Polymer solid electrolyte composition and use thereof

Abstract

The invention relates to a polymer solid electrolyte composition and application thereof. The conductivity of the polymer solid electrolyte can be improved. In addition, when the present invention is used in a lithium metal battery including an anode having a specific composition, the battery resistance can be reduced.

Description

Technical Field

[0001] The present invention relates to a polymer solid electrolyte composition and its use.

[0002] Specifically, the present invention relates to a polymer solid electrolyte composition, a polymer solid electrolyte, and a lithium secondary battery. Background Art

[0003] The demand for secondary batteries is increasing in various fields such as PCs, mobile phones, electric vehicles, and energy storage devices. Among secondary batteries, lithium secondary batteries in particular have a higher capacity density than other secondary batteries and operate at high voltages.

[0004] A lithium secondary battery generally consists of an anode, a cathode, and an electrolyte containing a lithium salt interposed between the anode and the cathode. This electrolyte is a non-aqueous liquid electrolyte or a solid electrolyte. The non-aqueous liquid electrolyte penetrates into the interior of the anode. Therefore, the non-aqueous liquid electrolyte can easily form an interface between the active material of the anode and the electrolyte to impart high electrical performance.

[0005] However, since the non-aqueous liquid electrolyte uses a flammable organic solvent, it is prone to catching fire due to overcurrent caused by a short circuit, etc. Therefore, the non-aqueous liquid electrolyte requires a separate safety device, selection of special battery materials, etc., and limits the battery structure design. This is the reason for the increase in the manufacturing cost and the decrease in the productivity of lithium secondary batteries.

[0006] All-solid-state batteries use a solid electrolyte instead of a liquid electrolyte. All-solid-state batteries do not have the disadvantages caused by the use of flammable organic solvents. Therefore, all-solid-state batteries have the advantages of low manufacturing cost and excellent productivity. In addition, all-solid-state batteries have a simple structure. Therefore, the advantages brought by the structure of all-solid-state batteries are excellent stability and high capacity and output.

[0007] The types of solid electrolytes include sulfide solid electrolytes, oxide solid electrolytes, polymer solid electrolytes, etc. Sulfide solid electrolytes and oxide solid electrolytes must be compressed at high temperature and high pressure due to their high interfacial resistance. Polymer solid electrolytes can be manufactured under normal conditions (room temperature and atmospheric pressure), which is advantageous.

[0008] However, the disadvantage of polymer solid electrolytes is insufficient conductivity.

[0009] Patent Document 1 discloses the following: a structure formed by combining synthesized polyethylene glycol (PEG) with poly(aryl ether sulfone) (PAES) and poly(aryl ether ketone) (PAEK) respectively, and using THF solvent to fabricate it into an electrolyte membrane. In terms of the technology of Patent Document 1, the interfacial resistance between the electrolyte membrane and the electrode is high. In addition, since Patent Document 1 uses a solvent to manufacture the polymer electrolyte, it is difficult to directly form the electrolyte membrane on the electrode.

[0010] Non-Patent Document 1 describes the RAFT polymerization of PEGMA and PEGDA on the electrode. Non-Patent Document 2 describes a polymer solid electrolyte fabricated by polymerizing PEGMEM, PEGMA, and POSS. However, the technologies of Non-Patent Document 1 and Non-Patent Document 2 are insufficient in terms of the ionic conductivity of the polymer solid electrolyte and the lifespan of the battery fabricated therefrom.

[0011] [Prior Art Documents]

[0012] [Patent Documents]

[0013] (Patent Document 1) Published Patent Gazette No. 10-2022-0039180 (March 29, 2022)

[0014] [Non-Patent Documents]

[0015] (Non-Patent Document 1) Ji Hu, “Poly(ethylene oxide)-based composite polymer electrolytes embedding with ionic bond modified nanoparticles for all-solid-state lithium-ion battery”, (2019) 200

[0016] (Non-Patent Document 2) Jinfang Zhang, “A star-shaped solid composite electrolyte containing multifunctional moieties with enhanced electrochemical properties for all solid-state lithium batteries”, (2018) 107 Summary of the Invention

[0017] Technical problem

[0018] The present invention aims to improve the conductivity of a polymer solid electrolyte.

[0019] The present invention aims to improve the lifespan of a lithium secondary battery.

[0020] Method for solving the problem

[0021] The polymer solid electrolyte composition of the present invention comprises a first liquid and a second liquid. The first liquid comprises a polyalkylene glycol (meth)acrylate, an ethylene carbonate alkylene ester, and a polyfunctional (meth)acrylate. The second liquid comprises a nitrile compound represented by Chemical Formula 1:

[0022] [Chemical Formula 1]

[0023] CN-X-CN

[0024] In Chemical Formula 1, X is a substituted or unsubstituted linear or branched alkylene having 1 to 20 carbon atoms.

[0025] The polymer solid electrolyte of the present invention comprises a polymer matrix and a dispersed monomer. The polymer matrix comprises a polymerization unit derived from a polyalkylene glycol (meth)acrylate, a polymerization unit derived from an ethylene carbonate alkylene ester, and a polymerization unit derived from a polyfunctional (meth)acrylate. The dispersed monomer is dispersed in the polymer matrix and comprises a nitrile compound represented by Chemical Formula 1:

[0026] [Chemical Formula 1]

[0027] CN-X-CN

[0028] In Chemical Formula 1, X is a substituted or unsubstituted linear or branched alkylene having 1 to 20 carbon atoms.

[0029] The lithium secondary battery of the present invention comprises: a solid electrolyte layer containing a polymer solid electrolyte; an anode layer on one side of the solid electrolyte layer; and a cathode layer on the opposite side of the anode layer with respect to the solid electrolyte layer.

[0030] Advantageous effects of the invention

[0031] The present invention can improve the conductivity of a polymer solid electrolyte.

[0032] The present invention can improve the lifespan of a lithium secondary battery. Description of the drawings

[0033] Figure 1 It is a schematic diagram of the polymer solid electrolyte of the present invention.

[0034] Figure 2It is the SEM photograph of the electrode-electrolyte interface fabricated in Example 1. Detailed Description of the Invention

[0035] Polymer Solid Electrolyte Composition

[0036] One aspect of the present invention is a polymer solid electrolyte composition. If the composition of the present invention is dried, a polymer solid electrolyte can be obtained.

[0037] The composition of the present invention is a two-liquid type composition. Among them, when forming a polymer solid electrolyte, one liquid becomes a matrix, and the remaining one liquid becomes a phase dispersed in the matrix. Hereinafter, the former is referred to as the first liquid, and the latter is referred to as the second liquid. In addition, if the phases of the respective substances are liquid at the temperature of fabricating the composition of the present invention, they can be referred to as the first liquid and the second liquid respectively. In other words, the above-mentioned first liquid and second liquid are not necessarily liquid only at normal temperature.

[0038] The first liquid contains a monomer and / or polymer component having a specified composition and other additives, etc. Specifically, the first liquid contains polyalkylene glycol (meth)acrylate and ethylene alkylene carbonate.

[0039] The polyalkylene glycol (meth)acrylate constitutes the central skeleton of the matrix. This matrix enables the polymer solid electrolyte to have a free standing form.

[0040] In particular, the above-mentioned ethylene alkylene carbonate can be introduced into the polymer main chain in the polymer solid electrolyte by polymerizing with the above-mentioned polyalkylene glycol (meth)acrylate. If the above-mentioned ethylene alkylene carbonate is introduced into the main chain of the polymer, the stable performance of the battery can be maintained for a long time. That is, if the above-mentioned ethylene alkylene carbonate is introduced into the polymer main chain in the polymer solid electrolyte, the life of the battery can be extended.

[0041] In the present invention, (meth)acrylate is methacrylate or acrylate.

[0042] In the present invention, alkylene is a linear or branched alkylene having 1 to 20 carbon atoms which may be substituted or unsubstituted.

[0043] In addition to the above components, the first liquid further contains a crosslinking agent. That is, the first liquid contains a substance that can form a crosslinked structure between the polymers formed by the above-mentioned polyalkylene glycol (meth)acrylate and ethylene alkylene carbonate.

[0044] Specifically, the first liquid contains a polyfunctional (meth)acrylate as a crosslinking agent. The polyfunctional (meth)acrylate is a compound having at least two (meth)acryloyl groups. The first liquid can form a solid polymer matrix by containing the polyfunctional (meth)acrylate. The first liquid can produce a polymer solid electrolyte that is closely adhered to the anode when joined to the anode of a specific component by containing the polyfunctional (meth)acrylate. Specifically, the polyfunctional (meth)acrylate in the first liquid can penetrate into the interior of the anode before polymerization. If the monomeric components that penetrate in this way form a crosslinked structure, the adhesion between the polymer solid electrolyte layer and the electrode can be improved. If the polymer solid electrolyte is closely adhered to the electrode, the interfacial resistance between the electrode and the electrolyte is reduced. As a result, the resistance of the battery is lowered.

[0045] The second liquid contains a compound having a specific structure as a monomer and disperses the monomer in the polymer matrix formed by the first liquid. In addition, the monomers thus dispersed can improve the ionic conductivity of the polymer solid electrolyte. The second liquid contains a nitrile compound. Specifically, the second liquid contains a nitrile compound represented by Chemical Formula 1:

[0046] [Chemical Formula 1]

[0047] CN-X-CN

[0048] In Chemical Formula 1, X is a substituted or unsubstituted linear or branched alkylene group having 1 to 20 carbon atoms. Preferably, X is an unsubstituted alkylene group. Preferably, X is a linear alkylene group. Preferably, X is an alkylene group having 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, 1 to 4 carbon atoms, or 1 to 2 carbon atoms. More preferably, X is an ethylene group.

[0049] The types of the above polyalkylene glycol (meth)acrylates are not restrictive, and among known components, components capable of forming the central skeleton structure of the polymer solid electrolyte can be used without limitation. Preferably, the above polyalkylene glycol (meth)acrylate is polyethylene glycol methacrylate.

[0050] The properties of the above polyalkylene glycol (meth)acrylates are also not restrictive. For example, the molecular weight of the above polyalkylene glycol (meth)acrylate can be controlled within a specific range to produce a solid electrolyte membrane. Specifically, the number average molecular weight of the above polyalkylene glycol (meth)acrylate can be in the range of 100 to 1000. The lower limit of the above range can be 200, 300, 400, or 500. The upper limit of the above range can be 900, 800, 700, 600, or 500.

[0051] The first liquid may contain the above-mentioned polyalkylene glycol (meth)acrylate as a main component. The so-called containing a specific component as a main component may mean that the content of this component is 50% by weight or more based on the total weight.

[0052] Therefore, based on the total weight of the above-mentioned first liquid, the content of the above-mentioned polyalkylene glycol (meth)acrylate may be in the range of 50% by weight to 90% by weight. The lower limit (unit: % by weight) of the above range may be 55, 60 or 65. The upper limit (unit: % by weight) of the above range may be 85, 80, 75, 70 or 65. Within the content range of the above-mentioned polyalkylene glycol (meth)acrylate, a polymer solid electrolyte with a solid structure can be manufactured.

[0053] The type of the above-mentioned ethylene carbonate alkylene ester is not restrictive. The above-mentioned ethylene carbonate alkylene ester can be selected from components that can maintain the stable performance of the battery for a long time. Preferably, the above-mentioned ethylene carbonate alkylene ester may be ethylene carbonate ethyl ester.

[0054] The content of the above-mentioned ethylene carbonate alkylene ester can also be appropriately controlled. Relative to 100 parts by weight of the above-mentioned polyalkylene glycol (meth)acrylate, the content of the above-mentioned ethylene carbonate alkylene ester may be in the range of 10 parts by weight to 20 parts by weight. Within the above range, the stable performance of the battery can be appropriately maintained for a long time.

[0055] The type of the above-mentioned polyfunctional (meth)acrylate is not restrictive. The above-mentioned polyfunctional (meth)acrylate can be selected from components having two or more (meth)acryloyl groups and capable of imparting an appropriate cross-linked structure to a polymer containing the above-mentioned polyalkylene glycol (meth)acrylate and ethylene carbonate alkylene ester. Preferably, the above-mentioned polyfunctional (meth)acrylate is polyalkylene glycol di(meth)acrylate. More preferably, the above-mentioned polyfunctional (meth)acrylate is polyethylene glycol diacrylate.

[0056] When using polyalkylene glycol di(meth)acrylate as the above-mentioned polyfunctional (meth)acrylate, its molecular weight can be appropriately controlled to manufacture an electrolyte membrane with sufficient strength. For example, the number average molecular weight of the above-mentioned polyfunctional (meth)acrylate may be in the range of 500 to 1500. The lower limit of the above range may be 550, 600, 650 or 700. The upper limit of the above range may be 1400, 1300, 1200, 1100, 1000, 900, 800 or 700.

[0057] The first liquid may further contain other known components required for generating the polymer solid electrolyte.

[0058] For example, since the above-mentioned first liquid forms a polymer of polyalkylene glycol (meth)acrylate and ethylene alkylene carbonate, a polymerization initiator may also be included.

[0059] The types of the above-mentioned polymerization initiator are not restrictive. The above-mentioned polymerization initiator can be selected from the components that can generally initiate polymerization reactions. For example, the above-mentioned polymerization initiator can be selected from the group consisting of 2,2-azobisisobutyronitrile (AIBN), benzoyl peroxide, acetyl peroxide, lauryl peroxide, tert-butyl peracetate, tert-butyl hydroperoxide, and di-tert-butyl peroxide. Preferably, the above-mentioned polymerization initiator is 2,2-azobisisobutyronitrile.

[0060] The content of the above-mentioned polymerization initiator can also be appropriately controlled. Relative to 100 parts by weight of the above-mentioned polyalkylene glycol (meth)acrylate, the content of the above-mentioned polymerization initiator can be in the range of 0.1 part by weight to 1 part by weight. Within the above range, the polymerization reaction of the components in the above-mentioned first liquid can be appropriately initiated. The lower limit (unit: part by weight) of the above range can be 0.2, 0.3, 0.4, or 0.5. The upper limit (unit: part by weight) of the above range can be 0.9, 0.8, 0.7, 0.6, or 0.5.

[0061] The polymer solid electrolyte composition of the present invention can be used to manufacture a polymer solid electrolyte applied in a lithium secondary battery. Specifically, the polymer solid electrolyte composition of the present invention can be used to manufacture a polymer solid electrolyte applied in a lithium metal battery. Therefore, the above-mentioned polymer solid electrolyte composition, specifically the above-mentioned first liquid, may further contain a lithium salt.

[0062] The above-mentioned lithium salt can be, for example, LiPF6, LiBF4, LiCF3SO3, Li(CF3SO2)2N, Li(CF3SO2)3C, LiC2F5SO3, Li(FSO2)2N, LiC4F9SO3, LiN(SO2CF2CF3)2, LiN(CN)2, etc. Preferably, the lithium salt is Li(CF3SO2)2N.

[0063] The present invention does not limit the content of the lithium salt. The above-mentioned lithium salt can be appropriately added to such an extent that the electrolyte of the present invention exhibits sufficient activity. For example, in the above-mentioned first liquid, the concentration of the above-mentioned lithium salt can be in the range of 0.5 M to 2 M. The lower limit (unit: M) of the above range can be 0.6, 0.7, 0.8, 0.9, or 1.0. The upper limit (unit: M) of the above range can be 1.9, 1.8, 1.7, 1.6, 1.5, 1.4, 1.3, 1.2, 1.1, or 1.0.

[0064] Preferably, the composition of the above-mentioned second liquid is also adjusted.

[0065] As described above, X in Chemical Formula 1 is preferably ethylene. That is, the above nitrile compound is preferably succinonitrile.

[0066] The second liquid may contain the above nitrile compound as a main component. The so-called containing a specific component as a main component may mean that the content of this component is 50% by weight or more based on the total weight.

[0067] Therefore, based on the total weight of the above second liquid, the content of the above nitrile compound may be in the range of 50% by weight to 90% by weight. The lower limit (unit: % by weight) of the above range may be 55, 60, 65 or 70. The upper limit (unit: % by weight) of the above range may be 85, 80 or 75. Within the content range of the above nitrile compound, the ionic conductivity of the polymer solid electrolyte can be improved.

[0068] The above second liquid may further contain an additive to better disperse the above nitrile compound in the polymer solid electrolyte. The above additive may be, for example, an alkylene fluorocarbonate.

[0069] That is, the above second liquid may also contain an alkylene fluorocarbonate. At the initial stage of the charge / discharge process of a battery using a polymer electrolyte, the alkylene fluorocarbonate can form a protective layer called a Solid Electrolyte Interphase (SEI) between the cathode and the polymer electrolyte. The protective layer formed in this way can improve the battery driving performance and life.

[0070] The type of the above alkylene fluorocarbonate is also not restrictive. The above alkylene fluorocarbonate is a component that plays the role of appropriately dispersing components such as the above nitrile compound in the polymer matrix and can be selected from known components. Preferably, the above alkylene fluorocarbonate is ethylene fluorocarbonate.

[0071] The content of the above alkylene fluorocarbonate can also be appropriately controlled. For example, relative to 100 parts by weight of the above nitrile compound, the content of the above alkylene fluorocarbonate may be in the range of 1 part by weight to 10 parts by weight. The lower limit (unit: part by weight) of the above range may be 2, 3, 4 or 5. The upper limit (unit: part by weight) of the above range may be 9, 8, 7, 6 or 5. Within the above range, the function of the SEI formed by the above alkylene fluorocarbonate can be maximally exerted.

[0072] As described above, the polymer solid electrolyte composition of the present invention can be used to manufacture the polymer solid electrolyte applied in a lithium secondary battery. Specifically, the polymer solid electrolyte composition of the present invention can be used to manufacture the polymer solid electrolyte applied in a lithium metal battery. Therefore, the above polymer solid electrolyte composition, specifically the above second liquid, can also contain a lithium salt in the same way as the above first liquid.

[0073] Examples of the above lithium salt can be LiPF6, LiBF4, LiCF3SO3, Li(CF3SO2)2N, Li(CF3SO2)3C, LiC2F5SO3, Li(FSO2)2N, LiC4F9SO3, LiN(SO2CF2CF3)2, LiN(CN)2, etc. Preferably, the lithium salt is Li(CF3SO2)2N.

[0074] The present invention does not limit the content of the lithium salt. The above lithium salt can be appropriately added to such an extent that the electrolyte of the present invention exhibits sufficient activity. For example, in the above second liquid, the concentration of the above lithium salt can be in the range of 0.5 M to 2 M. The lower limit (unit: M) of the above range can be 0.6, 0.7, 0.8, 0.9 or 1.0. The upper limit (unit: M) of the above range can be 1.9, 1.8, 1.7, 1.6, 1.5, 1.4, 1.3, 1.2, 1.1 or 1.0.

[0075] The mixing ratio of the above first liquid and the above second liquid can also be appropriately controlled. For example, the weight ratio (A / B) of the above first liquid (A) to the above second liquid (B) can be in the range of 2 to 4. Within the above range, the bonding force between the polymer solid electrolyte and the electrode, the ionic conductivity of the polymer solid electrolyte, and the performance of the battery can be sufficiently ensured.

[0076] The present invention can be a solvent-free composition. Specifically, the above first liquid and second liquid can be solvent-free compositions. That is, the above first liquid and the above second liquid may not contain a solvent. In the present invention, deformation of the electrolyte caused by solvent volatilization (or evaporation by heating), such as pinholes, does not occur. At this time, the present invention can obtain an electrolyte film with a more uniform thickness and an improved bonding force with the electrode.

[0077] If the polymer solid electrolyte composition of the present invention prepared according to the above content is processed by heating at a predetermined temperature or the like, a polymer solid electrolyte can be obtained.

[0078] Polymer solid electrolyte

[0079] Another aspect of the present invention is a polymer solid electrolyte.

[0080] The polymer solid electrolyte of the present invention comprises at least a polymer matrix and a dispersed monomer dispersed in the polymer matrix.

[0081] In the polymer solid electrolyte of the present invention, the compositions of the polymer matrix and the dispersed monomer are adjusted.

[0082] The polymer matrix contains a polymerization unit derived from polyalkylene glycol (meth)acrylate, a polymerization unit derived from ethylene carbonate alkylene ester, and a polymerization unit derived from polyfunctional (meth)acrylate.

[0083] The dispersed monomer contains a nitrile compound represented by Chemical Formula 1:

[0084] [Chemical Formula 1]

[0085] CN-X-CN

[0086] In Chemical Formula 1, X is a substituted or unsubstituted linear or branched alkylene group having 1 to 20 carbon atoms.

[0087] If the components mentioned in the above polymer solid electrolyte composition are provided, it can also be directly applied to the polymer solid electrolyte.

[0088] In addition, the above polymer solid electrolyte may contain the above polymer solid electrolyte composition. In addition, the above polymer solid electrolyte may be derived from the above polymer solid electrolyte composition. In addition, the above polymer solid electrolyte may be formed from the above polymer solid electrolyte composition. In addition, the above polymer solid electrolyte may be a cured product or a dried product of the above polymer solid electrolyte composition.

[0089] The polymer solid electrolyte with the above specific components has a solid shape. In addition, the conductivity of the polymer electrolyte is also excellent.

[0090] As described above, the above polyfunctional (meth)acrylate is used as a crosslinking agent. Therefore, in the above polymer solid electrolyte, the above polyfunctional (meth)acrylate can form a crosslinked structure. This crosslinked structure can improve the conductivity of the polymer solid electrolyte.

[0091] Specifically, the above polymer matrix may have a structure in which the polymer is crosslinked by a crosslinking agent. More specifically, in the above polymer matrix, the polymer containing the polymerization unit derived from polyalkylene glycol (meth)acrylate and the polymerization unit derived from ethylene carbonate alkylene ester can be crosslinked by the polymerization unit derived from polyfunctional (meth)acrylate. This crosslinked structure can improve the adhesion force with the electrode in the battery.

[0092] The polymer solid electrolyte of the present invention can be applied to lithium secondary batteries. Therefore, components additionally contained in the above-mentioned first liquid and / or second liquid, such as lithium salts and / or fluoroalkyl carbonates, etc., can be included in the above-mentioned polymer solid electrolyte. Their types and contents also follow the above description.

[0093] Especially when fluoroalkyl carbonate is additionally contained in the above-mentioned second liquid, the polymer solid electrolyte of the present invention can significantly contribute to improving the battery life. As described above, at the initial stage of the charge / discharge process of a battery using a polymer electrolyte, fluoroalkyl carbonate can form a protective layer called Solid Electrolyte Interphase (SEI) between the cathode and the polymer electrolyte. The protective layer formed in this way can improve the battery driving performance and life.

[0094] In addition, the above-mentioned fluoroalkyl carbonate is dispersed in the above-mentioned polymer matrix in the above-mentioned polymer solid electrolyte in the same way as the above-mentioned nitrile compound.

[0095] Lithium secondary battery

[0096] Another aspect of the present invention relates to a lithium secondary battery. Specifically, the lithium secondary battery of the present invention is a all-solid-state battery. More specifically, the lithium secondary battery of the present invention is an all-solid-state battery using the polymer solid electrolyte of the present invention as the electrolyte.

[0097] Therefore, the lithium secondary battery of the present invention includes: a solid electrolyte layer containing a polymer solid electrolyte; an anode layer on one side of the above-mentioned solid electrolyte layer; and a cathode layer on the opposite side of the above-mentioned anode layer with respect to the above-mentioned solid electrolyte layer as a reference.

[0098] When describing the lithium secondary battery of the present invention, unless otherwise specifically restricted, all elements required for describing its structure can be appropriately selected from known elements.

[0099] The polymer solid electrolyte of the present invention is particularly suitable for lithium metal batteries. A lithium metal battery is a lithium secondary battery containing lithium metal as the cathode material.

[0100] In addition, the polymer solid electrolyte of the present invention is suitable for a lithium metal battery specifically specifying the composition of the anode material. At this time, the polymer solid electrolyte can be closely combined with the anode to significantly reduce the battery resistance.

[0101] For example, the above-mentioned anode layer can contain a compound represented by the following Chemical Formula 2, and the above-mentioned cathode layer can be a lithium metal battery containing lithium metal:

[0102] [Chemical Formula 2]

[0103] LiNia Co b Mn c O2 (0.6 ≤ a ≤ 0.9, a + b + c = 1).

[0104] Preferably, in Chemical Formula 2 above, a is close to 0.8, and b and c are each close to 0.1.

[0105] When the anode layer contains the above compound and the cathode layer contains lithium metal, if the polymer solid electrolyte is in close contact with the anode, the effect of improving the battery life can be maximized.

[0106] Hereinafter, the present invention will be described in detail by way of examples. However, the following examples do not limit the present invention.

[0107] [Material Information]

[0108] Poly(ethylene glycol)methacrylate (PEGMA): Mn 500, Sigma-Aldrich

[0109] Vinylethylene carbonate (VEC): Sigma-Aldrich

[0110] Poly(ethylene glycol)diacrylate (PEGDA): Mn 700, Sigma-Aldrich

[0111] Succinonitrile (SN): Sigma-Aldrich

[0112] LiTFSI: Sigma-Aldrich

[0113] Fluoroethylene carbonate (FEC): Sigma-Aldrich

[0114] [Example 1] Polymer Solid Electrolyte Composition

[0115] (1) First Liquid

[0116] Put 2 g of PEGMA, 0.2 g of PEGDA, 0.2 g of VEC, and 0.65 g of LiTFSI on a hot plate and mix them at 30 °C for 2 hours. Then, put 0.01 g of AIBN on the hot plate and mix for 1 hour to produce the first liquid. At this time, the concentration of LiTFSI is 1 M.

[0117] (2) Second Liquid

[0118] Put 2 g of SN, 0.1 g of FEC, and 0.58 g of LiTFSI on a hot plate and mix them at 50 °C for 3 hours to produce the second liquid. At this time, the concentration of LiTFSI is 1 M.

[0119] (3) Mixing

[0120] Mix the above-mentioned first liquid and second liquid at a weight ratio of 3:1 and mix them at 40 °C for 1 hour to produce the polymer solid electrolyte composition.

[0121] [Example 2] Polymer solid electrolyte composition

[0122] Mix the above-mentioned first liquid and second liquid at a weight ratio of 4:1, and repeat the same process as in Example 1 except for this.

[0123] [Example 3] Polymer solid electrolyte composition

[0124] Mix the above-mentioned first liquid and second liquid at a weight ratio of 2:1, and repeat the same process as in Example 1 except for this.

[0125] [Example 4] Polymer solid electrolyte composition

[0126] Change the content of PEGDA to 20 parts by weight relative to 100 parts by weight of PEGMA, and repeat the same process as in Example 1 except for this.

[0127] [Comparative Example 1] Polymer solid electrolyte composition

[0128] Do not use the second liquid, and repeat the same process as in Example 1 except for this.

[0129] [Comparative Example 2] Polymer solid electrolyte composition

[0130] Do not use PEGDA when manufacturing the first liquid, and repeat the same process as in Example 1 except for this.

[0131] [Comparative Example 3] Polymer solid electrolyte composition

[0132] Do not use VEC when manufacturing the first liquid, and repeat the same process as in Example 1 except for this.

[0133] [Experimental Example 1] SEM photograph taking

[0134] Coat the polymer solid electrolyte composition of Example 1 on the NCM811 electrode (loading amount: 6 mg / cm using aluminum foil as the substrate 2)。Then, in an oven at 100 °C, heat the above electrodes for 2 hours to fabricate a polymer solid electrolyte-electrode assembly.

[0135] Cut the cross-section of the above polymer solid electrolyte-electrode assembly using liquid nitrogen. Then, analyze its cross-section using SEM (HITACHI SU-8220).

[0136] Figure 2 This is the result (SEM photograph) of Experimental Example 1. It can be confirmed that good bonding between the polymer solid electrolyte and the electrode has been achieved.

[0137] [Experimental Example 2] Coin Cell Resistance Evaluation

[0138] 1) NCM811-Electrolyte Sealed Structure

[0139] Coat the polymer solid electrolyte compositions of the examples and comparative examples on an NCM811 electrode (loading: 6 mg / cm 2 ) using aluminum foil as the substrate. Then, in an oven at 100 °C, heat the above electrodes for 2 hours to fabricate a polymer solid electrolyte-electrode assembly. For this assembly, with the above polymer solid electrolyte as the reference, place a 200-μm-thick Li metal electrode as the cathode on the opposite side of the electrode to fabricate a 2032 coin cell composed of NCM811-electrolyte-Li metal, and then evaluate its internal resistance. The diameters of the Li metal electrode and the NCM811 electrode are each 16 mm. As the impedance measurement device, use MP1 from WonATech. The measurement conditions are at room temperature and in the frequency range of 1 Hz to 1 MHz.

[0140] 2) NCM811-Electrolyte Non-Sealed Structure

[0141] In addition, coat the polymer solid electrolyte composition of Example 1 on a glass plate and heat it in an oven at 100 °C for 2 hours to fabricate a polymer solid electrolyte membrane.

[0142] Place this solid electrolyte membrane between a 200-μm-thick Li metal electrode and an NCM811 electrode (loading: 6 mg / cm 2 ) using aluminum foil as the substrate and crimp them to fabricate a 2032 coin cell composed of NCM811-electrolyte-Li metal, and then evaluate its internal resistance. The diameters of the Li metal electrode and the NCM811 electrode are each 16 mm. As the impedance measurement device, use MP1 from WonATech. The measurement conditions are at room temperature and in the frequency range of 1 Hz to 1 MHz.

[0143] [Experimental Example 3] Ion Conductivity Evaluation

[0144] The polymer solid electrolytes of the examples and comparative examples were coated on a Li metal electrode with a thickness of 200 μm. Then, the above electrode was heated in an oven at 100 °C for 2 hours to fabricate a polymer solid electrolyte - electrode assembly. For this assembly, with the above polymer solid electrolyte as a reference, a 200 - μm - thick Li metal electrode serving as the cathode was placed on the opposite side of the electrode, thereby fabricating a 2032 button cell composed of Li metal - electrolyte - Li metal, and then its internal resistance was evaluated. The diameters of both electrodes were 16 mm each. As the impedance measurement device, MP1 from WonATech was used. The measurement conditions were normal temperature and a frequency range of 1 Hz to 1 MHz.

[0145] [Experimental Example 4] Battery Life Evaluation

[0146] For the button cells prepared in Experimental Example 2, battery life evaluation was carried out at normal temperature. Charging / discharging was performed at 0.3C, and at this time, the voltage range was 3.0 V to 4.3 V. The battery life was calculated by the discharge retention rate. Specifically, based on the initial battery discharge capacity, the number of charge - discharge cycles when the discharge capacity reached 80% was defined as the battery life.

[0147] [Results]

[0148] Table 1 shows the ionic conductivities of the polymer solid electrolytes of the examples and comparative examples and the results of the resistance evaluation of the lithium secondary batteries (button cells).

[0149] [Table 1]

[0150]

[0151] It can be confirmed from the examples and comparative examples that the conductivity of the polymer solid electrolyte defined in the present invention is higher, and the battery resistance of the lithium secondary battery fabricated therefrom is improved (decreased). From the evaluation results additionally carried out for Example 1 (indicated in parentheses in the results of Table 1), it can be confirmed that when the anode and the electrolyte of a specific composition have a closely - bonded structure, the battery life can be further improved. From Comparative Example 1, it can be seen that if a two - liquid composition of a specific composition is not used to fabricate the polymer solid electrolyte, the conductivity decreases and the battery resistance is poor. In Comparative Example 2, a solid polymer solid electrolyte was not fabricated, so further evaluation could not be carried out. From the results of Comparative Example 3, it can be seen that since a specific monomer was not introduced into the polymer structure, the battery life was shortened.

Claims

1. A polymer solid electrolyte composition comprising a first liquid and a second liquid, wherein the first liquid comprises a polyalkylene glycol (meth)acrylate, an ethylene alkylene carbonate, and a polyfunctional (meth)acrylate, the second liquid comprises a nitrile compound represented by Chemical Formula 1, [Chemical Formula 1] CN-X-CN In Chemical Formula 1, X is a substituted or unsubstituted linear or branched alkylene having 1 to 20 carbon atoms.

2. The polymer solid electrolyte composition according to claim 1, wherein the polyalkylene glycol (meth)acrylate is polyethylene glycol methacrylate.

3. The polymer solid electrolyte composition according to claim 1, wherein the number average molecular weight of the polyalkylene glycol (meth)acrylate is in the range of 100 to 1000.

4. The polymer solid electrolyte composition according to claim 1, wherein, based on the total weight of the first liquid, the content of the polyalkylene glycol (meth)acrylate is in the range of 50 wt% to 90 wt%.

5. The polymer solid electrolyte composition according to claim 1, wherein the ethylene alkylene carbonate is ethylene ethylene carbonate.

6. The polymer solid electrolyte composition according to claim 1, wherein, relative to 100 parts by weight of the polyalkylene glycol (meth)acrylate, the content of the ethylene alkylene carbonate is in the range of 10 parts by weight to 20 parts by weight.

7. The polymer solid electrolyte composition according to claim 1, wherein the polyfunctional (meth)acrylate is a polyalkylene glycol di(meth)acrylate.

8. The polymer solid electrolyte composition according to claim 7, wherein the polyfunctional (meth)acrylate is polyethylene glycol diacrylate.

9. The polymer solid electrolyte composition according to claim 7, wherein the number average molecular weight of the polyalkylene glycol di(meth)acrylate is in the range of 500 to 1500.

10. The polymer solid electrolyte composition according to claim 1, wherein X in Chemical Formula 1 is ethylene.

11. The polymer solid electrolyte composition according to claim 1, wherein, based on the total weight of the second liquid, the content of the nitrile compound is in the range of 50 wt% to 90 wt%.

12. The polymer solid electrolyte composition according to claim 1, further comprising 1 to 10 parts by weight of a fluoroalkylene carbonate relative to 100 parts by weight of the nitrile compound.

13. The polymer solid electrolyte composition according to claim 12, wherein the fluoroalkylene carbonate is fluoroethylene carbonate.

14. The polymer solid electrolyte composition according to claim 1, wherein the weight ratio of the first liquid A to the second liquid B, i.e., A / B, is in the range of 2 to 4.

15. A polymer solid electrolyte comprising a polymer matrix and a dispersed monomer, wherein the polymer matrix comprises a polymerization unit derived from a polyalkylene glycol (meth)acrylate, a polymerization unit derived from an ethylene alkylene carbonate, and a polymerization unit derived from a polyfunctional (meth)acrylate. The dispersion monomer is dispersed in the polymer matrix and contains a nitrile compound represented by Chemical Formula 1. [Chemical Formula 1] CN-X-CN In Chemical Formula 1, X is a substituted or unsubstituted linear or branched alkylene group having 1 to 20 carbon atoms.

16. The polymer solid electrolyte according to claim 15, wherein the polymer containing the polymerization unit derived from polyalkylene glycol (meth)acrylate and the polymerization unit derived from ethylene alkylene carbonate is crosslinked by the polymerization unit derived from a polyfunctional (meth)acrylate.

17. The polymer solid electrolyte according to claim 16, further comprising a fluorinated alkylene carbonate dispersed in the polymer matrix.

18. A lithium secondary battery, comprising: a solid electrolyte layer containing the polymer solid electrolyte according to claim 15; an anode layer on one side of the solid electrolyte layer; and a cathode layer on the opposite side of the anode layer with respect to the solid electrolyte layer.

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