Anodeless all solid state battery

Abstract

A non-anode all-solid-state battery comprising a double layer of solid electrolyte layer capable of suppressing dendrite formation and inducing uniform lithium deposition is disclosed. A negative electrode all-solid-state battery according to the present invention comprises a negative electrode current collector; a first solid electrolyte layer doped with silver (Ag) located on the negative electrode current collector; a second solid electrolyte layer located on the first solid electrolyte layer; and a positive electrode located on the second solid electrolyte layer; and is characterized by having an electron conductivity of 1.0 × 10⁻³ S / cm or higher at a discharge voltage of 1.2 V.

Description

Technology Field

[0001] The present invention relates to a non-anode all-solid-state battery having a solid electrolyte layer formed as a double layer. Background Technology

[0003] Lithium solid electrolytes are materials that possess lithium ion conductivity.

[0004] All-solid-state battery technology utilizing solid electrolytes can ensure high energy density and safety.

[0005] Li6PS5Cl, with its azirodite structure, is easy to mass-produce due to its high ionic conductivity and simple synthesis process. Additionally, Li6PS5Cl exhibits soft characteristics resulting from the high sulfur content of sulfide-based solid electrolytes, and a low-resistance interface can be formed through a pressurization process without the need for a separate calcination process.

[0006] The physical characteristics of these materials allow for the manufacturing of batteries using only a pressurization process, making them suitable for producing large-area all-solid-state batteries.

[0007] When a liquid electrolyte is replaced with a solid electrolyte, energy density decreases due to the high density and content of the solid electrolyte within the battery.

[0008] Therefore, lithium metal cathode or cathode-free battery systems must be applied together with the application of solid electrolytes.

[0009] Anode-free batteries are systems with no or minimized cathode material, in which lithium metal deposition occurs between the interface of the solid electrolyte and the current collector during the charging process.

[0010] However, in actual anode-free batteries, dendrite formation, in which lithium metal penetrates into the electrolyte, occurs easily. This is because lithium metal deposition can easily occur within pores or defects present in the solid electrolyte layer, and the solid electrolyte and lithium metal have low wettability.

[0011] In terms of geometry, solid electrolyte powders synthesized by high-temperature sintering and grinding have difficulty forming a uniform interface with metal current collectors.

[0012] During charging, the interface between the solid electrolyte and the current collector is formed mainly through point contact, and there is a problem in that localized lithium metal is deposited only at the parts where physical contact occurs.

[0013] In developing a cathode-free all-solid-state battery capable of simultaneously securing high energy density and stability, it is essential to develop a uniform lithium deposition technology without dendrite formation. The problem to be solved

[0015] The objective of the present invention is to provide a non-anode all-solid-state battery capable of improving electronic conductivity and maintaining ionic conductivity by precipitating Ag metal through an electrochemical reduction reaction in a double-layer structure of a solid electrolyte in which a portion of Li is substituted with Ag.

[0016] In addition, the objective of the present invention is to provide a cathode-free all-solid-state battery capable of inducing uniform lithium deposition.

[0018] The objects of the present invention are not limited to those mentioned above, and other unmentioned objects and advantages of the present invention may be understood from the following description and will be more clearly understood by the embodiments of the present invention. Furthermore, it will be readily apparent that the objects and advantages of the present invention can be realized by the means and combinations thereof set forth in the claims. means of solving the problem

[0020] A negative electrode all-solid-state battery according to the present invention comprises: a negative electrode current collector; a first solid electrolyte layer doped with silver (Ag) located on the negative electrode current collector; a second solid electrolyte layer located on the first solid electrolyte layer; and a positive electrode located on the second solid electrolyte layer; wherein the electron conductivity at a discharge voltage of 1.2V is 1.0 × 10⁻⁶ -3 It is characterized by being greater than S / cm.

[0021] When analyzing the XRD diffraction pattern of the above-mentioned anode-free all-solid-state battery at a discharge voltage of 1.2V, the intensity of the peak on the (311) plane may be greater than the intensity of the peak on the (222) plane.

[0022] At a discharge voltage of 1.2V, the ion conductivity can be 1.0mS / cm or higher.

[0023] When analyzing the XRD diffraction pattern of the above-mentioned anode-free all-solid-state battery at an open-circuit voltage of 2.3V, the intensity of the peak on the (222) plane may be greater than the intensity of the peak on the (311) plane.

[0024] During charging and discharging, the silver (Ag)-doped first solid electrolyte layer may include silver (Ag) metal that is reduced and precipitated from silver (Ag) ions.

[0025] During charging and discharging, the first solid electrolyte layer doped with silver (Ag) may have an argyrodite-type crystal structure.

[0026] The above silver (Ag)-doped first solid electrolyte layer is Li a-b Ag b P c S d X e It may include.

[0027] (The above X includes one or more of F, Cl, Br, and I, and 0 <a≤15, 0.2≤b≤0.6, 0≤c≤3, 0<d≤12, 0≤e≤3이다.)

[0028] The second solid electrolyte layer mentioned above is Li a P c S d X e It may include.

[0029] (The above X includes one or more of F, Cl, Br, and I, and 0 <a≤15, 0≤c≤3, 0<d≤12, 0≤e≤3이다.)

[0030] The thickness of the first solid electrolyte layer doped with silver (Ag) may be 10 nm to 100 µm.

[0031] The above anode may include an anode current collector and an anode material disposed on at least one surface of the anode current collector.

[0032] The above-mentioned cathode material may include one or more cathode active materials among lithium cobalt oxide, lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide, lithium nickel cobalt manganese oxide, lithium manganese oxide, and lithium iron phosphate oxide. Effects of the invention

[0034] The anode-free all-solid-state battery according to the present invention has the effect of improving electronic conductivity and maintaining ionic conductivity by applying a double layer structure of a solid electrolyte in which a portion of Li is substituted with Ag in an azirodite structure solid electrolyte composition composed of lithium and silver (Ag) ions, through the precipitation of Ag metal using an electrochemical reduction reaction.

[0035] In addition, silver (Ag) in the first solid electrolyte layer Ag-Li6PS5Cl provides electrical conductivity and a lithium deposition seed, and the second solid electrolyte layer Li6PS5Cl provides a pathway for the movement of lithium ions, so lithium is deposited uniformly based on very high reversibility, and there is an advantage that the resistance of the battery does not increase during the charging and discharging process.

[0036] In addition, the anode-free all-solid-state battery of the present invention can induce uniform lithium deposition.

[0038] In addition to the effects described above, the specific effects of the present invention are described together with the specific details for implementing the invention below. Brief explanation of the drawing

[0040] FIG. 1 is a cross-sectional view of a cathode-free all-solid-state battery according to the present invention. Figure 2 is Ag + This is a photograph of an azirodite structured solid electrolyte containing [it]. Figure 3 shows Li according to Ag content 6-x Ag xThis is the result of the XRD diffraction pattern analysis of PS5Cl (x= 0, 0.2, 0.4, 0.6). Figure 4 shows Li 6-x Ag x These are the results for the ionic conductivity and activation energy of PS5Cl (x= 0, 0.2, 0.4, 0.6). Figure 5 shows Li 5.4 Ag 0.6 This is the result of the analysis of XRD structural changes of PS5Cl according to voltage. Figure 6 shows Li at OCV (open-circuit voltage) and 1.2V. 5.4 Ag 0.6 These are the measurement results of the ionic conductivity and electronic conductivity of PS5Cl. Figure 7 shows the cross-sectional SEM image results at OCV (open-circuit voltage) (a) and 0V discharge state (b). Fig. 8 is SUS / Li 6-x Ag x PS5Cl / Li6PS5Cl 0.5 Br 0.5 This is the result of the evaluation of the reversibility of Li deposition on the / Li half-paper. Fig. 9 is SUS / Li 5.4 Ag 0.6 PS5Cl / Li6PS5Cl 0.5 Br 0.5 This is the cycle graph of the / Li half-cell. Figure 10 shows the anode / Li6PS5Cl 0.5 Br 0.5 / Li 5.4 Ag 0.6 This is the evaluation result of the PS5Cl / SUS pouch-type cathode-free complete paper. Fig. 11 is SUS / Li 5.1 Ag 0.9 PS5Cl / Li6PS5Cl 0.5 Br 0.5 This is the first cycle graph of the / Li half-cell. Fig. 12 is SUS / Li 5.1 Ag 0.9 PS5Cl / Li6PS5Cl 0.5 Br 0.5 This is the result of the evaluation of the reversibility of Li deposition on the / Li half-paper. Specific details for implementing the invention

[0041] The aforementioned objectives, features, and advantages are described in detail below with reference to the attached drawings, thereby enabling those skilled in the art to easily implement the technical concept of the present invention. In describing the present invention, detailed descriptions of known technologies related to the present invention are omitted if it is determined that such descriptions would unnecessarily obscure the essence of the invention. Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the attached drawings. In the drawings, the same reference numerals are used to indicate the same or similar components.

[0042] In the following, the statement that any configuration is placed on the "upper (or lower)" of a component or on the "upper (or lower)" of a component may mean not only that any configuration is placed in contact with the upper (or lower) surface of said component, but also that another configuration may be interposed between said component and any configuration placed on (or below) said component.

[0043] In addition, where it is stated that one component is "connected," "combined," or "connected" to another component, it should be understood that while the components may be directly connected or connected to each other, another component may be "interposed" between each component, or each component may be "connected," "combined," or "connected" through another component.

[0044] Hereinafter, a negative electrode all-solid-state battery according to some embodiments of the present invention will be described.

[0046] Anode-free all-solid-state batteries can be charged through a process of lithium metal deposition at the interface between the solid electrolyte and the negative electrode current collector. However, the low affinity of lithium metal for the solid electrolyte and defects present in the solid electrolyte layer accelerate the formation of lithium dendrites. Furthermore, solid electrolytes with irregular shapes form an incomplete interface with the negative electrode current collector even after the pressurization process, and localized lithium metal formation occurs only in the contact area during charging. There is an urgent need to develop new solid electrolyte compositions to solve these problems.

[0048] The present invention develops a sulfide-based lithium solid electrolyte composition composed of heterocations of Li and Ag, fabricates a double-layer solid electrolyte using this, and induces a silver (Ag) metal extraction reaction from the silver (Ag)-doped solid electrolyte among them, thereby improving the performance of a non-anode all-solid-state battery.

[0050] FIG. 1 is a cross-sectional view of a cathode-free all-solid-state battery according to the present invention.

[0051] As illustrated in FIG. 1, a negative electrode all-solid-state battery according to the present invention comprises a negative electrode current collector (10), a first solid electrolyte layer (20) doped with silver (Ag) located on the negative electrode current collector, a second solid electrolyte layer (30) located on the first solid electrolyte layer, and a positive electrode (40) located on the second solid electrolyte layer, wherein the electron conductivity at a discharge voltage of 1.2V is 1.0 × 10 -3 It is characterized by being greater than S / cm.

[0053] negative current collector (10)

[0054] The negative current collector (10) may be a plate-shaped substrate that is electrically conductive.

[0055] Specifically, the negative current collector may be in the form of a sheet, a thin film, or a foil.

[0056] The cathode current collector may be a high-density metal thin film with a porosity of about 1% or less. In addition, the cathode current collector may have a thickness of 1 μm to 20 μm, and specifically, 5 μm to 15 μm.

[0057] The negative electrode current collector may include a material that does not react with lithium. For example, the negative electrode current collector may include at least one selected from the group consisting of Ni, Cu, SUS (Stainless Steel), and combinations thereof.

[0059] First solid electrolyte layer (20) and second solid electrolyte layer (30)

[0060] A double layer of solid electrolyte may be located on the cathode current collector.

[0061] The double-layered solid electrolyte layer includes a first solid electrolyte layer and a second solid electrolyte layer, and the double-layered solid electrolyte layer inhibits the formation of dendrites in which lithium metal penetrates into the electrolyte and forms a space for Li to grow.

[0062] The first solid electrolyte layer is a layer in contact with the negative current collector and may include a silver (Ag)-doped sulfide-based compound.

[0063] The second solid electrolyte layer may include a sulfide-based compound.

[0064] Here, the sulfide compound is Li a P c S d X e (The above X includes one or more of F, Cl, Br, and I, and 0 <a≤15, 0≤c≤3, 0<d≤12, 0≤e≤3이다.)를 포함할 수 있다.

[0065] Sulfide compounds are preferably Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2) and Li 7-x PS6-x I x It may include one or more of (0≤x≤2), and more preferably Li 7-x PS 6-x Cl x (0≤x≤2) and, more preferably, Li6PS5Cl.

[0067] The first solid electrolyte layer has a solid electrolyte composition of an azirodite structure composed of lithium and silver ions.

[0068] The first solid electrolyte layer doped with silver (Ag) is Li a-b Ag b P c S d X e It may include.

[0069] (The above X includes one or more of F, Cl, Br, and I, and 0 <a≤15, 0.2≤b≤0.6, 0≤c≤3, 0<d≤12, 0≤e≤3이다.)

[0070] Li of the first solid electrolyte layer a-b Ag b P c S d X e In this case, the Ag content may be 0.2≤b≤0.6, and preferably 0.4≤b≤0.6.

[0071] By satisfying the Ag content of 0.2≤b≤0.6, there is an excellent effect of reversibility in the deposition and detachment of Ag.

[0073] The second solid electrolyte layer is the Li a P c S d X e It includes and has an agyrodite structure.

[0074] (The above X includes one or more of F, Cl, Br, and I, and 0 <a≤15, 0≤c≤3, 0<d≤12, 0≤e≤3이다.)

[0076] Li6PS5Cl, which constitutes the solid electrolyte layer, has a structure that allows for the movement of lithium ions, and by substituting some of the Li with Ag, it forms a structure that allows Li and silver (Ag) ions to move simultaneously.

[0077] Li and Ag are substances in which monovalent ions are stable, so silver (Ag)-doped Li6PS5Cl can be synthesized by substituting a portion of the LiCl precursor with AgCl during synthesis.

[0078] In addition, in Ag-doped Li6PS5Cl, at a voltage of 0.8 V relative to Li, the precipitation of Ag occurs through the migration of silver (Ag) ions and an electrochemical reduction reaction.

[0079] In this regard, the inventors prepared Li6PS5Cl doped with silver (Ag) as a first solid electrolyte layer and Li6PS5Cl as a second solid electrolyte layer.

[0080] As a first solid electrolyte layer, silver (Ag)-doped Li6PS5Cl can form Ag-Li6PS5Cl by precipitating Ag during the charging process.

[0081] In Ag-Li6PS5Cl as the first solid electrolyte layer, silver (Ag) provides electrical conductivity and a lithium deposition seed.

[0082] The second solid electrolyte layer is located between the first solid electrolyte layer and the anode, and can conduct lithium ions between the two components.

[0083] As a second solid electrolyte layer, a solid electrolyte that does not contain silver can be used, and Li6PS5Cl enables the configuration of the battery by providing a pathway for the movement of lithium ions and forming an insulating layer.

[0085] If a non-anode all-solid-state battery is composed of a single second solid electrolyte layer without a first solid electrolyte layer doped with silver (Ag), there is a problem of localized lithium metal deposition because Li grows only in one place.

[0086] In addition, if the solid electrolyte and silver (Ag) powder are physically mixed and used instead of using a first solid electrolyte layer doped with silver (Ag), the silver (Ag) powder is not uniformly dispersed within the solid electrolyte layer.

[0087] Accordingly, when a solid electrolyte and silver (Ag) powder are physically mixed and used, the reversibility is reduced, and a short circuit occurs at 50 cycles, causing the battery to fail to operate.

[0089] Accordingly, as in the present invention, it is desirable to stack a first solid electrolyte layer doped with silver (Ag) and a second solid electrolyte layer located on the first solid electrolyte layer to simultaneously secure high energy density and stability while inducing uniform lithium deposition without dendrite formation.

[0091] When analyzing the XRD diffraction pattern of the above-mentioned anode-free all-solid-state battery at a charging voltage of 2.3V, the intensity of the peak on the (222) plane may be greater than the intensity of the peak on the (311) plane.

[0092] On the other hand, when analyzing the XRD diffraction pattern of the above-mentioned anode-free all-solid-state battery at a discharge voltage of 1.2V, the intensity of the peak on the (311) plane may be greater than the intensity of the peak on the (222) plane.

[0093] In a typical azirodite structure, the (311) plane shows higher strength than the (222) plane.

[0094] Since the (222) plane in the crystal plane is occupied by Li and Ag, the greater the Ag content, the stronger the strength of the (222) plane becomes as Li is substituted for Ag.

[0095] In the synthesized anode-free all-solid-state battery, silver (Ag) in the first solid electrolyte layer exists in an ionic state and is reduced to a metal upon charging, at which time the first solid electrolyte layer maintains its azirodite structure.

[0096] And, when the discharge starts close to 0V, the silver (Ag) in the first solid electrolyte layer continues to precipitate, and the (222) plane becomes weak and the (311) plane becomes strong.

[0098] While the discharge continues to proceed while lowering the voltage, silver (Ag) in the first solid electrolyte layer continues to precipitate, and a Li-Ag compound with a high Li content can continue to be formed in the first solid electrolyte layer.

[0099] Li-Ag compounds may include Ag-Li alloys, which have an azirodite structure.

[0100] The above alloy is generally classified into solid solutions and intermetallic compounds, and the above Li-Ag compound may be a metallic compound or a solid solution.

[0101] Metal compounds exhibit a crystal structure formed by any two solid components, and various crystal structural phases of compound structures can exist between Li and Ag.

[0102] A solid solution refers to a single, uniform solid formed by dissolving another solid into any solid, where atoms of different solids can be mixed to form a single crystal structure. The solid solution can be classified into interstitial solid solutions, in which atoms of another element are inserted into the gaps between atoms, and substitutional solid solutions, in which atoms displace the atoms of a solid that are arranged in order and take their place.

[0103] If the atomic sizes of lithium and the element forming the alloy with the lithium are similar to each other, the lithium alloy can exist in the form of a substitutional solid solution.

[0104] If there is a large difference in the atomic size of lithium and the element, it can exist in the form of an interstitial solid solution. For example, in Li-Ag compounds, when the proportion of Li is high, the Li-Ag alloy can exist in the form of a substitutional solid solution.

[0106] When voltage is applied to a cathode-free all-solid-state battery to charge it, lithium is released in the form of ions from the positive active material present in the positive electrode and moves toward the negative electrode.

[0107] Lithium ions released from the above positive electrode active material can form Li-Ag compounds, such as Ag-Li alloys, as they pass through a first solid electrolyte layer with high lithium ion conductivity.

[0109] At a discharge voltage of 1.2 V, which is the voltage at which Ag metal is formed, the electron conductivity is 1.0 × 10⁻⁶ -3 It may be greater than S / cm, and preferably 2.5 x 10 -3 It may be greater than S / cm.

[0110] The reason such high electronic conductivity can be achieved is that the electrochemically formed Ag continuously forms channels that provide electronic conductivity.

[0111] This means that during the discharge process, an insulating solid electrolyte is converted into a solid electrolyte with high electronic conductivity through electrochemical reactions.

[0113] At a discharge voltage of 1.2V, which is the voltage at which Ag metal is formed, the ion conductivity can be maintained at 1.0mS / cm or higher without significant decrease.

[0114] It is believed that the reason ionic conductivity can be maintained is that as silver (Ag) precipitates, it forms a Li-Ag compound, and the empty spaces of silver (Ag) provide sites for the movement of Li ions, thereby maintaining Li ion conductivity.

[0116] As such, the first solid electrolyte layer doped with silver (Ag) during charging and discharging may contain silver (Ag) metal that is reduced and precipitated from silver (Ag) ions.

[0117] In addition, the first solid electrolyte layer doped with silver (Ag) during charging and discharging may have an argyrodite-type crystal structure.

[0119] The thickness of the first solid electrolyte layer doped with silver (Ag) can be 10 nm to 100 µm.

[0120] If the thickness is less than 10 nm, it is difficult to fabricate the first solid electrolyte layer, and lithium metal may be deposited unevenly on the first solid electrolyte layer.

[0121] If the thickness of the first solid electrolyte layer exceeds 100 μm, the energy density of the above-mentioned anode-free all-solid-state battery may decrease.

[0123] positive electrode (40)

[0124] The positive electrode may include a positive electrode current collector and a positive electrode material disposed on at least one surface of the positive electrode current collector.

[0126] The anode can generate and consume electrons through electrochemical reactions and performs the function of supplying electrons to an external circuit through the anode current collector.

[0127] The positive electrode is not specifically limited, but any positive electrode formed by applying a slurry for the positive electrode material to at least one surface of a positive electrode current collector, drying, and rolling, and any positive electrode commonly used in secondary batteries can be suitably used in the present invention.

[0128] The slurry for the cathode material comprises a cathode active material, a binder, and a solvent, and may include a conductive material as needed.

[0129] As a positive electrode active material, a compound capable of reversible insertion and extraction of lithium may be used. Specifically, one or more composite oxides of lithium and a metal selected from cobalt, manganese, nickel, and combinations thereof may be used.

[0130] A more specific example is a lithium transition metal compound (oxide) with a layered structure represented by the general formula LiMO2, wherein M includes at least one of the transition metal elements such as Ni, Co, and Mn, and may additionally include other metal elements or non-metal elements.

[0131] Examples of the above composite oxides include, for instance, a monolithic lithium transition metal composite oxide containing one of the above transition metal elements, a so-called binary lithium transition metal composite oxide containing two of the above transition metal elements, and a ternary lithium transition metal composite oxide containing Ni, Co, and Mn as constituent elements as transition metal elements.

[0132] A lithium transition metal compound (oxide) represented by the general formula Li2MO3, wherein M comprises at least one of the transition metal elements such as Mn, Fe, and Co, and may additionally comprise other metal elements or non-metal elements, such as Li2MnO3 and Li2PtO3.

[0133] Preferably, the cathode material may include one or more cathode active materials selected from lithium cobalt oxide, lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide, lithium nickel cobalt manganese oxide, lithium manganese oxide, and lithium iron phosphate oxide.

[0135] Furthermore, a coating layer on the surface of the positive active material may be used, or a mixture of the compound and the compound having the coating layer may be used.

[0136] The coating layer may comprise at least one coating element compound selected from the group consisting of oxides, hydroxides, oxyhydroxides, oxycarbonates, and hydroxycarbonates of the coating element. The compounds forming the coating layer may be amorphous or crystalline. The coating elements included in the coating layer may be Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or mixtures thereof.

[0137] The binder serves to bind the positive active material particles together and also bind the positive active material to the positive current collector.

[0138] For example, the binder may be polyvinyl alcohol, carboxymethylcellulose, hydroxypropylcellulose, diacetylcellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, a polymer containing ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, etc.

[0139] The above conductive material is used to impart conductivity to the anode, and any electronically conductive material commonly used in the anode of a secondary battery can be suitably used.

[0140] The above solvent may be an aqueous solvent such as water, as well as a solvent with low polarity or a non-aqueous solvent. As for the above-mentioned non-aqueous solvent, any solvent that does not chemically react with or causes minimal chemical reaction with the solid electrolyte in the manufacture of the cathode material of a secondary battery may be used in the present invention. Examples include butyl butyrate, tetrahydrofuran, ethyl acetate, and N-methyl-2-pyrrolidone (NMP), but are not limited thereto.

[0141] As a positive current collector, a metal with good conductivity such as aluminum, nickel, titanium, stainless steel, etc., can be used, and it can be in various forms such as sheet type, thin type, mesh type, etc. The thickness of the positive current collector is not particularly limited and can be, for example, 5 to 30 μm.

[0142] As described above, an anode can be manufactured by applying a slurry for the anode material to at least one surface of the anode current collector, and then drying and rolling, thereby forming an anode material on the anode current collector.

[0144] As such, specific embodiments of the anode-free all-solid-state battery are as follows.

[0146] 1. Manufacture of anode-free all-solid-state batteries

[0147] Figure 2 is a photograph of an azirodite structure solid electrolyte containing Ag+.

[0148] Li6PS5Cl with an azirodite structure is synthesized through the mixing and heat treatment of Li2S, P2S5, and LiCl.

[0149] When a portion of the LiCl is replaced with AgCl, a solid electrolyte with an azirodite structure in which Ag is substituted for the Li site is synthesized from the same synthesis process.

[0150] The same effect can be achieved by replacing Li2S with Ag2S.

[0151] The synthesis heat treatment temperature can be 300 to 600℃, and synthesis can be performed in a vacuum atmosphere or an argon atmosphere.

[0152] Figure 2 shows a photograph of solid electrolyte powder synthesized at 550°C.

[0153] The synthesized powder can be recovered in powder form through a grinding process and has a grayish-white color, which is the characteristic color of solid electrolytes.

[0155] Figure 3 shows Li according to Ag content 6-x Ag xThis is the result of the XRD diffraction pattern analysis of PS5Cl (x= 0, 0.2, 0.4, 0.6).

[0156] The synthesis process was carried out by replacing a portion of the LiCl with AgCl according to the molar amount, and the XRD analysis results of the synthesized powder are shown in Figure 3.

[0157] Li 6-x Ag x The content of x in PS5Cl is 0, 0.2, 0.4, and 0.6.

[0158] All samples maintained the azirodite structure regardless of the Ag ratio.

[0159] In addition, as the Ag content increased, the XRD peak diffraction shifted to the left, which is because the monovalent Ag ion is larger than the monovalent Li ion.

[0160] In a typical azirodite structure, the (311) plane shows higher strength than the (222) plane, and it can be seen that the strength of the (222) plane increases as more Ag is included.

[0161] This is also a phenomenon that occurs as high molecular weight Ag is substituted into the (222) plane, which has a high proportion of Li.

[0162] XRD results indicate that Ag was successfully doped into the Li sites within the Li6PS5Cl structure.

[0164] Figure 4 shows Li 6-x Ag x These are the results for the ionic conductivity and activation energy of PS5Cl (x= 0, 0.2, 0.4, 0.6).

[0165] To verify the ionic conductivity of the solid electrolyte, impedance resistance analysis was performed under pressurized conditions.

[0166] The analysis method is as follows.

[0167] 150 mg of solid electrolyte is placed in an insulating mold with a diameter of 13 mm and pressurized at 500 MPa for 1 minute. Then, titanium molds are brought into contact with both sides of the solid electrolyte, and the impedance resistance is measured while maintaining a pressure of 60 MPa.

[0168] As a result, the ionic conductivity of Li6PS5Cl was measured to be 2.0 mS / cm, and the ionic conductivity showed a tendency to decrease as the Ag content increased.

[0169] These results also show a connection with activation energy, and it can be confirmed that activation energy increases along with a decrease in ion conductivity.

[0170] Although Ag present at the Li site reduces overall ion mobility, an ion conductivity of 1.0 mS / cm or higher is still maintained.

[0171] Regardless of the Ag content, the electronic conductivity of all materials is e -10 A value close to that of an insulating material was confirmed in S / cm.

[0173] Figure 5 shows Li 5.4 Ag 0.6 This is the result of the analysis of XRD structural changes of PS5Cl according to voltage.

[0174] To evaluate the electrochemical reactivity of an Ag-containing Li6PS5Cl solid electrolyte, a Li half-cell was constructed, and XRD structural analysis was performed according to voltage during the lithium insertion discharge process.

[0175] The substance is Li 5.4 Ag 0.6 PS5Cl was selected.

[0176] SUS / Li 5.4 Ag 0.6 A half-cell was constructed with PS5Cl / Li6PS5Cl / Li, and the OCV was measured at 2.3V during cell fabrication.

[0177] At an initial 2.3V, it maintained the previously identified agyrodite structure, and when XRD analysis was performed according to discharge voltage, an XRD peak originating from Ag metal was observed at 1.2V.

[0178] Li6PS5Cl was still present even as the XRD peak of Ag was confirmed, which means that the Li6PS5Cl structure is maintained when Ag existing in an ionic state within the solid electrolyte undergoes an electrochemical reduction reaction during the discharge process to form Ag metal.

[0179] Even during deeper discharge processes, XRD peaks were confirmed while the Li6PS5Cl structure was maintained, and Ag sequentially formed a Li-rich alloy phase of Li-Ag.

[0180] This means that the solid electrolyte forms Ag-Li6PS5Cl during the discharge process, and Li6PS5Cl and Ag provide ion and electron conduction channels.

[0181] Additionally, it can be observed that from the point where Ag ions are released and Ag metal is formed, the peak on the (311) plane becomes stronger than the peak on the (222) plane.

[0182] This is due to Ag ions present on the (222) plane being reduced to Ag metal and escaping to the outside of the solid electrolyte.

[0183] Thermodynamic structural stability prediction results show that Ag ions are stable as Ag metal at 1.5–1.6 V. Therefore, at 1.2 V, Ag ions are stable as Ag and are reduced to Ag metal.

[0185] Figure 6 shows the OCV (open-circuit voltage) and Li at 1.2V before and after the discharge process. 5.4 Ag 0.6 These are the measurement results of the ionic conductivity and electronic conductivity of PS5Cl.

[0186] A 1.2V discharge refers to the voltage at which Ag metal is formed.

[0187] The ionic conductivity was maintained at 1.0 mS / cm in the state where Ag metal was precipitated.

[0188] And 1.5 e at OCV -10 The electron conductivity, which was measured in S / cm, became 2.5 e simultaneously with the formation of Ag. -3 It increased significantly to S / cm.

[0189] This is because the electrochemically formed Ag continuously forms channels that provide electron conductivity. This means that during the discharge process, the insulating solid electrolyte is converted into a solid electrolyte with high electron conductivity through electrochemical reactions.

[0191] Figure 7 shows the cross-sectional SEM image results at OCV (open-circuit voltage) (a) and 0V discharge state (b).

[0192] Cross-sectional SEM confirmed that Ag is formed in the solid electrolyte containing Ag during the discharge process.

[0193] First of all, Li6PS5Cl 0.5 Br 0.5 The solid electrolyte layer of and Li 5.4 Ag 0.6 A double layer was fabricated using PS5Cl.

[0194] Before discharge, no metallic components were detected in the solid electrolyte containing Ag, and only the solid electrolyte was observed.

[0195] Li in a state discharged to 0V 5.4 Ag 0.6 In the PS5Cl layer, it can be confirmed that Ag metal has formed along the grain boundaries.

[0197] Fig. 8 is SUS / Li 6-x Ag x PS5Cl / Li6PS5Cl 0.5 Br 0.5 This is the result of the evaluation of the reversibility of Li deposition on the / Li half-paper.

[0198] By applying Li6PS5Cl containing Ag, the reversibility of Li deposition was evaluated by fabricating a double layer using heterogeneous solid electrolytes containing and not containing Ag.

[0199] The battery composition is SUS / Li 6-x Ag x PS5Cl / Li6PS5Cl 0.5 Br 0.5 / Li is.

[0200] The results of the lithium deposition and desorption evaluation on SUS are presented.

[0201] A negative electrode all-solid-state battery was manufactured using a solid electrolyte containing Ag.

[0202] The battery manufacturing method is as follows.

[0203] 150 mg Li6PS5Cl in a 13 mm mold with insulating properties 0.5 Br 0.5 Insert and pressurize at 50 MPa. Then, / Li having a thickness of 15 μm 6-x Ag x After inserting the PS5Cl electrode, pressurize it to 500 MPa. Then, insert a Li metal film on the opposite side and pressurize it to 20 MPa.

[0204] The current density is 1.0 mA cm⁻¹ -1 and the deposition capacity is 1.0 mAh cm⁻¹. -1 am.

[0205] As the proportion of Ag increased, reversibility increased, and Ag 0.6 In terms of composition, stable operation was possible for more than 1,000 cycles.

[0206] However, when only Li6PS5Cl was used, a short circuit occurred within 2 cycles, and abnormal efficiency per cycle was confirmed.

[0207] This result implies that the formation of Ag metal during the battery operation process is directly related to the reversibility of lithium deposition.

[0209] Fig. 9 is SUS / Li5.4 Ag 0.6 PS5Cl / Li6PS5Cl 0.5 Br 0.5 This is the cycle graph of the / Li half-cell.

[0210] Figure 9 is Ag 0.6 Shows a cycle graph for 1,000 cycles when a solid electrolyte containing the composition is applied.

[0211] Even when the electrochemical deposition and desorption process of lithium metal was repeated up to 1,000 times, deposition and desorption were confirmed at a constant voltage.

[0212] This demonstrates that lithium is deposited based on very high reversibility, and that the battery's resistance does not increase during the charge-discharge process.

[0214] Figure 10 shows the anode / Li6PS5Cl 0.5 Br 0.5 / Li 5.4 Ag 0.6 This is the evaluation result of the PS5Cl / SUS pouch-type cathode-free complete paper.

[0215] Li6PS5Cl to manufacture complete paper 0.5 Br 0.5 After slurry coating and drying at 30㎛, Li 5.4 Ag 0.6 A double layer was prepared by coating PS5Cl to a thickness of 15 μm.

[0216] The positive electrode is LiNi 0.8 Co 0.1 Mn 0.1 An electrode was prepared by preparing a slurry and coating O2, Li6P5Cl solid electrolyte, carbon conductive material, and rubber binder in a weight ratio of 80:17:1.5:1.5.

[0217] Afterwards, the anode, double layer, and SUS layer were stacked sequentially, and after pouch sealing, the WIP process was performed at 500 MPa for 5 minutes. The cell evaluation pressure is 2.0 MPa.

[0218] As a result of cell evaluation at 0.1C, the initial discharge capacity was measured to be approximately 210mAh / g, which is 7.0mAh cm⁻¹.-2 It was confirmed that the cell operates stably for 50 cycles with a very high capacity.

[0219] This suggests that applying a solid electrolyte double layer containing an Ag-containing solid electrolyte is a key mechanism capable of inducing uniform lithium deposition.

[0221] Fig. 11 is SUS / Li 5.1 Ag 0.9 PS5Cl / Li6PS5Cl 0.5 Br 0.5 This is the graph of the first cycle of the / Li half-battery. When discharged from an open-circuit voltage of 2.6 V, the capacitance was developed at around 1.8 V.

[0222] This means the precipitation reaction of Ag.

[0223] It was confirmed that the deposited lithium reversibly returns during charging.

[0225] Fig. 12 is SUS / Li 5.1 Ag 0.9 PS5Cl / Li6PS5Cl 0.5 Br 0.5 This is the result of evaluating the reversibility of Li deposition on the / Li half-cell, and the lithium deposition and desorption reactions were driven for more than 50 cycles.

[0226] The efficiency per cycle is 99%, and reversible lithium deposition was confirmed even at high silver content.

[0228] Accordingly, the present invention can manufacture a cathode-free battery by introducing a solid electrolyte double layer and configuring it with an anode / solid electrolyte double layer / negative current collector, and can significantly improve the reversibility of the battery.

[0229] In particular, by selectively precipitating silver (Ag) through an electrochemical reduction reaction in a solid electrolyte containing heterogeneous cations, ion and electron transport pathways are formed, thereby maintaining lithium ion conductivity and further enhancing electron conductivity.

[0230] In addition, uniform lithium deposition can be induced through the application of a double layer of solid electrolyte.

[0232] Although the present invention has been described above with reference to the illustrated drawings, the present invention is not limited by the embodiments and drawings disclosed in this specification, and it is obvious that various modifications can be made by a person skilled in the art within the scope of the technical concept of the present invention. Furthermore, even if the effects of the configuration according to the present invention were not explicitly described while explaining the embodiments of the present invention above, it is natural to acknowledge that the effects predictable by said configuration should also be recognized. Explanation of the symbols

[0234] 10: Cathode current collector 20: First solid electrolyte layer 30: Second solid electrolyte layer 40 : Anode

Claims

Claim 1 It comprises a negative electrode current collector; a first solid electrolyte layer doped with silver (Ag) located on the negative electrode current collector; a second solid electrolyte layer located on the first solid electrolyte layer; and an anode located on the second solid electrolyte layer; wherein the electron conductivity at a discharge voltage of 1.2V is 1.0 × 10⁻⁶ -3 A non-anode all-solid-state battery having a S / cm or greater, and when analyzing the XRD diffraction pattern of the non-anode all-solid-state battery at a discharge voltage of 1.2V, the intensity of the peak of the (311) plane is greater than the intensity of the peak of the (222) plane. Claim 2 A non-anode all-solid-state battery according to claim 1, wherein the ion conductivity at a discharge voltage of 1.2V is 1.0mS / cm or higher. Claim 3 A non-cathode all-solid-state battery according to claim 1, wherein when analyzing the XRD diffraction pattern of the non-cathode all-solid-state battery at an open-circuit voltage of 2.3V, the intensity of the peak of the (222) plane is greater than the intensity of the peak of the (311) plane. Claim 4 A non-anode all-solid-state battery according to claim 1, wherein the silver (Ag)-doped first solid electrolyte layer comprises silver (Ag) metal that is reduced and precipitated from silver (Ag) ions during charging and discharging. Claim 5 In claim 1, the first solid electrolyte layer doped with silver (Ag) during charging and discharging has an argyrodite-type crystal structure and is a non-anode all-solid-state battery. Claim 6 In claim 1, the silver (Ag)-doped first solid electrolyte layer is Li a-b Ag b P c S d X e A non-anode all-solid-state battery comprising (wherein X comprises one or more of F, Cl, Br, and I, and 0 <a≤15, 0.2≤b≤0.6, 0≤c≤3, 0<d≤12, 0≤e≤3이다.) Claim 7 In claim 1, the second solid electrolyte layer is Li a P c S d X e A non-anode all-solid-state battery comprising (wherein X comprises one or more of F, Cl, Br, and I, and 0 <a≤15, 0≤c≤3, 0<d≤12, 0≤e≤3이다.) Claim 8 A non-anode all-solid-state battery according to claim 1, wherein the thickness of the silver (Ag)-doped first solid electrolyte layer is 10 nm to 100 µm. Claim 9 In claim 1, the positive electrode comprises a positive current collector and a positive material disposed on at least one surface of the positive current collector, in a non-negative all-solid-state battery. Claim 10 In claim 9, the above-mentioned cathode material comprises one or more cathode active materials selected from lithium cobalt oxide, lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide, lithium nickel cobalt manganese oxide, lithium manganese oxide, and lithium iron phosphate oxide, thereby forming a non-anode all-solid-state battery. Claim 11 delete

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