Manufacturing method of high-energy-density lithium battery capacitor

Abstract

The invention discloses a manufacturing method of a high-energy-density lithium battery capacitor. The lithium battery capacitor is formed by compounding a nickel-cobalt-manganese ternary positive electrode material, activated carbon, a binder, a conductive agent, hard carbon, graphite, an aluminum foil coated with a conductive layer and a copper foil coated with a conductive layer, the positive electrode is prepared by uniformly stirring and mixing a nickel-cobalt-manganese ternary material, activated carbon, a binder, a conductive agent and a solvent, stirring at a high speed and then using a coating machine; and the negative electrode is prepared by uniformly stirring and mixing hard carbon, graphite, a binder, a conductive agent and a solvent, stirring at a high speed and then using a coating machine. According to the manufacturing method of the lithium battery capacitor, the high-performance hybrid capacitor with high power density and high energy density can be obtained, and the lithium battery capacitor can be widely applied to the fields of light rail vehicle power sources, power generation and energy storage, electric / hybrid electric vehicles, energy storage type trackless electric vehicle power sources and the like and has huge potential and wide market.

Description

Technical Field

[0001] The invention belongs to the field of battery-capacitor hybrid devices, and in particular relates to a method for manufacturing a high-energy-density lithium battery capacitor. Background Art

[0002] Lithium battery capacitor is a new energy storage system that combines the high energy density of lithium-ion batteries with the high power density of capacitors, excellent cycle life and excellent fast charging performance. It includes a capacitor electrode, a lithium-ion battery electrode, an organic lithium salt electrolyte and a diaphragm. Lithium battery capacitor combines the high specific capacity of lithium-ion batteries and the wide voltage window of organic electrolytes to improve its energy density, while its fast charging performance is achieved by the role of capacitor electrodes. At present, there are two configurations of lithium battery capacitors. One uses lithium ion battery positive electrode materials as positive electrodes and activated carbon or mesoporous carbon as negative electrodes; the other uses lithium ion battery negative electrode materials as negative electrodes and activated carbon or mesoporous carbon as positive electrodes. For example, the invention patent (CN100383902C) introduces a hybrid supercapacitor, in which a mesoporous carbon positive electrode is combined with a compound negative electrode doped with a single or multiple metal element. However, lithium battery capacitors still have a relatively low energy density. Summary of the invention

[0003] The present invention discloses a method of increasing the mass proportion of positive electrode active material in the electrode by changing different ratios and optimizing the preparation process, thereby improving the energy density of lithium battery capacitance and improving the performance of lithium ion hybrid capacitor. According to one embodiment, the high energy density lithium battery capacitor includes: a current collector, a positive electrode active material, a negative electrode active material, a separator, an electrolyte, one or more conductive agents, one or more binders, and a conductive coating. Preferably, the positive electrode of the current collector is a graphene-coated aluminum foil and the negative electrode is a carbon-coated copper foil. Preferably, the positive electrode material active material is composed of NCM811 and activated carbon in a mass ratio of 5:1, with a mass percentage of 80% to 92%. Preferably, the conductive agent is a composite of one or more one-dimensional conductive agents of graphene, carbon nanotubes, and carbon fibers and one or more zero-dimensional conductive agents of SP conductive agents, acetylene black, and conductive graphite, with a mass percentage of 2% to 7%. Preferably, the separator is preferably a PP separator with a thickness of 25 microns. Preferably, the electrolyte is preferably 1.0M LiPF6 in EC:DEC=1:1 Vol% with 5.0%FEC. Preferably, the binder is one or a mixture of polyvinylidene fluoride, polytetrafluoroethylene, polyacrylonitrile, polymethyl methacrylate, sodium carboxymethyl cellulose, styrene-butadiene rubber, polyvinyl alcohol, polyvinyl pyrrolidone, sodium polyacrylate, polyethylene oxide, with a mass percentage of 2% to 7%. DETAILED DESCRIPTION

[0004] Exemplary embodiments are described in detail below. However, these embodiments are exemplary and the present disclosure is not limited thereto. According to one embodiment, a high energy density lithium battery capacitor includes: a current collector, a positive electrode active material, a negative electrode active material, a separator, an electrolyte, one or more conductive agents, one or more binders, and a conductive coating.

[0005] Example 1: Preparation of positive electrode sheet: Mix 200g of NCM, activated carbon, conductive carbon black, and PVDF in a mass ratio of 75:15:5:5, adjust to slurry with NMP, and then apply it on 15μm graphene-coated aluminum foil, and the thickness of the material area on one side is 100 microns. Preparation of negative electrode sheet: Mix 200g of hard carbon, graphite, conductive carbon black, and CMC in a mass ratio of 45:45:5:5, adjust to slurry with pure water, and then apply it on 10μm carbon-coated copper foil, and the thickness of the material area on one side is 110 microns. After drying (110-120℃), rolling, cutting (positive electrode size is 10*10 cm2, negative electrode size is 10.3*10.3 cm2), vacuum drying (120℃) for 48h, it is made into a pole sheet. PP was selected as the separator, and the positive electrode sheets (15 sheets), separators, and negative electrode sheets (16 sheets) were stacked into a battery cell. Then, the positive electrode groups of the stacked battery cells were spot welded on the aluminum tabs, and the negative electrode groups were welded on the nickel tabs. The welded battery cells were placed in the formed aluminum-plastic film, and 40 mL of electrolyte was injected after the top seal, and the mouth was sealed to assemble into a square lithium battery capacitor. The initial internal resistance was 2.5mΩ. After 0.1C activation, the capacity of the battery capacitor was 5.5Ah, and the energy density was 110Wh / Kg. After 10,000 cycles of 5C charge and discharge, the capacity retention rate was above 90%.

[0006] Example 2: Preparation of positive electrode sheet: Mix 200g of NCM, activated carbon, conductive carbon black, and PVDF in a mass ratio of 80:10:5:5, adjust to slurry with NMP, and then apply it on 15μm graphene-coated aluminum foil, and the thickness of the material area on one side is 100 microns. Preparation of negative electrode sheet: Mix 200g of hard carbon, graphite, conductive carbon black, and CMC in a mass ratio of 45:45:5:5, adjust to slurry with pure water, and then apply it on 10μm carbon-coated copper foil, and the thickness of the material area on one side is 110 microns. After drying (110-120℃), rolling, cutting (positive electrode size is 10*10 cm2, negative electrode size is 10.3*10.3 cm2), vacuum drying (120℃) for 48h, it is made into a pole sheet. PP was selected as the separator, and the positive electrode sheets (15 sheets), separators, and negative electrode sheets (16 sheets) were stacked into a battery cell. Then, the positive electrode groups of the stacked battery cells were spot welded on the aluminum tabs, and the negative electrode groups were welded on the nickel tabs. The welded battery cells were placed in the formed aluminum-plastic film, and 40 mL of electrolyte was injected after the top seal, and the mouth was sealed to assemble into a square lithium battery capacitor. The initial internal resistance was 2.5mΩ. After 0.1C activation, the capacity of the battery capacitor was 5.4Ah, and the energy density was 108Wh / Kg. After 10,000 cycles of 5C charge and discharge, the capacity retention rate was above 90%.

[0007] Example 3: Preparation of positive electrode sheet: Mix 200g of NCM, activated carbon, conductive carbon black, and PVDF in a mass ratio of 75:15:5:5, adjust to slurry with NMP, and then apply it on 15μm graphene-coated aluminum foil, and the thickness of the material area on one side is 100 microns. Preparation of negative electrode sheet: Mix 200g of hard carbon, graphite, conductive carbon black, and CMC in a mass ratio of 50:40:5:5, adjust to slurry with pure water, and then apply it on 10μm carbon-coated copper foil, and the thickness of the material area on one side is 110 microns. After drying (110-120℃), rolling, cutting (positive electrode size is 10*10 cm2, negative electrode size is 10.3*10.3 cm2), vacuum drying (120℃) for 48h, it is made into a pole sheet. PP was selected as the separator, and the positive electrode sheets (15 sheets), separators, and negative electrode sheets (16 sheets) were stacked into a battery cell. Then, the positive electrode groups of the stacked battery cells were spot welded on the aluminum tabs, and the negative electrode groups were welded on the nickel tabs. The welded battery cells were placed in the formed aluminum-plastic film, and 40 mL of electrolyte was injected after the top seal, and the mouth was sealed to assemble into a square lithium battery capacitor. The initial internal resistance was 2.5mΩ. After 0.1C activation, the capacity of the battery capacitor was 5.5Ah, and the energy density was 110Wh / Kg. After 10,000 cycles of 5C charge and discharge, the capacity retention rate was above 90%.

[0008] Example 4: Preparation of positive electrode sheet: Mix 200g of NCM, activated carbon, conductive carbon black, and PVDF in a mass ratio of 70:20:5:5, adjust to slurry with NMP, and then apply it on 15μm graphene-coated aluminum foil, and the thickness of the material area on one side is 100 microns. Preparation of negative electrode sheet: Mix 200g of hard carbon, graphite, conductive carbon black, and CMC in a mass ratio of 45:45:5:5, adjust to slurry with pure water, and then apply it on 10μm carbon-coated copper foil, and the thickness of the material area on one side is 110 microns. After drying (110-120℃), rolling, cutting (positive electrode size is 10*10 cm2, negative electrode size is 10.3*10.3 cm2), vacuum drying (120℃) for 48h, it is made into a pole sheet. PP was selected as the separator, and the positive electrode sheets (15 sheets), separators, and negative electrode sheets (16 sheets) were stacked into a battery cell. Then, the positive electrode groups of the stacked battery cells were spot welded on the aluminum tabs, and the negative electrode groups were welded on the nickel tabs. The welded battery cells were placed in the formed aluminum-plastic film, and 40 mL of electrolyte was injected after the top seal, and the mouth was sealed to assemble into a square lithium battery capacitor. The initial internal resistance was 2.5mΩ. After 0.1C activation, the capacity of the battery capacitor was 5.0Ah, and the energy density was 100Wh / Kg. After 10,000 cycles of 5C charge and discharge, the capacity retention rate was above 90%.

[0009] Example 5: Preparation of positive electrode sheet: Mix 200g of NCM, activated carbon, conductive carbon black, and PVDF in a mass ratio of 60:30:5:5, adjust to slurry with NMP, and then apply it on 15μm graphene-coated aluminum foil, and the thickness of the material area on one side is 100 microns. Preparation of negative electrode sheet: Mix 200g of hard carbon, graphite, conductive carbon black, and CMC in a mass ratio of 45:45:5:5, adjust to slurry with pure water, and then apply it on 10μm carbon-coated copper foil, and the thickness of the material area on one side is 110 microns. After drying (110-120℃), rolling, cutting (positive electrode size is 10*10 cm2, negative electrode size is 10.3*10.3 cm2), vacuum drying (120℃) for 48h, it is made into a pole sheet. PP was selected as the separator, and the positive electrode sheets (15 sheets), separators, and negative electrode sheets (16 sheets) were stacked into a battery cell. Then, the positive electrode groups of the stacked battery cells were spot welded on the aluminum tabs, and the negative electrode groups were welded on the nickel tabs. The welded battery cells were placed in the formed aluminum-plastic film, and 40 mL of electrolyte was injected after the top seal, and the mouth was sealed to assemble into a square lithium battery capacitor. The initial internal resistance was 2.5mΩ. After 0.1C activation, the capacity of the battery capacitor was 4.5Ah, and the energy density was 90Wh / Kg. After 10,000 cycles of 5C charge and discharge, the capacity retention rate was above 90%.

[0010] Example 6: Preparation of positive electrode sheet: Mix 200g of NCM, activated carbon, conductive carbon black, and PVDF in a mass ratio of 50:40:5:5, adjust to slurry with NMP, and then apply it on 15μm graphene-coated aluminum foil, and the thickness of the material area on one side is 100 microns. Preparation of negative electrode sheet: Mix 200g of hard carbon, graphite, conductive carbon black, and CMC in a mass ratio of 45:45:5:5, adjust to slurry with pure water, and then apply it on 10μm carbon-coated copper foil, and the thickness of the material area on one side is 110 microns. After drying (110-120℃), rolling, cutting (positive electrode size is 10*10 cm2, negative electrode size is 10.3*10.3 cm2), vacuum drying (120℃) for 48h, it is made into a pole sheet. PP was selected as the separator, and the positive electrode sheets (15 sheets), separators, and negative electrode sheets (16 sheets) were stacked into a battery cell. Then, the positive electrode groups of the stacked battery cells were spot welded on the aluminum tabs, and the negative electrode groups were welded on the nickel tabs. The welded battery cells were placed in the formed aluminum-plastic film, and 40 mL of electrolyte was injected after the top seal, and the mouth was sealed to assemble into a square lithium battery capacitor. The initial internal resistance was 2.5mΩ. After 0.1C activation, the capacity of the battery capacitor was 4.0Ah, and the energy density was 80Wh / Kg. After 10,000 cycles of 5C charge and discharge, the capacity retention rate was above 90%.

[0011] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to perform equivalent replacements on parts thereof. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention. Although the above describes the specific implementation methods of the present invention, it is not intended to limit the protection scope of the present invention. Those skilled in the art should understand that, based on the technical solution of the present invention, various modifications or deformations that can be made by those skilled in the art without creative labor are still within the protection scope of the present invention.

Claims

1. A high energy density lithium battery capacitor, characterized in that: The lithium battery capacitor is composited by nickel-cobalt-manganese ternary positive electrode materials in different proportions, activated carbon, a binder, a conductive agent, hard carbon, graphite, and aluminum foil and copper foil coated with a conductive layer.

2. The lithium battery capacitor according to claim 1, characterized in that: The positive electrode is made of nickel-cobalt-manganese ternary material, activated carbon, a binder, a conductive agent and a solvent, which are uniformly mixed and stirred at a high speed and then prepared by a coating machine.

3. The lithium battery capacitor according to claim 1, characterized in that: The negative electrode is prepared by using a coating machine after hard carbon, graphite, a binder, a conductive agent and a solvent are uniformly mixed and stirred at a high speed.

4. The lithium battery capacitor according to claim 1, characterized in that: The binder comprises one or a mixture of sodium carboxymethyl cellulose, polyvinyl pyrrolidone, polyvinylidene fluoride, sodium polyacrylate, polytetrafluoroethylene, styrene-butadiene rubber, polymethyl methacrylate, polyvinyl alcohol, polyacrylonitrile and polyethylene oxide.

5. The lithium battery capacitor according to claim 1, characterized in that: The cathode solvent is N-methylpyrrolidone.

6. The lithium battery capacitor according to claim 1, characterized in that: The negative electrode solvent is water.

7. The lithium battery capacitor according to claim 1, characterized in that: The positive electrode active material has a thickness of 50-180 μm and a density of 1.8-3.7 g / cm 3 .

8. The lithium battery capacitor according to claim 1, characterized in that: The thickness of the negative electrode active material is 30-200 μm and the density is 0.8-1.2 g / cm 3 .

9. A method for preparing a lithium battery capacitor according to any one of claims 1 to 7, characterized in that: The preparation steps are as follows: stacking the dried negative electrode, separator, and positive electrode into the form of n negative electrodes + n-1 positive electrodes by the stacking method, and then performing programmed operations such as spot welding, top sealing, liquid injection, and packaging to prepare a lithium-ion battery capacitor of a specific thickness.