Slurry for positive electrode, manufacturing method of slurry for positive electrode and lithium secondary battery

Abstract

According to one embodiment of the present disclosure, a method for preparing an anode slurry may be provided, comprising: a step of preparing a first mixture comprising an anode active material and an acid additive; a step of preparing a second mixture comprising a conductive material and a dispersant; and a step of mixing the first mixture and the second mixture.

Description

Technology Field

[0001] The present disclosure relates to an anode slurry, a method for manufacturing an anode slurry, and a lithium secondary battery. Background Technology

[0002] As the electronics, telecommunications, and space industries develop, the demand for lithium secondary batteries as an energy source is rapidly increasing. In particular, as the importance of global eco-friendly policies is emphasized, the electric vehicle market is growing exponentially, and active research and development on lithium secondary batteries is being carried out both domestically and internationally.

[0003] A lithium secondary battery comprises a positive electrode, a negative electrode, and a separator disposed between them, and the positive electrode and the negative electrode are each provided with an active material capable of inserting and extracting lithium ions.

[0004] Meanwhile, the anode slurry for manufacturing the anode may include not only active materials but also conductive materials and dispersants. The dispersion state of the conductive material can affect cell resistance and cell lifespan, and accordingly, research to improve the dispersion state of the conductive material is being discussed. The problem to be solved

[0005] Embodiments of the present disclosure provide an anode slurry in which aggregation of the dispersant is prevented and the dispersion state of the conductive material is improved, a method for manufacturing the anode slurry, and a lithium secondary battery. means of solving the problem

[0006] A method for preparing an anode slurry according to an embodiment of the present disclosure may be provided, comprising: a step of preparing a first mixture comprising an anode active material and an acid additive; a step of preparing a second mixture comprising a conductive material and a dispersant; and a step of mixing the first mixture and the second mixture.

[0007] A method for preparing an anode slurry according to an embodiment of the present disclosure comprises: a step of preparing a first mixture comprising an anode active material; a step of preparing a second mixture comprising a conductive material and a dispersant; and a step of mixing the first mixture and the second mixture; wherein the phase angle of the anode slurry is 500 sec under a frequency environment of 1 Hz. -1 A method for manufacturing an anode slurry can be provided, wherein the anode is 3° to 45° when a shear stress with a shear rate of is provided for 300 seconds.

[0008] A lithium secondary battery may be provided, comprising: an anode manufactured using the above anode slurry; and a cathode including a cathode active material layer. Effects of the invention

[0009] According to one embodiment of the present disclosure, an anode slurry in which aggregation of the dispersant is prevented and the dispersion state of the conductive material is improved, a method for manufacturing the anode slurry, and a lithium secondary battery may be provided. Brief explanation of the drawing

[0010] FIG. 1 is a schematic cross-sectional view of a lithium secondary battery according to an embodiment. FIG. 2 is a flowchart schematically illustrating a method for manufacturing an anode slurry according to an example. Figures 3 and 4 are images showing experimental results to verify whether filter passage proceeds normally during a process using an anode slurry according to an example and a comparative example. Specific details for implementing the invention

[0011] Specific structural or functional descriptions of embodiments according to the concept of the present disclosure disclosed in this specification or application are provided merely for the purpose of explaining embodiments according to the concept of the present disclosure, and embodiments according to the concept of the present disclosure may be implemented in various forms and should not be interpreted as being limited to the embodiments described in this specification or application.

[0012] The present disclosure relates to an anode slurry, a method for manufacturing an anode slurry, and a lithium secondary battery.

[0013] Hereinafter, an anode slurry, a method for manufacturing the anode slurry, and a lithium secondary battery according to an embodiment will be described with reference to the attached drawings.

[0015] 1. Lithium secondary battery

[0016] FIG. 1 is a schematic cross-sectional view of a lithium secondary battery according to an embodiment.

[0017] Referring to FIG. 1, the lithium secondary battery (1) may include an outer casing (110), a positive electrode (120), a negative electrode (140), and a separator (160).

[0018] The outer member (110) is provided to surround the internal components of the lithium secondary battery (1) so as to protect the internal components from external influences. The outer member (110) may be of one type among pouch type, can type, and prismatic type, and is not limited to specific examples.

[0019] The positive electrode (120) and the negative electrode (140) may each include a current collector and an active material layer disposed on the current collector. For example, the positive electrode (120) may include a positive current collector and a positive active material layer, and the negative electrode (140) may include a negative current collector and a negative active material layer.

[0020] The current collector may include a known conductive material within a range that does not cause a chemical reaction within the lithium secondary battery (1). For example, the current collector may include any one of stainless steel, nickel (Ni), aluminum (Al), titanium (Ti), copper (Cu), and alloys thereof, and may be provided in various forms such as a film, sheet, or foil.

[0021] The active material layer includes an active material. For example, the positive electrode active material layer may include a positive electrode active material, and the negative electrode active material layer may include a negative electrode active material.

[0022] The positive electrode active material may be a material capable of inserting and extracting lithium (Li) ions. The positive electrode active material may be a lithium metal oxide. For example, the positive electrode active material may be one of a lithium manganese oxide, a lithium nickel oxide, a lithium cobalt oxide, a lithium nickel manganese oxide, a lithium nickel cobalt manganese oxide, a lithium nickel cobalt aluminum oxide, a lithium iron phosphate compound, a lithium manganese phosphate compound, a lithium cobalt phosphate compound, or a lithium vanadium phosphate compound. For example, the positive electrode active material may be LiNi 0.88 Co 0.06 Mn 0.06 O2 and LiNi 0.83 Co 0.085 Mn 0.085 It may include O2. However, the present disclosure is not necessarily limited to the examples described above.

[0023] The negative electrode active material may be a material capable of absorbing and extracting lithium ions. For example, the negative electrode active material may be any one of carbon-based materials such as crystalline carbon, amorphous carbon, carbon composites, and carbon fibers, lithium alloys, silicon (Si), and tin (Sn). According to the embodiments, the negative electrode active material may be natural graphite or artificial graphite, but is not limited to specific examples.

[0024] The positive electrode (120) and the negative electrode (140) may each further include a binder and a conductive material.

[0025] The binder can improve mechanical stability by mediating the bonding between the current collector and the active material layer. According to the examples, the binder may be an organic binder or a water-based binder, and may be used together with a thickener such as carboxymethyl cellulose (CMC). According to the examples, the organic binder is any one of vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene fluoride (PVDF), polyacrylonitrile, and polymethylmethacrylate, and the water-based binder may be styrene-butadiene rubber (SBR), but is not necessarily limited thereto.

[0026] The conductive material can improve the electrical conductivity of the lithium secondary battery (1). The conductive material may include a metal-based material. According to an embodiment, the conductive material may include a conventional carbon-based conductive material. For example, the conductive material may include any one of graphite, carbon black, graphene, and carbon nanotubes. Preferably, the conductive material may include carbon nanotubes.

[0027] A separator (160) may be placed between the anode (120) and the cathode (140). The separator (160) is configured to prevent an electrical short circuit between the anode (120) and the cathode (140) and to allow for the flow of ions.

[0028] According to the embodiment, the separator (160) may include a porous polymer film or a porous nonwoven fabric. Here, the porous polymer film may be composed of a single layer or multiple layers including polyolefin-based polymers such as ethylene polymer, propylene polymer, ethylene / butene copolymer, ethylene / hexene copolymer, and ethylene / methacrylate copolymer. The porous nonwoven fabric may include high melting point glass fibers or polyethylene terephthalate fibers. However, it is not limited thereto, and according to the embodiment, the separator may be a high heat-resistant separator (CCS; Ceramic Coated Separator) including ceramic.

[0029] According to an embodiment, an electrode cell (100) including an anode (120), a cathode (140), and a separator (160) may be provided. A plurality of electrode cells (100) may be provided and sequentially stacked within an outer member (110).

[0030] According to an embodiment, an electrode cell (100) including a positive electrode (120), a negative electrode (140), and a separator (160) may be provided. A plurality of electrode cells (100) may be provided and may be wound, laminated, or folded, thereby providing an electrode assembly (10).

[0031] An electrode assembly (10) is provided together with an electrolyte so that a lithium secondary battery (1) according to an embodiment can be manufactured. According to an embodiment, the lithium secondary battery (1) may be any one of a cylindrical, prismatic, pouch, and coin type using a can, but is not limited thereto.

[0032] The electrolyte may be a non-aqueous electrolyte. The electrolyte may contain a lithium salt and an organic solvent.

[0033] According to the examples, the organic solvent may include one of propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethylmethyl carbonate (EMC), methylpropyl carbonate (MPC), dipropyl carbonate (DPC), vinylene carbonate (VC), dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, sulfolane, gamma-butyrolactone, propylene sulfide, and tetrahydrofuran.

[0035] 2. Method for manufacturing anode slurry

[0036] Hereinafter, with reference to FIG. 2, a method for manufacturing an anode slurry for manufacturing an anode (120) according to an embodiment will be described. Any content that may overlap with the above description will be briefly explained or omitted.

[0037] FIG. 2 is a flowchart schematically illustrating a method for manufacturing an anode slurry according to an example.

[0038] Referring to FIG. 2, a method for manufacturing an anode slurry may include the step of manufacturing a first mixture (S120), the step of manufacturing a second mixture (S140), and the step of mixing the first mixture and the second mixture (S160).

[0039] The step of preparing the first mixture (S120) and the step of preparing the second mixture (S140) can be performed separately.

[0040] The order of the step of preparing the first mixture (S120) and the step of preparing the second mixture (S140) is not limited to specific examples. For instance, the step of preparing the first mixture (S120) may be performed prior to the step of preparing the second mixture (S140), and the step of preparing the second mixture (S140) may be performed prior to the step of preparing the first mixture (S120). According to an embodiment, the step of preparing the first mixture (S120) and the step of preparing the second mixture (S140) may be performed within the same time interval, while each step (S120, S140) may be performed separately.

[0041] In the step of preparing the first mixture (S120), the first mixture may be provided. Here, the first mixture may include an anode active material, a binder, a first solvent, and an acid additive. The first mixture may refer to a mixture of the anode active material, the binder, the first solvent, and the acid additive.

[0042] In this step, the positive active material, binder, first solvent, and acid additive may be mixed.

[0043] An acid additive is an acidic substance and may refer to a substance added to the first mixture. For example, the acid additive may include maleic acid.

[0044] According to the example, the acid additive can prevent gelation that may occur in the first mixture.

[0045] When a large number of hydroxide ions are present in a mixture for experimentally preparing an anode slurry, a material can be provided in which the hydroxide ions and the binder react to form a polymer. For example, when the binder is polyvinylidene fluoride (PVDF), a defluorination reaction between the hydroxide ions and the polyvinylidene fluoride (PVDF) may occur. Accordingly, double bonds between carbons may be formed, and depending on the embodiment, a free radical polymerization reaction may occur, resulting in a gelation phenomenon.

[0046] However, according to the embodiment, an acid additive is included in the first mixture, so that the gelation phenomenon can be reduced. For example, the acid ions of the acid additive can react with hydroxide ions that may be present in the first mixture, and the hydroxide ions in the first mixture can be removed. Accordingly, as described above, the gelation phenomenon that may occur due to the presence of hydroxide ions can be prevented.

[0047] In addition, according to the example, the first mixture may contain an acid additive, so that the increase in viscosity due to atmospheric moisture may be suppressed.

[0048] The first solvent may include a substance suitable for mixing the substances of the first mixture. For example, water or an organic solvent may be used as the first solvent. The first solvent may include one of NMP (N-methylpyrrolidone), DMF (dimethylformamide), acetone, and dimethylacetamide. However, the present disclosure is not necessarily limited to the examples described above.

[0049] According to the example, the viscosity of the first mixture may be 10 Pa·s or higher. According to the example, the viscosity of the first mixture may be 100 Pa·s or higher.

[0050] According to the embodiment, the phase angle of the first mixture may be 45° to 90° when no separate shear stress is applied. In this case, the phase angle of the first mixture may be measured in an environment where the frequency is 1 Hz. For example, when the first mixture includes PVDF as a binder, NMP as a first solvent, and maleic acid as an acid additive, the phase angle of the first mixture may be 50° to 70° when no separate shear stress is applied.

[0051] In the step of preparing the second mixture (S140), the second mixture may be provided. Here, the second mixture may include a conductive material, a dispersant, and a second solvent. The second mixture may refer to a mixture of the conductive material, the dispersant, and the second solvent.

[0052] In this step, the conductive material, the dispersant, and the second solvent may be mixed.

[0053] The second solvent may include a substance suitable for mixing the materials of the second mixture. For example, NMP (n-Methyl Pyrrolidone) may be used as the second solvent. However, the present disclosure is not necessarily limited to the examples described above.

[0054] The dispersant may be selected from the group consisting of alkanes, aryls, polyvinyl pyridine, polyacrylates, glycols, PVdF (polyvinylidene fluoride), polyurethanes, ketones, carbonates, benzenes, and mixtures thereof.

[0055] According to the examples, the dispersant may be any one selected from PAA (poly acrylic acid), PVP (poly vinyl pyrrolidone), and NMP (n-methyl pyrrolidone), or a mixture thereof. Preferably, the dispersant may include H-NBR (nitrile butadiene rubber).

[0056] In the step (S160) of mixing the first mixture and the second mixture, the first mixture and the second mixture may be mixed, and accordingly, an anode slurry according to the embodiment may be prepared.

[0057] According to the example, the solid content of the manufactured anode slurry may be 70% to 80%.

[0058] According to the example, the phase angle of the anode slurry is 500 sec under a frequency environment of 1 Hz. -1 When a shear stress with a shear rate is applied for 300 seconds, it can be 10° to 45°.

[0059] For example, when carbon nanotubes are included as a conductive material for the anode slurry and the first mixture includes an acid additive, the phase angle of the anode slurry may be 5° to 45° under the above measurement conditions. When carbon nanotubes are included as a conductive material for the anode slurry and the first mixture includes an acid additive, the phase angle of the anode slurry may be 10° to 30° under the above measurement conditions.

[0060] As another example, when carbon black is included as a conductive material of the anode slurry and H-NBR is included as a dispersant, and the first mixture includes an acid additive, the phase angle of the anode slurry under the above measurement conditions may be 35° to 45°.

[0061] Meanwhile, according to the embodiment, a step of transferring process materials between individual steps may be performed. For example, after the step of mixing the first mixture and the second mixture (S160), the anode slurry may be transferred through a specific path. Additionally, the first mixture prepared in the step of preparing the first mixture (S120) may be transferred through a specific path. Additionally, the second mixture prepared in the step of preparing the second mixture (S140) may be transferred through a specific path.

[0062] At this time, in order to prevent impurities from being included in the anode slurry, a step of filtering impurities in the transfer path may be performed. For example, the anode slurry may pass through a filter member to filter out impurities. The first mixture may pass through a filter member to filter out impurities. The second mixture may pass through a filter member to filter out impurities.

[0063] According to the embodiments, the filter member may have a mesh shape. However, the shape of the filter member is not necessarily limited to the examples described above.

[0064] According to the embodiments, even when the step of filtering the impurities is performed, filter clogging may not occur, and accordingly, processability may be improved. Detailed information regarding this will be described later with reference to experimental examples.

[0065] According to the embodiment, the acid additive included in the first mixture is provided separately from the conductive material and dispersant included in the second mixture, so that the dispersion state of the conductive material can be improved.

[0066] Experimentally, acid additives form bonds with the dispersant, which can expose a portion of the conductive material and cause it to aggregate with adjacent conductive materials. In other words, acid additives can weaken the interaction between the conductive material and the dispersant, and in this case, the dispersibility of the conductive material may be reduced.

[0067] However, according to the embodiments, a first mixture containing an acid additive and a second mixture containing a conductive material and a dispersant can be prepared separately, and accordingly, the reaction between the acid additive and the dispersant can be minimized. Consequently, according to the embodiments, the dispersibility of the conductive material can be improved.

[0068] Furthermore, if the dispersibility of the conductive material is improved, the resistance of the anode manufactured using the manufactured anode slurry can be reduced, and accordingly, the cell life can be improved.

[0069] The anode (120) according to the embodiment can be manufactured by coating, drying, and pressing the manufactured anode slurry onto a current collector.

[0071] Hereinafter, examples and comparative examples are described so that those skilled in the art to which this disclosure pertains can easily implement them. However, the embodiments of this disclosure may be implemented in forms different from those described below and are not necessarily limited to specific embodiments.

[0073] (1) Examples and Comparative Examples

[0074] [Example 1]

[0075] To prepare the anode slurry according to Example 1, a first mixture and a second mixture were prepared separately.

[0076] To prepare the first mixture, an NCM-based cathode active material, PVDF, NMP, and maleic acid were mixed. LiNi was used as the cathode active material. 0.88 Co 0.06 Mn 0.06 O2 and LiNi 0.83 Co 0.085 Mn 0.085 A material mixed with O2 was used. Here, LiNi 0.88 Co 0.06 Mn 0.06 O2, LiNi 0.83 Co 0.085 Mn 0.085O2, a 10 wt% PVDF solution, NMP, and maleic acid were prepared in amounts of 30.000 g, 12.857 g, 5.244 g, 5.311 g, and 0.06 g, respectively, and mixed at a mixing speed of 1000 rpm for 2 minutes. Meanwhile, the maleic acid content was LiNi 0.88 Co 0.06 Mn 0.06 It was provided with an O2 content of 0.2%, and the solid content of the first mixture was prepared at 81.2%.

[0077] To prepare a second mixture, carbon nanotubes, H-NBR, and NMP were mixed in amounts of 0.2622 g, 0.05243 g, and 4.929 g, respectively. Accordingly, a second mixture was prepared having a solid content of 6% (e.g., containing 6% by weight of carbon nanotubes and H-NBR).

[0078] Subsequently, the first mixture and the second mixture were mixed at a mixing speed of 1000 rpm for 10 minutes to prepare the anode slurry according to Example 1.

[0080] [Example 2]

[0081] As in Example 1, the first mixture and the second mixture were prepared separately.

[0082] Example 2 differs from Example 1 in that carbon black is used as a conductive material.

[0083] To prepare the first mixture, an NCM-based cathode active material, PVDF, NMP, and maleic acid were mixed. LiNi was used as the cathode active material. 0.88 Co 0.06 Mn 0.06 O2 and LiNi 0.83 Co 0.085 Mn 0.085 A material mixed with O2 was used. Here, LiNi 0.88 Co 0.06 Mn 0.06 O2, LiNi 0.83 Co 0.085 Mn 0.085O2, a 10 wt% PVDF solution, NMP, and maleic acid were prepared in amounts of 30.000 g, 12.857 g, 5.368 g, 0.058 g, and 0.06 g, respectively, and mixed at a mixing speed of 1000 rpm for 2 minutes. Meanwhile, the content of maleic acid was LiNi 0.88 Co 0.06 Mn 0.06 It was provided with an O2 content of 0.2%, and the solid content of the first mixture was prepared at 89.9%.

[0084] To prepare a second mixture, carbon black, H-NBR, and NMP were mixed in amounts of 1.341 g, 0.083 g, and 10.452 g, respectively. Accordingly, a second mixture was prepared having a solid content of 12% (e.g., containing 12% by weight of carbon black and H-NBR).

[0085] Subsequently, the first mixture and the second mixture were mixed at a mixing speed of 1000 rpm for 10 minutes to prepare an anode slurry according to Example 2.

[0087] [Example 3]

[0088] As in Example 1, the first mixture and the second mixture were prepared separately.

[0089] Example 3 differs from Example 1 in that carbon black is used as a conductive material and H-NBR is not included in the second mixture.

[0090] To prepare the first mixture, an NCM-based cathode active material, PVDF, NMP, and maleic acid were mixed. LiNi was used as the cathode active material. 0.88 Co 0.06 Mn 0.06 O2 and LiNi 0.83 Co 0.085 Mn 0.085 A material mixed with O2 was used. Here, LiNi 0.88 Co 0.06 Mn 0.06 O2, LiNi 0.83 Co 0.085 Mn 0.085O2, a 10 wt% PVDF solution, NMP, and maleic acid were prepared in amounts of 30.000 g, 12.857 g, 5.368 g, 2.237 g, and 0.06 g, respectively, and mixed at a mixing speed of 1000 rpm for 2 minutes. Meanwhile, the content of maleic acid was LiNi 0.88 Co 0.06 Mn 0.06 It was provided with an O2 content of 0.2%, and the solid content of the first mixture was prepared at 86.0%.

[0091] To prepare a second mixture, 1.342 g of carbon black and 8.244 g of NMP were mixed. Accordingly, a second mixture was prepared having a solid content of 14% (e.g., containing 14% by weight of carbon black).

[0092] Subsequently, the first mixture and the second mixture were mixed at a mixing speed of 1000 rpm for 10 minutes to prepare the anode slurry according to Example 3.

[0094] [Example 4]

[0095] As in Example 1, the first mixture and the second mixture were prepared separately.

[0096] Example 4 differs from Example 1 in that the first mixture does not contain an acid additive.

[0097] To prepare the first mixture, an NCM-based cathode active material, PVDF, and NMP were mixed. LiNi was used as the cathode active material. 0.88 Co 0.06 Mn 0.06 O2 and LiNi 0.83 Co 0.085 Mn 0.085 A material mixed with O2 was used. Here, LiNi 0.88 Co 0.06 Mn 0.06 O2, LiNi 0.83 Co 0.085 Mn 0.08530.000 g of O2, 12.857 g of a 10 wt% PVDF solution, and 5.244 g of NMP were prepared, respectively, and mixed for 2 minutes at a mixing speed of 1000 rpm. The solid content of the first mixture was prepared to be 81.2%.

[0098] To prepare a second mixture, carbon nanotubes, H-NBR, and NMP were mixed in amounts of 0.2622 g, 0.05243 g, and 4.929 g, respectively. Accordingly, a second mixture was prepared having a solid content of 6% (e.g., containing 6% by weight of carbon nanotubes and H-NBR).

[0099] Subsequently, the first mixture and the second mixture were mixed at a mixing speed of 1000 rpm for 10 minutes to prepare the anode slurry according to Example 4.

[0101] [Example 5]

[0102] As in Example 1, the first mixture and the second mixture were prepared separately.

[0103] Example 5 differs from Example 1 in that carbon black is used as a conductive material, H-NBR is not included in the second mixture, and acid additives are not included in the first mixture.

[0104] To prepare the first mixture, an NCM-based cathode active material, PVDF, and NMP were mixed. LiNi was used as the cathode active material. 0.88 Co 0.06 Mn 0.06 O2 and LiNi 0.83 Co 0.085 Mn 0.085 A material mixed with O2 was used. Here, LiNi 0.88 Co 0.06 Mn 0.06 O2, LiNi 0.83 Co 0.085 Mn 0.08530.000 g of O2, 12.857 g of a 10 wt% PVDF solution, and 2.237 g of NMP were prepared, and mixed at a mixing speed of 1000 rpm for 2 minutes. The solid content of the first mixture was prepared to be 86.0%.

[0105] To prepare a second mixture, 1.342 g of carbon black and 8.244 g of NMP were mixed. Accordingly, a second mixture was prepared having a solid content of 14% (e.g., containing 14% by weight of carbon black).

[0106] Subsequently, the first mixture and the second mixture were mixed at a mixing speed of 1000 rpm for 10 minutes to prepare the anode slurry according to Example 5.

[0108] [Comparative Example]

[0109] The first mixture was not prepared separately, but was mixed with the second mixture in a single batch.

[0110] To prepare an anode slurry according to a comparative example, an NCM-based anode active material, PVDF, NMP, maleic acid, and a second mixture were mixed.

[0111] To prepare a second mixture, carbon nanotubes, H-NBR, and NMP were mixed in amounts of 0.2622 g, 0.05243 g, and 4.929 g, respectively. Accordingly, a second mixture was prepared having a solid content of 6% (e.g., containing 6% by weight of carbon nanotubes and H-NBR).

[0112] As the positive electrode active material, LiNi is used in the same way as in Example 1. 0.88 Co 0.06 Mn 0.06 O2 and LiNi 0.83 Co 0.085 Mn 0.085 A material mixed with O2 was used. Here, LiNi 0.88 Co 0.06 Mn 0.06 O2, LiNi 0.83 Co 0.085 Mn0.085 O2, PVDF solution, NMP, maleic acid, and the second mixture were prepared in amounts of 30.000g, 12.857g, 5.244g, 5.311g, 0.06g, and 5.244g, respectively, and mixed at a mixing speed of 1000 rpm for 10 minutes. Accordingly, an anode slurry according to the comparative example was prepared.

[0114] (2) Rheological properties

[0115] The rheological properties between the examples and comparative examples were compared. Specifically, the solid content, viscosity, and phase angle of the first mixture, second mixture, and cathode active material prepared according to the examples and comparative examples were measured and are shown in Table 1.

[0116] In this case, the solid content in Table 1 represents the solid content of the prepared first mixture, second mixture, and anode slurry. Also, the viscosity in Table 1 is 1 sec -1 This represents the viscosity of the subject measured at the shear rate. The phase angle in Table 1 was measured in an environment with a frequency of 1 Hz before the application of shear stress, and also in an environment with a frequency of 1 Hz after the application of shear stress. Here, the shear rate of the shear stress is 500 sec⁻¹ -1 It was controlled for 300 seconds.

[0117] division Solids[%] Viscosity [Pa·s] Phase angle Shear stress transfer After shear stress Example 1 First mixture 81.2 17.2 69.1 56.5 2nd mixture 6.0 3.3 33.2 45.8 slurry 74.5 34.6 18.9 20.1 Example 2 First mixture 90.0 202.1 1.02 2.11 2nd mixture 14.0 98.3 4.7 6.9 slurry 74.5 132.5 58.2 39.1 Example 3 First mixture 86.0 191.5 52.1 33.9 2nd mixture 14.0 104.7 1.36 2.31 slurry 74.5 156.4 9.1 10.9 Example 4 First mixture 81.2 16.8 76.2 52.6 2nd mixture 6.0 3.3 33.2 45.8 slurry 74.5 2.5 75.4 66.2 Example 5 First mixture 86.0 116.8 67.3 24.6 2nd mixture 14.0 104.7 1.36 2.31 slurry 74.5 4.1 50.3 60.5 Comparative example slurry 74.5 39.8 18.8 17.6

[0118] Referring to Example 1, Example 3, and Comparative Example in Table 1 above, when an acid additive is further included in the first mixture, the phase angle of the manufactured anode slurry can be provided to be 45° or less. In this case, during the step of filtering impurities, the anode slurry may not pass through the filter member normally. However, according to the example, even though the acid additive is included in the first mixture, the first mixture and the second mixture are prepared separately, so that filter clogging issues that may occur during the transfer of the anode slurry, the first mixture, and the second mixture can be reduced.

[0119] In addition, referring to Examples 2 and 3 of Table 1 above, when H-NBR is further included in the second mixture, the phase angle of the slurry can be prepared relatively high, which means that when the second mixture further includes H-NBR, the dispersibility of the conductive material is further improved.

[0121] (3) Slurry processability test

[0122] The processability of the anode slurry between the examples and comparative examples was compared. Specifically, to proceed with the process, filter clogging was checked when transporting the anode slurries prepared according to the examples and comparative examples. Filter clogging was determined by passing the anode slurry through a filter to check whether excessive impurities were generated and, consequently, whether the slurry flowability was good. Accordingly, the filter clogging status for filtering impurities when transporting the prepared anode slurries is shown in Table 2.

[0123] Figures 3 and 4 are images showing experimental results to verify whether filter passage proceeds normally during a process using an anode slurry according to the examples and comparative examples. The experiment was conducted by passing the manufactured anode slurry through a filter containing a mesh structure and analyzing the results. The filter used was manufactured with a 120 mesh specification and is made of stainless steel. Here, the 120 mesh specification refers to a mesh structure containing mesh holes formed by dividing the width and length into 120 equal parts when the width and length are each 1 inch.

[0124] FIG. 3 is an image showing normal filter passage while transporting an anode slurry according to an embodiment. FIG. 4 is an image showing filter clogging that occurs while transporting an anode slurry according to a comparative example. For example, FIG. 3 relates to Example 1 and is an image showing an impurity filter in which filter clogging does not occur, and FIG. 4 relates to a comparative example and is an image showing an impurity filter in which filter clogging occurs.

[0125] division Whether the filter is clogged Example 1 X Example 2 X Example 3 X Example 4 X Example 5 X Comparative example O

[0126] Referring to Table 2, Figure 3, and Figure 4, it can be seen that the anode slurry according to the embodiment does not experience filter clogging during the transfer process, whereas the anode slurry according to the comparative example experiences filter clogging during the transfer process. Accordingly, according to the embodiment, an anode slurry with improved processability can be provided. Explanation of the symbols

[0127] 1: Lithium secondary battery 10: Electrode assembly 100: Electrode cell 110: Exterior component 120: Anode 140: Cathode 160: Separator

Claims

Claim 1 A method for preparing an anode slurry, comprising: a step of preparing a first mixture comprising an anode active material and an acid additive; a step of preparing a second mixture comprising a conductive material and a dispersant; and a step of mixing the first mixture and the second mixture. Claim 2 A method for manufacturing an anode slurry according to claim 1, wherein the phase angle of the first mixture is 45° to 90° when no shear stress is applied. Claim 3 In claim 1, the phase angle of the anode slurry is 500 sec under a frequency environment of 1 Hz. -1 A method for preparing an anode slurry having a shear rate of 10° to 45° when a shear stress with a shear rate is applied for 300 seconds. Claim 4 A method for manufacturing an anode slurry according to claim 1, wherein the conductive material comprises carbon nanotubes. Claim 5 In claim 4, the phase angle of the anode slurry is 500 sec under a frequency environment of 1 Hz. -1 A method for preparing an anode slurry having a shear rate of 10° to 30° when a shear stress with a shear rate is applied for 300 seconds. Claim 6 A method for manufacturing an anode slurry according to claim 1, wherein the dispersant comprises H-NBR. Claim 7 A method for manufacturing an anode slurry according to claim 1, wherein the conductive material comprises carbon black. Claim 8 In claim 7, the dispersant comprises H-NBR, and the phase angle of the anode slurry is 500 sec -1 A method for preparing an anode slurry having a shear rate of 35° to 45° when a shear stress with a shear rate is applied for 300 seconds. Claim 9 A method for manufacturing an anode slurry according to claim 1, further comprising the step of transferring the anode slurry; wherein the step of transferring the anode slurry comprises the step of passing the anode slurry through a filter member. Claim 10 A method for manufacturing an anode slurry according to claim 1, wherein the solid content of the anode slurry is 70% to 80%. Claim 11 A method for preparing an anode slurry according to claim 1, wherein the anode active material comprises one of a lithium manganese-based oxide, a lithium nickel-based oxide, a lithium cobalt-based oxide, a lithium nickel manganese-based oxide, a lithium nickel cobalt manganese-based oxide, a lithium nickel cobalt aluminum-based oxide, a lithium iron phosphate-based compound, a lithium manganese phosphate-based compound, a lithium cobalt phosphate-based compound, or a lithium vanadium phosphate-based compound. Claim 12 A method for preparing an anode slurry according to claim 1, wherein the acid additive comprises maleic acid. Claim 13 A method for preparing an anode slurry according to claim 1, wherein the first mixture further comprises a binder, and the binder is polyvinylidene fluoride. Claim 14 delete Claim 15 delete Claim 16 delete Claim 17 Anode slurry prepared according to the method for preparing an anode slurry according to claim 1. Claim 18 A lithium secondary battery comprising: an anode manufactured using an anode slurry according to claim 17; and a cathode comprising a cathode active material layer.

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