder and a conductive material into hexyl butyrate used as a solvent and mixing them. Here, the weight ratio of hexyl butyrate to the anode active material 210, the binder and the conductive material prepared in step (a) is 6.3:93.7.

[0137] (c) An anode in which an anode active material layer 200 is stacked on the anode current collector 100 is obtained by applying an anode active material slurry to a nickel (Ni) thin film serving as an anode current collector 100, and then drying the slurry in an argon (Ar) environment at a temperature of 80° C. for 10 minutes and drying it in an oven at a temperature of 100° C. under vacuum for more than 2 hours.

[0138] (d) The anode, including Li 6 PS 5 The all-solid-state battery cell according to Comparative Example 2 was manufactured by sequentially stacking a solid electrolyte layer 300 of Cl (as a sulfide-based inorganic electrolyte having an argyrodite-type crystal structure) and a lithium (Li) thin film, and then pressing.

[0139] Test Example 2-Structural Characteristics of All-Solid-State Batteries

[0140] Fig.9A and 9B are SEM images of the cross section of the all-solid-state battery according to Example 1 taken at different magnifications. Fig. 10A and Fig. 10B are SEM images of the cross section of the all-solid-state battery according to Comparative Example 1 taken at different magnifications. Fig.11A and Fig. 11B These are SEM images of the cross section of the all-solid-state battery according to Comparative Example 2 taken at different magnifications.

[0141] Reference Fig.9A and Fig. 9B It can be confirmed that the anode active material layer 200 of the all-solid-state battery according to Example 1 includes an anode active material 210 and an inorganic electrolyte 220, wherein the anode active material 210 includes a plate-type carbon material 211 having plate-type carbon particles arranged in a planar direction parallel to the anode current collector 100, and the inorganic electrolyte 220 is configured to fill the space between the particles of the anode active material 210.

[0142] Reference Fig. 10A and Fig. 10BIt can be confirmed that the anode active material layer 200 of the all-solid-state battery according to Comparative Example 1 includes an anode active material 210 and an inorganic electrolyte 220, wherein the anode active material 210 includes a spherical carbon material having spherical carbon particles randomly arranged along the planar direction of the anode current collector 100, and the inorganic electrolyte 220 is configured to fill the space between the particles of the anode active material 210.

[0143] Reference Fig.11A and Fig. 11B , it can be confirmed that the anode active material layer 200 of the all-solid-state battery according to Comparative Example 2 includes a plate-type carbon material 211 having plate-type carbon particles arranged in parallel to the plane direction of the anode current collector 100, and the arrangement thereof is somewhat random compared to Example 1. In addition, it can be confirmed that the anode active material layer 200 includes a large number of voids formed between particles of the plate-type carbon material 211.

[0144] Test Example 3-Orientation Angle of Plate-Type Carbon Material Relative to Anode Current Collector

[0145] Fig.12 : is a diagram showing the orientation angle of the long axis of the plate-type carbon material 211 included in the all-solid-state battery according to Example 1 and Comparative Example 2 relative to the anode current collector 100. Fig. 9B and 11B The orientation angles of the major axis a of the plate-type carbon material 211 with respect to the anode current collector 100 were observed, and the average value thereof was calculated.

[0146] The average orientation angle of the major axis a of the plate-type carbon material 211 confirmed in Example 1 relative to the anode current collector 100 is 7.00°, and the deviation from the average orientation angle is confirmed to be in the range of -4.86° to +5.58° (ie, -4.86°≤x 1 In addition, the average orientation angle of the major axis a of the plate-type carbon material 211 confirmed by Comparative Example 2 relative to the anode current collector 100 is 12.69°, and the deviation from the average orientation angle is confirmed to be in the range of -10.03° to +10.39° (i.e., -10.03°≤x 2 ≤+10.39°).

[0147] As described above, it was confirmed that the average orientation angle of the major axis a of the plate-type carbon material 211 included in the all-solid-state battery according to Example 1 relative to the anode current collector 100 was lower than the average orientation angle of the major axis a of the plate-type carbon material 211 included in the all-solid-state battery according to Comparative Example 2 relative to the anode current collector 100. That is, in the all-solid-state battery according to Example 1, the plate-type carbon material 211 is arranged more parallel to the plane direction of the anode current collector 100 than in the all-solid-state battery according to Comparative Example 2.

[0148] It is predicted that these results are caused by the anode active material 210 being arranged more regularly during evaporation of the solvent included in the anode active material slurry because the particle strength of the anode active material 210 is increased by coating the surface of the plate-type carbon material 211 with a lithium-philic material such as silicon (Si).

[0149] Test Example 4 - Volume Expansion Rate of Anode Active Material Layer

[0150] The following test was conducted to confirm the volume expansion rate of the anode active material layer 200 .

[0151] First, the thickness of the anode of the all-solid-state batteries according to Example 1 and Comparative Example 1 (in which the charge and discharge cycle was not performed) was measured by a micrometer (293-240-30, manufactured by Mitutoyo), and the thickness V of the anode current collector formed of nickel was subtracted therefrom. 0 , that is 13μm.

[0152] Thereafter, a cross section of the all-solid-state battery according to Example 1 in a fully discharged state after 100 charge and discharge cycles was photographed using a field emission scanning electron microscope (JSM-7401F, manufactured by JEOL), and the obtained SEM image is as follows: Fig.13 As shown, a cross section of the all-solid-state battery according to Comparative Example 1 in a fully discharged state after 100 charge and discharge cycles was photographed using a field emission scanning electron microscope, and the obtained SEM image is as shown Fig.14 shown.

[0153] Measurement Fig.13 and Fig.14 The thickness V of the anode is shown 100 Calculate the volume expansion ratio [(V 100 -V 0 ) / V 0 ×100] and are listed in the following Table 3.

[0154] Table 3

[0155] type <![CDATA[V 0 (μm)]]> <![CDATA[V 100 (μm)]]> Volume expansion rate (%) Example 1 39 40.1 2.8 Comparative Example 1 41 46.1 12.4

[0156] As shown in Table 3, it is confirmed that the volume expansion rate of the anode of the all-solid-state battery using the plate-type carbon material 211 according to Example 1 is much lower than the volume expansion rate of the anode of the all-solid-state battery using the spherical carbon material according to Comparative Example 1.

[0157] Test Example 5-Electrochemical Characteristics of All-Solid-State Batteries

[0158] Fig.15: is a graph showing the evaluation results of the battery characteristics of the all-solid-state batteries according to Example 1 and Comparative Example 1 when the formation process is performed at a rate of 0.1C. Here, the charge and discharge of the all-solid-state battery is performed within a cutoff voltage range of 0.005V to 1.5V.

[0159] also, Fig.16 It is a graph showing the evaluation results of the battery characteristics of the all-solid-state batteries according to Example 1 and Comparative Example 1 when charging and discharging were performed at a rate of 0.3C after the formation process. Here, the charging and discharging of the all-solid-state batteries were performed within a cutoff voltage range of 0.005V to 1.0V.

[0160] In addition, in order to examine the life characteristics of the all-solid-state battery, the capacity retention rate of the all-solid-state battery according to Example 1 and Comparative Example 1 was evaluated while performing 100 charge and discharge cycles, and the evaluation results are as follows: Fig.17 shown.

[0161] Depend on Figures 15 to 17 The results of the confirmed electrochemical characteristics of the all-solid-state battery are listed in Table 4 below.

[0162] Table 4

[0163]

[0164] As shown in Table 4, it was confirmed that the irreversible capacity of the all-solid-state battery according to Example 1 was reduced and the lifespan characteristics were improved compared to the all-solid-state battery according to Comparative Example 1.

[0165] It can be clearly seen from the above description that the anode according to an embodiment of the present disclosure includes: a plate-type carbon material configured so that the length ratio (a / c) of its major axis a to its thickness c is controlled within a specified range, and a coating configured to coat at least a portion of the surface of the plate-type carbon material, thereby minimizing the volume expansion rate of the all-solid-state battery including the anode and improving the life characteristics of the all-solid-state battery.

[0166] The embodiments of the present disclosure have been described in detail with reference to the preferred embodiments of the present disclosure. However, it will be appreciated by those skilled in the art that these embodiments may be modified without departing from the principles and spirit of the embodiments of the present disclosure, and the scope of the embodiments of the present disclosure is defined by the appended claims and their equivalents.

Claims

1. An anode for an all-solid-state battery, the anode comprising: Anode current collector; and an anode active material layer, which is disposed on the anode current collector and comprises an anode active material, wherein the anode active material comprises: A plate-type carbon material, wherein a ratio a / c of ​​a major axis a to a thickness c of the plate-type carbon material is 4 or more; and A coating layer is coated on a portion of the surface of the plate-type carbon material, wherein the coating layer comprises a lithium-philic material. 2 . The anode according to claim 1 , wherein the plate-type carbon material comprises a material selected from the group consisting of natural graphite, artificial graphite, and combinations thereof. 3 . The anode according to claim 1 , wherein a length ratio a / c of ​​a major axis a to a thickness c of the plate-type carbon material is 4.130 to 5.

987. 4 . The anode according to claim 1 , wherein a ratio a / b of a length of a major axis a to a minor axis b of the plate-type carbon material is 1.120 to 2.

054. 5 . The anode according to claim 1 , wherein an average orientation angle of a major axis a of the plate-type carbon material relative to a plane direction of the anode current collector is 12° or less. 6 . The anode according to claim 1 , wherein the lithium-philic material comprises a material selected from the group consisting of silicon Si, silver Ag, magnesium Mg, tin Sn, bismuth Bi, zinc Zn, and combinations thereof.

7. The anode according to claim 1, wherein the lithium-philic material comprises amorphous silicon (Si). The anode according to claim 1 , wherein the coating layer has a thickness of 20 nm to 200 nm. 9 . The anode according to claim 1 , wherein the anode active material comprises 10 wt % to 60 wt % of the coating layer relative to the total weight of the anode active material. 10 . The anode according to claim 1 , wherein the anode active material layer further comprises an inorganic electrolyte.

11. An all-solid-state battery, comprising: An anode, comprising an anode current collector and an anode active material layer disposed on the anode current collector and comprising an anode active material, wherein the anode active material comprises: A plate-type carbon material, wherein a ratio a / c of ​​a major axis a to a thickness c of the plate-type carbon material is 4 or more; and A coating layer coated on a portion of the surface of the plate-type carbon material, wherein the coating layer comprises a lithium-philic material; a solid electrolyte layer disposed on the anode active material layer and comprising a solid electrolyte; a cathode active material layer disposed on the solid electrolyte layer and comprising a cathode active material; and A cathode current collector is disposed on the cathode active material layer.

12. The all-solid-state battery according to claim 11, which is configured to satisfy (V 100 -V0) / V0×100≤12%, where V 100 is the volume of the anode active material layer of the all-solid-state battery in a fully discharged state after 100 charge and discharge cycles, and V0 is the volume of the anode active material layer of the all-solid-state battery in a state where no charge and discharge is performed.

13. A method for manufacturing an anode for an all-solid-state battery, the method comprising: Preparing precursors of plate-type carbon materials and lithium-philic materials; Synthesizing an anode active material, the anode active material comprising: The plate-shaped carbon material, wherein the length ratio a / c of ​​the major axis a to the thickness c of the plate-shaped carbon material is 4 or more; and A coating layer, which is coated on a portion of the surface of the plate-type carbon material, wherein the coating layer comprises a lithium-philic material derived from the precursor; and An anode active material layer including the anode active material is stacked on an anode current collector. 14 . The method according to claim 13 , wherein a length ratio a / c of ​​a major axis a to a thickness c of the plate-type carbon material is 4.130 to 5.

987. 15 . The method according to claim 13 , wherein an average orientation angle of a major axis a of the plate-type carbon material relative to a plane direction of the anode current collector is 12° or less.

16. The method of claim 13, wherein the coating is prepared using chemical vapor deposition.

17. The method of claim 13, wherein the precursor comprises a material selected from the group consisting of SiH4, Si2H6, Si3H8, SiCl4, SiHCl3, Si2Cl6, SiH2Cl2, SiH3Cl, and combinations thereof.

18. The method of claim 13, wherein the coating has a thickness of 20 nm to 200 nm.

19. The method of claim 13, wherein the anode active material layer further comprises an inorganic electrolyte. 20 . The method according to claim 19 , wherein a weight ratio of the anode active material to the inorganic electrolyte contained in the anode active material layer is 1:0.5 to 1:1.

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