Electrode manufacturing method

Abstract

To provide a manufacturing method of an electrode, in which a drying time of an electrode paste can be reduced.SOLUTION: A manufacturing method of an electrode comprises steps of: coating a collector 3 with an electrode paste 5; and drying the applied electrode paste 5. The step of drying contains steps of: radiating the electrode paste 5 with laser while blowing a hot wind to the electrode paste 5; and measuring a temperature of the hot wind. In the step of radiating the laser, the laser is adjusted on the basis of temperature information of the hot wind measured in the step of measuring so that a total sum of a heat output per unit area applied to the electrode paste 5 from the hot wind and a heat output per unit area applied to the electrode paste from the laser becomes a heat output per unit area required for drying the electrode paste.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing an electrode. [Background technology]

[0002] Conventionally, as a method for manufacturing electrodes, Japanese Patent Application Laid-Open No. 2023-531013 (Patent Document 1) discloses a technology in which a current collector coated with a slurry (electrode paste) is dried using hot air and medium-wave infrared rays, and then the current collector is further dried using a laser heat source. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-531013 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when drying the slurry by blowing hot air onto the current collector, it takes a considerable amount of time for the temperature of the hot air blown from the hot air irradiator to rise sufficiently, which raises concerns that it may take a long time to dry the slurry.

[0005] The present disclosure has been made in consideration of the above-mentioned problems, and an object of the present disclosure is to provide a method for manufacturing an electrode that can shorten the drying time of an electrode paste. [Means for solving the problem]

[0006] An electrode manufacturing method according to the present disclosure includes the steps of applying an electrode paste to a current collector and drying the applied electrode paste. The drying step includes the steps of irradiating the electrode paste with a laser while blowing hot air onto the electrode paste and measuring the temperature of the hot air. In the laser irradiation step, the laser is adjusted based on information about the temperature of the hot air measured in the measuring step so that the sum of the heat output per unit area imparted to the electrode paste from the hot air and the heat output per unit area imparted to the electrode paste from the laser is the heat output per unit area required to dry the electrode paste.

[0007] According to the above configuration, even if it takes time for the air temperature to reach a predetermined temperature and air lower than the predetermined temperature is blown onto the electrode paste, a sufficient amount of heat can be applied to the electrode paste by adjusting the heat output per unit area applied to the electrode paste from the laser side, thereby shortening the drying time of the electrode paste even when the temperature of the blown air is low. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to provide a method for manufacturing an electrode that can shorten the drying time of an electrode paste. [Brief explanation of the drawings]

[0009] [Figure 1] 5A to 5C are schematic diagrams for explaining a method for manufacturing an electrode according to an embodiment. [Figure 2] FIG. 2 is a flow chart showing a manufacturing process of an electrode according to an embodiment. [Figure 3] FIG. 10 is a diagram showing the relationship between the temperature of hot air and the heat output per unit applied to the electrode paste from the laser in the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the embodiments described below, the same or common parts are denoted by the same reference numerals in the drawings, and the description thereof will not be repeated.

[0011] Fig. 1 is a schematic diagram for explaining a method for manufacturing an electrode according to an embodiment. Fig. 2 is a flow chart showing the manufacturing steps of an electrode according to an embodiment. The method for manufacturing an electrode according to an embodiment will be explained with reference to Figs. 1 and 2.

[0012] The electrode according to the embodiment is formed by drying electrode paste 5 applied to current collector 3 by coating device 10 using laser irradiation device 20 and hot air irradiation device 30.

[0013] The current collector 3 is conveyed in the conveying direction (direction AR1) by the conveying rollers 2. A known current collector for lithium ion secondary batteries can be used as the current collector 3. The current collector 3 is a chemically inactive electrical conductor that allows current to continue to flow through the positive electrode active material layer and the negative electrode active material layer during discharging or charging of the lithium ion secondary battery. The material of the current collector 3 is, for example, a metal material, a conductive resin material, or a conductive inorganic material.

[0014] The coating device 10 applies the electrode paste 5 to the main surface of the current collector 3. As the coating device 10, for example, a die coater or the like can be adopted.

[0015] The electrode paste 5 contains an active material and a solvent (dispersion medium). The configuration of the electrode paste may be the same as that of an electrode paste used in a known electrode manufacturing method that includes coating and drying the electrode paste.

[0016] When the electrode paste 5 is a positive electrode paste for a lithium ion secondary battery, the positive electrode paste contains a positive electrode active material and a solvent. Examples of the positive electrode active material include lithium composite metal oxides having a layered rock salt structure, metal oxides having a spinel structure, and polyanionic compounds. The positive electrode active material may be any material that can be used in lithium ion secondary batteries.

[0017] The positive electrode paste may further contain a conductive material, a binder, etc. Examples of the conductive material include carbon black such as acetylene black (AB) and other carbon materials (such as graphite). Examples of the binder include polyvinylidene fluoride (PVDF).

[0018] When the electrode paste 5 is a negative electrode paste for a lithium-ion secondary battery, the negative electrode paste contains a negative electrode active material and a solvent. Examples of the negative electrode active material include Li, carbon, and metal compounds. The negative electrode active material may be an element or a compound thereof that can be alloyed with lithium. Examples of carbon include graphite, hard carbon, and soft carbon. Examples of the solvent include water.

[0019] The negative electrode paste may further contain a binder, a thickener, etc. Examples of binders include styrene butadiene rubber (SBR), etc. Examples of thickeners include carboxymethyl cellulose (CMC), etc.

[0020] The paste refers to a dispersion in which at least a portion of the solid content is dispersed, and includes slurries, inks, and the like.

[0021] The laser irradiation device 20 includes a laser heat source and irradiates the electrode paste 5 with a laser in a surface-emitting manner. The laser irradiation device 20 is configured to be able to adjust the heat output per unit area applied to the electrode paste 5. The heat output of the laser irradiation device 20 is adjusted by a control unit 50. The control unit 50 may be provided inside the laser irradiation device 20 or outside the laser irradiation device 20.

[0022] The hot air irradiation device 30 includes a heater that heats the air and a blower that blows the air. The heater heats the air in the furnace, and the blower blows the heated air (hot air) toward the electrode paste 5 through an air blowing path.

[0023] It takes a certain amount of time for the hot air to reach a predetermined temperature. For this reason, a temperature sensor 40 is provided to measure the temperature of the hot air. A thermocouple, for example, can be used as the temperature sensor 40. The temperature sensor 40 is installed in a position where it does not interfere with the current collector 3 being transported or the electrode paste 5 coated on the current collector 3.

[0024] The method for manufacturing an electrode includes a step (S10) of applying electrode paste 5 onto current collector 3, and a step (S10) of drying the applied electrode paste 5.

[0025] When manufacturing an electrode, first, in step (S10), electrode paste 5 is applied onto current collector 3 using coating device 10. Electrode paste 5 is applied onto main surface 3a of current collector 3, for example.

[0026] Subsequently, in step (S20), the electrode paste 5 coated on the current collector 3 is dried. Specifically, first, in step (S21), a laser is irradiated onto the coated electrode paste 5 while hot air is blown onto the electrode paste 5. The hot air is blown from the hot air irradiation device 30, and the laser is irradiated from the laser irradiation device 20. The electrode paste 5 is dried while moving in the transport direction as the current collector 3 is transported.

[0027] Subsequently, in step (S22), the temperature of the hot air is measured. Specifically, the temperature of the hot air from the hot air irradiation device 30 is measured using the temperature sensor 40. Information about the measured hot air temperature is input to the control unit 50.

[0028] Based on the temperature information, in step (S21), the control unit 50 adjusts the laser so that the sum of the heat output per unit area imparted to the electrode paste 5 from the hot air and the heat output per unit area imparted to the electrode paste 5 from the laser is the heat output per unit area required to dry the electrode paste 5.

[0029] The total heat output A1 (W / cm ) per unit area required to dry the electrode paste 5 2 ), the heat output per unit area A2 (W / cm2) to be applied from the laser 2 ) is calculated as follows:

[0030] The total heat output A1 is calculated by dividing the drying energy (required drying energy) required to dry the electrode paste 5, which is calculated from the solvent basis weight, by the drying time, as shown in the following (Equation 1) to (Equation 3).

[0031] Solvent weight (mg / cm 2 )={basis weight (mg / cm 2 )×(100-NV(wt%))} / NV(wt%)...(Formula 1) Required drying energy (J / cm 2 ) = Solvent basis weight (mg / cm 2 )×N...(Formula 2) Total heat output per unit area required for drying A1 (W / cm 2 ) = Required drying energy (J / cm 2 ) / Drying time (s)...(Equation 3) In the above formula (1), NV indicates the mass percent concentration of solids contained in a substance or mixture. For example, if the solid content of a liquid is 50 wt%, it means that 50% of the liquid's weight is solid components, and the remaining 50% is solvent or water. In the above formula (2), N is an empirical number, for example, 3.2.

[0032] Subsequently, the thermal output per unit area A2 (W / cm2) from the laser to be adjusted 2 ) can be calculated using the following (Equation 4).

[0033] The heat output A2 (W / cm2) per unit area to be applied from the laser to the electrode paste 5 2 ) = Total heat output per unit area required for drying A1 (W / cm 2 ) - Heat output per unit area A3 (W / cm 2 ) given to the electrode paste 5 from the hot air 2)...(Formula 4) Here, the heat output A3 per unit area imparted from the hot air to the electrode paste 5 can be calculated from a predetermined relational expression based on the drying time, air blowing speed, and hot air temperature T (°C). The drying time (s) and air blowing speed (m / s) can be set arbitrarily.

[0034] FIG. 3 is a diagram showing the relationship between the temperature of hot air and the heat output per unit applied to the electrode paste from the laser according to the embodiment.

[0035] As shown in FIG. 3, at predetermined values of the drying time and air blowing speed used in the manufacturing, the temperature of the hot air (°C) and the heat output A2 (W / cm2) per unit area to be applied from the laser to the electrode paste 5 are 2 ) is previously determined by experiments, etc. Thus, the thermal output A2 is determined by measuring the temperature of the hot air, and the control unit 50 adjusts the laser so that the thermal output A2 is obtained.

[0036] As described above, by adjusting the laser based on the temperature of the hot air, it takes time for the temperature of the hot air to reach a predetermined temperature, and even if hot air lower than the predetermined temperature is blown onto the electrode paste 5, a sufficient amount of heat can be imparted to the electrode paste 5. This makes it possible to shorten the drying time of the electrode paste even when the temperature of the hot air is low. In particular, the drying time of the electrode paste can be effectively shortened when the temperature of the hot air is being increased.

[0037] By carrying out the step of drying the electrode paste 5, an active material layer is formed on the current collector 3, and an electrode can be obtained. For the purpose of adjusting the thickness, density, etc. of the active material layer, a step of pressing the active material layer may be carried out after the step of drying the electrode paste. The pressing may be carried out according to a known method. Furthermore, a step of cutting the electrode to a predetermined size may be carried out.

[0038] The above-described electrode manufacturing method can be applied to the manufacture of bipolar electrodes and monopolar electrodes.

[0039] The electrode obtained by the manufacturing method according to this embodiment can be suitably used as an electrode for a secondary battery such as a lithium ion secondary battery according to a known method. Therefore, the manufacturing method of the electrode according to this embodiment is suitably a manufacturing method of an electrode for a secondary battery (particularly a lithium ion secondary battery).

[0040] Secondary batteries, particularly lithium-ion secondary batteries, produced using electrodes obtained by the manufacturing method according to this embodiment can be used in a variety of applications. Suitable applications include power sources for driving vehicles such as electric vehicles (EVs), hybrid vehicles (HVs), and plug-in hybrid vehicles (PHVs); and storage batteries for small-scale power storage devices.

[0041] The embodiments disclosed herein are illustrative in all respects and are not restrictive. The scope of the present invention is defined by the claims, and includes all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0042] 2 conveying roller, 3 current collector, 3a main surface, 5 electrode paste, 10 coating device, 20 laser irradiation device, 30 hot air irradiation device, 40 temperature sensor, 50 control unit.

Claims

[Claim 1] a step of applying the electrode paste onto a current collector; and drying the applied electrode paste. The drying step includes: irradiating the electrode paste with a laser while blowing hot air onto the electrode paste; measuring the temperature of the hot air; In the step of irradiating the laser, the laser is adjusted based on the temperature information of the hot air measured in the step of measuring so that the sum of the heat output per unit area imparted to the electrode paste from the hot air and the heat output per unit area imparted to the electrode paste from the laser is the heat output per unit area required to dry the electrode paste.

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