KR102474531B1 - Method of manufacturing anode electrode for lithium metal batteries using photoelectromagnetic energy irradiation and anode electrode for lithium metal batteries - Google Patents

Abstract

The present invention relates to a method for manufacturing a lithium metal anode, particularly an anode having a three-dimensional highly porous structure, capable of inhibiting the growth of lithium dendrites, which can reduce the electrochemical performance of a battery and cause fatal damage to a battery structure. it's about The present invention describes various types of three-dimensional structures made of different materials, such as porous polymer nanocomposites, carbon nanotube structures with lithophilic metal oxides, and electrospun carbon nanofibers created directly on a lithium metal anode. The present invention also describes a three-dimensional structure created directly on a copper current collector serving as an anode-free current collector, wherein lithium metal is applied on the three-dimensional structure consisting of a network of sintered copper nanoparticles or with a high carbon content. deposited directly on porous carbon structures produced from industrial by-products with Exemplary experiments were performed to confirm that both the carbon nanotube structure having a metal oxide coated on the lithium metal foil and the copper nanoparticle network sintered on the copper foil had a highly porous three-dimensional structure. Symmetrical cell tests performed on carbon nanotube structures with metal oxides coated on lithium metal foils showed increased stability at a constant current density of 0.5 C over repeated cycles, from which lithium dendrite growth was successful. suppressed results can be obtained.

Description

Manufacturing method of anode electrode for lithium metal battery using photoelectromagnetic energy irradiation and anode electrode for lithium metal battery

The present invention relates to an anode electrode for a lithium metal battery and a method for manufacturing the same.

In particular, the present invention substantially increases the surface area of the anode electrode by generating a three-dimensional structure on a substrate through irradiation of photoelectromagnetic energy, thereby improving lithium ion diffusion, reducing interfacial resistance, and growing lithium dendrites It relates to a method for manufacturing an anode electrode for a lithium metal battery capable of suppressing.

A method for manufacturing an anode electrode for a lithium metal battery according to an embodiment of the present invention includes generating a three-dimensional structure on a lithium metal substrate, generating a layer of a nanoporous structure of a conductive polymer nanocomposite or a three-dimensional structure of a carbon framework. create a structure A method of manufacturing an anode electrode for a lithium metal battery according to another embodiment of the present invention includes generating a porous three-dimensional structure of lithium metal composed of copper-silver-carbon nanotubes directly coated on a current collector.

Due to the increasing market demand for secondary batteries having high energy density, many studies have been conducted to develop new anodes that can replace conventional graphite-based anodes. Among various candidates for anode materials, lithium metal is considered as a promising anode material for lithium secondary batteries due to its high theoretical capacity (3860 mAh/g) and low density (0.59 g/cm ³ ). However, in spite of the above advantageous properties, several important problems prevent large-scale application of lithium metal anodes to lithium secondary batteries. One is the large volume change during the lithiation cycle and the other is lithium dendrite growth.

Lithium dendrites are metal microstructures that form on the anode during the charging process. They are formed when extra lithium ions accumulate on the anode surface due to the difference in electrodeposition rate, and grow through repeated deposition/dissolution processes. The growth of lithium dendrites can pierce the separator or cause an internal short circuit, damaging the cell and leading to catastrophic failures that cause fires or explosions.

Dendrite grows at the nucleation point of the lithium metal surface as lithium electroplating depending on battery usage. Lithium dendrites can break and lead to irreversible lithium, reducing battery capacity. In more critical cases, lithium dendrites can grow, damaging the separator and causing a short circuit between the cathode and anode, leading to a fire or explosion. Growth of lithium dendrites or volume changes of the lithium metal anode during charge and discharge cycles can cause physical damage, delamination, and breakage of the solid electrolyte interphase (SEI) layer. This leads to a continuous reaction between the lithium metal anode and the electrolyte, consuming the electrolyte while forming a new SEI layer.

Understanding the formation of lithium dendrites

In order to solve the problems associated with lithium metal batteries, many efforts have been made to understand the mechanism of lithium dendrite formation and growth. Lithium dendrites are generally understood as non-uniform deposition of lithium due to non-uniform distribution of charge. For example, a rough surface of a current collector may cause an ion flux concentrated around a tip portion of the rough surface, which causes lithium ions to be deposited more quickly around a peak, and dendrites may be formed. A dendrite growth point, such as the tip of a rough surface, is called a nucleation point.

Theoretically, there are several models suggesting the growth of lithium dendrites. The Chazlviel model [Chazlviel 1990] proposed that the presence of space charge due to the depletion of anions near the anode surface causes the formation of lithium dendrites. This model explained the dendrite growth rate in terms of ion mobility and electric field. The initiation time of dendrites followed Sand's time equation, where an increase in current density shortens the initiation time of dendrites.

Another model proposed by Monroe and Newman [Monroe and Newman 2003] suggested that the dendrite growth depends on the elasticity of the separator and is more applicable to lithium metal batteries with solid electrolytes. According to this model, it was suggested that dendrite growth can be avoided if the mechanical strength of the electrolyte is sufficiently high. However, this is not a practical solution, as electrolytes with such high modulus can reduce ionic conductivity and prevent proper cell cycling function.

Dendrite inhibition method: electrochemically stable electrolyte

Many other models have improved on this by providing the basic idea for inhibiting lithium dendrite growth. One approach is to use more electrochemically stable electrolytes, such as anion-tethered hybrid electrolytes, particularly anionic liquid-nanoparticle hybrid electrolytes. One example of such an ionic liquid is 1-methyl-3-propylimidazolium (IM) TFSI [Lu et al. 2014]. The aforementioned electrolyte is electrochemically stable, non-flammable, and has a high dielectric constant. Their electrochemical stability is due to a unique structure in which an anion is linked to a cation covalently immobilized with inorganic particles. According to Sand's time model, initiation of dendrites takes infinite time when the anion is immobilized in this case.

There are several techniques proposed to prevent or inhibit dendrite growth in lithium metal anodes, including electrolyte optimization. However, these methods have a problem in affecting the electrochemical characteristics of the battery. Another way to inhibit dendrite growth is to form an additional protective layer on the anode surface to form a stable SEI. Several studies have reported that the 3D structure can control consistent growth by evenly distributing the nucleation sites over the entire surface, thereby inducing uniform lithium deposition across the anode instead of forming dendrites. They also reported that these structures prevent lithium dendrite formation by reducing the local current density.

Three-dimensional structures can be created using a variety of materials, including three-dimensional carbon paper, carbon nanotubes, carbon fibers, conductive polymer nanocomposites, metal fibers, or lithium metal itself.

Lithium metal anode electrode, US 10483534B2

This document mainly discloses an anode electrode composed of two different layers, namely a lithium metal layer and a porous conductive layer. The porous conductive layer may include two layers, a current collector and a conductive loading layer, both of which have a plurality of pores. Also, the porous conductive layer may have a structure of a grid, mesh, rod, or combination thereof of a permeable material. The porous conductive layer provides a large surface area for lithium deposition and forms a stable SEI to reduce the formation of lithium dendrites. Also, lithium dendrites grow from or get closer to the lithium metal surface and separator due to the porous conductive layer. In addition, the electrical conductivity of the anode becomes more uniform, and lithium dendrites are reduced accordingly.

This document deals with the basic structure of a three-dimensional structure coated on a lithium metal anode to inhibit dendrite growth and prevent catastrophic failure. However, the above document does not disclose a three-dimensional conductive structure.

Lithium metal protective layer, manufacturing method thereof, and battery having the same, CN111490252A

This document discloses a porous protective layer for a lithium metal anode. The protective layer generates uniformly dispersed lithium alloy or lithium nitride, thereby improving lithium ion diffusion ability and inhibiting lithium dendrite generation. This method uses a cost-effective material that is coated on a lithium metal anode in a slurry state and then dried to form a protective layer. The material of the protective layer is composed of a metal compound, a conductive agent, and a binder, and the metal compound is a metal nitride, aluminum oxide, aluminum fluoride, or non-lithiated tetra-aluminum. Although this document describes a specific process for creating a porous structure on a lithium metal anode, it is limited to a simple slurry deposition and drying process.

Surface modification of lithium metal electrodes, DE102013114233A1

This document suggests direct modification of the surface structure of a lithium metal anode (or other metal anode) to inhibit lithium dendrite growth. Recesses of different geometries, i.e. recesses resembling blind holes and conical recesses, are created in the surface of the metal anode during processing. These recesses are formed in a rectangular, trapezoidal, dome or triangular cross section. The forming process uses a calender roll with a microneedle roller or laser to create recesses of the desired geometry. The sides of the recesses are specially grooved in the formation process when a soft metal such as lithium metal is used.

Recesses formed on the metal anode increase the surface area of the electrode. A larger surface area improves discharge rate, charge rate and cycle stability, and consequently reduces interfacial resistance. In addition, the improved cycle stability is directly related to the inhibition of dendrite growth.

Surface modification of lithium metal electrodes, KR100449765B1

The above document describes a lithium metal anode composed of an integrated separator layer, a current collector layer, and a protective film layer. The separator may be composed of porous polyethylene or polypropylene or a multilayer structure thereof. The protective film layer between the separator and the lithium metal layer has low electrolyte permeability and high lithium ion conductivity. The protective film may contain both organic and inorganic materials.

This document describes a lithium metal electrode in which a separator layer and a protective layer are integrated. However, the creation of the protective layer does not involve post-processing to improve the material properties of the raw material.

Ti ₂ Anode for lithium metal battery including C thin film, manufacturing method thereof and lithium metal battery including the same, KR 20190102489A

This document discloses forming a TiC thin film on a lithium metal anode to form a stable SEI and suppress the formation of lithium dendrites. The Ti ₂ C thin film inhibits the formation of lithium dendrites by inducing fast and stable diffusion of lithium ions. It also increases the stability of the SEI by suppressing an unwanted galvanometric reaction between the lithium metal and the electrolyte. In addition, the above document describes a method for generating a Ti ₂ C thin film on a substrate using a solution in which Ti ₂ C powder is dispersed, a Langmuir-Blodgett Scooping (LBS) method, and a transfer of the generated Ti ₂ C thin film to the surface of a lithium metal anode. start how to do it

Although the above document describes effective suppression of dendrite growth, the formation of a Ti ₂ C thin film and the transfer to the lithium metal anode require a lot of time and costly inefficient processes to etch the lithium metal anode.

Coated lithium electrode, US6955866B2

This document discloses an electrochemical cell using a lithium metal anode, wherein the anode is a ternary alloy layer composed of lithium and two other metals. In particular, the first non-lithium metal provides a matrix to accommodate the volume changes associated with lithium cycling, while the second non-lithium metal alloys with lithium and the first non-lithium metal. The first metal may be copper and the second metal may be tin. The lithium metal anode coated with the ternary alloy layer showed improved anode stability and lithium cycle efficiency.

However, this method essentially involves alloying lithium with other metals.

Interfacial process for stabilized lithium anode, US10256448B2

This document describes an electrochemical cell using a lithium metal anode that includes an interfacial layer that controls the reactivity of the lithium metal to the electrolyte and accommodates large changes in volume in the lithiation cycle. The interfacial layer allows passage of lithium ions through its walls. It also creates a stable SEI on one side of the interfacial layer, isolating lithium metal deposition and dissolution on the other side. The interfacial layer is loosely attached to the lithium metal anode, leaving a space between them to accommodate the volume change of the lithium metal anode.

The interfacial layer includes a two-dimensional atomic crystal layered material of graphene and h-BN (hexagonal boron nitride). They are chemically inert to electrolytes and lithium metal, and mechanically robust. In addition, they have small pore size, are ultra-thin and flexible. Although h-BN has all of the above properties by itself, it cannot be used directly without graphene due to its insulating properties.

This document describes a method for efficiently controlling both the mechanical and chemical aspects of lithium metal reactivity. However, forming an interfacial layer of graphene and h-BN requires a high temperature (1000 °C) and a controlled environment, and is an expensive process.

Lithium metal anode for lithium metal polymer secondary battery including spacer and method for forming the same, KR100582558B1

This document discloses a lithium metal anode divided by spacers in the form of a lattice. The spacers are laminated onto the current collector and are thicker than the lithium metal film. The openings between the spacers can be polygonal, circular or elliptical, and the spacers are mainly made of glass-reinforced fibers, carbon fibers or aluminum oxide.

The separated lithium metal films have space in the gap between the spacers to increase their volume during the lithiation cycle. Thus, a change in the volume of the lithium metal anode occurs without a change in the volume of the actual cell, maintaining the SEI and increasing the stability of the lithium metal cell.

Conventional methods have various approaches for suppressing dendrite formation in a lithium secondary battery and increasing the stability of a lithium metal anode. However, although these methods have been somewhat successful in increasing battery stability, they have the disadvantage of not being cost-effective in large-scale manufacturing processes.

US 10,483,534 B2 CN 111490252 A DE 102013114233 A1 KR 10-0449765 B1 KR 2019-0102489 A US 6,955,866 B2 US 10,256,448 B2 KR 10-0582558 B1

Y. Guo, H. Li and T. Zhai, Adv. Mater., 2017, 29, 1700007. L, Li, S. Li, and Y. Lu, Chemical Communication, 2018, 54, 6648 - 6661. C. Monroe and J. Newman, and J. Electrochem. Soc., 2003, 　150, A1377 Y. Lu, 　 K. Korf, 　 Y. Kambe, 　 Z. Tu 　and 　 L. A. Archer, 　 Angew. Chem., Int. Ed. Engl., 2014, 53, 488 - 492. N. Chazalviel, 1990, Physical Review A: Atomic, Molecular, and Optical Physics and Quantum Information, 42, 7355 - 7367. C. Monroe and J. Newman, J. Electrochem. Soc., 2005, 152, A396 - A404 C. P. Yang, Y. X. Yin, S. F. Zhang, N. W. Li and Y. G. Guo, Nat. Commun., 2015, 6, 8058 A. A. Assegie, J. H. Cheng, L. M. Kuo, W. N. Su and B. J. Hwang, Nanoscale, 2018, 10, 6125-6138. S. Choudhury, Z. Tu, S. Stalin, D. Vu, K. Fawole, D. Gunceler, R. Sundararaman, and L. A. Archer, AngewandteChemie International Edition, 2017, 56, 13070-13077. J. Xiang, Z. Cheng, Y. Zhao, B. Zhang, L. Yuan, Y. Shen, Z. Guo, Y. Zhang, J. Jiang and Y. Huang, Adv. Sci., 2019, 6, 1901120. H. Zhang, X. Liao, Y. Guan, Y. Xiang, M. Li, W. Zhang, X. Zhu, H. Ming, L. Lu, J. Qiu, Y. Huang, G. Cao, Y. Yang, L. Mai, Y. Zhao, H. Zhang, Nature Communications, 2018, DOI: 10.1038/s41467-018-06126-z. L. Liu, Y.X. Yin, J.Y. Li, N.W. Li, X.X. Zeng, H. Ye, Y.G. Guo, L.J. Wah, Joule, 2017, 1, 563-575. DOI: 10.1016/j.joule.2017.06.004. K. Chen, R. Pathank, A. Gurung, K.M. Reza, N. Ghimire, J. Pokharel, A. Baniya, W. He, J.J. Wu, Q. Qiao, Y. Zhou, 2020, Journal of Materials Chemistry A, 8, 1911 - 1919. 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. T. Wang, R. V. Salvatierra, A. S. Jalilov, J. Tian, J. M. Tour, 2017, ACS Nano, 11, 10761 - 10767. DOI: 10.1021/acsnano.7b05874.

The present invention provides an electrode manufacturing method differentiated from conventional methods. Specifically, in the present invention, it is possible to suppress lithium dendrite growth and increase the stability of a lithium metal anode by generating a nanoporous three-dimensional structure using a new opto-electromagnetic energy irradiation such as IPL (Intense Pulsed Light), and also energy-efficient It provides an electrode manufacturing method that is fast and can be applied to the current manufacturing process.

The present invention provides a method for inhibiting lithium dendrite growth and increasing the stability of a lithium metal anode in a lithium secondary battery. Specifically, the present invention provides a method of generating a three-dimensional structure in a short time by applying photoelectromagnetic energy. The purpose of the porous three-dimensional structure on the lithium metal anode is to provide the lithium metal anode with space to accommodate volume changes. The porous three-dimensional structure relates to lithium plating and is uniformly distributed to prevent growth of lithium dendrites and to maintain a stable SEI.

The present invention discloses a nanoporous conductive coating layer of nanocomposite material applied on the surface of a lithium metal anode. Nanoporous conductive nanocomposite materials can be produced by irradiating photoelectromagnetic energy such as intense pulsed light (IPL) on an applied mixture comprising a polymer matrix, a conductive additive and an evaporation additive having a low boiling point.

The present invention discloses a three-dimensional structure of carbon nanotubes applied on the surface of a lithium metal anode. A three-dimensional framework of carbon nanotubes is generated by irradiating photoelectromagnetic energy such as IPL to a mixture of randomly dispersed high aspect ratio carbon nanotubes and a metal oxide solution.

The present invention discloses a three-dimensional structure of a lithium metal anode integrated with a current collector through three-dimensional formation of copper, silver, and carbon nanotubes. The three-dimensional structure of the lithium metal anode is created by electroplating lithium onto the current collector. The surface of the current collector is pretreated with a three-dimensional structure of a copper sintered body and carbon nanotubes obtained by sintering by irradiation of photoelectromagnetic energy such as IPL.

The present invention also discloses a cooling system for transferring residual heat of lithium metal that may be accumulated during photoelectromagnetic energy irradiation.

In addition, the present invention discloses surface treatment of a lithium metal anode using sandblasting to increase the adhesion of the protective coating layer material and reduce the contact resistance.

An anode electrode for a lithium metal battery according to an embodiment of the present invention includes a current collector; a lithium metal layer disposed on the current collector; a protective coating layer having a three-dimensional structure disposed on the lithium metal layer and having open cell pores; and a lithium alloy metal coating layer disposed on the surface of the protective coating layer.

The lithium metal layer may have a processed surface texture.

The protective coating layer may be a polymer nanocomposite layer including an open cell nanoporous polymer matrix, a carbon-based conductive additive, and a structural support additive.

The protective coating layer may include a three-dimensional carbon nanofiber mattress having open cell pores.

The protective coating layer may include a network of carbon nanotubes having a three-dimensional structure of open cell pores and having a lithium-affinity metal oxide.

An upper layer of the carbon nanotube network may be a non-lithium-compatible carbon nanotube and a lower layer may be a lithium-affinity metal oxide-carbon nanotube composite.

The lithium-affinity metal oxide may include at least one of zinc oxide, iron oxide, manganese oxide, and titanium oxide.

The lithium alloying metal may be selected from indium, tin, bismuth, gallium, silver, gold, zinc, aluminum, platinum, germanium and fields metal.

An anode electrode for a lithium metal battery according to another embodiment of the present invention includes a metal current collector; and a three-dimensional network structure coated on the metal current collector, wherein the three-dimensional network structure is metal-based or carbon-based.

A lithium metal layer formed on the surface of the three-dimensional network structure may be further included.

A method for manufacturing an anode electrode for a lithium metal battery according to an embodiment of the present invention includes disposing a lithium metal layer on a current collector; forming a three-dimensional protective coating layer having open cell pores on the lithium metal layer; and forming a lithium alloy metal coating layer on the surface of the protective coating layer, wherein at least one of the protective coating layer forming step and the lithium alloy metal coating layer forming step comprises irradiating photoelectromagnetic energy. do.

The step of forming the protective coating layer includes generating a slurry in which a first polymer, a second polymer having a lower boiling point than the first polymer, a carbon-based conductive additive, a structural support additive, and a solvent are mixed, and the slurry is prepared by a thin film coating method. Forming an intermediate coating layer by coating the lithium metal layer and then drying the coating layer, and irradiating the intermediate coating layer with photoelectromagnetic energy to evaporate the second polymer in the intermediate coating layer to form nanopores.

The first polymer and the second polymer are polyacrylonitrile (PAN), polytetrafluoroethylene (PTFE), poly(methyl methacrylate) (PMMA), poly(3,4-ethylene dioxythiophene) polystyrene sulfone. nate (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, and the carbon-based conductive additive is single-walled carbon nanotubes (SWCNTs), multi-walled carbon nanotubes (MWCNTs), graphene, graphene oxide, and graphene nanoplatelets ( GNP) and carbon dots, and the structural support additive may be selected from hexagonal boron nitride (hBN), silicon nanowires (SiNW) and aluminum oxide.

The step of forming the protective coating layer includes preparing a nanofiber precursor solution, electrospinning the nanofiber precursor solution into a polymer nanocomposite nanofiber mattress, and carbonizing the polymer nanocomposite nanofibers by applying photoelectromagnetic energy. It may include forming a nanofiber mattress and attaching the carbon nanofiber mattress to the lithium metal anode.

The nanofiber precursor solution includes a polymer, a carbon-based conductive additive, and a solvent, and the polymer includes polyamide (PA), polyacrylamide (PAAm), polyurethane (PU), polybenzimidazole (PBI), poly Carbonate (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), and the carbon The system conductive additive includes at least one of single-walled carbon nanotubes (SWCNTs), multi-walled carbon nanotubes (MWCNTs), graphene, graphene oxide, graphene nanoplatelets (GNPs), and carbon dots, and the solvent is containing at least one of water, acetone, formic acid, chloroform, isopropanol, N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethyl sulfoxide (DMSO) and tetrahydrofuran (THF) can

In the step of attaching the carbon nanofiber mattress, the carbon nanofiber mattress is attached to the lithium metal layer by applying both heat and compressive stress, and the heat and compressive stress may be applied through a calendering machine, a compression molding machine, or a hot press. .

The forming of the protective coating layer may include mixing a nanocomposite precursor of a lithium-affinity metal oxide and a lithium-non-affinity carbon nanotube, and coating a lithium-affinity metal oxide and a lithium-non-affinity carbon nanotube on the lithium metal layer using a thin film coating. Depositing a nanocomposite of tubes, and applying photoelectromagnetic energy to form a network of carbon nanotubes having lithium affinity and lithium non-affinity in a gradient form, wherein the carbon nanotube network The upper layer may be a lithium-affinity carbon nanotube and the lower layer may be a lithium-affinity metal oxide-carbon nanotube composite.

Forming the lithium alloy metal coating layer may include disposing lithium alloy metal in powder form on the protective coating layer, allowing the lithium alloy metal in powder form to flow into the protective coating layer through a calendering process, and The step of melting the lithium alloy metal in powder form by irradiating magnetic energy, and the melted lithium alloy metal by capillary action may be coated on the surface of the protective coating layer.

The method may further include forming a processed surface texture on the lithium metal layer by using sandblasting.

A method for manufacturing an anode electrode for a lithium metal battery according to another embodiment of the present invention includes forming a slurry in which at least one metal nanoparticle precursor, a carbon-based conductive additive, a polymer carrier, and a solvent are mixed; depositing the slurry on a metal current collector using a thin film coating; and sintering the deposited slurry by irradiating photoelectromagnetic energy, wherein a three-dimensional metal-based network structure is formed by sintering the slurry using photoelectromagnetic energy.

The metal nanoparticle precursor includes a copper-based nanoparticle precursor, and the copper-based nanoparticle precursor may be at least one selected from among copper, copper acetate, copper oxide, and copper formate tetrahydrate.

Electroplating lithium on the metal current collector on which the three-dimensional metal-based network structure is formed may be further included.

A method for manufacturing an anode electrode for a lithium metal battery according to another embodiment of the present invention includes mixing a carbon precursor, a carbon-based conductive additive, and a solvent to produce a slurry; depositing a slurry on a metal current collector using a thin film coating; and carbonizing the deposited slurry using photoelectromagnetic energy to form a three-dimensional carbon-based network structure.

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

Electroplating lithium on the metal current collector on which the three-dimensional carbon-based network structure is formed may be further included.

With reference to the accompanying drawings, various embodiments of the present invention are described in detail by way of example and not limitation.
1 schematically illustrates surface texturing of a lithium metal layer and formation of a protective coating layer using sandblasting.
2a and 2b schematically show a method of forming a polymeric nano-porous nanocomposite coating layer on a lithium metal layer, FIG. 2a illustrates a slurry coating on a lithium foil, and FIG. 2b illustrates application of photoelectromagnetic energy This illustrates the formation of a polymer nano-porous nanocomposite coating layer on the lithium metal layer.
3a and 3b schematically show a method for generating a three-dimensional structure of carbon nanotubes on a lithium metal layer, and FIG. 3a illustrates the formation of a coating layer including carbon nanotubes and a metal oxide on a lithium metal layer, and , Figure 3b illustrates the creation of a complex three-dimensional network of carbon nanotubes and metal oxides by photoelectromagnetic energy irradiation.
Figure 4 schematically shows a cooling system for a lithium metal foil or metal current collector.
5A and 5B schematically show a method of generating a copper-silver-carbon three-dimensional structure on a current collector.
Figure 6 schematically illustrates an example of a method for coating a lithium metal layer with a lithium alloy metal to enhance the lithium-ion affinity and stabilize the SEI.
Figure 7 schematically illustrates an example of a method for coating a three-dimensional structure with a lithium alloy metal to enhance the lithium-ion affinity and stabilize the SEI.
8a and 8b show the porosity of (a) 70 μm thick and (b) 100 μm thick porous nanocomposite film samples through scanning electron microscope (SEM) images.
9 shows the porosity of porous nanocomposite film samples through gas pycnometer analysis.
10 schematically shows a symmetric cell structure for lithium metal anode stability analysis on porous nanocomposite film samples.
11A and 11B show the lithium metal anode stability analysis results for porous nanocomposite film samples of different thicknesses (70 μm and 100 μm).
12a and 12b compare surface morphologies of copper-based metal conductive inks before and after photoelectromagnetic energy irradiation.

The present invention discloses a new method focusing on photoelectromagnetic energy irradiation such as IPL (intense pulsed light) to form a three-dimensional structure to inhibit lithium dendrite growth. Materials can be deposited on a substrate and irradiated with photoelectromagnetic energy using a tape casting method or the like, and these processes are suitable for current large-scale cell manufacturing processes using a roll-to-roll process. The method proposed in the present invention is advantageous compared to other processes described below due to its short process time and high energy efficiency. The irradiated photoelectromagnetic energy is absorbed by the coated material layer to form a three-dimensional structure. In addition, photoelectromagnetic energy irradiation for a short period of time prevents transfer of residual heat from the coating layer to the lithium metal, thereby preventing direct heating of the lithium metal substrate, which may degrade performance. In addition, the present invention proposes a new cooling device for preventing thermal deterioration of lithium metal.

As the demand for lithium secondary batteries having high energy density increases, interest in new materials that can replace existing graphite anodes is also increasing. Among various candidates for new anode materials, lithium metal anode showed the highest potential due to its high theoretical capacity (3860 mAh/g), low electrochemical potential (-3.04 V), and low density (0.534 g/cm ³ ) [Guo et al . 2017].

However, the scientific community has found that the commercialization of lithium metal batteries has inherent problems that directly threaten the safety of the batteries [Whittingham 2004]. Lithium metal rapidly creates lithium dendrites during repeated cycles of charging and discharging. Lithium dendrites often break down to form irreversible lithium fragments in the electrolyte, which reduces battery capacity. In more severe cases, lithium dendrites can become sharp and penetrate the separator, causing a short circuit leading to fire and explosion.

Also, the low electrochemical potential of lithium metal is a double-edged sword, which not only provides a higher voltage for the cell, but also materials transported from all organic electrolytes and even cathode materials (e.g., polysulfides in the case of lithium-sulfur cells). ) because it reacts easily with This reaction is also irreversible and increases the rate of degradation of lithium metal cells by increasing cell impedance and reducing total capacity [Li et al. 2019]. In addition to the problems mentioned above, the large volume change of lithium metal during the lithiation cycle, consumption of the electrolyte, and unstable SEI cause degradation of the lithium metal anode.

To solve the problems associated with lithium metal anodes, the application of a protective coating layer is proposed. The present invention describes three different types of protective coatings for lithium metal anodes and one type of protective coating for current collectors. All of the protective coating layers have a three-dimensional open-cell nano-porosity structure, but they are composed of different materials. However, their manufacturing processes are similar in that they utilize processes that can be easily applied to roll-to-roll manufacturing processes, including photoelectromagnetic energy application technology. Hereinafter, examples of forming a protective coating layer of a lithium metal anode will be described in detail.

Lithium metal anode sandblasting

It is advantageous to prepare the lithium metal anode surface with an engineered surface texture prior to applying a protective coating layer to the lithium metal anode. There are several different methods for creating engineered surface textures on lithium metal surfaces, including processes such as sanding, machining, micro-needling, using femtosecond lasers, or sandblasting. The microstructures formed by these processes increase the contact surface area, thereby increasing the adhesion to the coating material, reducing the contact resistance, and increasing the ion diffusion rate (see FIG. 1).

1 schematically illustrates a sandblasting process for forming a processed surface texture 115 on a lithium metal layer 110 applied to an anode electrode of a lithium metal battery. The lithium metal layer is often referred to herein as a lithium metal anode. In addition, FIG. 1 schematically shows an example in which the protective coating layer 120 is formed on the lithium metal layer 110a having a processed surface texture.

Sandblasting utilizes a stream of abrasive particles impinging on a target surface to induce wear and surface deformation. The effectiveness of the sandblasting method is determined by the shape, size, hardness, speed and contact angle of the abrasive. 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.

Abrasive particles may include, but are not limited to, aluminum oxide, ground 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 embodiment, spherical abrasive particles were used. In this embodiment, the carrier gas applied should be an inert gas instead of the commonly used compressed air to minimize the chemical reaction between lithium metal and moisture.

In this exemplary embodiment, sandblasting is used to create a lithium metal surface having an average surface roughness (Ra) in the range of 1 to 100 μm. A variety of process parameters may be used to achieve a target average surface roughness (Ra). In one example, 80 psi of compressed argon was supplied to shoot aluminum oxide particles with an average diameter of 50 μm at a contact angle of 15°. The sandblasting area had a diameter of 2 cm, and the surface was subjected to sandblasting in two repeated cycles at a speed of 1 cm/s. The sandblasting process was performed in an argon-filled glovebox with a humidity of 0.1 ppm. Ten different points on the surface were measured using a contact profilometer (Mitutoyo SJ.201P) to find the average value of the average surface roughness (Ra) of the lithium metal anode. The measured average surface roughness (Ra) was 67.4 μm.

Sandblasting creates a rough surface, that is, a machined surface texture 115 on the lithium metal anode 110 to increase the contact area, increase the adhesion of the conductive protective coating layer 120, and reduce the interfacial resistance.

A protective coating layer having a three-dimensional open-form porous structure

For several purposes, a protective coating layer with a three-dimensional open-foam porous structure has been developed. First, the complex structure provides abundant nucleation sites where lithium can be electroplated more uniformly, instead of lithium dendrite growth concentrated in a few nucleation sites. Second, the three-dimensional structure has a much larger surface area than the planar surface, which reduces the local current density at the lithium metal anode and mitigates dendrite growth [Monroe and Newman 2005]. In addition, the submicron range structure induces a uniform charge distribution, reducing dendrite growth [Yang et al. 2015].

The low density of the three-dimensional open-form porous structure also helps relieve stress due to the volume expansion of lithium metal. Instead of increasing the volume of the lithium metal anode, lithium electroplating occurs within the three-dimensionally structured protective coating layer. If there is an internally induced or externally induced strain by the volume change, the three-dimensional structure can absorb the strain mechanically without causing additional stress.

In this embodiment, protective coating layers with three different types of three-dimensional open form porous structures are described. These are nanoporous polymer nanocomposite coatings, carbon nanotube networks with metal oxide coatings and carbon fiber mattresses.

Nanoporous polymer nanocomposite coating

Polymeric materials are very promising candidates for protective coatings of lithium metal anodes due to their material properties and ease of handling. Polymeric materials are commonly used in various parts of lithium ion batteries, from separators, binders for electrodes, and even polymer gel electrolytes in lithium solid batteries. Polymers can have various properties depending on their constituents, structures and functional groups.

The polymers used for the coating of lithium metal anodes exhibit electrochemical stability to both lithium metal and the electrolyte, homogenize the lithium ion flux near the electrode surface, prevent lithium dendrite formation, and exhibit consistent properties with the electrode under large volume changes. Reduce direct contact between lithium metal and electrolyte while maintaining contact. In addition, the polymers can be easily coated on the lithium metal anode using conventional methods such as spin coating, spray coating, film coating or doctor blading methods. If the coating method is easy, the thickness of the coating layer can be easily controlled, and is advantageous for large-scale processes.

Polymeric materials used for lithium metal anode coating include, for example, polyethylene oxide (PEO), polyether sulfone (PES), poly(dimethylsiloxane) (PDMS), poly(ethylene vinyl alcohol-β-acrylonitrile ether) ( EBC), polyvinyl alcohol (PVA), and polydopamine (PDA). The above polymers exhibit strong electrostatic interactions with lithium ions due to the polar functional groups of the polymers (eg oxygen group of PEO, cyano group of EBC, hydroxyl group of PVA).

Even without a three-dimensional structure, poly(dimethylsiloxane) (PDMS) thin films [Zhu et al. 2017] and other types of high-viscosity polymers have been used to stabilize lithium metal anodes during lithiation cycles. In addition, the polyethylene oxide (PEO) coating layer showed the formation of stable polar oligomers during the first electrochemical cycle of the lithium metal anode, resulting in a stabilized SEI layer [Assegie et al. 2018].

Another interesting example of a polymeric coating on a lithium metal anode is the use of beta (β) phase polyvinylidene fluoride (PVDF). β-phase PVDF has ferroelectricity due to its unique crystal structure and introduces a piezoelectric potential across the coating layer under stress (stress due to volume expansion of the lithium metal anode). The piezoelectric potential acts as a pump for lithium ions, accelerating lithium ion diffusion throughout the coating layer to increase the charging rate and homogenize the lithium ion flux [Xiang et al. 2019].

2a and 2b schematically show a method of forming a polymeric nano-porous nanocomposite coating layer on a lithium metal layer, FIG. 2a illustrates a slurry coating on a lithium foil, and FIG. 2b illustrates application of photoelectromagnetic energy This illustrates the formation of a polymer nano-porous nanocomposite coating layer on the lithium metal layer.

In this embodiment, the lithium metal layer 110 applied to the anode electrode of the lithium metal battery may be a lithium foil. The lithium metal layer 110 is disposed on a metal current collector such as a copper current collector. The slurry is a mixture including a high boiling point first polymer 121, a low boiling point second polymer 122 having a lower boiling point than the first polymer, and a conductive carbon additive 123, and the slurry is formed on the lithium metal layer 110 and dried in a vacuum oven to form a coating layer 120 (see FIG. 2A).

Then, application of photoelectromagnetic energy through, for example, the IPL irradiation device 201 heats the coating layer 120 to evaporate the low boiling point second polymer 121 . Through this process, nanopores 122a eventually remain in the polymer nanocomposite. Through these nanopores 122a, an open-cell porous structure in the form of continuous pores may eventually be formed (see FIG. 2B).

In this embodiment, a new manufacturing method for forming a nanocomposite coating layer having an open-cell porous structure on the lithium metal layer 110 is proposed. In this method, an open cell porous structure is created using rapid evaporation of the low boiling point material included in the protective coating layer 120 . The nanocomposite coating layer may include a main polymer matrix, a carbon-based conductive additive, a structural support additive, and a second polymer material having a significantly lower boiling point than that of the main polymer.

The primary polymer (first polymer) matrix provides the body of the porous film structure. A second polymer with a distinct low boiling point creates pores as it exits the film in a process of rapid evaporation, induced by applied photoelectromagnetic energy. Polymers usable as the first polymer and the second polymer include, for example, polyacrylonitrile (PAN), polytetrafluoroethylene (PTFE), poly(methyl methacrylate) (PMMA), poly(3,4- Ethylene dioxythiophene) 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 them, two types of polymers having a boiling point difference of, for example, 10° C. or more or 20° C. or more may be selected as the main polymer and the second polymer.

The carbon-based conductive nanomaterial forms a conductive network in a polymer matrix and serves as an absorber of photoelectromagnetic energy. Carbon-based conductive nanomaterials include, for example, single-walled carbon nanotubes (SWCNTs), multi-walled carbon nanotubes (MWCNTs), graphene, graphene oxide, graphene nanoplatelets (GNPs), or carbon dots. include

Structural support additives are materials that have high mechanical strength and are electrochemically inert. These improve the mechanical strength and durability of porous polymer nanocomposites. Some examples of structural support additives include hexagonal boron nitride (hBN), silicon nanowires (SiNW) and aluminum oxide.

The above components are mixed with a solvent suitable for the polymer used in the mixture to form a slurry, and then coated on the surface of the lithium metal anode using a thin film coating technique such as doctor blading, bar coating, spray coating or solution casting. and a film is formed. The membrane is completely dried in a vacuum oven. For rapid evaporation of the second low-boiling polymer, the dried film is irradiated with photoelectromagnetic energy to create an open-cell porous structure when the evaporated gas escapes the film.

CNT network with metal oxide

Carbon-based conductive materials are used in a variety of applications due to their high electrical conductivity and mechanical strength. Among various carbon-based conductive materials, carbon nanotubes (CNTs) are known to have a high aspect ratio, especially as they have nanometer-scale diameters and micrometer-scale lengths. The high aspect ratio, high electrical conductivity, non-lithium affinity material property, and three-dimensional structure of CNT can form an ideal interfacial layer on the lithium metal anode to prevent lithium dendrite formation and promote lithium ion diffusion while forming a stable SEI layer. have.

However, the non-lithium affinity nature of CNTs poses problems for attaching CNT-based structures to lithium metal anodes. Zhang et al. [Zhang et al. 2018] reported a lithium metal anode with an interfacial layer containing gradient lithophilic-lithophilic properties. CNTs containing various zinc oxide (ZnO) were dropped on a lithium foil layer by layer to form a lower layer with lithium affinity and an upper layer with non-lithium affinity. A lithium metal foil with a gradient lithium affinity-lithium affinity layer and a lithium metal foil coated only with CNTs were compared. In a symmetrical cell test performed at a constant current density of 1 mA cm ⁻² , the gradient type lithium affinity-lithium affinity layer formed on the lithium metal foil was relatively weak compared to the lithium metal foil coated only with CNT. It showed excellent cycle stability. In the symmetrical cell test, sample lithium foils are placed in a coin cell as both anode and cathode, and then subjected to charge and discharge cycles under constant current density. The amplitudes of the charge and discharge voltages must be kept constant. When an increase in voltage amplitude is observed, the formation of lithium dendrites within the cell is considered to have started. The sample with the gradient lithium affinity-lithium affinity layer showed stability for up to 500 hours of cycling, while the sample coated only with CNT showed unstable behavior with increasing voltage amplitude after 200 hours of cycling.

The idea of a gradient lithophilic-lithium-phobic interfacial layer is one of the promising methods to inhibit lithium dendrite growth in lithium metal batteries. However, the method proposed by Zhang et al. has a complicated fabrication process. For example, to create a gradient layer, solutions having different concentrations of CNTs and zinc oxide must be prepared. Layer by layer is deposited on the lithium foil, which requires a drying process between deposition of each layer, thereby increasing manufacturing time. Due to the low melting point of lithium metal (180 °C), the solvent cannot be quickly dried at high temperatures.

3 schematically shows a method for generating a three-dimensional structure of carbon nanotubes on a lithium metal layer.

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

Photoelectromagnetic energy irradiation through IPL heats the coating layer 320, evaporates the solvent 321, and creates a complex three-dimensional network of carbon nanotubes 325a and metal oxide 322 connected to each other (see FIG. 3B). .

In the present invention, a new method of using photoelectromagnetic energy is proposed. The gradient of lithophilic and lithophilic layers is not created by depositing them layer by layer, but through the effect of photoelectromagnetic energy. Instead of several solutions with different concentrations of CNTs and zinc oxide, one slurry mixture of CNTs, metal oxides, a small amount of polymeric binder and solvent is deposited on a lithium metal foil and irradiated with photoelectromagnetic energy. The photoelectromagnetic energy vaporizes the coated polymer and reduces the metal oxides in the top layer, leaving a lithium-incompatible CNT layer on top. Since the irradiated photoelectromagnetic energy is applied from the top, the energy transferred to the depth of the coated slurry is small, and the lithium-affinity metal oxide and polymer binder remain in the bottom layer.

The lithophilic metal oxide may include, but is not limited to, one or more of zinc oxide, iron oxide, manganese oxide, and titanium oxide. 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), dimethyl formamide (DMF), dimethyl sulfoxide (DMSO), or combinations thereof.

Figure 4 schematically shows a cooling system for a lithium metal foil or metal current collector.

The cooling system as illustrated in FIG. 4 is for transferring residual heat of the metal current collector or the lithium metal layer 110 that may be accumulated during the photoelectromagnetic energy irradiation process in FIGS. 2B and 3B .

The cooling system includes a holder plate 401 having a thermally conductive metal, a refrigerant inlet 410 disposed on one side of the holder plate, a heat exchange passage 420 extending from the refrigerant inlet into the holder plate, and one side or the other side of the holder plate. and a refrigerant outlet 430 connected to the heat exchange passage 420.

The holder plate 401 can include a metal plate with an extruded fixture to fit a lithium metal anode of a specified size, the metal plate being thick enough to hold the heat exchanger system, and the material of the metal plate including, but not limited to, , copper or aluminum.

The refrigerant inlet 410 and the outlet 430 may be connected to a refrigerant pump or the like. Alternatively, a Peltier element may be disposed instead of the heat exchange passage through which the refrigerant flows.

A refrigerant such as cooling water passes through the heat exchange passage 420 made of a material having high thermal conductivity. For example, aluminum in contact with a lithium metal anode removes additional heat absorbed by the lithium metal anode through photoelectromagnetic energy irradiation.

Carbon nanofiber/fibre mattress

A matrix of carbon fibers is another porous carbon structure that can be applied to lithium metal anodes to inhibit lithium dendrite formation and provide space for lithium deposition during charging. The manufacture of carbon fibers is a relatively well-established process. In many cases, a long process time and high heat are required to stabilize and carbonize the carbon precursor material, but a carbon fiber matrix can be separately manufactured and attached to the lithium metal anode after all processes involving high temperatures. The temperature and pressure required to bond the carbon fiber mattress to lithium metal is generally kept below the melting point of lithium metal (180.5 °C).

In 2017, Liu et al. created a free-standing hollow carbon fiber structure on a lithium metal anode by carbonizing commercial cotton. They observed that lithium deposition occurred on the inner surface of the carbon fibers as well as the outer surface of the carbon fibers, filling the gaps between the various carbon fibers and also filling the empty spaces inside the carbon fibers. A lithium metal anode coated with a hollow carbon fiber structure that maximizes the increased surface area and porous structure showed stability even after 600 cycles under the symmetrical cell test, when bare lithium foil became unstable after 180 cycles under the same conditions [Liu et al. 2017]. Another study conducted by Zhang et al. coated the carbon fibers with a layer of lithophilic silver by directly electroplating silver on the carbon fibers. This made the implantation of lithium easier and resulted in a similarly stable lithium metal anode compared to pure lithium metal [Zhang et al. 2017].

In the present invention, a new method for generating a three-dimensional carbon fiber structure on a lithium metal anode is proposed to inhibit dendrite growth and maintain stability. The method uses photoelectromagnetic energy irradiation for the carbonization process, increasing energy efficiency and reducing processing time. To compensate for the low energy penetration depth, an electrospinning process can be used to create polymeric nanocomposite nanofibers containing carbonaceous nanoparticles. Carbonaceous nanoparticles with smaller diameter nanofibers and high energy absorbance reduce the energy threshold required for carbonization.

A horizontal electrospinning device may be used to spin the polymer nanocomposite nanofibers. The electrospinning device uses a high voltage power supply, which is connected to the needle of a syringe mounted on a syringe pump. The chassis of the pump and the rotating drum are grounded. The drum rotates at a constant speed and the chassis is connected to a high resistance (approximately 100 MΩ) resistor to maximize deposition on the drum and minimize fiber deposition elsewhere. The flow rate into the system is set to maintain a single droplet at the tip of the needle. A syringe pump is mounted on an XY stage programmed for oscillatory motion, depositing fibers uniformly over the entire drum. Electrospinning is a cost-effective and easy alternative that can be used to produce nanoscale fibers and nonwoven mats. Electrospinning makes it possible to control the surface area and porosity of the resulting fiber mattress.

From the electrospinning process, a mixture of polymer, carbonaceous nanocomposite and solvent is spun. Applicable polymers include 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), poly It includes at least one of vinyl chloride (PVC), polyvinyl pyrrolidone (PVP), collagen and cellulose acetate (CA).

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.

The solvent may vary depending on the polymer used, but is not limited to water, acetone, formic acid, chloroform, isopropanol, N-methyl-2-pyrrolidone (NMP), dimethyl formamide (DMF), dimethyl sulfoxide (DMSO ) and tetrahydrofuran (THF), or a combination of two or more thereof.

Electrospun polymer nanocomposite nanofibers can be carbonized using photoelectromagnetic energy. In this process, the spun fibers may be irradiated with photoelectromagnetic energy while placed on a substrate different from the lithium metal anode, and high-intensity IPL may be applied to completely carbonize the carbon fiber mattress from both sides. After the polymer nanocomposite nanofibers have been carbonized into a carbon fiber matrix, they can be transferred to a lithium metal anode using a hot press technique in which heat and pressure are applied.

Application of opto-electromagnetic energy through Intense Pulsed Light (IPL)

The most important step in generating an open-cell porous three-dimensional structure on a lithium metal anode or a film coated on a current collector is an energy application step. In conventional methods, application of thermal energy through pyrolysis is the most common, but this generally consumes a lot of energy and time. In addition, since a process of applying energy to a film coated on a lithium metal anode is required, thermal decomposition involving high temperatures (400-800 °C) cannot be used due to the low melting point (180.5 °C) of lithium metal. In the present invention, it is used to apply energy without damaging the lithium metal anode using a photoelectromagnetic energy application method, that is, IPL (Intensive Pulsed Light) or the like.

Intense Pulsed Light (IPL) uses rapid optoelectronic waves generated from a xenon lamp. Application of high-intensity pulses of electricity through the xenon gas-filled lamp results in photon irradiation as the xenon gas is excited to a higher energy state and then falls back to a lower energy state. IPL technology has advantages over other electromagnetic energy application processes such as laser and microwave because it can cover a large surface area in a short time (several milliseconds).

In addition, IPL has a broad spectrum of pulsed light, generally ranging from 200 nm to 1100 nm, whereas laser or microwave technology has a more limited wavelength spectrum. Modern IPL devices use computer-controlled capacitor banks to generate IPLs with controlled pulse duration, pulse interval, pulse number, and intensity. Fluence (radiant energy received by a surface per unit area) is related to the distance from the source of energy to the target surface, the angle of the reflector, and the absorbance of the target surface.

As mentioned above, the mixture encapsulating the active material has a carbon additive with high absorbance in a broad spectrum and converts the absorbed energy into thermal energy to form a nanoporous structure. This means that the energy efficiency of the IPL process is much higher and much faster than the pyrolysis process. This method is applicable to large-scale cell manufacturing processes including conventional roll-to-roll manufacturing processes due to high energy efficiency and short process time.

Considering a typical IPL system, the diffusion depth of IPL irradiation is limited to about 1 μm at the surface. When bulk materials are being processed, this limited diffusion depth may be undesirable. However, in this embodiment, sufficient energy is delivered to the thin film coating layer to produce the desired effect in the coating layer. At the same time, energy is not transferred or has minimal effect on the subsurface layer, preventing damage to the lithium metal anode under the coating layer. This can also lead to interesting effects, such as creating a gradient effect, as described for creating a gradient lithium affinity-lithium affinity layer of carbon nanotubes and metal oxides.

Anode-less copper current collector with three-dimensional structure

A protective coating layer with a three-dimensional open-form porous structure on the lithium metal anode was developed to prevent dendrite growth and excessive internal stress due to volume change associated with the lithiation cycle. However, since the lithiation process of a lithium metal anode is an electrodeposition of lithium ions, a question has been raised as to whether a lithium metal layer is necessary. The source of lithium ions was the cathode, and the anode was only needed to store lithium ions in the form of electrodeposited lithium. This led to the conclusion that an 'anode-less' current collector could function as an anode for a lithium metal battery.

A support or structure capable of storing lithium ions during the lithiation process is required to properly function the 'anode-free' current collector. Therefore, a three-dimensional open-form porous structure was again required for the current collector. The three-dimensional open form porous structure on the current collector provides the same benefits that the protective coating layer provides to the lithium metal anode. This provides abundant nucleation sites and space for lithium deposition during the lithiation cycle, and prevents volume change, thereby preventing excessive internal stress. Additionally, the high surface area of the highly conductive material promotes uniform charge distribution, mitigating dendrite formation. When there is internal or external mechanical stress, the three-dimensional structure of the current collector may serve as a structural support for absorbing the stress.

Various studies have been conducted to fabricate a three-dimensional structure or support for an anode-free current collector. The creation of surfaces with high surface roughness, chemical and mechanical etching of current collector surfaces, construction of additional structures outside polymers, metals or carbonaceous materials have been proposed.

For example, copper-carbon framed three-dimensional structures have been built on copper current collectors [Chen et al. 2020]. The three-dimensional structure was fabricated by first forming a carbon framework through thermal decomposition of melamine-formaldehyde foam and then electroplating copper thereon. As a result of the battery test, 99.85% of the capacity was maintained even after more than 300 cycles, so excellent electrical conductivity, increased surface area, stable SEI and dendrites could be mitigated. However, in the case of the above method, it is necessary to maintain a high temperature of 900 ° C. for 2 hours in an N ₂ atmosphere to prepare a carbon framework, and an electric current for 10 minutes using copper and toxic CuSO ₄ (copper sulfate) electrolyte. It should be plated.

In another example, a copper foam was prepared as a current collector, to which reduced graphene oxide (rGO) was adhered [Yu et al. 2019]. In this method, the fabrication method involved immersing the copper foam in a liquid containing a graphene oxide suspension for 12 hours to obtain reduced graphene oxide (rGO) covering the copper foam. In half-cell tests using rGO covered copper foam as anodes for lithium metal cells, it was found that the Coulombic efficiency (CE) remained above 98.5% after 350 cycles. However, although the process was simple, this process also required a long processing time (12 hours) and expensive low-density copper foam.

Metal-based 3D structure for current collector

In the present invention, a three-dimensional structure of a metal-based network is proposed, which is obtained through an opto-electromagnetic energy sintering process after film coating of a metallic conductive ink. The three-dimensional structures are mainly composed of conductive metals and small amounts of additives.

5 schematically illustrates a process of manufacturing a conductive metal three-dimensional structure on a current collector, taking copper-based conductive ink as an example. More specifically, FIG. 5 shows a method of generating a copper-silver-carbon three-dimensional structure on a copper current collector 510 . After that, a lithium metal anode may be formed by performing lithium electroplating in the charging process.

In this embodiment, the current collector is made of copper. A conductive ink mixture is applied to the surface of the current collector and dried in a vacuum oven (see FIG. 5A). In this embodiment, the conductive ink mixture is composed of a solvent carrier, copper nanoparticles 511, silver nanoparticles 512, and conductive carbon additive 513, but is not limited thereto, and a wide range of materials may be used depending on specific applications. Other ratios may be used.

After that, for example, using the IPL irradiation device 501, the copper nanoparticles are sintered by irradiation of photoelectromagnetic energy to form copper 511, silver 512a, and conductive carbon additive 513 on the surface of the current collector 510. form a three-dimensional conductive network of

The three-dimensional conductive network formed on such a current collector may itself become an anode electrode. During the charging process, lithium is electroplated on the current collector on which the 3D conductive network is formed, and as a result, a lithium metal anode electrode can be formed in the 3D structure (see FIG. 5B ).

Conductive metal nanoparticles will primarily be copper-based nanoparticles. Copper-based nanoparticles may include, but are not limited to, pure copper nanoparticles, copper formate, copper oxide, copper nitrate, copper nitrite, copper acetate nanoparticles, and coated nanoparticles with a protective layer of tin or polymer. They may not be conductive by themselves, but upon exposure to a critical amount of energy, the metal nanoparticles melt instantaneously to form a conductive bridge.

The polymeric carrier may include, but is not limited to, diethylene glycol (DEG) and/or poly(N-vinylpyrrolidone) (PVP), both of which are commonly used conductive ink carriers. Additives can be metals and non-metals, and each additive has a specific purpose for which it is added. The protective layer and additives surround the main metal conductor (ie copper nanoparticles) and fill the gaps between the nanoparticles. They also function to improve conductivity, scavenge and inhibit oxidation, reduce energy required for sintering, absorb energy, improve solderability and adhesive properties, protect against corrosion and wear, and improve self-healing capabilities. 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 Fin nanoplatelets and carbon nanotubes may be included, and they may have various sizes.

The mixture is prepared by stirring and sonication. Since solvents and carrier polymers may not dissolve some of the key materials, sonication at ultrasonic frequencies is required to improve the dispersibility of the materials. A mixture of conductive ink is applied onto the current collector through bar coating, spray coating, doctor blading, and various other film coating methods. The applied ink mixture is subjected to a low temperature (< 50 °C) vacuum drying process to evaporate residual solvent.

As the deposited conductive ink particles form a loose layer with gaps between the conductive metal particles, they are not immediately conductive in the dry state. Applying energy, usually in the form of heat, partially melts the nanoparticles, forming a conductive bridge between them. There is an existing pioneering technology for sintering of nanoparticles.

Existing methods of sintering metal nanoparticles require temperatures in the range of 150 to 300 °C in an inert gas environment. In addition, preparing these temperature and gas environments takes time and requires expensive equipment along with heat-resistant substrates. These conditions may make existing sintering methods unsuitable for practical applications.

In the present invention, application of photoelectromagnetic energy is used to sinter the metal particles. The method of applying photoelectromagnetic energy may include irradiating at least one of intense pulsed light (IPL), laser, infrared (IR), and microwave. Optoelectromagnetic energy application methods have several advantages over conventional pyrolysis or heat application. First of all, photoelectromagnetic energy application is more energy efficient. Unlike other heating methods in which the temperature of the entire volume of the heating chamber must be increased, photo-electromagnetic energy application directly applies energy to the target surface. In addition, the energy absorption efficiency is further increased by adding the carbon additive, thus requiring less power consumption.

In addition, the photoelectromagnetic energy application method irradiates energy only for a short period of time. The IPL method uses a flash of xenon light for only a few milliseconds to cover a large surface area. Laser or microwave methods can take several seconds per area irradiated, which can still result in high feed throughput in roll-to-roll manufacturing processes. Although the power required for the process can be high, the total amount of energy required for the process is much less than conventional heat application processes due to the fast turnaround time. Most importantly, since the photoelectromagnetic energy application method does not require a chamber or an inert environment, the photoelectromagnetic energy application method can be applied without significant modification to current anode manufacturing facilities.

Carbon-based three-dimensional structure for copper current collector formed from industrial by-products

Carbon has been recognized as an advantageous material for a three-dimensional structure attached to an anode-free current collector due to its high electrical conductivity, structural rigidity, and easy formation of a three-dimensional structure.

A variety of carbon sources were considered as potential candidates. For example, Aruna Zhamu and Bor Z. Jang of the Global Graphene Group described an anode electrode consisting of a lithium metal layer and a porous conductive layer made of graphene. The porous conductive layer reduces lithium dendrite formation by increasing the surface area for lithium deposition and forming a stable SEI. The electrical conductivity of the anode becomes more uniform, and lithium dendrites are reduced. However, this technology only covers the basic structure of the three-dimensional structure coated on the lithium metal anode to prevent dendrite growth and fatal damage, and does not include an efficient manufacturing process for forming the three-dimensional structure.

As another example, Zhaohui Liao, Chariclea Scordilis-Kelley, and Yuriy Mikhaylik in 2012 created a uniformly dispersed lithium alloy and/or lithium nitride over a lithium metal anode to demonstrate a porous protective layer. This increases the lithium-ion diffusion capacity and prevents lithium dendrite formation. This method uses cost-effective materials to coat a lithium metal anode with a slurry, which is then dried to form a protective layer. The protective layer material is composed of a metal compound, a conductive agent and a binder, and the metal compound is one of metal nitride, aluminum oxide or aluminum fluoride. However, this method describes a process for creating a porous structure, but this process is limited to a simple slurry deposition and drying process. In addition, the drying process takes 720 hours, which is time inefficient.

Another potential carbon precursor for porous carbon structures is industrial by-products such as asphaltenes, pitch, cellulose, lignin, and the like. Asphaltenes are industrial by-products found in crude oil. Asphaltenes are usually eliminated because their high viscosity and high carbon content negatively affect production and energy efficiency as a fuel. As such, since asphaltenes have been regarded as a waste product in the oil and gas industry, asphaltenes are inexpensive and have abundant supplies. The use of asphaltenes in the production of advanced lithium-ion batteries is advantageous both economically and environmentally. Pitch is another high-carbon industrial by-product derived from petroleum, coal tar or wood. Cellulose and lignin are high-carbon substances found in plant materials such as rice husk, wheat straw and sawdust, which are by-products of the agro-forestry industry.

Others have discovered the advantages of asphaltenes as a carbon source for forming three-dimensional structures in current collectors. Wang et al. fabricated an ultra-fast charge high capacity lithium metal battery using asphaltenes [Wang et al. 2017]. In this study, they used untreated gilsonite as a carbon precursor. Gilsonite is a naturally occurring black, hard, lightweight material with a high asphaltene content. The untreated gilsonite was pre-treated at 400 °C for 3 hours in an argon-filled environment and then pulverized in a mortar with potassium hydroxide (KOH). The mixture was heated at 850 °C for 1 hour, then filtered, washed with water and dried at 110 °C for 12 hours. A mixture of KOH and pretreated gilsonite, graphene nanoribbon (GNR) and polyvinylidene difluoride (PVDF) were mixed in a mortar at a mass ratio of 4.5:4.5:1, and N-methyl-2-pyrrolidone (NMP ) solvent was added to form a slurry. This slurry was coated on a copper foil and then dried overnight in vacuum at 50° C., resulting in a porous carbon structure referred to as an Asp-GNR-Li anode.

They found that the Asp-GNR-Li anode exhibited higher capacitance compared to conventional copper-lithium anodes over a full range of current densities. In addition, in repeated charge-discharge cycles at a constant current density of 0.5 C, the Asp-GNR-Li anode was found to retain 90% of its specific capacity even after 130 cycles, whereas the conventional copper-lithium anode maintained 75% of its specific capacity after 130 cycles. fell below %. This trend showed that the specific capacity of the conventional copper-lithium anode rapidly decreased with increasing cycle number.

The idea of using high carbon content asphaltenes as precursors to carbon structures holds great potential, especially due to their cost effectiveness and abundant supply. However, the fabrication process proposed in Wang et al.'s study included many steps requiring high temperatures and long processing times.

On the other hand, in the present invention, a new manufacturing method for generating an anode-free current collector having a porous carbon structure on a copper foil by utilizing photoelectromagnetic energy irradiation is proposed. As mentioned above, the opto-electromagnetic energy application method has advantages over conventional furnace heating processes due to being an energy efficient and time efficient process. Since the method of applying photoelectromagnetic energy does not require a furnace, chamber, or inert environment, it can be readily applied to large-scale manufacturing processes including roll-to-roll processes.

In this method, a slurry mixture of carbon precursor, conductive carbon additive and solvent is prepared. Carbon precursors include industrial byproducts with a high carbon content such as asphaltenes, meso-phase pitch, cellulose, cellulose nanocrystals and lignin. Conductive carbon additives add structural rigidity, increase electrical conductivity and increase energy absorbance for opto-electromagnetic energy. The conductive carbon additive includes any one or a combination of two or more of carbon black, single-walled carbon nanotubes, multi-walled carbon nanotubes, functionalized carbon nanotubes, graphene, and graphene nanoplatelets. The slurry mixture is deposited on the copper foil using a thin film coating method. When the slurry is dried on the copper foil, photoelectromagnetic energy is applied to carbonize the slurry to form a three-dimensional carbon-based network structure. Thereafter, lithium may be electroplated on the surface of the three-dimensional carbon-based network structure during the charging process.

Low melting point lithium alloy metal coating

An additional coating of a lithium alloy metal with a low melting point can help stabilize the SEI layer. This metal coating can be applied on the lithium metal layer or protective coating layer or on the anode current collector. They exploit three different properties: high electrical conductivity, fast alloying reaction with lithium ions and self-healing to stabilize the SEI layer.

Lithium alloy metals generally have higher electrical conductivities than copper and silver. Coating on the lithium metal layer reduces the contact resistance between the electrolyte and the anode, increasing the charge transfer rate. Studies have shown that the application of an indium coating on a lithium metal anode greatly reduces the electrical contact resistance between the electrolyte and the anode [Choudhury et al. 2017].

Studies have shown that indium makes it possible to rapidly diffuse lithium ions through surface diffusion. Density-function theory calculations were performed and it was found that indium has a small diffusion barrier on its surface. Lithium ions are loosely bound to the indium coating layer and move rapidly over the indium coating layer to be electrodeposited onto the underlying lithium metal layer [Choudhury et al. 2017]. The faster ionic conductivity also mitigates the formation of dendrites.

Finally, metals such as indium have a self-healing ability to maintain the SEI during cycles of volume change due to lithiation and delithiation. A small amount of metal salt can be added to the electrolyte to electroplate metal in a liquid electrolyte environment, so that the metal coating layer damaged in the process can be restored. This is possible because indium is relatively inert to commonly used electrolytes, suppressing side reactions. A study on indium coating of lithium metal anodes showed that the energy capacity retained more than 90% of the original energy capacity after 250 charge and discharge cycles [Choudhury et al. 2017].

In a solid electrolyte environment, lithium alloy metal coatings can take advantage of their low melting point for self-healing. Field's metal is an alloy of bismuth, indium, and tin, and these metals have relatively high melting points of 271.4 °C, 156.6 °C, and 231.9 °C, respectively, but the melting point of the field metal alloyed with them is only 62 °C. The low melting point allows the metal coating to self-heal by passively using heat generated by the battery's internal resistance or by actively using the battery's Joule heating system, which is commonly used for battery temperature management in cold environments. The self-healing ability keeps the SEI layer stable, mitigates dendrites, and maintains the electrolyte and active material through repeated charge and discharge cycles.

Figure 6 schematically illustrates an example of a method for coating a lithium metal layer with a lithium alloy metal to enhance the lithium-ion affinity and stabilize the SEI. Referring to FIG. 6 , the pulverized lithium alloy metal powder 620 is directly disposed on the lithium metal layer 610 . Thereafter, sintering of the lithium alloy metal powder using photoelectromagnetic energy is applied. The instantaneous sintering process allows the partially melted lithium alloy metal to be evenly coated on the surface of the lithium metal anode 610 to form the lithium alloy metal coating layer 620a.

Figure 7 schematically illustrates an example of a method for coating a three-dimensional structure with a lithium alloy metal to enhance the lithium-ion affinity and stabilize the SEI. Referring to FIG. 7 , pulverized lithium alloy metal powder 620 is disposed on a three-dimensional structure 710 coated on a lithium metal layer 610 . The lithium alloy metal powder 620 is then calendered into the three-dimensional structure 710 coated on the lithium metal anode. Thereafter, sintering of the lithium alloy metal powder using photoelectromagnetic energy is applied. The instantaneous sintering process allows the partially melted lithium alloy metal to be evenly coated on the surface of the 3D structure 710 to form the lithium alloy metal coating layer 620a.

The coating of the lithium alloy metal having a low melting point may be applied directly to the lithium metal layer as in the example shown in FIG. 6 or applied on a three-dimensional open cell porous protective coating layer on the lithium metal layer as in the example shown in FIG. 7 .

Hereinafter, referring to FIG. 7, an embodiment of coating a lithium metal layer or a three-dimensional protective coating layer by melting lithium alloy metal powder in a short time while minimizing thermal influence on the lower lithium metal layer using photoelectromagnetic energy irradiation will be described. do. This method is different from coating metal using conventional hot melt dip coating or electrodeposition methods.

In this embodiment, a method by which a low melting point lithium alloy metal coating layer can be formed by a simple method using calendering, application of photoelectromagnetic energy and capillary action is described. First, a low melting point lithium alloy metal is prepared in powder form. Metals and metalloids that can be used as low-melting lithium alloy metals include, but are not limited to, eutectic alloys such as indium, tin, bismuth, gallium, silver, gold, zinc, aluminum, platinum, germanium, and fields metals. ) may be included. Due to their malleable nature, these metals and metalloids need to be freeze milled to make fine powders.

The metal powder may be randomly deposited on the surface of the 3D protective coating layer, and may pass through the voids of the 3D protective coating layer through a calendering process by applying pressure and heat. When photoelectromagnetic energy is applied, the metal powder is melted and wetted into a three-dimensional structure by capillary action. This process is possible due to the low melting point of this metal because the required temperature does not damage the substrate (ie the lithium metal layer with the protective coating layer).

To confirm the effect on the inhibition of lithium dendrite formation, a sample of the three-dimensional structure of the CNT network with 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 mixed for 30 minutes using a planetary ball mixer, and then coated on copper foil by a thin film coating method. Two samples having a coating layer thickness of 70 μm and 100 μm were prepared and dried in a vacuum oven at 40° C. for 2 hours. Thereafter, the dried samples were irradiated with IPL at 2.3 kV power to create a nanoporous structure.

8a and 8b show the porosity of (a) 70 μm thick and (b) 100 μm thick porous nanocomposite film samples through scanning electron microscope (SEM) images. Scanning electron microscopy (SEM) images of the sample surface show both nano- and micro-pores of the samples with two different thicknesses.

Also, referring to FIG. 8A , the sample having a thickness of 70 μm had a maximum pore diameter of 15 μm, and referring to FIG. 8B , the sample having a thickness of 100 μm had a larger maximum pore diameter of 20 μm.

9 shows the porosity of porous nanocomposite film samples through gas pycnometer analysis. Referring to FIG. 9 , it can be seen from the porosity analysis using a gas pycnometer that the porosity of the 100 μm thick sample is 41%, which is greater than the porosity of 36% of the 70 μm thick sample. The two samples have the same composition, but different porosity due to the difference in thickness. Increased porosity with increasing thickness may be related to the drying process, and relatively thick samples may have some residual solvent, resulting in increased porosity.

A sample of the nanocomposite coating on a lithium metal anode was tested using a symmetrical cell as shown in FIG. 10 . In the symmetrical cell test, a pair of lithium metal electrodes 1010a and 1010b are placed instead of the anode and cathode. A separator 1020 is disposed between the pair of lithium metal electrodes 1010a and 1010b. A spacer 1030, a spring 1040, and an upper cap 1050 are sequentially disposed on one side of the lithium metal electrode 1010a. A lower cap 1060 is disposed under the other lithium metal electrode 1010b. Under constant current density, voltage over time is monitored over charge and discharge cycles. When the amplitude of the voltage increases and reaches a critical limit, lithium dendrites form and the cell is considered to have failed.

11a and 11b show results of lithium metal anode stability analysis on porous nanocomposite film samples. Samples of different thicknesses (70 μm and 100 μm) composed of PVDF, ZnO and CNT were analyzed using the symmetrical cell test.

Referring to FIGS. 11A and 11B , for two samples having a thickness of 70 μm and 100 μm, the voltage graphs showed a stable cycle at a constant current density (0.5 mA/cm ² ), and lithium dendrites were successfully formed in both samples. shows that it is suppressed by Referring to the results for the 100 μm thick sample in FIG. 11 b, when compared to the results for the 70 μm thick sample in FIG. showed stability. The increased voltage amplitude suggests an increased energy capacity due to the higher porosity and volume compared to the 70 μm thick sample.

Illustratively, copper nanoparticles (Cu NPs) (Tekna) with an average diameter of 100 nm are silver nitrate (AgNO ₃ ), poly(N-vinylpyrrolidone) (PVP, MW: 40,000 g/mol), diethylene glycol ( DEG), graphene nanoplatelets (GnPs, specific surface area: 500 m ² /g) and formic acid (HCOOH). For testing purposes, a doctor blade method was applied to deposit ink on a substrate made of 3D printed acrylonitrile butadiene styrene (ABS). The coated membrane was dried in a vacuum oven at 50 °C for 1 hour to remove residual solvent. Then, the conductive ink film was sintered using an IPL treatment to form a conductive network between the deposited particles. The samples were sintered by IPL irradiation of a xenon flash tube (Cerium Type A) with two different square pulses of 1 ms and 2.5 ms duration corresponding to energy densities from 1.07 to 3.66 J/cm ² .

12a and 12b compare surface morphologies of copper-based metal conductive inks before and after photoelectromagnetic energy irradiation using a scanning electron microscope (SEM).

Referring to FIG. 12A , before the application of IPL, the surface of the coated copper-based metal conductive ink was only agglomerated metal nanoparticles and crystallized metal oxide. However, referring to Fig. 12B, it is clearly shown that after application of IPL, the metal oxide was reduced to metal, forming a conductive network of thinly sintered copper with a high porosity and three-dimensional structure.

The present invention can be summarized as follows.

1. As an anode electrode for a lithium metal battery having the function of suppressing dendrite growth, maintaining a stable SEI, and enduring the internal stress of lithium metal volume change during repeated charge and discharge cycles,

i. copper current collector layer,

ii. A lithium metal layer disposed on the surface of the current collector layer;

iii. A protective layer having a three-dimensional structure with open cell pores, and

iv. An anode electrode for a lithium metal battery comprising a low melting point lithium alloy metal coating.

2. The lithium metal layer has a surface texture processed to improve adhesion with the protective layer,

The processed surface texture is created by a sandblasting method of shooting abrasive particles on the lithium metal layer,

The anode electrode for a lithium metal battery, characterized in that the abrasive particles include, but are not limited to, at least one of aluminum oxide, pulverized silica and chemically inert soda-lime glass beads.

3. The anode electrode for a lithium metal battery, characterized in that the protective layer is a polymer nanocomposite layer including an open cell nanoporous polymer matrix, a carbon-based conductive nanomaterial and a structural support material.

4. A method of forming a polymer nanocomposite layer having the open-cell nanoporous structure of claim 3,

i. Forming a slurry by mixing the precursor materials of the polymer nanocomposite;

ii. Coating and drying the slurry on a lithium metal layer using a thin film coating method;

iii. A method comprising forming open-cell three-dimensional nanopores by applying photoelectromagnetic energy to evaporate the low-boiling point polymer in the slurry.

5. The mixture of the polymer nanocomposite slurry includes two or more polymers having different boiling points, a conductive carbon additive, a structural support additive, and a solvent;

The two or more polymers having different boiling points include, but are not limited to, polyacrylonitrile (PAN), polytetrafluoroethylene (PTFE), poly(methyl methacrylate) (PMMA), poly(3,4-ethylene) deoxythiophene) polystyrene sulfonate (PEDOT: PSS), polydiacetylene (PDA), polypropylene, polystyrene (PS), polyurethane (PU), polyethylene oxide (PEO), polyethylene terephthalate (PET), styrene-ethylene - selected from butylene-styrene (SEBS), glycerol, sucrose, cellulose and lignin;

The structural support additive includes an electrochemically inert material having high mechanical strength, such as hexagonal boron nitride (hBN), silicon nanowire (SiNW), aluminum oxide, and the like,

The conductive carbon additive is selected from, but is not limited to, single-walled carbon nanotubes (SWCNTs), multi-walled carbon nanotubes (MWCNTs), graphene, graphene oxide, graphene nanoplatelets (GNPs), and carbon dots;

Wherein the solvent is, but is not limited to, water, N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethyl sulfoxide (DMSO), or a combination thereof.

6. The method characterized in that the protective layer comprises a three-dimensional carbon nanofiber mattress having open cell pores.

7. The step of forming the carbon nanofiber mattress having the open-cell nanoporous structure

i. Preparing a nanofiber precursor solution;

ii. electrospinning a polymer nanocomposite nanofiber mattress;

iii. Applying photoelectromagnetic energy to carbonize the polymer nanocomposite nanofibers to form carbon nanofibers, and

iv. hot pressing the polymer nanocomposite nanofiber mattress onto a lithium metal anode.

8. The nanofiber precursor solution comprises a mixture comprising at least one polymer suitable for electrospinning a conductive carbon additive and a solvent;

The polymer includes, but is not limited to, 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) are selected from,

The conductive carbon additive is, but is 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. consists of

The solvent includes, but is not limited to, water, acetone, formic acid, chloroform, isopropanol, N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethyl sulfoxide (DMSO) and tetrahydrofuran (THF) ) A method characterized in that it may include one or more of.

9. The electrospinning step comprises forming a voltage difference between a syringe needle mounted on a syringe pump and a rotating drum using a horizontal electrospinning apparatus having a high voltage power supply.

10. In the step of attaching the carbon nanofiber mattress, the carbon nanofiber mattress is attached to the lithium metal layer by applying both heat and compressive stress,

Heat and compressive stress are applied via, but not limited to, a calendering machine, compression molding machine or hot press.

11. The method characterized in that the protective layer is composed of a network of carbon nanotubes coated with metal oxide and has a three-dimensional structure of open cell pores.

12. The step of generating a network of carbon nanotubes coated with the metal oxide

i. Mixing a lithium-affinity metal oxide and a nanocomposite precursor of lithium-non-affinity carbon nanotubes;

ii. Depositing a nanocomposite of a lithophilic metal oxide and a lithophilic carbon nanotube on a lithium metal layer using a thin film coating;

iii. Forming a network of carbon nanotubes having lithium affinity and lithium non-affinity in a gradient by applying photoelectromagnetic energy,

The upper layer of the network of carbon nanotubes is lithium-incompatible carbon nanotubes and the lower layer is a lithium-affinity metal oxide-carbon nanotube composite.

13. The mixture of the nanocomposite precursor is composed of a lithium-affinity metal oxide that maintains a network structure by attaching carbon nanotubes to a lithium metal anode, and lithium-incompatible carbon nanotubes that form a conductive network,

The lithium-affinity metal oxide may include, but is not limited to, 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 combinations thereof. How to characterize.

14. A current collector having a function of suppressing dendrite growth, maintaining a stable SEI, and enduring the internal stress of lithium metal volume change during repeated charge and discharge cycles,

i. a copper metal current collector layer and

ii. A three-dimensional network structure coated on the copper metal current collector layer,

The current collector, characterized in that the three-dimensional network structure is copper-based or carbon-based.

15. A method of generating an open cell three-dimensional copper-based network structure comprising:

i. Forming a slurry in which copper, silver, a conductive carbon additive, a polymer carrier, and a solvent are mixed;

ii. depositing the slurry on a copper metal layer using a thin film coating; and

iii. and optoelectronically sintering the deposited slurry to form a three-dimensional copper-based network structure.

16. The slurry includes copper-based nanoparticles, a silver salt, a polymer carrier, a conductive carbon additive and a solvent;

The copper-based nanoparticles are, but are not limited to, nanoparticles selected from one or more of copper, copper acetate, copper oxide, and copper formate tetrahydrate,

The silver salt is, but is not limited to, one or more selected from among silver, silver nitrate, silver nitrite and silver acetate,

The polymeric carrier includes polyvinylpyrrolidone dissolved in polyethylene glycol,

The conductive carbon additive is characterized in that at least one selected from carbon black, single-walled carbon nanotubes, multi-walled carbon nanotubes, functionalized carbon nanotubes, graphene and graphene nanoplatelets.

17. The step of generating the open cell, three-dimensional carbon-based network structure

i. mixing a carbon precursor, a conductive carbon additive and a solvent to form a slurry;

ii. depositing a slurry on the copper metal layer using a thin film coating;

iii. and applying photoelectromagnetic energy to carbonize the slurry and form a three-dimensional carbon-based network structure.

18. The mixture includes one or more carbon precursors, a conductive carbon additive, and a solvent;

The carbon precursor includes industrial by-products such as asphaltenes, mesophase pitch, cellulose, cellulose nanocrystals and lignin;

Wherein the conductive carbon additive is composed of carbon black, single-walled carbon nanotubes, multi-walled carbon nanotubes, functionalized carbon nanotubes, graphene, graphene nanoplatelets, or combinations thereof.

19. The low-melting lithium alloy metal coating layer has self-healing ability and is applied to the lithium metal anode surface, its protective coating layer or anode-free current collector to stabilize the SEI layer.

20. The method of producing the lithium alloy metal coating layer on the protective coating layer of the lithium metal anode,

Adding pulverized powder of lithium alloy metal on a lithium metal layer, a protective coating layer or an anode-free current collector;

and applying photoelectromagnetic energy to sinter a thin lithium alloy metal to a lithium target surface.

21. The pulverized powder includes one or more low melting point lithium alloy metals and metalloids,

wherein the low melting point lithium alloy metals and metalloids are selected from, but are not limited to, indium, tin, bismuth, gallium, silver, gold, zinc, aluminum, platinum, germanium and fields metals.

22. Deposition of the material using the thin film coating

coating the slurry mixture of nanocomposite material with a film coater, which can be a wire coater or a blade coater;

drying the coated slurry in a vacuum oven to evaporate all solvents in the slurry.

23. The application of photoelectromagnetic energy evaporates low-boiling materials, induces carbonization of polymers and carbon precursor materials, and sinters conductive metal nanoparticles;

The application of photoelectromagnetic energy applies high energy in a short time, and the applied energy is absorbed with a high absorption rate by the carbon additive,

The application of photoelectromagnetic energy applies energy only to the surface to be irradiated,

The application of the opto-electromagnetic energy uses IPL (Intensive Pulsed Light), microwave, laser, plasma or irradiation through an infrared oven.

24. A cooling device for cooling the substrate during application of opto-electromagnetic energy,

The cooling device lowers the temperature of the substrate by contacting a material under direct irradiation of photoelectromagnetic energy, such as a lithium metal layer or a copper current collector layer, to prevent excessive heat from damaging the substrate;

The cooling device is

i. a holder plate comprising a thermally conductive metal;

ii. A cooling device comprising a heat exchanger system such as a Peltier element or a heat exchanger system in which a refrigerant is pumped through the holder plate into the heat exchanger.

25. The holder plate includes a metal plate with an extruded fixture to fit a lithium metal anode of a specified size, the metal plate being thick enough to hold a heat exchanger system, and the material of the metal plate including, but not limited to, copper or a thermally conductive metal comprising aluminum.

Claims (25)

As an anode electrode for a lithium metal battery,
current collector;
a lithium metal layer disposed on the current collector;
a protective coating layer having a three-dimensional structure disposed on the lithium metal layer and having open cell pores; and
A lithium alloy metal coating layer disposed on the surface of the protective coating layer,
The protective coating layer is an anode electrode for a lithium metal battery, characterized in that the polymer nanocomposite layer comprising an open cell nanoporous polymer matrix, a carbon-based conductive additive and a structural support additive.
According to claim 1,
The lithium metal layer is an anode electrode for a lithium metal battery, characterized in that it has a processed surface texture.
As an anode electrode for a lithium metal battery,
current collector;
a lithium metal layer disposed on the current collector;
a protective coating layer having a three-dimensional structure disposed on the lithium metal layer and having open cell pores; and
A lithium alloy metal coating layer disposed on the surface of the protective coating layer,
The protective coating layer includes a network of carbon nanotubes with a lithium-affinity metal oxide having a three-dimensional structure of open cell pores,
An anode electrode for a lithium metal battery, characterized in that the upper layer of the network of carbon nanotubes is lithium-affinity carbon nanotubes and the lower layer is a lithium-affinity metal oxide-carbon nanotube composite.
According to claim 3,
The anode electrode for a lithium metal battery, characterized in that the lithium-affinity metal oxide comprises at least one of zinc oxide, iron oxide, manganese oxide and titanium oxide.
According to claim 1,
The lithium alloy metal is an anode electrode for a lithium metal battery, characterized in that selected from indium, tin, bismuth, gallium, silver, gold, zinc, aluminum, platinum, germanium and fields metal.
As a method for manufacturing an anode electrode for a lithium metal battery,
disposing a lithium metal layer on the current collector;
forming a three-dimensional protective coating layer having open cell pores on the lithium metal layer; and
Forming a lithium alloy metal coating layer on the surface of the protective coating layer,
At least one step of the protective coating layer forming step and the lithium alloy metal coating layer forming step comprises the step of irradiating photoelectromagnetic energy.
According to claim 6,
Forming the protective coating layer
Generating a slurry in which a first polymer, a second polymer having a lower boiling point than the first polymer, a carbon-based conductive additive, a structural support additive, and a solvent are mixed;
coating the slurry on the lithium metal layer by a thin film coating method and then drying to form an intermediate coating layer;
Method for manufacturing an anode electrode for a lithium metal battery, characterized in that by irradiating photoelectromagnetic energy to the intermediate coating layer to evaporate the second polymer in the intermediate coating layer to form nanopores.
According to claim 7,
The first polymer and the second polymer are polyacrylonitrile (PAN), polytetrafluoroethylene (PTFE), poly(methyl methacrylate) (PMMA), poly(3,4-ethylene dioxythiophene) polystyrene sulfone. nate (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 carbon-based conductive additive is selected from single-walled carbon nanotubes (SWCNTs), multi-walled carbon nanotubes (MWCNTs), graphene, graphene oxide, graphene nanoplatelets (GNPs), and carbon dots,
The structural support additive is a method for manufacturing an anode electrode for a lithium metal battery, characterized in that selected from hexagonal boron nitride (hBN), silicon nanowire (SiNW) and aluminum oxide.
According to claim 6,
Forming the protective coating layer
Preparing a nanofiber precursor solution;
electrospinning the nanofiber precursor solution into a polymer nanocomposite nanofiber mattress;
Applying photoelectromagnetic energy to carbonize the polymer nanocomposite nanofibers to form a carbon nanofiber mattress;
A method for manufacturing an anode electrode for a lithium metal battery, comprising the step of attaching a carbon nanofiber matrix to a lithium metal anode.
According to claim 9,
The nanofiber precursor solution includes a polymer, a carbon-based conductive additive and a solvent,
The polymer is 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), polychlorinated At least one of vinyl (PVC), polyvinylpyrrolidone (PVP), collagen and cellulose acetate (CA),
The carbon-based conductive additive includes at least one of single-walled carbon nanotubes (SWCNTs), multi-walled carbon nanotubes (MWCNTs), graphene, graphene oxide, graphene nanoplatelets (GNPs), and carbon dots,
The solvent is at least one of water, acetone, formic acid, chloroform, isopropanol, N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethyl sulfoxide (DMSO) and tetrahydrofuran (THF) Method for manufacturing an anode electrode for a lithium metal battery comprising a.
According to claim 9,
In the step of attaching the carbon nanofiber mattress, the carbon nanofiber mattress is attached to the lithium metal layer by applying both heat and compressive stress,
A method for manufacturing an anode electrode for a lithium metal battery, characterized in that heat and compressive stress are applied through a calendering machine, a compression molding machine or a hot press.
According to claim 6,
Forming the protective coating layer
Mixing a nanocomposite precursor of a lithium-affinity metal oxide and a lithium-non-affinity carbon nanotube;
depositing a nanocomposite of a lithophilic metal oxide and a lithophilic carbon nanotube on a lithium metal layer using a thin film coating;
Forming a network of carbon nanotubes having lithium affinity and lithium non-affinity in a gradient by applying photoelectromagnetic energy,
The method of manufacturing an anode electrode for a lithium metal battery, characterized in that the upper layer of the network of carbon nanotubes is lithium-affinity carbon nanotubes and the lower layer is a lithium-affinity metal oxide-carbon nanotube composite.
According to claim 6,
Forming the lithium alloy metal coating layer is
disposing a lithium alloy metal in powder form on the protective coating layer;
Allowing lithium alloy metal in powder form to flow into the protective coating layer through a calendering process;
Melting the lithium alloy metal in powder form by irradiating photoelectromagnetic energy;
A method for manufacturing an anode electrode for a lithium metal battery, characterized in that the lithium alloy metal melted by capillary action is coated on the surface of the protective coating layer.
According to claim 6,
A method for manufacturing an anode electrode for a lithium metal battery, further comprising forming a processed surface texture on the lithium metal layer using sandblasting.
As a method for manufacturing an anode electrode for a lithium metal battery,
Forming a slurry in which at least one metal nanoparticle precursor, a carbon-based conductive additive, a polymer carrier, and a solvent are mixed;
depositing the slurry on a metal current collector using a thin film coating; and
Sintering the deposited slurry by irradiating photoelectromagnetic energy;
Method for manufacturing an anode electrode for a lithium metal battery, characterized in that a three-dimensional metal-based network structure is formed by sintering the slurry using the photoelectromagnetic energy irradiation.
According to claim 15,
The metal nanoparticle precursor includes a copper-based nanoparticle precursor,
The copper-based nanoparticle precursor is a method for manufacturing an anode electrode for a lithium metal battery, characterized in that at least one selected from copper, copper acetate, copper oxide and copper formate tetrahydrate.
According to claim 15,
Method for manufacturing an anode electrode for a lithium metal battery, further comprising the step of electroplating lithium on the metal current collector on which the three-dimensional metal-based network structure is formed.
As a method for manufacturing an anode electrode for a lithium metal battery,
mixing a carbon precursor, a carbon-based conductive additive, and a solvent to form a slurry;
depositing a slurry on a metal current collector using a thin film coating; and
A method for manufacturing an anode electrode for a lithium metal battery, comprising carbonizing the deposited slurry using photoelectromagnetic energy and forming a three-dimensional carbon-based network structure.
According to claim 18,
The carbon precursor is an anode electrode manufacturing method for a lithium metal battery, characterized in that selected from asphaltenes, mesophase pitch, cellulose, cellulose nanocrystals and lignin.
According to claim 18,
Method for manufacturing an anode electrode for a lithium metal battery, further comprising the step of electroplating lithium on the metal current collector on which the three-dimensional carbon-based network structure is formed. delete delete delete delete delete

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