Secondary battery electrode coated with organic active material, secondary battery comprising same, and method for manufacturing same

Abstract

The present invention relates to a secondary battery electrode, a secondary battery comprising same, and a method for manufacturing same. More specifically, the present invention relates to a secondary battery electrode coated with an organic active material, a secondary battery comprising same, and a method for manufacturing same.

Description

Electrode for a secondary battery coated with an organic active material, a secondary battery including the same, and a method for manufacturing the same

[0001] The present invention relates to an electrode for a secondary battery, a secondary battery including the same, and a method for manufacturing the same. More specifically, the present invention relates to an electrode for a secondary battery coated with an organic active material, a secondary battery including the same, and a method for manufacturing the same.

[0002] As wireless communication technology advances, there is a growing demand for lighter, thinner, and smaller portable devices and automotive components, leading to an increased need for rechargeable batteries to serve as the energy source for these devices. In particular, with the commercialization of hybrid and electric vehicles aimed at preventing environmental pollution, research is emerging to utilize rechargeable batteries in these next-generation vehicles to reduce manufacturing costs and weight while extending lifespan.

[0003] Generally, a lithium secondary battery is manufactured by mounting an electrode assembly, composed of a negative electrode, a positive electrode, and a separator, inside a pouch-type case made of a metal can (such as a cylindrical or prismatic) or an aluminum laminate sheet, and injecting an electrolyte into the electrode assembly.

[0004] However, conventional lithium secondary batteries pose a risk of fire and explosion due to liquid electrolyte leakage, and have the problem of low energy density due to the inclusion of liquid electrolytes and separators.

[0005] To address these issues, research is being conducted on secondary batteries using solid-state electrolytes. However, the process of manufacturing an all-solid-state battery by separately producing the electrode and the solid-state electrolyte and then stacking them is complex and has the disadvantage of causing side reactions due to residual moisture between the electrode and the solid-state electrolyte.

[0006] To address these drawbacks, research is needed to simplify the battery manufacturing process and reduce the interfacial resistance between the electrode and the electrolyte.

[0007] [Prior Art Literature]

[0008] [Patent Literature]

[0009] (Patent Document 1) Republic of Korea Published Patent No. 10-2019-0036724

[0010] Accordingly, the inventors conducted multifaceted research to solve the above problem and, as a result, manufactured a secondary battery by applying a mixed slurry containing an organic active material containing free radicals and a solvent to an electrode, evaporating the solvent to produce a composite film from which the solvent has been removed, absorbing a liquid electrolyte into the composite film, and covering it with an opposite electrode.

[0011] Accordingly, the present invention aims to provide a secondary battery with improved lifespan characteristics by using an organic active material containing free radicals.

[0012] In addition, the present invention aims to provide a secondary battery with excellent characteristics and electrochemical performance by using an organic active material containing free radicals to increase the adhesion between the electrode and the separator and thereby reducing the interfacial resistance between the electrode and the separator.

[0013] In addition, the present invention aims to provide a method for manufacturing a secondary battery with reduced costs by simplifying the battery manufacturing process.

[0014] In order to solve the aforementioned problem,

[0015] In one embodiment of the present invention, a method for manufacturing a secondary battery is provided, comprising the following steps:

[0016] (a) a step of preparing a mixed slurry comprising an organic active material containing a radical and a solvent,

[0017] (b) a step of applying the mixed slurry prepared in step (a) to one of the electrodes, then drying and heat-treating to remove the solvent and forming a composite film,

[0018] (c) a step of manufacturing an electrode unit in which the electrode and the electrolyte are integrated by absorbing a liquid electrolyte into the composite film formed in step (b) above, and

[0019] (d) A step of stacking the opposite electrode onto the electrode unit manufactured in step (c).

[0020] In one embodiment of the present invention, a method for manufacturing a secondary battery provides a method comprising the following steps: a first mixed slurry comprising a first organic active material comprising a nitroxyl radical and a solvent; and a second mixed slurry comprising a second organic active material different from the first organic active material and a solvent.

[0021] In one embodiment of the present invention, a method for manufacturing a secondary battery provides a method comprising the following steps: applying a first mixed slurry to one of the electrodes, applying a second mixed slurry over the applied first mixed slurry, and then simultaneously drying and heat-treating to remove the solvent and forming a first composite film and a second composite film.

[0022] In one embodiment of the present invention, a method for manufacturing a secondary battery provides a method comprising the following steps: absorbing a liquid electrolyte into a first composite film and a second composite film to manufacture an electrode unit in which an electrode and a multilayer electrolyte are integrated.

[0023] In one embodiment of the present invention, a method for manufacturing a secondary battery is provided by applying a first mixed slurry containing an organic active material containing a radical and a solvent to one of the first electrodes, then heat treating and drying to remove the solvent and forming a first composite film, and absorbing a liquid electrolyte into the formed first composite film to manufacture a first electrode unit in which the first electrode and the electrolyte are integrated, and simultaneously or sequentially, applying a second mixed slurry different from the first mixed slurry to one of the second electrodes, then heat treating and drying to remove the solvent and forming a second composite film, and absorbing a liquid electrolyte into the formed second composite film to manufacture a second electrode unit in which the second electrode and the electrolyte are integrated, and stacking the manufactured first electrode unit and the second electrode unit.

[0024] At this time, the organic active material is a compound having free radicals within its polymer molecular structure, and may be a polymer containing a nitroxide radical, a polymer containing a sulfonyloxy radical, or a polymer containing a phenoxyl radical.

[0025] Polymers containing nitroxide radicals include compounds containing a TEMPO group of Chemical Formula 1, compounds containing a proxyl group of Chemical Formula 2, compounds containing a 1,1,3,3-tetramethyl-isoindolin-2-yloxyl(1,1,3,3-tetramathyl-isoindolin-2-yloxyl) group of Chemical Formula 3, and compounds containing an N-tert-butyl-N-oxylaminophenyl (N-tert-butyl-N-oxylaminophenyl) group of Chemical Formula 4.

[0026] [Chemical Formula 1]

[0027]

[0028] [Chemical Formula 2]

[0029]

[0030] [Chemical Formula 3]

[0031]

[0032] [Chemical Formula 4]

[0033]

[0034] Specific examples of polymers containing nitroxide radicals include PTMA (poly(2,2,6,6-tetramethylpiperidinyloxy-4-ylmethacrylate)) of the following chemical formula 5, PTVE (poly(2,2,6,6-tetramethylpiperidine-4-yl-1-oxyl vinyl ether)) of the following chemical formula 6, and PTNB (poly[2,3-bis(2,2,6,6-tetramethylpiperidine-N-oxycarbonyl)-norbornene]) of the following chemical formula 7.

[0035] [Chemical Formula 5]

[0036]

[0037] (n is 5 to 1000)

[0038] [Chemical Formula 6]

[0039]

[0040] (n is 5 to 1000)

[0041] [Chemical Formula 7]

[0042]

[0043] (n is 5 to 1000)

[0044] Specific examples of polymers containing sulfonylooxy radicals include PSS (poly(4-styrenesulfonate)) of chemical formula 8.

[0045] [Chemical Formula 8]

[0046]

[0047] (n is 5 to 1000)

[0048] Specific examples of polymers containing phenoxyl radicals include substances containing a phenoxyl group of Chemical Formula 9 and substances containing a tetramethylphenoxyl group of Chemical Formula 10. Polymers having phenoxyl radicals can have 5 to 1,000 repeating units.

[0049] [Chemical Formula 9]

[0050]

[0051] [Chemical Formula 10]

[0052]

[0053] The polymer having the above-mentioned nitroxide radical can be used as both the anode and the cathode. The polymer having the above-mentioned sulfonyloxide radical and the polymer having the above-mentioned phenoxyl radical can be used as the cathode.

[0054] In one embodiment of the present invention, a method for manufacturing a secondary battery is provided, wherein the thickness of the composite film formed in step (b) is 100 nm to 1000 nm.

[0055] In one embodiment of the present invention, a method for manufacturing a secondary battery is provided in which the viscosity ratio of the first mixed slurry and the second mixed slurry is 1:10 to 10:1.

[0056] In one embodiment of the present invention, a method for manufacturing a secondary battery is provided in which the solvent is N-methyl-2-pyrrolidone (NMP)-based or its derivative, acetone-based or its derivative, alcohol-based or its derivative, methanol-based or its derivative, dimethylacetamide (DMAc)-based or its derivative, tetrahydrofuran (THF)-based or its derivative, dimethylformamide (DMF)-based or its derivative, distilled water, or a mixture thereof.

[0057] In one embodiment of the present invention, a method for manufacturing a secondary battery is provided in which the content of the liquid electrolyte is 1 to 30 weight% based on the total weight of the composite film.

[0058] In one embodiment of the present invention, a method for manufacturing a secondary battery is provided, wherein the liquid electrolyte is a lithium salt or sodium salt dissolved in a non-aqueous organic solvent, an ionic liquid solvent, or a mixture thereof.

[0059] In one embodiment of the present invention, a method for manufacturing a secondary battery is provided in which the non-aqueous organic solvent is a carbonate-based, ester-based, ether-based, ketone-based, alcohol-based, aprotic solvent, or a combination thereof.

[0060] In one embodiment of the present invention, the ionic liquid solvent is an imidazolium-based, pyridinium-based, pyrrolidinium-based, sulfonium-based, pyrazolium-based, ammonium-based, morpholinium-based, phosphonium-based, piperidinium-based, or a combination thereof, and provides a method for manufacturing a secondary battery.

[0061] In one embodiment of the present invention, a method for manufacturing a secondary battery is provided in which the lithium salt is LiClO4, LiPF6, CF3SO2NLiSO2CF3(LiTFSI), Li[N(SO2F)2](LiFSI), Li[B(C2O4)2](LiBOB), LiAsF6, lithium fluorosulfonyl-trifluoromethanesulfonylimide (LiFTFSI), or a combination thereof.

[0062] In one embodiment of the present invention, a method for manufacturing a secondary battery is provided in which the sodium salt is NaClO4, NaPF4, NaPF6, NaAsF6, NaTFSI, Na[(C2F5)3PF3](NaFAP), Na[B(C2O4)2](NaBOB), Na[N(SO2F)2](NaFSI), NaBeti(NaN[SO2C2F5]2) or a combination thereof.

[0063] In one embodiment of the present invention, a secondary battery manufactured by the method for manufacturing the secondary battery is provided.

[0064] According to the present invention, the manufacturing process of a secondary battery is simplified, providing economic advantages.

[0065] In addition, the secondary battery according to one embodiment of the present invention has the effect of improving the characteristics and electrochemical performance of the battery by improving the adhesion between the electrode and the separator, thereby lowering the interfacial resistance.

[0066] The present invention is capable of various modifications and may have various embodiments, and specific embodiments are to be described in detail in the detailed description.

[0067] However, this is not intended to limit the invention to specific embodiments, and it should be understood that it includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention.

[0068] In the present invention, terms such as "comprising" or "having" are intended to specify the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not excluding in advance the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0069] Furthermore, in the present invention, when a part such as a layer, film, region, or plate is described as being "on" another part, this includes not only cases where it is "immediately above" the other part, but also cases where there is another part in between. Conversely, when a part such as a layer, film, region, or plate is described as being "under" another part, this includes not only cases where it is "immediately below" the other part, but also cases where there is another part in between. Additionally, in the present application, being "placed on" may include cases where it is placed on the lower part as well as on the upper part.

[0070] Conventional secondary batteries are manufactured by producing units such as electrodes and electrolytes separately through independent processes and then stacking them. This manufacturing process is not only time-consuming but also complex. Furthermore, when electrodes and electrolytes are manufactured independently and then stacked, adverse reactions caused by residual moisture between the electrodes and electrolytes occur, leading to increased interfacial resistance and a degradation of ion conductivity and battery characteristics.

[0071] Accordingly, the present invention aims to provide an electrode coated with an organic active material and a method for manufacturing the same, which can improve the characteristics of the battery and the electrochemical performance of the battery by simplifying the battery manufacturing process and reducing the interfacial resistance between the electrode and the electrolyte.

[0072] The present invention will be described in more detail below.

[0073] In one embodiment of the present invention, a method for manufacturing a secondary battery may include the following steps:

[0074] (a) a step of preparing a mixed slurry comprising an organic active material containing a nitroxyl radical and a solvent;

[0075] (b) a step of applying the mixed slurry prepared in step (a) to one of the electrodes, then drying and heat-treating to remove the solvent and forming a composite film;

[0076] (c) a step of manufacturing an electrode unit in which the electrode and the electrolyte are integrated by absorbing a liquid electrolyte into the composite film formed in step (b) above; and

[0077] (d) A step of stacking the opposite electrode onto the electrode unit manufactured in step (c).

[0078] Step (a) above is a step of preparing a slurry to be applied to an electrode to form a composite film. The slurry may be a slurry prepared by mixing an organic active material and a solvent.

[0079] In one embodiment of the present invention, the organic active material is an organic material containing a nitroxyl radical, and the organic active material may exhibit an electrochemical oxidation-reduction reaction through interaction with a cation or anion in the electrolyte. By manufacturing an electrode coated with the organic active material, the adhesion between the separators increases, thereby reducing the interfacial resistance. Additionally, by manufacturing an electrode coated with the organic active material containing the free radical, the reversible capacity increases.

[0080] At this time, the organic active material is a compound having free radicals within its polymer molecular structure, and may be a polymer containing a nitroxide radical, a polymer containing a sulfonyloxy radical, or a polymer containing a phenoxyl radical.

[0081] Polymers containing nitroxide radicals include compounds containing a TEMPO group of Chemical Formula 1, compounds containing a proxyl group of Chemical Formula 2, compounds containing a 1,1,3,3-tetramethyl-isoindolin-2-yloxyl(1,1,3,3-tetramathyl-isoindolin-2-yloxyl) group of Chemical Formula 3, and compounds containing an N-tert-butyl-N-oxylaminophenyl (N-tert-butyl-N-oxylaminophenyl) group of Chemical Formula 4.

[0082] [Chemical Formula 1]

[0083]

[0084] [Chemical Formula 2]

[0085]

[0086] [Chemical Formula 3]

[0087]

[0088] [Chemical Formula 4]

[0089]

[0090] Specific examples of polymers containing nitroxide radicals include PTMA (poly(2,2,6,6-tetramethylpiperidinyloxy-4-ylmethacrylate)) of the following chemical formula 5, PTVE (poly(2,2,6,6-tetramethylpiperidine-4-yl-1-oxyl vinyl ether)) of the following chemical formula 6, and PTNB (poly[2,3-bis(2,2,6,6-tetramethylpiperidine-N-oxycarbonyl)-norbornene]) of the following chemical formula 7.

[0091] [Chemical Formula 5]

[0092]

[0093] (n is 5 to 1000)

[0094] [Chemical Formula 6]

[0095]

[0096] (n is 5 to 1000)

[0097] [Chemical Formula 7]

[0098]

[0099] (n is 5 to 1000)

[0100] Specific examples of polymers containing sulfonylooxy radicals include PSS (poly(4-styrenesulfonate)) of chemical formula 8.

[0101] [Chemical Formula 8]

[0102]

[0103] (n is 5 to 1000)

[0104] Specific examples of polymers containing phenoxyl radicals include substances containing a phenoxyl group of Chemical Formula 9 and substances containing a tetramethylphenoxyl group of Chemical Formula 10. Polymers having phenoxyl radicals can have 5 to 1,000 repeating units.

[0105] [Chemical Formula 9]

[0106]

[0107] [Chemical Formula 10]

[0108]

[0109] The polymer having the above-mentioned nitroxide radical can be used as both the anode and the cathode. The polymer having the above-mentioned sulfonyloxide radical and the polymer having the above-mentioned phenoxyl radical can be used as the cathode.

[0110] The compound of Chemical Formula 1-7 above is a polymer containing nitroxyl radicals, and when the battery is charged, the nitroxide radical moiety is converted into an oxoammonium cation, and when the battery is discharged, the oxoammonium cation is converted back into a nitroxide radical in two stages, finally producing an aminooxy anion.

[0111] In one embodiment of the present invention, in the case of the compound of Formula 5, when the cut-off voltage during discharge is 3.0V, the reaction equation of step 1, that is, the oxoammonium cation is converted into a nitroxide radical, thereby realizing a theoretical capacity of 110 mAh / g. When the discharge cut-off voltage is 1.5V, both stages of discharge occur, thereby realizing a theoretical capacity of 220 mAh / g.

[0112] When a polymer containing sulfonyloxy radicals is used as the cathode, during charging, the sulfonyloxy radicals gain electrons to become sulfonyloxy anions, and during discharging, the sulfonyloxy anions lose electrons to become sulfonyloxy radicals.

[0113] When a polymer containing phenoxyl radicals is used as the cathode, the phenoxyl radicals lose electrons during discharge to become phenoxyl cations, and during charging, the phenoxyl cations gain electrons to become phenoxyl radicals.

[0114] In one embodiment of the present invention, the above formula 1 can be converted and used as a compound of the following formula 11.

[0115] [Chemical Formula 11]

[0116]

[0117] In the above chemical formula 11, TEMPO(2,2,6,6-tetramethyl-1-piperidinyloxy) supported on a polymer is a compound in which one or more TEMPO residues are bonded to an organic or inorganic polymer support R.

[0118] TEMPO supported by the polymer of Chemical Formula 11 above is a compound in which one or more TEMPO residues are bonded to an organic or inorganic polymer support. The organic or inorganic polymer is bonded to the TEMPO residue at the R position. At this time, R may be any one of an organic polymer such as polystyrene, polyacrylate, polymethacrylate, polyacrylamide, polyvinyl ether containing a C=O group, polyether containing a C=O group, polynorbornene containing a C=O group, and polyethylene glycol containing a C=O group, an inorganic polymer such as silica containing a C=O group, a copolymer of these organic polymers, or a copolymer of these organic polymers and an inorganic polymer.

[0119] The organic active materials of the above chemical formulas 1 to 11 have a fast electrochemical reaction rate, making high-speed charging easy, and the output is more than 3 times better than that of conventional lithium secondary batteries.

[0120] In one embodiment of the present invention, the solvent used in the preparation of the mixed slurry may be a substance that dissolves an organic active material. More specifically, the solvent may be an N-methyl-2-pyrrolidone (NMP) system or its derivative, an acetone system or its derivative, an alcohol system or its derivative, a methanol system or its derivative, a dimethylacetamide (DMAc) system or its derivative, a tetrahydrofuran (THF) system or its derivative, a dimethylformamide (DMF) system or its derivative, distilled water, or a mixture thereof, but is not limited to these examples.

[0121] Step (b) above is a step of forming a composite film on an electrode by applying a mixed slurry to the electrode. The composite film may be a coating layer formed by applying a slurry containing an organic active material onto the electrode and removing the solvent.

[0122] In one embodiment of the present invention, the thickness of the composite film may be 100 nm to 1000 nm. More specifically, the thickness of the composite film formed in step (b) above may be 100 nm or more, 120 nm or more, 140 nm or more, 160 nm or more, 180 nm or more, 200 nm or more, 220 nm or more, 240 nm or more, 260 nm or more, 280 nm or more, 300 nm or more, 320 nm or more, 340 nm or more, 360 nm or more, 380 nm or more, 400 nm or more, or 1000 nm or less, 980 nm or less, 960 nm or less, 940 nm or less, 920 nm or less, 900 nm or less, 880 nm or less, 860 nm or less, 840 nm or less, 820 nm or less, 800 nm or less, 780 nm or less, 760 nm or less, 740 nm or less, 720 nm or less, 700 nm or less, but the It is not limited only to the scope.

[0123] If the thickness of the above composite film is less than 100 nm or more than 1000 nm, there is a problem in that the adhesion between the electrode and the separator decreases, and the interfacial resistance increases, thereby degrading the battery performance.

[0124] The above step (c) is a step of manufacturing an electrode unit in which the electrode and the electrolyte are integrated without forming a separate electrolyte layer by absorbing a liquid electrolyte into a composite film.

[0125] In one embodiment of the present invention, the liquid electrolyte may be a lithium salt or sodium salt dissolved in a non-aqueous organic solvent, an ionic liquid solvent, or a mixture thereof.

[0126] The above-mentioned non-aqueous organic solvent may be a carbonate-based, ester-based, ether-based, ketone-based, alcohol-based, aprotic solvent, or a combination thereof.

[0127] The above ionic liquid solvent may be imidazolium, pyridinium, pyrrolidinium, sulfonium, pyrazolium, ammonium, morpholinium, phosphonium, piperidinium, or a combination thereof.

[0128] The lithium salt may be LiClO4, LiPF6, CF3SO2NLiSO2CF3(LiTFSI), Li[N(SO2F)2](LiFSI), Li[B(C2O4)2](LiBOB), LiAsF6, lithium fluorosulfonyl-trifluoromethanesulfonylimide (LiFTFSI), or a combination thereof.

[0129] The above sodium salt may be NaClO4, NaPF4, NaPF6, NaAsF6, NaTFSI, Na[(C2F5)3PF3](NaFAP), Na[B(C2O4)2](NaBOB), Na[N(SO2F)2](NaFSI), NaBeti(NaN[SO2C2F5]2) or a combination thereof.

[0130] In one embodiment of the present invention, the content of the liquid electrolyte may be 1 to 30 weight% based on the total weight of the composite film. More specifically, the content of the liquid electrolyte may be 1 weight% or more, 2 weight% or more, 3 weight% or more, 4 weight% or more, 5 weight% or more, 6 weight% or more, 7 weight% or more, 8 weight% or more, 9 weight% or more, 10 weight% or more based on the total weight of the composite film, or 30 weight% or less, 29 weight% or less, 28 weight% or less, 27 weight% or less, 26 weight% or less, 25 weight% or less, 24 weight% or less, 23 weight% or less, 22 weight% or less, 21 weight% or less, 20 weight% or less, but is not limited to these ranges.

[0131] If the content of the above liquid electrolyte is less than 1 weight % or more than 30 weight % based on the total weight of the composite, there is a problem in that the characteristics of the battery are degraded due to a decrease in ion conductivity.

[0132] The above step (d) is a step of manufacturing a secondary battery by stacking a counter electrode on an electrode unit in which the electrode and the electrolyte are integrated. Here, a step of further including a separator between the electrode unit and the counter electrode may be included.

[0133] In one embodiment of the present invention, the secondary battery may include an electrode unit in which an electrode comprising a multilayer composite film and an electrolyte are integrated. The multilayer composite film may be manufactured by continuously applying a first mixed slurry and a second mixed slurry onto the electrode, and then drying and heat-treating to remove the solvent.

[0134] In order to manufacture a secondary battery comprising an electrode unit in which an electrode and an electrolyte are integrated, the above steps (a) to (c) may each include the following steps.

[0135] The above step (a) may include the step of preparing a first mixed slurry comprising a first organic active material containing a nitroxyl radical and a solvent; and a second mixed slurry comprising a second organic active material different from the first organic active material and a solvent.

[0136] Since the description of the previously mentioned organic active material can be applied identically to the first and second organic active materials mentioned above, redundant content is omitted.

[0137] Controlling the viscosity of the mixed slurry in the manufacturing process of an electrode including a multilayer composite film can affect the performance of the battery.

[0138] In one embodiment of the present invention, the viscosity ratio of the first mixed slurry and the second mixed slurry may be 1:10 to 10:1. More specifically, the viscosity ratio of the first mixed slurry and the second mixed slurry may be 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, 1:5.5, 1:6, 1:6.5, 1:7, 1:7.5, 1:8, 1:8.5, 1:9, 1:9.5, 1:10, or 10:1, 9.5:1, 9:1, 8.5:1, 8:1, 7.5:1, 7:1, 6.5:1, 6:1, 5.5:1, 5:1, 4.5:1, 4:1, 3.5:1, 3:1, 2.5:1, 2:1, but is limited to these ratios. It is not.

[0139] When forming the above multilayer composite film, if the viscosity ratio of the first mixed slurry and the second mixed slurry deviates from the range of 1:10 to 10:1, there is a problem in that the degree of dispersion of the organic active material is reduced, and the performance of the battery is degraded.

[0140] The above step (b) may include the step of applying a first mixed slurry to one of the electrodes, applying a second mixed slurry over the applied first mixed slurry, and then simultaneously drying and heat-treating to remove the solvent and forming a first composite film and a second composite film.

[0141] In the above step, the total thickness of the first composite film and the second composite film may be 100 nm to 1000 nm. That is, even if a multilayer composite film is formed, it is the same as the range of the total thickness of the composite film described in the description of step (b).

[0142] The above step (c) may include the step of manufacturing an electrode unit in which the electrode and the multilayer electrolyte are integrated by absorbing a liquid electrolyte into the first composite film and the second composite film.

[0143] Since the description of the liquid electrolyte mentioned earlier applies equally to the above liquid electrolyte, redundant details are omitted.

[0144] In one embodiment of the present invention, the secondary battery may each include a positive electrode unit and a negative electrode unit in which an electrode including a composite film and an electrolyte are integrated.

[0145] In one embodiment of the present invention, a first mixed slurry comprising an organic active material containing a nitroxyl radical and a solvent is applied to one of the first electrodes, and then heat-treated and dried to remove the solvent and form a first composite film, and a liquid electrolyte is absorbed into the formed first composite film to manufacture a first electrode unit in which the first electrode and the electrolyte are integrated.

[0146] At the same time or sequentially, a second mixed slurry different from the first mixed slurry is applied to one of the second electrodes, then heat-treated and dried to remove the solvent and form a second composite film, and a liquid electrolyte is absorbed into the formed second composite film to manufacture a second electrode unit in which the second electrode and the electrolyte are integrated.

[0147] A secondary battery can be manufactured by stacking the first electrode unit and the second electrode unit manufactured above.

[0148] When the above secondary battery includes a positive electrode unit and a negative electrode unit, the electrical stability and characteristics at each electrode are excellent, so it can exhibit superior battery characteristics compared to a secondary battery including only one electrode unit.

[0149] The present invention will be explained in more detail below through examples and experimental examples.

[0150] However, the following examples and experimental examples are merely illustrative of the present invention, and the content of the present invention is not limited to the following examples and experimental examples.

[0151] The present invention relates to manufacturing an integrated all-solid-state battery by applying a mixed slurry containing an organic active material and a solvent to an electrode, evaporating the solvent to produce a composite film from which the solvent has been removed, absorbing a liquid electrolyte into the composite film, and covering it with an opposite electrode.

[0152] Example 1

[0153] An organic active material of Chemical Formula 1 was mixed with N-methyl-2-pyrrolidone (NMP) to prepare a mixed slurry. The mixed slurry was applied flatly onto an electrode (anode) using a printing method, doctor blade method, spin coating method, spray coating method, etc., dried, and then the solvent was heat-treated and completely removed to produce a composite film.

[0154] 1M LiPF6 in a 1:1 vol ratio of the liquid electrolyte EC / DMC (ethylene carbonate / dimethyl carbonate) was dripped onto the above solvent-removed composite film to absorb 25% by weight of the liquid electrolyte, and a unit in which the anode and electrolyte were integrated was manufactured. The thickness of the above composite film is 500 nm.

[0155] Subsequently, a secondary battery was manufactured by covering it with a separator and a negative electrode. Here, LiNi was used as the positive electrode. 0.6 Co 0.2 Mn 0.2 A secondary battery was manufactured using O2 and graphite as the cathode.

[0156] Example 2

[0157] A first mixed slurry was prepared by mixing an organic active material of Formula 1 with N-methyl-2-pyrrolidone (NMP), and a second mixed slurry was prepared by mixing an organic active material of Formula 2 with N-methyl-2-pyrrolidone (NMP). The viscosity of the first mixed slurry is 600 cps, and the viscosity of the second mixed slurry is 600 cps (Type B viscometer, 12 rpm, 25 ℃). The first mixed slurry was spread flatly over an electrode, and the second mixed slurry was continuously spread over the spread first mixed slurry and then dried. The solvent was heat-treated and completely removed to produce a first composite film and a second composite film.

[0158] A first composite film containing an organic active material of Formula 1 from which the solvent had been removed and a second composite film containing an organic active material of Formula 2 were dripped with 1M LiPF6 in a 1:1 vol ratio of the liquid electrolyte EC / DMC (ethylene carbonate / dimethyl carbonate), thereby absorbing 25% by weight of the total weight of the composite film, and a unit in which the anode and the multilayer electrolyte were integrated was manufactured. The total thickness of the first composite film and the second composite film is 800 nm.

[0159] Subsequently, a secondary battery was manufactured by covering it with a separator and a negative electrode. Here, LiNi was used as the positive electrode. 0.6 Co 0.2 Mn 0.2 A secondary battery was manufactured using O2 and graphite as the cathode.

[0160] Example 3

[0161] A secondary battery was manufactured using the same method as described in Example 2 above, except that the viscosity of the first mixed slurry was 600 cps and the viscosity of the second mixed slurry was 3000 cps (Type B viscometer, 12 rpm, 25 ℃).

[0162] Example 4

[0163] A secondary battery was manufactured using the same method as described in Example 2 above, except that the viscosity of the first mixed slurry was 2100 cps and the viscosity of the second mixed slurry was 600 cps (Type B viscometer, 12 rpm, 25 ℃).

[0164] Example 5

[0165] An organic active material of Chemical Formula 1 was mixed with N-methyl-2-pyrrolidone (NMP) to prepare a mixed slurry. The mixed slurry was flatly coated onto an electrode using a printing method, doctor blade method, spin coating method, spray coating method, etc., dried, and then the solvent was heat-treated and completely removed to produce a composite film.

[0166] 1M LiPF6 in a 1:1 vol ratio of the liquid electrolyte EC / DMC (ethylene carbonate / dimethyl carbonate) was dripped onto the above solvent-removed composite film to absorb 25% by weight of the liquid electrolyte, and a unit in which the anode and the electrolyte were integrated was manufactured. The thickness of the above composite film is 300 nm.

[0167] A unit in which a cathode and an electrolyte are integrated was manufactured using the same method as the anode described above, and then a secondary battery was manufactured by covering the anode unit with a separator and a cathode unit. Here, LiNi was used as the anode. 0.6 Co 0.2 Mn 0.2 A secondary battery was manufactured using O2 and graphite as the cathode.

[0168] Comparative Example 1

[0169] The organic active material of Chemical Formula 1 was added to N-methyl-2-pyrrolidone (NMP) and stirred. Acetylene black and PTFE (polytetrafluoroethylene) were used as the conductive material and binder, respectively, and mixed. An electrode was prepared using a roll press on the uniformly mixed positive electrode.

[0170] A secondary battery was manufactured by laminating a separator and a cathode onto the anode manufactured above and then applying pressure.

[0171] Comparative Example 2

[0172] A first mixed slurry was prepared by mixing an organic active material of Formula 1 with N-methyl-2-pyrrolidone (NMP), and a second mixed slurry was prepared by mixing an organic active material of Formula 2 with N-methyl-2-pyrrolidone (NMP). The first mixed slurry was spread flatly over an electrode and dried, and then the second mixed slurry was spread over the first mixed slurry and dried. Subsequently, the solvent was heat-treated and completely removed to produce a first composite film and a second composite film.

[0173] In the preparation of a first composite film containing an organic active material of Formula 1 and a second composite film containing an organic active material of Formula 2 from which the above solvent has been removed, a secondary battery was prepared in the same manner as in Example 2, except for a difference in the order of application and drying of the slurry.

[0174] Comparative Example 3

[0175] A secondary battery was manufactured using the same method as described in Example 2 above, except that the viscosity of the first mixed slurry was 600 cps and the viscosity of the second mixed slurry was 6500 cps (Type B viscometer, 12 rpm, 25 ℃).

[0176] Comparative Example 4

[0177] A secondary battery was manufactured using the same method as described in Example 2 above, except that the viscosity of the first mixed slurry was 8000 cps and the viscosity of the second mixed slurry was 600 cps (Type B viscometer, 12 rpm, 25 ℃).

[0178] Experimental Example 1: Battery Evaluation

[0179] (1) Evaluation of the initial discharge capacity and efficiency of the battery

[0180] The device was charged at a rate of 0.1 C until the voltage reached 4.25 V (vs. Li), and then cut off at a rate of 0.05 C while maintaining the voltage at 4.25 V (vs. Li). Subsequently, the device was discharged at a rate of 0.1 C until the voltage reached 3.0 V (vs. Li) during discharge (1st cycle). The initial efficiency was calculated as discharge capacity / charge capacity x 100 (%).

[0181] (2) Evaluation of battery life characteristics

[0182] The device was charged at a rate of 0.33C until the voltage reached 4.25V (vs. Li), and then cut off at a rate of 0.1C while maintaining the voltage at 4.25V (vs. Li). Subsequently, the device was discharged at a rate of 0.33C until the voltage reached 3.0V (vs. Li). The above charge-discharge test was repeated 50 times to measure the capacity retention rate of the discharge capacity.

[0183] Table 1 below shows the results for the 0.1C initial capacity, initial efficiency, and 50-cycle capacity retention rate.

[0184] 0.1C Initial Capacity (mAh) 0.1C Initial Efficiency (%) 0.33C 50-Cycle Capacity Retention Rate (%) Comparative Example 14.589 82.1 Example 15.094 91.3 Example 25.095 92.5

[0185] As shown in Table 1 above, the secondary batteries of Examples 1 and 2 are secondary batteries in which the electrode coated with an organic active material and the electrolyte are integrated, and it was confirmed that they have superior reversible capacity and capacity retention rate compared to the secondary battery of Comparative Example 1 in which the electrode and electrolyte layers are stacked separately.

[0186] In addition, the secondary battery of Example 2, which contains a multilayer mixture of different organic active materials, showed an improved capacity retention rate due to increased adhesion between the electrode and the separator compared to the secondary battery of Example 1, which contains a single organic active material.

[0187] Experimental Example 2: Measurement of Adhesion Strength

[0188] The adhesion strength between the electrode and the separator of the secondary battery in Comparative Example 2 and Example 2 above was measured, and the results are shown in Table 2 below.

[0189] Adhesion strength (gf / cm) Comparative Example 215.2 Example 223.7

[0190] As shown in Table 2 above, it was confirmed that the secondary battery of Example 2, in which the first mixed slurry and the second mixed slurry were applied sequentially during the manufacturing process of the secondary battery and then dried simultaneously, had superior adhesion between the electrode and the separator compared to the secondary battery of Comparative Example 2.

[0191] That is, compared to Comparative Example 2, in which a multilayer composite film is manufactured by applying and drying a first mixed slurry and then applying and drying a second mixed slurry in the manufacturing process of a secondary battery, the manufacturing process of the secondary battery of Example 2 can be simplified, and the adhesion between the electrode and the separator can be improved to achieve excellent battery performance.

[0192] Experimental Example 3: Slurry Viscosity Measurement

[0193] The viscosity of the mixed slurry prepared in the secondary battery manufacturing processes of Examples 2 to 4 and Comparative Examples 3 and 4 was measured, respectively. The results are listed in Table 3 below.

[0194] In addition, to compare the performance of the battery according to the viscosity of the above-mentioned mixed slurry, a charge-discharge test was repeated for 50 cycles, and the capacity retention rate of the discharge capacity was measured. The results are listed in Table 4 below.

[0195] Viscosity (cps) of the first mixed slurry Viscosity (cps) of the second mixed slurry Viscosities of the first mixed slurry and the second mixed slurry Comparative Example 360068001:1 1.3 Comparative Example 480006001 3.3:1 Example 26006001:1 Example 360030001:5 Example 421006003.5:1

[0196] Dose Retention Rate (%) Comparative Example 380.9 Comparative Example 478.7 Example 292.5 Example 392.7 Example 491.9

[0197] As shown in Tables 3 and 4 above, changes in battery performance according to the viscosity ratio of the mixed slurry in the battery manufacturing process were confirmed. It was confirmed that when the viscosity ratio of the first mixed slurry and the second mixed slurry exceeds the range of 1:10 to 10:1, it affects battery performance, and the capacity retention rate of the batteries manufactured in Comparative Examples 3 and 4 is significantly lower compared to Examples 2 to 4.

Claims

1. (a) A step of preparing a mixed slurry comprising an organic active material containing a radical and a solvent; (b) a step of applying the mixed slurry prepared in step (a) to one of the electrodes, then drying and heat-treating to remove the solvent and forming a composite film; (c) a step of manufacturing an electrode unit in which the electrode and the electrolyte are integrated by absorbing a liquid electrolyte into the composite film formed in step (b) above; and (d) a step of stacking an opposite electrode on the electrode unit manufactured in step (c); comprising a method for manufacturing a secondary battery.

2. In Paragraph 1, A method for manufacturing a secondary battery, wherein step (a) comprises the step of preparing a first mixed slurry comprising a first organic active material containing a nitroxyl radical and a solvent; and a second mixed slurry comprising a second organic active material different from the first organic active material and a solvent.

3. In Paragraph 2, The above step (b) comprises the step of applying a first mixed slurry to one of the electrodes, applying a second mixed slurry over the applied first mixed slurry, and then simultaneously drying and heat-treating to remove the solvent and forming a first composite film and a second composite film, a method for manufacturing a secondary battery.

4. In Paragraph 3, The above step (c) comprises the step of manufacturing an electrode unit in which an electrode and a multilayer electrolyte are integrated by absorbing a liquid electrolyte into a first composite film and a second composite film.

5. A first mixed slurry comprising an organic active material containing a radical and a solvent is applied to one of the first electrodes, and then heat-treated and dried to remove the solvent and form a first composite film, and a liquid electrolyte is absorbed into the formed first composite film to manufacture a first electrode unit in which the first electrode and the electrolyte are integrated. At the same time or sequentially, a second mixed slurry different from the first mixed slurry is applied to one of the second electrodes, then heat-treated and dried to remove the solvent and form a second composite film, and a liquid electrolyte is absorbed into the formed second composite film to manufacture a second electrode unit in which the second electrode and the electrolyte are integrated. A method for manufacturing a secondary battery by stacking the first electrode unit and the second electrode unit manufactured above.

6. In Paragraph 1, A method for manufacturing a secondary battery, wherein the organic active material is a compound of any one of the following chemical formulas 1 to 9: [Chemical Formula 1] [Chemical Formula 2] [Chemical Formula 3] [Chemical Formula 4] [Chemical Formula 5] (n is 5 to 1000) [Chemical Formula 6] (n is 5 to 1000) [Chemical Formula 7] (n is 5 to 1000) [Chemical Formula 8] (n is 5 to 1000) [Chemical Formula 9] [Chemical Formula 10] 7. In Paragraph 1, A method for manufacturing a secondary battery, wherein the thickness of the composite film formed in step (b) above is 100 nm to 1000 nm.

8. In Paragraph 2, A method for manufacturing a secondary battery, wherein the viscosity ratio of the first mixed slurry and the second mixed slurry is 1:10 to 10:

1.

9. In Paragraph 1, A method for manufacturing a secondary battery, wherein the content of the liquid electrolyte is 1 to 30 weight% based on the total weight of the composite film.

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