Polymer solid electrolyte and all-solid-state battery containing the same

Abstract

The present invention relates to a polymer solid electrolyte and an all-solid-state battery. The polymer solid electrolyte includes a polymer including a PEO (polyethylene oxide) copolymer containing cross-linkable functional groups, and a polar compound, at least some of the cross-linkable functional groups forming cross-links with each other, forming a three-dimensional network structure of the polymer, and the polar compound is contained in the three-dimensional network structure in a gaseous state or bonded to the polymer chain, and can satisfy predetermined properties.

Description

[Technical Field]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0132781 dated October 14, 2022 and Korean Patent Application No. 10-2023-0136064 dated October 12, 2023, and all contents disclosed in the documents of said Korean patent applications are incorporated herein by reference.

[0002] The present invention relates to a polymer solid electrolyte and an all-solid-state battery including the same. [Background technology]

[0003] Lithium-ion batteries using liquid electrolytes have a structure in which the negative electrode and positive electrode are separated by a separator, and if the separator is damaged due to deformation or external impact, a short circuit may occur, which can lead to risks such as overheating or explosion. Therefore, the development of a solid electrolyte that can ensure safety in the field of lithium-ion secondary batteries is a very important issue.

[0004] Lithium secondary batteries using solid electrolytes have the advantages of increased battery safety, improved reliability due to the prevention of electrolyte leakage, and ease of manufacturing thin batteries. Furthermore, lithium metal can be used as the anode, improving energy density. This makes them promising for applications in compact secondary batteries as well as high-capacity secondary batteries for electric vehicles, and they are attracting attention as next-generation batteries.

[0005] Among solid electrolytes, a composite electrolyte of polyethylene oxide (PEO) and lithium salt has the advantage of being more fire-resistant than existing liquid electrolytes, but the high crystallinity of polyethylene oxide (PEO) has limited the ability to produce a polymer solid electrolyte with improved ionic conductivity. In other words, the high crystallinity of polymers inhibits the chain mobility of polymers, restricting the movement of lithium ions within the polymer solid electrolyte, making it difficult to improve the ionic conductivity of the polymer solid electrolyte.

[0006] To overcome these limitations of conventional polymer solid electrolytes, technologies have been developed to improve the ionic conductivity of polymer solid electrolytes by modifying the structure of crystalline polymers or adding a separate plasticizer to the polymer to improve the mobility of polymer chains. However, it can be difficult to improve the ionic conductivity of solid polymer electrolytes manufactured using the polymer structural modification or plasticizer addition methods to exceed 0.1 mS / cm.

[0007] Attempts have been made to improve ionic conductivity by directly adding a liquid electrolyte or a solvent to the polymer solid electrolyte. However, these attempts are not pure solid electrolytes for all-solid-state batteries, but are categorized as techniques for electrolytes for semi-solid batteries in which a solid and a liquid coexist. As a result, the improvement in ionic conductivity is insufficient, and a considerable amount of liquid electrolyte still needs to be injected, making it difficult to completely resolve issues of reduced safety due to leakage, etc.

[0008] Therefore, in addition to polymer solid electrolytes prepared by modifying the polymer structure, adding a separate plasticizer, or immersing a solid electrolyte in a liquid electrolyte, there is a need to develop a technology that can improve the ionic conductivity of the electrolyte as a pure solid electrolyte for all-solid-state batteries. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 1994-124713 Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention provides a polymer solid electrolyte that can improve ionic conductivity even when a trace amount of a polar compound (for example, a polar solvent compound) is added to the polymer solid electrolyte in a non-liquid state.

[0011] Another object of the present invention is to provide an all-solid-state battery that includes the polymer solid electrolyte and exhibits improved ionic conductivity. [Means for solving the problem]

[0012] According to one embodiment of the present invention, there is provided a polymer solid electrolyte that satisfies the following formula 1, which includes a polymer including a PEO (polyethylene oxide) copolymer having cross-linkable functional groups and a polar compound, wherein at least a portion of the cross-linkable functional groups form cross-links with each other, the polymer forming a three-dimensional network structure, and the polar compound is contained in the three-dimensional network structure in a gaseous state or is bonded to the polymer chain:

[0013]

number

[0014] In the above equation 1, t R is the relaxation time of the polymer chain, t D is the diffusion time of the polar compound within the polymer chain, and is defined by the following equation 2:

[0015]

number

[0016] In the above equation 2, D is the diffusion coefficient of the polar compound within the polymer chain, and is 10 -9 or 10 -6 cm 2 / s, and L is the thickness of the polymer solid electrolyte, which is 5 to 500 μm.

[0017] In such a polymer solid electrolyte, the gaseous polar compound may be dispersed among the polymer chains forming the three-dimensional network structure, or may be adsorbed or bound to the surface or interior of the polymer chains.

[0018] The polymer solid electrolyte may further include a cross-linking agent, and in this case, at least a portion of the cross-linkable functional groups may form cross-links with each other via the cross-linking agent.

[0019] In the polymer solid electrolyte, the PEO-based copolymer may contain one or more cross-linkable functional groups. The cross-linkable functional groups are bonded to the polymer chain of the PEO-based copolymer via an alkylene linker or alkylene oxide linker having 0 to 10 carbon atoms (wherein an alkylene linker having 0 carbon atoms represents a single bond), and may be a functional group selected from the group consisting of a hydroxyl group, a carboxyl group, an isocyanate group, a nitro group, a cyano group, an amine group, an amide group, an epoxy group, and an allyl group.

[0020] The polymer solid electrolyte may further include a lithium salt dispersed on the polymer forming the three-dimensional network structure, and the lithium salt may be present in a state where at least a portion of the lithium salt is dissociated into cations and anions. The cations and / or anions may be present in a state bound to the polymer and may migrate during charge / discharge of the battery.

[0021] In a specific embodiment, the PEO (polyethylene oxide) copolymer of the polymer solid electrolyte may be a copolymer including repeating units of the following Chemical Formulas 1 to 3:

[0022] [ka]

[0023] In the above formulas 1 to 3, R1 is -CH2-O-(CH2-CH2-O) k -R3, k is 0 to 20, R3 is an alkyl group having 1 to 5 carbon atoms, R2 is a substituent in which one or more crosslinkable functional groups selected from the group consisting of a hydroxyl group, a carboxyl group, an isocyanate group, a nitro group, a cyano group, an amine group, an amide group, an epoxy group, and an allyl group are bonded to a polymer chain via an alkylene linker or alkylene oxide linker having 0 to 10 carbon atoms (however, an alkylene linker having 0 carbon atoms represents a single bond), l, m, and n are the number of repeating units, l and n are each independently an integer of 1 to 1000, and m is an integer of 0 to 1000.

[0024] Meanwhile, in such a polymer solid electrolyte, the content of the polar compound may be 0.1 wt % or more and less than 10 wt % based on the total weight of the polymer solid electrolyte.

[0025] The polar compound may include one or more compounds selected from the group consisting of carbonate-based compounds and sulfonyl-based compounds, or may be a polar compound contained in a gaseous state derived from a carbonate-based solvent and a sulfonyl-based solvent.

[0026] Meanwhile, the polymer solid electrolyte may further include a ceramic compound dispersed within the three-dimensional network structure of the polymer. Such a ceramic compound may include an oxide-based solid electrolyte of lithium metal oxide or lithium metal phosphate, more specifically, one or more oxide-based solid electrolytes selected from the group consisting of lithium-lanthanum-zirconium oxide (LLZO) compounds, lithium-silicon titanium phosphate (LSTP) compounds, lithium-lanthanum-titanium oxide (LLTO) compounds, lithium-aluminum-titanium phosphate (LATP) compounds, lithium-aluminum-germanium phosphate (LAGP) compounds, and lithium-lanthanum-zirconium-titanium oxide (LLZTO) compounds.

[0027] Meanwhile, according to another embodiment of the present invention, there is provided an all-solid-state battery including a positive electrode, a negative electrode, and an electrolyte layer interposed between the positive electrode and the negative electrode and including the polymer solid electrolyte of the above-described embodiment. [Effects of the Invention]

[0028] The polymer solid electrolyte according to an embodiment of the present invention can maintain the original structural characteristics of the polymer without deformation or destruction of the material, and can improve the ionic conductivity of the polymer solid electrolyte by improving the mobility of the polymer chains.

[0029] In particular, the polymer solid electrolyte contains a trace amount of polar compound in a gaseous state by vapor deposition, which can improve the ionic conductivity and mechanical properties of the polymer solid electrolyte. Furthermore, when a polar solvent and a polar compound derived therefrom are contained within the polymer solid electrolyte by vapor deposition, gelation is prevented, the relaxation time of the internal polymer chains is delayed, and the mobility of the polymer chains is improved, thereby improving the ionic conductivity without deteriorating the mechanical properties.

[0030] In particular, the inventors have found that not only the relaxation time of the polymer chains but also the time it takes for the vapor-deposited polar compounds to diffuse within the polymer chains is related to ionic conductivity, and therefore, it has been found that the improvement in ionic conductivity of the polymer solid electrolyte can be maximized by controlling the relaxation time of the polymer chains and the diffusion time of the polar compounds contained in the polymer solid electrolyte.

[0031] In addition, the polymer solid electrolyte further contains a uniformly dispersed ceramic compound, which can further improve the ionic conductivity thereof. DETAILED DESCRIPTION OF THE INVENTION

[0032] Hereinafter, specific embodiments of the present invention will be described in more detail for better understanding of the present invention.

[0033] The terms and words used in this specification and claims should not be interpreted in a limited way to their ordinary or dictionary meanings, but should be interpreted in a way that is consistent with the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concept of the term in order to best explain his or her invention.

[0034] As used herein, the term "bonding," i.e., in relation to the form in which a polar compound is "bonded" to a polymer chain, e.g., a PEO-based copolymer chain, broadly refers to a form in which a polar compound in a gaseous state, i.e., a polar solvent molecule, is fixed to a polymer chain by vapor deposition of a polar solvent. In other words, the term "bonding" is not limited to a specific type of physical bond, chemical bond, etc., but includes a state in which the polar compound is fixed by various bonds including these physical bonds, chemical bonds, etc., a state in which the polar compound is fixed by simple adhesion such as adsorption, or a state in which the polar compound is included in a three-dimensional network structure formed by cross-linking of the polymer and is fixed adjacent to the polymer chain or cross-linked structure.

[0035] The term "three-dimensional network structure" as used herein refers to a structure including a three-dimensional frame and an internal space formed by the frame, and the frame may include polymer chains including crosslinks formed by the crosslinking functional groups, for example, crosslinks between crosslinking functional groups and / or crosslinks between crosslinking functional groups and a crosslinking agent. The three-dimensional network structure may also be referred to as a crosslinked structure.

[0036] As used herein, the expression "existing or being contained in a gaseous state" for a polar compound (polar solvent) in a polymer solid electrolyte refers to the polar compound being deposited in a vapor state, as distinct from the liquid-injected electrolyte, immediately after the preparation of the polymer solid electrolyte or during the charge / discharge process of an all-solid-state secondary battery containing the same. However, depending on the storage or operating conditions of the polymer solid electrolyte and / or secondary battery, the vapor-deposited polar compound may be locally or temporarily liquefied. Even in such cases, the vapor-deposited polar compound exhibits higher mobility than the polar solvent injected in a liquid state and thus exhibits a different state from the liquid-state polar solvent, and therefore can also be considered to be present or contained in the "gas state."

[0037] Furthermore, as used herein, the term "polymer solid electrolyte" refers to a polymer solid electrolyte that includes, as essential components, (i) a polymer including a PEO (polyethylene oxide) copolymer containing a cross-linkable functional group and a polar compound, or (ii) a ceramic compound in addition to (i). The polymer solid electrolyte (ii) that further includes a ceramic compound in addition to (i) can also be referred to as a "composite solid electrolyte."

[0038] Meanwhile, to improve the ionic conductivity of a solid electrolyte, a solid electrolyte has previously been immersed in or supported by a liquid electrolyte or solvent, or the liquid electrolyte or solvent has been directly injected into the solid electrolyte in a liquid state. While adding a liquid electrolyte or solvent directly to a solid electrolyte does improve the ionic conductivity of the solid electrolyte, this only increases the ionic conductivity of the solid electrolyte based on the high ionic conductivity of the liquid itself, and the improvement is insufficient, requiring the injection of a substantial amount of liquid electrolyte. In other words, lithium ion conduction is driven by the liquid electrolyte added to the solid electrolyte rather than the inherent physical properties of the solid electrolyte, far from improving the physical properties of the solid electrolyte itself. Furthermore, when a liquid electrolyte or solvent is directly added or injected into a polymer solid electrolyte in a liquid state, unexpected side reactions between the polymer and the liquid can damage the polymer chains or break bonds within the polymer, causing the structure of the solid electrolyte to collapse, resulting in a decrease in ionic conductivity.

[0039] In addition, when a solvent or liquid electrolyte is directly injected into a solid electrolyte, the liquid molecules rapidly diffuse into the solid electrolyte, causing rapid relaxation of polymer chains and promoting gelation on the surface, which may result in a decrease in mechanical properties and may not completely resolve issues such as leakage of the liquid electrolyte.

[0040] In addition, the conventional technology disclosed in Japanese Patent Application Laid-Open No. 1994-124713 involves vapor deposition of a solvent onto a general PEO (polyethylene oxide) polymer, which has the problem that the internal structure of the polymer collapses due to the lack of a cross-linked structure, making it impossible to ensure ionic conductivity.

[0041] Therefore, the present inventors applied a method of vapor deposition of a polar compound derived from a polar solvent onto a polymer solid electrolyte including a polymer cross-linked with a polyethylene oxide (PEO)-based copolymer modified with cross-linkable functional groups. In one embodiment, the polymer solid electrolyte thus prepared includes a polymer including a PEO-based copolymer with cross-linkable functional groups and a polar compound, where at least some of the cross-linkable functional groups form cross-links with each other, forming a three-dimensional network structure of the polymer. The polar compound may be contained within the three-dimensional network structure in a gaseous state or may be bonded to the polymer chain.

[0042] It was confirmed that this polymer solid electrolyte contains a small amount of polar compounds derived from the polar solvent in a gaseous state and exhibits improved ionic conductivity. This is thought to be because the polar compounds in the gaseous state affect the physical properties of the PEO-based copolymer, such as its crystallinity, increasing the chain mobility of the polymer, thereby improving the conductivity of lithium ions contained in the polymer solid electrolyte.

[0043] Therefore, the polymer solid electrolyte of an embodiment exhibits improved ionic conductivity without substantially containing a liquid polar solvent or electrolyte, and can greatly contribute to the development of all-solid-state batteries with excellent physical properties.

[0044] Hereinafter, a polymer solid electrolyte according to an embodiment of the present invention will be described in detail.

[0045] Polymer solid electrolyte As described above, the polymer solid electrolyte of one embodiment includes a polymer including a polyethylene oxide (PEO) copolymer having cross-linkable functional groups and a polar compound, wherein at least a portion of the cross-linkable functional groups of the copolymer form cross-links with each other, the polymer forming a three-dimensional network structure, and the polar compound in a gaseous state is contained within the three-dimensional network structure or has a structure bonded to the polymer chain.

[0046] In a specific example, the gaseous polar compound may be dispersed among the polymer chains forming the three-dimensional network structure, or may be adsorbed or bound to the surface or interior of the polymer chains.

[0047] Such a polymer solid electrolyte includes a polar compound contained in or bonded to a trace amount of gaseous state by vapor deposition, as described below. Such a polymer solid electrolyte can be identified, for example, by the absence of liquid-phase components on the surface of the electrolyte layer when an electrolyte layer containing the same is separated from an all-solid-state battery and observed visually or with an electron microscope. In contrast, when a liquid polar solvent or electrolyte solution is injected into the polymer solid electrolyte, a liquid-phase component or a component exhibiting wettability can be observed on the surface of the electrolyte layer. Furthermore, as will be seen in the examples described below, a polymer solid electrolyte containing the polar compound vapor-deposited in a gaseous state exhibits significantly higher ionic conductivity than a polymer solid electrolyte containing the polar compound vapor-deposited in a gaseous state. A comparison of ionic conductivities also confirms that the polar compound is vapor-deposited in a gaseous state.

[0048] Furthermore, the polymer solid electrolyte of one embodiment satisfies the characteristics defined by the following formula 1:

[0049]

number

[0050] In the above equation 1, t R is the relaxation time of the polymer chain, t D is the diffusion time of the polar compound within the polymer chain, and is defined by the following equation 2:

[0051]

number

[0052] In the above equation 2, D is the diffusion coefficient of the polar compound within the polymer chain, and is 10 -9 or 10 -6 cm 2 / s, and L is the thickness of the polymer solid electrolyte, which is 5 to 500 μm.

[0053] Equation 1 was derived based on the fact that the behavior of the polar compound and the resulting polymer is related to the improvement of the ionic conductivity of the polymer solid electrolyte according to the embodiment.

[0054] Specifically, the above formula 1 expresses the relaxation time (t R ) and the diffusion time (t D ) Satisfying the above formula 1 means that the relaxation time of the polymer becomes relatively long, the mobility of the polar compound in a gaseous state increases, and the diffusion time becomes short. As shown in the examples below, it has been confirmed that satisfying this characteristic can significantly improve the ionic conductivity of the polymer solid electrolyte.

[0055] For example, the relaxation time (t R ) means that the more the polymer chains are delayed, the greater the fluidity of the polymer chains and the greater the mobility of the polymer chains. R ) is delayed and the larger the value, the more advantageous it is for improving ionic conductivity. D ) may have an effect of improving ionic conductivity as the length of the electrode becomes shorter.

[0056] Therefore, the relaxation time of the polymer chain (t R ) and the diffusion time (t D) satisfies the range defined by the above formula 1, the ionic conductivity of the polymer solid electrolyte can be improved. The relaxation time may be 12 hours or more and 120 hours or less.

[0057] The characteristic of Formula 1 can be achieved by the polymer solid electrolyte of the present embodiment, which is prepared by vapor deposition of a polar solvent (polar compound). It can be presumed that the vapor-deposited polar compound improves the mobility of polymer chains, and that the characteristic is achieved because the polar compound is contained in a gaseous state and its diffusion time is shortened.

[0058] For example, when Equation 1 is satisfied, the gaseous polar compound exhibits Fickian diffusion behavior when it diffuses after being adsorbed into the polymer. Due to Fickian diffusion, the polar compound forms a uniform concentration profile as it diffuses within the polymer. This allows for the inclusion of trace amounts of the gaseous polar compound on the surface or inside of the polymer chains, improving the fluidity of the polymer chains without deforming the internal structure of the polymer, thereby improving the ionic conductivity of the polymer solid electrolyte.

[0059] On the other hand, if the polar solvent is outside the range of Equation 1, it can be assumed that the polar solvent is injected in a liquid state and exhibits non-Fickian diffusion behavior. Due to non-Fickian diffusion behavior, the polar solvent may be rapidly absorbed into the polymer, causing gelation on the polymer surface, and the non-uniform concentration distribution inside the polymer may reduce polymer chain mobility, resulting in a limited effect on increasing the ionic conductivity of the polymer solid electrolyte.

[0060] Based on the above principle, a polymer solid electrolyte that satisfies the characteristics of Equation 1 can exhibit improved ionic conductivity. By satisfying Equation 1, it can be indirectly confirmed that the polymer solid electrolyte contains a vapor-deposited polar compound in a gaseous state.

[0061] On the other hand, in the relational expression of the above-mentioned formula 1, the t R The relaxation time of a polymer chain refers to the relaxation time of the polymer chain, and can refer to the time it takes for the polymer chain to return to an equilibrium or normal state after being deformed by the vapor deposition of the polar solvent (polar compound). In general, the relaxation time may refer to the time it takes for a polymer system in an equilibrium state to reach another equilibrium state after being switched to a non-equilibrium state by an external perturbation. For example, an example of a method and conditions for measuring the relaxation time is described in "Tapabrata Dam, et al., The ionic transport mechanism and coupling between the ion conduction and segmental relaxation processes of PEO" 20 -LiCF3SO3-based ion conducting polymer clay composites,” Phys. Chem. Chem. Phys 18, 19955-19965 (2016), etc.

[0062] t in the above formula 1 R In the example, the vapor deposition of a polar solvent corresponds to the external disturbance, and the vapor deposition time (t) is t R At a time (t=t R ) may signal that the polymer system has reached a stable equilibrium state.

[0063] The relaxation time may generally vary depending on the temperature. The ionic conductivity of a polymer solid electrolyte increases as the temperature increases. Therefore, when the vapor deposition process is performed at a high temperature, the increase in ionic conductivity may be the result of the combined effects of temperature and vapor deposition. To eliminate the coupling effect in experimental results and accurately determine the relaxation time of polymer chains induced by vapor deposition, the vapor deposition process may be performed at room temperature.

[0064] t D is the diffusion time of the polar compound within the polymer chain, and is the time it takes for the polar compound having a certain diffusion coefficient to diffuse into the interior of a polymer having a certain thickness. The polymer may be in the form of a polymer film.

[0065] In the above equation 2, D is the diffusion coefficient of the polar compound within the polymer chain, and is 10 -9 or 10 -6 cm 2 / s. -9 cm 2 If the diffusion rate is less than 10 / s, the diffusion of polar compounds inside the polymer chains may be too slow, making the vapor deposition process difficult. -6 cm 2 If the D exceeds 1 / s, the rate at which the polar compound diffuses and evaporates increases, which can promote gelation of the polymer. The D may be used as a fitting parameter.

[0066] The D can be calculated by the following formula 3.

[0067]

number

[0068] M(t) is the evaporation amount of the polar compound contained in the polymer solid electrolyte over time, and M ∞is the maximum or saturated value of the polar compound that can be contained in the polymer solid electrolyte and is 0.005 to 0.5; L is, for example, the thickness of the film-shaped polymer solid electrolyte and is 5 μm to 500 μm; and t is the time at which the liquid evaporation rate is measured.

[0069] After measuring M(t), the fitting parameter D can be obtained by fitting using Equation 3.

[0070] L is the thickness of the polymer solid electrolyte obtained in a film form, and may be, for example, 5 to 500 μm. If L is less than 5 μm, swelling due to the polar compound reduces the mechanical strength of the polymer solid electrolyte, making it difficult to handle or causing it to break. If L is more than 500 μm, the increased thickness may act as resistance within the battery, potentially resulting in a decrease in battery performance. The method or device for measuring L is not particularly limited as long as it is capable of measuring the thickness of an object. For example, L can be measured using a general micrometer or by analyzing a cross section using a scanning electron microscope (SEM).

[0071] Meanwhile, in the polymer solid electrolyte according to one embodiment, the crosslinkable functional group may be directly bonded to the backbone of the PEO-based copolymer or may be bonded via an alkylene or alkylene oxide linker. Thus, the crosslinkable functional group may be bonded via an alkylene linker or alkylene oxide linker having 0 to 10 carbon atoms (wherein an alkylene linker having 0 carbon atoms represents a single bond), and may be one or more groups selected from the group consisting of a hydroxyl group, a carboxyl group, an isocyanate group, a nitro group, a cyano group, an amine group, an amide group, an epoxy group, and an allyl group.

[0072] In one embodiment of the present invention, the cross-linking functional groups may be of two or more types. The cross-linking functional groups may be the same or different, preferably different. When the cross-linking functional groups are different, multiple types of repeating units each containing these functional groups may be included. Furthermore, when multiple types of cross-linking functional groups are included, it may be easier to control the mobility and ionic conductivity of the polymer chain.

[0073] The crosslinkable functional group means a functional group that can form a crosslink between itself and / or with itself via a crosslinking agent, and may be attached to the main chain of a polymer chain in the form of a side chain.

[0074] In a more specific embodiment, the PEO-based copolymer having a cross-linking functional group may be a copolymer including repeating units of the following Chemical Formulas 1 to 3:

[0075] [ka]

[0076] In the above formulas 1 to 3, R1 is -CH2-O-(CH2-CH2-O) k -R3, k is 0 to 20, and R3 is an alkyl group having 1 to 5 carbon atoms; R2 represents a substituent in which one or more crosslinkable functional groups selected from the group consisting of a hydroxyl group, a carboxyl group, an isocyanate group, a nitro group, a cyano group, an amine group, an amide group, an epoxy group, and an allyl group are bonded to a polymer chain via an alkylene linker or alkylene oxide linker having 0 to 10 carbon atoms (provided that an alkylene linker having 0 carbon atoms represents a single bond); l, m, and n are the number of repeats of the repeating unit, l and n are each independently an integer of 1 to 1000, and m is an integer of 0 to 1000.

[0077] For example, the cross-linkable functional group of R2 may form a polymer having a matrix form of a three-dimensional network structure formed by the cross-linking. The formation of a three-dimensional network structure by the cross-linking may improve the mechanical properties of the polymer solid electrolyte. In addition, the gaseous polar compound may be contained or bonded within the three-dimensional network structure, thereby providing a polymer solid electrolyte having improved ionic conductivity, according to an embodiment.

[0078] It is also clear that the PEO-based copolymer may contain two or more repeating units of Chemical Formula 3 in which R2 is a cross-linking functional group different from each other, and may also contain one or more repeating units of Chemical Formula 2.

[0079] If l, m, and n are each less than 1, it may be difficult to form a polymer due to a small molecular weight, and if l, m, and n are each more than 1000, the viscosity increases, reducing solubility during preparation of a polymer solution, making molding for preparing a polymer solid electrolyte difficult. In particular, if the number of repeating units containing cross-linkable functional groups among l, m, and n exceeds 1000, the degree of cross-linking may increase excessively, reducing the mobility of polymer chains and potentially reducing the ionic conductivity of the polymer solid electrolyte.

[0080] As used herein, a "hydroxy group" refers to an --OH group.

[0081] As used herein, a "carboxyl group" refers to a -COOH group.

[0082] As used herein, an "isocyanate group" refers to a -N=C=O group.

[0083] As used herein, a "nitro group" refers to a -NO2 group.

[0084] As used herein, a "cyano group" refers to a -CN group.

[0085] As used herein, an "amide group" refers to -C(=O)NR'R'', where R' and R'' can each independently be hydrogen or a C1 to C5 alkyl group, or R' and R'' together with the N atom to which they are attached can form a heterocycle having C4 to C8 atoms in the ring structure.

[0086] As used herein, the term "amine group" may be selected from the group consisting of monoalkylamine groups, monoarylamine groups, monoheteroarylamine groups, dialkylamine groups, diarylamine groups, diheteroarylamine groups, alkylarylamine groups, alkylheteroarylamine groups, and arylheteroarylamine groups. The number of carbon atoms is not particularly limited, but preferably ranges from 1 to 30. Specific examples of the amine group include, but are not limited to, methylamine groups, dimethylamine groups, ethylamine groups, diethylamine groups, phenylamine groups, naphthylamine groups, biphenylamine groups, dibiphenylamine groups, anthracenylamine groups, 9-methylanthracenylamine groups, diphenylamine groups, phenylnaphthylamine groups, ditolylamine groups, phenyltolylamine groups, triphenylamine groups, biphenylnaphthylamine groups, phenylbiphenylamine groups, biphenylfluorenylamine groups, phenyltriphenylenylamine groups, and biphenyltriphenylenylamine groups. Furthermore, the term "amino group" refers to -NH.

[0087] As used herein, an "allyl group" refers to the group -CH2-CH=CH2.

[0088] The weight-average molecular weight (Mw) of the copolymers including Formulas 1 to 3 may be 100,000 g / mol to 2,000,000 g / mol, specifically, 100,000 g / mol or more, 200,000 g / mol or more, or 300,000 g / mol or more, or 1,600,000 g / mol or less, 1,800,000 g / mol or less, or 2,000,000 g / mol or less. If the weight-average molecular weight (Mw) of the copolymer is less than 100,000 g / mol, the mechanical properties of the resulting polymer solid electrolyte may not be satisfactory. If the weight-average molecular weight (Mw) of the copolymer is more than 2,000,000 g / mol, the viscosity increases, reducing solubility during polymer solution preparation, making molding for producing a polymer solid electrolyte difficult. In addition, the ionic conductivity of the polymer solid electrolyte may decrease due to increased crystallinity and decreased chain mobility within the polymer solid electrolyte.

[0089] In particular, when the repeating number of the repeating unit of Formula 3 containing a cross-linking functional group among l, m, and n exceeds 1000, the degree of cross-linking increases excessively, which may reduce the mobility of the polymer chain and decrease the ionic conductivity of the polymer solid electrolyte.

[0090] The copolymer may also be a random copolymer or a block copolymer.

[0091] In a specific embodiment of the present invention, the polar compound may be contained in or bound to the surface or interior of the polymer chain in a gaseous state. Specifically, the polar compound in a gaseous state may be diffused or dispersed among the polymer chains forming the three-dimensional network structure by the cross-linking, or may be adsorbed or bound to the surface or interior of the polymer chain.

[0092] The polar compound may be a gas molecule of a polar solvent used in the vapor deposition process, and may be adsorbed into the polymer during vapor deposition and then diffused into the polymer chains, and may be bonded to the polymer chains or may be dispersed or dispersed in the internal space between the polymer chains. The polar compound may be bonded to the polymer chains or dispersed in the internal space between the polymer chains, thereby improving the ionic conductivity of the final polymer solid electrolyte.

[0093] Specifically, the polar compound bonded to or contained between the polymer chains can act as a plasticizer to plasticize the polymer. The plasticized polymer can increase the amorphous region inside, thereby improving the mobility of the polymer chains. The increased mobility of the polymer chains increases the ion hopping effect inside the polymer, thereby improving the ionic conductivity of the polymer solid electrolyte.

[0094] In addition, the polar compound can act as an intermediate for smooth ion transport through ion hopping. Because the affinity between lithium ions and polar compounds is stronger than the affinity between lithium ions and the ether oxygen of the PEO-based copolymer, lithium ions can be transported more quickly and easily within the polymer with the polar compound adsorbed. In other words, the influx of polar compounds into the polymer increases the cation solvation effect of lithium ions, improving ion mobility and, therefore, the ionic conductivity of the polymer solid electrolyte.

[0095] The polar compound may include one or more compounds selected from the group consisting of carbonate compounds and sulfonyl compounds.

[0096] Specifically, the polar compound may include one or more compounds selected from the group consisting of ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethylene carbonate (EC), propylene carbonate (PC), vinylene carbonate (VC), and sulfolane, or a combination thereof.

[0097] The content of the polar compound may be 0.1 wt % or more and less than 10 wt %, based on the total weight of the polymer solid electrolyte. For example, the content of the polar compound may be 0.1 wt % or more, 1 wt % or more, or 5 wt % or less, 6 wt % or less, 7 wt % or less, 8 wt % or less, 9 wt % or less, or less than 10 wt %. If the content of the polar compound is less than 0.1 wt %, it is difficult to induce a change in the internal chain conformation of the polymer, and the ionic conductivity of the polymer solid electrolyte is not improved. If the content of the polar compound is 10 wt % or more, the polymer solid electrolyte may have a high liquid content, resulting in a semi-solid battery. In addition, the mechanical strength of the polymer solid electrolyte may be reduced due to gelation of the polymer.

[0098] In one embodiment of the present invention, the polymer solid electrolyte may include cross-links between cross-linkable functional groups. The polymer solid electrolyte may further include a cross-linking agent, and may further include cross-links between the cross-linking agent and the cross-linkable functional groups. For example, at least some of the cross-linkable functional groups may form cross-links with each other via the cross-linking agent to form the three-dimensional network structure.

[0099] The crosslink may be a urethane crosslink, an ester crosslink, a hydrogen bond, or a bond formed by a radical polymerization reaction of a vinyl group at the end of an allyl group (-CH-CH=CH), but is not limited to these examples.

[0100] Furthermore, when a crosslinking agent is added in the preparation process of the polymer solid electrolyte, a crosslinking bond may be formed between the crosslinking agent and the crosslinkable functional group, and the crosslinking bond may be a hydrogen bond, a bond due to Lewis acid-base interaction, an ionic bond, a coordinate bond, or a bond formed by radical polymerization.

[0101] The crosslinking agent is not particularly limited as long as it is a polyfunctional crosslinking agent that can form a crosslink with the crosslinkable functional group. For example, the crosslinking agent may be trimethylolpropane trimethacrylate, polyethylene glycol diacrylate (poly(ethylene glycol) diacrylate), polyethylene glycol dimethacrylate (poly(ethylene glycol) dimethacrylate), ethylene glycol dimethylacrylate (hereinafter referred to as "EGDMA"), 1,3-diisopropenylbenzene (DIP), 1,4-diacryloyl piperazine, 2-(diethylamino)ethyl methacrylate, 2,6-bisacryloylamidopyridine, 3-(acryloyloxy)-2-hydroxypropyl methacrylate, 3,5-bis(acrylamido)benzic acid (3,5-bis(acryloylamido)benzoic acid, 3-aminopropyltriethoxysilane, 3-isocyanatopropyltriethoxysilane, 3-methylacryloxypropyl trimethoxysilane, bis-(1-(tert-butylperoxy)-1-methylethyl)-benzene, dicumyl peroxide, dimethacrylate, divinylbenzene, ethylene glycol maleic rosinate acrylate acrylate, glycidylmethacrylate, hydroxyquinoline, iphenyldiethoxysilane, maleic rosin glycol acrylate, methylene bisacrylamide, N,N'-1,4-phenylenediacrylamine, N,O-bisacryloyl-phenylalaninol, N,O-bismethacryloylethanolamineThe crosslinking agent may be one or more polyfunctional crosslinking agents selected from the group consisting of 0-bismethacryloyl ethanolamine, pentaerythritol triacrylate, phenyltrimethoxysilane, tetramethoxysilane, tetramethylene, tetraethoxysilane, and triallyl isocyanurate, for example, a polyvalent compound having two or more functional groups.

[0102] The crosslinking agent may be included in an amount of 1 to 30 parts by weight based on 100 parts by weight of the PEO copolymer having a crosslinkable functional group. If the content of the crosslinking agent is less than 1 part by weight, crosslinking with the crosslinkable functional group may not be sufficient, while if the content is more than 30 parts by weight, crosslinking may be excessive, which may reduce the mobility of polymer chains and thereby reduce ionic conductivity.

[0103] In one embodiment of the present invention, the polymer solid electrolyte may further include a lithium salt. The lithium salt may be present in the internal space between the polymer chains in a dissociated ionic state, thereby improving the ionic conductivity of the polymer solid electrolyte. At least a portion of the cations and / or anions dissociated from the lithium salt may be present in a state bound to the polymer chains, thereby exhibiting mobility during charge / discharge of the battery.

[0104] The lithium salts include (CF3SO2)2NLi (Lithium bis(trifluoromethanesulphonyl)imide, LiTFSI), (FSO2)2NLi (Lithium bis(fluorosulfonyl)imide, LiFSI), LiNO3, LiOH, LiCl, LiBr, LiI, LiClO4, LiBF4, and LiB 10 Cl 10, LiPF6, LiCF3SO3, LiCF3CO2, LiAsF6, LiSbF6, LiAlCl4, CH3SO3Li, CF3SO3Li, LiSCN, LiC(CF3SO2)3, lithium chloroborane, lithium lower aliphatic carboxylate, and lithium tetraphenylborate.

[0105] The lithium salt may be included in an amount of 25 to 45 parts by weight, specifically, 25 parts by weight or more, 30 parts by weight or more, or 35 parts by weight or more, or 40 parts by weight or less, or 45 parts by weight or less, based on 100 parts by weight of the PEO-based copolymer having a cross-linkable functional group. If the content of the lithium salt is less than 25 parts by weight, the ionic conductivity of the polymer solid electrolyte may be reduced, and if it exceeds 45 parts by weight, the mechanical strength may be reduced.

[0106] Meanwhile, the polymer solid electrolyte according to the above-described embodiment may further include a ceramic compound dispersed within the three-dimensional network structure of the polymer. The ceramic compound has lithium ion transport ability to improve the conductivity of lithium ions, and preferably contains lithium atoms but can transport lithium ions without storing lithium, thereby improving the ionic conductivity of the polymer solid electrolyte.

[0107] In addition, the ceramic compound may be included among the cross-linked polymer chains, for example, in a uniformly dispersed state within the three-dimensional network structure. The ceramic compound may be added during the cross-linking process and may be uniformly dispersed without aggregation among the polymer chains formed by the cross-linking. Such a uniformly dispersed ceramic compound may be advantageous for improving the mechanical strength and ionic conductivity of the polymer solid electrolyte.

[0108] The ceramic compound may also be in the form of particles. Due to its particle morphology, the ceramic compound may be contained in a more uniformly dispersed state within the polymer solid electrolyte. The ceramic compound particles may be spherical and may have a diameter of 100 nm to 1000 nm. If the diameter is less than 100 nm, the amorphization effect due to reduced crystallinity of the polymer may be minimal. If the diameter is more than 1000 nm, the dispersibility may be reduced due to increased aggregation between particles, making uniform dispersion difficult.

[0109] The ceramic compound may be an oxide-based or phosphate-based compound, for example, an oxide-based solid electrolyte in the form of lithium metal oxide or lithium metal phosphate. More specifically, the ceramic compound may be a garnet-type lithium-lanthanum-zirconium oxide (LLZO, Li7La3Zr2O 12 ) compounds, perovskite-type lithium-lanthanum-titanium oxide system (LLTO, Li3xLa 2 / 3-x TiO3) compounds, phosphate-based NASICON-type lithium-aluminum-titanium phosphate (LATP, Li 1+x Al x Ti 2-x (PO4)3) compounds, lithium-aluminum-germanium phosphate system (LAGP, Li 1.5 Al 0.5 Ge 1.5The solid electrolyte may be at least one selected from the group consisting of lithium-lanthanum-zirconium oxide (LLZO), lithium-silicon-titanium phosphate (LSTP, LiSiOTiO(PO)), and lithium-lanthanum-zirconium-titanium oxide (LLZTO). More preferably, the solid electrolyte may be at least one selected from the group consisting of lithium-lanthanum-zirconium oxide (LLZO), lithium-silicon-titanium phosphate (LSTP), lithium-lanthanum-titanium oxide (LLTO), lithium-aluminum-titanium phosphate (LATP), lithium-aluminum-germanium phosphate (LAGP), and lithium-lanthanum-zirconium-titanium oxide (LLZTO).

[0110] The oxide-based or phosphate-based oxide-based solid electrolyte generally has a maximum resistance of 10 -4 ~10 -3 It has the advantages of having an ionic conductivity of 1000 S / cm, being stable in a high voltage range, being stable in air, and being easy to synthesize and handle. Therefore, when the above-mentioned polymer solid electrolyte further contains the ceramic compound, it can compensate for the disadvantages of the remaining polymer components.

[0111] In addition, the ceramic compound has high high-temperature stability because it does not easily burn or ignite even at high temperatures of 400° C. or higher. Therefore, when the polymer solid electrolyte contains the ceramic compound, it is possible to improve the mechanical strength of the polymer solid electrolyte as well as its high-temperature stability and ionic conductivity.

[0112] The ceramic compound may be included in an amount of 10 to 100 parts by weight, or 10 to 60 parts by weight, based on 100 parts by weight of the PEO-based copolymer containing a cross-linkable functional group.

[0113] If the ceramic compound is contained in an excessively small amount, the polymer crystallinity and amorphous effect of the ceramic compound may be reduced, resulting in a small increase in the ionic conductivity of the polymer solid electrolyte, and the mechanical properties may not reach the expected level due to the formation of a composite.

[0114] If the ceramic compound is contained in an excessively large amount, the ceramic compound may not be uniformly dispersed in the polymer, causing the ceramic compound particles to aggregate together, resulting in a polymer solid electrolyte having reduced ionic conductivity.

[0115] Method for producing polymer solid electrolyte The method for preparing the polymer solid electrolyte may include the steps of: (S1) preparing a polymer by crosslinking a polyethylene oxide (PEO) copolymer containing a crosslinkable functional group; and (S2) vapor-depositing a polar solvent onto the polymer prepared in the step (S1).

[0116] The polymer obtained by crosslinking the PEO copolymer containing the crosslinkable functional group has been described above.

[0117] Each step will be explained in more detail below.

[0118] In the step (S1), a polymer can be prepared by cross-linking a PEO (polyethylene oxide) copolymer containing a cross-linkable functional group.

[0119] The cross-linking in step (S1) may be carried out in the presence of one or more additional agents selected from the group consisting of a cross-linking agent and an initiator.

[0120] In addition, to form the polymer solid electrolyte, a lithium salt may be added during or before the cross-linking step (S1), and a ceramic compound may be added.

[0121] The crosslinking may be formed during the drying process after a polymer solution containing the PEO copolymer is applied to a substrate to form a coating film.

[0122] Specifically, the polymer solution may be prepared by mixing the PEO-based copolymer in a solvent, and further mixing a crosslinking agent, an initiator, and / or a lithium salt together.

[0123] The solvent may be any solvent that can be mixed with the PEO copolymer, crosslinker, initiator, and / or lithium salt and can be easily removed by a drying process. For example, the solvent may be acetonitrile, methanol, ethanol, tetrahydrofuran, water, isopropyl alcohol, dimethyl sulfoxide (DMSO), N-methyl-2-pyrrolidone (NMP), or N,N-dimethyl formamide (DMF). These solvents are reaction media for forming crosslinks and are distinct from polar solvents contained in liquid electrolytes. They are completely removed by drying after crosslinking.

[0124] The concentration of the polymer solution can be appropriately adjusted to ensure smooth execution of the molding process for preparing the polymer solid electrolyte. Specifically, the concentration of the polymer solution may refer to the concentration (w / w%) of the polymer in the polymer solution. The concentration of the polymer may refer to the concentration of the PEO-based copolymer. For example, the concentration of the polymer solution may be 5 wt% to 20 wt%, specifically, 5 wt% or more, 7 wt% or more, or 9 wt% or more, or 13 wt% or less, 17 wt% or less, or 20 wt% or less. If the concentration of the polymer solution is less than 5 wt%, the concentration may be too dilute, resulting in a decrease in the mechanical strength of the polymer solid electrolyte or the polymer solid electrolyte may flow when applied to a substrate. If the concentration is more than 20 wt%, it may be difficult to dissolve the lithium salt in the polymer solution to the desired concentration, or the solubility may decrease due to high viscosity, making it difficult to apply the solution to a uniform thin film.

[0125] The substrate is not particularly limited as long as it can serve as a support for the coating film. For example, the substrate may be SUS (stainless steel), polyethylene terephthalate film, polytetrafluoroethylene film, polyethylene film, polypropylene film, polybutene film, polybutadiene film, vinyl chloride copolymer film, polyurethane film, ethylene-vinyl acetate film, ethylene-propylene copolymer film, ethylene-ethyl acrylate copolymer film, ethylene-methyl acrylate copolymer film, or polyimide film.

[0126] The coating method is not particularly limited as long as it can form a coating film by coating the polymer solution on the substrate, and may be, for example, bar coating, roll coating, spin coating, slit coating, die coating, blade coating, comma coating, slot die coating, lip coating, spray coating, or solution casting.

[0127] The coating film formed on the substrate by the above coating method may be formed into a film-shaped polymer from which the residual solvent has been completely removed through a drying process. The drying may be divided into a primary drying process and a secondary drying process to prevent shrinkage of the polymer due to rapid evaporation of the solvent. The primary drying process may remove a portion of the solvent through room temperature drying, and the secondary drying process may completely remove the solvent through high-temperature vacuum drying. The high-temperature drying may be performed at a temperature of 80°C to 130°C. If the high-temperature drying temperature is less than 80°C, the residual solvent may not be completely removed, and if it exceeds 130°C, the polymer may shrink, making it difficult to form a uniform electrolyte membrane.

[0128] The crosslinking agent may form a bond with the crosslinkable functional group. The type of the crosslinking agent, the content of the crosslinking agent, and the type of bond with the crosslinkable functional group are as described above.

[0129] In addition, the initiator may induce a radical polymerization reaction between the cross-linkable functional groups to form cross-links between the cross-linkable functional groups. The functional group that enables the radical polymerization reaction may be a functional group containing vinyl at its terminal, such as an allyl group.

[0130] The initiator is not particularly limited as long as it is an initiator that can induce a radical polymerization reaction between the cross-linking functional groups. For example, the initiator may include one or more selected from the group consisting of benzoyl peroxide, azobisisobutyronitrile, lauroyl peroxide, cumene hydroperoxide, diisopropylphenyl hydroperoxide, tert-butyl hydroperoxide, paramethane hydroperoxide (p-methyl hydroperoxide), and 2,2'-azobis(2-methylpropionitrile).

[0131] The initiator may be used in an amount of 0.5 to 2 parts by weight per 100 parts by weight of the PEO-based copolymer containing cross-linkable functional groups. When used in this range, the initiator can induce a radical polymerization reaction between the cross-linkable functional groups, thereby enabling efficient formation of cross-links.

[0132] The content and type of the lithium salt are as described above.

[0133] Furthermore, the oxide-based solid electrolyte described above can be used as the ceramic compound, and the content thereof is also as described above.

[0134] In step (S2), a polar solvent may be vapor-deposited on the polymer prepared in step (S1) to prepare the polymer solid electrolyte of the embodiment described above. In this case, the gas molecules of the polar solvent may be a polar compound according to the embodiment.

[0135] The vapor deposition may be performed by contacting the vapor of the polar solvent generated by heating or at room temperature with the polymer and allowing it to penetrate into the polymer. In this way, through vapor deposition at room temperature or by heating, the gaseous polar compound may be uniformly diffused on the surface and / or inside of the polymer, and the polar compound gas molecules may be bound to the polymer chains or may be contained in the internal space of the polymer chains in a uniformly dispersed or diffused form.

[0136] When the polar solvent is placed at room temperature during vapor deposition, a small amount of the polar solvent with a low boiling point gradually vaporizes at room temperature and penetrates into the polymer, effectively inducing a change in the conformation of the polymer chains cross-linked within the polymer.

[0137] Furthermore, heating the polar solvent during vapor deposition can increase the vapor deposition rate. The heating temperature is not particularly limited as long as it is a temperature at which the polar solvent can change phase to vapor, and may be, for example, 30°C to 80°C. While typical PEO melts at 60°C, the PEO copolymer modified with cross-linking functional groups exhibits improved heat resistance and can withstand temperatures up to 80°C when a cross-linked structure is formed, thereby further increasing the vapor deposition rate. The heating method can be any method capable of supplying energy to generate vapor. Examples of suitable methods include, but are not limited to, direct heating using a burner or stove, and indirect heating using a heater or steam tube.

[0138] If the heating temperature is too high, the polar solvent may boil above its boiling point, or the solvent may undergo structural changes, or polymer deformation may be induced. Furthermore, it may be difficult to control the evaporation rate of the polar solvent during vapor deposition. Therefore, in order to vapor deposit a small amount of polar solvent, it may be preferable to perform vapor deposition at a heating temperature within the appropriate range as specified above.

[0139] All solid state battery Another embodiment of the present invention relates to an all-solid-state battery further including the polymer solid electrolyte. The all-solid-state battery includes an anode, a cathode, and a polymer solid electrolyte interposed between the anode and the cathode, and the polymer solid electrolyte is according to any of the above-described embodiments.

[0140] Specifically, the polymer solid electrolyte includes a polymer in which a polyethylene oxide (PEO) copolymer containing a cross-linkable functional group is cross-linked, a gaseous polar compound, and optionally a ceramic compound. The gaseous polar compound is contained in or bonded to the polymer solid electrolyte, thereby improving ionic conductivity, and therefore the polymer solid electrolyte may be suitable as an electrolyte for an all-solid-state battery.

[0141] Meanwhile, the positive electrode included in the all-solid-state battery may include a positive electrode active material layer, and the positive electrode active material layer may be formed on one surface of a positive electrode current collector.

[0142] The positive electrode active material layer includes a positive electrode active material, a binder, and a conductive material.

[0143] The positive electrode active material is not particularly limited as long as it is a material capable of reversibly inserting and releasing lithium ions, and examples thereof include lithium cobalt oxide, lithium nickel oxide, Li[NixCoyMnzMv]O2 (wherein M is one or more elements selected from the group consisting of Al, Ga, and In, and 0.3≦x<1.0, 0≦y, z≦0.5, 0≦v≦0.1, and x+y+z+v=1), Li(LiaMb-a-b'M'b')O 2-cA c (wherein 0≦a≦0.2, 0.6≦b≦1, 0≦b′≦0.2, 0≦c≦0.2, M comprises Mn and one or more elements selected from the group consisting of Ni, Co, Fe, Cr, V, Cu, Zn, and Ti; M′ is one or more elements selected from the group consisting of Al, Mg, and B; and A is one or more elements selected from the group consisting of P, F, S, and N), and compounds substituted with one or more transition metals; 1+y Mn 2-y Lithium manganese oxides such as LiMnO4 (where y is 0 to 0.33), LiMnO3, LiMn2O3, and LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, LiFe3O4, V2O5, and Cu2V2O7; 1-y Ni-site lithium nickel oxide represented by MyO2 (where M=Co, Mn, Al, Cu, Fe, Mg, B, or Ga, and y=0.01 to 0.3); chemical formula LiMn 2-y M y Examples of suitable lithium manganese composite oxides include, but are not limited to, lithium manganese composite oxides represented by Li2Mn3MO8 (where M is Co, Ni, Fe, Cr, Zn, or Ta, and y is 0.01 to 0.1) or Li2Mn3MO8 (where M is Fe, Co, Ni, Cu, or Zn); LiMn2O4, in which part of the Li in the chemical formula is substituted with an alkaline earth metal ion; disulfide compounds; and Fe2(MoO4)3.

[0144] The positive electrode active material may be included in an amount of 40 to 80 wt % based on the total weight of the positive electrode active material layer. Specifically, the content of the positive electrode active material may be 40 wt % or more, or 50 wt % or more, or 70 wt % or less, or 80 wt % or less. If the content of the positive electrode active material is less than 40 wt %, the connectivity between the positive electrode active materials and the electrical properties may be insufficient, and if it exceeds 80 wt %, the mass transfer resistance may be increased.

[0145] The binder is a component that aids in bonding the positive electrode active material to the conductive material and the current collector, and is selected from the group consisting of styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile copolymer, acrylonitrile-butadiene rubber, nitrile butadiene rubber, acrylonitrile-styrene-butadiene copolymer, acrylic rubber, butyl rubber, fluorine rubber, polytetrafluoroethylene, polyethylene, polypropylene, ethylene / propylene copolymer, polybutadiene, polyethylene oxide, chlorosulfonated polyethylene, polyvinylpyrrolidone, polyvinylpyridine, polyvinyl alcohol, polyvinyl acetate, polyepichlorohydrin, polyphosphazene, polyacrylic The binder may include one or more selected from the group consisting of styrene-butadiene rubber, polytetrafluoroethylene, carboxymethyl cellulose, polystyrene, latex, acrylic resin, phenolic resin, epoxy resin, carboxymethyl cellulose, hydroxypropyl cellulose, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl cellulose, cyanoethyl sucrose, polyester, polyamide, polyether, polyimide, polycarboxylate, polycarboxylic acid, polyacrylic acid, polyacrylate, lithium polyacrylate, polymethacrylic acid, polymethacrylate, polyacrylamide, polyurethane, polyvinylidene fluoride, and poly(vinylidene fluoride)-hexafluoropropene. Preferably, the binder may include one or more selected from the group consisting of styrene-butadiene rubber, polytetrafluoroethylene, carboxymethyl cellulose, polyacrylic acid, lithium polyacrylate, and polyvinylidene fluoride.

[0146] The binder may be included in an amount of 1 wt % to 30 wt % based on the total weight of the positive electrode active material layer. Specifically, the binder content may be 1 wt % or more or 3 wt % or more, and 15 wt % or less or 30 wt % or less. If the binder content is less than 1 wt %, the adhesive strength between the positive electrode active material and the positive electrode current collector may be reduced. If the binder content exceeds 30 wt %, the adhesive strength is improved, but the content of the positive electrode active material may be reduced accordingly, resulting in a reduced battery capacity.

[0147] Furthermore, the conductive material is not particularly limited as long as it prevents side reactions in the internal environment of the all-solid-state battery, does not induce chemical changes in the battery, and has excellent electrical conductivity. Representative examples include graphite or conductive carbon. Examples include graphite such as natural graphite and artificial graphite; carbon black such as carbon black, acetylene black, ketjen black, denka black, thermal black, channel black, furnace black, and lamp black; carbon-based substances having a graphene or graphite crystal structure; conductive fibers such as carbon fibers and metal fibers; carbon fluoride; metal powders such as aluminum powder and nickel powder; conductive whiskey such as zinc oxide and potassium titanate; conductive oxides such as titanium oxide; and conductive polymers such as polyphenylene derivatives. These may be used alone or in combination of two or more, but are not necessarily limited thereto.

[0148] The conductive material may typically be included in an amount of 0.5 wt % to 30 wt % based on the total weight of the positive electrode active material layer. Specifically, the content of the conductive material may be 0.5 wt % or more, or 1 wt % or more, or 20 wt % or less, or 30 wt % or less. If the content of the conductive material is too low, such as less than 0.5 wt %, the electrical conductivity improvement effect may be difficult to expect or the electrochemical characteristics of the battery may be degraded. If the content is too high, such as more than 30 wt %, the amount of positive electrode active material may be relatively reduced, resulting in reduced capacity and energy density. The method for incorporating the conductive material into the positive electrode is not particularly limited, and conventional methods known in the art, such as coating the positive electrode active material, may be used.

[0149] The positive electrode current collector supports the positive electrode active material layer and plays a role in transferring electrons between an external conductor and the positive electrode active material layer.

[0150] The positive electrode current collector is not particularly limited as long as it does not induce chemical changes in the all-solid-state battery and has high electronic conductivity. For example, the positive electrode current collector may be made of copper, stainless steel, aluminum, nickel, titanium, palladium, baked carbon, copper or stainless steel surface-treated with carbon, nickel, silver, or the like, or an aluminum-cadmium alloy.

[0151] The positive electrode current collector may have a micro-irregular structure or a three-dimensional porous structure on its surface to strengthen the bonding strength with the positive electrode active material layer, and may have various forms such as a film, sheet, foil, mesh, net, porous body, foam, or nonwoven fabric.

[0152] The positive electrode may be fabricated by a conventional method. Specifically, the positive electrode active material, conductive material, and binder are mixed in an organic solvent to form a positive electrode active material layer. The resulting composition is then applied to a positive electrode current collector, dried, and optionally compression-molded into a current collector to improve electrode density. The organic solvent is preferably one that can uniformly disperse the positive electrode active material, binder, and conductive material and is easily evaporated. Specific examples of the organic solvent include acetonitrile, methanol, ethanol, tetrahydrofuran, water, isopropyl alcohol, dimethyl sulfoxide (DMSO), and N-methyl-2-pyrrolidone (NMP).

[0153] Meanwhile, the negative electrode included in the all-solid-state battery may include a negative electrode active material layer, and the negative electrode active material layer may be formed on one surface of a negative electrode current collector.

[0154] The negative electrode active material may include a material capable of reversibly intercalating or deintercalating lithium (Li+), a material capable of reversibly forming a lithium-containing compound by reacting with lithium ions, lithium metal, or a lithium alloy.

[0155] The material capable of reversibly inserting or de-inserting lithium ions (Li+) may be, for example, crystalline carbon, amorphous carbon, or a mixture thereof. The material capable of reacting with lithium ions (Li+) to reversibly form a lithium-containing compound may be, for example, tin oxide, titanium nitrate, or silicon. The lithium alloy may be, for example, an alloy of lithium (Li) and a metal selected from the group consisting of sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), francium (Fr), beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), radium (Ra), aluminum (Al), and tin (Sn).

[0156] Preferably, the negative electrode active material may be lithium metal, specifically in the form of a lithium metal thin film or lithium metal powder.

[0157] The negative electrode active material may be included in an amount of 40 to 80 wt % based on the total weight of the negative electrode active material layer. Specifically, the content of the negative electrode active material may be 40 wt % or more, or 50 wt % or more, or 70 wt % or less, or 80 wt % or less. If the content of the negative electrode active material is less than 40 wt %, the electrical properties may be insufficient, and if it exceeds 80 wt %, the mass transfer resistance may be high.

[0158] The binder is the same as that described above in the positive electrode active material layer.

[0159] The conductive material is the same as that described above in the positive electrode active material layer.

[0160] The negative electrode current collector is not particularly limited as long as it is conductive and does not induce chemical changes in the battery, and examples of the negative electrode current collector that can be used include copper, stainless steel, aluminum, nickel, titanium, baked carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., aluminum-cadmium alloy, etc. Similarly to the positive electrode current collector, the negative electrode current collector can be in various forms such as a film, sheet, foil, net, porous material, foam, nonwoven fabric, etc., with fine irregularities formed on the surface.

[0161] The method for manufacturing the negative electrode is not particularly limited, and the negative electrode may be manufactured by forming a negative electrode active material layer on a negative electrode current collector using a layer or film formation method commonly used in the art. For example, methods such as compression bonding, coating, and vapor deposition may be used. Furthermore, the negative electrode of the present invention also includes a battery in which a thin lithium film is formed on the metal plate by initial charging after assembling the battery without a thin lithium film on the negative electrode current collector.

[0162] Meanwhile, according to additional embodiments of the present invention, there are provided a battery module including the all-solid-state battery as a unit cell, a battery pack including the battery module, and a device including the battery pack as a power source.

[0163] Specific examples of the device include, but are not limited to, power tools driven by electric motors; electric vehicles including electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs); electric two-wheeled vehicles including electric bicycles (E-bikes) and electric scooters; electric golf carts; and power storage systems.

[0164] Preferred examples are presented below to aid in understanding the present invention. However, the following examples are provided only to facilitate understanding of the invention, and the present invention is not limited thereto.

[0165] [Example] Example 1: Preparation of polymer solid electrolyte Step 1) Preparation of polymers including copolymers A polyethylene oxide (PEO) copolymer of the following formula 1a was prepared.

[0166] [ka]

[0167] In the above formula 1a, R1 is -CH2-O-(CH2-CH2-O) k The copolymer of formula 1a has an allyl group linked via a methylene oxide linker as a crosslinkable functional group.

[0168] The polyethylene oxide copolymer was mixed with trimethylolpropane trimethacrylate as a crosslinker, benzoyl peroxide as an initiator, and LiTFSI as a lithium salt in acetonitrile as a solvent to prepare a polymer solution, which was then stirred for 24 hours using a magnetic bar. The polymer solution was prepared by mixing 20 parts by weight of trimethylolpropane trimethacrylate as a crosslinker, 1 part by weight of benzoyl peroxide as an initiator, and 36.5 parts by weight of the lithium salt with 100 parts by weight of the polyethylene oxide copolymer, and the acetonitrile solvent was used so that the concentration of the polyethylene oxide copolymer as a polymer in the polymer solution was 10.4 wt%.

[0169] The prepared polymer solution was solution-cast onto the lower substrate of a coin cell, and then primarily dried at room temperature for 12 hours, followed by secondary drying at 100°C for 12 hours to induce cross-linking, thereby fabricating an electrolyte film with a thickness of 200 μm.

[0170] 2nd step) Preparation of polymer solid electrolyte The polymer was attached to the upper plate of a chamber, and the lower part of the chamber was filled with EMC solvent, which was then allowed to evaporate naturally at room temperature for 72 hours. EMC vapor was then introduced into the polymer attached to the upper part of the chamber and deposited on the polymer, producing a polymer solid electrolyte.

[0171] Example 2: Preparation of composite solid electrolyte In step 1) of Example 1, a composite solid electrolyte was prepared in the same manner as in Example 1, except that a mixed solution was prepared by mixing 20 parts by weight of trimethylolpropane trimethacrylate as a crosslinker, 1 part by weight of benzoyl peroxide as an initiator, 36 parts by weight of a lithium salt, and 40 parts by weight of LSTP as a ceramic compound with 100 parts by weight of polyethylene oxide copolymer, and an acetonitrile solvent was used so that the concentration of the polyethylene oxide copolymer as a polymer contained in the mixed solution was 11.1 wt %, and the concentrations of the polyethylene oxide copolymer as a polymer and the ceramic compound were 14.9 wt %.

[0172] Comparative Example Comparative Example 1: Modified PEO + Polymer Solid Electrolyte with Large Amount of Liquid A polymer solid electrolyte was prepared in the same manner as in Example 1, except that EMC solvent (12 wt%) was directly injected in a liquid state into the polymer solid electrolyte prepared in step 1) of Example 1.

[0173] Comparative Example 2: Modified PEO + Composite Solid Electrolyte with Large Amount of Liquid A composite solid electrolyte was prepared in the same manner as in Example 2, except that EMC solvent (12 wt%) was directly injected in a liquid state into the composite solid electrolyte prepared in step 1) of Example 2.

[0174] Experimental Example Experimental Example 1: Confirmation of the correlation between the behavior of polar solvents and polymers during vapor deposition and ionic conductivity Using the following equation 1 or 2, the correlation between the behavior of polar solvents (polar compounds) and polymers during vapor deposition and ionic conductivity was confirmed.

[0175]

number

[0176] In the above equation 1, t R is the relaxation time of the polymer chain, t D is the diffusion time of the polar compound within the polymer chain, which may be calculated by Equation 2 below:

[0177]

number

[0178] In the above equation 2, D is the diffusion coefficient of the polar compound within the polymer chain, and is 10 -9 or 10 -6 cm 2 / s, calculated by the following formula 3, where L is the thickness of the polymer solid electrolyte, which is 5 to 500 μm.

[0179]

number

[0180] M(t) is the evaporation rate of the polar compound contained in the polymer solid electrolyte, and M∞ is the maximum or saturated value of the polar compound that can be contained in the polymer solid electrolyte and is 0.005 to 0.5; L is the thickness of the polymer solid electrolyte and is 5 μm to 500 μm; and t is the time at which the evaporation rate of the polar compound is measured.

[0181] (1)t R / t D Calculating values In Equation 3, the evaporation rate M(t), which indicates the amount of evaporation of the polar compound over time, was calculated using the weight change rate after measuring the weight of the polar compound contained in the polymer solid electrolyte prepared in the Examples and Comparative Examples before and after evaporation. The calculated polar solvent evaporation rate (M(t)) was applied to Equation 1 to obtain the fitting parameter M ∞ The values ​​of D and D were then derived. The derived D values ​​were then applied to Equation 2 to obtain t D The value of t D Applying the value to Equation 1 above, t R / t D The value was calculated.

[0182] (2) Measurement of ionic conductivity The ionic conductivity of the polymer solid electrolyte was calculated using the following equation 4.

[0183] To measure the ionic conductivity of the polymer solid electrolytes prepared in the examples and comparative examples, a 1.7671 cm 2 The solid polymer electrolyte was formed on the lower substrate of a coin cell of the same size, and then SUS was used as an inert electrode (blocking electrode) to prepare a coin cell for measuring ionic conductivity.

[0184] Resistance was measured using an electrochemical impedance spectrometer (EIS, VM3, Bio Logic Science Instrument) at 25°C under conditions of an amplitude of 10 mV and a scan range of 1 Hz to 0.1 MHz, and the ionic conductivity of the polymer solid electrolyte was calculated using the following Equation 2:

[0185]

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[0186] In the above equation 4, σ i is the ionic conductivity (S / cm) of the polymer solid electrolyte, R is the resistance (Ω) of the solid electrolyte measured by the electrochemical impedance spectrometer, L is the thickness (μm) of the polymer solid electrolyte, and A is the area (cm 2 The solid polymer electrolyte sample had an L of 200 μm and an A of 1.7671 cm 2 is.

[0187] Table 1 below shows the t calculated by Equation 1. R / t D The results of calculating the ionic conductivity and the ionic conductivity are shown.

[0188] [Table 1]

[0189] As shown in Table 1, the t R / t D It was confirmed that the ionic conductivity and ionic conductivity values ​​were significantly higher than those of Comparative Example 1. Example 1 is a polymer solid electrolyte prepared by the solvent vapor deposition method. R It was confirmed that the relative increase in ionic conductivity resulted in improved ionic conductivity.

Claims

1. The polymer includes a PEO (polyethylene oxide) copolymer containing a cross-linkable functional group, and a polar compound; at least a part of the cross-linking functional groups form cross-links with each other, and the polymer forms a three-dimensional network structure; The polar compound is contained in the three-dimensional network structure in a gaseous state or is bonded to the polymer chain of the polymer, and the polymer solid electrolyte satisfies the following formula 1: [Equation 1] In the above equation 1, t Ｒ is the relaxation time of the polymer chain, t Ｄ is the diffusion time of the polar compound within the polymer chain, and is defined by the following Equation 2: [Equation 2] In the above equation 2, D is the diffusion coefficient of the polar compound within the polymer chain, and －９ cm ２ / s to 10 －６ cm ２ / s, and L is the thickness of the polymer solid electrolyte, which is 5 μm to 500 μm.

2. 2. The polymer solid electrolyte according to claim 1, wherein the gaseous polar compound is dispersed among the polymer chains forming the three-dimensional network structure, or is adsorbed or bonded to the surface or inside of the polymer chains.

3. The polymer solid electrolyte according to claim 1 , further comprising a cross-linking agent, and at least some of the cross-linkable functional groups form cross-links with each other via the cross-linking agent.

4. the cross-linking functional group is bonded to the PEO-based copolymer via an alkylene linker or alkylene oxide linker having 0 to 10 carbon atoms (wherein an alkylene linker having 0 carbon atoms represents a single bond); A polymer solid electrolyte selected from the group consisting of a hydroxyl group, a carboxyl group, an isocyanate group, a nitro group, a cyano group, an amine group, an amide group, an epoxy group, and an allyl group.

5. The polymer solid electrolyte according to claim 1 , further comprising a lithium salt dispersed on the polymer forming the three-dimensional network structure.

6. The polymer solid electrolyte according to claim 1 , wherein the PEO (polyethylene oxide) copolymer is a copolymer including repeating units of the following formulas 1 to 3: 【Chemical 1】 In the above formulas 1 to 3, R １ is -CH ２ -O-(CH ２ -CH ２ -O) ｋ -R ３ where k is 0 to 20, and R ３ represents an alkyl group having 1 to 5 carbon atoms, R ２ represents a substituent in which one or more crosslinkable functional groups selected from the group consisting of a hydroxyl group, a carboxyl group, an isocyanate group, a nitro group, a cyano group, an amine group, an amide group, an epoxy group, and an allyl group are bonded to a polymer chain via an alkylene linker or alkylene oxide linker having 0 to 10 carbon atoms (provided that an alkylene linker having 0 carbon atoms represents a single bond), l, m, and n are the number of repeats of the repeating unit, l and n are each independently an integer of 1 to 1,000, and m is an integer of 0 to 1,000.

7. 2. The polymer solid electrolyte according to claim 1, wherein the content of the polar compound is 0.1 wt % or more and less than 10 wt % based on the total weight of the polymer solid electrolyte.

8. The polymer solid electrolyte according to claim 1 , wherein the polar compound comprises at least one selected from the group consisting of carbonate-based compounds and sulfonyl-based compounds.

9. 10. The polymer solid electrolyte of claim 1, further comprising a ceramic compound dispersed within the three-dimensional network structure of the polymer.

10. The polymer solid electrolyte according to claim 9 , wherein the ceramic compound comprises an oxide-based solid electrolyte of lithium metal oxide or lithium metal phosphate.

11. 10. The polymer solid electrolyte of claim 9, wherein the ceramic compound comprises one or more oxide-based solid electrolytes selected from the group consisting of lithium-lanthanum-zirconium oxide (LLZO) compounds, lithium-silicon titanium phosphate (LSTP) compounds, lithium-lanthanum-titanium oxide (LLTO) compounds, lithium-aluminum-titanium phosphate (LATP) compounds, lithium-aluminum-germanium phosphate (LAGP) compounds, and lithium-lanthanum-zirconium-titanium oxide (LLZTO) compounds.

12. 12. An all-solid-state battery comprising: a positive electrode; a negative electrode; and an electrolyte layer interposed between the positive electrode and the negative electrode and comprising the polymer solid electrolyte according to claim 1.

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