Lithium secondary battery solid electrolyte comprising core-shell-structured cationic polymer, and lithium secondary battery comprising same

Abstract

The present invention relates to a precursor composition for preparing a lithium secondary battery solid electrolyte comprising a lithium-rich cathode, and to: a precursor composition for preparing a solid electrolyte; a solid electrolyte obtained by crosslinking same; and a secondary battery comprising a lithium-rich cathode that comprises same, the composition comprising a core layer that includes a liquid electrolyte and a shell layer that comprises a cationic polymer and encompasses the core layer. The lithium secondary battery solid electrolyte comprising a lithium-rich cathode, of the present invention, introduces a shell-structured cationic polymer having a cationic charge and a crosslinking site in the solid electrolyte, so as to form an ion-ion interaction between the solid electrolyte and an anionic charge on the surface of a layered Li-rich manganese oxide (LLO) active material, thereby reducing oxygen interlayer repulsive energy, known as a driving force of irreversible oxygen release, so as to promote structural stabilization of a lithium-rich cathode material, and thus solves a fundamental problem that occurs when using a lithium-rich layered oxide. As a result, the amount of generated oxygen is reduced such that an interfacial instability problem caused by side reactions among oxygen, the electrolyte and lithium can be solved. In addition, the lithium secondary battery solid electrolyte comprising the lithium-rich cathode, of the present invention, can be self-crosslinked even without using a crosslinking agent.

Description

Solid electrolyte for lithium secondary batteries comprising a cationic polymer having a core-shell structure and a lithium secondary battery comprising the same

[0001] The present invention relates to a solid electrolyte for a lithium secondary battery including an excess lithium anode and a lithium secondary battery including the same, and more particularly, to a solid electrolyte using a cationic polymer for stabilizing the structure of an excess lithium anode in a lithium secondary battery including the excess lithium anode, and a lithium secondary battery including the same.

[0002] Lithium secondary batteries are used in diverse fields such as electric vehicles (EVs), vacuum cleaners, electric bicycles, various robots, and large-scale energy storage systems (ESS). The cathode and anode materials of lithium secondary batteries determine the battery capacity, and thus, lithium secondary batteries have limited capacity due to the material limitations of these electrodes. In particular, secondary batteries used in electric vehicles must be able to operate for a long time after a single charge, making discharge capacity crucial. To overcome the capacity limitations of lithium secondary batteries, the development of a new concept that transcends the principles of existing secondary batteries is required.

[0003] In general, the discharge specific capacity of secondary battery cathode materials is less than 200 mAh / g, which is not sufficient to be used as a power source that guarantees the driving range and stable operation of electric vehicles. To overcome the limitation of reversible capacity, secondary batteries that introduce high-energy density lithium anodes are being studied. However, lithium anodes in secondary batteries have electrochemical problems such as irreversible oxygen release reaction, in which oxygen is excessively oxidized and turns into gas during initial charge and discharge, which can cause the structure of the cathode active material to collapse and cause a voltage drop. In addition, electrolyte decomposition due to high-voltage operation increases resistance and generates gas.

[0004] To solve this problem, research on electrolytes for lithium secondary batteries has mainly focused on achieving interface stabilization and structural stabilization through the formation of a stable CEI (Cathode Electrolyte Interphase) using additives or high-concentration liquid electrolytes.

[0005] However, the problem of destabilization of the structure itself due to irreversible oxygen release still exists, and research to fundamentally solve the problem of irreversible oxygen release has not been conducted.

[0006] The purpose of the present invention is to provide a precursor composition for manufacturing a solid electrolyte using a cationic polymer to realize structural stabilization of an excess lithium positive electrode.

[0007] In addition, another object of the present invention is to provide a solid electrolyte for a lithium secondary battery including an excess lithium positive electrode manufactured using the precursor composition for manufacturing the solid electrolyte.

[0008] In addition, another object of the present invention is to provide a lithium secondary battery containing an excess lithium positive electrode including the solid electrolyte.

[0009] In addition, another object of the present invention is to provide a device including the lithium secondary battery.

[0010] In addition, another object of the present invention is to provide a method for manufacturing a precursor composition for manufacturing a solid electrolyte using a cationic polymer in order to realize structural stabilization of an excess lithium positive electrode.

[0011] In addition, another object of the present invention is to provide a method for manufacturing a lithium secondary battery, including a method for manufacturing the solid electrolyte.

[0012] The precursor composition for manufacturing a solid electrolyte of a lithium secondary battery including an excess lithium positive electrode of the present invention to achieve the above-mentioned purpose may include a core layer including a liquid electrolyte; and a shell layer surrounding the core layer as a cationic polymer.

[0013] The above cationic polymer may be a compound represented by the following [structural formula 1];

[0014] [Structural formula 1]

[0015]

[0016] In the above structural formula 1, R1 and R3 are each independently primary to quaternary ammonium (-NH3 + , -NH2R` + , -NHR`2 + , -NR`3 + ), pyridinium (-Py + ), imidazolium (-Im + ), triazolium(-Trz + ), thiazolium (-Thz + ), phosphonium (e.g. -PR`3 + ), sulfonium (e.g. -SR`2 + ) or hydrazonium(-N2H5 + ) is a functional group of the series, wherein R` is a C1 to C4 alkyl group or an allyl group,

[0017] The above R2 is tertiary ammonium or quaternary ammonium (-NR6R7- + ) and,

[0018] The above R4 and R5 are each independently or And,

[0019] The above R6 is , or and,

[0020] The above R7 and R8 are each independently hydrogen, a C1 to C4 alkyl group or an allyl group,

[0021] The above n1 to n7 are repeating unit numbers and are each independently an integer from 1 to 10.

[0022] Preferably, in the above [structural formula 1], R1 and R3 are each independently primary to quaternary ammonium (-NH3 + , -NH2R` + , -NHR`2 + , -NR`3 + ) is a functional group of the series, wherein R` is a C1 to C4 alkyl group,

[0023] The above R2 is quaternary ammonium (-NR6R7- + ) and,

[0024] The above R4 and R5 are each independently And,

[0025] The above R6 is , or and,

[0026] The above R7 and R8 are each independently a C1 to C4 alkyl group,

[0027] The above n1 to n7 are repeating unit numbers and are each independently integers from 1 to 4.

[0028] More preferably, the compound represented by the above [structural formula 1] may be a compound represented by any one selected from the following [chemical formula 1] to [chemical formula 3];

[0029] [Chemical Formula 1]

[0030]

[0031] [Chemical Formula 2]

[0032]

[0033] [Chemical Formula 3]

[0034]

[0035] The cationic polymer can form a pair with a counter anion of the cation; the counter anion is N(SO2CF3)2 -(TFSI - ), N(COCF3)(SO2CF3) - , N(SO2F)2 - , N(CN)2 - , NO3 - , tetraphenylborate, BF4 - , B(CN)4 - , CH3BF3 - , CH2CHBF3 - , CF3BF3 - , C2F5BF3 - , n-C3F7BF3 - , n-C4F9BF3 - , PF7 - , CF3CO2 - , CF3SO3 - , C(CN)3 - , SCN - , SeCN - , CuCl2 - and AlCl4 - It can be any one of the following:

[0036] The solvent included in the above liquid electrolyte may be at least one selected from ethylene carbonate (EC), propene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), ethyl acetate (EC), methyl propionate (MP), ethyl propionate (EP), and propyl propionate (PP).

[0037] The above cationic polymer and liquid electrolyte can be mixed in a weight ratio of 1:2-15.

[0038] The above-mentioned excess lithium anode may include an excess lithium-based layered oxide (LLO, Layered Li-rich Manganese Oxides) represented by the following [chemical formula 4];

[0039] [Chemical Formula 4]

[0040] Li 1+x Mn y M z O 2+w

[0041] In the above chemical formula 1, x and w are each independently integers from 1 to 3,

[0042] y and z are each independently 0.10 to 0.9,

[0043] M additionally includes at least one selected from Ni, Al, Mg, Ti, Fe, and Nb.

[0044] The precursor composition for manufacturing the above solid electrolyte may not contain a crosslinking agent.

[0045] In addition, the solid electrolyte for a lithium secondary battery including the excess lithium positive electrode of the present invention for achieving the other purpose described above may be a solid electrolyte prepared by curing the precursor composition for preparing the solid electrolyte by ultraviolet treatment.

[0046] In addition, an all-solid-state lithium secondary battery including an excess lithium positive electrode of the present invention for achieving another purpose described above may include an excess lithium positive electrode; an anode; and the solid electrolyte positioned between the excess lithium positive electrode and the anode.

[0047] The above excess lithium anode may include an excess lithium layered oxide (LLO, Layered Li-rich Manganese Oxides) represented by the above [chemical formula 4].

[0048] The above negative electrode may include at least one selected from the group consisting of lithium metal, silicon-carbon composite, tin-based alloy, silicon, lithium titanate (LTO), soft carbon, hard carbon, and graphite.

[0049] In addition, the device of the present invention for achieving the above-mentioned another purpose may be any one selected from among portable electronic devices, mobile units, power devices, and energy storage devices including the above-mentioned all-solid-state lithium secondary battery.

[0050] In addition, a method for manufacturing a solid electrolyte for a lithium secondary battery including an excess lithium positive electrode of the present invention for achieving another purpose described above may include a step of preparing a precursor composition for manufacturing the solid electrolyte; and a step of ultraviolet curing the precursor composition for manufacturing the solid electrolyte to manufacture a polymer electrolyte.

[0051] In addition, the method for manufacturing a lithium secondary battery of the present invention for achieving another purpose described above may include a method for manufacturing the solid electrolyte.

[0052] The solid electrolyte for a lithium secondary battery including the excess lithium positive electrode of the present invention is introduced as a shell structure that surrounds a liquid electrolyte with a cationic polymer having a cationic charge and a cross-linking site in the solid electrolyte, thereby forming an ion-ion interaction between the negative charge on the surface of the solid electrolyte and the excess lithium layered oxide (LLO) active material, thereby reducing the repulsive energy between oxygen layers, which is known as the driving force for irreversible oxygen release, thereby stabilizing the structure of the excess lithium positive electrode material, thereby solving the fundamental problem that occurs when using the excess lithium layered oxide, and as a result, the amount of oxygen generated is reduced, thereby solving the problem of interface instability caused by side reactions among oxygen, electrolyte, and lithium.

[0053] In addition, the solid electrolyte for a lithium secondary battery including the excess lithium positive electrode of the present invention can self-crosslink without using a crosslinking agent, has excellent thermal stability, and can be applied to other high-voltage active materials (i.e., NCM811).

[0054] Figure 1 is a schematic diagram showing the ion-ion interaction between an active material, which is a layered oxide (LLO) based on excess lithium, and a cationic polymer through the control of intermolecular interactions in a lithium secondary battery including an excess lithium positive electrode of the present invention.

[0055] Figure 2 is a cross-sectional view showing the structure of the precursor composition of the present invention.

[0056] FIG. 3a is a graph measuring the amount of oxygen generated by an electrode manufactured according to Example 1 and Comparative Example 3 of the present invention, and FIG. 3b is a graph measuring the pressure of an electrode manufactured according to Example 1 and Comparative Example 3 of the present invention.

[0057] Figures 4a and 4b are XANES spectra obtained from XANES measurements of electrodes manufactured according to Example 1 and Comparative Example 3, respectively.

[0058] Figure 5 is an EXAFS spectrum obtained from EXAFS measurement of electrodes manufactured according to Example 1 and Comparative Example 3.

[0059] Figure 6 is a photograph taken by TEM of the surface of an electrode manufactured according to Example 1 and Comparative Example 3 of the present invention.

[0060] Figure 7 is a graph showing the results of measuring electrodes manufactured according to Example 1 and Comparative Example 3 of the present invention using Differential Scanning Calorimeter (DSC).

[0061] Figure 8 shows the electrochemical performance of a pouch-type battery including an electrode manufactured according to Example 1 of the present invention.

[0062] Below, various aspects and various implementation examples of the present invention are described in more detail.

[0063] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings so that those skilled in the art can easily implement the present invention.

[0064] However, the following description is not intended to limit the present invention to a specific embodiment, and when explaining the present invention, if it is determined that a detailed description of a related known technology may obscure the gist of the present invention, the detailed description is omitted.

[0065] The terminology used herein is for the purpose of describing specific embodiments only and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, it should be understood that the terms "comprises" or "has" indicate the presence of a feature, number, step, operation, component, or combination thereof described in the specification, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, or combinations thereof.

[0066]

[0067] Figure 1 is a schematic diagram showing the ion-ion interaction between an active material, which is a layered oxide (LLO) based on excess lithium, and a cationic polymer through the control of intermolecular interactions in a lithium secondary battery including an excess lithium positive electrode of the present invention.

[0068] Hereinafter, with reference to FIG. 1, a precursor composition for manufacturing a solid electrolyte of a lithium secondary battery including an excess lithium positive electrode of the present invention will be described.

[0069] The precursor composition of the present invention comprises a core layer including a liquid electrolyte; and a shell layer surrounding the core as a cationic polymer (Fig. 2).

[0070] According to one embodiment of the present invention, the cationic polymer may be a compound represented by the following [structural formula 1], and since a plurality of cationic functional groups are substituted, an ion-ion interaction is formed between the anionic charge on the surface of the solid electrolyte and the layered Li-rich Manganese Oxides (LLO) active material, thereby reducing the repulsive energy between oxygen layers, which is known as the driving force for irreversible oxygen release, and thus stabilizing the structure of the excess lithium cathode material.

[0071] [Structural formula 1]

[0072]

[0073] In the above structural formula 1, R1 and R3 are each independently primary to quaternary ammonium (-NH3 + , -NH2R` + , -NHR`2 + , -NR`3 + ), pyridinium (-Py + ), imidazolium (-Im + ), triazolium(-Trz + ), thiazolium (-Thz + ), phosphonium (e.g. -PR`3 + ), sulfonium (e.g. -SR`2 + ) or hydrazonium(-N2H5 + ) is a functional group of the series, wherein R` is a C1 to C4 alkyl group or an allyl group,

[0074] The above R2 is tertiary ammonium or quaternary ammonium (-NR6R7- + ) and,

[0075] The above R4 and R5 are each independently or And,

[0076] The above R6 is , or and,

[0077] The above R7 and R8 are each independently hydrogen, a C1 to C4 alkyl group or an allyl group,

[0078] The above n1 to n7 are repeating unit numbers and are each independently an integer from 1 to 10.

[0079] Preferably, in the above structural formula 1, R1 and R3 are each independently primary to quaternary ammonium (-NH3 + , -NH2R` + , -NHR`2 + , -NR`3 +) is a functional group of the series, wherein R` is a C1 to C4 alkyl group,

[0080] The above R2 is quaternary ammonium (-NR6R7- + ) and,

[0081] The above R4 and R5 are each independently And,

[0082] The above R6 is , or and,

[0083] The above R7 and R8 are each independently a C1 to C4 alkyl group,

[0084] The above n1 to n7 are repeating unit numbers and are each independently integers from 1 to 4.

[0085] More preferably, the compound represented by the structural formula 1 may be a compound represented by any one selected from the following [chemical formula 1] to [chemical formula 3].

[0086] [Chemical Formula 1]

[0087]

[0088] [Chemical Formula 2]

[0089]

[0090] [Chemical Formula 3]

[0091]

[0092] Since the compounds of the above [chemical formula 1] to [chemical formula 3] have a large number of carbon double bonds, self-crosslinking is possible without using a crosslinking agent.

[0093] According to another embodiment of the present invention, the cationic polymer may form a pair with the counter anion of the cation.

[0094] The above counter anion is not particularly limited as long as it can form a pair with the cationic polymer, but is preferably N(SO2CF3)2. -(TFSI - ), N(COCF3)(SO2CF3) - , N(SO2F)2 - , N(CN)2 - , NO3 - , tetraphenylborate, BF4 - , B(CN)4 - , CH3BF3 - , CH2CHBF3 - , CF3BF3 - , C2F5BF3 - , n-C3F7BF3 - , n-C4F9BF3 - , PF7 - , CF3CO2 - , CF3SO3 - , C(CN)3 - , SCN - , SeCN - , CuCl2 - and AlCl4 - It may be any one selected from; more preferably N(SO2CF3)2 - (TFSI - ) may be.

[0095] According to another embodiment of the present invention, the liquid electrolyte comprises a solvent and a lithium salt.

[0096] The above solvent can be applied to compounds such as cyclic carbonate compounds, linear carbonate compounds, and linear ester compounds.

[0097] The cyclic carbonate solvent may be ethylene carbonate (EC), propylene carbonate (PC), etc.; the linear carbonate solvent may be dimethyl carbonate (MDC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), etc.; and the linear ester solvent may be ethyl acetate (EC), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), etc.

[0098] Preferably, a mixture of ethylene carbonate (EC) / diethyl carbonate (DEC) or a mixture of ethylene carbonate (EC) / ethyl methyl carbonate (EMC) can be used. When a solvent is applied in such a combination, the ionic conductivity of the electrolyte can be improved.

[0099] In addition, the lithium salts are LiPF6, LiCl, LiBr, LiI, LiClO4, LiBF4, LiB10Cl 10 , LiB(Ph)4, LiC4BO8, LiPF6, LiCF3SO3, LiCF3CO2, LiAsF6, LiSbF6, LiAlCl4, LiSO3CH3, LiSCN, LiC(CF3SO2)3, LiN(CF3SO2)2, LiN(C2F5SO2)2, Li[N(SO2CF3)2](LiTFSI), Li(SO3CF3)(LiTf), Li[N(SO2F)]2(LiFSI), etc. can be applied.

[0100] According to another embodiment of the present invention, the cationic polymer and the liquid electrolyte may be mixed in a weight ratio of 1:2-15, preferably 1:4-10, and more preferably 1:5-8. If the content of the liquid electrolyte is less than 2 weight ratio based on the cationic polymer, the total capacity and energy density may be reduced, and if it exceeds the upper limit, it may be difficult to perform self-crosslinking.

[0101] According to another embodiment of the present invention, the excess lithium positive electrode may include an excess lithium layered oxide (LLO, Layered Li-rich Manganese Oxides) represented by the following [chemical formula 4].

[0102] [Chemical Formula 4]

[0103] Li 1+x Mn y M z O 2+w

[0104] In the above chemical formula 1, x and w are each independently integers from 1 to 3,

[0105] y and z are each independently 0.10 to 0.9,

[0106] M additionally includes at least one selected from Ni, Al, Mg, Ti, Fe, and Nb.

[0107] However, the scope of the present invention is not limited thereto, and any possible form of excess lithium anode can be applied.

[0108]

[0109] In addition, the present invention provides a solid electrolyte for a lithium secondary battery including an excess lithium positive electrode cured by ultraviolet treatment of the precursor composition for preparing the solid electrolyte.

[0110] The precursor composition for manufacturing the above solid electrolyte can simultaneously function as a polymer additive and a cross-linking polymer to form a matrix of a solid electrolyte, since the cationic polymer simultaneously undergoes polymerization and self-cross-linking by ultraviolet treatment.

[0111]

[0112] In addition, the present invention provides an all-solid-state lithium secondary battery comprising an excess lithium positive electrode; an anode; and the solid electrolyte positioned between the excess lithium positive electrode and the anode.

[0113] The above solid electrolyte can stabilize the structure of the excess lithium anode by reducing the repulsive force between oxygen layers, which is the driving force for irreversible oxygen release, by forming an ion-ion interaction between the positive charge of the cationic polymer and the negative charge of the excess lithium anode at the interface with the excess lithium anode.

[0114] In this way, the amount of oxygen generated is reduced due to the structural stabilization of the excess lithium anode, which in turn prevents interface instability caused by side reactions between oxygen, electrolyte, and lithium.

[0115] The above excess lithium anode may include an excess lithium layered oxide (LLO, Layered Li-rich Manganese Oxides) represented by the above [chemical formula 4].

[0116] Examples of cathode materials applicable to the present invention include, but are not limited to, lithium metal, silicon-carbon composites, tin-based alloys, silicon, lithium titanate (LTO), soft carbon, hard carbon, graphite, etc.

[0117] Since the current collectors applied to all-solid-state lithium secondary batteries can be applied with the technology of conventional all-solid-state lithium secondary batteries, a detailed description will be omitted.

[0118]

[0119] The present invention also provides a device selected from among portable electronic devices, mobile units, power devices, and energy storage devices including an all-solid-state lithium secondary battery.

[0120]

[0121] In addition, the present invention provides a method for manufacturing a polymer electrolyte for a lithium secondary battery including an excess lithium positive electrode, the method comprising the steps of: preparing a precursor composition for manufacturing the solid electrolyte; and curing the precursor composition for manufacturing the solid electrolyte with ultraviolet rays to manufacture a polymer electrolyte.

[0122]

[0123] In addition, the present invention provides a method for manufacturing an all-solid-state lithium secondary battery including a method for manufacturing the polymer electrolyte.

[0124] Hereinafter, preferred examples are presented to help understand the present invention, but the following examples are only illustrative of the present invention, and it is obvious to those skilled in the art that various changes and modifications are possible within the scope and technical idea of ​​the present invention, and it is also natural that such changes and modifications fall within the scope of the appended patent claims.

[0125] Example 1. Solid electrolyte with core-shell structure

[0126] Preparation of cationic polymers

[0127] After synthesizing BEAG, an epoxy monomer, according to the following [Reaction Scheme 1], a cationic polymer represented by [Chemical Formula 1] was obtained using this according to the following [Reaction Scheme 2].

[0128] First, according to [Scheme 1], the synthesis of BEAG (Boc-protected ethanolamine glycidyl ether), an epoxy monomer containing a tert-butyloxycarbonyl group (Boc group), which is a protecting group for an amine group, was carried out. In the case of the epoxy monomer, in addition to the formation of beta-hydroxylamine, the synthesis is carried out in a form in which a Boc group, which is a protecting group for the amine group, is introduced to prevent polymerization side reactions due to additional epoxy-amine reactions. Specifically, ethanolamine and di-tert-butyl-dicarbonate are reacted in a dichloromethane solvent under triethylamine at room temperature for 6 hours to introduce a tert-butyloxycarbonyl group. The above reaction includes a step of solvent extraction using distilled water and dichloromethane and purification through column chromatography using ethyl acetate as a mobile phase. Thereafter, the product was reacted with epichlorohydrin in the presence of a TBAHSO4 (Tetrabutylammoniumhydrogensulfate) catalyst and potassium hydroxide as a base to obtain a BEAG epoxy monomer. The process was carried out by gradually increasing the reaction temperature from 0°C to room temperature for a total of 8 hours. The process includes a step of solvent extraction using distilled water and ethyl acetate and separation through column chromatography using a mixed solvent of hexane and ethyl acetate in a volume ratio of 2:1 as a mobile phase, and finally purification through fractional distillation.

[0129] Next, according to [Reaction Scheme 2], the synthesis of an intermediate in the form of beta-hydroxylamine proceeds through a solvent-free reaction between BEAG and allylamine at high temperature. The reaction is carried out at 80°C for 3 hours, and then an esterification reaction with methacryloyl chloride is carried out at room temperature for 16 hours under triethylamine base and 4-dimethylaminopyridine catalyst conditions to introduce a methacryloyl group as a crosslinking functional group. The reaction includes a solvent extraction process using distilled water and dichloromethane, and a purification step through column chromatography using a mixed solvent of hexane and ethyl acetate in a volume ratio of 3:2 as a mobile phase. Subsequently, the Boc protecting group is removed under acidic conditions to expose the primary amine group. This process was carried out for 16 hours after injecting hydrochloric acid, and then neutralized by injecting an aqueous potassium carbonate solution, followed by a quaternization reaction with methyl iodide at room temperature to obtain a cationic functional group. This reaction included a purification process through column chromatography in which the polarity was gradually increased in the order of acetone, acetone, and methanol in a volume ratio of 20:1, and methanol. Afterwards, lithium trifluorosulfonyl imide (LiTFSI) was dissolved together in a mixed solvent of methanol and dichloromethane in a volume ratio of 1:10, and the counteranion was exchanged through a reaction at room temperature for 16 hours to obtain a compound of [chemical formula 1]. Excess LiTFSI was removed through solvent extraction using distilled water and dichloromethane, ultimately obtaining the compound of [chemical formula 1].

[0130] [Reaction Formula 1]

[0131]

[0132] [Reaction Formula 2]

[0133]

[0134] Preparation of precursor solution for solid electrolyte production

[0135] A precursor solution was prepared by mixing the compound of [chemical formula 1], which is the cationic polymer manufactured above, and a liquid electrolyte (3 M LiPF6in EC / DMC / EMC (1 / 1 / 1, v / v / v)) at a weight ratio of 1:5.6.

[0136] Polymer electrolyte-based electrode manufacturing

[0137] Li2Ni, a lithium-rich layered oxide (LLO) 0.13 Co 0.13 Mn 0.54 The cathode was manufactured at a ratio of O2 / PvdF / Super P = 92 / 4 / 4 (w / w / w).

[0138] Specifically, NMP was added so that the solid content ratio [(LLO + PVDF + Super P) / (LLO + PVDF + Super P + NMP)] was 70% to prepare an electrode slurry. Thereafter, the slurry was cast on an Al current collector, and the NMP was dried at 80°C for 2 hours to prepare a cathode.

[0139] The surface of the anode thus manufactured was sufficiently impregnated with the precursor solution prepared above for 24 hours. This allowed the electrolyte to sufficiently permeate the pores within the anode. Subsequently, UV crosslinking was performed for 1 minute to achieve crosslinking.

[0140] As described above, a solid electrolyte formed into a core-shell structure was manufactured by polymerizing the crosslinking monomer through UV crosslinking for 1 minute. At this time, the solid electrolyte is obtained in the form of a cationic polymer surrounding a liquid electrolyte, and thus is formed into a structure of a core layer including a liquid electrolyte and a shell layer including a cationic polymer.

[0141]

[0142] Comparative Example 1.

[0143] An electrode was manufactured in the same manner as in Example 1, but using the compound of [Chemical Formula 5] instead of the compound of [Chemical Formula 1] as the cationic polymer.

[0144] [Chemical Formula 5]

[0145]

[0146]

[0147] Comparative Example 2.

[0148] An electrode was manufactured in the same manner as in Example 1, but using the compound of [Chemical Formula 6] below instead of the compound of [Chemical Formula 1] as the cationic polymer.

[0149] [Chemical Formula 6]

[0150]

[0151]

[0152] Comparative Example 3.

[0153] An electrode was manufactured in the same manner as in Example 1, but using a liquid electrolyte (3 M LiPF6in EC / DMC / EMC (1 / 1 / 1, v / v / v)) instead of the precursor solution for manufacturing a solid electrolyte.

[0154]

[0155] [Experimental Example]

[0156] Experimental Example 1: Evaluation of structural stability according to the type of cationic polymer.

[0157] The interaction between the cationic polymer / lithium excess electrode (LLO) surface charge was analyzed for the electrodes manufactured according to Example 1, Comparative Example 1, and Comparative Example 2.

[0158]

[0159] As shown in Table 1 above, it was confirmed that the electrode manufactured according to Example 1 of the present invention uses a compound of [chemical formula 1] as a cationic polymer to form a strong ion-ion interaction between the negative charges on the surface of the solid electrolyte and the excess lithium layered oxide (LLO) active material, thereby reducing the repulsive energy between the oxygen layers and promoting the structural stabilization of the excess lithium cathode material.

[0160] On the other hand, it was confirmed that the electrodes of Comparative Examples 1 and 2 had weak or no ion-ion interaction between the solid electrolyte and the negative charge on the surface of the excess lithium layered oxide (LLO) active material, so that the structure of the excess lithium cathode material was unstable and cracks occurred.

[0161]

[0162] Experimental Example 2: Evaluation of the effect of suppressing oxygen production

[0163] In the drawing, Pristine or Pristine LLO refers to the active material in the LLO electrode before battery charge / discharge is performed.

[0164] FIG. 3a is a graph measuring the amount of oxygen generated by an electrode manufactured according to Example 1 and Comparative Example 3 of the present invention, and FIG. 3b is a graph measuring the pressure of an electrode manufactured according to Example 1 and Comparative Example 3 of the present invention.

[0165] After manufacturing pouch-type batteries using the electrodes manufactured according to the above Example 1 and Comparative Example 3, charge and discharge were performed at 4.8 V, 0.05 C at 45°C for each pouch-type battery from which the internal gas was removed. At this time, the amount of oxygen generated during the initial charge and discharge was measured to calculate the cumulative amount of oxygen generated during the initial charge and discharge, and the pressure change was observed using a cell pressure meter. density: 2.63 g cm -3 ; C-rate: 0.05 C / 0.05 C; Areal capacity: 10 mAh cm -2

[0166] As shown in FIGS. 3a and 3b, it was confirmed that as charging progressed, the pressure inside the pouch battery increased as oxygen gas was generated, and it was confirmed that a lower amount of oxygen was generated in Example 1 compared to Comparative Example 3.

[0167] The reason why the amount of oxygen generated in Example 1 is small is because the cationic functional group of the cationic polymer acts to suppress oxygen generation, and it was confirmed that even in the anionic redox range (4.4-4.8 V) where the amount of oxygen generated is the greatest, the amount of oxygen generated was reduced compared to Comparative Example 3, resulting in a low pressure change.

[0168]

[0169] Experimental Example 3: Structural Stability Evaluation

[0170] Figures 4a and 4b are XANES spectra obtained from XANES measurements of electrodes manufactured according to Example 1 and Comparative Example 3, respectively.

[0171] In addition, FIG. 5 is an EXAFS spectrum obtained from EXAFS measurement of an electrode manufactured according to Example 1 and Comparative Example 3 of the present invention.

[0172] X-ray Absorption Spectroscopy (XAS) and X-ray Anion Spectroscopy (XANES) are both parts of X-ray Absorption Spectroscopy (XAS), and represent different sections of data obtained from the same experiment. In the XAS spectrum, XANEs are near the edge (~-20 eV to +50 eV), and EXAFs are after the edge (~+50 eV to +1000 eV or more). The XANEs are measured to analyze the oxidation state of transition metals, and the EXAFs are measured to identify the distance between surrounding atoms, bond lengths, etc.

[0173] Measurement location: Pohang Light Source, X-ray energy: ~0.15 eV, Beam size: 1 mm in diameter

[0174] Measurement range: Ni (8330~8360 eV), Co (7710~7730 eV), Mn (6530~6560 eV)

[0175] Measurement mode: total electron yield (TEY)

[0176]

[0177] As shown in Fig. 4a and Fig. 4b, the change in oxygen bonding strength during the cycling process was confirmed through Soft X-ray (XANE) measurement, and the electrode of Example 1 showed a pre-edge peak at 532 eV, which is the transition from O 1s to TM 3d-O 2p (t 2g ) means 1 st It was confirmed that the TM-O bonding strength was maintained very strongly from the cycle, so oxygen generation was suppressed and the structure was stable.

[0178] On the other hand, the electrode of comparative example 3 is 1 st After cycling, the TM-O bonding strength was rapidly reduced, confirming that oxygen was released and structural instability increased.

[0179]

[0180] In addition, as shown in Fig. 5, the change in the bonding energy (bonding strength) between transition metal / Li after cycling was confirmed through Hard X-ray (EXAFS) measurement. As the cycle progressed, the electrode of Example 1 was confirmed to have a Mn-TM / Li bonding strength almost similar to that of Pristine, which means that oxygen generation was suppressed and the structure was stable.

[0181] On the other hand, the electrode of Comparative Example 3 was confirmed to have a decrease in the (R, Mn-O) / (R, Mn-TM) ratio, which means that oxygen was released and structural instability increased.

[0182] Accordingly, it was confirmed that the electrode of Example 1 showed superior active material structural stability compared to Comparative Example 3.

[0183]

[0184] Experimental Example 4: Structural Stability Evaluation

[0185] Figure 6 is a photograph taken by TEM of the surface of an electrode manufactured according to Example 1 and Comparative Example 3 of the present invention.

[0186] As shown in Fig. 6, it was confirmed that a deep Spinel phase was formed in the electrode of Comparative Example 3, which means that a change occurred in the surface structure as TM migration became severe due to irreversible oxygen generation.

[0187] On the other hand, it was confirmed that the Spinel phase was hardly observed in the electrode of Example 1, which means that changes in the surface structure were suppressed due to a decrease in irreversible oxygen generation.

[0188]

[0189] Experimental Example 5: Thermal Stability Evaluation

[0190] Figure 7 is a graph showing the results of measuring electrodes manufactured according to Example 1 and Comparative Example 3 of the present invention using Differential Scanning Calorimeter (DSC).

[0191] The electrodes manufactured according to Example 1 and Comparative Example 3 were loaded into a differential scanning calorimeter and heated to 280°C at a heating rate of 10°C / min to check the thermal characteristics of the electrodes.

[0192] As shown in Fig. 7, it was confirmed that the electrode manufactured according to Example 1 of the present invention underwent an exothermic reaction at 284.7°C, and the electrode of Comparative Example 1 underwent an exothermic reaction at 175.8°C.

[0193] That is, it was confirmed that the electrode of Example 1 had superior thermal stability compared to Comparative Example 1 because the exothermic reaction occurred at a higher temperature in the electrode of Example 1 than in the electrode of Comparative Example 1.

[0194]

[0195] Experimental Example 6: Evaluation of Mechanical and Electrochemical Performance of Lithium Electrodes with Solid Electrolytes

[0196] The amount of electrolyte loaded into the electrode manufactured according to Example 1 and Comparative Example 3 and the electrode capacity were measured.

[0197] [Mathematical Formula 1]

[0198] Loading amount (mg / cm) 2 ) = electrode weight / electrode area

[0199] [Equation 2]

[0200] Electrode capacity (mAh / cm) 2 ) = electrode initial capacity (mAh / g) * electrode loading amount (mg / cm 2 )

[0201] Example 1 of the classification Comparative example 1 Electrode loading amount (mg / cm) 2 )(Mechanical properties)~ 40~ 10 Electrode capacity (mAh / cm 2 )(Electrochemical properties)~ 10~ 2.5

[0202] As shown in Table 2 above, it was confirmed that the electrode manufactured according to Example 1 of the present invention had a greater electrode loading amount and a significantly higher electrode capacity than Comparative Example 1.

[0203]

[0204] Experimental Example 7: Electrochemical Performance Evaluation of a Pouch-Type Battery with a Solid Electrolyte

[0205] Figure 8 shows the electrochemical performance of a pouch-type battery including an electrode manufactured according to Example 1 of the present invention.

[0206] As shown in Fig. 8, it was confirmed that the pouch-type battery including the electrode manufactured according to Example 1 exhibited an excellent energy density of 487 wh / kg.

[0207] In addition, it was confirmed that the pouch-type battery including the electrode manufactured according to Example 1 exhibited a coulombic efficiency of 98% or more, and that the capacity was stably maintained until the end of the 70th cycle.

[0208] Moreover, it was confirmed that the capacity was stably maintained up to the 100th cycle even when the cycled Li metal anode was replaced, which means that there was no problem with the anode structure.

[0209]

[0210] Above, embodiments of the present invention have been described, but those of ordinary skill in the art will be able to modify and change the present invention in various ways by adding, changing, deleting or adding components, etc., within the scope that does not depart from the spirit of the present invention described in the claims, and this will also be considered to be included within the scope of the rights of the present invention.

[0211] The present invention solves the problems of using a conventional excess lithium positive electrode, is structurally stable, and promotes interface stabilization, so that a solid electrolyte, an all-solid-state lithium secondary battery and a device including the same can be manufactured.

Claims

1. A core layer containing a liquid electrolyte; and A precursor composition for manufacturing a solid electrolyte of a lithium secondary battery including an excess lithium positive electrode, characterized in that it includes a shell layer surrounding the core layer as a cationic polymer.

2. A precursor composition for manufacturing a solid electrolyte, characterized in that the cationic polymer in the first paragraph is a compound represented by the following [structural formula 1]; [Structural formula 1] In the above structural formula 1, R1 and R3 are each independently primary to quaternary ammonium (-NH3 + , -NH2R` + , -NHR`2 + , -NR`3 + ), pyridinium (-Py + ), imidazolium (-Im + ), triazolium(-Trz + ), thiazolium (-Thz + ), phosphonium (e.g. -PR`3 + ), sulfonium (e.g. -SR`2 + ) or hydrazonium(-N2H5 + ) is a functional group of the series, wherein R` is a C1 to C4 alkyl group or an allyl group, The above R2 is tertiary ammonium or quaternary ammonium (-NR6R7- + ) and, The above R4 and R5 are each independently or And, The above R6 is , or and, The above R7 and R8 are each independently hydrogen, a C1 to C4 alkyl group or an allyl group, The above n1 to n7 are repeating unit numbers and are each independently an integer from 1 to 10.

3. In the second paragraph, in the above [structural formula 1], R1 and R3 are each independently primary to quaternary ammonium (-NH3 + , -NH2R` + , -NHR`2 + , -NR`3 + ) is a functional group of the series, wherein R` is a C1 to C4 alkyl group, The above R2 is quaternary ammonium (-NR6R7- + ) and, The above R4 and R5 are each independently And, The above R6 is , or and, The above R7 and R8 are each independently a C1 to C4 alkyl group, A precursor composition for manufacturing a solid electrolyte, characterized in that the above n1 to n7 are each independently an integer from 1 to 4 as a repeating unit number.

4. In the second paragraph, a precursor composition for manufacturing a solid electrolyte, characterized in that the compound represented by the above [structural formula 1] is a compound represented by any one of the following [chemical formulas 1] to [chemical formulas 3]; [Chemical Formula 1] [Chemical Formula 2] [Chemical Formula 3] .

5. A precursor composition for producing a solid electrolyte, characterized in that the cationic polymer in the first paragraph forms a pair with a counter anion of the cation.

6. In the fifth paragraph, the counter anion is N(SO2CF3)2 - (TFSI - ), N(COCF3)(SO2CF3) - , N(SO2F)2 - , N(CN)2 - , NO3 - , tetraphenylborate, BF4 - , B(CN)4 - , CH3BF3 - , CH2CHBF3 - , CF3BF3 - , C2F5BF3 - , n-C3F7BF3 - , n-C4F9BF3 - , PF7 - , CF3CO2 - , CF3SO3 - , C(CN)3 - , SCN - , SeCN - , CuCl2 - and AlCl4 - A precursor composition for manufacturing a solid electrolyte, characterized by being one selected from among:

7. A precursor composition for producing a solid electrolyte, characterized in that in paragraph 1, the solvent included in the liquid electrolyte is at least one selected from among ethylene carbonate (EC), propene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), ethyl acetate (EC), methyl propionate (MP), ethyl propionate (EP), and propyl propionate (PP).

8. A precursor composition for manufacturing a solid electrolyte, characterized in that the cationic polymer and the liquid electrolyte are mixed in a weight ratio of 1:2-15 in the first paragraph.

9. A precursor composition for manufacturing a solid electrolyte, characterized in that the excess lithium positive electrode in the first paragraph includes an excess lithium layered oxide (LLO, Layered Li-rich Manganese Oxides) represented by the following [chemical formula 4]; [Chemical Formula 4] Li 1+x Mn y M z O 2+w In the above chemical formula 1, x and w are each independently integers from 1 to 3, y and z are each independently 0.10 to 0.9, M additionally includes at least one selected from Ni, Al, Mg, Ti, Fe, and Nb.

10. A precursor composition for preparing a solid electrolyte, characterized in that the precursor composition for preparing a solid electrolyte in accordance with claim 1 does not contain a crosslinking agent.

11. A solid electrolyte for a lithium secondary battery including an excess lithium positive electrode, characterized in that the precursor composition for manufacturing a solid electrolyte selected from any one of claims 1 to 10 is cured by ultraviolet treatment.

12. Excess lithium anode; cathode; and An all-solid-state lithium secondary battery comprising a solid electrolyte of claim 11 positioned between the excess lithium positive electrode and negative electrode.

13. An all-solid-state lithium secondary battery according to claim 12, wherein the excess lithium positive electrode comprises an excess lithium-based layered oxide (LLO, Layered Li-rich Manganese Oxides) represented by the following [chemical formula 4]; [Chemical Formula 4] Li 1+x Mn y M z O 2+w In the above chemical formula 1, x and w are each independently integers from 1 to 3, y and z are each independently 0.10 to 0.9, M additionally includes at least one selected from Ni, Al, Mg, Ti, Fe, and Nb.

14. An all-solid-state lithium secondary battery, characterized in that in the 12th paragraph, the negative electrode is at least one selected from the group consisting of lithium metal, silicon-carbon composite, tin-based alloy, silicon, lithium titanate (LTO), soft carbon, hard carbon, and graphite.

15. Any one device selected from among portable electronic devices, mobile units, power devices, and energy storage devices containing the all-solid-state lithium secondary battery of Article 12.

16. A step of preparing a precursor composition for manufacturing a solid electrolyte according to clauses 1 to 10; and A method for producing a solid electrolyte for a lithium secondary battery including an excess lithium positive electrode, characterized in that it comprises a step of producing a polymer electrolyte by curing the precursor composition for producing the solid electrolyte with ultraviolet rays.

17. A method for manufacturing an all-solid-state lithium secondary battery, including a method for manufacturing a solid electrolyte according to Article 16.

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