KR20190080459A - Radiation gel-type electrolyte precursor composition, secondary battery and manufacturing method of the same - Google Patents

Abstract

The present invention relates to a radiation gel-type electrolyte precursor composition comprising: an organic electrolyte containing an ionic salt and an organic solvent; and a vinyl monomer and a polyfunctional vinyl crosslinking agent, and a secondary battery using the same and a method for manufacturing the same. The secondary battery of the present invention is excellent in safety.

Description

TECHNICAL FIELD [0001] The present invention relates to a radiation gel-type electrolyte precursor composition, a secondary battery, and a method for manufacturing the same. BACKGROUND ART [0002]

The present invention relates to a radiation gel-type electrolyte precursor composition, a secondary battery and a method for manufacturing the same.

A secondary battery refers to an energy storage device that can be repeatedly used while converting electrical energy into chemical energy (charging) and converting chemical energy into electrical energy (discharge) by an electrochemical oxidation / reduction reaction. The secondary cell is composed of an electrode, a separator, and an electrolyte, and in particular, the electrolyte is a core element of the cell safety.

 At present, the biggest problem of secondary batteries using liquid electrolyte is explosion risk due to impact and heat. In order to solve such a problem, development of a secondary battery using a gel electrolyte has been attempted.

Methods for manufacturing a secondary cell using the gel electrolyte developed to date include a method of manufacturing a gel electrolyte by using heat and light and assembling a secondary cell and a method of manufacturing a secondary battery using the gel electrolyte precursor composition. There is a method of manufacturing a secondary battery in which a gel electrolyte is applied through heat and light (UV) after assembly.

In the case of the electron method, a low performance due to an increase in interfacial resistance between the electrode and the electrolyte and a new manufacturing process design and development are required for industrial application, which makes it difficult to apply it to a commercial manufacturing process. Meanwhile, the latter method has an advantage that it can be directly applied to a currently used secondary cell manufacturing process unlike the former. However, since the heat and optical (UV) based gel forming method has the following problems, There is a limit.

 The heat-based gel formation method requires an initiator and has a low productivity at high temperature (≥ 70 ° C) for a long time (≥ 30 minutes) and has a problem of volume expansion of the battery due to volatilization of the electrolyte. A photoinitiator is required for a rapid gel formation, a long time is required when there is no photoinitiator, and fundamentally, there is a limit to be applied only to a cell having a thickness of less than a millimeter (≤ mm) due to a low penetration power of a UV light source.

 Therefore, in order to overcome such a problem, there is a need for a creative and new technical approach to manufacture a secondary battery using a gel electrolyte having the same level of performance as a conventional secondary battery using a conventional liquid electrolyte and without a change in commercial manufacturing process It is true.

Korean Patent Registration No. 10-0131460 (December 1, 1997)

The present invention utilizes radiation having a high penetration power and energy, and a secondary battery using a radiation gel-like electrolyte having a high degree of gelation and ionic conductivity at the same time without change of a commercial manufacturing process and without using an initiator, ), An organic electrolyte solution containing an ionic salt and an organic solvent, and a radiation gel-type electrolyte precursor composition comprising a vinyl monomer and a multifunctional vinyl crosslinking agent.

However, the technical problem to be solved by the present invention is not limited to the above-mentioned problems, and other matters not mentioned can be clearly understood by those skilled in the art from the following description.

The present invention provides a radiation gel-type electrolyte precursor composition comprising an organic electrolyte containing an ionic salt and an organic solvent, and a vinyl monomer and a multifunctional vinyl crosslinking agent.

According to an embodiment of the present invention, there is provided an electrode assembly including an anode, a cathode, and a separator; And a radiation gel-type electrolyte formed from a radiation gel-type electrolyte precursor composition comprising an organic electrolyte containing an ionic salt and an organic solvent, and a vinyl monomer and a polyfunctional vinyl crosslinking agent.

In another embodiment of the present invention, there is provided a process for preparing a radiation gel-type electrolyte precursor composition, which comprises: (a) preparing a radiation gel-type electrolyte precursor composition comprising an organic electrolyte containing an ionic salt and an organic solvent; and a vinyl monomer and a polyfunctional vinyl crosslinking agent; (b) an anode; A negative electrode and a separator, into a battery case; (c) injecting the radiation gel-type electrolyte precursor composition of step (a) into the battery case of step (b) and sealing the battery to form a secondary battery precursor; And (d) irradiating the secondary battery precursor of the step (c) with radiation.

The secondary battery to which the gel electrolyte according to the present invention is applied includes a radiation gel-type electrolyte formed from an organic electrolyte containing an ionic salt and an organic solvent, and a radiation gel-type electrolyte precursor composition comprising a vinyl monomer and a polyfunctional vinyl crosslinking agent A secondary battery employing a radiation gel electrolyte having a high gelation degree and an ionic conductivity at the same time without using a separate initiator and using a radiation having high permeability and energy, Gt; < = a few seconds). Accordingly, the secondary battery is characterized in that it has high safety while maintaining performance equivalent to that of a secondary battery using a conventional liquid electrolyte.

Further, in manufacturing the secondary battery, the secondary battery precursor assembled in a commercial manufacturing process was irradiated with a radiation continuous process facility (processing capacity: 1 M × 1 M area per 3 seconds) to demonstrate productivity. As a result, It was confirmed that the cylindrical secondary battery and the portable secondary battery can be manufactured at 480,000 and 360,000 times per hour, respectively, and it is expected that productivity of the commercial manufacturing process will not be affected even though the application of the radiation irradiation technique is applied.

In the future, the present invention can be applied not only to a lithium-graphite secondary battery which is currently commercialized but has low safety, but also to a secondary battery which has a low lifetime due to sulfur dissolution at the time of charging and discharging and is in a research and development stage of lithium- It is expected that the technical impact will be very great.

FIG. 1 is a schematic view illustrating a method of manufacturing a secondary battery using a radiation gel-like electrolyte according to an embodiment of the present invention. Referring to FIG.
2 is a photograph showing the gel formation of the electrolyte prepared in Example 1 (vs Comparative Example 3) and Example 6 (vs Comparative Example 4).
3 is a graph showing discharge capacities of the lithium secondary batteries manufactured in Examples 1 and 2. FIG.

The inventors of the present invention have studied a method of manufacturing a secondary battery using a gel electrolyte by utilizing radiation having high permeability and energy, and have found that an organic electrolyte containing an ionic salt and an organic solvent, an organic electrolyte containing a vinyl monomer and a polyfunctional vinyl When a radiation gel-type electrolyte precursor composition comprising a crosslinking agent is used, a secondary battery to which a radiation gel-type electrolyte having both high gelation degree and ionic conductivity at the same time is applied for a short time (≦ several seconds) And the present invention has been completed.

Hereinafter, the present invention will be described in detail.

radiation Gel type  Electrolyte precursor composition

The present invention provides a radiation gel-type electrolyte precursor composition comprising an organic electrolyte containing an ionic salt and an organic solvent, and a vinyl monomer and a multifunctional vinyl crosslinking agent.

The term " radiation gel-like electrolyte precursor composition "in the present specification means a precursor (pre-stage) material in which a colloidal solution (sol) becomes a gel electrolyte having a solid or more dense net structure formed by solidification to a certain concentration or higher, It means a state in which irradiation is required.

First, the radiation gel-type electrolyte precursor composition according to the present invention comprises an ionic salt and an organic electrolyte containing an organic solvent.

Wherein the ionic salt comprises a cation selected from the group consisting of Li ⁺ , Na ⁺ , K ^+, and NH ₄ ⁺ and a cation selected from the group consisting of ClO ₄ ^- , PF ₆ ^- , Cl ^- , I ^- , Br ^- , SCN ^- , CF ₃ SO ₃ ^{- _{BF 4 -, CF 3 CCl 3}} -, C 4 F 9 SO 3 -, AlO 2 -, AlCl 4 -, N (C x F 2x + 1 SO 2) (C y F 2y + 1 SO 2) (x and and y is a natural number) ^- , B (C ₂ O ₄ ) ₂ ^- . For example, the ionic salts are _{LiClO 4, LiPF 6, LiBF 4} , LiSbF 6, LiAsF 6, LiC 4 F 9 SO 3, LiAlO 2, LiAlCl 4, LiN (C x F 2x + 1 SO 2) (C y F _{2y + 1} SO ₂ ) (x and y are natural numbers), LiCl, LiI, and LiB (C ₂ O ₄ ) ₂ .

The organic solvent may be at least one selected from the group consisting of ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), vinylene carbonate (VC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate Is selected from the group consisting of methyl formate (MF), butyrolactone (? -BL), sulfolane, methylacetate (MA), and methyl propionate (MP) But is not limited thereto.

The concentration of the ionic salt in the organic electrolytic solution may be 0.1 M to 5.0 M. By using the organic electrolytic solution in such a concentration range, it is possible to produce a radiation gel-type electrolyte having an appropriate viscosity, It is possible to sufficiently dissolve and dissociate the salt salt, to enable effective migration of the cation, and to optimize the ionic conductivity of the radiation-gelled slice. When the concentration of the ionic salt in the organic electrolytic solution is less than 0.1 M, there is a problem that the ionic salt which dissolves and dissociates in the organic electrolytic solution is insufficient. When the concentration of the ionic salt in the organic electrolytic solution exceeds 5.0 M, There is a problem in that all the ionic salts can not be dissolved and dissociated. As a result, there is a problem that the ion conductivity of the radiation gel-like slice is lowered.

The vinyl monomer may be regarded as a precursor (pre-stage) material for interacting with the ionic salt in the organic electrolyte solution and cross-linking through the polyfunctional vinyl crosslinking agent upon irradiation with radiation.

Specifically, the vinyl monomer may be at least one selected from the group consisting of N-vinylpyrrolidone, N, N'-dimethylacrylamide, acrylonitrile, methyl methacrylate methyl methacrylate, vinyl acetate, acrylic acid, butyl acrylate, dimethylamino ethyl acrylate, and glycidyl methacrylate. ≪ / RTI >

Further, the vinyl-based monomer may include a polar functional group for interacting with the ionic salt, and the polar functional group is preferably a nitrogen-containing functional group including an amide group or a cyano group, but is not limited thereto. At this time, the amide group or the cyano group can be regarded as a functional group having high polarity due to nitrogen having a high electronegativity. By making the interaction with the ionic salt stronger, the ion conductivity of the radiation gel-like substrate can be optimized.

Specifically, the vinyl monomer may be at least one selected from the group consisting of N-vinylpyrrolidone, N, N'-dimethylacrylamide and acrylonitrile. But is not limited thereto.

The polyfunctional vinyl crosslinking agent is a crosslinking agent for forming a gel having a three-dimensional network structure upon irradiation with radiation. When a monofunctional vinyl crosslinking agent is used instead of the polyfunctional vinyl crosslinking agent, The single functional group does not function as a sufficient bridge, so that the gel having a three-dimensional network structure can not be formed properly.

Specifically, as the polyfunctional vinyl crosslinking agent, poly ethylene glycol diacrylate, poly propylene glycol diacrylate, tetraethylene glycol diacrylate, 1, But are not limited to, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, trimethylolpropane triacrylate, trimethylolpropane ethoxylate But are not limited to, trimethylolpropane ethoxylate triacrylate, trimethylolpropane propoxylate triacrylate, ditrimethylolpropane tetraacrylate, pentaerythritol tetraacrylate, pentaerythritol triacrylate, Ethoxylate tetra One selected from the group consisting of pentaerythritol ethoxylate tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate and triallyl isocyanurate (TAIC). Or more can be used.

More specifically, the polyfunctional vinyl crosslinking agent may include two or more acrylate groups, and the polyfunctional vinyl crosslinking agent is preferably a compound represented by the following formula (1), but is not limited thereto:

[Chemical Formula 1]

Wherein R is an ethylene group or a propylene group, and n is an integer of 10 to 1,000. If n is less than 10, the ionic conductivity of the gel is low, and the performance of the secondary battery is deteriorated. When n is more than 1,000, the viscosity is too high, which limits application to the actual process of the secondary battery.

The weight ratio of the organic electrolytic solution to the vinyl monomer and the polyfunctional vinyl crosslinking agent is preferably 70:30 to 95: 5, but is preferably 85:15 to 95: 5, but is not limited thereto. If the relative content of the organic electrolytic solution is too low, the ionic conductivity may be lowered due to excessive crosslinking, resulting in deterioration of the performance of the secondary battery. If the relative content of the organic electrolytic solution is too high, There is no problem.

The weight ratio of the vinyl monomer and the polyfunctional vinyl crosslinking agent may be 10:90 to 85:15, and is preferably 55:45 to 85:15, but is not limited thereto. If the relative content of the multifunctional vinyl crosslinking agent is too high, the ionic conductivity may be lowered due to excessive crosslinking, resulting in deterioration of the performance of the secondary battery. If the relative content of the multifunctional vinyl crosslinking agent is too low There is a problem that the gel is not formed properly.

Secondary battery

The present invention relates to an electrode assembly comprising a cathode, a cathode and a separator; And a radiation gel-type electrolyte formed from a radiation gel-type electrolyte precursor composition comprising an organic electrolyte containing an ionic salt and an organic solvent, and a vinyl monomer and a polyfunctional vinyl crosslinking agent.

The secondary battery may be a lithium secondary battery. Specifically, the lithium secondary battery may be a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery, a lithium ion polymer secondary battery, a lithium air secondary battery, But is not limited thereto.

Also, it is possible to provide a middle- or large-sized battery module or a battery pack including a plurality of the secondary batteries electrically connected to each other. The middle or large-sized battery module or the battery pack includes a power tool; An electric vehicle including an electric vehicle (EV), a hybrid electric vehicle (HEV), and a plug-in hybrid electric vehicle (PHEV); Electric truck; Electric commercial vehicle; Or a power storage system, as shown in FIG.

First, the secondary battery according to the present invention includes an electrode assembly including a cathode, a cathode, and a separator.

The electrode assembly includes a cathode, a cathode, and a separator. The cathode includes a cathode collector and a cathode active material. For example, LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , LiMn ₂ O ₄ , Li (Ni _a Co _b Mn _c ) O ₂ ( 0 <a <1, 0 < b <1, 0 <c <1, a + b + c = 1), LiNi 1 -y Co y O 2, LiCo 1 - y Mn y O 2, LiNi 1 - y Mn _y O ₂ (O <y <1), Li (Ni a Co b Mn c) O 4 (0 <a <2, 0 <b <2, 0 <c <2, a + b + c = 2), LiMn 2 - _z Ni _z O ₄ , LiMn _{2 - z} CozO ₄ (0 <z <2), LiCoPO ₄ and LiFePO ₄ . In addition to the lithium-containing transition metal oxide, sulfide, selenide and halide may be used.

The negative electrode comprises a negative electrode collector and a negative electrode active material. Specifically, examples of the positive electrode active material include a carbonaceous material, lithium-containing titanium composite oxide (LTO), which is capable of occluding and releasing lithium ions; Metals (Me) having Si, Sn, Li, Zn, Mg, Cd, Ce, Ni and Fe; An alloy composed of the metal (Me); An oxide of the metal (Me) (MeOx); And a composite of the metal (Me) and carbon may be used, and carbon materials such as low-crystalline carbon and highly-crystalline carbon are preferably used, but not limited thereto. Examples of low crystalline carbon are soft carbon and hard carbon. Examples of highly crystalline carbon include natural graphite, kish graphite, pyrolytic carbon, High temperature sintered carbon such as mesophase pitch based carbon fiber, meso-carbon microbeads, mesophase pitches and petroleum or coal tar pitch derived cokes. Meanwhile, the negative electrode may include a binder. Examples of the binder include polyvinylidene fluoride, polyacrylonitrile, vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), poly Methyl methacrylate, and the like can be used.

The separator may be fabricated using a fiber such as a nonwoven fabric made of a polyolefin material such as polyethylene, polypropylene, or polyvinylidene fluoride. In order to manufacture the separator, thermal bonding, airlay, wet, needle punching, Known methods such as spinning, spinning, spunbonding, meltblowing, stitching, and electrospinning can be used. On the other hand, the separation membrane may be a monolayer membrane or a multilayer membrane of two or more layers.

Next, the secondary battery according to the present invention comprises an organic electrolyte containing an ionic salt and an organic solvent, and a radiation gel-type electrolyte formed from a radiation gel-type electrolyte precursor composition comprising a vinyl monomer and a polyfunctional vinyl crosslinking agent.

The above-described radiation gel-type electrolyte is formed from the above-described radiation gel-type electrolyte precursor composition through irradiation with radiation. The above-described radiation gel-type electrolyte precursor composition has been described above, and a duplicate description will be omitted.

The gelation rate of the radiation gel-type electrolyte represented by the following formula (1) may be 90% or more:

[Equation 1]

Where W _dry is the initial dry weight of the radiation gel electrolyte and W _dissolved is the dry weight of the radiation gel gel electrolyte after extraction with an organic solvent at 50 for one week.

When the gelation rate of the radiation gel-type electrolyte is 90% or more, unlike a secondary battery using a conventional liquid electrolyte, there is an advantage of manufacturing a highly safe secondary battery by solving the risk of explosion due to impact and heat.

The radiation gel-like electrolyte may have an ionic conductivity sigma of 10 ^-4 mS / cm to 10 ^-2 mS / cm and a conductivity of 10 ^-3 mS / cm to 10 ^-2 mS / cm, But is not limited to:

&Quot; (2) &quot;

Where R is the bulk resistance measured by EIS, A is the area of SUS in contact with the radiation gel-like electrolyte, and 1 is the thickness of the radiation gel-like electrolyte.

By having a high ionic conductivity (in particular, 10 ^-3 excellent ionic conductivity in mS / cm to 10 ^-2 mS / cm range) in the radiation gel electrolyte is 10 ^-4 mS / cm to 10 ^-2 mS / cm range, It is possible to manufacture a secondary battery having a performance equivalent to that of a secondary battery manufactured through a practical commercial manufacturing process and using a conventional liquid electrolyte.

Manufacturing Method of Secondary Battery

The present invention provides a process for preparing a radiation gel-type electrolyte precursor composition, which comprises: (a) preparing a radiation gel-type electrolyte precursor composition comprising an organic electrolyte containing an ionic salt and an organic solvent, and a vinyl monomer and a polyfunctional vinyl crosslinking agent; (b) an anode; A negative electrode and a separator, into a battery case; (c) injecting the radiation gel-type electrolyte precursor composition of step (a) into the battery case of step (b) and sealing the battery to form a secondary battery precursor; And (d) irradiating the secondary battery precursor of the step (c) with radiation.

FIG. 1 is a schematic view illustrating a method of manufacturing a secondary battery using a radiation gel-like electrolyte according to an embodiment of the present invention. Referring to FIG.

As shown in FIG. 1, a secondary battery to which a radiation gel-type electrolyte according to an embodiment of the present invention is applied comprises: preparing the radiation gel-like electrolyte precursor composition; After the radiation gel-type electrolyte precursor composition is injected into a battery case charged with an electrode assembly including an anode, a cathode and a separator, the assembly is sealed to assemble a secondary battery precursor; And then irradiating the secondary battery precursor with radiation.

First, a method for producing a secondary battery according to the present invention comprises the steps of: (a) preparing a radiation gel-type electrolyte precursor composition comprising an organic electrolyte containing an ionic salt and an organic solvent, and a vinyl monomer and a polyfunctional vinyl crosslinking agent; Step].

Since the above-described radiation gel-type electrolyte precursor composition has been described above, a duplicate description will be omitted.

Next, a method of manufacturing a secondary battery according to the present invention includes: a positive electrode; A step (b) of injecting an electrode assembly including a cathode and a separator into a battery case, and a step of injecting the radiation gel-type electrolyte precursor composition into the battery case and then sealing to assemble the secondary battery precursor (c) Step].

Since the electrode assembly has been described above, redundant description will be omitted.

The battery case may have various shapes such as a cylindrical shape, a square shape, or a coin shape. The secondary battery precursor is in a state before the radiation gel-type electrolyte precursor composition is injected and sealed and irradiated with the radiation. The assembly of the precursor has the advantage that it can be assembled into a commercial manufacturing process.

Next, a method of manufacturing a secondary battery according to the present invention includes a step (d) of irradiating the secondary battery precursor with radiation.

The radiation has a high penetration power and energy. By utilizing the radiation, a secondary battery using a radiation gel-type electrolyte having both a high gelation degree and an ion conductivity at the same time without changing the commercial manufacturing process and using no initiator, (&Lt; = several seconds).

Specifically, the radiation may include at least one selected from the group consisting of an electron beam, a gamma ray and an X ray, and is preferably an electron ray in a short time irradiation aspect, but is not limited thereto. At this time, the total dose of the radiation may be 0.1 kGy to 20 kGy.

More specifically, when the electron beam is used as the radiation, an electron beam of 300 keV to 10 MeV may be used depending on the penetration depth of the secondary battery. In this case, when the pressure is less than 300 keV, the gel is difficult to form due to the limitation of the permeation depth. When the pressure is more than 10 MeV, the organic material may be completely different.

It is preferable that the electron beam is irradiated at a dose rate of 0.1 to 30 kGy / sec so that the total dose of the electron beam is 1 kGy to 20 kGy, but is not limited thereto. At this time, there is a problem that sufficient gel formation is not achieved at less than 1 kGy, and excessive gel formation at 20 kGy causes a problem of a rapid decrease in ion conductivity.

Meanwhile, when the gamma ray is used as the radiation, the gamma ray is preferably irradiated at a dose rate of 0.1 to 10 kGy / sec so that the total dose of the gamma ray is 0.1 kGy to 10 kGy. Do not. In this case, when the concentration is less than 0.1 kGy, there is a problem that sufficient gel formation is not performed. When the concentration exceeds 10 kGy, there is a problem in that the ion conductivity is drastically reduced due to excessive gel formation.

When the X-ray is used as the radiation, the X-ray is preferably irradiated at a dose rate of 0.1 to 10 kGy / sec so that the total dose of the X-ray is 0.1 kGy to 10 kGy. It is not limited. In this case, when the concentration is less than 0.1 kGy, there is a problem that sufficient gel formation is not performed. When the concentration exceeds 10 kGy, there is a problem in that the ion conductivity is drastically reduced due to excessive gel formation.

Accordingly, the secondary battery to which the gel electrolyte according to the present invention is applied includes a radiation gel-type electrolyte formed from an organic electrolyte containing ionic salt and organic solvent, and a radiation gel-type electrolyte precursor composition comprising a vinyl monomer and a polyfunctional vinyl crosslinking agent A secondary battery using a radiation gel electrolyte having a high degree of gelation and ionic conductivity at the same time without using a separate initiator and using a radiation having a high permeability and energy, It can be produced in-situ for a short time (≤ several seconds). Accordingly, the secondary battery is characterized in that it has high safety while maintaining performance equivalent to that of a secondary battery using a conventional liquid electrolyte.

Further, in manufacturing the secondary battery, the secondary battery precursor assembled in a commercial manufacturing process was irradiated with a radiation continuous process facility (processing capacity: 1 M × 1 M area per 3 seconds) to demonstrate productivity. As a result, It was confirmed that the cylindrical secondary battery and the portable secondary battery can be manufactured at 480,000 and 360,000 times per hour, respectively, and it is expected that productivity of the commercial manufacturing process will not be affected even though the application of the radiation irradiation technique is applied.

In the future, the present invention can be applied not only to a lithium-graphite secondary battery which is currently commercialized but has low safety, but also to a secondary battery which has a low lifetime due to sulfur dissolution at the time of charging and discharging and is in a research and development stage of lithium- It is expected that the technical impact will be very great.

Hereinafter, preferred embodiments of the present invention will be described in order to facilitate understanding of the present invention. However, the following examples are provided only for the purpose of easier understanding of the present invention, and the present invention is not limited by the following examples.

[ Example ]

Example  One

(1) Electron beam Gel type  Preparation of electrolyte precursor composition

As an organic solvent, an organic electrolytic solution was prepared by dissolving ethylene carbonate (EC): diethyl carbonate (DEC) having a volume ratio of 1: 1 in an amount of 1 M of LiClO ₄ as an ionic salt. (N-vinylpyrrolidone): poly (glycol) diacrylate (PEGDA) as a polyfunctional vinyl-based crosslinking agent at a weight ratio of 90: 8: 2 as a prepared organic electrolytic solution: To prepare an electron beam gel-type electrolyte precursor composition.

(2) Preparation of lithium secondary battery precursor

Using the electron beam gel-type electrolyte precursor composition prepared in (1), a lithium secondary battery precursor was prepared in the form of a coin cell.

Concretely, a cathode active material (LiCoO ₂ ): a conductive material (Denka black): a binder (PVDF) was uniformly mixed in a N 2 -methyl-2-pyrrolidone solvent in a weight ratio of 92.5: 3.5: 4.0, Uniformly pressed, pressed on a roll press, and vacuum dried in a vacuum oven of 100 for 12 hours to prepare a positive electrode. Next, a negative electrode active material (carbon powder, graphite): carbon black: binder (PVDF) was uniformly mixed in a N-methyl-2-pyrrolidone solvent in a weight ratio of 92.5: 3.5: 4.0, The foil was evenly applied, pressed on a roll press, and vacuum dried in a vacuum oven of 100 for 12 hours to prepare a negative electrode.

A nonwoven fabric made of polyethylene polypropylene (Namyang Nonwoven fabric, OCP22, thickness: 50 .mu.m) was used as the prepared positive electrode, the prepared negative electrode and separator, and the electron beam gel electrolyte precursor composition prepared in (1) was injected. Was prepared in the form of a coin cell according to a conventional manufacturing method.

On the other hand, in order to measure the ionic conductivity, the prepared anode and the prepared cathode were further prepared in the form of a coin cell in the same manner, except that the cathode was replaced with a SUS material.

(3) Production of lithium secondary battery by electron beam irradiation

Lithium secondary batteries were prepared by irradiating the lithium secondary battery precursors prepared in (2) with 2.5 MeV electron beams at dose rates of 2.5 mA, 20 m / min and 1 kGy / 3 sec. At this time, the total dose of electron beam was 1 kGy.

Example  2 to 20

A lithium secondary battery was produced in the same manner as in Example 1, except that the kind of the ionic salt, the kind of the vinyl monomer, and the total irradiation amount of the electron beam were changed as shown in Table 1 below.

Comparative Example  One

Except that the vinyl monomer and the multifunctional vinyl crosslinking agent were omitted from the electron beam gel-type electrolyte precursor composition and the separation membrane was changed to a polyethylene nonwoven fabric (NR420, 20 um) and electron beam irradiation was omitted, To prepare a lithium secondary battery.

Comparative Example  2

Except that the organic electrolytic solution was changed to an organic electrolytic solution obtained by dissolving the organic electrolytic solution in an ethylene carbonate (EC): diethyl carbonate (DEC) having a volume ratio of 1: 1 as an ionic salt such that LiPF ₆ had a concentration of 1M. 1, a lithium secondary battery was prepared.

Comparative Example  3

A lithium secondary battery was produced in the same manner as in Example 1, except that electron beam irradiation was omitted.

Comparative Example  4

A lithium secondary battery was produced in the same manner as in Example 6, except that electron beam irradiation was omitted.

Comparative Example  5

A lithium secondary battery was produced in the same manner as in Example 11, except that electron beam irradiation was omitted.

Comparative Example  6

A lithium secondary battery was produced in the same manner as in Example 16, except that electron beam irradiation was omitted.

Comparative Example  7

A lithium secondary battery was produced in the same manner as in Example 1, except that the weight ratio of the prepared organic electrolytic solution: vinyl monomer: polyfunctional vinyl crosslinking agent was changed to 80: 16: 4.

Comparative Example  8

A lithium secondary battery was produced in the same manner as in Example 5, except that the weight ratio of the organic electrolytic solution: vinyl monomer: polyfunctional vinyl crosslinking agent was changed to 90: 90: 1.

Comparative Example  9

A lithium secondary battery was produced in the same manner as in Example 1, except that the weight ratio of the organic electrolytic solution: vinyl monomer: polyfunctional vinyl crosslinking agent was changed to 90: 5: 5.

Electrolyte precursor composition anode cathode Membrane Total dose of electron beam
(kGy) Organic electrolyte Vinyl monomer Multifunctional vinyl-based crosslinking agent
(PEGDA) Kinds content
(wt%) Kinds content
(wt%) content
(wt%) Example 1 1 M LiClO ₄ in EC / DEC (1/1, v / v) 90 N-vinylpyrrolidone 8 2 LiCoO ₂ Graphite Non-woven
(OCP22, 50 [mu] M) One Example 2 90 8 2 2 Example 3 90 8 2 4 Example 4 90 8 2 8 Example 5 90 8 2 16 Example 6 1 M LiPF ₆ in EC / DEC
(1/1, v / v) 90 N, N'-dimethylacrylamide 8 2 LiCoO ₂ Graphite Non-woven
(OCP22, 50 [mu] M) One Example 7 90 8 2 2 Example 8 90 8 2 4 Example 9 90 8 2 8 Example 10 90 8 2 16 Example 11 1 M LiPF ₆ in EC / DEC
(1/1, v / v) 90 acrylonitrile 8 2 LiCoO ₂ Graphite Non-woven
(OCP22, 50 [mu] M) One Example 12 90 8 2 2 Example 13 90 8 2 4 Example 14 90 8 2 8 Example 15 90 8 2 16 Example 16 1 M LiPF ₆ in EC / DEC
(1/1, v / v) 90 메틸lacrylate 8 2 LiCoO ₂ Graphite Non-woven
(OCP22, 50 [mu] M) One Example 17 90 8 2 2 Example 18 90 8 2 4 Example 19 90 8 2 8 Example 20 90 8 2 16 Comparative Example 1 1 M LiClO ₄ in EC / DEC (1/1, v / v) 100 - - - LiCoO ₂ Graphite Membrane
(NR420, 20 [mu] M) - Comparative Example 2 1 M LiPF ₆ in EC / DEC
(1/1, v / v) 100 - - - LiCoO ₂ Graphite Membrane
(NR420, 20 [mu] M) - Comparative Example 3 1 M LiClO ₄ in EC / DEC (1/1, v / v) 90 N-vinylpyrrolidone 8 2 LiCoO ₂ Graphite Non-woven
(OCP22, 50 [mu] M) - Comparative Example 4 1 M LiPF ₆ in EC / DEC
(1/1, v / v) 90 N, N'-dimethylacrylamide 8 2 LiCoO ₂ Graphite Non-woven
(OCP22, 50 [mu] M) - Comparative Example 5 1 M LiPF ₆ in EC / DEC
(1/1, v / v) 90 acrylonitrile 8 2 LiCoO ₂ Graphite Non-woven
(OCP22, 50 [mu] M) - Comparative Example 6 1 M LiPF ₆ in EC / DEC
(1/1, v / v) 90 methylacrylate 8 2 LiCoO ₂ Graphite Non-woven
(OCP22, 50 [mu] M) - Comparative Example 7 1 M LiClO ₄ in EC / DEC (1/1, v / v) 80 N-vinylpyrrolidone 16 4 LiCoO ₂ Graphite Non-woven
(OCP22, 50 [mu] M) One Comparative Example 8 1 M LiClO ₄ in EC / DEC (1/1, v / v) 90 N-vinylpyrrolidone 9 One LiCoO ₂ Graphite Non-woven
(OCP22, 50 [mu] M) 16 Comparative Example 9 1 M LiClO ₄ in EC / DEC (1/1, v / v) 90 N-vinylpyrrolidone 5 5 LiCoO ₂ Graphite Non-woven
(OCP22, 50 [mu] M) One

* The organic electrolytes, vinyl monomers and multifunctional vinyl crosslinking agents used in Table 1 were all purchased from Aldrich, and both the positive and negative electrodes were purchased from MTI Korea.

Experimental Example  1: electron beam Gel type  Electrolytic Gelation rate  And ion conductivity measurement

(1) Electron beam Gel type  Electrolytic Gelation rate  Measure

In order to measure the gelation rates of the electrolytes prepared in Examples 1 to 20 and Comparative Examples 1 to 9, the electrolytes prepared in Examples 1 to 20 and Comparative Examples 1 to 9 were mixed at a volume ratio of 1: 1 for 50 to 1 week The gel was immersed in ethylene carbonate (EC): diethyl carbonate (DEC) to extract the unreacted material, and the gelation was observed. The gelation rate was calculated by the following formula (1) Are shown in Table 2 and Figure 2 below:

[Equation 1]

Where W _dry is the initial dry weight of the radiation gel electrolyte and W _dissolved is the dry weight of the radiation gel gel electrolyte after extraction with an organic solvent at 50 for one week.

Whether gel formation Gelation degree
( wt% ) Example  One ○ 95 Example  2 ○ 97 Example  3 ○ 100 Example  4 ○ 100 Example  5 ○ 100 Example  6 ○ 97 Example  7 ○ 100 Example  8 ○ 100 Example  9 ○ 100 Example  10 ○ 100 Example  11 ○ 90 Example  12 ○ 93 Example  13 ○ 98 Example  14 ○ 100 Example  15 ○ 100 Example  16 ○ 90 Example  17 ○ 95 Example  18 ○ 97 Example  19 ○ 100 Example  20 ○ 100 Comparative Example  One × 0 Comparative Example  2 × 0 Comparative Example  3 × 0 Comparative Example  4 × 0 Comparative Example  5 × 0 Comparative Example  6 × 0 Comparative Example  7 ○ 100 Comparative Example  8 × 0 Comparative Example  9 ○ 100

As shown in Table 2, unlike Comparative Examples 1 to 6 and 8, the electrolytes prepared in Examples 1 to 20 were confirmed to have a gelation rate of 90% or more at a total irradiation dose of 1 kGy and no additional initiator.

On the other hand, it was confirmed that the gel prepared in Comparative Examples 1 to 6 was not formed due to the electron beam irradiation. The electrolyte prepared in Comparative Example 8 was prepared by adjusting the weight ratio of the organic electrolytic solution, the vinyl monomer, and the polyfunctional vinyl crosslinking agent to 90: 9: 1. Since the relative content of the polyfunctional vinyl polymer was too small, Is not formed.

Also, as shown in Fig. 2, unlike Comparative Examples 3 and 4, the electrolytes prepared in Examples 1 and 6 clearly show that a complete gel does not flow.

(2) Electron beam Gel type  Measurement of ion conductivity of electrolyte

In order to measure ionic conductivities of the electrolytes prepared in Examples 1 to 20 and Comparative Examples 1 to 9, the lithium secondary batteries produced in Examples 1 to 20 and Comparative Examples 1 to 9 were subjected to electrochemical impedance spectroscopy (EIS ), And the ionic conductivity was calculated from Equation (2).

&Quot; (2) &quot;

Where R is the bulk resistance measured by EIS, A is the area of SUS in contact with the radiation gel-like electrolyte, and 1 is the thickness of the radiation gel-like electrolyte.

Ion conductivity
( mS / cm) Example  One 1.65 Example  2 1.50 Example  3 1.39 Example  4 1.17 Example  5 1.11 Example  6 1.58 Example  7 1.43 Example  8 1.25 Example  9 1.10 Example  10 1.06 Example  11 1.55 Example  12 1.42 Example  13 1.24 Example  14 1.09 Example  15 1.03 Example  16 0.160 Example  17 0.147 Example  18 0.121 Example  19 0.109 Example  20 0.103 Comparative Example  One 0.11 Comparative Example  2 0.14 Comparative Example  3 1.81 Comparative Example  4 1.69 Comparative Example  5 1.71 Comparative Example  6 1.73 Comparative Example  7 0.12 Comparative Example  8 1.11 Comparative Example  9 0.32

As shown in Table 3, the electrolytes prepared in Examples 1 to 20 were found to have excellent ionic conductivities in the range of 10 ^-4 mS / cm to 10 ^-2 mS / cm with a gelation rate of 90% or more. In particular, the electrolytes prepared in Examples 1 to 15 were prepared using an organic electrolytic solution, a vinyl-based monomer containing a polar functional group (an amide group or a cyano group) for interacting with an ionic salt, and a polyfunctional vinyl- , And it is confirmed to have a very good ionic conductivity in the range of 10 ^-3 mS / cm to 10 ^-2 mS / cm.

On the other hand, the electrolyte prepared in Comparative Example 7 was prepared by setting the weight ratio of the organic electrolytic solution, the vinyl monomer and the polyfunctional vinyl crosslinking agent to 80: 16: 4, and the relative content of the organic electrolytic solution was too low. . The electrolyte prepared in Comparative Example 9 was prepared by adjusting the weight ratio of the organic electrolytic solution, the vinyl monomer, and the polyfunctional vinyl crosslinking agent to 90: 5: 5. Since the relative content of the polyfunctional vinyl crosslinking agent was too high, It is confirmed that the conductivity is lowered. Therefore, it is considered that the electrolyte prepared in Comparative Examples 7 and 9 has a gelation rate of 90% or more, but it is difficult to apply it as a lithium secondary battery due to too low ionic conductivity.

Experimental Example  2: Evaluation of Discharge Capacity of Lithium Secondary Battery

In order to evaluate the discharge capacities of the lithium secondary batteries manufactured in Examples 1 and 2, discharge capacity evaluation was carried out at a charging and discharging current rate of 0.1 C at room temperature using a charge and discharge tester (wonAtech) Respectively.

As shown in Fig. 3, Examples 1 and 2 were confirmed to exhibit a discharge capacity (143 mAh / g) equivalent to that of a lithium secondary battery (liquid electrolyte application) in the form of a coin cell manufactured through an actual commercial manufacturing process . That is, although the lithium secondary batteries manufactured in Examples 1 and 2 were applied with gel electrolyte, they showed very rapid performance within seconds at room temperature without initiator. Although not shown in the drawing, it is confirmed that the lithium secondary batteries manufactured in Examples 3 to 20 (particularly, Examples 3 to 15) also have excellent discharge capacity.

It will be understood by those skilled in the art that the foregoing description of the present invention is for illustrative purposes only and that those of ordinary skill in the art can readily understand that various changes and modifications may be made without departing from the spirit or essential characteristics of the present invention. will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

Claims (16)

An organic electrolyte containing an ionic salt and an organic solvent,
A radiation gel-type electrolyte precursor composition comprising a vinyl-based monomer and a polyfunctional vinyl-based crosslinking agent.
The method according to claim 1,
Wherein the ionic salt comprises a cation selected from the group consisting of Li ⁺ , Na ⁺ , K ^+, and NH ₄ ⁺ and a cation selected from the group consisting of ClO ₄ ^- , PF ₆ ^- , Cl ^- , I ^- , Br ^- , SCN ^- , CF ₃ SO ₃ ^{- _{BF 4 -, CF 3 CCl 3}} -, C 4 F 9 SO 3 -, AlO 2 -, AlCl 4 -, N (C x F 2x + 1 SO 2) (C y F 2y + 1 SO 2) (x and and y is a natural number) ^- , B (C ₂ O ₄ ) ₂ ^-
Radiation gel type electrolyte precursor composition.
The method according to claim 1,
Wherein the concentration of the ionic salt in the organic electrolyte is from 0.1 M to 5.0 M
Radiation gel type electrolyte precursor composition.
The method according to claim 1,
Wherein the vinyl-based monomer comprises a polar functional group for interacting with the ionic salt
Radiation gel type electrolyte precursor composition.
5. The method of claim 4,
The polar functional group may be a nitrogen-containing functional group containing an amide group or a cyano group
Radiation gel type electrolyte precursor composition.
The method according to claim 1,
The vinyl monomer may be at least one selected from the group consisting of N-vinylpyrrolidone, N, N'-dimethylacrylamide and acrylonitrile.
Radiation gel type electrolyte precursor composition.
The method according to claim 1,
Wherein the polyfunctional vinyl crosslinking agent comprises two or more acrylate groups
Radiation gel type electrolyte precursor composition.
The method according to claim 1,
Wherein the polyfunctional vinyl-based crosslinking agent is a compound represented by the following formula
Radiation Gel Electrolyte Precursor Composition:
[Chemical Formula 1]

Wherein R is an ethylene group or a propylene group, and n is an integer of 10 to 1,000.
The method according to claim 1,
Wherein the weight ratio of the organic electrolytic solution to the vinyl monomer and the multifunctional vinyl crosslinking agent is 85:15 to 95: 5
Radiation gel type electrolyte precursor composition.
The method according to claim 1,
Wherein the weight ratio of the vinyl monomer and the polyfunctional vinyl crosslinking agent is 55:45 to 85:15
Radiation gel type electrolyte precursor composition.
An electrode assembly including an anode, a cathode, and a separator; And
Gel electrolyte comprising an organic electrolyte containing an ionic salt and an organic solvent, and a radiation gel-type electrolyte precursor composition comprising a vinyl monomer and a polyfunctional vinyl crosslinking agent,
Secondary battery.
12. The method of claim 11,
Wherein the radiation gel-type electrolyte has a gelation ratio of 90% or more as expressed by the following formula (1)
Secondary battery:
[Equation 1]

Where W _dry is the initial dry weight of the radiation gel electrolyte and W _dissolved is the dry weight of the radiation gel gel electrolyte after extraction with an organic solvent at 50 for one week.
12. The method of claim 11,
Wherein the radiation gel-like electrolyte has an ionic conductivity sigma of 10 &lt; ^-4 &gt; mS / cm to 10 &lt; ^-2 &gt; mS / cm,
Secondary battery:
&Quot; (2) &quot;

Where R is the bulk resistance measured by EIS, A is the area of SUS in contact with the radiation gel-like electrolyte, and 1 is the thickness of the radiation gel-like electrolyte.
(a) preparing a radiation gel-type electrolyte precursor composition comprising an organic electrolyte containing an ionic salt and an organic solvent, and a vinyl monomer and a polyfunctional vinyl crosslinking agent;
(b) an anode; A negative electrode and a separator, into a battery case;
(c) injecting the radiation gel-type electrolyte precursor composition of step (a) into the battery case of step (b) and sealing the battery to form a secondary battery precursor; And
(d) irradiating the secondary battery precursor of the step (c) with radiation
A method of manufacturing a secondary battery.
15. The method of claim 14,
In the step (d), the radiation may include at least one selected from the group consisting of electron beam, gamma ray and X ray
A method of manufacturing a secondary battery.
15. The method of claim 14,
In the step (d), the total dose of radiation is 0.1 kGy to 20 kGy
A method of manufacturing a secondary battery.

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