Method for electrodepositing electroactive species at solid-solid interfaces

Abstract

This disclosure describes an electrodeposition method using pulsed current to improve the uniformity of electrodeposits at solid-solid interfaces. It has been demonstrated that robust electrodeposited metal films can be deposited at solid-solid interfaces without damaging the solid electrolyte. Furthermore, the effects of pulse parameters, including current density, pulse width, and duty cycle, have been shown to significantly affect the spatial distribution of the electrodeposited metal. This methodology can support the fabrication of thin films and microstructures for applications in advanced functional materials and electrochemical devices. In one embodiment, this method enables anode-free fabrication, where a battery is fabricated in a discharged state by replacing a conventional anode with a bare current collector, and then electrochemically forming a metal anode during the first charge cycle by electroplating the metal contained within the cathode.

Description

[Technical Field]

[0001] <Cross-reference of related applications> This application is based on U.S. Patent Application No. 62 / 963,700, filed on 21 January 2020, and U.S. Patent Application No. 62 / 988,986, filed on 13 March 2020, claiming priority thereto, which are incorporated in their entirety by reference to this specification for all purposes.

[0002] <Statement regarding research supported by the federal government> This invention was made with government support under ruling DE-AR0000653 by the U.S. Department of Energy. The government has certain rights in this invention.

[0003] The present invention relates to a method for electrodepositing electroactive species onto a solid to achieve a uniform film of electrodeposited material using a pulsed current electrodeposition process. More specifically, the present invention relates to anode-free manufacturing, in which a battery is manufactured in a discharged state by replacing the conventional anode with a bare current collector, and then a metal anode is electrochemically formed in the first charging cycle by electroplating a metal contained in the cathode. [Background technology]

[0004] Methods for electrochemically depositing electroactive species onto substrates are widely used in the controlled fabrication of microstructures and in surface engineering. In conventional electrodeposition, electroactive species, generally metal cations, are contained in a liquid electrolyte and bonded to the working electrode and counter electrode. When a potential is supplied to the electrodes, an electrochemical reaction occurs at the working electrode / electrolyte interface, and the metal cation is deposited on the working electrode as pure metal. Because this technique can be used to attach thin metal films or microstructures to surfaces, various methods have been developed to more precisely control the morphology of the electrodeposited metal. These techniques generally involve adjusting factors such as electrolyte composition, surface chemistry, and electrochemical reaction rate to deposit metals with the desired microstructure [References 1-5]. However, considering the fundamentally different properties of solid and liquid electrolytes, the electrodeposition mechanism differs significantly at the solid-solid interface [References 6-10]. When electroactive species precipitate and begin nucleating at the working electrode / electrolyte interface, the working electrode and electrolyte are forcibly separated, and a new solid phase grows between them. For oxidation-reduction reactions to occur, contact must be maintained to supply electrons. Therefore, achieving a uniform electrodeposited film requires a complex balance of factors such as nucleus growth rate, surface tension and diffusivity at multiple interfaces, and the mechanical properties of various components. With the advancement of solid electrolyte development aimed at applications in batteries and fuel cells, electrodeposition at solid-solid interfaces is becoming increasingly important. Consequently, methods for controlling the electrodeposition rate and dynamics at solid-solid interfaces are necessary to control the microstructure of electrodeposited films at these interfaces. Some applications, such as solid-state memory devices, require sharp, dendritic structures, while other applications, such as energy storage, require dense, conformal films. [Overview of the project]

[0005] Therefore, improved methods are needed to electrodeposit electroactive materials onto solid substrates or solid electrolytes to achieve desired configurations.

[0006] The microstructure of electrodeposited materials, generally metallic, is influenced by factors such as the concentration gradient in the electrolyte, surface chemistry and morphology, and electrochemical reaction rates. Conventional electrochemical systems using liquid electrolytes have various techniques that can be used to adjust these factors and enable precise control of the precipitate microstructure. However, with solid electrolytes, the mechanical and chemical environment surrounding the electrode / electrolyte interface is fundamentally different, and therefore the mechanisms governing the microstructure of the electroplated material can be significantly different. Thus, when the electrolyte is solid rather than liquid, the methods for controlling the microstructure of the electroplated material are different. In many applications, a uniform electrodeposited film is a highly desirable form. This disclosure discloses a methodology for achieving a uniform electrodeposited film at the interface between a solid electrode and a solid electrolyte using a pulsed current electrodeposition process.

[0007] Whether a metal substrate and a solid electrolyte can adapt to the volume expansion associated with electrodeposition at the interface depends on the mechanical properties of the individual components, such as the solid electrolyte, electroactive species, and metal substrate, as well as the interfacial properties, such as microstructure, adhesion, and electrochemical reaction rate. This disclosure provides a method for electrodepositing electroactive species onto a solid current collector coated with a solid electrolyte by contacting a solid electrolyte material with an electrode to form a layered structure and passing an electric current through the layered structure. The current collector may be a metal, metal alloy, or conductive composite (e.g., polymer-metal composite or metal-metal oxide composite) that is nonreactive with the electroactive species and bonded to the solid electrolyte by diffusion bonding, evaporation process, sintering, or mechanical pressure, and may have a thickness of 100 nm to 1 mm. The electrode may include a metal, metal alloy, or any compound containing an electroactive species. The electrodeposition process depletes the electroactive species from the electrode and has a current of 1 μA / cm 2 ~1mA / cm 2 This is done by using an electric current to deposit the material onto the current collector.

[0008] On one side, the present disclosure provides a method for manufacturing an electrochemical device. The method includes: (a) preparing a current collector coated with a solid electrolyte material; (b) contacting the solid electrolyte material with an electrode containing electroactive species to form a layered structure; (c) applying a pressure greater than 0 MPa to the layered structure; and (d) passing a current through the layered structure using a series of pulse cycles to form an interfacial layer containing electroactive species between the solid electrolyte material and the current collector, wherein the interfacial layer functions as the anode of the electrochemical device and the electrode functions as the cathode of the electrochemical device. In one embodiment of the method, step (c) includes applying a pressure of 0.1 MPa to 100 MPa to the layered structure. In one embodiment of the method, step (c) includes applying a pressure of 1 MPa to 10 MPa to the layered structure.

[0009] In this method, each pulse cycle may include: (i) supplying an on-current for a given pulse width; and (ii) supplying an off-current for a certain length of time based on the duty cycle and the pulse width, where the off-current has a first current density value smaller than a second current density value of the on-current. The on-current can be a direct current in the range of 1 μA / cm 2 ~1 A / cm 2 . The on-current can be a direct current in the range of 0.01 mA / cm 2 ~1 mA / cm 2 . The current can be a direct current in the range of 1 μA / cm 2 ~1 mA / cm 2 . The pulse width can be from 1 μs to 100 s. The pulse width can be from 1 s to 10 s. The off-current can be a direct current in the range of -1 A / cm 2 ~0.9 μA / cm 2 . The duty cycle can be from 0.1% to 99%. The duty cycle can be from 50% to 99%. The duty cycle can be from 70% to 99%. The duty cycle can be from 80% to 99%.

[0010] In one embodiment of the method, step (d) further includes monitoring the propagation of an electroactive species from the anode to the solid electrolyte while an electric current is passed through the layered structure using a series of pulse cycles, wherein each pulse cycle includes (i) supplying an on-current for a given pulse width and (ii) supplying an off-current for a certain length of time based on the duty cycle and pulse width, and step (d) further includes varying at least one of (i) pulse width, (ii) a certain length of time, (iii) duty cycle, (iv) a first current density value of the off-current, and (iv) a second current density value of the on-current, when the prediction of the propagation of an electroactive species from the anode to the solid electrolyte is performed by monitoring.

[0011] In one embodiment of this method, the current collector comprises a single material consisting of a metal or a metal alloy. The current collector may also comprise a material selected from the group consisting of nickel, molybdenum, titanium, zirconium, tantalum, alloy steel, stainless steel, nickel-based superalloy, cobalt-based superalloy, copper, aluminum, iron, or mixtures thereof. The current collector may have a thickness of 1 nm to 100 μm.

[0012] In one embodiment of this method, the solid electrolyte material includes a material selected from the group consisting of lithium oxynitride phosphate (LiPON), oxide garnet, sodium superionic conductor (NaSICON), lithium superionic conductor (LiSICON), thioLiSICON, sulfide glass, polymer, or mixtures thereof. In one embodiment of this method, the solid electrolyte material is selected from the group consisting of lithium lanthanum zirconium oxide (LLZO), aluminum-doped LLZO, gallium-doped LLZO, niobium-doped LLZO, tantalum-doped LLZO, lithium aluminum titanium phosphate (LATP), lithium aluminum germanium phosphate (LAGP), lithium phosphorus sulfide (LPS), poly(ethylene oxide) (PEO), polyacrylonitrile (PAN), crystalline thermoplastic polymer, alkali metal cation alumina, metal halide, or mixtures thereof. The solid electrolyte material may include lithium lanthanum zirconium oxide (LLZO) or its derivatives. In one embodiment of this method, the solid electrolyte material is Li w A x M2Re 3-y O z It includes a ceramic material having the chemical formula, in which, w is 5-7.5, A is selected from B, Al, Ga, In, Zn, Cd, Y, Sc, Mg, Ca, Sr, Ba, and any combination thereof. x ranges from 0 to 2. M is selected from Zr, Hf, Nb, Ta, Mo, W, Sn, Ge, Si, Sb, Se, Te, and any combination thereof. Re is selected from lanthanide elements, actinide elements, and any combination thereof. y is between 0 and 0.75. z is between 10.875 and 13.125. Ceramic materials have a garnet-type or garnet-like crystalline structure. In one embodiment of the ceramic material, M is a combination of Zr and Ta. In one embodiment of the ceramic material, M is Zr, A is Al, and x is not 0. In one embodiment of the ceramic material, M is Zr, A is Ga, and x is not 0. In one embodiment of the method, the solid electrolyte material comprises sodium β-alumina and / or sodium β''-alumina.

[0013] In one embodiment of this method, the solid electrolyte material is coated onto the current collector using at least one of the following methods: diffusion bonding, chemical vapor deposition, physical vapor deposition, atomic layer deposition, slurry casting sintering, slurry casting hot pressing, painting, powder coating, thermal spraying, low-temperature thermal spraying, aerosol deposition, flux deposition, electrodeposition, electroless chemical deposition, or a combination thereof. The solid electrolyte material can have a thickness of 1 nm to 100 μm.

[0014] In one embodiment of this method, the interface layer has a thickness of 1 nm to 100 μm.

[0015] In one embodiment of this method, the current collector electrochemically blocks electroactive species. In one embodiment of this method, the current collector comprises a bimetal having a first layer made of a first metallic material and a second layer made of a second metallic material, wherein the first layer is at least partially in contact with the solid electrolyte material before step (d), and the second layer is in contact with the first layer. The first metallic material can electrochemically block electroactive species. The first metallic material can be selected from the group consisting of nickel, molybdenum, titanium, zirconium, tantalum, nickel-based superalloys, cobalt-based superalloys, copper, or mixtures thereof, and the second material can be selected from the group consisting of aluminum, nickel, alloy steel, stainless steel, nickel-based superalloys, or mixtures thereof. The first metallic material may be made of nickel, and the second material may be made of stainless steel. The first layer may have a thickness of 1 nm to 100 μm, and the second layer may have a thickness of 1 nm to 100 μm.

[0016] In one embodiment of this method, the electrode comprises a single material consisting of a metal or a metal alloy. The electrode may include a material selected from the group consisting of lithium, sodium, silver, magnesium, calcium, cobalt, iron, potassium, copper, or mixtures thereof. The electrode may also include lithium.

[0017] In one embodiment of this method, the electrode comprises a lithium host material selected from the group consisting of (i) LiC6, (ii) lithium metal oxides in which the metal is one or more aluminum, cobalt, iron, manganese, nickel, and vanadium, and (iii) lithium-containing phosphates having the general chemical formula LiMPO4, where M is one or more of cobalt, iron, manganese, and nickel. The electrode may further comprise a binder and a conductive additive. The binder may include a polymer material, and the conductive additive may include a carbon compound. The electrode may be a conductive composite material containing electroactive species.

[0018] In one embodiment of the present method, step (b) includes evaporating a first layer of lithium on a solid electrolyte material, and then pressing a lithium foil onto the first layer such that the electrode consists of the first layer of lithium and a lithium foil.

[0019] In one embodiment of this method, step (c) includes applying pressure to the layered structure at a temperature of 25°C to 180°C.

[0020] In one embodiment of this method, no damage occurs to the solid electrolyte material during step (d). In one embodiment of this method, no penetration of dendritic crystals into the solid electrolyte material occurs during step (d).

[0021] In one embodiment of this method, the interface layer has a uniform thickness after step (d). In one embodiment of this method, the interface layer has a surface coverage of 5% or more with respect to the solid electrolyte after step (d). The interface layer may have a surface coverage of 70% or more with respect to the solid electrolyte after step (d). The interface layer may be in complete surface contact with the solid electrolyte material after step (d).

[0022] In one embodiment of this method, the current collector coated with the solid electrolyte material prepared in step (a) has a porosity of 0.1% to 99% at the interface between the current collector and the solid electrolyte material. In one embodiment of this method, the current collector coated with the solid electrolyte material prepared in step (a) has a porosity of 0.1% to 10% at the interface between the current collector and the solid electrolyte material.

[0023] In one embodiment of this method, the interfacial resistance between the current collector and the solid electrolyte material prepared in step (a) is 10,000 Ωcm. 2 It is less than 1000 Ωcm. The interfacial resistance between the current collector and the solid electrolyte material prepared in step (a) is 1000 Ωcm. 2 It may be less than.

[0024] In one embodiment of this method, the interfacial resistance between the interfacial layer and the solid electrolyte after step (d) is 100 Ωcm. 2 It is less than . The interfacial resistance between the interfacial layer and the solid electrolyte after step (d) is 25 Ωcm 2 It may be less than.

[0025] In one embodiment of this method, the RMS surface roughness of the solid electrolyte material coated with the current collector is 5 μm or less. The RMS surface roughness of the solid electrolyte material coated with the current collector may be 500 nm or less.

[0026] In one embodiment of this method, the interface layer has a density such that the anode exhibits non-blocking behavior with respect to electroactive species. In one embodiment of this method, after step (d), the interface layer does not show dendritic crystal formation.

[0027] In another aspect, the present disclosure provides a method for manufacturing an electrochemical device. The method may include the steps of (a) preparing a current collector coated with a solid electrolyte material comprising a doped lithium lanthanum zirconium oxide; (b) contacting the solid electrolyte material with an electrode comprising an electroactive species to form a layered structure; and (c) passing an electric current through the layered structure using a series of pulse cycles to form an interface layer comprising an electroactive species between the solid electrolyte material and the current collector, wherein the interface layer functions as the anode of an electrochemical device and the electrode functions as the cathode of an electrochemical device.

[0028] In one embodiment of this method, the solid electrolyte material includes aluminum-doped lithium lanthanum-zirconium oxide, or gallium-doped lithium lanthanum-zirconium oxide, or niobium-doped lithium lanthanum-zirconium oxide, or tantalum-doped lithium lanthanum-zirconium oxide. In one embodiment of this method, the solid electrolyte material is Li w A x M2Re 3-y O z It includes a ceramic material having the chemical formula, in which, w is 5-7.5, A is selected from B, Al, Ga, In, Zn, Cd, Y, Sc, Mg, Ca, Sr, Ba, and any combination thereof. x ranges from 0 to 2. M is selected from Zr, Hf, Nb, Ta, Mo, W, Sn, Ge, Si, Sb, Se, Te, and any combination thereof. Re is selected from lanthanide elements, actinide elements, and any combination thereof. y is between 0 and 0.75. z is between 10.875 and 13.125. Ceramic materials have a garnet-type or garnet-like crystalline structure. In one embodiment of the ceramic material, M is a combination of Zr and Ta. In one embodiment of the ceramic material, M is Zr, A is Al, and x is not 0. In one embodiment of the ceramic material, M is Zr, A is Ga, and x is not 0.

[0029] In one embodiment of this method, step (c) further includes applying a pressure greater than 0 MPa to the layered structure. In one embodiment of this method, the pressure is between 0.1 MPa and 100 MPa. In one embodiment of this method, the pressure is between 1 MPa and 10 MPa.

[0030] In another aspect, the present disclosure provides a method for manufacturing an electrochemical device. The method may include (a) preparing a current collector coated with a solid electrolyte material, (b) contacting the solid electrolyte material with an electrode containing an electroactive species to form a layered structure, and (c) passing an electric current through the layered structure using a series of pulse cycles to form an interface layer containing an electroactive species between the solid electrolyte material and the current collector, wherein the interface layer functions as the anode of the electrochemical device, the electrode functions as the cathode of the electrochemical device, and the solid electrolyte material is Li w A x M2Re 3-y O z It includes a ceramic material having the chemical formula, in which, w is 5-7.5, A is selected from B, Al, Ga, In, Zn, Cd, Y, Sc, Mg, Ca, Sr, Ba, and any combination thereof. x ranges from 0 to 2. M is selected from Zr, Hf, Nb, Ta, Mo, W, Sn, Ge, Si, Sb, Se, Te, and any combination thereof. Re is selected from lanthanide elements, actinide elements, and any combination thereof. y is between 0 and 0.75. z is between 10.875 and 13.125. Here, the ceramic material has a garnet-type or garnet-like crystal structure. When x is 0, M is two or more of the following: Zr, Hf, Nb, Ta, Mo, W, Sn, Ge, Si, Sb, Se, and Te. In one embodiment of the ceramic material, Re is lanthanum. In one embodiment of the ceramic material, M is a combination of Zr and Ta. In one embodiment of the ceramic material, M is Zr, A is Al, and x is not 0. In one embodiment of the ceramic material, M is Zr, A is Ga, and x is not 0. The solid electrolyte is Li 6.5 La3Zr 1.5 Ta 0.5 O 12 It can include...

[0031] In one embodiment of this method, step (c) further includes applying a pressure greater than 0 MPa to the layered structure. In one embodiment of this method, the pressure is between 0.1 MPa and 100 MPa. In one embodiment of this method, the pressure is between 1 MPa and 10 MPa.

[0032] The above and other features, aspects and advantages of the present disclosure will be better understood by considering the following detailed description, drawings and appended claims. [Brief explanation of the drawing]

[0033] [Figure 1] A schematic diagram of a lithium metal battery is shown. [Figure 1A] This is an illustrative schematic diagram of a pulsed current electroplating profile and pulse parameters. [Figure 2A] This is an exemplary electrochemical characterization of the DC potential response during lithium electrodeposition according to one embodiment of the present invention. [Figure 2B] This is an exemplary electrochemical characteristic evaluation of the AC impedance of an electrochemical cell before and after lithium electrodeposition, according to one embodiment of the disclosure of this application. [Figure 3]Panel a) shows an image of lithium electrodeposited on LLZO after the nickel substrate has been removed, clearly showing metallic (lithium) and nonmetallic (LLZO) regions as a result of the non-uniform deposition of lithium; Panel b) shows an exemplary electrodeposited lithium morphology for a 100% duty cycle (DC current) according to one embodiment of the disclosure; Panel c) shows an exemplary electrodeposited lithium morphology for an 80% duty cycle and low current density according to one embodiment of the disclosure; Panel d) shows an exemplary electrodeposited lithium morphology for an 80% duty cycle and high current density according to one embodiment of the disclosure; and Panel e) shows an exemplary electrodeposited lithium morphology in which a considerable amount of lithium has been deposited, exceeding the thickness of the nickel substrate, according to one embodiment of the disclosure. [Figure 4A] This shows a SEM-FIB cross-sectional analysis of the interface between the LLZO and the current collector, taken during assembly. [Figure 4B] This image shows a SEM-FIB cross-sectional analysis of the interface between LLZO and the current collector, taken after Li plating at 5 mAh / cm2. Although metallic Li is observed between the Cu and LLZO layers as secondary electrons, it cannot be detected because the characteristic X-ray energy is outside the detection range of the EDS. [Figure 4C] This shows a SEM-FIB cross-sectional analysis of the interface between LLZO and the current collector, obtained after Li plating at 5 mAh / cm2 and then stripping the plating. [Figure 4D] This shows a SEM-FIB cross-sectional analysis of the interface between LLZO and the current collector, and an elemental map of Cu and Zr at the interface during assembly. [Figure 4E] This shows a SEM-FIB cross-sectional analysis of the interface between LLZO and the current collector, and an elemental map of Cu and Zr at the interface after plating. [Figure 4F] This shows the SEM-FIB cross-sectional analysis of the interface between LLZO and the current collector, and the elemental maps of Cu and Zr at the interface after plating and stripping. [Figure 5]The images from Figure 4 show low-magnification SEM of FIB-milled cross-sections. Panel (a) shows copper current collectors laminated on LLZO, panel (b) shows them after Li plating at 5 mAh / cm², and panel (c) shows them after Li plating at 5 mAh / cm² and subsequent stripping. The intermediate Li layer between Cu and LLZO in panel (b) shows clearer structural features at low magnification, indicating the presence of an intermediate phase rather than voids, despite the high color contrast. At the interface after stripping the Li plating at 5 mAh / cm², Cu and LLZO do not separate significantly in all areas, as observed in panel (c). One such area where the separation is less pronounced is shown in panel (d). This indicates a small gap between Cu and LLZO, but it is still more pronounced than in panel (a), and similar residue between Cu and LLZO is seen, as observed in panel (c). [Modes for carrying out the invention]

[0034] Before describing the present invention in detail, it should be understood that the present invention is not limited to the specific embodiments described herein. Furthermore, the terminology used herein is intended solely to describe specific embodiments and is not intended to limit the present invention. The scope of the present invention is limited only by the claims. The singular forms "a, an" and "the" used herein include multiple embodiments unless otherwise evident from the context.

[0035] Those skilled in the art will see that, in addition to the aspects already described, many other improvements to the present invention are possible without departing from the spirit of the invention. In interpreting the present disclosure, all terms should be interpreted in the broadest possible sense in the context. Variations of the terms “equipment,” “includes,” or “have” should be interpreted as referring non-exclusively to elements, parts, or steps, so that the elements, parts, or steps referred to may be combined with other elements, parts, or steps not explicitly mentioned. Embodiments described as “equipment,” “includes,” or “have” a particular element should, unless the context makes it clear, include both the meaning of “substantially consisting” of that element and the meaning of “consisting of” that element. Unless the context makes it clear, aspects of the present disclosure relating to a system should be interpreted as also applying to a method, and vice versa.

[0036] In this context, "cell" or "electrochemical cell" refers to a basic electrochemical unit equipped with electrodes and an electrolyte. Unless otherwise specified in the context, "electrochemical cell" here refers to a rechargeable cell, also known as a "secondary battery." In an electrochemical cell or electrochemical device, the "anode" is defined as the electrode that loses electrons through oxidation during discharge. The "cathode" is defined as the electrode that gains electrons through reduction during discharge. These electrochemical roles are reversed during the charging process in an electrochemical cell or electrochemical device, but the electrode names "anode" and "cathode" remain unchanged.

[0037] Here, "uniform thickness" means that the thickness non-uniformity from one end to the other of an element (e.g., a layer) is ±25% or less. For example, if a layer has a minimum thickness of 100-25 and a maximum thickness of 100+25 from one end to the other, the thickness non-uniformity is ±25%.

[0038] The numerical ranges disclosed herein include both ends. For example, the numerical range 1 to 10 includes the values ​​1 and 10. Where multiple consecutive numerical ranges are disclosed for a particular value, the disclosure expressly assumes a range that includes all combinations of the upper and lower limits of each of these multiple numerical ranges. For example, the numerical range 1 to 10 or the numerical range 2 to 9 is intended to include the numerical range 1 to 9 and the numerical range 2 to 10.

[0039] One embodiment of the method of the present invention enables anode-free manufacturing, in which a battery is manufactured in a discharged state by replacing the conventional anode with a bare current collector, and then a metal anode is electrochemically formed in the first charging cycle by electroplating a metal contained in the cathode. Figure 1 shows a non-limiting example of a lithium metal battery 110 that can be manufactured using embodiments of the present disclosure. The lithium metal battery 110 of Figure 1 includes a first current collector 112 (i.e., aluminum) in contact with the cathode 114. A solid electrolyte 116 is placed between the cathode 114 and the anode 120, and the anode is in contact with a second current collector 122 (i.e., copper). The first current collector 112 and the second current collector 122 of the lithium metal battery 110 may be electrically connected to an electrical component 124. The electrical component 124 can electrically connect the lithium metal battery 110 to an electrical load that discharges the battery or a charger that charges the battery.

[0040] The first current collector 112 and the second current collector 122 may include a conductive metal or any suitable conductive material. In some embodiments, the first current collector 112 and the second current collector 122 may be a single material consisting of a metal or a metal alloy. In the case of a single material, the first current collector 112 and the second current collector 122 may include materials selected from the group consisting of nickel, molybdenum, titanium, zirconium, tantalum, alloy steel, stainless steel, nickel-based superalloy (e.g., Inconel), cobalt-based superalloy, copper, aluminum, or mixtures, combinations, and alloys thereof. In some embodiments, the first current collector 112 and the second current collector 122 may have a thickness of 1 nm to 100 μm, 10 nm to 60 μm, or 900 nm to 25 μm. Please note that the thicknesses shown in Figure 1 are not drawn to scale. Furthermore, please note that the thicknesses of the first current collector 112 and the second current collector 122 may differ.

[0041] In some embodiments, a suitable cathode 114 of a lithium metal battery 110 is a lithium host material capable of storing and subsequently releasing lithium ions. Exemplary cathode active materials are lithium metal oxides, where the metal is one or more aluminum, cobalt, iron, manganese, nickel, and vanadium. Non-limiting examples of lithium metal oxides include LiCoO2 (LCO), LiFeO2, LiMnO2 (LMO), LiMn2O4, LiNiO2 (LNO), and LiNi x Co y O2, LiMn x Co y O2, LiMn x Ni y O2, LiMn x Ni y O4, LiSa x Co y Al z O2(NCA), LiNi 1 / 3 Mn 1 / 3 Co 1 / 3Examples include O2. Another exemplary cathode active material is a lithium-containing phosphate having the general chemical formula LiMPO4, such as lithium iron phosphate (LFP) and lithium iron fluorophosphate, where M is one or more of cobalt, iron, manganese, and nickel. Another exemplary cathode active material is LiNi x Mn y Co z The cathode active material has the chemical formula O2, where x+y+z=1 and x:y:z=1:1:1 (NMC111), x:y:z=4:3:3 (NMC433), x:y:z=5:2:2 (NMC522), x:y:z=5:3:2 (NMC532), x:y:z=6:2:2 (NMC622), or x:y:z=8:1:1 (NMC811). Many different elements, such as Co, Mn, Ni, Cr, Al, or Li, may be substituted or added to the structure to affect the electronic conductivity, layer order, delithiation stability, and cycling performance of the cathode material. The cathode active material can be a mixture of any number of these cathode active materials. Another exemplary cathode active material is LiC6. In other embodiments, suitable materials for the cathode 114 of the lithium metal battery 110 are porous carbon (for lithium-air batteries) or sulfur-containing materials (for lithium-sulfur batteries). The cathode 114 may have a thickness of 1 nm to 100 μm, 10 nm to 50 μm, or 100 nm to 10 μm.

[0042] In some embodiments, a suitable anode 120 of the lithium metal battery 110 consists of in-situ formed (e.g., electroplated) lithium metal. Another exemplary anode 120 material consists of essentially in-situ formed lithium metal. In other embodiments, a suitable anode 120 consists of in-situ formed magnesium, sodium, or zinc metal. In other embodiments, a suitable anode 120 consists of essentially in-situ formed magnesium, sodium, or zinc metal.

[0043] The material of the exemplary solid electrolyte 116 for the lithium metal battery 110 may include any suitable solid electrolyte capable of conducting metal ions. For example, the solid electrolyte may be lithium oxynitride phosphate (LiPON). The solid electrolyte may be an oxide garnet such as lithium lanthanum zirconium oxide (LLZO), aluminum-doped LLZO, gallium-doped LLZO, niobium-doped LLZO, or tantalum-doped LLZO. The solid electrolyte may be a sodium superionic conductor (NaSICON) such as lithium aluminum titanium phosphate (LATP). The solid electrolyte may be a lithium superionic conductor (LiSICON). The solid electrolyte may be thioLISICON. The solid electrolyte may be lithium aluminum germanium phosphate (LAGP). The solid electrolyte may be a sulfide glass such as lithium phosphorus sulfide (LPS). The solid electrolyte may be sodium β-alumina or sodium β'' alumina. The solid electrolyte may be a polymer such as polyethylene oxide (PEO), polyacrylonitrile (PAN), or crystalline thermoplastic polymer. The solid electrolyte may contain a mixture of any of the above electrolytes. The solid electrolyte may have a thickness of 1 nm to 100 μm, 100 nm to 50 μm, or 1 μm to 25 μm.

[0044] In another embodiment of the lithium metal battery 110, the solid electrolyte 116 for the lithium metal battery 110 is Li w A x M2Re 3-y O z It includes a ceramic material having the chemical formula, in which, w is 5-7.5, A is selected from B, Al, Ga, In, Zn, Cd, Y, Sc, Mg, Ca, Sr, Ba, and any combination thereof. x ranges from 0 to 2. M is selected from Zr, Hf, Nb, Ta, Mo, W, Sn, Ge, Si, Sb, Se, Te, and any combination thereof. Re is selected from lanthanide elements, actinide elements, and any combination thereof. y is between 0 and 0.75. z is between 10.875 and 13.125. Ceramic materials have a garnet-type or garnet-like crystalline structure. In some embodiments of the solid electrolyte 116, M is Zr, A is Al, and x is not 0, or M is Zr, A is Ga, and x is not 0, or M is a combination of Zr and Ta. In one embodiment, the solid electrolyte is Li 6.5 La3Zr 1.5 Ta 0.5 O 12 It consists of.

[0045] As part of a method for manufacturing an anode-free lithium metal battery 110, a method is disclosed for electrodepositing electroactive species from a solid electrolyte using a pulsed current method to form a uniform film at the solid substrate / solid electrolyte interface in a layered structure comprising a current collector coated with a solid electrolyte material that contacts electrodes containing electroactive species. The solid substrate may be the current collector 122 of the lithium metal battery 110. The current collector 122 can electrochemically block the electroactive species. The term "blocking" as used herein may refer to a current collector made of a material that can be considered non-reactive with the electroactive species, with a sufficiently low solubility of the electroactive species as determined by the thermodynamic phase diagram. The solid electrolyte may be the solid electrolyte 116 of the lithium metal battery 110. The electrodes may be the lithified cathode 114 of the lithium metal battery 110. The electroactive species may be lithium. The solid electrolyte material may be coated onto the current collector using any suitable bonding method. For example, coating a current collector with a solid electrolyte may be achieved using diffusion bonding, chemical vapor deposition, physical vapor deposition, atomic layer deposition, slurry casting sintering, slurry casting hot pressing, painting, powder coating, thermal spraying, low-temperature thermal spraying, aerosol deposition, flux deposition, electrodeposition, electroless chemical deposition, or a combination thereof.

[0046] Electrodeposition is performed on a layered structure using a periodic pulsed current method, which involves supplying a non-zero DC on-current for a given pulse width. An on-pulse is followed by an off-pulse at a lower current density for a certain length of time determined by the duty cycle. A series of on-pulses and off-pulses are then periodically repeated until a suitable mass of material is electroplated as the interface layer, e.g., anode 120. Because the governing mechanism of electrodeposition differs fundamentally between solid and liquid electrolytes, the control methods for achieving the desired microstructure differ in the solid systems disclosed herein. In the case of a solid substrate-solid electrolyte interface, the current density, pulse width, and duty cycle play important roles in controlling the distribution and number density of stable nuclei, the relaxation of internal stresses within the cell, and the delamination of the substrate and electrolyte. Therefore, by optimizing these parameters, the desired uniformity of the electroplated material constituting the interface layer (anode 120) between the current collector 122 and the solid electrolyte 116 can be achieved. Given the rigid constraint between the two solids, pulsed current is also advantageous for depositing material at the solid substrate / solid electrolyte interface without generating excessively large mechanical deformations that could lead to the destruction of surrounding components, such as the solid electrolyte 116.

[0047] While not intended to be theoretically bound, during the periodic pulsed current method of the present invention, the in-situ plated metal forming the interface layer constituting the anode 120 progresses from the formation of multiple isolated metal patches between the current collector 122 and the solid electrolyte 116, such that gaps exist in the interface layer, to the fusion of these metal patches, and finally to the formation of a metal interface layer of uniform thickness between the current collector 122 and the solid electrolyte 116, so that the interface layer can completely cover the surface with the solid electrolyte 116.

[0048] The thickness of the interface layer can have a non-uniformity of ±25% from one end to the other. The thickness of the interface layer can have a non-uniformity of ±20% from one end to the other. The thickness of the interface layer can have a non-uniformity of ±15% from one end to the other. The thickness of the interface layer can have a non-uniformity of ±10% from one end to the other. The thickness of the interface layer can have a non-uniformity of ±5% from one end to the other. The thickness of the interface layer can have a non-uniformity of ±2% from one end to the other.

[0049] The interface layer can have a surface coverage of 5% or more using a solid electrolyte. The interface layer can have a surface coverage of 70% or more using a solid electrolyte. The interface layer can have a surface coverage of 80% or more using a solid electrolyte. The interface layer can have a surface coverage of 85% or more using a solid electrolyte. The interface layer can have a surface coverage of 90% or more using a solid electrolyte. The interface layer can have a surface coverage of 95% or more using a solid electrolyte. The interface layer can have a surface coverage of 97% or more using a solid electrolyte. The interface layer can have a surface coverage of 98% or more using a solid electrolyte. The interface layer can have a surface coverage of 99% or more using a solid electrolyte.

[0050] In one embodiment of this method, a current collector coated with a solid electrolyte material can have a porosity of 0.1% to 99% at the interface between the current collector and the solid electrolyte material. In another embodiment of this method, a current collector coated with a solid electrolyte material can have a porosity of 0.1% to 90% at the interface between the current collector and the solid electrolyte material. In yet another embodiment of this method, a current collector coated with a solid electrolyte material can have a porosity of 0.1% to 70% at the interface between the current collector and the solid electrolyte material. In yet another embodiment of this method, a current collector coated with a solid electrolyte material can have a porosity of 0.1% to 50% at the interface between the current collector and the solid electrolyte material. In yet another embodiment of this method, a current collector coated with a solid electrolyte material can have a porosity of 0.1% to 30% at the interface between the current collector and the solid electrolyte material. In yet another embodiment of this method, a current collector coated with a solid electrolyte material can have a porosity of 0.1% to 10% at the interface between the current collector and the solid electrolyte material. In another embodiment of this method, a current collector coated with a solid electrolyte material may have a porosity of 0.1% to 5% at the interface between the current collector and the solid electrolyte material. In another embodiment of this method, a current collector coated with a solid electrolyte material may have a porosity of 0.1% to 2% at the interface between the current collector and the solid electrolyte material.

[0051] In this method, the interfacial resistance between the current collector and the solid electrolyte material is 10,000 Ωcm. 2 Less than 1000 Ωcm 2 Less than 500 Ωcm 2 Less than 450 Ωcm 2 Less than 400 Ωcm 2 Less than 350 Ωcm 2 Less than 300 Ωcm 2 Less than 250 Ωcm 2 Less than 200 Ωcm 2 Less than 150 Ωcm 2 Less than 100 Ωcm 2 Less than 75 Ωcm 2 Less than 50 Ωcm 2 Less than 25 Ωcm 2 Less than 10 Ωcm 2It may be less than.

[0052] This method can generate an interface layer having 0.1% to 99% surface contact with the solid electrolyte material, or 10% to 99% surface contact with the solid electrolyte material, or 50% to 99% surface contact with the solid electrolyte material, or 70% to 99% surface contact with the solid electrolyte material, or 80% to 99% surface contact with the solid electrolyte material, or 90% to 99% surface contact with the solid electrolyte material, or 95% to 99% surface contact with the solid electrolyte material.

[0053] In this method, the interfacial resistance obtained between the interfacial layer and the solid electrolyte is 1000 Ωcm. 2 Less than 500 Ωcm 2 Less than 450 Ωcm 2 Less than 400 Ωcm 2 Less than 350 Ωcm 2 Less than 300 Ωcm 2 Less than 250 Ωcm 2 Less than 200 Ωcm 2 Less than 150 Ωcm 2 Less than 100 Ωcm 2 Less than 75 Ωcm 2 Less than 50 Ωcm 2 Less than 25 Ωcm 2 Less than 10 Ωcm 2 It may be less than.

[0054] In this method, the RMS surface roughness of the solid electrolyte material may be 5 μm or less, 1 μm or less, 500 nm or less, 250 nm or less, 100 nm or less, or 50 nm or less.

[0055] As described above, in one aspect, the present disclosure provides a method for manufacturing an electrochemical device. The method may include (a) preparing a current collector coated with a solid electrolyte material, (b) contacting the solid electrolyte material with an electrode containing an electroactive species to form a layered structure, (c) applying a pressure greater than 0 MPa to the layered structure, and (d) passing an electric current through the layered structure using a series of pulse cycles to form an interface layer containing an electroactive species between the solid electrolyte material and the current collector. The interface layer functions as the anode of the electrochemical device, and the electrode functions as the cathode of the electrochemical device. After step (d), the interface layer may have a uniform thickness. In the method of electrodepositing the electroactive species onto a solid, step (d) may be repeated several times to create multiple layered structures. The electroactive species may be any chemical species capable of participating in controlled redox reactions.

[0056] On one side, pressure can be applied to the layered structure at pressures of 0.1-100 MPa, 0.2-100 MPa, 0.4-100 MPa, 0.6-100 MPa, 0.8-100 MPa, 1-100 MPa, 1.2-100 MPa, 1.4-100 MPa, 1.6-100 MPa, 1.8-100 MPa, 2-100 MPa, 10-100 MPa, or 50-100 MPa. On another note, the pressure can be 0.1 to 100 MPa, or 0.1 to 50 MPa, or 0.1 to 10 MPa, or 0.1 to 5 MPa, or 0.1 to 2 MPa, or 0.1 to 1.8 MPa, or 0.1 to 1.6 MPa, or 0.1 to 1.4 MPa, or 0.1 to 1.2 MPa, or 0.1 to 1 MPa, or another range suitable for pressurizing layered structures.

[0057] On one side, the layered structure can be pressed at a temperature of 25°C to 180°C, or 50°C to 180°C, or 100°C to 180°C, or 125°C to 180°C, or 140°C to 180°C, or 145°C to 180°C, or 150°C to 180°C, or 155°C to 180°C, or 160°C to 180°C. On another side, the temperature can be 25°C to 180°C, or 25°C to 175°C, or 25°C to 170°C, or 25°C to 165°C, or 25°C to 160°C, or another range suitable for pressing the layered structure.

[0058] In one embodiment, step (d) of the method may further include passing a current using a series of pulse cycles, each pulse cycle including (i) supplying an on-current for a given pulse width and (ii) supplying an off-current for a fixed length of time based on the duty cycle and pulse width. Electroactive species (e.g., lithium) nucleate and grow during the on-current and are pressured and flattened during the off-current. FIG. 1A is an exemplary schematic diagram of a pulsed current electroplating profile and pulse parameters according to one embodiment of the present disclosure. Each pulse cycle includes an on-current density value j on , a pulse width t on , an off-current density j off , and an off-current time t off , where the off-current density value j off is smaller than the on-current density value j on , and the off-current time t off is shorter than the pulse width t on . The on-current flows for a time called the pulse width t on , followed by the off-current flowing for a time t off .

[0059] In one embodiment, the on-current in step (d) may have a non-zero current density value j on and bears most of the electrodeposition. On one side, the on-current is 1 μA / cm 2 to 1 A / cm 2 , or 0.01 mA / cm 2 to 1 A / cm 2 , or 0.1 mA / cm 2~1A / cm 2 , or 0.2 mA / cm² 2 ~1A / cm 2 , or 0.4 mA / cm² 2 ~1A / cm 2 , or 0.6mA / cm 2 ~1A / cm 2 The density value j on It has. On another side, the on current is 1 μA / cm 2 ~1A / cm 2 , or 1 μA / cm 2 ~0.1A / cm 2 , or 1 μA / cm 2 ~100mA / cm 2 , or 1 μA / cm 2 ~1mA / cm 2 , or 1 μA / cm 2 ~0.8mA / cm 2 , or 1 μA / cm 2 ~0.6mA / cm 2 , or another range of density values ​​j suitable for electrodeposition on It holds.

[0060] In one embodiment, the on-current of step (d) is the pulse width t on It may have a pulse width t. on t is the length of time the on-current is supplied, and may have a value in the range of 1 μs to 100 seconds, or 100 μs to 100 seconds, or 1 m s to 100 seconds, or 100 m s to 100 seconds, or 1 second to 100 seconds, or 10 seconds to 100 seconds, or 1 μs to 10 seconds, or 1 μs to 1 second, or 1 μs to 100 m s, or 1 μs to 1 m s, or another range suitable for electrodeposition. In one embodiment, the on-current in step (c) has a pulse width t of 1 second to 10 seconds. on It may have.

[0061] In one embodiment, the off-current in step (d) is the on-current j on A density value j smaller than the density value of off This can result in zero electrodeposition, partial electrodeposition, or peeling of the electrodeposited material. On one side, the off-current is -1 A / cm 2 ~0.9 μA / cm 2 , or -0.5A / cm2 ~0.9 μA / cm 2 , or -0.1 A / cm 2 ~0.9 μA / cm 2 The density value j off It may have. On another side, the off-current is -1A / cm 2 ~0.9 μA / cm 2 , or -1 A / cm 2 ~0.5 μA / cm 2 , or -1 A / cm 2 ~0.2 μA / cm 2 , or -1 A / cm 2 ~0.1 μA / cm 2 Alternatively, it may have a density value in a different range suitable for electrodeposition.

[0062] In one embodiment, the duty cycle of step (d) is the proportion of time during which the ON current is supplied in a single ON / OFF cycle, and is calculated by the following formula:

number

[0063] In another embodiment, the method may further include monitoring the propagation of electroactive species from the anode to the solid electrolyte while an electric current is passed through the layered structure using a series of pulse cycles. Video microscopy is a non-limiting exemplary technique for monitoring the propagation of electroactive species from the anode to the solid electrolyte. Each pulse cycle may include (i) supplying an on-current for a given pulse width and (ii) supplying an off-current for a certain length of time based on the duty cycle and pulse width. This embodiment of the method includes varying at least one of (i) pulse width, (ii) a certain length of time, (iii) duty cycle, (iv) a first current density value of the off-current, and (iv) a second current density value of the on-current, when prediction of the propagation of electroactive species from the anode to the solid electrolyte is performed by monitoring.

[0064] In another embodiment, step (b) of the method may further include evaporating a first layer of metal on a solid electrolyte material, and then pressing a metal foil onto the first layer such that the electrode consists of the first layer of metal and a metal foil. In one embodiment, the metal may be lithium. In one embodiment, the metal foil may be lithium foil. Lithium metal may be deposited as an initial layer on both sides of the solid material using an Angstrom Engineering lithium evaporator. Then, the lithium foil may be pressed onto the initially evaporated lithium layer at any of the above pressures.

[0065] More generally, the present disclosure provides a method for electrodepositing electroactive species onto a solid substrate. In one embodiment, the method may include passing a pulsed current through a layered structure including a substrate coated with a solid electrolyte material in contact with electrodes containing electroactive species, thereby creating an interfacial layer (e.g., electroplating) between the solid electrolyte material and the substrate. The pulsed current includes supplying a non-zero DC on-current for a given pulse width. The on-current is 1 μA / cm². 2 ~1A / cm 2 , or 0.01 mA / cm² 2 ~10mA / cm 2 , or 0.1 mA / cm2 ~1mA / cm 2 , or 0.1 mA / cm 2 ~0.6mA / cm 2 The pulse width may be 1 to 10 seconds, or 2 to 8 seconds, or 4 to 6 seconds. The on-current is followed by an off-current with a lower current density for a certain length of time determined by the duty cycle. The off-current is -1 A / cm². 2 ~0.9 μA / cm 2 , or -0.1 μA / cm 2 ~0.1 μA / cm 2 The duty cycle may be 0.1% to 99%, or 50% to 99%, or 70% to 99%. A series of on-pulses and off-pulses are then periodically repeated until an appropriate mass of material is electroplated. The interface layer may have a uniform thickness. The electrodes may contain lithium metal. The electrodes may be composed essentially of lithium metal. The current may generate 1 to 300, 5 to 60, 10 to 30, or 2 to 12 interface layers and their corresponding electrochemical cells within a single electrochemical device. The electrodes may have a thickness of 1 nm to 100 μm, 10 nm to 50 μm, or 100 nm to 10 μm. The pulsed current may be supplied for 0.01 hours, 0.1 hours, 0.5 hours, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 18 hours, 24 hours, or 48 hours or more. The formation current may be supplied all at once, or it may be supplied in multiple charging cycles. [Examples]

[0066] The following examples illustrate specific embodiments and aspects of the present invention and are provided for illustrative purposes only; they should not be construed as limiting the scope of the invention. [Examples]

[0067] Cell assembly A lithium lanthanum zirconium oxide (LLZO) with a garnet structure was used as a solid-state Li ion conductor to perform electrodeposition of a metallic Li film. The substrate for Li deposition was a 35 μm Ni foil (Targray), and Li + The source was a 200 μm Li foil (Alfa Aesar). To assemble the electrochemical cell, following the description by Rangasamy et al. [Reference 12], Li 6.5 La3Zr 1.5 Ta 0.5 O 12 Ta-stabilized LLZO powder with the specified composition was synthesized, and then densified and diffusely bonded simultaneously by rapid induction hot pressing to bond it to a Ni substrate. Subsequently, the LLZO surface was heat-treated in Ar to remove surface contaminants, and a Li source was attached using the procedure described above [Reference 13].

[0068] Li metal electrodeposition After attaching the Li foil, the cell was heated in an Ar-filled glove box at a pressure of approximately 1 MPa and a temperature of 160°C using a custom cell fixture. Then, at 160°C, the voltage was increased to 0.05 mA / cm² until the potential relative to the Li electrode dropped from the open-circuit potential to 0V. 2 A constant current is supplied to deposit Li metal. When the potential reaches 0V, the program is switched to a pulsed current method, and Li metal is deposited on the Ni substrate during the on-current pulse. Electrochemical impedance spectroscopy (EIS) was performed before and after plating to confirm the presence of electroplated Li and to check the integrity of the cell. EIS was performed with a perturbation voltage of 1mV at a frequency of 500mHz to 7MHz.

[0069] Electrochemical analysis Figure 2A shows the potential response when a Li metal source is used as both the counter electrode and the reference electrode. It can be seen that as the ionic current flows toward the Ni substrate, the potential drops from the open-circuit potential to 0V, and Li begins to electrodeposit when the potential is below 0V relative to the Li electrode. When the potential reaches 0V, the current switches from a constant DC current to a current pulse program, with an on-current of 0.1 mA / cm². 2 ~0.6mA / cm 2The off-current is 0mA / cm². 2 The pulse width is 5 seconds, and the duty cycle is 80% to 100% (DC current). The potential during the on-current pulse shows a minimum value near the start of the pulse program, which indicates Li nucleation on the substrate, but the steady-state potential thereafter indicates steady-state Li deposition. The potential during the off-current pulse is close to 0V, which represents the open-circuit potential of the Li / LLZO / Li cell. Figure 2B shows the EIS spectra of the cell before and after Li electrodeposition. When assembled, the EIS spectrum shows a low-frequency capacitive tail due to the blocking properties of Ni to Li [Reference 14]. However, after electrodeposition, the capacitive tail almost completely disappears, which is closer to the state of a cell using a non-blocking Li electrode. This suggests that the Li metal was well deposited at the interface. A distinct characteristic of the plated Li is that it is very dense. The trace in the EIS is a transition from blocking behavior to non-blocking behavior (see Figure 2B), where non-blocking means that the electrode can be considered to react with lithium electroactive species. A leftward shift in the Re(Z) axis intercept is thought to indicate the start of dendritic crystal formation. Figure 2B shows a plot in which no dendritic crystal formation is observed, and the absence of a leftward shift indicates that the cell is not short-circuited internally and is therefore functioning. Furthermore, the absence of changes in the spectrum at higher frequencies suggests that no damage occurred to the solid electrolyte during the precipitation process. Damage refers to the penetration of Li dendritic crystals into the solid electrolyte. When dendritic crystals form, cracks, or traces, are formed. In this embodiment, since dendritic crystals do not form, there are no traces in the form of cracks in the solid electrolyte.

[0070] Visual inspection Panels a) to e) of Figure 3 show the LLZO surface after the Ni substrate has been removed following Li electrodeposition. Since the adhesion strength of Li on the LLZO is much greater than that on Ni [Reference 15], most of the Li remains attached to the LLZO even after the Ni foil is removed. It can be seen that a considerable amount of Li, comparable to the thickness of the Ni substrate, can be plated. The presence of metallic Li is consistent with the AC impedance and DC potential responses. Panels a) to e) of Figure 3 show the distribution of electrodeposited Li on the LLZO surface with varying pulse parameters, demonstrating significant differences depending on the parameter. A comparison of duty cycles of 100% (DC current) and 83% demonstrates the effectiveness of current pulses in achieving a uniform layer of electrodeposited Li. Furthermore, a comparison of high and low on-current densities demonstrates the effect of current density on initial nucleation behavior and nucleus growth. Panel b) of Figure 3 shows an exemplary form of electrodeposited lithium at a 100% duty cycle (DC current) according to one embodiment of the present disclosure. Panel c) of Figure 3 shows an exemplary form of electrodeposited lithium with an 80% duty cycle and low current density according to one embodiment of the present disclosure. Panel d) of Figure 3 shows an exemplary form of electrodeposited lithium with an 80% duty cycle and high current density according to one embodiment of the present disclosure. Panel e) of Figure 3 shows an exemplary form of electrodeposited lithium with a considerable amount of lithium deposited beyond the thickness of the nickel substrate according to one embodiment of the present disclosure. Without pulsing (see panel b) of Figure 3), the Li coverage of the LLZO surface is only about 60%. With pulsing (see panels d) and e) of Figure 3), the surface coverage is very good, exceeding 95%.

[0071] Therefore, it is clear that optimizing pulse parameters is possible to improve the uniformity of the electrodeposited metal at the solid-solid interface. Alternatively, optimizing pulse parameters can also be used to create locally thick electrodeposited films. [Examples]

[0072] overview Example 2 relates to a method for electrodepositing electroactive species at a solid-solid interface. It has been demonstrated that an intermediate metal layer can be nondestructively electrochemically deposited at the interface between a solid electrolyte and a metal foil. The desired morphology of the solid electrolyte / metal interface is characterized and identified. The following method can assist in the fabrication of thin films for application in advanced functional materials and electrochemical devices.

[0073] Introduction Electrochemical deposition is a widely useful method for the controlled fabrication of microstructures and precision engineering of surfaces. In typical electrodeposition processes, electroactive species, generally metal cations, are electrochemically deposited from a liquid electrolyte onto a metal substrate. Because the electrolyte is in a liquid state, it readily adapts to the volume expansion associated with the deposition of electroactive species. However, when a solid electrolyte is bonded to a metal substrate, this volume expansion is not easily accommodated, and it is necessary to forcibly delaminate the electrolyte and metal substrate to accommodate the growth of an intermediate phase. Based on the mechanical properties and geometric shapes of both the electrolyte and the metal substrate, the forced delamination required to electrodeposit the electroactive species may irreversibly destroy one of the components [References 16-19]. Furthermore, the stress generated by the electrodeposition process is directly correlated with electrochemical conditions, including interfacial resistance and electrodeposition current. With development aimed at applications in batteries and fuel cells, electrodeposition at solid-solid interfaces is increasingly necessary to accurately fabricate active metal films at solid-solid interfaces. Therefore, a robust and non-destructive method is required for the electrodeposition of electroactive materials at solid-solid interfaces.

[0074] Cell assembly Lithium lanthanum zirconium oxide (LLZO) was used as a solid Li ion conductor to perform electrodeposition of a metallic Li film. The substrate for Li deposition was a 10 μm Cu foil (Targray), and Li +The source material was a 500 μm Li foil (Alfa Aesar). The electrochemical cell was first assembled by synthesizing and densifying Ta-stabilized LLZO according to Taylor et al.'s description [Reference 20]. Next, the LLZO was cut into 2 mm discs, polished with 1200 grit sandpaper, and diffusely bonded to a Cu substrate by rapid induction hot pressing at 900°C for 5 minutes. After that, this structure was heat-treated in Ar, and as described above, Li foil was attached at a temperature of 170°C and a pressure of approximately 1 MPa [Reference 21].

[0075] Li metal electrodeposition At room temperature and under a pressure of 4 MPa, a flow rate of 0.05 mA / cm² is applied until the desired amount of Li metal is deposited on the Cu substrate. 2 A constant current is supplied to deposit Li metal. Electrochemical impedance spectroscopy is performed before and after plating to confirm the presence or absence of electroplated Li and to check the integrity of the cell. EIS is performed with a perturbation voltage of 5mV at a frequency of 500mHz to 7MHz.

[0076] Material property evaluation Cross-sections were extracted and imaged using focused ion beam (FIB) milling, and analyzed using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) with a Thermo Fisher Helios G4 Plasma FIB UXe. Figure 4 shows the SEM cross-section of the cell assembly. Figure 4A shows the initial state of the assembled cell, indicating that there is almost no gap between the Cu layer and the LLZO layer. Figure 4B shows 5 mAh / cm 2 The interface after Li metal plating is shown, and the appearance of the intermediate phase is also shown. The intermediate phase could not be identified by EDS, and since Li metal is outside the detection range of this technique, it is suggested that the substance is Li metal. Figure 4C shows the interface with the polarity reversed and a current of 5 mAh / cm². 2This shows the interface after Li has been removed. It can be seen that the intermediate phase has disappeared and been replaced by a gap of 5-10 μm, further suggesting that the intermediate phase is actually Li metal. Panels a-c of Figure 5 show the same cross-section at lower magnification, illustrating in more detail the uniformity of the observed interface morphology. Panel d of Figure 5 also shows the alternative morphology of the interface after Li removal; the gap is less noticeable than in panel c of Figure 5, but more noticeable than the initial interface shown in panel a of Figure 5.

[0077] Accordingly, the present invention provides an electrodeposition method that uses pulsed current to improve the uniformity of electrodeposited materials at solid-solid interfaces. In one embodiment, the method enables anode-free manufacturing, in which a battery is manufactured in a discharged state by replacing the conventional anode with a bare current collector, and then a metal anode is electrochemically formed in the first charging cycle by electroplating the metal contained in the cathode.

[0078] In light of the principles and exemplary embodiments described and illustrated herein, it will be recognized that the exemplary embodiments can be improved in arrangement and detail without departing from such principles. Furthermore, while the above description focuses on specific embodiments, other configurations are also envisioned. In particular, where expressions such as “in one embodiment” or “in another embodiment” are used in this specification, these phrases generally mean that they refer to possible embodiments and are not intended to limit the invention to the configuration of a particular embodiment. Where used in this specification, these terms may refer to the same or different embodiments that can be combined with other embodiments. In principle, any embodiment referred to in this specification may be freely combined with any one or more of the other embodiments referred to in this specification, and any number of features of different embodiments may be combined with each other unless otherwise indicated.

[0079] Although the present invention has been described in considerable detail with reference to specific embodiments, it will be apparent to those skilled in the art that the invention can be carried out in alternative embodiments other than those described herein, and the embodiments described herein are presented for illustrative purposes only and are not intended to limit the invention. Therefore, the appended claims should not be limited to the descriptions of the embodiments included in this specification.

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[16] Krauskopf, T. et al., "Lithium-Metal Growth Kinetics on LLZO Garnet-Type Solid Electrolytes", Joule S2542435119303010 (2019) doi:10.1016 / j.joule.2019.06.013.

[17] Motoyama, M., Ejiri, M. & Iriyama, Y., "Modeling the Nucleation and Growth of Li at Metal Current Collector / LiPON Interfaces", J. Electrochem. Soc. 162, A7067-A7071 (2015).

[18] Motoyama, M. et al., "The Active Interface of Ta-Doped Li7La3Zr2O 12 for Li Plating / Stripping Revealed by Acid Aqueous Etching", ACS Appl. Energy Mater. acsaem.9b01193 (2019) doi:10.1021 / acsaem.9b01193.

[19] Motoyama, M., Ejiri, M. & Iriyama, Y., "In-Situ Electron Microscope Observations of Electrochemical Li Deposition / Dissolution with a LiPON Electrolyte", Electrochemistry 82, 364-368 (2014).

[20] Taylor, N.J. et al., "Demonstration of high current densities and extended cycling in the garnet Li7La3Zr2O 12 solid electrolyte", J. Power Sources 396, 314-318 (2018).

[21] Wang, M., Wolfenstine, JB & Sakamoto, J., “Temperature dependent flux balance of the Li / Li7La3Zr2O 12 ", Electrochimica Acta 296, 842-847 (2019). The citation of any document should not be interpreted as acknowledging it as prior art of the present invention.

Claims

1. A method for manufacturing electrochemical devices, (a) A step of preparing a current collector coated with a solid electrolyte material, (b) The step of bringing the solid electrolyte material into contact with an electrode containing an electroactive species to form a layered structure, wherein the current collector includes the outer surface of the layered structure. (c) The step of applying a pressure of 1 MPa to 10 MPa to the layered structure, (d) A step of passing an electric current through the layered structure using a series of pulse cycles to form an interface layer containing the electroactive species between the solid electrolyte material and the current collector. Includes, A method in which the interface layer functions as the anode of the electrochemical device and the electrode functions as the cathode of the electrochemical device.

2. The method according to claim 1, wherein step (c) includes applying a pressure of 1 MPa to 5 MPa to the layered structure.

3. The method according to claim 1, wherein step (c) includes applying a pressure of 1 MPa to 2 MPa to the layered structure.

4. Each pulse cycle includes (i) supplying an on current for a given pulse width, and (ii) supplying an off current for a certain length of time based on the duty cycle and the pulse width. The method according to claim 1, wherein the off-current has a first current density value smaller than the second current density value of the on-current.

5. The aforementioned ON current is 1 μA / cm ２ ~1 A / cm ２ The method according to claim 4, wherein the DC is within the range of [specify range].

6. The aforementioned ON current is 0.01 mA / cm². ２ ~1 mA / cm ２ The method according to claim 4, wherein the DC is within the range of [specify range].

7. The current is 1 μA / cm ２ ~1 mA / cm ２ The method according to claim 1, wherein the DC is within the range of [specify range].

8. The method according to claim 4, wherein the pulse width is 1 μs to 100 seconds.

9. The method according to claim 4, wherein the pulse width is 1 second to 10 seconds.

10. The aforementioned off-current is -1 A / cm ２ ~0.9 μA / cm ２ The method according to claim 4, wherein the DC is within the range of [specify range].

11. The method according to claim 4, wherein the duty cycle is 0.1% to 99%.

12. The method according to claim 4, wherein the duty cycle is 50% to 99%.

13. The method according to claim 4, wherein the duty cycle is 70% to 99%.

14. The method according to claim 4, wherein the duty cycle is 80% to 99%.

15. Step (d) further includes monitoring the propagation of the electroactive species from the anode to the solid electrolyte while the current is passed through the layered structure using the series of pulse cycles, Each pulse cycle includes (i) supplying an on current for a given pulse width, and (ii) supplying an off current for a certain length of time based on the duty cycle and the pulse width. The method according to claim 1, further comprising step (d) varying at least one of (i) the pulse width, (ii) the constant length of time, (iii) the duty cycle, (iv) a first current density value of the off current, and (iv) a second current density value of the on current, when the prediction of the propagation of the electroactive species from the anode to the solid electrolyte is performed by the monitoring.

16. The method according to claim 1, wherein the current collector comprises a single material including a metal or a metal alloy.

17. The method according to claim 16, wherein the current collector comprises a material selected from the group consisting of nickel, molybdenum, titanium, zirconium, tantalum, alloy steel, stainless steel, nickel-based superalloy, cobalt-based superalloy, copper, aluminum, iron, or mixtures thereof.

18. The method according to claim 1, wherein the current collector has a thickness of 1 nm to 100 μm.

19. The method according to claim 1, wherein the solid electrolyte material comprises a material selected from the group consisting of lithium oxynitride phosphate (LiPON), oxide garnet, sodium superionic conductor (NaSICON), lithium superionic conductor (LiSICON), thioLiSICON, sulfide glass, polymer, or mixtures thereof.

20. The method according to claim 1, wherein the solid electrolyte material is selected from the group consisting of lithium lanthanum zirconium oxide (LLZO), aluminum-doped LLZO, gallium-doped LLZO, niobium-doped LLZO, tantalum-doped LLZO, lithium aluminum titanium phosphate (LATP), lithium aluminum germanium phosphate (LAGP), lithium phosphorus sulfide (LPS), poly(ethylene oxide) (PEO), polyacrylonitrile (PAN), crystalline thermoplastic polymer, alkali metal cation alumina, metal halide, or mixtures thereof.

21. The method according to claim 1, wherein the solid electrolyte material comprises lithium lanthanum zirconium oxide (LLZO) or a derivative thereof.

22. The solid electrolyte material contains Li ｗ A ｘ M ２ Re ３－ｙ O ｚ and includes a ceramic material having a chemical formula of, where in the formula w is 5 to 7.5, A is selected from B, Al, Ga, In, Zn, Cd, Y, Sc, Mg, Ca, Sr, Ba, and any combination thereof. x is between 0 and 2, M is selected from Zr, Hf, Nb, Ta, Mo, W, Sn, Ge, Si, Sb, Se, Te, and any combination thereof. Re is selected from lanthanide elements, actinide elements, and any combination thereof. y is between 0 and 0.

75. z is between 10.875 and 13.

125. The method according to claim 1, wherein the ceramic material has a garnet-type or garnet-like crystalline structure.

23. The method according to claim 22, wherein M is a combination of Zr and Ta.

24. The method according to claim 22, wherein M is Zr, A is Al, and x is not 0.

25. The method according to claim 22, wherein M is Zr, A is Ga, and x is not 0.

26. The method according to claim 1, wherein the solid electrolyte material is sodium β-alumina and sodium β''-alumina.

27. The method according to claim 1, wherein the solid electrolyte material is coated onto the current collector using at least one of the following methods: diffusion bonding, chemical vapor deposition, physical vapor deposition, atomic layer deposition, slurry casting sintering, slurry casting hot pressing, painting, powder coating, thermal spraying, low-temperature thermal spraying, aerosol deposition, flux deposition, electrodeposition, electroless chemical deposition, or a combination thereof.

28. The method according to claim 1, wherein the solid electrolyte material has a thickness of 1 nm to 100 μm.

29. The method according to claim 1, wherein the interface layer has a thickness of 1 nm to 100 μm.

30. The method according to claim 1, wherein the current collector electrochemically blocks the electroactive species.

31. The method according to claim 1, wherein the current collector includes a bimetal having a first layer made of a first metallic material and a second layer made of a second metallic material, the first layer being at least partially in contact with the solid electrolyte material prior to step (d), and the second layer being in contact with the first layer.

32. The method according to claim 31, wherein the first metal material electrochemically blocks the electroactive species.

33. The first metallic material is selected from the group consisting of nickel, molybdenum, titanium, zirconium, tantalum, nickel-based superalloys, cobalt-based superalloys, copper, or mixtures thereof. The second metallic material is selected from the group consisting of aluminum, nickel, alloy steel, stainless steel, nickel-based superalloys, or mixtures thereof. The method according to claim 31.

34. The first metal material contains nickel, The method according to claim 31, wherein the second metal material includes stainless steel.

35. The method according to claim 31, wherein the first layer has a thickness of 1 nm to 100 μm, and the second layer has a thickness of 1 nm to 100 μm.

36. The method according to claim 1, wherein the electrode comprises a single material consisting of a metal or a metal alloy.

37. The method according to claim 1, wherein the electrode comprises a material selected from the group consisting of lithium, sodium, silver, magnesium, calcium, cobalt, iron, potassium, copper, or mixtures thereof.

38. The method according to claim 1, wherein the electrode contains lithium.

39. The electrode is (i) LiC ６ (ii) Lithium metal oxides in which the metal is one or more of aluminum, cobalt, iron, manganese, nickel and vanadium, and (iii) LiMPO ４ The method according to claim 1, comprising a lithium host material selected from the group consisting of lithium-containing phosphates having the general chemical formula, wherein M is one or more of cobalt, iron, manganese, and nickel.

40. The method according to claim 39, wherein the electrode further comprises a binder and a conductive additive.

41. The method according to claim 40, wherein the binder comprises a polymer material and the conductive additive comprises a carbon compound.

42. The method according to claim 1, wherein the electrode is a conductive composite material containing the electroactive species.

43. The method according to claim 1, step (b) comprising evaporating the first layer of lithium on the solid electrolyte material, and then pressing the lithium foil onto the first layer such that the electrode consists of the first layer of lithium and the lithium foil.

44. The method according to claim 1, wherein step (c) includes applying the pressure to the layered structure at a temperature of 25°C to 180°C.

45. The method according to claim 1, wherein no damage occurs to the solid electrolyte material during step (d).

46. The method according to claim 1, wherein no penetration of dendritic crystals into the solid electrolyte material occurs during step (d).

47. The method according to claim 1, wherein the interface layer has a uniform thickness after step (d).

48. The method according to claim 1, wherein the interface layer has a surface coverage of 5% or more with respect to the solid electrolyte after step (d).

49. The method according to claim 1, wherein the interface layer has a surface coverage of 70% or more of the solid electrolyte after step (d).

50. The method according to claim 1, wherein the interface layer is in complete surface contact with the solid electrolyte material after step (d).

51. The method according to claim 1, wherein the current collector coated with the solid electrolyte material prepared in step (a) has a porosity of 0.1% to 99% at the interface between the current collector and the solid electrolyte material.

52. The method according to claim 1, wherein the current collector coated with the solid electrolyte material prepared in step (a) has a porosity of 0.1% to 10% at the interface between the current collector and the solid electrolyte material.

53. The interfacial resistance between the current collector prepared in step (a) and the solid electrolyte material is 10,000 Ωcm. ２ The method according to claim 1, wherein the result is less than [value missing].

54. The interfacial resistance between the current collector prepared in step (a) and the solid electrolyte material is 1000 Ωcm. ２ The method according to claim 1, wherein the result is less than [value missing].

55. The interfacial resistance between the interfacial layer and the solid electrolyte after step (d) is 100 Ωcm. ２ The method according to claim 1, wherein the result is less than [value missing].

56. The interfacial resistance between the interfacial layer and the solid electrolyte after step (d) is 25 Ωcm. ２ The method according to claim 1, wherein the result is less than [value missing].

57. The method according to claim 1, wherein the RMS surface roughness of the surface of the solid electrolyte material covered with the current collector is 5 μm or less.

58. The method according to claim 1, wherein the RMS surface roughness of the surface of the solid electrolyte material covered with the current collector is 500 nm or less.

59. The method according to claim 1, wherein the interface layer has a density in which the anode exhibits non-blocking behavior with respect to the electroactive species.

60. The method according to claim 1, wherein the interface layer does not show the formation of dendritic crystals after step (d).

61. The method according to claim 1, wherein the solid electrolyte material comprises doped lithium lanthanum zirconium oxide.

62. The method according to claim 61, wherein the solid electrolyte material includes aluminum-doped lithium lanthanum-zirconium oxide, gallium-doped lithium lanthanum-zirconium oxide, niobium-doped lithium lanthanum-zirconium oxide, or tantalum-doped lithium lanthanum-zirconium oxide.

63. The solid electrolyte material is Li ｗ A ｘ M ２ Re ３－ｙ O ｚ It includes a ceramic material having the chemical formula, in which, w is 5 to 7.5, A is selected from B, Al, Ga, In, Zn, Cd, Y, Sc, Mg, Ca, Sr, Ba, and any combination thereof. x is between 0 and 2, M is selected from Zr or Zr, Hf, Nb, Ta, Mo, W, Sn, Ge, Si, Sb, Se, Te, and any combination thereof. Re is a lantern, y is between 0 and 0.

75. z is between 10.875 and 13.

125. The aforementioned ceramic material has a garnet-type or garnet-like crystal structure. The method according to claim 61.

64. The method according to claim 63, wherein M is a combination of Zr and Ta.

65. The method according to claim 63, wherein M is Zr, A is Al, and x is not 0.

66. The method according to claim 63, wherein M is Zr, A is Ga, and x is not 0.

67. The solid electrolyte material is Li ｗ A ｘ M ２ Re ３－ｙ O ｚ It includes a ceramic material having the chemical formula, in which, w is 5 to 7.5, A is selected from B, Al, Ga, In, Zn, Cd, Y, Sc, Mg, Ca, Sr, Ba, and any combination thereof. x is between 0 and 2, M is selected from Zr, Hf, Nb, Ta, Mo, W, Sn, Ge, Si, Sb, Se, Te, and any combination thereof. Re is selected from lanthanide elements, actinide elements, and any combination thereof. y is between 0 and 0.

75. z is between 10.875 and 13.

125. The aforementioned ceramic material has a garnet-type or garnet-like crystal structure. The method according to claim 1, wherein when x is 0, M is two or more of the following: Zr, Hf, Nb, Ta, Mo, W, Sn, Ge, Si, Sb, Se, and Te.

68. The method according to claim 67, wherein Re is a lantern.

69. The method according to claim 68, wherein M is a combination of Zr and Ta.

70. The method according to claim 68, wherein M is Zr, A is Al, and x is not 0.

71. The method according to claim 68, wherein M is Zr, A is Ga, and x is not 0.

72. The solid electrolyte is Li ６．５ La ３ Zr １．５ Ta ０．５ O １２ The method according to claim 67, including the method described in claim 67.

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