Anodeless lithium secondary battery, lithium metal secondary battery, lithium secondary battery, and all-solid-state secondary battery comprising metal glass coating layer

Abstract

The present invention relates to an anodeless lithium secondary battery, lithium metal secondary battery, lithium secondary battery, and all-solid-state secondary battery which comprise a Zr-based metal glass and Ti-based metal glass coating layer capable of suppressing the generation of a solid-electrolyte interface and dead lithium that form at the interface between a Cu current collector and an electrolyte and reduce the coulombic efficiency of an anodeless lithium battery. The anodeless lithium secondary battery comprising a metal glass coating layer according to the present invention is characterized by including: a positive electrode; a current collector facing the positive electrode and made of copper foil; an electrolyte positioned between the positive electrode and the current collector; and a separator separating the positive electrode and the current collector, wherein the interface at which the current collector contacts the electrolyte is coated with metal glass<sb / >.

Description

Non-anode lithium secondary battery, lithium metal secondary battery, lithium secondary battery and all-solid-state secondary battery having a metal glass coating layer

[0001] The present invention relates to a non-anode lithium secondary battery, a lithium metal secondary battery, a lithium secondary battery and an all-solid-state secondary battery having a metallic glass coating layer, and more particularly, to a non-anode lithium secondary battery, a lithium metal secondary battery, a lithium secondary battery and an all-solid-state secondary battery having a metallic glass coating layer capable of suppressing the formation of a solid-electrolyte interface and dead lithium on the surface of a negative electrode current collector by coating a metallic glass, for example, a Zr-based, Mo-based or Ti-based metallic glass, on the interface where a Cu current collector comes into contact with an electrolyte.

[0002] High energy density is a key factor in achieving the driving range of electric vehicles comparable to that of internal combustion engine vehicles and extending the operating time of electronic devices. To achieve high energy density, numerous attempts have been made to modify the cell structure of lithium-ion batteries to achieve higher specific capacities and smaller volumes or weights. Anode-free lithium metal batteries have been considered a promising cell structure for improving the energy density of lithium-ion batteries. Anode-free lithium metal batteries, which lack anode active materials such as graphite, can reduce battery weight, volume, and cost compared to commercial lithium-ion batteries. However, the absence of anode active materials leads to a decrease in Coulombic efficiency. Low Coulombic efficiency is a major drawback for the commercialization of anode-free lithium metal batteries, and numerous attempts have been made to overcome this drawback. The low Coulombic efficiency is primarily due to excessive consumption of lithium and electrolyte due to the unstable solid-electrolyte interface (SEI) and the formation of dead lithium. The unstable SEI and dead lithium lead to uneven lithium deposition or the formation of lithium dendrites on the negative current collector during charging, which results in uneven current density on the current collector (CC). The uneven surface conditions of the current collector and the inherent lithiophobicity of copper (Cu) accelerate uneven lithium deposition. The submillimeter-level roughness of bare copper induced during the foil manufacturing process leads to uneven lithium deposition. Furthermore, nanometer-level roughness caused by defects such as grain boundaries and impurities, as well as variations in the crystal orientation of particles within the current collector, induce uneven current density and thus uneven lithium deposition. In addition to the various surface conditions, the lithiophobicity of Cu leads to uneven lithium deposition. Cu is known to be a relatively semi-lithiating material based on its solid solution and compound forming properties.Elements that exhibit lithium solubility and form compounds with lithium, such as gold (Au) and silver (Ag), have been reported to be lithiophilic. On the other hand, copper exhibits antilithiation behavior because it is insoluble in lithium and does not exhibit intermetallic alloying with lithium. In the initial stage of lithium deposition, lithium nuclei are formed in the protruding surface region, where the current density is higher than that of the surrounding region. Thereafter, lithium ions prefer to deposit on the pre-deposited lithium rather than on the surface of the bare Cu current collector due to its antilithiation. This results in an uneven top surface of the deposited lithium and the growth of lithium dendrites.

[0003] The undulating top surface of the deposited lithium increases the interfacial area between the electrolyte and the deposited lithium and accelerates the formation of a solid-electrolyte interface, which reduces the Coulombic efficiency. The solid-electrolyte interface is formed at the interface between the deposited lithium metal and the electrolyte. During cycling, as lithium ions repeatedly deposit and de-deposit on the current collector, the morphology of the deposited lithium changes. This causes cracks to form in the solid-electrolyte interface, continuously exposing the deposited lithium to the electrolyte. The solid-electrolyte interface continues to form during cycling, consuming lithium and electrolyte. In addition to the lithium consumption caused by the solid-electrolyte interface formation, the formation of lithium fragments also reduces the Coulombic efficiency. Lithium fragments are electrochemically inactive because they are lithium dendrites separated from the deposited lithium. Lithium dendrites prefer to form at locations with high local current density, depending on the time of the sand. During lithium desorption, uneven dissolution leads to the formation of lithium fragments, known as dead lithium. Another disadvantage of lithium dendrite formation is that it can cause short circuits. If lithium dendrites continue to grow, they will eventually contact the anode, causing a short circuit.

[0004] Many attempts have been made to improve the Coulombic efficiency of anode-free lithium metal batteries. Among these, coating the current collector with various thin films has been evaluated. The coating layer on the current collector primarily consists of three types of materials: carbon-based, organic-based, and metallic. Among these, the advantages of metallic materials include excellent electrical conductivity and strong adhesion to the Cu current collector. The metal coating layer acts as a protective layer, preventing corrosion and significant volume change of the current collector during cycling. Various metals have been investigated as coating layers on the current collector, and it has been demonstrated that lithiophilic metal layers, such as silver (Ag), gold (Au), and tin (Sn), promote uniform lithium deposition. During lithium deposition, the coated metal dissolves in the deposited lithium, forming a solid solution layer, effectively reducing the nucleation overpotential. Not only lithiophilic metals but also antilithiophilic compounds have been employed as coating layers. The chemical reaction between lithium and the nanostructured antilithiophilic material leads to an antilithiophilic-to-lithiophilic conversion, which enhances electrochemical performance.

[0005] In order to solve the above problems, the present invention provides a non-anode lithium secondary battery, a lithium metal secondary battery, a lithium secondary battery, and an all-solid-state secondary battery having a coating layer of one or more kinds selected from a Zr-based metallic glass, a Mo-based metallic glass, and a Ti-based metallic glass capable of suppressing the formation of a solid-electrolyte interface formed at the interface between a Cu negative electrode current collector and an electrolyte, which lowers the coulombic efficiency of the non-anode lithium battery, and a mixture of two or more kinds thereof.

[0006] In order to achieve the above-described object, a non-anode lithium secondary battery having a metallic glass coating layer according to the first embodiment of the present invention comprises: a cathode; an anode current collector facing the cathode and made of copper foil; an electrolyte positioned between the cathode and the anode current collector; and a separator separating the cathode and the anode current collector; wherein an interface where the current collector comes into contact with the electrolyte is made of metallic glass. It is characterized by being coated.

[0007] In addition, a lithium metal secondary battery having a metallic glass coating layer according to a second embodiment of the present invention includes: a positive electrode; a lithium metal negative electrode positioned facing the positive electrode; an electrolyte positioned between the positive electrode and the lithium metal negative electrode; and a separator separating the positive electrode and the lithium metal negative electrode; wherein the surface of the lithium metal negative electrode is characterized in that it is coated with metallic glass.

[0008] In addition, a lithium secondary battery having a metallic glass coating layer according to a third embodiment of the present invention includes: a positive electrode; a lithium metal negative electrode positioned facing the positive electrode; a negative electrode current collector made of copper foil that is in contact with the lithium metal negative electrode and positioned in a direction opposite to the positive electrode; an electrolyte positioned between the positive electrode and the lithium metal negative electrode; and a separator that separates the positive electrode and the lithium metal negative electrode; wherein the surface of the lithium metal negative electrode is characterized in that it is coated with metallic glass.

[0009] In addition, an all-solid-state secondary battery having a metal glass coating layer according to a fourth embodiment of the present invention includes a positive electrode; a negative electrode positioned facing the positive electrode; and a solid electrolyte filled between the positive electrode and the negative electrode; characterized in that an interfacial layer of a metal glass layer is formed between the solid electrolyte and the negative electrode.

[0010] In addition, the current collector according to the fifth embodiment of the present invention is characterized in that it is a negative current collector whose surface is coated with metallic glass.

[0011] In addition, a secondary battery according to a sixth embodiment of the present invention is characterized by including a metallic glass thin film formed between an electrolyte and a negative electrode current collector, between an electrolyte and a lithium metal negative electrode, or between an electrolyte and a separator. Here, the secondary battery uses a liquid electrolyte.

[0012] In addition, the secondary battery according to the seventh embodiment of the present invention is characterized by including a metallic glass thin film present between the electrolyte and the negative electrode current collector or between the electrolyte and the lithium metal negative electrode. Here, the secondary battery uses a solid electrolyte.

[0013] In addition, a method for manufacturing a non-anode lithium secondary battery having a metallic glass coating layer according to the eighth embodiment of the present invention is a method for manufacturing a non-anode lithium secondary battery including: a positive electrode; an anode current collector facing the positive electrode and made of copper foil; an electrolyte positioned between the positive electrode and the negative electrode current collector; and a separator separating the positive electrode and the negative electrode current collector; wherein the negative electrode current collector is characterized by coating metallic glass on a copper thin film by magnetron sputtering.

[0014] In the first to eighth embodiments, a portion of the interface layer or the metallic glass thin film coated with metallic glass is crystallized during charging and discharging.

[0015] In the first to eighth embodiments, the metallic glass contains at least two different elements.

[0016] The above metallic glass contains a component represented by the following formula 1.

[0017] (Am1) n1 + (Am2) n2 + (Am3) n3 + ····· + (Amx) ny (Formula 1)

[0018] Here, Am1, Am2, Am3, ····· , Amx represent different metallic glass elements, x is an integer greater than or equal to 2, more preferably x is an integer greater than or equal to 2 and less than or equal to 30, y is an integer greater than or equal to 2 and less than or equal to 30, and n1 > 0, n2 > 0, n3 ≥ 0, ····· , ny ≥ 0 and n1 + n2 + ····· + ny = 100.

[0019] For example, if the metallic glass is composed of two elements, it is represented by the following equation 1-1.

[0020] (Am1) n1 + (Am2) n2 (Formula 1-1)

[0021] Here, Am1 and Am2 represent different metallic glass elements, and satisfy n1 > 0, n2 > 0, n3 = 0, ····· , ny = 0, and n1 + n2 = 100.

[0022] Alternatively, if the metallic glass is composed of four elements, it is represented by the following equation 1-2.

[0023] (Am1) n1 + (Am2) n2 + (Am3) n3 + (Am4) n4 (Formula 1-2)

[0024] Here, Am1, Am2, Am3, and Am4 represent different metallic glass elements, and satisfy n1 > 0, n2 > 0, n3 > 0, n4 > 0, n5 = 0, ····· , ny = 0, and n1 + n2 + n3 + n4 = 100.

[0025] The metallic glass containing the component represented by the above formula 1 satisfies the enthalpy relationship of the following formula 2, △H total ≥ 0 In the process of manufacturing an amorphous alloy powder or metallic glass powder, the amorphous alloy powder or metallic glass powder more easily undergoes a phase transformation into a crystalline phase, and thus the effect of the present invention is not obtained.

[0026] △H total = △H 12 + △H 13 + △H 14 + ····· + △H 1x

[0027] + △H 23 + △H 24 + ····· + △H 2x

[0028] + △H 34 + ····· + △H 3x

[0029] + ····· + △H (x-1)x < 0 (Equation 2)

[0030] Here, △H (x-1)x represents the mixture series of elements Am(x-1) and Am(x). For example, the mixture series of elements in the above equation 2 is defined as follows.

[0031] △H 12 : Mixing heat of Am1 and Am2 elements

[0032] △H 13 : Mixing heat of Am1 and Am3 elements

[0033] △H 14 : Mixing heat of Am1 and Am4 elements

[0034] △H 1x : Mixing heat of Am1 and Amx elements

[0035] △H 23 : Mixing heat of Am2 and Am3 elements

[0036] △H 24 : Mixing heat of Am2 and Am4 elements

[0037] △H 2x : Mixing heat of Am2 and Amx elements

[0038] △H 34 : Mixing heat of Am3 and Am4 elements

[0039] △H 3x : Mixing heat of Am3 and Amx elements

[0040] For example, if the metallic glass is composed of three elements, it is represented by the following equation 2-1.

[0041] △H total = △H 12 + △H 13

[0042] + △H 23 < 0 (Formula 2-1)

[0043] The above metallic glass is composed of lanthanum (La), cerium (Ce), praseodymium (Pr), promethium (Pm), samarium (Sm), lutetium (Lu), yttrium (Y), neodymium (Nd), gadolinium (Gd), terbium (Tb), dysprosium (Dy), hormium (Ho), erbium (Er), thulium (Tm), thorium (Th), calcium (Ca), scandium (Sc), barium (Ba), beryllium (Be), bismuth (Bi), rubidium (Rb), germanium (Ge), lead (Pb), ytterbium (Yb), chromium (Cr), strontium (Sr), europium (Eu), zirconium (Zr), thallium (Tl), lithium (Li), hafnium (Hf), magnesium (Mg), phosphorus (P), arsenic (As), iron (Fe), It is characterized by being a mixture of two or more elements selected from palladium (Pd), gold (Au), plutonium (Pu), cobalt (Co), gallium (Ga), tungsten (W), germanium (Ge), silver (Ag), sodium (Na), molybdenum (Mo), nickel (Ni), aluminum (Al), copper (Cu), zinc (Zn), antimony (Sb), silicon (Si), tin (Sn), titanium (Ti), cadmium (Cd), indium (In), platinum (Pt), and mercury (Hg).

[0044] The glass transition temperature of the above metallic glass powder is characterized by being 100°C or higher.

[0045] In the first to eighth embodiments, the metallic glass is one or both of Zr-based metallic glass and Ti-based metallic glass, and may include, for example, any one of Zr-Al-Ni, Zr-Al-Cu-Ni, Zr-Al-Cu-Ni-Ti, and Zr-Be-Cu-Ni-Ti metallic glass.

[0046] In the first to eighth embodiments, the Zr-based metallic glass is Zr x Cu y Ni z Al wA compound, wherein x is in the range of 35 to 70, y is in the range of 20 to 50, z is in the range of 7 to 15, and w is in the range of 3 to 5, and more preferably x is in the range of 40 to 50, y is in the range of 25 to 35, z is in the range of 10 to 13, and w is in the range of 4 to 5.

[0047] In the first to eighth embodiments, the metallic glass is a Mo-based metallic glass, and the Mo-based metallic glass may include any one of Mo-Zr, Mo-Zr-Ti, Mo-Zr-Ti-Si, Mo-Zr-Co, Mo-Zr-Co-Si, Mo-Ru-B, Mo-Ni-Si-B, Mo-Si-Ta-Zr-Fe-Co-Y, and Mo-Co-B metallic glasses.

[0048] In the first to eighth embodiments, the Mo-based metallic glass is Mo a Zr b Co c Si d It is a compound, and a is in the range of 15 to 85, b is in the range of 20 to 50, c and d are in the range of 5 to 10, and more preferably a is in the range of 60 to 70, b is in the range of 22 to 28, and c and d are in the range of 8 to 10.

[0049] In the first to eighth embodiments, the Mo-based metallic glass is Mo a Zr b Ti c Si d It is a compound, and a is in the range of 15 to 85, b is in the range of 20 to 50, c and d are in the range of 5 to 10, and more preferably a is in the range of 60 to 70, b is in the range of 22 to 28, and c and d are in the range of 8 to 10.

[0050] In the first to eighth embodiments, the metallic glass is a Ti-based metallic glass, and the Ti-based metallic glass is Ti-Cu, Ti-Cu-Al, Ti-Cu - It may include one of Nb, Ti-Cu-Ni, Ti-Cu-Ni-Sn, Ti-Cu-Ni-Sn-Zr, Ti-Cu-Ni-Zr, Ti-Cu-Ni-Sn-Zr, and Ti-Zr-Si metallic glasses.

[0051] In the first to eighth embodiments, the Ti-based metallic glass is Ti a Zr b Si c It is a compound, and a is in the range of 45 to 85, b is in the range of 20 to 50, and c is in the range of 5 to 10, and more preferably a is in the range of 60 to 70, b is in the range of 22 to 28, and c is in the range of 8 to 10.

[0052] In the first to eighth embodiments, the coating thickness of the metallic glass is 5 to 500 nm, preferably 8 to 200 nm, more preferably 10 to 50 nm, and most preferably 10 to 20 nm.

[0053] The spike voltage of the above negative electrode collector is characterized by being 50 mV to 100 mV.

[0054] The above-mentioned negative electrode current collector is characterized in that its nuclear growth overpotential is 10 mV to 20 mV.

[0055] SEI resistance (R) of the coating layer of the above metallic glass SEI ) is 10 Ω to 100 Ω, and the charge transfer resistance ( Rct ) is characterized by being 50 Ω to 200 Ω.

[0056] As described above, the present invention has the effect of suppressing the solid-electrolyte interface and the generation of dead lithium in half-cells and full-cells of a non-anode lithium secondary battery, thereby exhibiting promising cycling performance.

[0057] Figure 1(a) shows the coulombic efficiency of a half-cell in which the negative current collector is coated with Mo-MG thin films having thicknesses of 5 nm, 10 nm, 15 nm, 20 nm, and 25 nm, Figure 1(b) shows the voltage hysteresis of a half-cell in which the negative current collector is coated with Mo-MG thin films having thicknesses of 5 nm, 10 nm, 15 nm, 20 nm, and 25 nm, and Figure 1(c) shows the voltage profile at each cycle. Figure 1(d) shows the Nyquist plots of bare Cu and 10 nm and 20 nm thick Zr-MG coated negative electrode collectors after the first discharge cycle after the preliminary cycle, as measured by electrochemical impedance spectroscopy (EIS), and Figure 1(e) shows the voltage plots measured while charge-discharge was repeatedly performed in a symmetric cell in which two 10 nm, 15 nm, and 20 nm thick Zr-MG coated lithium metal negative electrodes were arranged facing each other with a separator in between.

[0058] Figure 2(a) shows the coulombic efficiency of the half-cells with the negative current collector coated with 10 nm, 15 nm, and 20 nm thick Mo-MG films, Figure 2(b) shows the voltage hysteresis of the half-cells with the negative current collector coated with 10 nm, 15 nm, and 20 nm thick Mo-MG films, and Figure 2(c) shows the 0.1 mA cm of the half-cells with the coated current collector. -2 0.5 mAh cm at a current density -2 It represents the overpotential measured at the capacity.

[0059] Figure 3(a) shows the coulombic efficiency of a half-cell in which the negative current collector is coated with Ti-MG thin films having thicknesses of 5 nm, 10 nm, 15 nm, and 20 nm, Figure 3(b) shows the voltage profile at each cycle, and Figure 3(c) shows a voltage graph measured while charge-discharge was repeatedly performed in a symmetric cell in which two lithium metal negative electrodes coated with Ti-MG having thicknesses of 5 nm, 10 nm, 15 nm, and 20 nm were arranged facing each other with a separator in between.

[0060] The present invention is susceptible to various modifications and embodiments. Specific embodiments are illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, but rather to encompass all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention. Throughout the description of each drawing, similar reference numerals have been used to designate similar components.

[0061] Terms such as first, second, A, and B may be used to describe various components, but these components should not be limited by these terms. These terms are used solely to distinguish one component from another.

[0062] For example, without departing from the scope of the present invention, the first component could be referred to as the second component, and similarly, the second component could also be referred to as the first component. The term "and / or" includes any combination of a plurality of related listed items or any one of a plurality of related listed items.

[0063] When a component is referred to as being "connected" or "connected" to another component, it should be understood that it may be directly connected or connected to that other component, but that there may be other components intervening. Conversely, when a component is referred to as being "directly connected" or "connected" to another component, it should be understood that there are no other components intervening.

[0064] The terminology used in this application is only used to describe specific embodiments and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, it should be understood that the terms "comprise" or "have" indicate the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0065] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0066]

[0067] In the present invention, Mo is used as a coating for the Cu collector. 56 Zr 23 Ti 10 Si 11 , Mo 58 Zr 22Co. 10 And 10 , You 45 With 41Molybdenum-based and Ti-based metallic glasses, such as Ni9Zr5, were used, significantly improving the electrochemical performance of anode-free lithium metal batteries. Molybdenum-based and Ti-based metallic glass thin films, several nanometers to several tens of nanometers thick, were deposited using a magnetron sputtering process. Metallic glasses exhibit glass-like behavior during heating. Their amorphous structure offers numerous advantages for enhancing the electrochemical properties of current collectors. First, amorphous materials lack long-range order, providing a homogeneous environment for lithium deposition because they are free of defects such as grain boundaries, dislocations, and stacking faults. This eliminates atomic-level roughness, crystallographic orientation, and compositional variations. The short- to medium-range order in Mo-MG (Mo-Metallic Glass) and Ti-MG (Ti-Metallic Glass) thin films results in chemical and physical uniformity on the surface, leading to uniform lithium deposition during charging. Second, the amorphous structure possesses a disordered phase with numerous atomic vacancies and exhibits higher elasticity than crystalline alloys, providing more lithium ion intercalation sites. More lithium insertion sites provided a lithiophilic environment, and the inserted lithium converted Mo-MG and Ti-MG into lithiophilic phases. Mo and Ti, the main components of Mo-MG and Ti-MG, are classified as antilithiating elements due to their poor solubility in lithium and lack of intermetallic formation with lithium. However, excellent cell performance was observed in the Mo-MG and Ti-MG-coated negative current collectors and lithium negative electrodes. Generally, metallic glasses are mainly considered as structural materials because they exhibit excellent mechanical properties such as mechanical strength and elasticity. The research community of metallic glasses has mainly focused on the mechanical properties and glass-forming ability of metallic glasses. To the best of our knowledge, metallic glasses have not been considered as a coating for current collectors until now. The lithiophilic thin films, which are manifested by atomic-level uniformity, a large number of atomic vacancies, excellent elasticity, and a disordered atomic structure, lead to the uniform deposition of lithium on the current collector.The uniform deposition of lithium in the early stage of deposition ultimately leads to excellent electrochemical performance at the solid-electrolyte interface resistance (R. SEI ) and charge transfer resistance (R ct ) was drastically reduced.

[0068] The Coulombic efficiency of half-cells having current collectors coated with Mo-MG and Ti-MG thin films with various thicknesses ranging from 5 nm to 25 nm was analyzed to optimize the thickness of the coating layer. As shown in Fig. 1(a), Fig. 2(a), and Fig. 3(a), the Coulombic efficiency was improved by depositing Mo-MG and Ti-MG layers on the current collectors compared to the uncoated current collectors. The current collectors coated with Mo-MG and Ti-MG thin films with thicknesses of 10 nm and 20 nm showed stable and higher Coulombic efficiency than the uncoated or thinner or thicker Mo-MG and Ti-MG thin films. In the half-cells, 10 nm of Mo 56 Zr 23 Ti 10 Si 11 , 15nm of Mo 58 Zr 22 Co 10 Si 10 , 20nm Ti 45 Cu 41 The Coulombic efficiencies (average Coulombic efficiency over 100 cycles) of the Ni9Zr5 coated collectors at the 100th cycle are 96.98% (96.8±1.4%), 91.5% (96.1±1.5%), and 98.8% (97.8±1.2%), respectively (see Tables 1, 2, and 3).

[0069] MoZrTiSi bare Cu5nm10nm15nm20nm25nm100 th CE67.796.996.993.291.394.0Average CE92.4±798.2±0.596.8±1.495.7±1.995.9±1.596.8±1.5

[0070] MoZrCoSi bare Cu10 nm15 nm20 nm100 thCE41.575.091.587.2Average CE85.5±17.392.3±5.296.1±1.595.6±2.7

[0071] TiCuNZr bare Cu5 nm10 nm15 nm20 nm25 nm30 nm100 th CE47.591.889.697.698.898.297.8Average CE89.9±12.596.1±1.695.5±2.197.2±0.597.8±1.297.4±1.697.4±1.4

[0072] (unit %)

[0073] The higher the average Coulombic efficiency and the narrower its standard deviation, the more stable the cycle performance was demonstrated. It was determined that Mo-MG and Ti-MG with a thickness of 9 nm or less were not sufficient to improve the cycle performance. Mo-MG and Ti-MG layers thicker than 20 nm can increase the internal electrical resistance and deteriorate the electrochemical performance of the current collector. The corresponding voltage profiles of the half-cells in the first cycle of Figs. 1(c) and 2(c) also show that the reason for the somewhat lower capacity in the first cycle appears to be the increased resistance due to the coating. Their voltage hysteresis (Figs. 1(b), 2(b), and 3b) confirms that the low hysteresis voltage was maintained due to the Mo-MG and Ti-MG coating. When the thickness was thinner or thicker than the thickness that showed the highest capacity, the voltage increased rapidly as the cycle progressed. The increase in the hysteresis voltage was closely correlated with the decrease in the Coulombic efficiency of Fig. 1(a). Based on the Coulombic efficiency and voltage history data, the optimal thickness for the coating layer on the collector was in the range of 10 nm to 20 nm.

[0074] The Mo-MG coating explicitly changed the overpotential measured during lithium deposition in the first cycle. The overpotential is a measurable physical parameter for lithium nucleation and growth on the collector and is obtained from the voltage measured over time under a constant current. The overpotential curve shows a deep spike followed by a stabilization region. The overpotential for lithium nucleation on the collector is the sum of charge transfer, diffusion, reaction, and crystallization overpotentials. Alternatively, the electrode polarization during lithium deposition on the collector can be considered as the sum of two terms: the nucleation overpotential (η), which is observed as a voltage spike associated with the nucleation of lithium clusters in the early stage of deposition. n ) and the growth overpotential (η) that describes the growth of lithium from the existing lithium nucleus and is observed as a nearly flat voltage profile. p) is. The spike voltage of the Mo-MG coated collector (Mo-CC) is 63–69 mV, which is about 40 mV lower than the voltage of the bare collector (108 mV). The growth overpotential of Mo-CC measured at 5 hours of deposition is 13 mV, which is lower than 26 mV of the bare collector. The nucleation overpotential, which is the difference between the spike potential and the growth potential of Mo-CC and the bare collector, is 50–56 mV and 82 mV, respectively. It can be seen that the overall overpotential is reduced by depositing the metallic glass film on the collector. Compared to the overpotential values, the shapes of the overpotential curves were clearly different. After the voltage spike, the voltage of Mo-CC rapidly increased and saturated after 1 hour of deposition. In the case of bare Cu, the voltage continued to increase for up to 5 hours without saturation. The difference should be caused by the difference in the four overpotentials between the bare collector and Mo-CC. Among the four overpotentials, charge transfer, diffusion, and crystallization overpotentials are expected to primarily cause differences in the overpotential profiles. This is because the chemical reactions before and after lithium deposition are not expected to differ significantly, regardless of the presence of a current collector coating. The differences in the overpotentials for charge transfer, diffusion, and crystallization at the Li / Cu interface deposited in the nucleation regime and the Li / Mo-CC interface deposited in the growth regime are due to differences in the interfacial properties and the morphological differences in lithium deposition in the growth regime. Based on the overpotential profiles, once lithium ions begin to deposit on the Mo-CC, it can be assumed that nuclei form within 1 hour compared to bare Cu and uniformly cover the current collector. Lithium continues to deposit on top of the nuclei in the growth regime. In the case of the bare Cu current collector, nuclei continue to form while the existing nuclei grow, suggesting a wide overlap between the nucleation and growth regimes.

[0075] Electrochemical impedance spectroscopy (EIS) measurements showed that the Mo-MG coating had a higher SEI resistance (R SEI ) and charge transfer resistance ( Rct) is clearly shown to have significantly reduced the R of Mo-CC with 10 nm thick Mo-MG deposited during the first cycle. SEI Wow R ct were 29.2 Ω and 58.5 Ω, which were much lower than the bare collector's 127.3 Ω and 255.9 Ω, respectively.

[0076]

[0077] As mentioned above, the Mo-MG coating on the Cu current collector reduced the overpotential, and the overpotential was clearly lowered after the voltage spike, as shown in Fig. 2(c). This is due to the reduction in charge-transfer overpotential, diffusion (in the SEI) overpotential, and / or crystallization overpotential. The reduction in charge-transfer overpotential and diffusion overpotential were estimated through the EIS measurement in Fig. 1(d). The reduction in crystallization overpotential could be another reason for the lower total overpotential by the MG coating. The conversion reaction in the MG, which is an inherent property of metallic glasses, and / or the homogeneity of the MG can reduce the crystallization overpotential. First, it was expected that the MG would transform from a lithium-halophilic to a lithium-philic coating after lithium diffusion into the MG and subsequent lithium deposition. The adsorbate atoms located on the electrode surface from the electrolyte diffuse through the growth phase and eventually reach stable growth sites such as kinks. The Nernst equation mainly depends on the ratio of the concentration (or activity) of adsorbed atoms at the growth site and near the growth site, η. c can be used to estimate η. c The higher the value, the higher the concentration of adsorbate atoms in the surface region far from the growth site. This is interpreted as the slow diffusion rate of adsorbate atoms compared to the reaction rate of adsorbate atoms in the step and kink. As the surface diffusivity decreases, the surface diffusion penetration distance (λ0) becomes shorter. The average current density (i) is a function of the overpotential, the distance between the two incident growth points (2x0), and λ0 under steady-state conditions.

[0078] (Formula 1)

[0079]

[0080] (Formula 2)

[0081]

[0082] Here,

[0083]

[0084] In Equations 1 and 2, i0, α, z, F, R, T, D, and c are the exchange current density, charge transfer coefficient, charge transfer valence, Faraday constant, gas constant, temperature, surface diffusivity, and equilibrium concentration of adsorbed atoms (when η = 0), respectively. Since the overpotential in Fig. 2(a) was measured under a constant current, it can be assumed that the overpotential was measured under steady-state conditions. Equation 1 (λ0 / x0>>1) indicates a pure charge transfer current density, i.e., one that does not interfere with crystallization. In contrast, Equation 2 (λ0 / x0<<1)) represents the relationship between the current and the pure crystallization overpotential. In this case, the effective charge transfer coefficient in Equation 2 is reduced to half of that in Equation 1 by multiplying the exponent term of λ0 by η. According to Equations 1 and 2, when the crystallization overpotential becomes dominant, the importance of λ0 / x0 in the equation increases. As λ0 / x0 increases, η in Equation 2 under constant current conditions cis reduced. According to Equation 2, the lower growth overpotential for Mo-CC compared to bare Cu in Fig. 2(c) means that the diffusivity of adsorbate atoms for Mo-CC is high (larger λ0) and the distance between adjacent nuclei is shorter (smaller x0). Since lower overpotential leads to fewer nuclei, smaller x0 can be achieved by forming 2D-shaped nuclei. 2D-shaped nuclei are known to form on the surface without defects such as dislocations and grain boundaries. As λ0 / x0 increases, the current density also decreases because the adsorbate atoms are distributed more uniformly. Therefore, the Mo-MG coating helps form 2D-shaped nuclei, increases surface diffusivity, and prevents dendrite formation by reducing the local current density.

[0085] It can be clearly seen from Equation 2 above that the decrease in crystallization overpotential is due to the uniformity of the Mo-MG thin film. This is supported by the result that the crystallization of Mo-MG leads to a decrease in the Coulombic efficiency.

[0086] Uniformly coating MG on the current collector is a novel approach to achieving superior electrochemical performance in gold-free lithium metal batteries, as the amorphous structure of the battery provides uniform nucleation sites, which are further enhanced by lithium absorption. Furthermore, the electrical conductivity of MG is beneficial for reducing series resistance. To our knowledge, the use of metallic glasses as active electrode materials in lithium-ion batteries has been reported, but the application of metallic glass thin films as seed layers on current collectors has not been investigated.

[0087] Referring to FIG. 1(e) and FIG. 3(d), in a symmetric cell having a pair of lithium metal negative electrodes coated with MG facing each other and including an electrolyte and a separator between them, the electrolyte is a mixture of DOL / DME 1M LiTFSl and 2 wt% LiNO3, and has a capacity of 1.0 mAh / cm 2Capacity and charge / discharge rate were such that a short circuit occurred at 200 cycles in a full cell at 1.0C for bare lithium. However, the lithium metal anode with 10 nm Mo-MG deposited and the symmetric cell and the lithium metal anode with Ti-based metallic glass deposited showed stable and low voltage.

[0088]

[0089] The present invention is not limited to the above-described embodiments, but can be manufactured in a variety of different forms. Those skilled in the art will appreciate that the present invention can be implemented in other specific forms without altering the technical spirit or essential characteristics of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive.

Claims

1. A positive electrode; a negative electrode current collector facing the positive electrode and made of copper foil; an electrolyte positioned between the positive electrode and the negative electrode current collector; and a separator separating the positive electrode and the negative electrode current collector; wherein the interface where the current collector comes into contact with the electrolyte is made of metallic glass. A non-anode lithium secondary battery characterized by being coated.

2. A lithium metal secondary battery comprising: a positive electrode; a lithium metal negative electrode positioned facing the positive electrode; an electrolyte positioned between the positive electrode and the lithium metal negative electrode; and a separator separating the positive electrode and the lithium metal negative electrode; wherein the surface of the lithium metal negative electrode is coated with metallic glass.

3. A lithium secondary battery comprising: a positive electrode; a lithium metal negative electrode positioned facing the positive electrode; a negative electrode current collector made of copper foil positioned in contact with the lithium metal negative electrode and facing the positive electrode; an electrolyte positioned between the positive electrode and the lithium metal negative electrode; and a separator separating the positive electrode and the lithium metal negative electrode; wherein the surface of the lithium metal negative electrode is coated with metallic glass.

4. An all-solid-state secondary battery comprising: a positive electrode; a negative electrode positioned facing the positive electrode; and a solid electrolyte filled between the positive electrode and the negative electrode; characterized in that an interfacial layer of a metal glass layer is formed between the solid electrolyte and the negative electrode.

5. A secondary battery comprising a metal glass film formed between an electrolyte and a negative electrode collector, between an electrolyte and a lithium metal negative electrode, or between an electrolyte and a separator, wherein the electrolyte uses a liquid electrolyte.

6. A secondary battery comprising a metal glass film formed between an electrolyte and a negative electrode current collector or between an electrolyte and a lithium metal negative electrode, wherein the electrolyte uses a solid electrolyte.

7. In any one of claims 1 to 6, A non-anode lithium secondary battery using a metallic glass and a metallic glass thin film, characterized in that part or all of the metallic glass and the metallic glass thin film are crystallized during charging and discharging.

8. In any one of claims 1 to 6, The above metallic glass contains at least two different elements, The above metal glass is a secondary battery containing a component represented by the following formula 1. (Am1) n1 + (Am2) n2 + (Am3) n3 + ····· + (Amx) ny (Formula 1) (In the above formula 1, Am1, Am2, Am3, ····· , Amx represent different metallic glass elements, x is an integer greater than or equal to 2, and satisfies n1 > 0, n2 > 0, n3 ≥ 0, ····· , ny ≥ 0 and n1 + n2 + ····· + ny = 100) 9. In claim 8, The above metallic glass is a secondary battery that satisfies the enthalpy relationship of Equation 2 below. △H total = △H 12 + △H 13 + △H 14 + ····· + △H 1x + △H 23 + △H 24 + ····· + △H 2x + △H 34 + ····· + △H 3x + ····· + △H (x-1)x < 0 (Equation 2) (In the above equation 2, △H (x-1)x represents a mixed series of elements Am(x-1) and Am(x)) 10. In claim 9, The above metallic glass is composed of lanthanum (La), cerium (Ce), praseodymium (Pr), promethium (Pm), samarium (Sm), lutetium (Lu), yttrium (Y), neodymium (Nd), gadolinium (Gd), terbium (Tb), dysprosium (Dy), hormium (Ho), erbium (Er), thulium (Tm), thorium (Th), calcium (Ca), scandium (Sc), barium (Ba), beryllium (Be), bismuth (Bi), rubidium (Rb), germanium (Ge), lead (Pb), ytterbium (Yb), chromium (Cr), strontium (Sr), europium (Eu), zirconium (Zr), thallium (Tl), lithium (Li), hafnium (Hf), magnesium (Mg), phosphorus (P), arsenic (As), iron (Fe), A secondary battery comprising a mixture of two or more elements selected from palladium (Pd), gold (Au), plutonium (Pu), cobalt (Co), gallium (Ga), tungsten (W), germanium (Ge), silver (Ag), sodium (Na), molybdenum (Mo), nickel (Ni), aluminum (Al), copper (Cu), zinc (Zn), antimony (Sb), silicon (Si), tin (Sn), titanium (Ti), cadmium (Cd), indium (In), platinum (Pt), and mercury (Hg).

11. In claim 10, A secondary battery comprising the metallic glass of any one of Zr-Al-Ni, Zr-Al-Cu-Ni, Zr-Al-Cu-Ni-Ti, Zr-Be-Cu-Ni-Ti, Mo-Zr-Ti-Si, Mo-Zr-Co-Si, and Ti-Cu-Ni-Zr metallic glasses.

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