Lithium secondary battery

Abstract

The present disclosure relates to a lithium secondary battery. According to an embodiment of the present disclosure for solving technical problems, a lithium secondary battery comprises a negative electrode, a positive electrode, a separator disposed between the negative electrode and the positive electrode, and a first electrolyte in contact with the negative electrode and the separator, wherein the first electrolyte may contain a zeolite powder.

Description

lithium secondary battery

[0001] The present disclosure relates to a lithium secondary battery.

[0002] Recently, accompanied by the rapid proliferation of battery-powered electronic devices such as mobile phones, laptop computers, and electric vehicles, the demand for high-energy-density, high-capacity rechargeable batteries is rapidly increasing. Accordingly, research and development to improve the performance of lithium-ion batteries is actively underway.

[0003] A lithium secondary battery is a battery comprising a positive electrode and a negative electrode containing an active material capable of lithium ion intercalation and deintercalation, and an electrolyte, and produces electrical energy through oxidation and reduction reactions when lithium ions are intercalated / deintercalated from the positive electrode and the negative electrode.

[0004] Lithium-ion rechargeable batteries face limitations in applying the latest technologies currently under development. For example, electric vehicles can only travel about 400 km on a single charge, and smartphones struggle to last more than 24 hours on a single charge. This is due to the limited energy density of lithium-ion rechargeable batteries. The most direct way to improve this is to reduce the weight or volume of the battery; removing the negative electrode active material layer, which accounts for a large proportion of the battery weight, such as graphite or silicon, or replacing it with lithium metal, can significantly contribute to increasing the battery's energy density. However, in this case, lithium precipitated on the negative electrode current collector consumes the electrolyte and forms lithium dendrites, posing significant constraints in terms of lifespan and safety. In particular, if the highly flammable electrolytes used conventionally are utilized, side reactions with the highly reactive lithium metal may occur vigorously, potentially leading to safety issues.

[0005] Side reactions between lithium metal and electrolytes and dendrite growth lead to safety issues in lithium metal batteries, so it may be necessary to develop lithium metal batteries that can fundamentally solve these problems.

[0006] The information described above disclosed in the background technology of this invention is intended only to enhance understanding of the background of the present invention and may therefore include information that does not constitute prior art.

[0007] The problem that the present invention aims to solve is to provide a lithium secondary battery for solving the above-mentioned problems.

[0008] However, the technical problems that the present invention aims to solve are not limited to those described above, and other unmentioned problems can be clearly understood by those skilled in the art from the description of the invention below.

[0009] According to some embodiments of the present disclosure for solving the above technical problem, a lithium secondary battery comprises a negative electrode, a positive electrode, a separator disposed between the negative electrode and the positive electrode, and a first electrolyte in contact with the negative electrode and the separator, and the first electrolyte may comprise zeolite powder.

[0010] According to some embodiments of the present disclosure for solving the above technical problem, a lithium secondary battery comprises a negative electrode, a positive electrode, a separator disposed between the negative electrode and the positive electrode, a composite polymer electrolyte in contact with the negative electrode and the separator, and a gel polymer electrolyte in contact with the positive electrode, wherein the composite polymer electrolyte comprises zeolite powder, and the gel polymer electrolyte may comprise a liquid electrolyte and a cross-linked polymer.

[0011] According to some embodiments of the present disclosure, a first electrolyte comprising zeolite powder can improve ion conductivity by providing a pathway for the movement of lithium ions. Additionally, the zeolite powder can increase the stability of the secondary battery and improve the performance and lifespan of the battery by suppressing thermal shrinkage of the separator occurring inside the secondary battery. With this configuration, lithium ions are homogenized to improve the lithium ion flux, thereby allowing lithium ions to be uniformly electrodeposited on the negative electrode current collector.

[0012] According to some embodiments of the present disclosure, by coating a ceramic on one surface of a separator, thermal shrinkage of the separator can be prevented, thereby increasing the stability of the lithium secondary battery.

[0013] By using the first electrolyte and the second electrolyte according to some embodiments of the present disclosure, a lithium secondary battery with improved initial efficiency characteristics and lifespan characteristics can be manufactured.

[0014] However, the effects obtainable through the present invention are not limited to those described above, and other unmentioned technical effects will be clearly understood by those skilled in the art from the description of the invention below.

[0015] The following drawings attached to this specification illustrate preferred embodiments of the present invention and serve to further enhance understanding of the technical concept of the present invention together with the detailed description of the invention provided below; therefore, the present invention should not be interpreted as being limited only to the matters described in such drawings.

[0016] FIG. 1 is a diagram showing a stacked structure of a lithium secondary battery including a first electrolyte according to one embodiment.

[0017] Figure 2 is a diagram showing the stacked structure of the lithium secondary battery of Figure 1 after charging.

[0018] FIG. 3 is a diagram showing a stacked structure of a lithium secondary battery including a first electrolyte according to one embodiment.

[0019] Figure 4 is a diagram showing the stacked structure of a lithium secondary battery including a first electrolyte and a second electrolyte.

[0020] Figure 5 is a diagram showing the stacked structure of a lithium secondary battery with ceramic coated on the separator.

[0021] FIG. 6 is a perspective view illustrating a lithium secondary battery according to one embodiment.

[0022] FIG. 7 is a perspective view illustrating a lithium secondary battery according to one embodiment.

[0023] FIG. 8 is a perspective view illustrating a lithium secondary battery according to one embodiment.

[0024] FIG. 9 is a perspective view illustrating a lithium secondary battery according to one embodiment.

[0025] Hereinafter, embodiments of the present invention will be described in detail. However, these are presented as examples and are not intended to limit the present invention, and the present invention is defined only by the scope of the claims set forth below.

[0026] Unless otherwise specifically stated in this specification, when a part such as a layer, film, region, plate, etc. is described as being "on" another part, this includes not only cases where it is "immediately on" another part, but also cases where there is another part in between.

[0027] Unless otherwise specified in this specification, a singular form may also include a plural form. Additionally, unless otherwise specified, "A or B" may mean "including A, including B, or including A and B."

[0028] In this specification, "combination of these" may mean a mixture of components, a laminate, a composite, a copolymer, an alloy, a blend, and a reaction product, etc.

[0029] Methods and materials similar or equivalent to those described herein may be used in the practice or testing of the present invention, but suitable methods and materials are described herein. The singular expression includes the plural expression unless the context clearly indicates otherwise.

[0030] In this specification, terms such as “comprising” or “having” are intended to indicate the existence of the features, numbers, steps, actions, components, parts, components, materials, or combinations thereof described in the specification, and should be understood as not excluding in advance the existence or addition of one or more other features, numbers, steps, actions, components, parts, components, materials, or combinations thereof.

[0031] In this specification, the term “and / or” means any combination of one or more items described in relation and all combinations thereof. In this specification, the term “or” means “and / or”.

[0032] In this specification, when a part such as a layer, film, region, plate, etc. is described as being "on" another part, this includes not only cases where it is directly above the other part, but also cases where there is another part in between.

[0033] In this specification, terms such as "first," "second," etc., may be used to describe various components, but the components should not be limited by these terms. The terms are used solely for the purpose of distinguishing one component from another.

[0034] In this specification, “metal” includes both metals and metalloids such as silicon and germanium in an elemental or ionic state. In this specification, “alloy” means a mixture of two or more metals.

[0035] In this specification, "anode active material" refers to an anode material capable of undergoing lithiation and delithiation. In this specification, "anode active material" refers to an anode material capable of undergoing lithiation and delithiation.

[0036] In this specification, "lithiation" and "to lithiate" refer to the process of adding lithium to a positive electrode active material or a negative electrode active material. In this specification, "delithiation" and "to delithiate" refer to the process of removing lithium from a positive electrode active material or a negative electrode active material.

[0037] In this specification, "charge" and "to charge" refer to the process of providing electrochemical energy to a battery. In this specification, "discharge" and "to discharge" refer to the process of removing electrochemical energy from a battery.

[0038] In this specification, "anode" and "cathode" refer to electrodes where electrochemical reduction and lithiation occur during the discharge process. In this specification, "negative electrode" and "anode" refer to electrodes where electrochemical oxidation and delithiation occur during the discharge process.

[0039] Exemplary embodiments will be described in more detail below.

[0040] For example, among lithium secondary batteries, a negative electrode-free lithium secondary battery is a battery that uses only a negative electrode current collector without a negative electrode active material layer, and the battery can be operated through a process in which lithium ions transferred from the positive electrode are deposited on the surface of the negative electrode current collector during charging, and the lithium deposited on the negative electrode current collector is leached out again and inserted into the positive electrode during discharging.

[0041] Anode-free lithium secondary batteries can have the advantage of maximizing energy density per unit volume and weight of the battery by omitting lithium metal used as the anode active material. However, lithium metal precipitated during operation causes lithium dendrites to grow due to non-uniform current concentration during oxidation and reduction processes, and these lithium dendrites can cause losses in the lithium anode, thereby degrading the battery's capacity and lifespan characteristics. Additionally, the growth of lithium dendrites can cause a short circuit between the anode and the cathode.

[0042] Secondary batteries may utilize ion-conducting electrolytes in which salts are dissolved in organic solvents. However, the electrolyte is prone to degrading electrode materials and volatilizing organic solvents, and safety is low due to combustion caused by rising ambient and / or battery temperatures. Additionally, during charging and discharging, gas is generated inside the battery due to the decomposition of the organic solvent and / or adverse reactions between the solvent and the electrodes, which can cause the battery thickness to expand.

[0043] To improve liquid electrolytes, complex polymer electrolytes (CPEs) can be applied. Complex polymer electrolytes have a structure in which inorganic fillers and a liquid electrolyte are combined within a polymer matrix, and they can exhibit excellent electrochemical stability and mechanical strength. Inorganic fillers can enhance ion conductivity by forming ion conduction pathways within the polymer or by facilitating lithium ion migration.

[0044] In addition, to improve the liquid electrolyte described above, a gel polymer electrolyte (GPE) can be applied. Gel polymer electrolytes have high electrochemical safety and can maintain a constant thickness of the battery. Furthermore, due to the adhesive strength unique to the gel phase, the contact between the electrode and the electrolyte can be excellent.

[0045] In addition, in lithium secondary batteries utilizing lithium metal as the negative electrode active material layer, stable formation of a Solid Electrolyte Interphase (SEI) film can suppress side reactions of the lithium metal, control lithium dendrites, and simultaneously improve high-temperature safety. SEI refers to a solid film formed on the surface of the negative electrode material as a result of a chemical reaction that occurs when materials in the electrolyte undergo electrolysis for the first time during the process of lithium ions moving to the negative electrode during the initial charging of the lithium secondary battery. SEI prevents further decomposition reactions of the electrolyte and enables lithium ions to move through the electrolyte.

[0046] According to the present disclosure, the composite polymer electrolyte may include a cross-linked polymer, a linear polymer, and a zeolite powder. The gel polymer electrolyte may include a cross-linked polymer.

[0047] A gel polymer electrolyte and a composite polymer electrolyte according to one embodiment of the present disclosure are a lithium secondary battery or a positive electrode having a negative electrode capacity per unit area (mAh / cm²) for an anode that is anode-free and has a negative electrode active material layer absent on a negative electrode current collector. 2 It can be applied to lithium metal secondary batteries with a ratio of less than 1.

[0048] FIG. 1 is a drawing showing a stacked structure of a lithium secondary battery (100) including a first electrolyte (160) according to one embodiment. FIG. 2 is a drawing showing a stacked structure of the lithium secondary battery (100) of FIG. 1 after charging. FIG. 3 is a drawing showing a stacked structure of a lithium secondary battery (300) including a first electrolyte (360) according to one embodiment.

[0049] FIG. 1 is a drawing showing a stacked structure of a non-anode lithium secondary battery (100), and FIG. 2 may correspond to a drawing showing lithium metal precipitated on a negative current collector as the non-anode lithium secondary battery (100) is charged. FIG. 3 may correspond to a drawing showing a lithium metal secondary battery (300) in which lithium metal is used as a negative active material layer. The thickness of each layer shown in FIG. 1 to FIG. 3 is shown as an arbitrary size and is not necessarily limited thereto.

[0050] A lithium secondary battery according to one embodiment may include a negative electrode, a separator, and a first electrolyte disposed between the negative electrode and the separator. The first electrolyte may correspond to a composite polymer electrolyte. Although the present disclosure primarily describes a lithium metal secondary battery comprising a composite polymer electrolyte, it is not limited thereto and may be, for example, a lithium primary battery, and may also be applied to lithium-sulfur batteries, lithium-air batteries, etc.

[0051] Referring to FIG. 1, a lithium secondary battery (100) according to one embodiment may include a negative electrode or negative current collector (140), a separator (170), and the first electrolyte (160) described above disposed between the negative electrode or negative current collector (140) and the separator (170).

[0052] A lithium secondary battery (100) according to one embodiment may include a negative electrode current collector (140), a first electrolyte (160) disposed above the negative electrode current collector (140), and a positive electrode (130) disposed above the first electrolyte (160), as shown in FIG. 1. The negative electrode may include a negative electrode current collector (140) in which the negative electrode active material layer is free, and the positive electrode (130) may include a positive electrode current collector (110) and a positive electrode active material layer (120) disposed on the positive electrode current collector (110). The first electrolyte (160) may correspond to a composite polymer electrolyte.

[0053] A lithium secondary battery (300) according to one embodiment may further include a lithium metal layer (350) disposed between a negative electrode current collector (340) and a first electrolyte (360), as shown in FIG. 3. In this case, the negative electrode may include a lithium metal layer (350) disposed between the negative electrode current collector (340) and the first electrolyte (360). For example, the lithium secondary battery (300) may include a negative electrode current collector (340), a lithium metal layer (350) disposed above the negative electrode current collector (340), a first electrolyte (360) disposed above the lithium metal layer (350), a separator (370) disposed above the first electrolyte (360), and a positive electrode (330) disposed above the separator (370). The positive electrode (330) may include a positive electrode current collector (310) and a positive electrode active material layer (320) disposed on the positive electrode current collector (310). Accordingly, a separator (370) may be disposed between the positive electrode active material layer (320) and the first electrolyte (360).

[0054] For example, the lithium metal layer (350) may include lithium metal or a lithium alloy. During the discharge process, the lithium metal layer (350) may dissociate into lithium ions and metal cations, thereby reducing the thickness of the lithium metal layer (350). Conversely, during the charging process, lithium ions may be electrodeposited on the lithium metal layer (350), thereby increasing the thickness of the lithium metal layer (350).

[0055] According to one embodiment, a lithium secondary battery (100, 300) comprising a first electrolyte (160, 360) may further include a protective layer (not shown) disposed between a negative electrode and the first electrolyte (160, 360). For example, the protective layer may be formed between a negative electrode current collector (140) and the first electrolyte (160). Alternatively, the protective layer may be formed between a lithium metal layer (350) and the first electrolyte (360). According to one embodiment, the protective layer of the lithium secondary battery (100, 300) comprises an inorganic oxide, and the first electrolyte (160, 360) may be disposed between the protective layer and the positive electrode (130, 330).

[0056] According to one embodiment, one or more stacked structures of the lithium secondary battery (100, 300) as described above may be stacked or wound and accommodated in a case, and the case may be classified into cylindrical, prismatic, thin film, coin, pin type, etc.

[0057] First electrolyte

[0058] Referring to FIGS. 1 to 3, the first electrolyte (160, 360) according to one embodiment may correspond to a composite polymer electrolyte. For example, the first electrolyte (160, 360) may include zeolite powder. The zeolite powder may be uniformly dispersed within the polymer matrix of the composite polymer electrolyte and may improve the ionic conductivity of the composite polymer electrolyte. For example, the zeolite powder may have a porous structure. This configuration provides a pathway for the movement of lithium ions, thereby improving ionic conductivity. Additionally, the zeolite powder may suppress thermal shrinkage of the separator occurring inside the secondary battery, thereby increasing the stability of the lithium secondary battery and improving the performance and lifespan of the lithium secondary battery. Furthermore, by homogenizing the lithium ions and improving the lithium ion flux (Li flux), the lithium ions may be uniformly electrodeposited on the negative electrode current collector (140, 340).

[0059] According to one embodiment, the content of zeolite powder relative to the total polymer of the first electrolyte (160, 360) may be 20 wt% to 100 wt%. Alternatively, the content of zeolite powder relative to the total polymer of the first electrolyte (160, 360) may be 30 wt% to 90 wt%, 45 wt% to 90 wt%, or 60 wt% to 90 wt%.

[0060] The first electrolyte (160, 360) may further include a cross-linked polymer. The cross-linked polymer may correspond to an acrylic polymer. According to one embodiment, the acrylic polymer may be formed by an acrylate-based and / or methacrylate-based monomer. For example, the acrylic polymer may be formed from PETTA (Pentaerythritol Tetraacrylate), DPHA (dipentaerythritol hexacrylate), TMPTMA (trimethylolpropane trimethacrylate), PETA (Pentaerythritol Triacrylate), DPEPA (Dipentaerythritol Pentaacrylate), DTMPTTA (Dipentaerythritol Tetramethacrylate), ETPTA (Ethoxylated Trimethylolpropane Triacrylate), TMPTA (Trimethylolpropane Triacrylate), TTEGDA (Triethylene Glycol Diacrylate), or any combination thereof.

[0061] However, the monomers are not limited to those described above, and acrylate and / or methacrylate monomers capable of forming acrylic polymers include, specifically, diethylene glycol diacrylate (DEGDA), diethylene glycol dimethacrylate (DEGDMA), triethylene glycol diacrylate (TEGDA), triethylene glycol dimethacrylate (TEGDMA), tetraethylene glycol diacrylate (TTEGDA), glycidyl methacrylate, polyethylene glycol diacrylate (PEGDA), polyethylene glycol dimethacrylate (PEGDMA), polypropylene glycol diacrylate (PPGDA), dipropylene glycol diacrylate (DPGDA), tripropylene glycol diacrylate (TPGDA), dianol diacrylate (DDA), dianol dimethacrylate (DDMA), ethoxylated trimethylolpropane triacrylate (ETPTA), acrylate-functionalized ethylene oxide, and butanediol It may be formed from dimethacrylate, ethoxylated neopentyl glycol diacrylate (NPEOGDA), propoxylated neopentyl glycol diacrylate (NPPOGDA), trimethylolpropane triacrylate (TMPTA), trimethylolpropane trimethacrylate (TMPTMA), pentaerythritol triacrylate (PETA), ethoxylated propoxylated trimethylolpropane triacrylate (TMPEOTA / TMPPOTA), propoxylated glyceryl triacrylate, tris(2-hydroxyethyl)isocyanurate triacrylate (THEICTA), pentaerythritol tetraacrylate (PETTA), dipentaerythritol pentaacrylate (DPEPA), ditrimethylolpropane tetraacrylate (DTMPTTA), or any combination thereof.

[0062] The first electrolyte (160, 360) may further include a linear polymer. For example, the linear polymer may include a polyethylene oxide (PEO)-based polymer or a polyvinylidene fluoride (PVDF)-based polymer or any combination thereof. According to one embodiment, the linear polymer may include polyethylene oxide or a polyvinylidene fluoride-co-hexafluoropropylene copolymer (PVDF-HFP) or any combination thereof. According to one embodiment, the weight ratio of the crosslinked polymer to the linear polymer may be 2:1 to 10:1. Alternatively, the weight ratio of the crosslinked polymer to the linear polymer may be 5:1 to 10:1, 7:3, or 10:1.

[0063] A first electrolyte (160, 360) according to one embodiment of the present disclosure may further include a liquid electrolyte. The liquid electrolyte may be a mixture of a flame-retardant additive, a lithium salt, and an organic solvent. The organic solvent may be selected from organic solvents used in liquid electrolytes. The lithium salt may be selected from lithium salts used in composite polymer electrolytes. A composite polymer electrolyte may be formed by impregnating a cross-linked polymer and a linear polymer into the liquid electrolyte within a lithium secondary battery.

[0064] Lithium salts are dissolved in organic solvents and can act as a source of lithium ions within the battery, enabling the operation of basic lithium secondary batteries. Lithium salts can facilitate the movement of lithium ions between the anode and the cathode. Examples of lithium salts include LiPF6, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiN(SO3C2F5)2, Li(FSO2)2N, lithium bis(fluorosulfonyl)imide (LiFSI), LiC4F9SO3, and LiN(C x F2 x+1 SO2)(C y F 2y+1 It may further include one or more selected from SO2)(x and y are integers from 1 to 20), lithium trifluoromethanesulfonate, lithium tetrafluoroethanesulfonate, and lithium bis(oxalate)borate (LiBOB).

[0065] A lithium salt according to one embodiment may include lithium hexafluorophosphate (LiPF6), lithium difluoro(oxalato)borate (LiDFOB), lithium tetrafluoroborate (LiBF4), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), or any combination thereof.

[0066] According to one embodiment, the lithium salt may be LiPF6 at a concentration of 1M.

[0067] Organic solvents serve as a medium through which ions involved in the electrochemical reaction of a cell can move. Organic solvents may be carbonate-based, ester-based, ether-based, ketone-based, or alcohol-based solvents, aprotic solvents, or a combination thereof.

[0068] Carbonate-based solvents such as dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), methyl ethyl carbonate (MEC), ethylene carbonate (EC), propylene carbonate (PC), and butylene carbonate (BC) may be used.

[0069] Ester-based solvents such as methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methylpropionate, ethylpropionate, decanolide, mevalonolactone, valerolactone, and caprolactone may be used.

[0070] Dibutyl ether, tetraglame, diglame, dimethoxyethane, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, tetrahydrofuran, etc. can be used as ether-based solvents. In a negative electrode lithium secondary battery or a lithium metal battery with lithium metal as the negative electrode active material layer, ether-based solvents with relatively high reduction safety can be used.

[0071] In addition, cyclohexanone and the like may be used as ketone-based solvents. Ethyl alcohol and isopropyl alcohol and the like may be used as alcohol-based solvents, and as aprotic solvents, nitriles such as R-CN (where R is a straight-chain, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms and may include a double bond, an aromatic ring, or an ether group); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane and 1,4-dioxolane; and sulfolanes may be used.

[0072] The above organic solvent can be used alone or as a mixture of two or more types.

[0073] In one embodiment, the organic solvent included in the first electrolyte (160, 360) is a carbonate-based solvent, and the carbonate-based solvent may include ethylene carbonate (EC), diethyl carbonate (DEC), or any combination thereof. For example, the mixing volume ratio of the organic solvent in the first electrolyte may be EC : DEC = 1 : 1.

[0074] According to some embodiments of the present disclosure, by including a first electrolyte (160, 360) a cross-linked polymer, a linear polymer, and a zeolite powder, the lithium secondary battery including the first electrolyte can have improved initial efficiency characteristics and lifespan characteristics.

[0075] Evaluation results of a lithium secondary battery according to the type and composition of the cross-linked polymer, linear polymer, and zeolite powder of the first electrolyte (160, 360) according to some embodiments of the present disclosure will be described later.

[0076] According to one embodiment, the first electrolyte (160, 360) may be present within the separator (170, 370) described later, or at the interface between the separator (170, 370) and the negative electrode. A lithium secondary battery (100, 300) according to one embodiment may further include a separator (170, 370) disposed between the positive electrode (130, 330) and the negative electrode, and the first electrolyte (160, 360) may be disposed between the separator (170, 370) and the negative electrode. According to one embodiment, the first electrolyte (160, 360) may penetrate into the pores inside the negative electrode and the pores inside the separator (170, 370).

[0077] According to one embodiment, the thickness of the separator (170, 370) may be smaller than the thickness of the first electrolyte (160, 360). For example, the ratio of the thickness of the separator (170, 370) to the thickness of the first electrolyte (160, 360) layer may be 1:1.5 to 1:5. According to one embodiment, the thickness of the first electrolyte (160, 360) layer may be 10 μm or more. For example, the sum of the thickness of the separator (170, 370) and the thickness of the first electrolyte (160, 360) layer may be 10 μm or more.

[0078] According to one embodiment, a first electrolyte (160, 360) excluding zeolite powder may be stirred first, and then a first electrolyte (160, 360) with added zeolite powder may be stirred second. Afterward, the first electrolyte (160, 360) may be injected into a secondary battery case into which a separator (170, 370) is inserted, and then a first electrolyte layer may be formed by thermal crosslinking.

[0079] Second electrolyte

[0080] Referring to FIGS. 4 and 5, the lithium secondary battery (400, 500) may further include a second electrolyte (480, 580). The second electrolyte (480, 580) may correspond to a gel polymer electrolyte. The second electrolyte (480, 580) may be included in the lithium secondary battery (400, 500) together with the first electrolyte (460, 560) described above. A separator (470, 570) may be located between the first electrolyte (460, 560) and the second electrolyte (480, 580).

[0081] A second electrolyte (480, 580) according to one embodiment may include a liquid electrolyte and a cross-linked polymer. The cross-linked polymer may include acrylic, imide, and epoxy types, or any combination thereof.

[0082] Crosslinked polymers can form crosslinked structures alone or in combination, and the crosslinked structures can fix the polymer network in three dimensions by forming chemical bonds between polymer structures. This can increase mechanical strength by limiting the mobility of individual chains and prevent decomposition by solvents or heat.

[0083] According to one embodiment, the acrylic polymer may be formed from PETTA (Pentaerythritol Tetraacrylate), DPHA (Dipentaerythritol Hexaacrylate), TMPTMA (Trimethylolpropane Trimethacrylate), PETA (Pentaerythritol Triacrylate), DPEPA (Dipentaerythritol Pentaacrylate), DTMPTTA (Dipentaerythritol Tetramethacrylate), ETPTA (Ethoxylated Trimethylolpropane Triacrylate), TMPTA (Trimethylolpropane Triacrylate), TTEGDA (Triethylene Glycol Diacrylate), or any combination thereof.

[0084] Imide-based polymers may include polymers formed from biphenyltetracarboxyldianiline (BTDA), polyimides, or any combination thereof.

[0085] Epoxy polymers can be formed from bisphenol-A diglycidyl ether, novolac epoxy, or any combination thereof.

[0086] According to one embodiment, the cross-linked polymer may be in the range of 2 wt% to 20 wt% of the total weight of the second electrolyte (480, 580). Alternatively, the cross-linked polymer may be in the range of 4 wt% to 20 wt%, 6 wt% to 20 wt%, 8 wt% to 20 wt%, 10 wt% to 20 wt%, 12 wt% to 20 wt%, 14 wt% to 20 wt%, or 16 wt% to 20 wt% of the total weight of the second electrolyte (480, 580).

[0087] A second electrolyte (480, 580) according to one embodiment of the present disclosure may further include a liquid electrolyte. The liquid electrolyte may correspond to a mixture of a flame-retardant additive, a lithium salt, and an organic solvent. The organic solvent may be selected from organic solvents used in liquid electrolytes. The lithium salt may be selected from lithium salts used in solid polymer electrolytes. A gel polymer electrolyte may be formed by impregnating a cross-linked polymer into the liquid electrolyte within a lithium secondary battery.

[0088] Lithium salts are dissolved in organic solvents and act as a source of lithium ions within the battery, enabling the operation of basic lithium secondary batteries. Additionally, lithium salts can facilitate the movement of lithium ions between the anode and cathode. Examples of lithium salts include LiPF6, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiN(SO3C2F5)2, Li(FSO2)2N, (lithium bis(fluorosulfonyl)imide (LiFSI), LiC4F9SO3, LiN(C x F2 x+1 SO2)(C y F 2y+1 It may further include one or more selected from SO2)(x and y are integers from 1 to 20), lithium trifluoromethanesulfonate, lithium tetrafluoroethanesulfonate, and lithium bis(oxalate)borate (LiBOB).

[0089] A lithium salt according to one embodiment may include lithium hexafluorophosphate (LiPF6), lithium difluoro(oxalato)borate (LiDFOB), lithium tetrafluoroborate (LiBF4), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), or any combination thereof.

[0090] Organic solvents serve as a medium through which ions involved in the electrochemical reaction of a cell can move. Organic solvents may be carbonate-based, ester-based, ether-based, ketone-based, or alcohol-based solvents, aprotic solvents, or a combination thereof.

[0091] Carbonate-based solvents such as dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), methyl ethyl carbonate (MEC), ethylene carbonate (EC), propylene carbonate (PC), and butylene carbonate (BC) may be used.

[0092] Ester-based solvents such as methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methylpropionate, ethylpropionate, decanolide, mevalonolactone, valerolactone, and caprolactone may be used.

[0093] Dibutyl ether, tetraglame, diglame, dimethoxyethane, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, tetrahydrofuran, etc. can be used as ether-based solvents. In a negative electrode lithium secondary battery or a lithium metal battery with lithium metal as the negative electrode active material layer, ether-based solvents with relatively high reduction safety can be used.

[0094] In addition, cyclohexanone and the like may be used as ketone-based solvents. Ethyl alcohol and isopropyl alcohol and the like may be used as alcohol-based solvents, and as aprotic solvents, nitriles such as R-CN (where R is a straight-chain, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms and may include a double bond, an aromatic ring, or an ether group); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane and 1,4-dioxolane; and sulfolanes may be used.

[0095] Each of the above-described organic solvents can be used alone or in a mixture of two or more.

[0096] A second electrolyte (480, 580) according to one embodiment of the present disclosure may further include an initiator. By the initiator, the formation of a cross-linked structure of the gel polymer electrolyte may be induced. For example, the initiator may correspond to tert-butyl peroxypivalate (TBPP). For example, 3 wt% of the initiator may be added to the second electrolyte relative to the total weight of the cross-linked polymer described above.

[0097] According to some embodiments of the present disclosure, a lithium secondary battery (400, 500) comprising a first electrolyte (460, 560) and a second electrolyte (480, 580) may have improved initial efficiency characteristics and lifespan characteristics.

[0098] According to one embodiment, the second electrolyte (480, 580) may be present within the positive electrode (430, 530) or at the interface of the positive electrode (430, 530). A lithium secondary battery (400, 500) according to one embodiment may further include a separator (470, 570) disposed between the positive electrode (430, 530) and the negative electrode (440, 540), and the second electrolyte (480, 580) may be disposed between the separator and the positive electrode (430, 530). According to one embodiment, the second electrolyte (480, 580) may penetrate into the pores inside the positive electrode (430, 530).

[0099] According to one embodiment, the second electrolyte (480, 580) can be formed by injecting the second electrolyte (480, 580) between the positive electrode (430, 530) and the separator (470, 570) of a lithium secondary battery (400, 500) in which the negative electrode (440, 540), the first electrolyte (460, 560), the separator (470, 570), and the positive electrode (430, 530) are sequentially stacked after stirring the above-described liquid electrolyte, crosslinkable polymer, and initiator, and then thermally crosslinking the second electrolyte (480, 580).

[0100] Cathode: Cathode current collector

[0101] Referring to FIGS. 1 and 3, the negative current collector (140, 340) may not include a negative active material layer. In the negative current collector (140, 340) that does not include a negative active material layer, lithium metal may be plated onto the negative current collector by charging. The plated metal layer (150) may include plated lithium, lithium metal foil, lithium metal powder, lithium alloy foil, lithium alloy powder, an organic compound containing lithium, or a combination thereof. The metal layer (150) may include non-fibrous lithium, non-needle lithium, plate lithium, or any combination thereof. The lithium alloy contains lithium and a first metal, and the first metal may include indium (In), silicon (Si), gallium (Ga), tin (Sn), aluminum (Al), titanium (Ti), zirconium (Zr), niobium (Nb), germanium (Ge), antimony (Sb), bismuth (Bi), gold (Au), platinum (Pt), palladium (Pd), magnesium (Mg), silver (Ag), zinc (Zn), nickel, iron, cobalt, chromium, cesium, sodium, potassium, calcium, yttrium, bismuth, tantalum, hafnium, barium, vanadium, strontium, lanthanum, or a combination thereof.

[0102] The material constituting the negative electrode current collector (140, 340) can be any material that does not react with lithium, that is, a material that does not form an alloy or compound with lithium and has conductivity. The metal substrate is, for example, a metal or an alloy. The metal substrate may be made of, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof. The electrode current collector may have a shape selected from, for example, a sheet, foil, film, plate, porous body, mesoporous body, through-hole containing body, polygonal ring body, mesh body, foam, and nonwoven body, but is not necessarily limited to these shapes and any shape used in the relevant technical field is possible.

[0103] The negative current collector (140, 340) includes, for example, a first metal substrate. The first metal substrate includes the first metal as a main component or is made of the first metal. The first metal substrate includes the first metal as a main component or is made of the first metal. The content of the first metal included in the first metal substrate is, for example, 90 weight% or more, 95 weight% or more, 99 weight% or more, or 99.9 weight% or more with respect to the total weight of the first metal substrate. The first metal substrate may be composed of, for example, a material that does not react with lithium, that is, does not form an alloy and / or compound with lithium.

[0104] The first metal may be, for example, copper (Cu), nickel (Ni), stainless steel (SUS), iron (Fe), and cobalt (Co), but is not necessarily limited to these; any metal used as a current collector in the relevant technical field may be used. The first metal substrate may be composed of, for example, one of the metals described above, or may be composed of an alloy of two or more metals. The first metal substrate is, for example, in the form of a sheet or foil.

[0105] The negative current collector (140, 340) may further include a coating layer (not shown) containing a second metal on a first metal substrate.

[0106] The negative current collector (140, 340) may include, for example, a first metal substrate and a coating layer disposed on the first metal substrate and comprising a second metal. The second metal has a higher Mohs hardness than the first metal. That is, since the coating layer comprising the second metal is harder than the substrate comprising the first metal, deterioration of the first metal substrate can be prevented. The Mohs hardness of the material constituting the first metal substrate is, for example, 5.5 or less. The Mohs hardness of the first metal is, for example, 5.5 or less, 5.0 or less, 4.5 or less, 4.0 or less, 3.5 or less, or 3.0 or less. The Mohs hardness of the first metal may be, for example, 2.0 to 6.0. The coating layer comprises the second metal. The coating layer may, for example, comprise the second metal as a main component or be composed of the second metal. The content of the second metal included in the coating layer is, for example, 90% by weight or more, 95% by weight or more, 99% by weight or more, or 99.9% by weight or more with respect to the total weight of the coating layer. The coating layer may be composed of, for example, a material that does not react with lithium, that is, does not form an alloy and / or compound with lithium. The Mohs hardness of the material constituting the coating layer is, for example, 6.0 or more. For example, the Mohs hardness of the second metal is 6.0 or more, 6.5 or more, 7.0 or more, 7.5 or more, 8.0 or more, 8.5 or more, or 9.0 or more. The Mohs hardness of the second metal may be, for example, 6.0 to 12. If the Mohs hardness of the second metal is excessively low, it may be difficult to suppress the deterioration of the negative electrode current collector. If the Mohs hardness of the second metal is excessively high, processing may not be easy. The second metal is one or more selected from, for example, titanium (Ti), manganese (Mn), niobium (Nb), tantalum (Ta), iridium (Ir), vanadium (V), rhenium (Re), osmium (Os), tungsten (W), chromium (Cr), boron (B), ruthenium (Ru), and rhodium (Rh).The coating layer may be composed of, for example, one of the metals described above, or an alloy of two or more metals. The difference in Mohs hardness between the first metal included in the first metal substrate and the second metal included in the coating layer may be, for example, 2 or more, 2.5 or more, 3 or more, 3.5 or more, or 4 or more. By having such a difference in Mohs hardness between the first metal and the second metal, the deterioration of the negative current collector can be suppressed more effectively. The coating layer may have a single-layer structure or a multilayer structure of two or more layers. The coating layer may have a two-layer structure including, for example, a first coating layer and a second coating layer. The coating layer may have a three-layer structure including, for example, a first coating layer, a second coating layer, and a third coating layer. The thickness of the coating layer may be, for example, 10 nm to 1 μm, 50 nm to 500 nm, 50 nm to 200 nm, or 50 nm to 150 nm. The coating layer may be deposited on the first metal substrate by, for example, vacuum deposition, sputtering, plating, etc., but is not necessarily limited to these methods; any method capable of forming a coating layer in the relevant technical field is possible.

[0107] For example, the negative current collector (140, 340) may have a reduced thickness compared to a conventional negative current collector. Accordingly, the negative according to the present disclosure is distinguished from a conventional electrode comprising a thick film current collector by including, for example, a thin film current collector.

[0108] As a result, the energy density of the lithium metal secondary battery employing such electrodes is increased. The thickness of the negative electrode current collector (140, 340) may be, for example, less than 15 μm, 14.5 μm or less, or 14 μm or less. The thickness of the negative electrode current collector (140, 340) may be, for example, 0.1 μm to 15 μm, 1 μm to 14.5 μm, 2 μm to 14 μm, 3 μm to 14 μm, 5 μm to 14 μm, or 10 μm to 14 μm.

[0109] The negative current collector (140, 340) may have a shape selected from, for example, a sheet, a foil, a film, a plate, a porous body, a mesoporous body, a through-hole containing body, a polygonal ring body, a mesh body, a foam, and a nonwoven body, but is not necessarily limited to these shapes and any shape used in the relevant technical field is possible.

[0110] The negative current collector (140, 340) may include, for example, a base film and a metal substrate layer disposed on one or both sides of the base film. The negative current collector may have a structure comprising a substrate, wherein the substrate may include, for example, a base film and a metal substrate layer disposed on one or both sides of the base film. An intermediate layer may be additionally disposed on the metal substrate layer.

[0111] For example, the base film may include, for example, a polymer. The polymer may be, for example, a thermoplastic polymer. The polymer may include, for example, polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polybutylene terephthalate (PBT), polyimide (PI), or a combination thereof. By including a thermoplastic polymer in the base film, the base film may melt upon the occurrence of a short circuit, thereby suppressing a sudden increase in current. The base film may be, for example, an insulator.

[0112] The metal substrate layer may include, for example, copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), or alloys thereof. The metal substrate layer can act as an electrochemical fuse and cut off upon overcurrent to perform a short-circuit prevention function. The limit current and maximum current can be controlled by adjusting the thickness of the metal substrate layer. The metal substrate layer may be plated or deposited on a base film. As the thickness of the metal substrate layer decreases, the limit current and / or maximum current of the negative electrode current collector decreases, thereby improving the stability of the lithium metal secondary battery during a short circuit.

[0113] A lead tab may be added to the metal substrate layer for external connection. The lead tab may be welded to the metal substrate layer or the metal substrate layer / base film laminate by means of ultrasonic welding, laser welding, spot welding, etc. During welding, the base film and / or the metal substrate layer may melt, thereby electrically connecting the metal substrate layer to the lead tab. To make the weld between the metal substrate layer and the lead tab more robust, a metal chip may be added between the metal substrate layer and the lead tab. The metal chip may be a thin sheet of the same material as the metal of the metal substrate layer. The metal chip may be, for example, metal foil, metal mesh, etc. The metal chip may be, for example, aluminum foil, copper foil, SUS foil, etc. The lead tab may be welded to the metal chip / metal substrate layer laminate or the metal chip / metal substrate layer / base film laminate by placing the metal chip on the metal substrate layer and then welding it to the lead tab. During welding, the base film, metal layer, and / or metal chip may melt, allowing the metal layer or the metal layer / metal chip laminate to be electrically connected to the lead tab. A metal chip and / or lead tab may be added to a portion of the metal substrate layer. The thickness of the base film may be, for example, 1 μm to 50 μm, 1.5 μm to 50 μm, 1.5 μm to 40 μm, or 1 μm to 30 μm. By having the base film within this thickness range, the weight of the cathode assembly can be reduced more effectively. The melting point of the base film may be, for example, 100° to 300° (Celsius), 100° to 250° (Celsius) or lower, or 100° to 200° (Celsius). By having the base film within this melting point range, the base film can melt during the welding process of the lead tab and be easily bonded to the lead tab. To improve the adhesion between the base film and the metal substrate layer, a surface treatment such as corona treatment may be performed on the base film.The thickness of the metal substrate layer may be, for example, 0.01 μm to 3 μm, 0.1 μm to 3 μm, 0.1 μm to 2 μm, or 0.1 μm to 1 μm. By having the metal substrate layer within this range of thickness, the stability of the cathode can be ensured while maintaining conductivity. The thickness of the metal piece may be, for example, 2 μm to 10 μm, 2 μm to 7 μm, or 4 μm to 6 μm. By having the metal piece within this range of thickness, the connection between the metal layer and the lead tab can be performed more easily. By having the cathode current collector (140, 340) having this structure, the weight of the electrode can be reduced and, consequently, the energy density can be improved.

[0114] According to one embodiment, a negative active material layer may be free on the negative current collector (140) before charging and discharging. For example, a lithium metal layer may be free on the negative current collector (140, 340) before charging and discharging.

[0115] According to one embodiment, a lithium metal layer (350) including a plate-shaped lithium metal thin film may be disposed on a negative electrode current collector (340) before performing charging and discharging.

[0116] According to one embodiment, the cathode may further include an interlayer disposed between the cathode current collector (140, 340) and the lithium metal layer (150, 350).

[0117] According to one embodiment, the interlayer may be placed directly on one or both sides of, for example, the negative current collector (140, 340). Thus, no other layer may be placed between the negative current collector (140, 340) and the interlayer. By placing the interlayer directly on one or both sides of the negative current collector (140, 340), the bonding strength between the negative current collector (140, 340) and the lithium metal layer (150, 350) may be further improved.

[0118] The thickness of the intermediate layer (not shown) may be, for example, 30% or less of the thickness of the negative current collector (140, 340). The thickness of the intermediate layer (not shown) is, for example, 0.01% to 30%, 0.1% to 30%, 0.5% to 30%, 1% to 25%, 1% to 20%, 1% to 15%, 1% to 10%, 1% to 5%, or 1% to 3% of the thickness of the negative current collector (140, 340). The thickness of the intermediate layer is, for example, 10 nm to 5 µm, 50 nm to 5 µm, 200 nm to 4 µm, 500 nm to 3 µm, 500 nm to 2 µm, 500 nm to 1.5 µm, or 700 nm to 1.3 µm.

[0119] By having the intermediate layer have a thickness within this range, the bonding strength between the negative current collector (140, 340) and the lithium metal layer (150, 350) is further improved, and the increase in interfacial resistance can be suppressed.

[0120] For example, the intermediate layer may include a binder. By including a binder in the intermediate layer, the bonding strength between the negative current collector (140, 340) and the lithium metal layer (150, 350) can be further improved. The binder included in the intermediate layer is, for example, a conductive binder or a non-conductive binder.

[0121] Conductive binders are, for example, ion-conducting binders and / or electronic-conducting binders. Binders that possess both ion conductivity and electronic conductivity may belong to both ion-conducting binders and electronic-conducting binders.

[0122] Ion-conducting binders are, for example, polystyrene sulfonate (PSS), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), poly(methylmethacrylate) (PMMA), polyethylene oxide (PEO), polyethylene glycol (PEG), polyacrylonitrile (PAN), polytetrafluoroethylene (PTFE), polyethylenedioxythiophene (PEDOT), polypyrrole (PPY), polyacrylonitrile (PAN), polyaniline, and polyacetylene. Ion-conducting binders may include polar functional groups. Ion-conducting binders containing polar functional groups are, for example, Nafion, Aquivion, Flemion, Gore, Aciplex, Morgane ADP, sulfonated poly(ether ether ketone) (SPEEK), sulfonated poly(arylene ether ketone ketone sulfone) (SPAEKKS), sulfonated poly(aryl ether ketone) (SPAEK), poly[bis(benzimidazobenzisoquinolinones)] (SPBIBI), poly(styrene sulfonate) (PSS), lithium 9,10-diphenylanthracene-2-sulfonate, DPASLi+ etc.The electronically conductive binder is, for example, polyacetylene, polythiophene, polypyrrole, poly(p-phenylene), poly(phenylenevinylene), poly(phenylenesulfide), polyaniline, etc. The intermediate layer may be, for example, a conductive layer containing a conductive polymer.

[0123] The binder included in the intermediate layer may be, for example, a fluorine-based binder. The fluorine-based binder included in the intermediate layer may be, for example, polyvinylidene fluoride (PVDF). The intermediate layer may be disposed on the negative current collector (140, 340) in a dry or wet manner, for example. The intermediate layer may be, for example, a binding layer including a binder.

[0124] The intermediate layer may additionally include, for example, a carbon-based conductive material. By including the carbon-based conductive material, the intermediate layer may be, for example, a conductive layer. The intermediate layer may be, for example, a conductive layer including a binder and a carbon-based conductive material.

[0125] The intermediate layer may be disposed on the cathode current collector in a dry manner by deposition, for example, CVD, PVD, etc. The intermediate layer may be disposed on the cathode current collector (140, 340) in a wet manner by, for example, spin coating, dip coating, etc. The intermediate layer may be disposed on the cathode current collector (140, 340) by, for example, depositing a carbon-based conductive material on the cathode current collector (140, 340) by deposition. The dry-coated intermediate layer may be composed of a carbon-based conductive material and may not contain a binder. Alternatively, the intermediate layer may be disposed on the cathode current collector (140, 340) by, for example, coating a composition comprising a carbon-based conductive material, a binder, and a solvent on the surface of the cathode current collector (140, 340) and drying it. The intermediate layer may have a single-layer structure or a multi-layer structure including multiple layers.

[0126] Cathode: Lithium metal layer

[0127] Referring to FIG. 3, the lithium secondary battery (300) may further include a lithium metal layer (350) disposed between a negative electrode current collector (340) and a first electrolyte (360). For example, the lithium metal layer (350) may include lithium metal or a lithium alloy. For example, the lithium metal layer (350) may be a negative electrode active material layer. For example, the lithium metal layer (350) may be a lithium electrodeposited layer.

[0128] For example, the lithium metal layer (350) can be formed by electrodepositing lithium ions contained in the first electrolyte (360) onto the negative current collector (340) as the lithium secondary battery is charged. For example, the lithium metal layer (350) may include a lithium alloy and a lithium metal. For example, the lithium alloy included in the lithium metal layer (350) weakens the reactivity of the lithium metal, thereby effectively preventing side reactions between the lithium metal layer (350) and the first electrolyte (360). Additionally, the lithium metal layer (350) has excellent electrical conductivity, which can reduce the internal resistance of the lithium secondary battery (300) containing it. Accordingly, the lithium secondary battery (300) containing the lithium metal layer (350) can have improved lifespan characteristics as well as charge / discharge efficiency.

[0129] According to one embodiment, the lithium metal layer (350) may include, for example, lithium foil, lithium powder, plated lithium, a carbon-based material, or a combination thereof. For example, the lithium metal layer (350) may include lithium foil. In this case, the lithium metal layer (350) may be a negative electrode active material layer. For example, the lithium metal layer (350) may be introduced by coating a slurry containing lithium powder and a binder, etc., onto a negative electrode current collector. For example, the binder may be a fluorine-based binder such as polyvinylidene fluoride (PVDF).

[0130] According to one embodiment, the lithium metal layer (350) may comprise only electrodeposited lithium metal or lithium alloy. In this case, the lithium metal layer (350) may be a lithium electrodeposited layer.

[0131] According to one embodiment, the lithium metal layer (350) may not include a carbon-based negative electrode active material. Accordingly, the lithium metal layer (350) may be made of a metal-based negative electrode active material.

[0132] For example, the thickness of the lithium metal layer (350) may be, for example, 0.1 μm to 100 μm, 0.1 μm to 80 μm, 1 μm to 80 μm, or 10 μm to 80 μm, but is not necessarily limited to these ranges and can be adjusted according to the required shape, capacity, etc. of the lithium secondary battery. If the thickness of the lithium metal layer (350) increases excessively, the structural stability of the lithium secondary battery may decrease and side reactions may increase. If the thickness of the lithium metal layer (350) is excessively small, the energy density of the lithium metal secondary battery (300) may decrease.

[0133] According to one embodiment, the thickness of the lithium foil included in the lithium metal layer (350) may be, for example, 1 μm to 50 μm, 1 μm to 30 μm, or 10 μm to 30 μm, or 10 μm to 80 μm. By having the lithium foil have a thickness within this range, the lifespan characteristics of the lithium metal secondary battery (300) can be further improved.

[0134] According to one embodiment, the particle size of the lithium powder included in the lithium metal layer (350) may be, for example, 0.1 μm to 3 μm, 0.1 μm to 2 μm, or 0.1 μm to 1 μm. By having the lithium powder have a thickness within this range, the lifespan characteristics of the lithium secondary battery (300) can be further improved.

[0135] anode

[0136] Referring to FIGS. 1 to 3, a positive active material layer (120, 320) is disposed on a positive current collector (110, 310) to form a positive electrode (130, 330). A positive active material layer (120, 320) may be disposed on a first electrolyte (160, 360), and a positive current collector (110, 310) may be disposed on the positive active material layer (120, 320).

[0137] Positive: Positive current collector

[0138] Referring to FIGS. 1 to 3, a positive active material layer (120, 320) may be disposed on a positive current collector (110, 310) to form a positive electrode (130, 330). In one embodiment, a positive active material layer (120, 320) may be disposed on a gel polymer electrolyte (160, 360), and a positive current collector (110, 310) may be disposed on the positive active material layer (120, 320).

[0139] The positive electrode (130, 330) includes a positive electrode current collector (110, 310). For example, the positive electrode (130, 330) can be prepared by forming a positive electrode active material layer (120, 320) on the positive electrode current collector (110, 310).

[0140] For example, the positive current collector (110, 310) may include indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof.

[0141] According to one embodiment, the positive current collector (110, 310) may include aluminum (Al). According to one embodiment, the positive current collector (110, 310) may include a base film and a metal layer disposed on one or both sides of the base film, in the same way as the negative current collector (140, 340) described above.

[0142] Anode: Anode active material layer

[0143] The positive active material layer (120, 320) may include a positive active material, a conductive material, and a binder.

[0144] As a positive electrode active material, a compound capable of reversible intercalation and deintercalation of lithium (a lithated intercalation compound) may be used. Specifically, one or more composite oxides of lithium and a metal selected from cobalt, manganese, nickel, and combinations thereof may be used. The composite oxide may be a lithium transition metal composite oxide. Examples include lithium nickel-based oxides, lithium cobalt-based oxides, lithium manganese-based oxides, lithium iron phosphate-based compounds, cobalt-free nickel-manganese-based oxides, or combinations thereof.

[0145] As an example, a compound represented by any one of the following chemical formulas may be used. Li a A 1-b X b O 2-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05), Li a Mn 2-b X b O 4-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05), Li a Ni 1-b-c Co b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2), Li a Ni 1-b-c Mn b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2), Li a Ni b Co c L 1 d G e O2(0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0≤e≤0.1), Li a NiG b O2(0.90≤a≤1.8, 0.001≤b≤0.1), Lia CoG b O2(0.90≤a≤1.8, 0.001≤b≤0.1), Li a Mn 1-b G b O2(0.90≤a≤1.8, 0.001≤b≤0.1), Li a Mn2GbO4(0.90≤a≤1.8, 0.001≤b≤0.1), Li a Mn 1-g G g PO4(0.90≤a≤1.8, 0≤g≤0.5), Li (3-f) Fe2(PO4)3(0≤f≤2), Li a FePO4(0.90≤a≤1.8).

[0146] In the chemical formula, A is Ni, Co, Mn, or a combination thereof; X is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; D is O, F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; and L 1 is Mn, Al, or a combination thereof.

[0147] For example, the cathode active material may be a high-nickel cathode active material in which the nickel content relative to 100 mol% of the metal excluding lithium in a lithium transition metal composite oxide is 80 mol% or more, 85 mol% or more, 90 mol% or more, 91 mol% or more, or 94 mol% or more and 99 mol% or less. The high-nickel cathode active material can achieve high capacity and can be applied to high-capacity, high-density lithium secondary batteries.

[0148] For example, the lithium transition metal oxide may be a compound represented by the following chemical formula 5.

[0149] <Chemical Formula 1>

[0150] Li a Ni x Co y M z O 2-b A b

[0151] In Chemical Formula 1, 1.0≤a≤1.2, 0≤b≤0.2, 0.6≤x<1, 0≤y≤0.3, 0 <z≤0.3, x+y+z=1이고, M은 망간(Mn), 바나듐(V), 마그네슘(Mg), 갈륨(Ga), 규소(Si), 텅스텐(W), 몰리브덴(Mo), 철(Fe), 크롬(Cr), 구리(Cu), 아연(Zn), 티타늄(Ti), 알루미늄(Al) 및 보론(B)으로 이루어진 군으로부터 선택된 하나 이상이고, A는 F, S, Cl, Br 또는 이들의 조합이다.

[0152] In Chemical Formula 1, for example, 0.7≤x<1, 0 <y≤0.3, 0<z≤0.3, 0.8≤x<1, 0<y≤0.3, 0<z≤0.3, 0.8≤x<1, 0<y≤0.2, 0<z≤0.2, 0.83≤x<0.97, 0<y≤0.15, 0<z≤0.15, 또는 0.85≤x<0.95, 0<y≤0.1, 0<z≤0.1일 수 있다.

[0153] For example, the lithium transition metal oxide may be at least one of the compounds represented by the following chemical formulas 1-1 and 1-2.

[0154] <Chemical Formula 1-1>

[0155] LiNi x Co y Mn z O2

[0156] In Chemical Formula 1-1, 0.6≤x≤0.95, 0 <y≤0.2, 0<z≤0.1이다. 예를 들어, 0.7≤x≤0.95, 0<y≤0.3, 0<z≤0.3이다.

[0157] <Chemical Formula 1-2>

[0158] LiNi x Co y Al z O2

[0159] In Chemical Formula 1-2, 0.6≤x≤0.95, 0 <y≤0.2, 0<z≤0.1이다. 예를 들어, 0.7≤x≤0.95, 0<y≤0.3, 0<z≤0.3이다. 예를 들어, 0.8≤x≤0.95, 0<y≤0.3, 0<z≤0.3이다. 예를 들어, 0.82≤x≤0.95, 0<y≤0.15, 0<z≤0.15이다. 예를 들어, 0.85≤x≤0.95, 0<y≤0.1, 0<z≤0.1이다.

[0160] For example, lithium transition metal oxides are LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.88 Co 0.08 Mn 0.04O2 , LiNi 0.8 Co 0.15 Mn 0.05O2 , LiNi 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.88 Co 0.1 Mn 0.02O2 , LiNi 0.8 Co 0.15 Al 0.05O2 , LiNi 0.8 Co 0.1 Mn 0.2O2 or LiNi 0.88 Co 0.1 Al 0.02O2 It could be.

[0161] For example, the positive electrode active material may be one having a coating layer on the surface of a lithium transition metal oxide, or a mixture of a lithium transition metal oxide and a lithium transition metal oxide having a coating layer may be used.

[0162] For example, the coating layer may include a coating element compound of an oxide, hydroxide, oxyhydroxide, oxycarbonate, or hydroxycarbonate of a coating element.

[0163] For example, the compound forming the coating layer may be amorphous or crystalline. The coating elements included in the coating layer may include Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or mixtures thereof. For the coating layer formation process, any coating method may be used as long as the coating can be applied to the lithium transition metal oxide using the coating elements in a manner that does not adversely affect the physical properties of the cathode active material (e.g., spray coating, immersion method, etc.).

[0164] For example, the anode may additionally include an additive that can serve as a sacrificial anode.

[0165] The content of the positive active material is 90% to 99.5% by weight with respect to 100% by weight of the positive active material layer (120, 320), and the content of the binder and the conductive material may each be 0.5% to 5% by weight with respect to 100% by weight of the positive active material layer (120, 320).

[0166] A binder can serve to effectively bond the positive active material particles to each other and also to effectively bond the positive active material to the current collector. Representative examples of binders include, but are not limited to, polyvinyl alcohol, carboxymethylcellulose, hydroxypropylcellulose, diacetylcellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride (PVDF), polyethylene, polypropylene, styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, epoxy resin, (meth)acrylic resin, polyester resin, nylon, etc.

[0167] A conductive material is used to impart conductivity to an electrode, and any electronically conductive material that does not cause chemical changes can be used in the battery being constructed. Examples of conductive materials include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber, carbon nanofiber, and carbon nanotube; metal-based materials in the form of metal powder or metal fibers containing copper, nickel, aluminum, silver, etc.; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0168] separator

[0169] Referring to FIG. 5, a lithium secondary battery (500) according to one embodiment may include a separator (570).

[0170] As the separator (570), polyethylene, polypropylene, polyvinylidene fluoride, or a multilayer film of two or more layers thereof may be used, and of course, a mixed multilayer film such as a polyethylene / polypropylene two-layer separator, a polyethylene / polypropylene / polyethylene three-layer separator, or a polypropylene / polyethylene / polypropylene three-layer separator may be used.

[0171] According to one embodiment, the separator (570) may correspond to a polyolefin-based polymer. For example, the separator (570) may include polyethylene (PE) and polypropylene (PP) or any combination thereof.

[0172] The separator (570) may include a porous substrate and an inorganic layer (572) coated with an inorganic material on one or both sides of the porous substrate. For example, the inorganic layer (572) may be formed by coating a ceramic material on one side facing the anode (530) of the separator (570).

[0173] The porous substrate may be a polymer membrane formed from any one of the following: polyolefins such as polyethylene and polypropylene; polyesters such as polyethylene terephthalate and polybutylene terephthalate; polyacetal; polyamide; polyimide; polycarbonate; polyetherketone; polyaryletherketone; polyetherimide; polyamideimide; polybenzimidazole; polyethersulfone; polyphenylene oxide; cyclic olefin copolymer; polyphenylene sulfide; polyethylene naphthalate; glass fiber; Teflon; and polytetrafluoroethylene, or a copolymer or mixture of two or more of these. For example, the separator (570) may have a porous structure made of the above-described polymer, and the porosity of the porous structure may be 50% or more.

[0174] The ceramic may include, but is not limited to, inorganic particles selected from Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, SrTiO3, BaTiO3, Mg(OH)2, boehmite, and combinations thereof. For example, the ceramic may include aluminum oxide (Al2O3), zirconium oxide (ZrO2), silicon dioxide (SiO2), titanium dioxide (TiO2), lithium phosphate (Li3PO4), and lanoleum-lithium-zirconium oxide (Li7La3Zr2O). 12 It may include aluminum lithium oxide (LiAlO2), iron oxide (Fe2O3), chromium trioxide (CrO3), boehmite (AlO(OH)), or any combination thereof.

[0175] According to one embodiment, the thickness of the separator (570) may be 10 μm or less. For example, the thickness of the ceramic-coated separator (570) may be 9 μm. According to one embodiment, the thickness ratio of the separator (570) and the first electrolyte (560) layer may be 1:1.5 to 1:5. According to one embodiment, the sum of the thickness of the separator (570) and the thickness of the first electrolyte (560) layer may be 10 μm or more.

[0176] According to one embodiment, a separator (570) may be positioned between the first electrolyte (560) and the second electrolyte (580). For example, an inorganic layer (572) may be formed on one side of the separator (570) facing the anode (530), and the inorganic layer (572) may come into contact with the second electrolyte (580), and the first electrolyte (560) may come into contact with the other side of the separator (570) and the cathode (540).

[0177] According to one embodiment, after injecting a first electrolyte (560) into a secondary battery (500) into which a separator (570) is inserted, the first electrolyte (560) is formed by thermal crosslinking, so that the first electrolyte (560) can penetrate into the pores inside the separator (570). After that, the case is disassembled, and one side of the separator (570) is spray-coated with ceramic to form an inorganic layer (572). With this configuration, thermal shrinkage of the separator (570) can be prevented, thereby increasing the stability of the lithium secondary battery (500).

[0178] lithium secondary battery

[0179] FIGS. 6 to 9 are schematic diagrams illustrating a lithium secondary battery according to one embodiment, where FIG. 6 is cylindrical, FIG. 7 is prismatic, and FIGS. 8 and 9 are pouch-type batteries. Referring to FIGS. 6 to 9, the lithium secondary battery (1) includes a battery structure (7, electrode assembly) having a separator (4, separator) interposed between a positive electrode (3) and a negative electrode (2), and a case (5) in which the battery structure (7) is housed. The positive electrode (3), the negative electrode (2), and the separator (4) may be impregnated with an electrolyte (not shown). For example, the first electrolyte described above may be disposed between the negative electrode (2) and the separator (4), and the second electrolyte described above may be disposed between the separator (4) and the positive electrode (3) to manufacture the lithium secondary battery (1). According to one embodiment, a ceramic may be coated on one surface of the separator (4) to form an inorganic layer. The composition and content of the first electrolyte, the second electrolyte, and the separator (4) are the same as described above, and redundant descriptions are omitted.

[0180] As shown in FIG. 6, the lithium secondary battery (1) may include an assembly (6, sealing member) that seals the case (5). Additionally, in FIG. 7, the lithium secondary battery (1) may include a positive lead tab (3') and a positive terminal (3"), a negative lead tab (2') and a negative terminal (2"). As shown in FIG. 8 and FIG. 9, the lithium secondary battery (1) may include electrode tabs (70), namely a positive tab (71) and a negative tab (72), which serve as electrical passages for inducing current formed in the battery structure (7) to the outside.

[0181] Referring to FIG. 6, a lithium secondary battery (1) according to one embodiment includes the anode (3), the cathode (2), and the separator (4) described above. The anode (3), the cathode (2), and the separator (4) are wound or folded to form a battery structure (7). The formed battery structure (7) is housed in a case (5). An electrolyte is injected into the case (5) and sealed with a cap assembly (6) to complete the lithium secondary battery (1). The case (5) is cylindrical but is not necessarily limited to this shape and may be, for example, prismatic, thin film, etc.

[0182] Referring to FIG. 7, a lithium secondary battery (1) according to one embodiment includes a positive electrode (3), the aforementioned negative electrode (2), and a separator (4). The positive electrode (3), the negative electrode (2), and the separator (4) are wound, folded, or stacked to form a battery structure (7). The formed battery structure (7) is housed in a case (5). An electrolyte is injected into the case (5), cross-linked, and sealed to complete the lithium secondary battery (1). The case (5) is prismatic, but is not necessarily limited to this shape and may be, for example, cylindrical, thin film, etc. A positive lead tab (3') and a positive terminal (3") are electrically connected to the positive electrode (3). A negative lead tab (2') and a negative terminal (2") are electrically connected to the negative electrode (2).

[0183] Referring to FIG. 8, a lithium secondary battery (1) according to one embodiment includes a positive electrode (3), the aforementioned negative electrode (2), and a separator (4). A separator (4) is disposed between the positive electrode (3) and the negative electrode (2), and the positive electrode (3), the negative electrode (2), and the separator (4) are wound or folded to form a battery structure (7). The formed battery structure (7) is housed in a case (5). It may include an electrode tab (70) that serves as an electrical path for inducing the current formed in the battery structure (7) to the outside. An electrolyte is injected into the case (5) and sealed to complete the lithium secondary battery (1). The case (5) is prismatic but is not necessarily limited to this shape and may be, for example, cylindrical, thin film, etc.

[0184] Referring to FIG. 9, a lithium secondary battery (1) according to one embodiment includes a positive electrode (3), a negative electrode (2) and a separator (4) as described above. An electrolyte as described above, including a separator (4), is disposed between the positive electrode (3) and the negative electrode (2) to form a battery structure. For example, the battery structure (7) is stacked in a bicell structure and then housed in a case (5). It may include a positive electrode tab (71) and a negative electrode tab (72) that serve as electrical pathways for inducing current formed in the battery structure (7) to the outside. The electrolyte is injected into the case (5) and sealed to complete the lithium secondary battery (1). The case (5) is prismatic but is not necessarily limited to this shape and may be, for example, cylindrical, thin film, etc.

[0185] However, the present invention is not limited to this, and the case (5) may be configured in various shapes such as circular or pouch type. For example, the pouch-type lithium secondary battery corresponds to the lithium secondary battery (1) of FIGS. 6 to 9 in which a pouch is used as the case (5). The pouch-type lithium secondary battery includes one or more battery structures (7). A separator (4) is disposed between the positive electrode (3) and the negative electrode (2) to form the battery structure (7). The battery structure (7) is stacked in a bicell structure, then impregnated with an electrolyte, and then housed and sealed in a pouch to complete the pouch-type lithium secondary battery.

[0186] Specifically, the battery structure (7) including the aforementioned positive electrode (3), negative electrode (2), and separator (4) is simply stacked and contained in a pouch, or wound into a jelly roll shape or folded and contained in a pouch. Subsequently, an electrolyte is injected into the pouch and sealed to complete the lithium secondary battery (1).

[0187] The case (5) may be made of metal such as aluminum, aluminum alloy, nickel-plated steel, or a laminate film or plastic that constitutes the pouch.

[0188] Lithium secondary battery (1) has excellent lifespan characteristics and high rate characteristics, so it is used in, for example, electric vehicles (EV). For example, it is used in hybrid vehicles such as plug-in hybrid electric vehicles (PHEV). In addition, it is used in fields where a large amount of power storage is required. For example, it is used in electric bicycles, power tools, etc.

[0189] A plurality of lithium secondary batteries (1) are stacked to form a battery module, and a plurality of battery modules form a battery pack. Such a battery pack can be used in any device requiring high capacity and high output. For example, it can be used in laptops, smartphones, electric vehicles, etc. A battery module includes, for example, a plurality of batteries and a frame that holds them.

[0190] A battery pack includes, for example, a plurality of battery modules and a bus bar connecting them. The battery modules and / or battery pack may further include a cooling device. A plurality of battery packs are controlled by a battery management system. The battery management system includes a battery pack and a battery control device connected to the battery pack.

[0191] This will be explained in more detail through the following examples and comparative examples. However, the examples are for illustrative purposes only and are not limited thereto.

[0192] Example 1: Cathode current collector / First electrolyte (TMPTMA 7 wt% + PEO 3 wt% + LE 90 wt% + Zeolite powder (60 wt% relative to total polymer)) / Ceramic-coated separator / Second electrolyte / Anode

[0193] A 10 μm copper foil was prepared as a negative electrode current collector. Based on a total of 100 wt% of the first electrolyte, 7 wt% of TMPTMA as a crosslinked polymer, 3 wt% of a linear polymer PEO, and 90 wt% of a liquid electrolyte were prepared. Based on the total amount of the liquid electrolyte, LiPF61M was prepared as the lithium salt, and the liquid electrolyte was prepared such that EC and DEC were in a volume ratio of 1:1. In addition, based on the total weight of the polymers in the first electrolyte, the zeolite powder content was prepared at 60 wt%. Subsequently, the first electrolyte excluding the zeolite powder was stirred for 30 minutes, then the zeolite powder was added and stirred for 3 hours. The first electrolyte was injected into a secondary battery case containing a PE-based separator, and then cured by thermal crosslinking. One side of the separator was spray-coated with aluminum oxide (Al2O3).

[0194] The second electrolyte was prepared as a liquid electrolyte with LiPF61M as the lithium salt and EC and DEC in a volume ratio of 1:1, TMPTMA as the crosslinking polymer at 4 wt% based on 100 wt% of the total weight of the second electrolyte, and TBPP (tert-butyl peroxypivalate) as the initiator at 3 wt% based on 100% of the total weight of the crosslinking polymer, and stirred for 3 hours.

[0195] An electrode assembly was prepared by sequentially stacking a cathode, a first electrolyte, a separator, and a positive electrode (e.g., 13.5 μm aluminum foil), and a second electrolyte was injected between the positive electrode and the separator. Then, a lithium secondary battery was prepared by thermal crosslinking.

[0196] Example 2: Cathode current collector / First electrolyte (TMPTMA 7 wt% + PEO 3 wt% + LE 90 wt% + zeolite powder (90 wt% relative to total polymer)) / Ceramic-coated separator / Second electrolyte / Anode

[0197] When preparing the first electrolyte, the zeolite powder content was prepared at 90 wt% based on the total polymer weight of the first electrolyte, and a lithium secondary battery was prepared in the same manner as in Example 1, except for this.

[0198] Example 3: Cathode current collector / First electrolyte (TMPTMA 7 wt% + PEO 3 wt% + LE 90 wt% + zeolite powder (45 wt% relative to total polymer)) / Ceramic-coated separator / Second electrolyte / Anode

[0199] When preparing the first electrolyte, the content of the zeolite powder was prepared at 45 wt% based on the total weight of the polymer of the first electrolyte, and a lithium secondary battery was prepared in the same manner as in Example 1, except for this.

[0200] Example 4: Cathode current collector / First electrolyte (TMPTMA 7 wt% + PEO 3 wt% + LE 90 wt% + zeolite powder (30 wt% relative to total polymer)) / Ceramic-coated separator / Second electrolyte / Anode

[0201] When preparing the first electrolyte, the content of the zeolite powder was prepared at 30 wt% based on the total weight of the polymer of the first electrolyte, and a lithium secondary battery was prepared in the same manner as in Example 1, except for this.

[0202] Example 5: Cathode current collector / First electrolyte (TMPTMA 7 wt% + PVDF-HFP 3 wt% + LE 90 wt% + Zeolite powder (60 wt% relative to total polymer)) / Ceramic-coated separator / Second electrolyte / Anode

[0203] A lithium secondary battery was prepared in the same manner as in Example 1, except that PVDF-HFP was used instead of PEO when preparing the first electrolyte, and the type of linear polymer was different.

[0204] Example 6: Cathode current collector / First electrolyte (TMPTMA 10 wt% + PEO 1 wt% + LE 89 wt% + Zeolite powder (60 wt% relative to total polymer)) / Ceramic-coated separator / Second electrolyte / Anode

[0205] A lithium secondary battery was prepared in the same manner as in Example 1, except that the content of TMPTMA, PEO, and liquid electrolyte (LE) was different when preparing the first electrolyte.

[0206] Comparative Example 1: Cathode current collector / First electrolyte (TMPTMA 7 wt% + PEO 3 wt% + LE 90 wt% / Ceramic-coated separator / Second electrolyte / Anode

[0207] A lithium secondary battery was prepared in the same manner as in Example 1, except that zeolite powder was not added during the preparation of the first electrolyte.

[0208] Comparative Example 2: Cathode current collector / First electrolyte (TMPTMA 7 wt% + PEO 3 wt% + LE 90 wt% + zirconia powder (60 wt% relative to total polymer)) / Ceramic-coated separator / Second electrolyte / Anode

[0209] A lithium secondary battery was prepared by replacing the zeolite powder with zirconia powder at a content of 60 wt% based on the total polymer weight of the first electrolyte, and by carrying out the same procedure as in Example 1, except for this.

[0210] Comparative Example 3: Cathode current collector / First electrolyte (TMPTMA 7 wt% + PEO 3 wt% + LE 90 wt% + titania powder (60 wt% relative to total polymer)) / Ceramic-coated separator / Second electrolyte / Anode

[0211] A lithium secondary battery was prepared by replacing the zeolite powder with titania powder at a content of 60 wt% based on the total polymer weight of the first electrolyte, and by carrying out the same procedure as in Example 1, except for this.

[0212] Comparative Example 4: Cathode current collector / First electrolyte (TMPTMA 7 wt% + PEO 3 wt% + LE 90 wt% + silica powder (60 wt% relative to total polymer)) / Ceramic-coated separator / Second electrolyte / Anode

[0213] A lithium secondary battery was prepared by replacing the zeolite powder with silica powder at a content of 60 wt% based on the total polymer weight of the first electrolyte, and by carrying out the same procedure as in Example 1 except for this.

[0214] Comparative Example 5: Cathode current collector / First electrolyte (TMPTMA 7 wt% + PEO 3 wt% + LE 90 wt% + Ceria powder (60 wt% relative to total polymer)) / Ceramic-coated separator / Second electrolyte / Anode

[0215] A lithium secondary battery was prepared in the same manner as in Example 1, except that the content of ceria powder was prepared at 60 wt% based on the total polymer weight of the first electrolyte instead of zeolite powder when preparing the first electrolyte.

[0216] Comparative Example 6: Cathode current collector / First electrolyte (TMPTMA 7 wt% + PEO 3 wt% + LE 90 wt% + alumina powder (60 wt% relative to total polymer)) / Ceramic-coated separator / Second electrolyte / Anode

[0217] A lithium secondary battery was prepared in the same manner as in Example 1, except that the content of alumina powder was prepared at 60 wt% based on the total polymer weight of the first electrolyte instead of zeolite powder when preparing the first electrolyte.

[0218] Evaluation Example 1: Initial Efficiency Evaluation

[0219] After leaving the above-manufactured coin cell at a constant temperature of 25°C for 24 hours, the cell formation process was completed by using a lithium secondary battery charger / discharger (Toyo-System Co., LTD, TOSCAT3500) to charge the cell under constant current conditions of 0.1C to 4.3V and constant voltage conditions with a termination current of 0.05C, and then discharging it under constant current conditions of 0.1C to 2.8V. During the above formation process, the initial efficiency was calculated according to the following formula.

[0220] Initial efficiency (%) = (Discharge capacity in the 1st cycle / 1 st Charge capacity per cycle) × 100

[0221] Evaluation Example 2: Life Evaluation

[0222] After leaving the above-manufactured secondary battery at a constant temperature of 25°C for 24 hours, the cell formation process was completed by using a lithium secondary battery charger / discharger (Toyo-System Co., LTD, TOSCAT3500) to charge the battery under constant current conditions of 0.1C to 4.3V and constant voltage conditions with a termination current of 0.05C, and then discharging it under constant current conditions of 0.1C to 2.8V. The cell formed above was charged and discharged at a current of 1.0C, and the life characteristics were evaluated by calculating the number of cycles at which the capacity retention rate reached 80% according to the following formula, and the results are shown in Table 1.

[0223] Capacity Retention Rate (%) = (Discharge capacity at the Xth cycle / 1 st Discharge capacity per cycle) × 100

[0224] Classification 1 Electrolyte Composition (WJ%) Initial Efficiency (%) Lifespan (Number of Cycles @ 80% Capacity) Example 1 (TMPTMA 7 wt% + PEO 3 wt% + LE 90 wt% (1M LiPF6, EC : DEC = 1 : 1) + Zeolite Powder (60 wt% of total polymer)) 91.3221 Example 2 (TMPTMA 7 wt% + PEO 3 wt% + LE 90 wt% (1M LiPF6, EC : DEC = 1 : 1) + Zeolite Powder (90 wt% of total polymer)) 90.1193 Example 3 (TMPTMA 7 wt% + PEO 3 wt% + LE 90 wt% (1M LiPF6, EC : DEC = 1 : 1) + Zeolite Powder (45 wt% of total polymer)) 89.9187 Example Example 4 (TMPTMA 7 wt% + PEO 3 wt% + LE 90 wt% (1M LiPF6, EC : DEC = 1 : 1) + Zeolite powder (30 wt% of total polymer) 89.1180 Example 5 (TMPTMA 7 wt% + PVDF-HFP 3 wt% + LE 90 wt% (1M LiPF6, EC : DEC = 1 : 1) + Zeolite powder (60 wt% of total polymer) 89.7209 Example 6 (TMPTMA 10 wt% + PEO 1 wt% + LE 89 wt% (1M LiPF6, EC : DEC = 1 : 1) + Zeolite powder (60 wt% of total polymer) 88.5199 Comparative Example 1 (TMPTMA 7 wt% + PEO 3 wt% + LE 90 wt% (1M LiPF6, EC : DEC = 1 : 1) 87.6126 Comparative Example 2 (TMPTMA 7 wt% + PEO 3 wt% + LE 90 wt% (1M LiPF6, EC : DEC = 1 : 1) + zirconia powder (60 wt%) relative to total polymer) 88.1106 Comparative Example 3 (TMPTMA 7 wt% + PEO 3 wt% + LE 90 wt% (1M LiPF6, EC : DEC = 1 : 1) + titania powder (60 wt%) relative to total polymer) 86.4121 Comparative Example 4 (TMPTMA 7 wt% + PEO 3 wt% + LE 90 wt% (1M LiPF6, EC : DEC = 1 : 1) + silica powder (60 wt% relative to total polymer) 84.3145 Comparative Example 5 (TMPTMA 7 wt% + PEO 3 wt% + LE 90 wt% (1M LiPF6, EC : DEC = 1 : 1) + ceria powder (60 wt% relative to total polymer) 87.1117 Comparative Example 6 (TMPTMA 7 wt% + PEO 3 wt% + LE 90 wt% (1M LiPF6, EC : DEC = 1 : 1) + alumina powder (60 wt% relative to total polymer) 88.4133.

[0225] In Table 1, LE stands for Liquid Electrolyte. As shown in Table 1, the lithium secondary battery according to the example was found to have a higher overall initial efficiency and superior lifespan characteristics compared to the lithium secondary battery according to the comparative example by including zeolite powder in the first electrolyte.

[0226] Although preferred embodiments of the present invention have been described above, the present invention is not limited thereto and can be implemented with various modifications within the scope of the claims, the detailed description of the invention, and the attached drawings, and it is obvious that such modifications also fall within the scope of the present invention.

Claims

1. Cathode; anode; A separator disposed between the above cathode and the above anode; and A first electrolyte in contact with the above cathode and the above separator Includes, A lithium secondary battery in which the first electrolyte comprises zeolite powder.

2. In Paragraph 1, A lithium secondary battery, wherein the first electrolyte further comprises a cross-linked polymer and a linear polymer.

3. In Paragraph 2, The above-mentioned cross-linked polymer is a lithium secondary battery corresponding to an acrylic polymer.

4. In Paragraph 3, The above acrylic polymer is a lithium secondary battery formed from PETTA (Pentaerythritol Tetraacrylate), DPHA (dipentaerythritol hexacrylate), TMPTMA (trimethylolpropane trimethacrylate), PETA (Pentaerythritol Triacrylate), DPEPA (Dipentaerythritol Pentaacrylate), DTMPTTA (Dipentaerythritol Tetramethacrylate), ETPTA (Ethoxylated Trimethylolpropane Triacrylate), TMPTA (Trimethylolpropane Triacrylate), TTEGDA (Triethylene Glycol Diacrylate), or any combination thereof.

5. In Paragraph 2, A lithium secondary battery comprising the above linear polymer, a polyethylene oxide (PEO)-based polymer or a polyvinylidene fluoride (PVDF)-based polymer or any combination thereof.

6. In Paragraph 1, A lithium secondary battery in which the content of the zeolite powder is 20 wt% to 100 wt% with respect to the total weight of the polymer of the first electrolyte.

7. In Paragraph 2, A lithium secondary battery in which the weight ratio of the cross-linked polymer to the linear polymer is 2:1 to 10:

1.

8. In Paragraph 1, A lithium secondary battery further comprising a second electrolyte in contact with the anode.

9. In Paragraph 8, The above second electrolyte comprises a liquid electrolyte and a cross-linked polymer, forming a lithium secondary battery.

10. In Paragraph 9, A lithium secondary battery comprising the above-mentioned crosslinked polymer, acrylic, imide, and epoxy types, or any combination thereof.

11. In Paragraph 9, The above liquid electrolyte comprises a lithium salt and an organic solvent, forming a lithium secondary battery.

12. In Paragraph 9, A lithium secondary battery in which the content of the cross-linked polymer is included in a range of 2 wt% to 20 wt% with respect to the total weight of the second electrolyte.

13. In Paragraph 1, A lithium secondary battery having a ceramic coating on one surface facing the positive electrode of the separator.

14. In Paragraph 13, The ceramics mentioned above are aluminum oxide (Al2O3), zirconium oxide (ZrO2), silicon dioxide (SiO2), titanium dioxide (TiO2), lithium phosphate (Li3PO4), and lanoleum-lithium-zirconium oxide (Li7La3Zr2O). 12 A lithium secondary battery comprising ), aluminum lithium oxide (LiAlO2), iron oxide (Fe2O3), chromium trioxide (CrO3), boehmite (AlO(OH)), or any combination thereof.

15. In Paragraph 1, The above separator is a lithium secondary battery corresponding to a polyolefin-based polymer.

16. In Paragraph 15, A lithium secondary battery comprising the above polyolefin-based polymer, polyethylene (PE) and polypropylene (PP) or any combination thereof.

17. In Paragraph 1, The above separator has a porous structure. A lithium secondary battery having a porosity of 50% or more of the above-mentioned porous structure.

18. In Paragraph 1, A lithium secondary battery in which the thickness of the separator and the thickness of the first electrolyte are 1:1.5 to 1:

5.

19. In Paragraph 8, The first electrolyte penetrates into the pores inside the cathode and the pores inside the separator, and A lithium secondary battery in which the above-mentioned second electrolyte penetrates into the pores inside the anode.

20. Cathode; anode; A separator disposed between the above cathode and the above anode; A composite polymer electrolyte in contact with the above cathode and the above separator; and Gel polymer electrolyte in contact with the above anode Includes, The above composite polymer electrolyte includes zeolite powder, and The above gel polymer electrolyte is a lithium secondary battery comprising a liquid electrolyte and a cross-linked polymer.

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