Method for manufacturing a negative electrode of a lithium metal battery using optical electromagnetic energy irradiation, and a negative electrode of a lithium metal battery

Abstract

The present disclosure relates to a lithium metal anode electrode that suppresses the growth of lithium dendrites that degrade the electrochemical properties of a battery and cause fatal damage to the battery structure, and in particular to a method for manufacturing an anode electrode having a three-dimensional highly porosity structure or a metal-based or carbon-based three-dimensional mesh structure, including irradiation with light electromagnetic energy.

Description

[Technical Field]

[0001] The present invention relates to a lithium metal battery. negative electrode Electrodes and methods for their manufacture are disclosed.

[0002] Specifically, the lithium metal battery of the present disclosure negative electrode The electrode manufacturing method includes forming a three-dimensional structure on a substrate by irradiating it with optical electromagnetic energy, negative electrode These include significantly increasing the surface area of ​​the electrode, enhancing lithium ion diffusion, reducing interfacial resistance, and inhibiting lithium dendrite growth.

[0003] In one embodiment, the lithium metal battery negative electrode The method for fabricating an electrode includes forming a three-dimensional structure on a lithium metal substrate, which may be a nanoporous structure of a layer of conductive polymer nanocomposite material or a three-dimensional structure of a carbon frame. In another embodiment, the lithium metal battery negative electrode The electrode manufacturing method involves forming a three-dimensional porous structure of lithium metal composed of copper-silver-carbon nanotubes coated directly onto a current collector. [Background technology]

[0004] As market demand for high-energy density secondary batteries increases, conventional graphite negative electrode A new alternative to negative electrode Among the various candidate materials, lithium metal has a high theoretical capacity (3860mAh / g) and a low density (0.59g / cm 3 ) to lithium secondary battery negative electrode However, lithium metal negative electrode Despite these advantages, there are some significant challenges for large-scale application in lithium secondary batteries: large volume changes during lithiation cycling and the growth of lithium dendrites.

[0005] Lithium dendrites can form during charging. negative electrodeThe metal microstructure formed on the electrode is different due to the different deposition rates. negative electrode Additional lithium ions accumulate on the surface and grow through repeated deposition / dissolution processes, forming lithium dendrites, which can pierce the separator and cause internal short circuits, damaging the battery and leading to catastrophic failure, including fire and explosion.

[0006] When lithium plating occurs during battery use, dendrites grow from nucleation points on the lithium metal surface. The lithium dendrites break down, resulting in irreversible lithium ionization and a decrease in battery capacity. In extreme cases, once lithium dendrites have grown to a certain extent, positive electrode and negative electrode During charge / discharge cycles, the growth of lithium dendrites and the formation of lithium metal negative electrode The volume change can cause physical damage, delamination, and fracture of the solid electrolyte phase interface (SEI) layer. This allows the lithium metal negative electrode A continuous reaction occurs between the SEI layer and the electrolyte, forming a new SEI layer and consuming the electrolyte.

[0007] Lithium dendrite formation process

[0008] Researchers have made considerable efforts to solve the challenges associated with lithium metal batteries and to understand the mechanisms of lithium dendrite formation and growth. Generally, lithium dendrites are formed due to uneven lithium deposition caused by uneven charge distribution. For example, a rough surface on a current collector can cause ion flow to concentrate near the tip of the rough surface, promoting lithium ion deposition near the peak and forming dendrites. The growth points of dendrites (such as the tip of a rough surface) are called nucleation points.

[0009] Theoretically, there are several models for lithium dendrite growth. The Chazlviel model [Chazlviel 1990] states that: negative electrodeIt has been suggested that the depletion of anions near the surface creates a space charge, which in turn leads to the formation of lithium dendrites. This model explains the rate of dendrite growth based on the mobility of ions and the electric field. The time to dendrite appearance follows the Scatchard equation, which states that the time to dendrite appearance decreases as the current density increases.

[0010] Another model proposed by Monroe and Newman [Monroe and Newman 2003] argues that dendrite growth depends on the elasticity of the separator and is suitable for lithium metal batteries with solid electrolytes. This model suggests that dendrite growth can be avoided if the electrolyte's mechanical strength is high enough. However, this solution is not practical because an electrolyte with such a high elastic modulus would reduce ionic conductivity and prevent the battery from cycling properly.

[0011] Dendrite suppression method: electrochemically stable electrolyte

[0012] Many of the other models mentioned above offer refinements and provide basic concepts for suppressing lithium dendrite growth. One approach is to use electrolytes with more stable electrochemical properties, such as anion-coupled mixed electrolytes, especially anionic liquid-nanoparticle mixed electrolytes. An example of such an ionic liquid is 1-methyl-3-propylimidazole (IM) TFSI [Lu et al. 2014]. These electrolytes have stable electrochemical properties, are non-flammable, and have a high dielectric constant. Their electrochemical stability comes from their unique structure, in which anions are connected to cations, and the cations are covalently anchored to inorganic particles. According to the Scatchard model, once the anions are immobilized, the emergence of dendrites takes an infinitely long time.

[0013] Lithium metal, including electrolyte optimization negative electrodeSeveral techniques have been proposed to prevent or inhibit dendrite growth in batteries. However, these methods have a negative impact on the electrochemical properties of the battery. Another method to inhibit dendrite growth is to negative electrode The goal is to add a protective layer to the surface of the electrolyte, forming a stable solid electrolyte interface (SEI) layer. Some studies have shown that a three-dimensional structure can regulate consistent growth by distributing nucleation points uniformly across its surface, thereby forming dendrites rather than dendrites. negative electrode The researchers also found that this structure reduces local current density and prevents the formation of lithium dendrites.

[0014] Such three-dimensional structures may be fabricated using a variety of materials, including three-dimensional carbon paper, carbon nanotubes, carbon fibers, conductive polymer nanocomposites, metal fibers, and even lithium metal itself.

[0015] Lithium metal anode, US 10483534B2

[0016] The present invention is based on a lithium metal layer and a porous conductive layer. negative electrode Regarding electrodes, the porous conductive layer may include two layers: a current collector and a conductive load layer, both of which have multiple voids. It can be made of various materials and form a permeable mesh, netting, or rod-like structure, or a combination thereof. The porous conductive layer provides a larger surface area for lithium deposition, forming a stable SEI and reducing the formation of lithium dendrites. Furthermore, the presence of the porous conductive layer allows lithium dendrites to grow from the lithium metal surface or to approach the lithium metal surface and the separator more closely. Furthermore, negative electrode The conductivity of the alloy is also more uniform, with fewer lithium dendrites.

[0017] The present application describes a lithium metal oxide battery that can suppress dendrite growth and prevent catastrophic failure. negative electrode The basic structure of the three-dimensional structure coated above was described, but the existence of a three-dimensional conductive structure was not shown.

[0018] Lithium metal protective layer and manufacturing method thereof, and battery with lithium metal protective layer, CN111490252A

[0019] This application relates to lithium metal negative electrode The porous protective layer can produce a uniformly dispersed lithium alloy or lithium nitride, improve the lithium ion diffusion ability, and suppress the formation of lithium dendrites. This method can produce a porous protective layer using economical materials. negative electrode is applied to the surface of the protective layer in a slurry, which is then dried to form a protective layer. The material of the protective layer includes a metal compound, a conductive agent, and a binder. The metal compound may be a metal nitride, alumina, aluminum fluoride, or non-lithiated tetraaluminum. In this application, lithium metal negative electrode The process of forming the porous structure has been described in detail above, but it is limited to a simple deposition process of a slurry and a simple drying process.

[0020] Surface modification of lithium metal electrodes, DE102013114233A1

[0021] In the present application, in order to suppress the growth of lithium dendrites, lithium metal negative electrode (or other metals negative electrode It has been proposed to directly modify the surface structure of metals. negative electrode Grooves of various geometric shapes, such as blind hole-like grooves and tapered grooves, are formed on the surface of the mold. The cross section of the grooves can be rectangular, trapezoidal, dome-shaped, or triangular. During molding, the desired groove shape is created using a rolling roll, a microneedle roll, or a laser. When using soft metals such as lithium metal, grooves are formed on both sides of the groove using a special method during molding.

[0022] metal negative electrodeThe grooves in the electrode increase the surface area. This increases the surface area, improving discharge and charge rates, cycling stability, and ultimately reducing interfacial resistance. Furthermore, improved cycling stability reduces dendrite growth.

[0023] Surface modification of lithium metal electrodes, KR100449765B1

[0024] The present application relates to a lithium metal separator comprising an integrated separator layer, a current collector layer, and a protective film layer. negative electrode The separator layer may be made of porous polyethylene, polypropylene, or a multilayer structure thereof. Due to the low electrolyte leakage rate, the protective film layer between the separator and the lithium metal layer has high lithium ion conductivity. The protective film may contain organic and inorganic materials.

[0025] This application relates to a lithium metal electrode having an integrated separator layer and protective layer, but the manufacture of the protective layer does not involve post-treatment of the raw material to improve the material properties.

[0026] Ti 2 Anode for lithium metal battery containing C thin film, method for producing same, and lithium metal battery containing said anode for lithium metal battery, KR 20190102489A

[0027] In this application, lithium metal negative electrode It has been proposed that forming a Ti2C thin film on a substrate can form a stable SEI and suppress the formation of lithium dendrites. The Ti2C thin film can induce rapid and stable diffusion of lithium ions and prevent the formation of lithium dendrites. It can also prevent unwanted galvanometric reactions between lithium metal and the electrolyte, improving the stability of the SEI. Furthermore, this application also describes a method for forming a Ti2C thin film on a substrate using a solution containing dispersed Ti2C powder, the Langmuir-Blodgett scooping (LBs) method, and a method for dissolving the formed Ti2C thin film in lithium metal. negative electrode This invention relates to a method for transferring a color to a surface of a substrate.

[0028] This paper proposes an effective method to suppress the growth of dendrites, but the formation of Ti2C thin film and lithium metal negative electrode Its transfer to lithium metal negative electrode This involves a lengthy etching process, which is time-consuming and expensive.

[0029] Coated lithium electrodes, US6955866B2

[0030] This application is negative electrode is a ternary alloy layer consisting of lithium and two other metals, negative electrode Specifically, a first metal other than lithium provides a matrix to accommodate volume changes during lithium cycling, and a second metal is alloyed with the lithium and the first metal. The first metal may be copper and the second metal may be tin. The lithium metal coated with the ternary alloy layer negative electrode is higher negative electrode The stability and lithium cycling efficiency are shown. However, this method necessarily involves alloying lithium with other metals.

[0031] stabilized lithium negative electrode Interface processing, US10256448B2

[0032] The present application provides a lithium metal composite comprising an interfacial layer that controls the reactivity of lithium metal with an electrolyte and can accommodate significant volume changes during lithiation cycling. negative electrode The interfacial layer allows lithium ions to pass through its wall. It also forms a stable solid electrolyte interface (SEI) on one side of the interfacial layer, which can isolate the deposition and dissolution of lithium metal on the other side. The interfacial layer allows lithium ions to pass through its wall. negative electrode The interfacial layer and the lithium metal negative electrode With a space between them, lithium metal negative electrode Loosely attach to the

[0033] The interfacial layer contains two-dimensional atomically crystalline layered materials consisting of graphene and h-BN (hexagonal boron nitride). These materials are chemically inert to electrolytes and lithium metal, and are robust and durable. Furthermore, they are characterized by small pore size, ultrathinness, and flexibility. However, h-BN is an insulator, so it cannot be used directly without graphene.

[0034] This paper proposes an effective method to mechanically and chemically control the reactivity of lithium metal, but the formation of the graphene-h-BN interfacial layer requires high temperatures (1000 °C) and a controlled environment, making it an expensive process.

[0035] Lithium metal negative electrode for lithium metal polymer secondary battery including spacer and method for forming same, KR100582558B1

[0036] The present application relates to lithium metal electrodes separated by grid-like spacers. negative electrode The spacers are laminated on the current collector and are thicker than the lithium metal film. The openings between the spacers may be polygonal, circular, or elliptical, and the spacers are made primarily of glass-reinforced fiber, carbon fiber, or alumina.

[0037] During lithiation cycling, the volume of the separated lithium metal film increases in the gap between the spacers, allowing the lithium metal to be charged without changing the actual battery volume. negative electrode The volume of the electrolyte can be changed, thereby maintaining the SEI and improving the stability of lithium metal batteries.

[0038] The above-mentioned method suppresses the formation of dendrites and prevents the formation of lithium metal in lithium secondary batteries. negative electrode Various methods have been proposed to improve the stability of the battery, but although these methods have improved the stability of the battery to some extent, they are not economical solutions for mass production.

[0039] Prior art documents

[0040] Patent documents

[0041] (Document 001) US 10,483,534 B2

[0042] (Document 002) CN 111490252 A

[0043] (Document 003) DE 102013114233 A1

[0044] (Document 004) KR 10-0449765 B1

[0045] (Document 005) KR 2019-0102489 A

[0046] (Document 006) US 6,955,866 B2

[0047] (Document 007) US 10,256,448 B2

[0048] (Document 008) KR 10-0582558 B1

[0049] non-licensed literature

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[0052] (Reference 003) C. Monroe and J. Newman, J. Electrochem. Soc., 2003, 150, A1377 (Journal of the Electrochemical Society)

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[0055] (Reference 006) C. Monroe and J. Newman, J. Electrochem. Soc., 2005, 152, A396 - A404 ("Journal of the Electrochemical Society")

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[0063] (Directory014)J. Yu , Y. Dang , M. Bai , J. Peng , D. Zheng , J. Zhao , L. Li , Z. Fang , 2019, Front. Chem., DOI: 10.3389 / fchem.2019.00748.

[0064] (Reference 015) T. Wang, RV Salvatierra, AS Jalilov, J. Tian, ​​JM Tour, 2017, ACS Nano, 11, 10761 - 10767. DOI: 10.1021 / acsnano.7b05874. Summary of the Invention [Problem to be solved by the invention]

[0065] This disclosure proposes a method for fabricating electrodes that differs from conventional methods. The proposed method relies on light electromagnetic energy irradiation to form a three-dimensional nanoporous structure, thereby preventing the growth of lithium dendrites and allowing lithium metal to be deposited. negative electrode This can improve the stability of the system, ensuring energy efficiency and applicability to current manufacturing processes.

[0066] The present disclosure provides a method for suppressing the growth of lithium dendrites and improving the lithium metal content in lithium secondary batteries. negative electrode The present invention provides a method for improving the stability of lithium metal. In this method, a three-dimensional structure can be formed in a short time by applying optical electromagnetic energy. negative electrode The three-dimensional porous structure shown above is made of lithium metal. negative electrode The three-dimensional porous structure is related to the lithium plating layer and has a uniform distribution, which prevents the growth of lithium dendrites and maintains a stable SEI.

[0067] The present disclosure relates to lithium metal negative electrode We propose a conductive nanoporous coating made of a nanocomposite material that can be applied to the surface of a substrate. The conductive nanoporous composite material is produced by irradiating a mixture containing a polymer matrix, a conductive additive, and an evaporative additive with a low melting point with light electromagnetic energy (e.g., intense pulsed light (IPL)).

[0068] The present disclosure relates to lithium metal negative electrodeWe propose a 3D carbon nanotube structure that can be applied to the surface of a metal oxide solution. A 3D carbon nanotube frame is generated by irradiating a mixture of randomly dispersed high-aspect-ratio carbon nanotubes with light electromagnetic energy (e.g., IPL).

[0069] The present disclosure provides a lithium metal current collector integrated with a three-dimensionally shaped copper, silver, and carbon nanotube-based current collector. negative electrode We propose a three-dimensional structure of the lithium metal by electroplating lithium on the current collector. negative electrode The surface of the current collector is pretreated with a three-dimensional structure of copper, sintered ore, and carbon nanotubes, and then sintered by irradiation with light electromagnetic energy (e.g., IPL) to obtain carbon nanotubes.

[0070] The present disclosure proposes a cooling system for dissipating waste heat from the lithium metal that accumulates during light electromagnetic energy exposure.

[0071] Furthermore, the present disclosure provides a method for using sandblasting techniques to remove lithium metal oxide particles to increase the adhesion of protective coating materials and reduce contact resistance. negative electrode The surface treatment of the above is also described.

[0072] In one embodiment, a lithium metal battery negative electrode The electrode includes a current collector, a lithium metal layer provided on the current collector, a protective layer having a three-dimensional open-cell porous structure provided on the lithium metal layer, and a lithium alloy metal provided on the surface of the protective coating.

[0073] The lithium metal layer may have an engineered surface texture.

[0074] The protective coating may be a polymer nanocomposite layer comprising an open-cell nanoporous polymer matrix, a conductive carbon additive, and a structural support material.

[0075] The protective coating may include a carbon nanofiber mattress having a three-dimensional open-cell porous structure.

[0076] The protective coating may comprise a carbon nanotube network having a three-dimensional open-cell porous structure comprising a lithophilic metal oxide.

[0077] The carbon nanotube network may have a top layer of lithiphobic carbon nanotubes and a bottom layer of lithophilic metal oxide-carbon nanotube composite material.

[0078] The lithophilic metal oxides may include zinc oxide, iron oxide, manganese oxide, and titanium oxide.

[0079] The lithium alloying metal may be a low melting point metal selected from indium, tin, bismuth, gallium, silver, gold, zinc, aluminum, platinum, germanium, and field metals.

[0080] In another embodiment, the lithium metal battery negative electrode The electrode includes a metal current collector and a three-dimensional network structure coated on the metal current collector, the three-dimensional network structure being a metal-based structure or a carbon-based structure.

[0081] The aforementioned negative electrode The electrode may further include a lithium metal layer formed on the surface of the three-dimensional network structure.

[0082] In one embodiment, a lithium metal battery negative electrode The method for manufacturing the electrode includes the steps of providing a lithium metal layer on a current collector, forming a protective coating having a three-dimensional open-cell porous structure on the lithium metal layer, and forming a lithium alloy metal layer on the surface of the protective coating, wherein at least one of the two steps of forming the protective coating and forming the lithium alloy metal coating includes light electromagnetic energy irradiation.

[0083] The step of forming a protective coating comprises:

[0084] The method includes the steps of preparing a slurry containing a first polymer, a mixture of a second polymer having a boiling point lower than that of the first polymer, a conductive carbon additive, a structure-supporting additive, and a solvent; applying the slurry onto a lithium metal layer and drying to form an intermediate coating; forming a protective coating using a thin film coating; and irradiating the intermediate coating with light electromagnetic energy to evaporate the second polymer in the intermediate coating to form nanopores.

[0085] The first polymer and the second polymer may be selected from polyacrylonitrile (PAN), polytetrafluoroethylene (PTFE), poly(methyl methacrylate) (PMMA), poly(3,4-ethylenedioxythiophene)polystyrenesulfonate (PEDOT:PSS), polydiacetylene (PDA), polypropylene, polystyrene (PS), polyurethane (PU), polyethylene oxide (PEO), polyethylene terephthalate (PET), styrene-ethylene-butylene-styrene (SEBS), glycerol, sucrose, cellulose, and lignin. The conductive carbon additive may be selected from single-walled carbon nanotubes (SWCNTs), multi-walled carbon nanotubes, graphene, graphene oxide, graphene nanoplatelets (GNPs), and carbon dots. The structural support additive may be selected from hexagonal boron nitride (hBN), silicon nanowires (SiNWs), and alumina.

[0086] The step of forming the protective coating includes the steps of preparing a nanofiber precursor solution, electrospinning the nanofiber precursor solution to prepare a polymer nanocomposite nanofiber mattress, applying optical electromagnetic energy to the polymer nanocomposite nanofibers to carbonize the polymer nanocomposite nanofibers to form a carbon nanofiber mattress, and annealing the carbon nanofiber mattress with lithium metal. negative electrode and attaching the

[0087] The nanofiber precursor solution may include a polymer, a conductive carbon additive, and a solvent. The polymer may include one or more of polyamide (PA), polyacrylamide (PAAm), polyurethane (PU), polybenzimidazole (PBI), polycarbonate (PC), polyethylene (PE), polyacrylonitrile (PAN), poly(methyl methacrylate) (PMMA), polydiacetylene (PDA), polypropylene (PP), polystyrene (PS), polyethylene oxide (PEO), polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polyvinyl chloride (PVC), polyvinylpyrrolidone (PVP), collagen, and cellulose acetate (CA). The conductive carbon additive may be single-walled carbon nanotubes (SWCNTs), multi-walled carbon nanotubes, graphene, graphene oxide, graphene nanoplatelets (GNPs), and carbon dots. The solvent may include one or more of water, acetone, formic acid, chloroform, isopropanol, N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethylsulfoxide (DMSO), and tetrahydrofuran (THF).

[0088] The step of attaching the carbon nanofiber mattress includes the step of simultaneously applying thermal stress and compressive stress to attach the carbon nanofiber mattress to the lithium metal layer, and the thermal stress and compressive stress may be applied by a rolling mill, a compression molding machine, or a hot press.

[0089] The step of forming the protective coating comprises the steps of mixing a nanocomposite precursor of a lithophilic metal oxide and a lithiphobic carbon nanotube in a solvent;

[0090] The method includes depositing a nanocomposite of a lithophilic metal oxide and lithiphobic carbon nanotubes on a lithium metal layer using a thin film coating method, and applying optical electromagnetic energy to form a carbon nanotube network with gradient lithophilic-lithiphobic properties, wherein the carbon nanotube network has a top layer of lithiphobic carbon nanotubes and a bottom layer of the lithophilic metal oxide-carbon nanotube composite.

[0091] Forming the lithium alloy metal coating may include depositing powdered lithium alloy metal on the protective coating using a rolling process to place the powdered lithium alloy metal into the protective coating, irradiating the powdered lithium alloy metal with light electromagnetic energy to melt the powdered lithium alloy metal, and then applying the molten lithium alloy metal to the surface of the protective coating using capillary action.

[0092] The method may further include using sandblasting to form an engineered surface texture on the lithium metal layer.

[0093] In another embodiment, the lithium metal battery negative electrode The method for manufacturing an electrode includes the steps of forming a slurry consisting of one or more of a mixture of metal nanoparticle precursors, conductive carbon additives, polymer carriers, and a solvent, depositing the slurry on a metal current collector using the thin film coating method, irradiating it with optical electromagnetic energy to sinter the deposited slurry, and sintering the slurry after irradiating it with optical electromagnetic energy to form a three-dimensional metal-based network structure.

[0094] The metal nanoparticle precursor may include a copper-based nanoparticle precursor, and the copper-based nanoparticle precursor may be one or more selected from copper, copper acetate, copper oxide, and copper formate tetrahydrate.

[0095] The method may further include plating lithium onto a metal current collector having a three-dimensional metal-based network structure.

[0096] In another embodiment, the lithium metal battery negative electrode The electrode fabrication method includes the steps of mixing a carbon precursor, a conductive carbon additive, and a solvent to prepare a slurry, depositing the slurry on a metal current collector using the thin film coating method, and applying optical electromagnetic energy to the deposited slurry to carbonize the slurry and form a three-dimensional carbon-based network structure.

[0097] The carbon precursor may be selected from asphaltenes, mesophase pitch, cellulose, cellulose nanocrystals, and lignin.

[0098] The method may further include plating lithium onto a metal current collector having a three-dimensional carbon-based network structure. [Brief explanation of the drawings]

[0099] [Figure 1] FIG. 1 shows a schematic diagram of an engineered surface texture of a lithium metal layer formed by sandblasting and forming a protective coating. [Figure 2a-2b] 2A and 2B show schematic diagrams of a method for forming a polymer nanoporous composite coating on a lithium metal layer: Figure 2a shows a lithium foil coated with a slurry, and Figure 2b shows the polymer nanoporous composite coating formed on the lithium metal layer by applying optical electromagnetic energy. [Figure 3a-3b] Schematic diagrams of a method for forming a three-dimensional structure of carbon nanotubes on a lithium metal layer are shown in Figure 3a, which shows a coating comprising carbon nanotubes and metal oxide formed on a lithium metal layer, and Figure 3b, which shows a complex three-dimensional network of carbon nanotubes and metal oxide formed by exposure to optical electromagnetic energy. [Figure 4] 1 shows a schematic diagram of a lithium metal foil or metal current collector cooling system. [Figure 5a-5b] FIG. 1 is a schematic diagram of a method for forming a copper-silver-carbon three-dimensional structure on a current collector. [Figure 6]FIG. 1 shows a schematic diagram of one example of how the lithium metal layer can be coated with a lithium alloying metal to improve lithium ion affinity and stabilize the SEI. [Figure 7] A schematic diagram of one example of how the three-dimensional structure can be coated with lithium alloying metal to improve lithium ion affinity and stabilize the SEI is shown. [Figure 8a-8b] Schematic of the porosity of porous nanocomposite thin film samples. Scanning electron microscope (SEM) images show sample thicknesses of (a) 70 μm and (b) 100 μm. [Figure 9] FIG. 1 shows a schematic representation of the porosity of porous nanocomposite thin film samples obtained from gas pycnometer analysis. [Figure 10] FIG. 1 shows a schematic diagram of a symmetrical battery configuration for analyzing the stability of the lithium metal anode of the porous nanocomposite thin film samples. [Figure 11a-11b] Schematic diagram of the analysis results of the stability of lithium metal anodes for porous nanocomposite thin film samples with different thicknesses (70 μm and 100 μm). [Figure 12a-12b] 1 shows a schematic diagram of a comparison of the surface morphology of a copper-based metallic conductive ink before and after exposure to optical electromagnetic energy. DETAILED DESCRIPTION OF THE INVENTION

[0100] BRIEF DESCRIPTION OF THE DRAWINGS Several aspects according to the present disclosure are explained in detail with reference to the drawings, by way of example and not by way of limitation.

[0101] This disclosure proposes a novel method for suppressing lithium dendrite growth by forming three-dimensional structures primarily using photoelectromagnetic energy irradiation, such as intense pulsed light (IPL). By depositing materials onto a substrate using methods such as casting and then irradiating them with photoelectromagnetic energy, these procedures can be applied to current mass-production battery processes using roll-to-roll processes. The process proposed in this disclosure is advantageous because it is shorter and more energy-efficient than other processes described below. The material coating absorbs the photoelectromagnetic energy after irradiation to form three-dimensional structures. Furthermore, the short exposure to photoelectromagnetic energy prevents waste heat from being transferred from the coating to the lithium metal, avoiding performance degradation due to direct heating of the lithium metal substrate. Furthermore, this disclosure proposes a novel cooling device to prevent thermal decomposition of the lithium metal.

[0102] As demand for lithium secondary batteries with higher energy density increases, conventional graphite negative electrode Among the various candidate materials, lithium metal negative electrode has a high theoretical capacity (3860 mAh / g), a low electrochemical potential (-3.04 V), and a low density (0.534 g / cm 3 ) and is therefore expected to be a promising material [Guo et al., 2017].

[0103] However, the scientific community has discovered that the commercialization of lithium metal batteries presents several inherent problems that directly threaten the safety of the battery [Whittingham 2004]. With repeated charge-discharge cycles, lithium metal rapidly forms lithium dendrites. These dendrites often fracture, forming irreversible lithium fragments in the electrolyte and reducing battery capacity. In more severe cases, the lithium dendrites can sharpen and penetrate the separator, causing a short circuit, potentially resulting in a fire or even an explosion.

[0104] Furthermore, the low electrochemical potential of lithium metal is a double-edged sword: while it provides higher voltages in batteries, it is also reactive with any organic electrolyte. positive electrode They also react with products generated from the materials (such as polysulfides in lithium-sulfur batteries). These reactions are irreversible, increasing the battery impedance, reducing the total capacity, and increasing the degradation rate of lithium metal batteries [Li et al., 2019]. In addition to the above issues, the large volume change of lithium metal during lithiation cycling, the consumption of electrolyte, and the unstable solid electrolyte interface (SEI) layer also contribute to the degradation of lithium metal. negative electrode This causes deterioration of the

[0105] lithium metal negative electrode To address the issues associated with lithium metal oxides, it is desirable to apply a protective coating. negative electrode We provide three different protective coatings for the lithium metal and one for the current collector. The protective coatings have a three-dimensional open-cell nanoporous structure, but are made of different materials. However, the manufacturing processes are similar, and the process used can be easily adapted to roll-to-roll manufacturing processes, including optical electromagnetic energy application technology. negative electrode An example for producing a protective coating for is described in detail below.

[0106] Sandblasting of lithium metal anodes

[0107] lithium metal negative electrode Lithium metal with engineered surface texture before applying a protective coating to negative electrode It is preferable to fabricate the surface. Engineered surface textures may be created on the lithium metal surface by a variety of methods, including processes such as sanding, machining, microneedling, femtosecond laser, or sandblasting. The microstructures created by these processes increase the contact surface area, improve adhesion of coating materials, reduce contact resistance, and enhance ion diffusion rates (see Figure 1).

[0108] Figure 1 shows the structure of a lithium metal battery. negative electrode 1 shows a schematic representation of a blasting process for forming an engineered surface texture 115 on a lithium metal layer 110 applied to an electrode. In this disclosure, the lithium metal layer is generally lithium metal. negative electrode 1 also shows a schematic diagram of an example of a protective coating 120 formed on a lithium metal layer 110a having an engineered surface texture.

[0109] Sandblasting utilizes a stream of abrasive particles impinging on a target surface to produce wear and surface deformation. The shape, size, hardness, velocity, and contact angle of the abrasive particles determine the effectiveness of the sandblasting process. The final velocity of the abrasive is controlled by the amount of pressure applied by the pump, the type of nozzle, and the distance from the target surface.

[0110] The abrasive particles may include, but are not limited to, alumina, crushed silica, and chemically inert soda-lime glass beads. The average diameter of the abrasive particles may range from 500 nm to 10 μm. In this example, the abrasive particles used are spherical, and the carrier gas used must be an inert gas, rather than the commonly used compressed air, to minimize chemical reactions between the lithium metal and moisture.

[0111] In this exemplary embodiment, the average surface roughness R a The lithium metal surface with a roughness of 1 to 100 μm is produced using sandblasting. a This can be achieved using a series of different process parameters. In one example, alumina particles with an average diameter of 50 μm are sprayed with compressed argon gas at 80 psi with a contact angle of 15°. The blasting area is 2 cm in diameter and the blasting speed to the surface is 1 cm / s, and the process is repeated twice. Sandblasting is performed in a glove box filled with argon gas, with the humidity in the glove box at 0.1 ppm. A contact profiler (Mitutoyo SJ.201P) is used to measure 10 different points on the surface, and the lithium metal negative electrode Average surface roughness R a The average value of the measured surface roughness R a is 67.4 μm.

[0112] The sandblasting process increases the contact surface, improves the adhesion of the conductive protective coating 120, and reduces the interfacial resistance. negative electrode 110, forming a roughened surface, i.e., an engineered surface texture 115 thereon.

[0113] Protective coating with three-dimensional open-cell foamed structure

[0114] The development of protective coatings with a three-dimensional open-cell porous structure can address diverse application needs. First, the complex structure provides abundant nucleation points, allowing lithium to be uniformly plated at these nucleation points, rather than lithium dendrites growing intensively at a few nucleation points. Second, the surface area of ​​a three-dimensional structure is much larger than that of a flat surface, allowing lithium metal to be deposited evenly. negative electrode This reduces the local current density in the electrode, slowing dendrite growth [Monroe and Newman 2005]. Furthermore, submicron structures induce uniform charge distribution, reducing dendrite growth [Yang et al. 2015].

[0115] The low density of the three-dimensional open-cell foam structure also contributes to stress relief due to the volume expansion of lithium metal. negative electrode This occurs within the protective coating of the three-dimensional structure without increasing the volume of the structure. Whether the deformation is internal or external due to volume change, the three-dimensional structure can mechanically absorb the deformation without generating additional stress.

[0116] In this example, three different protective coatings with three-dimensional open-cell foamed microstructures are described, including a nanoporous polymer nanocomposite coating, a carbon nanotube network with a metal oxide coating, and a carbon fiber mattress.

[0117] Nanoporous polymer nanocomposite coatings

[0118] Polymer materials are suitable for lithium metal due to their material properties and ease of handling. negative electrode Polymeric materials are commonly used in various parts of lithium-ion batteries, such as separators, electrode binders, and polymer gel electrolytes in solid-state lithium batteries. Polymers may have different properties depending on their components, structure, and functional groups.

[0119] lithium metal negative electrode The polymers for coating the electrode are electrochemically stable to both lithium metal and electrolyte, homogenize the flux of lithium ions near the electrode surface, inhibit the formation of lithium dendrites, reduce direct contact between the lithium metal and the electrolyte, and maintain contact with the electrode even during large volume changes. Furthermore, the polymers can be applied to lithium metal using conventional methods such as spin coating, spray coating, coating, and doctor blade deposition. negative electrode The polymer can be easily applied to the substrate. The simple application method ensures the efficiency of large-scale processing and makes it easy to control the coating thickness.

[0120] lithium metal negative electrode Examples of polymeric materials for application to the electrode may include one or more of polyethylene oxide (PEO), polyethersulfone (PES), poly(dimethylsiloxane) (PDMS), poly(ethylene-vinyl alcohol-β-acrylonitrile ether) (EBC), polyvinyl alcohol (PVA), and polydopamine (PDA). The above polymers have polarity (e.g., oxygen groups in PEO, cyano groups in EBC, and hydroxyl groups in PVA), which allows for strong electrostatic interactions with lithium ions.

[0121] Even without a three-dimensional structure, poly(dimethylsiloxane) (PDMS) thin films [Zhu et al., 2017] and other high-viscosity polymers can effectively transport lithium metal during lithiation cycling. negative electrode Furthermore, polyethylene oxide (PEO) coatings have been used to stabilize lithium metal. negative electrode showed that stable polar oligomers are formed during the first electrochemical cycle, resulting in a stabilized SEI layer [Assegie et al., 2018].

[0122] lithium metal negative electrode Another interesting example of a polymer coating is the use of polyvinylidene fluoride (PVDF) in the β phase. PVDF in the β phase has ferroelectric properties due to its unique crystalline structure, and is sensitive to stress (i.e., lithium metal). negative electrode The piezoelectric potential is generated in the coating by the action of the stress due to the volume expansion of the battery. The piezoelectric potential acts as a lithium ion pump, promoting the diffusion of lithium ions on the coating, thereby improving the charging speed and uniformity of the lithium ion flux [Xiang et al., 2019].

[0123] 2a and 2b show schematic diagrams of a method for forming a polymer nanoporous composite coating on a lithium metal layer: Fig. 2a shows a lithium foil coated with a slurry, and Fig. 2b shows the polymer nanoporous composite coating formed on the lithium metal layer by applying optical electromagnetic energy.

[0124] In this example, the lithium metal battery negative electrode The lithium metal layer 110 applied to the electrode may be a lithium foil. The lithium metal layer 110 is provided on a metal current collector (e.g., a copper current collector). The slurry mixture includes a first polymer 121 with a high boiling point, a second polymer 122 with a lower boiling point than the first polymer 121, and a conductive carbon additive 123. The slurry is deposited on the lithium metal layer 110 and dried in a vacuum oven to form a coating 120 (see FIG. 2a).

[0125] Furthermore, optical electromagnetic energy can be applied by an IPL irradiation device 201 to heat the coating 120 and evaporate the low-boiling point second polymer 121. This process ultimately leaves nanopores 122a in the polymer nanocomposite, forming an open-cell porous structure with interconnected voids via the nanopores 122a (see FIG. 2b).

[0126] In this example, a novel fabrication method is proposed to form a nanocomposite coating with an open-cell porous structure on a lithium metal layer 110. This method utilizes the rapid evaporation of a low boiling point material within the protective coating 120 to form the open-cell porous structure. The nanocomposite coating consists of a primary polymer matrix, a conductive carbon additive, a structural support additive, and a second polymeric material with a significantly lower boiling point than the primary polymer.

[0127] The main polymer (first polymer) matrix is ​​the main body of the porous membrane structure. The boiling point of the second polymer is very low, and during rapid evaporation, the second polymer is released from the thin film under the action of light electromagnetic energy, thereby creating voids. Examples of polymers used as the first and second polymers include polyacrylonitrile (PAN), polytetrafluoroethylene (PTFE), poly(methyl methacrylate) (PMMA), poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), polydiacetylene (PDA), polypropylene, polystyrene (PS), polyurethane (PU), polyethylene oxide (PEO), polyethylene terephthalate (PET), styrene-ethylene-butylene-styrene (SEBS), glycerol, sucrose, cellulose, or lignin. Among these, multiple polymers with a difference in boiling point of 10°C or more or 20°C or more can be selected as the main polymer and the second polymer.

[0128] Carbon-based conductive nanomaterials form conductive networks within a polymer matrix and act as absorbers of optical electromagnetic energy. Examples of carbon-based conductive nanomaterials include single-walled carbon nanotubes (SWCNTs), multi-walled carbon nanotubes, graphene, graphene oxide, graphene nanoplatelets (GNPs), or carbon dots.

[0129] The structural support additives are materials with high mechanical strength and electrochemical inertness. The additives can improve the mechanical strength and durability of porous polymer nanocomposites. Examples of structural support additives include hexagonal boron nitride (hBN), silicon nanowires (SiNW), and alumina.

[0130] The above components are mixed with a suitable solvent for the polymer used in the blend to form a slurry, which is then coated with lithium metal using a thin film coating technique (e.g., doctor blade coating, bar coating, spray coating, or solution casting). negative electrode The slurry is applied to the surface of the substrate to form a thin film. The thin film is then dried in a vacuum oven. The dried thin film is then irradiated with light electromagnetic energy to rapidly evaporate the low-boiling second polymer, allowing the evaporated gas to escape from the thin film, forming an open-cell porous structure.

[0131] Metal oxide-containing CNT network

[0132] Carbon conductive materials are widely used in various fields due to their high electrical conductivity and mechanical strength. Among the carbon conductive materials, carbon nanotubes (CNTs) are known for their high aspect ratio due to their nanometer diameter and micrometer length. This three-dimensional structure of CNTs has the properties of a high aspect ratio, high electrical conductivity, and lithium-phobic material, making them suitable for transporting lithium metal. negative electrode A suitable interfacial layer can be formed on the surface of the electrode, preventing the formation of lithium dendrites and promoting the diffusion of lithium ions while forming a stable SEI layer.

[0133] However, due to the lithium-phobic nature of CNTs, it is difficult to convert CNT-based structures into lithium metal. negative electrode Zhang et al. [Zhang et al., 2018] proposed a lithium metal interfacial layer with a gradient of lithophilic-lithiphobic properties. negative electrode reported that CNTs containing various zinc oxides (ZnO) were dropped layer by layer onto a lithium foil to form a lithophilic bottom layer and a lithophobic top layer. The gradient lithophilic-lithophobic layer applied to the lithium metal foil was compared to a lithium metal foil coated with CNTs alone. Compared to the lithium metal foil coated with CNTs alone, the gradient lithophilic-lithophobic layer exhibited a current of 1 mA cm. -2 In symmetric cell tests, the lithium foil samples showed higher cycling stability at a constant current density of 1000 kJ / s. negative electrode and positive electrode The CNT-only sample was placed in a button cell as both a lithophilic and a lithiphobic layer. The CNTs were then cycled at a constant current density, maintaining a constant charge-discharge voltage amplitude. An increase in the voltage amplitude was observed, indicating the onset of lithium dendrite formation within the cell. The gradient lithophilic-lithiphobic layer exhibited stability over cycle times up to 500 hours, while the CNT-only sample showed instability with an increasing voltage amplitude after 200 hours of cycle time.

[0134] A gradient lithophilic-lithiphobic interfacial layer is a viable method for suppressing lithium dendrite growth in lithium metal batteries. However, the method proposed by Zhang et al. requires a complex fabrication process. For example, to form a gradient layer, solutions of CNTs and zinc oxide with varying concentrations must be prepared. These are deposited layer by layer on the lithium foil, which requires a drying process between the two depositions of each layer, thereby increasing the fabrication time. The low melting point of lithium metal (180 °C) means that the solvent cannot be dried rapidly at high temperatures.

[0135] FIG. 3 shows a schematic diagram of a method for forming a three-dimensional structure of carbon nanotubes on a lithium metal layer.

[0136] In this embodiment, the lithium metal layer 310 may be a lithium foil. A slurry containing a solvent 321, randomly dispersed carbon nanotubes 325, and a metal oxide is deposited on the surface of the lithium metal layer and dried in a vacuum oven to form a coating 320 (see FIG. 3a).

[0137] IPL light electromagnetic energy irradiation heats the coating 320, evaporating the solvent 321 and leaving behind an intricate three-dimensional network of interconnected carbon nanotubes 325a and metal oxides 322 (see FIG. 3b).

[0138] This disclosure proposes a novel method for utilizing optical electromagnetic energy. The lithophilic-lithiphobic layer gradient is formed by the effect of optical electromagnetic energy rather than by layer-by-layer deposition. Instead of using multiple solutions containing varying concentrations of CNTs and zinc oxide, a slurry mixture of CNTs, metal oxide, a small amount of polymer binder, and solvent is deposited on a lithium metal foil and then irradiated with optical electromagnetic energy. The optical electromagnetic energy evaporates the polymer coating, reducing the metal oxide in the top layer and leaving a lithiphobic CNT layer on top. Because the irradiated optical electromagnetic energy is applied from above, less energy is transmitted deep into the coating slurry, leaving the lithophilic metal oxide and polymer binder in the bottom layer.

[0139] The lithophilic metal oxide may include, but is not limited to, one or more of zinc oxide, iron oxide, manganese oxide, and titanium oxide. The carbon nanotubes may include, but are not limited to, single-walled CNTs (SWCNTs), double-walled CNTs (DWCNTs), multi-walled CNTs (MWCNTs), functionalized CNTs, or short carbon nanofibers. The solvent may include, but is not limited to, water, ethanol, hexane, N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethyl sulfoxide (DMSO), or a combination thereof.

[0140] FIG. 4 shows a schematic of a lithium metal foil or metal current collector cooling system.

[0141] The cooling system shown in Figure 4 illustrates the transfer of waste heat that may accumulate in the lithium metal layer 110 or metal current collector in Figures 2b and 3b during exposure to light electromagnetic energy.

[0142] The cooling system includes a holder plate 401 with a thermally conductive metal, a refrigerant inlet 410 provided on one side of the holder plate, a heat exchange flow path 420 extending from the refrigerant inlet into the holder plate, and a refrigerant outlet 430 provided on one or the other side of the holder plate and connected to the heat exchange flow path 420.

[0143] The holder plate 401 is a holder for a lithium metal battery of a specific size. negative electrode The metal plate includes a metal plate with an extruded fixing means to fit the heat exchanger system, the metal plate having a thickness sufficient to fix the heat exchanger system, and the material of the metal plate may include, but is not limited to, copper and aluminum.

[0144] The coolant inlet 410 and outlet 430 can be connected to a coolant pump, etc. The Peltier element may also be replaced with a heat exchange passage through which the coolant flows.

[0145] A coolant such as cooling water passes through the heat exchange passage 420 made of a highly thermally conductive material. negative electrode Aluminum in contact with lithium metal is irradiated with light and electromagnetic energy. negative electrode It can remove excess heat absorbed by the

[0146] Carbon nanofiber / fiber mat less

[0147] Carbon fiber mattress is made of lithium metal negative electrodeIt is another porous carbon structure suitable for lithium ion batteries, which can suppress the formation of lithium dendrites and provide the necessary space for lithium deposition during charging. Carbon fiber manufacturing is a relatively mature process. However, long processing times and high-temperature heating are usually required to stabilize and carbonize the carbon precursor material. High-temperature processing allows the fabrication of a carbon fiber mattress alone, which can then be used to transport lithium metal. negative electrode The temperatures and pressures required to bond a carbon fiber mattress to lithium metal are typically below the melting point of lithium metal (180.5°C).

[0148] In 2017, Liu et al. reported that by carbonizing commercially available cotton, lithium metal negative electrode The hollow carbon fiber structure was formed on the surface of the carbon fiber. Lithium deposition was observed to occur on the outer surface of the carbon fiber, filling the gaps between the fibers, and on the inner surface of the carbon fiber, filling the hollow spaces inside the carbon fiber. By maximizing the surface area and porosity, the hollow carbon fiber structure was able to accommodate the lithium metal coating. negative electrode showed stability for over 600 cycles in symmetrical battery tests, whereas bare lithium foils began to become unstable after 180 cycles under the same conditions [Liu et al., 2017]. Another study conducted by Zhang et al. involved coating carbon fibers with lithophilic silver by plating silver directly onto the fibers. This facilitated lithium incorporation and resulted in lithium metal with stability similar to that of pure lithium metal. negative electrode was obtained [Zhang et al., 2017].

[0149] The present disclosure provides a method for reducing dendrite growth and maintaining stability by using lithium metal negative electrodeWe propose a novel method for forming three-dimensional carbon fiber structures on a substrate. This method uses optical electromagnetic energy irradiation for carbonization, improving energy efficiency and shortening processing time. To compensate for the lack of energy penetration depth, polymer nanocomposite nanofibers containing carbonaceous nanoparticles can be produced by electrospinning. The small diameter of nanofibers and the high energy absorption rate of carbonaceous nanoparticles lower the energy threshold required for carbonization.

[0150] A horizontal electrospinning apparatus can be used to spin polymer nanocomposite nanofibers. The electrospinning apparatus is connected to a needle attached to a syringe pump using a high-voltage power supply. The pump and the base of the drum are grounded. The drum rotates at a constant speed, and the base is connected to a high-resistance resistor (approximately 100 MΩ) to maximize deposition on the drum while minimizing fiber deposition elsewhere. The flow rate into the system is set to maintain a single droplet at the tip of the needle. The syringe pump is mounted on an XY platform programmed to perform an oscillating motion to deposit fibers evenly across the drum. Electrospinning is a cost-effective and convenient alternative method for producing nanoscale fibers and nonwoven mats. Electrospinning allows for control of the porosity and surface area of ​​the fiber mattress.

[0151] Electrospinning can be used to spin a mixture of polymers, carbonaceous nanocomposites, and solvents. Applicable polymers include one or more of polyamide (PA), polyacrylamide (PAAm), polyurethane (PU), polybenzimidazole (PBI), polycarbonate (PC), polyethylene (PE), polyacrylonitrile (PAN), poly(methyl methacrylate) (PMMA), polydiacetylene (PDA), polypropylene (PP), polystyrene (PS), polyethylene oxide (PEO), polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polyvinyl chloride (PVC), polyvinylpyrrolidone (PVP), collagen, and cellulose acetate (CA).

[0152] The conductive carbon additive may include one or more of single-walled carbon nanotubes (SWCNTs), multi-walled carbon nanotubes (MWCNTs), graphene, graphene oxide, graphene nanoplatelets (GNPs), and carbon dots.

[0153] The solvent may include, but is not limited to, combinations of water, acetone, formic acid, chloroform, isopropanol, N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and tetrahydrofuran (THF), depending on the polymer used.

[0154] Once electrospinning is complete, the polymer nanocomposite nanofibers can be carbonized using light electromagnetic energy. In this process, the spun fibers are carbonized using lithium metal negative electrode By placing the nanofibers on a substrate different from the one used in the previous article and applying high-intensity IPL to the spun fibers while irradiating them with light electromagnetic energy, the carbon fiber mattress can be completely carbonized from both sides. Once the polymer nanocomposite nanofibers are carbonized into a carbon fiber mattress, a hot press technique can be used under heat and pressure to add lithium metal oxide to the nanofibers. negative electrode is transcribed into

[0155] Application of photoelectromagnetic energy by intense pulsed light (IPL)

[0156] lithium metal negative electrode The most important step in forming a three-dimensional open-cell porous structure on a coating film or current collector is the energy application process. In conventional methods, the most common method is to apply thermal energy through pyrolysis, which generally requires a lot of energy and time. Furthermore, this process requires a lot of time and energy to process lithium metal. negative electrode Since it is necessary to apply energy to the coating film, the melting point of lithium metal is low (180.5°C), and thermal decomposition at high temperatures (400 to 800°C) cannot be used. negative electrode A method of applying optical electromagnetic energy (i.e., IPL, etc.) that applies energy without damaging the tissue is utilized.

[0157] Intense Pulsed Light (IPL) utilizes high-speed light electromagnetic waves generated by a xenon lamp. The xenon lamp applies high-intensity electrical pulses, which excite the xenon gas to a high-energy state and then return to a low-energy state, generating photon irradiation. Compared to other electromagnetic energy application processes such as lasers and microwaves, the advantage of IPL technology is its ability to cover large surface areas in a short time (a few milliseconds).

[0158] Furthermore, IPL has a broad pulse spectrum, typically ranging from 200 nm to 1100 nm, whereas laser and microwave technologies have more specific wavelength spectra. Modern IPL devices utilize a bank of computer-controlled capacitors to generate IPL, and the pulse duration, pulse spacing, number of pulses, and intensity are all controllable. The fluence (radiant energy received by a surface per unit area) is related to the distance from the energy source to the target surface, the angle of the reflector, and the absorption rate of the target surface.

[0159] As mentioned above, a carbon additive with high absorption over a wide spectral range is present in the mixture encapsulating the active material, converting the absorbed energy into thermal energy to form a nanoporous structure. This means that the IPL process is much more energy efficient and much faster than pyrolysis processes. Because of its energy efficiency and short processing time, this method is more suitable for mass production of batteries using existing roll-to-roll manufacturing processes.

[0160] Considering a typical IPL system, the diffusion depth of the IPL irradiation is limited to a range of about 1 μm from the surface. When processing bulk materials, this limited diffusion depth may be undesirable. However, in the present disclosure, delivering energy to a thin film is sufficient to produce the desired effect on the coating. Also, since no energy is transferred to layers below the surface or the effect on the layers below the surface is minimal, the lithium metal below the coating is not affected. negative electrode Damage to the carbon nanotubes can be avoided. The formation of a gradient lithophilic-lithiphobic layer of carbon nanotubes and metal oxides also has interesting effects, such as the generation of a gradient effect.

[0161] Anode-less copper current collector with a three-dimensional structure

[0162] The protective coating, with its three-dimensional open-cell porous structure, is designed to protect the lithium metal from excessive external stresses caused by dendrite growth and volume changes associated with lithiation cycling. negative electrode However, lithium metal negative electrode The lithiation process involves the electrodeposition of lithium ions, so the question arose as to whether a lithium metal layer was necessary. positive electrode It is the origin, negative electrode All that is required is to store lithium ions in the form of electrodeposited lithium. negative electrode The "less" current collector is the same as that of a lithium metal battery. negative electrode It can be concluded that the role of

[0163] " negative electrode For the "less" current collector to function properly, it needs a rack or structure that can store lithium ions during lithiation. This again requires the formation of a 3D open-cell foam porous structure on the current collector. The 3D open-cell foam porous structure on the current collector allows the lithium metal negative electrode It has the same advantages as the protective coating of the current collector. During lithiation cycling, it provides abundant nucleation sites and space for lithium deposition, preventing volume changes and preventing excessive internal stress. Furthermore, the large surface area of ​​the highly conductive material promotes uniform charge distribution and reduces dendrite formation. When internal or external mechanical stress is present, the three-dimensional structure of the current collector can provide structural support and absorb the stress.

[0164] negative electrode Much research has been done on the fabrication of three-dimensional structures and racks for loess current collectors, including the creation of high-roughness surfaces, chemical and mechanical etching of the current collector surface, and the construction of additional structures using polymers, metals, or carbonaceous materials.

[0165] For example, a 3D copper-carbon frame constructed on a copper current collector [Chen et al., 2020] is an example. Melamine-formaldehyde foam is pyrolyzed to form a carbon frame, which is then plated with copper to create a 3D structure. This provides good conductivity, increases surface area, provides a stable SEI, and reduces dendrites. Battery testing has shown that the battery maintains 99.85% capacity even after more than 300 cycles. However, the carbon frame requires heating at 900°C in a N2 atmosphere for 2 hours, followed by electroplating for 10 minutes using copper and CuSO4 (copper sulfate) electrolyte, which is toxic.

[0166] In another example, copper foam was fabricated as a current collector and then coated with reduced graphene oxide (rGO) [Yu et al., 2019]. In this method, the fabrication process involves immersing the copper foam in a liquid containing a graphene oxide suspension for 12 hours to obtain reduced graphene oxide (rGO) coated on the copper foam. negative electrode Half-cell tests using rGO-coated copper foam as a cathode showed that the coulombic efficiency (CE) remained above 98.5% after 350 cycles. The process is simple but requires a long processing time (12 hours) and expensive low-density copper foam.

[0167] Metallic 3D structure of current collector

[0168] This disclosure proposes a three-dimensional metal-based network structure that is realized by coating a metallic conductive ink followed by a sintering process using optical electromagnetic energy, and the three-dimensional structure is mainly composed of conductive metals and a small amount of additives.

[0169] 5 shows a schematic diagram of a process for fabricating a three-dimensional conductive metal structure on a current collector using a copper-based conductive ink as an example. In particular, FIG. 5 shows a method for forming a copper-silver-carbon three-dimensional structure on a copper current collector 510. Then, lithium plating is performed during charging, and lithium metal is deposited. negative electrode Form.

[0170] In this example, the current collector is made of copper. A conductive ink mixture is applied to the current collector and dried in a vacuum oven (see FIG. 5a). In this example, the conductive ink mixture includes, but is not limited to, a solvent carrier, copper nanoparticles 511, silver nanoparticles 512, and a conductive carbon additive 513. Different materials can be used in different ratios for specific applications.

[0171] For example, the IPL irradiation device 501 irradiates light electromagnetic energy to sinter copper nanoparticles, forming a three-dimensional conductive network consisting of copper nanoparticles 511, silver nanoparticles 512a, and conductive carbon additives 513 on the current collector 510.

[0172] The three-dimensional conductive network formed on the current collector is itself a single negative electrode During charging, lithium is plated onto the current collector on which the three-dimensional conductive mesh is formed, forming a three-dimensional lithium metal negative electrode An electrode can be formed (see Figure 5b).

[0173] Conductive metal nanoparticles are primarily copper-based nanoparticles, including, but not limited to, pure copper nanoparticles, copper formate, copper oxide, copper nitrate, copper nitrite, copper acetate nanoparticles, and coated nanoparticles with tin or polymer protective layers. Although not conductive themselves, when exposed to a critical amount of energy, the metal nanoparticles melt instantaneously and form conductive bridges.

[0174] Polymer carriers include, but are not limited to, diethylene glycol (DEG) and / or poly(N-vinylpyrrolidone) (PVP), both of which are common conductive ink carriers. Additives are classified into two categories: metallic and non-metallic, each with a specific purpose. Protective layers and additives surround the primary metal conductor (i.e., copper nanoparticles) and fill the gaps between the nanoparticles. Additional additives may improve electrical conductivity, eliminate or inhibit oxidation, reduce the energy required for sintering, improve energy absorption, improve solderability and adhesion, ensure corrosion and wear protection, and improve self-healing properties. These additives include, but are not limited to, silver salts, tin, manganese, gallium, indium tin oxide, bismuth, zinc, lead, antimony, gold, silver, palladium, platinum, microfibers, carbon nanofibers, metal fibers, graphene, graphene nanoplatelets, and carbon nanotubes, all with various dimensional specifications.

[0175] The mixture is prepared by stirring and sonication. Because the solvent and carrier polymer cannot dissolve some of the primary materials, sonication using ultrasonic frequencies is necessary to improve the dispersion of the materials. After the conductive ink mixture is prepared, it can be applied to the current collector by various coating methods (including, but not limited to, bar coating, spray coating, doctor blade coating, etc.). Once the mixture is applied, the remaining solvent is evaporated and removed by low temperature (<50°C) vacuum drying.

[0176] The deposited conductive ink particles form a loose layer with gaps between the conductive metal particles, so they are not immediately conductive in their dry state. The application of energy (typically in the form of heat) can partially melt the nanoparticles, forming conductive bridges between them. Nanoparticle sintering techniques include both conventional and pioneering techniques.

[0177] Conventional metal nanoparticle sintering methods require an inert gas environment at 150°C to 300°C. Furthermore, creating such a temperature and gas environment takes time, and requires expensive equipment and a base that can withstand high temperatures. Due to these conditions, conventional sintering methods cannot be expected to be practically effective.

[0178] In this disclosure, metal particles are sintered by applying optical electromagnetic energy. Optical electromagnetic energy application methods include irradiation with one or more of IPL (intense pulsed light), laser, IR (infrared light), and microwave. Optical electromagnetic energy application methods have several advantages over traditional pyrolysis or thermal application. Most importantly, optical electromagnetic energy application ensures higher energy efficiency. While other heating methods require increasing the temperature of the entire heating chamber, optical electromagnetic energy application differs from applying energy directly to the target surface. Furthermore, adding a carbon additive can further improve energy absorption efficiency and reduce power consumption.

[0179] Furthermore, optical electromagnetic energy application methods involve only short-term energy exposure. IPL methods utilize the flash of a xenon lamp and can cover large surface areas in just a few milliseconds. While laser and microwave methods can take several seconds per irradiated area, roll-to-roll manufacturing processes can achieve high delivery throughput. Although the power required may be high, the total amount of energy required is much lower than traditional thermal application processes due to the short processing time. Most importantly, optical electromagnetic energy application methods do not require any chamber or inert environment, making them compatible with existing negative electrode There is no need to significantly modify the manufacturing equipment.

[0180] Fabrication of carbon-based three-dimensional structures on copper current collectors using industrial by-products

[0181] Carbon has the characteristics of high conductivity, a hard structure, and the ease of forming three-dimensional structures. negative electrode This makes it an ideal material for fixing the three-dimensional structure of the loess current collector.

[0182] Various carbon sources are being considered as potential candidates. For example, Aruna Zhamu and Bor Z. Jang of the Universal Graphene Group have proposed a novel method for fabricating a graphene-based nanotube with a lithium metal layer and a porous conductive layer of graphene. negative electrode The porous conductive layer increases the surface area for lithium deposition, forming a stable SEI and reducing the formation of lithium dendrites. negative electrode The technology also results in more uniform conductivity and fewer lithium dendrites. This technology uses lithium metal to prevent dendrite growth and catastrophic failure. negative electrode The method involves applying a basic three-dimensional structure to a substrate, but does not include an efficient manufacturing process for forming the structure.

[0183] As another example, Zhaohui Liao, Chariclea Scordilis-Kelley, and Yuriy Mikhaylik have reported on lithium metal ion exchange reactions that can produce uniformly dispersed lithium alloys and / or lithium nitrides. negative electrodeIn 2012, we proposed a porous protective layer for lithium ions, which can improve the diffusion ability of lithium ions and prevent the formation of lithium dendrites. This method uses cost-effective materials to form a porous protective layer for lithium metal. negative electrode The protective layer is formed by coating the substrate with a slurry and then drying the coating. The protective layer material is composed of a metal compound, a conductive agent, and a binder, and the metal compound may be a metal nitride, alumina, or aluminum fluoride. This method involves the formation of a porous structure, but is limited to the slurry deposition and drying steps. Furthermore, the drying step takes 720 hours, making it time-inefficient.

[0184] Other promising carbon precursors for porous carbon structures are industrial by-products such as asphaltenes, pitches, cellulose, and lignin. Asphaltenes, an industrial by-product of crude oil, are often removed due to their high viscosity and carbon content, which negatively impact fuel production and energy efficiency. Asphaltenes have been treated as waste materials from the oil and natural gas industry, they are cheap and in abundant supply. The use of asphaltenes to produce advanced lithium-ion batteries offers economical and environmentally friendly advantages. Pitch is a high-carbon industrial by-product extracted from petroleum, coal tar, or wood. Cellulose and lignin are high-carbon materials found in plants and agricultural and forestry by-products such as rice husk, wheat, straw, and sawdust.

[0185] The benefits of asphaltenes, which form three-dimensional structures on current collectors as a carbon source, have also been discovered. Wang et al. fabricated high-capacity lithium metal batteries with ultrafast charging capabilities using asphaltenes [Wang et al., 2017]. In this study, untreated hard pitch was used as the carbon precursor. Hard pitch is a naturally occurring, black, solid, lightweight material with a high asphaltene content. The untreated hard pitch was pretreated at 400°C under argon gas for 3 hours and then ground in a mortar with potassium hydroxide (KOH). The mixture was heated at 850°C for 1 hour, filtered, washed with water, and dried at 110°C for 12 hours. The KOH mixture, pretreated hard pitch, graphene nanoribbons (GNRs), and polyvinylidene fluoride (PVDF) were mixed in a mortar in a mass ratio of 4.5:4.5:1, and then N-methyl-2-pyrrolidone (NMP) solvent was added to form a slurry. This slurry was applied to a copper foil and then dried overnight in vacuum at 50 °C to form Asp-GNR-Li negative electrode This results in a high-porosity carbon structure called

[0186] Asp-GNR-Li negative electrode is a conventional copper lithium negative electrode Furthermore, repeated charge-discharge cycles at a constant current density of 0.5 C revealed that the Asp-GNR-Li negative electrode can maintain 90% of its specific capacity after 130 cycles, while conventional copper-lithium negative electrode The specific capacity of the conventional copper lithium battery decreased to less than 75% after 130 cycles. negative electrode This shows that the specific capacity of

[0187] The idea of ​​using high-carbon asphaltenes as precursors to carbon structures is very promising, especially because they are cost-effective and in abundant supply. However, the production process proposed in Wang et al.'s study involves many steps and requires high temperatures and long processing times.

[0188] The present disclosure provides a method for manufacturing a porous carbon substrate having a porous carbon structure on a copper foil. negative electrode We propose a new manufacturing technology that utilizes optical electromagnetic energy irradiation to form a non-metallic current collector. As mentioned above, the optical electromagnetic energy application method has the advantage of saving energy and time compared to the conventional heating process using a melting furnace. The optical electromagnetic energy application method does not require any melting furnace, chamber, or inert environment, and can be readily applied to mass production processes involving a roll-to-roll process.

[0189] In this method, a slurry mixture of a carbon precursor, a conductive carbon additive, and a solvent is prepared. The carbon precursor includes high-carbon industrial by-products such as asphaltene, mesophase pitch, cellulose, cellulose nanocrystals, and lignin. The conductive carbon additive increases structural rigidity, improves electrical conductivity, and increases the energy absorption of light-based electromagnetic energy. These additives include one or more combinations of carbon black, single-walled carbon nanotubes, multi-walled carbon nanotubes, functionalized carbon nanotubes, graphene, and graphene nanoplatelets. The slurry mixture is deposited on a copper foil using a thin-film coating method. After drying the slurry on the copper foil, light-based electromagnetic energy is applied to carbonize the slurry and form a three-dimensional carbon-based network. During charging, lithium is plated onto the surface of the three-dimensional carbon-based network.

[0190] Low melting point lithium alloy metal coating

[0191] The addition of a low-melting-point lithium alloy metal coating contributes to the stabilization of the solid electrolyte interface (SEI) layer. Such a metal coating can be used as a lithium metal layer, a protective layer, or a negative electrode The SEI layer can be stabilized by utilizing three distinct properties: high electrical conductivity, rapid alloying reaction with lithium ions, and self-healing.

[0192] Lithium alloy metals often have higher electrical conductivity than copper or silver. By applying this to the lithium metal layer, the electrolyte negative electrode This reduces the contact resistance with lithium metal and improves the charge transport rate. negative electrode When indium is applied to the negative electrode It was found that the electrical contact resistance between the electrodes significantly decreased [Choudhury et al., 2017].

[0193] Research has also shown that indium facilitates the rapid diffusion of lithium ions through surface diffusion. Density functional theory calculations indicate that indium provides fewer diffusion barriers at the surface. Lithium ions bind loosely to the indium plating layer and rapidly pass through it to be deposited on the underlying lithium metal layer [Choudhury et al., 2017]. Rapid ion conduction can also reduce dendrite formation.

[0194] Finally, metals such as indium have the ability to self-heal, maintaining the SEI during cycles of volume change due to lithiation and delithiation. In a liquid electrolyte environment, metal plating can be performed by adding trace amounts of metal salts to the electrolyte, and damaged metal plating layers can be repaired during the process. This is possible because indium is inert to common electrolytes, preventing side reactions and allowing the battery to maintain more than 90% of its original energy capacity after 250 charge-discharge cycles [Choudhury et al., 2017].

[0195] In a solid electrolyte environment, the lithium alloy metal coating utilizes its low melting point to self-heal. The field metal is an alloy of bismuth, indium, and tin, each of which has a relatively high melting point (271.4°C, 156.6°C, and 231.9°C), while the alloy melts at only 62°C. The low melting point allows the metal coating to self-heal by either passively utilizing heat generated by the battery's internal resistance or actively utilizing the battery's Joule heating system (commonly used to control the battery's temperature in cold environments). This self-healing ability maintains the stability of the SEI layer, reduces dendrites, and preserves the electrolyte and active materials during repeated charge-discharge cycles.

[0196] FIG. 6 shows a schematic diagram of an example of a method for applying a lithium metal layer using a lithium alloying metal to improve lithium ion affinity and stabilize the SEI. As shown in FIG. 6, a crushed lithium alloying metal powder 620 is placed directly on top of the lithium metal layer 610. The lithium alloying metal powder is then sintered by irradiation with optical electromagnetic energy. The flash sintering process converts the partially molten lithium alloying metal into lithium metal. negative electrode The surface of 610 can be uniformly coated to form a lithium alloy metal coating 620a.

[0197] 7 shows a schematic example of a method for coating a three-dimensional structure with a lithium alloy metal to improve lithium ion affinity and stabilize the SEI. As shown in FIG. 7, a crushed lithium alloy metal powder 620 is placed on top of a three-dimensional structure 710 that has been coated on a lithium metal layer 610. The lithium alloy metal powder 620 is then rolled to coat the three-dimensional structure 710 with the lithium metal. negative electrode The lithium alloy metal powder is applied to the three-dimensional structure 710. Light electromagnetic energy is applied to sinter the lithium alloy metal powder. The instant sintering process can uniformly apply the partially molten lithium alloy metal to the surface of the three-dimensional structure 710, forming a lithium alloy metal coating 620a.

[0198] The low melting point lithium alloy metal coating may be applied directly onto the lithium metal layer as shown in Figure 6, or may be applied onto a three-dimensional open-cell porous protective coating on the lithium metal layer as shown in Figure 7.

[0199] An example of applying a lithium alloy metal on the lithium metal layer or three-dimensional protective coating shown in Figure 7 is described below. In this example, the lithium alloy metal powder is irradiated with light electromagnetic energy to melt it in a short time while minimizing the thermal impact on the lithium metal layer underneath, and the molten lithium alloy metal powder is then applied onto the lithium metal layer or three-dimensional protective coating. This method differs from conventional hot melt dip coating or electrodeposited metal painting.

[0200] This example describes a process for forming a low-melting-point lithium alloy metal coating using a simple method that utilizes rolling, application of optical electromagnetic energy, and capillary action. First, a powdered low-melting-point lithium alloy metal is produced. Low-melting-point lithium alloy metals may include, but are not limited to, indium, tin, bismuth, gallium, silver, gold, zinc, aluminum, platinum, germanium, and eutectic alloys (e.g., field metals). Due to their high ductility, these metals and metalloids may require freeze-milling to produce a fine powder.

[0201] Metal powders can be randomly deposited on the surface of the 3D protective coating and then rolled under pressure and heat to penetrate the voids in the 3D protective coating. When light electromagnetic energy is applied, the metal powder melts and wets through the 3D structure by capillary action. This method is feasible because these metals have low melting points and do not damage the substrate (i.e., the lithium metal layer with protective layer) at the desired temperature.

[0202] To observe the lithium dendrite formation suppression effect, a sample of a three-dimensional CNT network containing metal oxide was prepared. Carboxylic acid-modified CNTs (ACNTs), zinc oxide, and PVDF were dissolved in NMP solvent in a weight ratio of 2:3:5 to form a mixture. The mixture was stirred with a planetary ball stirrer for 30 minutes and then applied to copper foil using a thin film coater. Two samples with different coating thicknesses (70 μm and 100 μm) were prepared and dried in a vacuum oven at 40°C for 2 hours. The dried sample was then irradiated with IPL at 2.3 kV to form a nanoporous structure.

[0203] Figures 8a and 8b show the porosity of the porous nanocomposite thin film samples. Scanning electron microscope (SEM) images show the thickness of the samples: 70 μm (a) and 100 μm (b). The SEM images of the sample surface show nanopores and micropores in the samples of two different thicknesses.

[0204] As shown in Figure 8a, the largest diameter of the voids in the 70 μm thick sample is 15 μm, and as shown in Figure 8b, the largest diameter of the voids in the 100 μm thick sample is 20 μm.

[0205] Figure 9 shows the porosity of the porous nanocomposite thin film samples obtained from gas pycnometer analysis. As shown in Figure 9, the porosity analysis using gas pycnometer revealed that the porosity of the 100 μm thick sample was 41%, which was greater than the 36% porosity of the 70 μm thick sample (see Figure 8). Although the two samples have the same composition, their thicknesses differ, resulting in different porosities. The increase in porosity with increasing thickness may be related to the drying process, which may leave some solvent in the thicker samples, increasing the porosity.

[0206] As shown in Figure 10, lithium metal negative electrode Testing was carried out using a symmetrical cell test on the nanocomposite coated sample. negative electrode and positive electrode Instead, a pair of lithium metal electrodes 1010a, 1010b are placed. A separator 1020 is placed between the pair of lithium metal electrodes 1010a, 1010b. A spacer 1030, a spring 1040, and an upper cover 1050 are sequentially placed on one of the lithium metal electrodes 1010a, and a lower cover 1060 is placed below the other lithium metal electrode 1010b. The voltage is monitored over time throughout the entire charge-discharge cycle at a constant current density. If the voltage amplitude increases and reaches a critical limit, lithium dendrites are formed and the battery is deemed to have failed.

[0207] Figures 11a and 11b show the lithium metal content of the porous nanocomposite thin film sample. negative electrode The results of the stability analysis are shown, analyzed using a symmetrical cell test on samples of various thicknesses (70 μm and 100 μm) made of PVDF, ZnO, and CNT.

[0208] As shown in Figures 11a and 11b, the voltage diagrams show that the two samples with different thicknesses (70 μm and 100 μm) have a current of 0.5 mA / cm 2 The two samples show stable cycling at high density. This clearly indicates that both samples effectively suppress the formation of lithium dendrites. Unlike the 70 μm thick sample in Figure 11a, the 100 μm thick sample in Figure 11b exhibits a larger voltage amplitude (approximately 15% increase), but its stability is similar to that of the 70 μm thick sample. The increased voltage amplitude indicates that the 100 μm thick sample has a higher porosity and volume than the 70 μm thick sample, indicating a higher energy capacity.

[0209] As an example, copper nanoparticles (Cu NPs) with an average diameter of 100 nm (Tekna) were mixed with silver nitrate (AgNO3), poly(vinylpyrrolidone) (PVP, MW: 40000 g / mol), diethylene glycol (DEG), and graphene nanoplatelets (GnP, specific surface area: 500 m 2 The ink is mixed with 1000 ppm ethanol (1000 ppm / g) and formic acid (HCOOH). To conduct the test, the ink is deposited on a 3D-printed acrylonitrile butadiene styrene (ABS) substrate using a doctor blade deposition method. The coating film is dried in a vacuum oven at 50°C for 1 hour to remove residual solvent. The conductive ink film is then sintered using an IPL process, forming a conductive network between the deposited particles. Intense light pulses from a xenon flash tube (cerium A type) are used to sinter the sample with two different angular pulses, with durations of 1 ms and 2.5 ms, respectively, and energy densities ranging from 1.07 to 3.66 J / cm. 2 is.

[0210] 12a and 12b show the comparison of the surface morphology of the copper-based metallic conductive ink before and after exposure to optical electromagnetic energy by scanning electron microscope (SEM).

[0211] As shown in Figure 12a, before IPL application, the surface of the applied copper-based metal conductive ink is composed of nothing but aggregated metal nanoparticles and crystallized metal oxides. However, as shown in Figure 12b, after IPL application, the metal oxides are reduced to metal, forming a thin sintered copper conductive network with a highly porous three-dimensional structure.

[0212] The subject matter of this disclosure may be summarized as follows.

[0213] A lithium metal battery that has the ability to suppress dendrite growth, maintain a stable SEI, and withstand internal stress caused by volumetric changes in lithium metal during repeated charge-discharge cycles. negative electrode The electrode includes: i. a copper current collector layer; ii. a lithium metal layer disposed on a surface of the current collector layer; iii. a protective layer in a three-dimensional structure having open-cell voids; and iv. a low-melting-point lithium alloy metal coating.

[0214] The lithium metal layer has an engineered surface texture that can enhance adhesion with the protective layer.

[0215] The engineered surface texture is created using a sandblasting method to project abrasive particles onto the lithium metal layer.

[0216] Abrasive particles include, but are not limited to, one or more of alumina, ground silica, and chemically inert soda lime glass beads.

[0217] The protective layer comprises a polymer nanocomposite material comprising an open-cell nanoporous polymer matrix, a carbon-based conductive nanomaterial, and a structural support material.

[0218] The present disclosure provides a method for forming a polymer nanocomposite layer having an open-cell nanopore structure, comprising the steps of: i. mixing precursor materials of a polymer nanocomposite to form a slurry; ii. applying the slurry onto a lithium metal layer using a thin-film coating method and drying; and iii. applying optical electromagnetic energy to evaporate a low-melting point polymer in the slurry and form three-dimensional open-cell nanopores.

[0219] The polymer nanocomposite slurry mixture comprises a plurality of polymers having different boiling points, a conductive carbon additive, a structural support material, and a solvent, wherein the plurality of polymers having different boiling points are selected, without limitation, from polyacrylonitrile (PAN), polytetrafluoroethylene (PTFE), poly(methyl methacrylate) (PMMA), poly(3,4-ethylenedioxythiophene)polystyrenesulfonate (PEDOT:PSS), polydiacetylene (PDA), polypropylene, polystyrene (PS), polyurethane (PU), polyethylene oxide (PEO), polyethylene terephthalate (PET), styrene-ethylene-butylene-styrene (SEBS), glycerol, sucrose, cellulose, and lignin.

[0220] The structural support additives include materials with high mechanical strength and electrochemically inert materials, such as hexagonal boron nitride (hBN), silicon nanowires (SiNW), and alumina.

[0221] The conductive carbon additive may be selected from, without limitation, single-walled carbon nanotubes (SWCNTs), multi-walled carbon nanotubes (MWCNTs), graphene, graphene oxide, graphene nanoplatelets (GNPs), and carbon dots.

[0222] The solvent includes, but is not limited to, water, N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethylsulfoxide (DMSO), or a combination thereof.

[0223] The protective layer includes a carbon nanofiber mattress having a three-dimensional open-cell porous structure.

[0224] The method for forming a carbon nanofiber mattress having an open-cell nanoporous structure includes the steps of: i. preparing a nanofiber precursor solution; ii. electrospinning a polymer nanocomposite nanofiber mattress; iii. applying optical electromagnetic energy to carbonize the polymer nanocomposite nanofibers to form carbon nanofibers; and iv. carbonizing the polymer nanocomposite nanofiber mattress with lithium metal. negative electrode and heat-compressing the same to the substrate.

[0225] The nanofiber precursor solution comprises a mixture of one or more polymers suitable for electrospinning, a conductive carbon additive, and a solvent.

[0226] The polymer may be selected, without limitation, from polyamide (PA), polyacrylamide (PAAm), polyurethane (PU), polybenzimidazole (PBI), polycarbonate (PC), polyethylene (PE), polyacrylonitrile (PAN), poly(methyl methacrylate) (PMMA), polydiacetylene (PDA), polypropylene (PP), polystyrene (PS), polyethylene oxide (PEO), polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polyvinyl chloride (PVC), polyvinylpyrrolidone (PVP), collagen, and cellulose acetate (CA).

[0227] The conductive carbon additives include, but are not limited to, one or more of single-walled carbon nanotubes (SWCNTs), multi-walled carbon nanotubes (MWCNTs), graphene, graphene oxide, graphene nanoplatelets (GNPs), and carbon dots.

[0228] The solvent includes, but is not limited to, one or more of water, acetone, formic acid, chloroform, isopropanol, N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and tetrahydrofuran (THF).

[0229] The electrospinning process uses a horizontal electrospinning apparatus with a high voltage power supply that creates a voltage difference between a syringe needle attached to a syringe pump and a drum.

[0230] In the step of attaching the carbon nanofiber mattress, thermal stress and compressive stress are simultaneously applied to attach the carbon nanofiber mattress to the lithium metal layer, and the thermal stress and compressive stress are applied indefinitely by a rolling mill, a compression molding machine, and a hot press.

[0231] The protective layer is made of a carbon nanotube network coated with metal oxide and has a three-dimensional open-cell porous structure.

[0232] A method for forming a metal oxide-coated carbon nanotube network includes: i. mixing nanocomposite precursors of a lithophilic metal oxide and a lithiphobic carbon nanotube; ii. depositing a nanocomposite of the lithophilic metal oxide and the lithiphobic carbon nanotube on a lithium metal layer using a thin film coating method; and iii. applying optical electromagnetic energy to form a carbon nanotube network with gradient lithophilic-lithiphobic properties, wherein the carbon nanotube network has a top layer of lithiphobic carbon nanotubes and a bottom layer of the lithophilic metal oxide-carbon nanotube composite.

[0233] The nanocomposite precursor mixture is used to bond carbon nanotubes to lithium metal. negative electrode The electrode comprises a lithophilic metal oxide that is attached to the electrode to maintain the network structure, and a lithiphobic carbon nanotube that forms the conductive network.

[0234] The lithophilic metal oxides may include, but are not limited to, zinc oxide, iron oxide, manganese oxide, and titanium oxide.

[0235] Carbon nanotubes may include, but are not limited to, single-walled CNTs (SWCNTs), double-walled CNTs (DWCNTs), multi-walled CNTs, functionalized CNTs, or short carbon nanofibers.

[0236] The solvent may include, but is not limited to, water, ethanol, hexane, N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethylsulfoxide (DMSO), or a combination thereof.

[0237] A current collector that inhibits dendrite growth, maintains a stable SEI, and has the ability to withstand internal stress caused by volumetric changes in lithium metal during repeated charge-discharge cycles, comprising: i. a copper metal current collector layer; and ii. a three-dimensional mesh structure coated on the copper metal current collector layer, wherein the three-dimensional mesh structure is a copper-based structure or a carbon-based structure.

[0238] A method for forming a three-dimensional copper-based network structure includes the steps of: ii. forming a slurry by mixing copper, silver, a conductive carbon additive, a polymeric carrier, and a solvent; iii. depositing the slurry onto a copper metal layer using a thin film coating method; and iii. electromagnetically sintering the deposited slurry to form the three-dimensional copper-based network structure.

[0239] The slurry includes copper-based nanoparticles, a silver salt, a polymeric carrier, a conductive carbon additive, and a solvent.

[0240] The copper-based nanoparticles may be comprised of one or more selected from, without limitation, copper, copper acetate, copper oxide, and copper formate tetrahydrate.

[0241] The silver salt may be one or more selected from, without limitation, silver, silver nitrate, silver nitrite, and silver acetate.

[0242] The polymeric carrier comprises polyethylene glycol in which polyvinylpyrrolidone has been dissolved.

[0243] The conductive carbon additive may be one or more selected from carbon black, single-walled carbon nanotubes, multi-walled carbon nanotubes, functionalized carbon nanotubes, graphene, and graphene nanoplatelets.

[0244] A method for forming a three-dimensional open-cell carbon-based network structure includes the steps of: ii. mixing a carbon precursor, a conductive carbon additive, and a solvent to form a slurry; iii. depositing the slurry on a copper metal layer using a thin film coating method; and iii. applying optical electromagnetic energy to carbonize the slurry and form a three-dimensional carbon-based network structure.

[0245] The mixture includes one or more of a carbon precursor, a conductive carbon additive, and a solvent.

[0246] The carbon precursors include industrial by-products such as asphaltenes, mesophase pitch, cellulose, cellulose nanocrystals, and lignin.

[0247] The conductive carbon additive comprises carbon black, single-walled carbon nanotubes, multi-walled carbon nanotubes, functionalized carbon nanotubes, graphene, graphene nanoplatelets, or a combination thereof.

[0248] The low melting point lithium alloy metal coating has self-repairing ability and stabilizes the solid electrolyte interfacial layer by adding lithium metal. negative electrode , protective coating or negative electrode It can be applied to the surface of a loess current collector.

[0249] lithium metal negative electrode 1. A method for forming a lithium alloy metal coating on a protective coating, comprising: i. adding a pulverized powder of lithium alloy metal to a lithium metal layer, protective coating or negative electrodeii. applying light electromagnetic energy to sinter a thin lithium alloy metal onto the surface of the lithium target.

[0250] The milled powder comprises one or more of low melting point lithium alloying metals and metalloids.

[0251] The low melting point lithium alloying metals and metalloids are selected, without limitation, from indium, tin, bismuth, gallium, silver, gold, zinc, aluminum, platinum, germanium, and field metals.

[0252] The method of depositing the material using the thin film coating method involves applying a slurry mixture of the nanocomposite material with a coater (which may be a wire coater or a doctor coater) and then placing the applied slurry in a vacuum oven to dry and evaporate all the solvent in the slurry.

[0253] A method of applying optical electromagnetic energy includes the steps of vaporizing the low boiling point material and inducing carbonization of the polymer and carbon precursor material, and sintering the conductive metal nanoparticles.

[0254] The application of optical electromagnetic energy involves applying high energy for a short period of time and absorbing the applied energy at a high rate by the carbon additive.

[0255] The application of optical electromagnetic energy involves only applying energy to the illuminated surface.

[0256] Application of optical electromagnetic energy includes irradiation with intense pulsed light (IPL), microwave, laser, plasma, or infrared oven.

[0257] A cooling device for cooling a substrate during application of optical electromagnetic energy, which reduces the temperature of the substrate in contact with a material (e.g., a lithium metal layer or a copper current collecting layer) under direct irradiation with optical electromagnetic energy, preventing damage to the substrate due to overheating.

[0258] The cooling device includes: i. a holder plate with a thermally conductive metal; and ii. a heat exchanger system such as a Peltier element or a heat exchanger system, allowing the refrigerant to be pumped to the heat exchanger after passing through the holder plate.

[0259] The holder plate is made of a specific size lithium metal negative electrode The metal plate includes a metal plate with an extruded fixing means to fit the heat exchanger system, the metal plate having a thickness sufficient to fix the heat exchanger system, and the material of the metal plate includes, but is not limited to, copper or aluminum.

Claims

1. A negative electrode of a lithium metal battery, A current collector; a lithium metal layer provided on the current collector; a protective layer having a three-dimensional open-cell porous structure provided on the lithium metal layer; a lithium alloy metal provided on the surface of the protective layer, wherein the protective layer is an open-cell nanoporous polymer nanocomposite layer comprising a polymer matrix, a conductive carbon additive, and a structural support material;

2. 10. The negative electrode of claim 1, wherein the lithium metal layer has an engineered surface texture.

3. A negative electrode of a lithium metal battery, A current collector; a lithium metal layer provided on the current collector; a protective layer having a three-dimensional open-cell porous structure provided on the lithium metal layer; a lithium alloy metal provided on the surface of the protective layer, wherein the protective layer includes a carbon nanotube network having a three-dimensional open-cell porous structure and including a lithophilic metal oxide; Here, the carbon nanotube network has a top layer made of lithiphobic carbon nanotubes and a bottom layer made of lithophilic metal oxide-carbon nanotube composite material, in a negative electrode of a lithium metal battery.

4. 4. The negative electrode of claim 3, wherein the lithophilic metal oxide comprises one or more of zinc oxide, iron oxide, manganese oxide, and titanium oxide.

5. 2. The negative electrode of claim 1, wherein the lithium alloying metal is an alloy of lithium and a low melting point metal selected from indium, tin, bismuth, gallium, silver, gold, zinc, aluminum, platinum, and germanium.

6. A method for manufacturing a negative electrode of a lithium metal battery, comprising: providing a lithium metal layer on a current collector; forming a protective layer having a three-dimensional open-cell porous structure on the lithium metal layer; forming a lithium alloy metal layer on the surface of the protective layer; wherein the steps of forming the protective layer and forming the lithium alloy metal layer comprise irradiation with optical electromagnetic energy.

7. The step of forming the protective layer includes: preparing a slurry by mixing a first polymer, a second polymer having a boiling point lower than that of the first polymer, a conductive carbon additive, a structure supporting additive, and a solvent; applying the slurry onto the lithium metal layer using a thin film coating method, and then air drying to form an intermediate coating; 10. The method of claim 6, further comprising the step of: irradiating the intermediate coating with optical electromagnetic energy to vaporize the second polymer in the intermediate coating and form nanopores.

8. the first polymer and the second polymer are selected from polyacrylonitrile (PAN), polytetrafluoroethylene (PTFE), poly(methyl methacrylate) (PMMA), poly(3,4-ethylenedioxythiophene)polystyrenesulfonate (PEDOT:PSS), polydiacetylene (PDA), polypropylene, polystyrene (PS), polyurethane (PU), polyethylene oxide (PEO), polyethylene terephthalate (PET), styrene-ethylene-butylene-styrene (SEBS), cellulose, and lignin; the conductive carbon additive is selected from single-walled carbon nanotubes (SWCNTs), multi-walled carbon nanotubes (MWCNTs), graphene, graphene oxide, graphene nanoplatelets (GNPs), and carbon dots; 8. The method of claim 7, wherein the structural support additive is selected from hexagonal boron nitride (hBN), silicon nanowires (SiNW), and alumina.

9. The step of forming the protective layer includes: preparing a nanofiber precursor solution; electrospinning the nanofiber precursor solution to produce a polymer nanocomposite nanofiber mattress; irradiating the polymer nanocomposite nanofiber mattress with optical electromagnetic energy to carbonize the polymer nanocomposite nanofiber mattress to form a carbon nanofiber mattress; and adhering the carbon nanofiber mattress to a lithium metal layer.

10. The nanofiber precursor solution includes a polymer, a conductive carbon additive, and a solvent; wherein the polymer comprises one or more of polyamide (PA), polyacrylamide (PAAm), polyurethane (PU), polybenzimidazole (PBI), polycarbonate (PC), polyethylene (PE), polyacrylonitrile (PAN), poly(methyl methacrylate) (PMMA), polydiacetylene (PDA), polypropylene (PP), polystyrene (PS), polyethylene oxide (PEO), polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polyvinyl chloride (PVC), polyvinylpyrrolidone (PVP), collagen, and cellulose acetate (CA); wherein the conductive carbon additive comprises one or more of single-walled carbon nanotubes (SWCNT), multi-walled carbon nanotubes (MWCNT), graphene, graphene oxide, graphene nanoplatelets (GNP), and carbon dots; 10. The method of claim 9, wherein the solvent comprises one or more of water, acetone, formic acid, chloroform, isopropanol, N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and tetrahydrofuran (THF).

11. The step of attaching the carbon nanofiber mattress includes: applying a thermal stress and a compressive stress simultaneously to adhere the carbon nanofiber mattress to the lithium metal layer; The method of claim 9 , wherein the thermal stress and compressive stress are applied by hot pressing.

12. The step of forming the protective layer includes: mixing a nanocomposite precursor of a lithiophilic metal oxide and a lithiphobic carbon nanotube in a solvent; applying a nanocomposite of lithiophilic metal oxide and lithiphobic carbon nanotubes onto the lithium metal layer using a thin film coating method; irradiating the carbon nanotube with light electromagnetic energy to rapidly dry the solvent and form a carbon nanotube network having a gradually increasing concentration of lithiophilic metal oxide from top to bottom; wherein the carbon nanotube network has an uppermost layer made of lithiphobic carbon nanotubes and a lowermost layer made of a lithophilic metal oxide-carbon nanotube composite material; wherein the lithophilic metal oxide includes one or more of zinc oxide, iron oxide, manganese oxide, and titanium oxide; wherein the lithium-phobic carbon nanotubes include single-walled carbon nanotubes (SWCNT), double-walled carbon nanotubes (DWCNT), multi-walled carbon nanotubes, and functionalized carbon nanotubes; 7. The method of claim 6, wherein the solvent comprises water, ethanol, hexane, N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethylsulfoxide (DMSO), or a combination thereof.

13. The step of forming a lithium alloy metal on the protective layer includes:

7. The method of claim 6, comprising the steps of depositing a powdered lithium alloy metal on a protective layer, using a rolling process to infiltrate the powdered lithium alloy metal into the protective layer having the three-dimensional open-cell porous structure, irradiating with light electromagnetic energy to melt the powdered lithium alloy metal, and then forming the molten lithium alloy metal into the three-dimensional open-cell porous structure of the protective layer based on capillary action.

14. further comprising using sandblasting to form an engineered surface texture on the lithium metal layer; The method according to claim 6, wherein the abrasive for sandblasting comprises alumina, crushed silica powder or soda lime glass beads having an average diameter in the range of 500 nm to 10 μm.

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