Manufacturing method of lithium ion capacitor

Abstract

To provide a manufacturing method of a lithium ion capacitor for solving a problem that a manufacturing cost of the lithium ion capacitor is high.SOLUTION: A manufacturing method of a lithium ion capacitor, contains: a positive electrode manufacturing step of manufacturing a positive electrode sheet by mixing a high-lithium material, an active carbon, a conductive assistant, and an aqueous adhesive agent to obtain a slurry by adding water as a solvent, and thereafter manufacturing a positive electrode sheet by coating them to a carbon coating aluminum foil; a negative electrode manufacturing step of mixing a negative electrode material, the conductive assistant, and the aqueous adhesive agent to form the slurry by adding water as a solvent, and thereafter, manufacturing a negative electrode sheet by coating them to a copper foil; and an assembling step of assembling the positive electrode sheet, the negative electrode sheet, an electrolyte, and a separator to which lithiation is not made to the capacitor.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a method for producing a lithium ion capacitor, and in particular to a method for producing a lithium ion capacitor using water as a solvent. [Background technology]

[0002] Lithium-ion capacitors are capacitors with high energy density and high safety. The positive electrode uses an electrode compound based on activated carbon, just like supercapacitors, and the negative electrode uses negative electrode materials commonly used in general batteries, such as graphite, soft carbon, and hard carbon, so they simultaneously possess the rapid charge and discharge characteristics of supercapacitors and the high energy density characteristics of lithium batteries.

[0003] When manufacturing a lithium-ion capacitor using the negative electrode of a conventional battery, a pre-lithiation process using lithium metal is required, which requires expensive equipment and a strictly controlled environment, and also requires the use of organic solvents in the process to make the electrode, which keeps the cost of the lithium-ion capacitor high.

[0004] Therefore, in order to reduce the manufacturing costs of lithium ion capacitors, the industry is looking for lithium ion capacitors that can reduce material costs and production environmental requirements. Summary of the Invention [Problem to be solved by the invention]

[0005] Therefore, an object of the present invention is to provide a method for manufacturing a lithium ion capacitor so as to solve the problem of high manufacturing costs of the lithium ion capacitor. [Means for solving the problem]

[0006] In order to solve the problems of the prior art, the present invention provides a method for manufacturing a lithium ion capacitor, comprising: a positive electrode manufacturing step of mixing a high-lithium material, activated carbon, a conductive assistant, and an aqueous adhesive, adding water as a solvent to prepare a slurry, and applying the slurry to a carbon-coated aluminum foil to manufacture a positive electrode sheet; a negative electrode manufacturing step of mixing a negative electrode material, a conductive assistant, and an aqueous adhesive, adding water as a solvent to prepare a slurry, and applying the slurry to a copper foil to manufacture a negative electrode sheet; and an assembly step of assembling the positive electrode sheet, which has not been prelithiated, the negative electrode sheet, an electrolyte, and a separator into a capacitor.

[0007] In one embodiment of the present invention, there is provided a method for producing a lithium ion capacitor, wherein the high-lithium material is lithium manganate or lithium oxalate.

[0008] In one embodiment of the present invention, there is provided a method for producing a lithium ion capacitor, wherein the activated carbon is activated carbon for supercapacitors, porous carbon, or high surface area carbon black.

[0009] In one embodiment of the present invention, there is provided a method for producing a lithium ion capacitor, wherein the conductive assistant is conductive carbon black or general carbon black.

[0010] In one embodiment of the present invention, there is provided a method for producing a lithium ion capacitor, wherein the negative electrode material is graphite, soft carbon or hard carbon.

[0011] In one embodiment of the present invention, there is provided a method for producing a lithium ion capacitor, characterized in that an electrolyte for a lithium battery is used as the electrolyte.

[0012] In one embodiment of the present invention, there is provided a method for producing a lithium ion capacitor, characterized in that a plastic diaphragm, a cellulose diaphragm, or a glass fiber diaphragm is used as a separator.

[0013] In one embodiment of the present invention, there is provided a method for producing a lithium ion capacitor, further comprising an activation step of activating the capacitor at a charging rate of 0.1 to 0.5 mV / sec and a voltage of 2.2 to 3.8 V. Effect of the Invention

[0014] According to the technical means of the present invention, a high-lithium material such as lithium manganese oxide (LMO) is mixed as a lithium source into the positive electrode material, and a coating slurry is produced using water as a solvent. In addition, a coating slurry is also produced using water as a solvent in the production of the negative electrode. This reduces the processing costs involved in assembling the negative electrode sheet and the positive electrode sheet into a lithium ion capacitor after a pre-lithiation process in which the negative electrode sheet of a conventional lithium ion capacitor further reacts with lithium metal. In addition, since this method can be applied to current battery manufacturing technology, there is no need to develop new equipment, and the manufacturing costs of lithium ion capacitors can be further reduced. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following describes embodiments of the present invention, which are merely illustrative of the embodiments of the present invention and are not intended to limit the present invention.

[0016] According to the method for producing a lithium ion capacitor of the present invention, an electrode sheet is produced using water as a solvent, and a 1000 m 2 A high surface area carbon material of 0.1g or more is mixed with a small amount of LMO material as a lithium source, and then mixed with a conductive additive, a water-based adhesive, and water to make a slurry, which is then applied to a carbon-coated aluminum foil to produce a positive electrode sheet.

[0017] Alternatively, a negative electrode material such as artificial graphite, soft carbon or hard carbon is mixed with a conductive assistant, and then mixed with an aqueous adhesive, similarly using water as a solvent, to prepare a slurry, which is then applied to copper foil to produce a negative electrode sheet.

[0018] The manufactured positive electrode sheet, negative electrode sheet, separator and electrolyte are assembled into a lithium ion capacitor, which is then subjected to an activation process and then tested.

[0019] Example 1 According to one embodiment of the method for manufacturing a lithium ion capacitor of the present invention, activated carbon, conductive carbon black and high lithium LMO are premixed in a ratio of 5:1:1 to obtain an active material, and then an aqueous adhesive with a solid content of 5 wt% equal to the weight of the active material is added, and water is further added as a solvent. Activated carbon: conductive carbon black: LMO: adhesive: water is 5:1:1:7:14. The slurry is then continuously ground using a ball mill at 300 rpm for 3 hours, and applied to a carbon-coated aluminum foil with a thickness of 16 μm using a 200 μm scraper, and the moisture is removed using an oven at 110 ° C to obtain a positive electrode sheet.

[0020] Next, the soft carbon and conductive carbon black are premixed in a ratio of 10:1 to obtain the active material, and then an aqueous adhesive with a solid content of 5 wt% equal to the weight of the active material is added, and water is further added as a solvent. The ratio of soft carbon:conductive carbon black:adhesive:water is 10:1:11:32. The slurry is then continuously ground using a ball mill at 300 rpm for 3 hours, and applied to a copper foil with a thickness of 8 μm using a 50 μm scraper, and the moisture is removed using an oven at 110 °C to obtain a negative electrode sheet.

[0021] Next, assemble the button capacitor using 1M LiPF6 / (EC / DEC) as the electrolyte and a plastic diaphragm as the separator in the following order: top cover, positive electrode sheet, separator, negative electrode sheet, spring plate, and bottom cover.

[0022] Example 2 According to one embodiment of the method for manufacturing a lithium ion capacitor of the present invention, activated carbon, conductive carbon black and high lithium LMO are premixed in a ratio of 5:1:1 to obtain an active material, and then an aqueous adhesive with a solid content of 5 wt% equal to the weight of the active material is added, and water is further added as a solvent. Activated carbon: conductive carbon black: LMO: adhesive: water is 5:1:1:7:14. The slurry is then continuously ground using a ball mill at 300 rpm for 3 hours, and applied to a carbon-coated aluminum foil with a thickness of 16 μm using a 200 μm scraper, and the moisture is removed using an oven at 110 ° C to obtain a positive electrode sheet.

[0023] Next, the soft carbon and conductive carbon black are premixed in a ratio of 10:1 to obtain the active material, and then an aqueous adhesive with a solid content of 5 wt% equal to the weight of the active material is added, and water is further added as a solvent. The ratio of soft carbon:conductive carbon black:adhesive:water is 10:1:11:32. The slurry is then continuously ground using a ball mill at 300 rpm for 3 hours, and applied to a copper foil with a thickness of 8 μm using a 50 μm scraper, and the moisture is removed using an oven at 110 °C to obtain a negative electrode sheet.

[0024] Next, a button capacitor is assembled using 1M LiPF6 / (EC / DEC) as the electrolyte and a cellulose diaphragm as the separator in the following order: top cover, positive electrode sheet, separator, negative electrode sheet, spring plate, and bottom cover.

[0025] Example 3 According to one embodiment of the method for manufacturing a lithium ion capacitor of the present invention, activated carbon, conductive carbon black and high lithium LMO are premixed in a ratio of 5:1:1 to obtain an active material, and then an aqueous adhesive with a solid content of 5 wt% equal to the weight of the active material is added, and water is further added as a solvent. Activated carbon: conductive carbon black: LMO: adhesive: water is 5:1:1:7:14. The slurry is then continuously ground using a ball mill at 300 rpm for 3 hours, and applied to a carbon-coated aluminum foil with a thickness of 16 μm using a 200 μm scraper, and the moisture is removed using an oven at 110 ° C to obtain a positive electrode sheet.

[0026] Next, the soft carbon and conductive carbon black are premixed in a ratio of 10:1 to obtain the active material, and then an aqueous adhesive with a solid content of 5 wt% equal to the weight of the active material is added, and water is further added as a solvent. The ratio of soft carbon:conductive carbon black:adhesive:water is 10:1:11:32. The slurry is then continuously ground using a ball mill at 300 rpm for 3 hours, and applied to a copper foil with a thickness of 8 μm using a 50 μm scraper, and the moisture is removed using an oven at 110 °C to obtain a negative electrode sheet.

[0027] Next, a button capacitor is assembled using 1M LiPF6 / (EC / DEC) as the electrolyte and a glass fiber diaphragm as the separator in the following order: top cover, positive electrode sheet, separator, negative electrode sheet, spring plate, and bottom cover.

[0028] Comparative Example 1 Activated carbon and conductive carbon black are premixed in a ratio of 5:1 to obtain the active material, and then an aqueous adhesive with a solid content of 5 wt% equal to the weight of the active material is added, followed by the addition of water as a solvent: activated carbon: conductive carbon black: adhesive: water = 5:1:1:20. The slurry is then continuously ground using a ball mill at 300 rpm for 3 hours, and applied to a carbon-coated aluminum foil with a thickness of 16 μm using a 200 μm scraper, and the moisture is removed using an oven at 110 °C to obtain a positive electrode sheet.

[0029] Next, the soft carbon and conductive carbon black are premixed in a ratio of 10:1 to obtain the active material, and then an aqueous adhesive with a solid content of 5 wt% equal to the weight of the active material is added, and water is further added as a solvent. The ratio of soft carbon:conductive carbon black:adhesive:water is 10:1:11:32. The slurry is then continuously ground using a ball mill at 300 rpm for 3 hours, and applied to a copper foil with a thickness of 8 μm using a 50 μm scraper, and the moisture is removed using an oven at 110 °C to obtain a negative electrode sheet.

[0030] Next, assemble the button capacitor using 1M LiPF6 / (EC / DEC) as the electrolyte and a plastic diaphragm as the separator in the following order: top cover, positive electrode sheet, separator, negative electrode sheet, spring plate, and bottom cover.

[0031] The button capacitors manufactured in Examples 1 to 3 and Comparative Example 1 were activated for 5 cycles at a current density of 0.01 A / g and 2.2 to 3.8 V, and then the weight specific capacitance was measured in the operating voltage range of 2.2 to 3.8 V, the energy density of the capacitor was measured, and the energy density after 50,000 cycles of charging and discharging at a current density of 0.5 was measured, and the results are shown in Table 1. In addition, in Comparative Example 1, the range of energy density loss after charging and discharging is too large, so only the energy density value after 1,000 cycles of charging and discharging is shown.

[0032] [Table 1]

[0033] As can be seen from Table 1, the capacitor of Comparative Example 1, which does not contain high-lithium material, has a weight-specific capacitance of 135.27 F / g in the operating voltage range of 2.2 to 3.8 V, and an energy density of the entire capacitor of 46.55 Wh / kg. After 1000 charge / discharge cycles at a current density of 0.5 A / g, it can only maintain 3.23 Wh / kg.

[0034] In contrast, the capacitor of Example 1 has a weight-specific capacitance of 166.84 F / g in the operating voltage range of 2.2 to 3.8 V, an energy density of the entire capacitor of 58.40 Wh / kg, and can maintain 39.16 Wh / kg after 50,000 charge / discharge cycles at a current density of 0.5 A / g.

[0035] The capacitor of Example 2 has a weight-specific capacitance of 170.06 F / g in the operating voltage range of 2.2 to 3.8 V, and an energy density of 59.74 Wh / kg for the entire capacitor, which can be maintained at 44.69 Wh / kg after 50,000 charge / discharge cycles at a current density of 0.5 A / g.

[0036] The capacitor of Example 3 has a weight-specific capacitance of 175.35 F / g in the operating voltage range of 2.2 to 3.8 V, and an energy density of 62.18 Wh / kg for the entire capacitor, which can be maintained at 31.74 Wh / kg after 50,000 charge / discharge cycles at a current density of 0.5 A / g.

[0037] As can be seen from the results, the capacitors of Examples 1 to 3 have high capacitance and a low rate of loss of energy density after multiple cycles of discharge, ie, a long life.

[0038] According to the technical means of the present invention, a high-lithium material such as lithium manganese oxide (LMO) is mixed as a lithium source into the positive electrode material, and a coating slurry is prepared using water as a solvent. In addition, a coating slurry is also prepared for the negative electrode material using water as a solvent. This reduces the processing costs involved in assembling the positive electrode sheet and lithium ion capacitor after a pre-lithiation process in which the negative electrode sheet of a conventional lithium ion capacitor is further reacted with lithium metal, and can be applied to current battery manufacturing technology, without the need to develop new equipment, and reduces the manufacturing costs of lithium ion capacitors.

[0039] Although the preferred embodiments of the present invention have been disclosed as above, they are by no means intended to limit the present invention. Various changes and modifications can be made within the scope of the present invention. Therefore, the claims of the present invention should be broadly interpreted to include such changes and modifications.

Claims

1. A positive electrode manufacturing step of mixing high-lithium material, activated carbon, conductive assistant, and water-based adhesive, adding water as a solvent to prepare a slurry, and then applying the slurry to a carbon-coated aluminum foil to manufacture a positive electrode sheet; a negative electrode manufacturing step of mixing the negative electrode material, the conductive assistant, and the water-based adhesive, adding water as a solvent to make a slurry, and then applying it to a copper foil to manufacture a negative electrode sheet; and an assembly step of assembling the positive electrode sheet that has not been pre-lithiated, the negative electrode sheet, an electrolyte, and a separator into a capacitor.

2. 2. The method for producing a lithium ion capacitor according to claim 1, wherein the high-lithium material is lithium manganate or lithium oxalate.

3. 2. The method for producing a lithium ion capacitor according to claim 1, wherein the activated carbon is activated carbon for supercapacitors, porous carbon, or high surface area carbon black.

4. 2. The method for manufacturing a lithium ion capacitor according to claim 1, wherein the conductive assistant is conductive carbon black or general carbon black.

5. 2. The method for producing a lithium ion capacitor according to claim 1, wherein the negative electrode material is graphite, soft carbon or hard carbon.

6. 2. The method for producing a lithium ion capacitor according to claim 1, wherein an electrolyte for a lithium battery is used as the electrolyte.

7. 2. The method for producing a lithium ion capacitor according to claim 1, wherein a plastic diaphragm, a cellulose diaphragm or a glass fiber diaphragm is used as the separator.

8. The method for producing a lithium ion capacitor according to claim 1, further comprising an activation step of activating the capacitor at a charging rate of 0.1 to 0.5 mV / s and a voltage of 2.2 to 3.8 V.

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