CN112310393A - Activated carbon electrode, electrochemical device using the same, and electronic apparatus - Google Patents

Activated carbon electrode, electrochemical device using the same, and electronic apparatus Download PDF

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Publication number
CN112310393A
CN112310393A CN202011202806.0A CN202011202806A CN112310393A CN 112310393 A CN112310393 A CN 112310393A CN 202011202806 A CN202011202806 A CN 202011202806A CN 112310393 A CN112310393 A CN 112310393A
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lithium
lithium salt
activated carbon
carbon electrode
battery
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朱意
靳玲玲
申红光
何江龙
李艳
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Zhuhai Cosmx Power Battery Co Ltd
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Zhuhai Cosmx Power Battery Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/665—Composites
    • H01M4/667—Composites in the form of layers, e.g. coatings
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M16/00—Structural combinations of different types of electrochemical generators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Composite Materials (AREA)
  • Materials Engineering (AREA)
  • Inorganic Chemistry (AREA)
  • Battery Electrode And Active Subsutance (AREA)
  • Secondary Cells (AREA)

Abstract

The invention provides an activated carbon electrode, which is doped with lithium by mixing inorganic lithium salt and organic salt, can simultaneously play the advantages of high gram capacity of the inorganic lithium salt and no residue of the organic lithium salt, and provides enough active lithium ions for a negative electrode corresponding to the activated carbon electrode during formation of a film so as to form a stable SEI film. When the activated carbon electrode is used for a hybrid lithium ion storage battery/capacitor battery, the first effect, the cycle performance and the storage performance of the battery can be improved, and the service life of the hybrid lithium ion storage battery/capacitor battery can be prolonged.

Description

Activated carbon electrode, electrochemical device using the same, and electronic apparatus
Technical Field
The invention relates to the technical field of batteries, in particular to an activated carbon electrode, an electrochemical device adopting the activated carbon electrode and electronic equipment.
Background
Hybrid lithium ion battery/capacitor cells are becoming more and more popular for everyday use because they can provide satisfactory power performance and low temperature performance. The hybrid lithium ion storage battery/capacitor battery is composed of at least one pair of graphite negative electrodes and an activated carbon electrode, wherein a compact and stable solid electrolyte interface film (SEI film) needs to be formed on the negative electrode corresponding to the activated carbon electrode during formation so as to be beneficial to maintaining the performances of the hybrid lithium ion storage battery/capacitor battery in the aspects of circulation, storage and the like, but the activated carbon electrode has limited capability of providing lithium ions, so that the generation of the SEI film on the negative electrode corresponding to the activated carbon electrode is not facilitated, and the cycle performance of the battery is reduced due to the fact that the first charge and discharge efficiency of the hybrid lithium ion storage battery/capacitor battery is too low, so that the lithium supplement on the activated carbon electrode is one of ideal methods for ensuring the negative electrode corresponding to the activated carbon electrode to form a stable SEI film and improving the first effect of the battery.
One of the reported lithium replenishing techniques is to adsorb lithium powder on a negative electrode plate through electrostatic interaction to replenish lithium. Although the method has high lithium supplementing efficiency, the production conditions of the method are harsh, special lithium supplementing devices or equipment are required, and the production cost is high. In addition, in the process of spraying lithium powder to the negative pole piece, part of the lithium powder floats in the ambient air, so that great potential safety hazards are caused to production line staff; the other method is to dope inorganic lithium salt into the active carbon electrode, although the method has low cost, high efficiency and controllable pre-lithium intercalation process, and can solve the problems of uncontrollable lithium doping amount and potential safety hazard existing in the method, the product after the lithium removal of the inorganic lithium salt can be retained in the active carbon, so that the hole is blocked and the impedance is increased, and further the related electrical property of the battery is influenced.
Disclosure of Invention
The invention provides an activated carbon electrode which can improve the low-temperature performance, the first effect, the cycle performance and the storage performance of an electrochemical device when being applied to the electrochemical device.
The present invention provides an electrochemical device having high low-temperature performance, first-effect, cycle performance and storage performance.
The present invention provides an electronic apparatus whose driving source and/or energy storage source have high low-temperature performance, first-effect, cycle performance, and storage performance.
The invention provides an activated carbon electrode, which comprises a current collector and a carbon active layer attached to at least one functional surface of the current collector, wherein the carbon active layer comprises 70-95% of activated carbon, 1-30% of lithium salt and 0-10% of functional additive in percentage by mass;
the lithium salt includes organic lithium salt and inorganic lithium salt.
In the above-described activated carbon electrode, the inorganic lithium salt is optionally selected from Li5FeO4、LiAlO2、Li3AsO4、Li3BO3、Li2CO3、Li2GeO3、Li3PO4、Li2SO4、Li2SeO4、Li2SiO3And Li2TeO3At least one of (1).
In the above-described activated carbon electrode, the organic lithium salt may be at least one selected from the group consisting of azide-based lithium salts, oxycarbide-based lithium salts, dicarboxylic acid-based lithium salts, and hydrazide-based lithium salts.
In the above-described activated carbon electrode, the organic lithium salt may be at least one selected from the group consisting of 2-cyclopropene-1-one-2, 3-dihydroxylithium, 3-cyclobutene-1, 2-dione-3, 4-dihydroxylithium, 4-cyclopentene-1, 2, 3-trione-4, 5-dihydroxylithium, 5-cyclohexene-1, 2,3, 4-tetraone-5, 6-dihydroxylithium, lithium oxalate, lithium ketopropionate, lithium diketosuccinate, and lithium trione glutarate.
In the activated carbon electrode, the activated carbon layer optionally includes 5% to 7% by mass of lithium salt.
In the activated carbon electrode, optionally, the lithium salt contains 20 to 70 mass% of an inorganic lithium salt.
In the activated carbon electrode, optionally, the lithium salt contains 50 to 70 mass% of an inorganic lithium salt.
A second aspect of the present invention provides an electrochemical device comprising the above-described activated carbon electrode.
In the above electrochemical device, optionally, the above electrochemical device is a hybrid lithium ion secondary/capacitor cell.
A third aspect of the present invention provides an electronic apparatus, wherein the drive source and/or the energy storage source of the electronic apparatus is the electrochemical device described above.
According to the active carbon electrode provided by the embodiment of the invention, lithium is supplemented to the active carbon electrode by mixing the inorganic lithium salt and the organic lithium salt, the advantages of high gram capacity of the inorganic lithium salt and no residue of the organic lithium salt are simultaneously exerted, enough active lithium ions are provided for a negative electrode corresponding to the active carbon electrode during formation of a film, a stable SEI film is formed, particularly when the active carbon electrode is used for a mixed lithium ion storage battery/capacitor battery, the low-temperature performance, the first effect, the cycle performance and the storage performance of the battery can be improved, the service life of the mixed lithium ion storage battery/capacitor battery is prolonged, and the application range of the mixed lithium ion storage battery/capacitor battery is widened.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention provides an activated carbon electrode, which comprises a current collector and a carbon active layer attached to at least one functional surface of the current collector, wherein the carbon active layer comprises 70-95% of activated carbon, 1-30% of lithium salt and 0-10% of functional additive in percentage by mass;
the lithium salt includes organic lithium salt and inorganic lithium salt.
The functional surfaces are the upper surface and the lower surface of the current collector, and the active carbon electrode can be a current collector with a carbon active layer attached to any one of the upper surface and the lower surface, or a current collector with a carbon active layer attached to both the upper surface and the lower surface.
The functional additive comprises a conductive agent and a binder, wherein the conductive agent comprises conductive carbon black, and the binder comprises polyvinylidene fluoride (PVDF). In some embodiments, the carbon active layer comprises, by mass, 70% to 95% of activated carbon, 1% to 30% of lithium salt, 0% to 10% of conductive carbon black, and 0% to 10% of PVDF.
According to the invention, the inorganic lithium salt and the organic lithium salt are blended to supplement lithium for the activated carbon electrode, so that the advantages of high gram capacity of the inorganic lithium salt and no residue of the organic lithium salt can be simultaneously played, enough active lithium ions are provided for a negative electrode corresponding to the activated carbon electrode during formation of a film, and a stable SEI film is formed.
In some embodiments of the invention, the carbon active layer comprises, by mass percent, 85% to 89% activated carbon, 5% to 7% lithium salt, 3% to 4% conductive carbon black, 3% to 4% PVDF.
The active carbon electrode depends on the porous active carbon to adsorb PF in electrolyte during charging and discharging6 -、TFSI-、FSI-And the rest anions are waited, so the content of the active carbon in the carbon active layer of the active carbon electrode is not too low; the negative electrode corresponding to the activated carbon electrode needs enough activated lithium ions, and the carbon active layer needs to be ensured to have enough lithium salt. Therefore, the content of the mixed lithium salt in the carbon active layer is reasonably set, so that enough lithium salt is provided for the activated carbon electrode, enough activated lithium ions are generated when the negative electrode corresponding to the activated carbon electrode is formed into a film, a stable SEI film is formed, and enough activated carbon in the carbon active layer of the activated carbon electrode can be ensured to adsorb anions in an electrolyte. The content of the mixed lithium salt in the activated carbon layer is reasonably set, and the invention further disclosesThe effect of the lithium salt on the active carbon electrode is exerted to a large extent. When the activated carbon electrode is used for a mixed lithium ion storage battery/capacitor battery, the low-temperature performance, the first effect, the cycle performance and the storage performance of the battery are further improved, and the service life of the mixed lithium ion storage battery/capacitor battery is further prolonged.
In some embodiments of the present invention, the inorganic lithium salt is selected from Li5FeO4、LiAlO2、Li3AsO4、Li3BO3、Li2CO3、Li2GeO3、Li3PO4、Li2SO4、Li2SeO4、Li2SiO3And Li2TeO3At least one of (1).
Primary inorganic lithium salt (Li)5FeO4) Is a lithium metal oxide with an inverse fluorite structure, has very high specific capacity, the gram capacity of the lithium metal oxide is as high as 700mAh/g, and each molecule can release four Li during formation+The equation is as follows:
Li5FeO4→4Li++4e-+LiFeO2+O2
however, the inorganic lithium salt produces LiFeO as a product after the reaction2The active carbon electrode is retained in the active carbon electrode, and the active carbon electrode depends on the porous active carbon to adsorb PF in electrolyte through physics during charging and discharging6 -、TFSI-、FSI-Wait for the remaining anions, so that LiFeO remains2The activated carbon may be plugged to some extent, thereby affecting the power performance of the hybrid lithium ion battery/capacitor cell.
Therefore, in the embodiment of the present invention, Li having a very high specific capacity is selected5FeO4Mixing with organic lithium salt in reasonable proportion by combining with Li5FeO4The high specific capacity and no residue after the reaction of the organic lithium salt, so as to improve the low-temperature performance, the first effect, the cycle performance and the storage performance of the hybrid lithium ion storage battery/capacitor battery and prolong the service life of the hybrid lithium ion storage battery/capacitor battery.
In some embodiments of the present invention, the organic lithium salt is at least one selected from the group consisting of azide-based lithium salts, oxycarbide-based lithium salts, dicarboxylic acid-based lithium salts, and hydrazide-based lithium salts.
In some embodiments of the present invention, the organic lithium salt is at least one selected from the group consisting of 2-cyclopropene-1-one-2, 3-dihydroxylithium, 3-cyclobutene-1, 2-dione-3, 4-dihydroxylithium, 4-cyclopentene-1, 2, 3-trione-4, 5-dihydroxylithium, 5-cyclohexene-1, 2,3, 4-tetraone-5, 6-dihydroxylithium, lithium oxalate, lithium ketopropionate, lithium diketosuccinate, and lithium trione glutarate.
In some embodiments of the present invention, in the lithium salt, the content of the inorganic lithium salt is 20% to 70% by mass; further, in the lithium salt, the mass percentage of the inorganic lithium salt is 50-70%.
Because the inorganic lithium salt has the advantage of high gram capacity and the organic lithium salt has the advantage of no residue, the invention uses the blending of the inorganic lithium salt and the organic lithium salt to supplement lithium for the activated carbon electrode, but when the inorganic lithium salt is blended with the organic lithium salt, if the content of the inorganic lithium salt is too high, the production product of the inorganic lithium salt is more retained in the activated carbon electrode after the reaction, and the hole plugging is carried out on the activated carbon to a certain degree, thereby influencing the power performance of the mixed lithium ion storage battery/capacitor battery; when the content of the inorganic lithium salt is too low, a large amount of organic lithium salt needs to be added, the organic lithium salt is low in gram capacity, a large amount of gas is generated due to the addition of the organic lithium salt, the lithium ion supplement is not facilitated, and potential safety hazards exist.
Therefore, the invention gives play to the advantages of high gram capacity of inorganic lithium salt and no residue of organic lithium salt to a greater extent by reasonably setting the content of the inorganic lithium salt and the organic lithium salt in the mixed lithium salt, provides enough active lithium ions for the negative electrode corresponding to the active carbon electrode during formation of a film to form a stable SEI film, and improves the low-temperature performance, the first effect, the cycle performance and the storage performance of the battery to a greater extent and prolongs the service life of the mixed lithium ion storage battery/capacitor battery when the active carbon electrode is used for the mixed lithium ion storage battery/capacitor battery.
Furthermore, the mass percentage of the inorganic lithium salt is set to be 50-70%, so that enough inorganic lithium salt with high gram capacity can be provided, and excessive production products cannot be retained in the activated carbon electrode to block the pores of the activated carbon electrode. The advantages of inorganic lithium salt and organic lithium salt can be exerted to the greatest extent, the low-temperature performance, the first effect, the cycle performance and the storage performance of the hybrid lithium ion storage battery/capacitor are improved to a greater extent, and the service life of the hybrid lithium ion storage battery/capacitor battery is prolonged.
A second aspect of the present invention provides an electrochemical device comprising the above-described activated carbon electrode.
In some embodiments of the invention, the electrochemical device is a hybrid lithium ion battery/capacitor cell.
The hybrid lithium ion battery/capacitor cell of the present invention has at least one pair of a graphite negative electrode and an activated carbon electrode, the graphite negative electrode and the activated carbon electrode being disposed opposite to each other. The hybrid lithium ion battery/capacitor cell of the present invention may comprise a wound hybrid lithium ion battery/capacitor cell or a laminated hybrid lithium ion battery/capacitor cell.
When the hybrid lithium ion storage battery/capacitor battery is formed, the activated carbon electrode provides lithium ions for the corresponding negative electrode, physical adsorption occurs on the activated carbon electrode, and electrochemical reaction occurs on the graphite negative electrode. The hybrid lithium ion storage battery/capacitor battery combines the advantages of a lithium ion battery and a capacitor, has good low-temperature performance, first effect, cycle performance and storage performance, and has a wide application range in daily life.
In some embodiments of the present invention, the above method of making a hybrid lithium ion battery/capacitor cell comprises the steps of:
1) mixing the activated carbon material, the conductive agent, the binder and the lithium salt according to a certain proportion, adding N-methyl pyrrolidone, stirring and dispersing to prepare the carbon active layer slurry. And then coating the double surfaces of the carbon active layer slurry on an active carbon electrode current collector, drying, slitting and flaking to prepare the active carbon electrode.
2) Mixing the positive active material, the conductive agent and the binder according to a certain proportion, adding N-methyl pyrrolidone, stirring and dispersing to prepare positive active layer slurry. And then coating the two sides of the positive active layer slurry on a positive current collector, drying, slitting and preparing a sheet to obtain the positive pole piece.
3) Mixing the negative active material, the conductive agent, the binder and the thickening agent according to a certain proportion, adding deionized water, stirring and dispersing to prepare negative active layer slurry. And then coating the two sides of the slurry of the negative active layer on a negative current collector, drying, slitting and preparing a sheet to obtain the negative pole piece.
4) Preparing a certain amount of the activated carbon electrode prepared in the first step, the positive pole piece prepared in the second step and the negative pole piece prepared in the third step, a diaphragm and an aluminum-plastic film into an electrode assembly, then performing the procedures of liquid injection, aging, formation, pre-circulation and the like, and finally testing the electrochemical performance of the battery.
The preparation parameters of the carbon active layer in the step 1) are selected from the preparation parameters of the carbon active layer provided by the first aspect of the invention.
The positive active material in the step 2) includes but is not limited to one or more of lithium cobaltate, ternary material, lithium manganate and lithium iron phosphate; the conductive agent includes conductive carbon black; the binder comprises PVDF.
In some embodiments, the positive active layer comprises, by mass, 0% to 10% of conductive carbon black, 0% to 10% of PVDF, and the balance of a positive active material. Further, the positive active layer comprises 3-4% of conductive carbon black, 3-4% of PVDF and the balance of positive active materials in percentage by mass.
The negative active material in the step 3) includes, but is not limited to, one or more of carbon materials, silicon and compounds thereof, lithium titanate, tin and compounds thereof; the conductive agent includes conductive carbon black; the binder comprises Styrene Butadiene Rubber (SBR); the thickener comprises sodium carboxymethylcellulose.
In some embodiments, the negative active layer comprises, by mass, 0% to 10% of conductive carbon black, 0% to 10% of SBR, 0% to 10% of a thickener, and the balance of a negative active material. Further, the negative active layer comprises, by mass, 2% -3% of conductive carbon black, 0.8% -1.8% of SBR, 0% -10% of a thickening agent, and the balance of a negative active material.
The active carbon electrode in the step 4) accounts for 0.1-10% of the total number of all the pole pieces. Furthermore, the active carbon electrode accounts for 1.5-3% of the total number of all pole pieces.
The pre-circulation in the step 4) needs to be charged and discharged for 5-100 times by using a clamping plate and an air bag, and the purpose is to fully consume the lithium supplement material.
The step 4) of injecting liquid is to inject an electrolyte into the aluminum plastic film, and the electrolyte may include a lithium salt and a non-aqueous solvent. In the present invention, the lithium salt is not particularly limited, and any lithium salt known in the art may be used as long as the object of the present invention can be achieved. For example, the lithium salt may include LiPF6、LiBF4、LiAsF6、LiClO4、LiB(C6H5)4、LiCH3SO3、LiCF3SO3、LiN(SO2CF3)2、LiC(SO2CF3)3Or LiPO2F2At least one of (1). In the present invention, the nonaqueous solvent is not particularly limited as long as the object of the present invention can be achieved. For example, the non-aqueous solvent may include at least one of a carbonate compound, a carboxylate compound, an ether compound, a nitrile compound, and other organic solvents.
In a third aspect of the present invention, there is provided an electronic apparatus, wherein the driving source and/or the energy storage source of the electronic apparatus is the electrochemical device described above.
The electrochemical device may be used as a power source for electronic equipment, and may also be used as an energy storage unit for the electronic equipment. The electronic devices may include, but are not limited to, mobile devices (e.g., mobile phones, notebook computers, etc.), electric vehicles (e.g., electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, and the like.
The active carbon electrode can provide active lithium ions for the negative electrode corresponding to the active carbon electrode in the hybrid lithium ion storage battery/capacitor battery, and the low-temperature performance, the first effect, the cycle performance and the storage performance of the hybrid lithium ion storage battery/capacitor battery are improved; when the active carbon electrode is prepared, the amount of the added mixed lithium is accurately controlled by adjusting the proportion of the added mixed lithium, so that a stable SEI film which is beneficial to lithium ion transmission is easily formed on a negative electrode corresponding to the active carbon electrode, the SEI film is more stable in the circulation or storage process of the mixed lithium ion storage battery/capacitor battery, and the low-temperature performance, the first effect, the circulation performance and the storage performance of the mixed lithium ion storage battery/capacitor battery are further improved; the active carbon electrode is simple and convenient in the lithium supplement process, and is suitable for large-scale production of hybrid lithium ion storage battery/capacitor batteries.
The mixed lithium ion storage battery/capacitor battery prepared by the invention has good low-temperature performance, first effect, cycle performance and storage performance, and has a wide application range in daily life.
The driving source and/or the energy storage source of the electronic equipment provided by the invention have high low-temperature performance, first effect, cycle performance and storage performance, and the electronic equipment has good endurance and service life.
In the embodiment of the present invention, the electrochemical device is realized by taking a hybrid lithium-ion secondary battery/capacitor cell as an example of the electrochemical device, but the electrochemical device is not limited to the hybrid lithium-ion secondary battery/capacitor cell.
Hereinafter, embodiments of the present invention will be described in more detail with reference to examples and comparative examples. Various tests and evaluations were carried out according to the following methods. Unless otherwise specified, "part" and "%" are based on mass.
Example 1
1) Preparation of activated carbon electrode P1
Mixing 86% of activated carbon, 4% of PVDF, 4% of conductive carbon black and 6% of lithium salt according to mass percentage, and stirring at high speed to obtain a uniformly dispersed mixture. The lithium salt has a composition of Li5FeO4With 3-cyclobutene-1, 2-dione-3, 4-dihydroxylithium by massMixed lithium salts mixed in a ratio of 5: 5. Carbon active layer slurry was prepared using N-methylpyrrolidone as a solvent, and the solid content in the slurry was 70 wt%. The slurry was uniformly coated on both sides of the aluminum foil, dried and compacted in a roller press to give an activated carbon electrode designated P1.
2) Preparation of positive electrode sheet B1
92% of lithium iron phosphate (LFP), 4% of PVDF and 4% of conductive carbon black are mixed according to the mass percentage, and the mixture which is uniformly dispersed is obtained by high-speed stirring. N-methylpyrrolidone was used as a solvent to prepare a slurry of the positive electrode active layer, the solid content of the slurry being 70 wt%. The slurry was uniformly coated on both sides of aluminum foil, dried and compacted with a roller press to obtain a positive electrode sheet B1.
3) Preparation of negative pole piece N1
According to the mass percentage, 95 percent of artificial graphite, 1.8 percent of SBR, 1.2 percent of sodium carboxymethylcellulose and 2 percent of conductive carbon black are mixed and stirred at high speed to obtain a uniformly dispersed mixture. Deionized water is used as a solvent to prepare cathode active layer slurry, and the solid content in the slurry is 50 wt%. The slurry was uniformly coated on both sides of copper foil, dried and compacted with a roll press to obtain a negative electrode sheet N1.
4) Assembly of battery
After two pieces of activated carbon electrodes P1, 25 pieces of positive pole pieces B1 and 28 pieces of negative pole pieces N1 are taken and punched, an electrode assembly is formed by sequentially overlapping the negative pole pieces, the activated carbon electrodes, the negative pole pieces, the positive pole pieces, the negative pole pieces, the positive pole pieces … …, the negative pole pieces, the activated carbon electrodes and the negative pole pieces, the positive pole pieces and the activated carbon electrodes are rolled out to form aluminum tabs, the negative pole pieces are rolled out to form copper nickel-plated tabs, and the aluminum-plastic films are used.
The electrolyte adopts 1M lithium hexafluorophosphate electrolyte, and the solvent is a mixed solvent of ethylene carbonate, dimethyl carbonate and 1, 2-propylene carbonate with the volume ratio of 1:1: 1. Injecting electrolyte into the aluminum plastic film, packaging and injecting the electrolyte, then carrying out first-step formation on the battery, charging the battery to 3.0V at the temperature of 68 ℃ by using 0.2C current, then charging the battery to 3.65V by using 0.5C current, then pre-circulating the battery with the clamping plate for 10 times, cutting the opening of the air bag, exhausting air and sealing the opening again. Aging at 80 deg.C for 20min, cutting off the air bag, and sealing the cut. Finally, the square flexible package mixed lithium ion storage battery/capacitor battery with the length, width and thickness of 121mm multiplied by 6.5mm is obtained.
Example 2
Except that the lithium salt is Li in the preparation of the active carbon electrode5FeO4The procedure was repeated except for using a lithium salt mixture containing lithium oxalate and lithium salt in a mass ratio of 5:5 in the same manner as in example 1.
Example 3
Except that the lithium salt is Li in the preparation of the active carbon electrode5FeO4The procedure of example 1 was repeated except for using a lithium salt mixture containing lithium ketomalonate and lithium ketomalonate in a mass ratio of 5: 5.
Example 4
Except that the lithium salt is Li in the preparation of the active carbon electrode5FeO4The procedure of example 1 was repeated except for using a lithium salt mixture containing lithium diketosuccinate in a mass ratio of 6: 4.
Example 5
Except that the lithium salt is Li in the preparation of the active carbon electrode5FeO4The procedure of example 1 was repeated, except for using a mixed lithium salt of 3-cyclobutene-1, 2-dione-3, 4-dihydroxylithium in a mass ratio of 6: 4.
Example 6
Except that the lithium salt is Li in the preparation of the active carbon electrode5FeO4The procedure was repeated except for using a mixed lithium salt of 3-cyclobutene-1, 2-dione-3, 4-dihydroxylithium in a mass ratio of 7:3 in the same manner as in example 1.
Example 7
The process was performed in the same manner as in example 1, except that 82% of activated carbon, 4% of PVDF, 4% of conductive carbon black and 10% of lithium salt were mixed in terms of mass% in step 1).
Comparative example 1
Except that the lithium salt is Li in the preparation of the active carbon electrode5FeO4Otherwise, the same procedure as in example 1 was repeated.
Comparative example 2
The same procedure as in example 1 was repeated, except that no lithium salt was added in the preparation of the activated carbon electrode.
Performance testing
1. First-pass test of battery
The first effect is the ratio of the initial discharge capacity to the initial charge capacity.
The detection method comprises the following steps: charging the unformed lithium ion battery to 3.65V at 25 ℃ with 0.2C constant current by using a battery charge-discharge tester (BK-3128LH/4), then charging with constant voltage until the current is reduced to 0.02C, standing for 5min, discharging the battery to 2.2V with 0.2C constant current, recording the first charge capacity Q charge and the first discharge capacity Q discharge of the battery, and calculating the first charge-discharge efficiency eta of the batteryPut/ECharging deviceX 100%,%, test data are shown in table 1.
2. -30 ℃ 50% residual Power (SOC) discharge Voltage test
The detection method comprises the following steps: charging the sorted qualified lithium ion battery to 3.65V at a constant current of 1.0C at 25 ℃ by using a battery charge-discharge tester (SC-408-CC-3), then charging at a constant voltage until the current is reduced to 0.05C, standing for 5min, discharging the battery to 2.2V at a constant current of 1.0C, and recording the capacity C0 of the battery; charging to 3.65V at constant current of 1.0C at 25 deg.C, then charging at constant voltage until the current drops to 0.05C, standing for 5min, discharging the cell to 50% C0 at constant current of 1.0C, recording the 50% SOC of the cell, standing the cell at 50% SOC at-30 deg.C for 4h (until the cell reaches thermal equilibrium), then discharging at-30 deg.C for 10S at 10C, recording the discharge end voltage, V, and the test data are shown in Table 2.
3. 100% SOC stored data test at 60 deg.C
The detection method comprises the following steps: charging the sorted qualified lithium ion battery to 3.65V at a constant current of 1.0C at 25 ℃ by using a battery charging and discharging tester (SC-408-CC-3), then charging at a constant voltage until the current is reduced to 0.05C, standing for 5min, discharging the battery to 2.2V at a constant current of 1.0C, and recording the capacity C0 of the battery cell; charging to 3.65V at constant current of 1.0C at 25 ℃, then charging at constant voltage until the current is reduced to 0.05C, standing at 60 ℃, taking out the battery every 30 days, charging to 3.65V at constant current of 1.0C at 25 ℃, then charging at constant voltage until the current is reduced to 0.05C, standing for 5min, discharging the battery to 2.2V at constant current of 1.0C, and recording the recovery capacity,%, of the battery, wherein the test data are shown in Table 3.
4. 1C/1C 100% depth of discharge (DOD) cycle performance test at high temperature of 55 DEG C
Firstly, charging to 3.65V at a constant current of 1C, then charging at a constant voltage, stopping current of 0.05C, finally discharging to 2.2V at the constant current of 1C, circularly testing until the capacity of the electrode assembly is attenuated to below 70%, recording the capacity of the electrode assembly at certain times, and calculating the retention rate,%, of the capacity and the first capacity of the electrode assembly, wherein the test data are shown in Table 4.
TABLE 1 initial effect (%)
Figure BDA0002755963500000111
As can be seen from table 1, the battery prepared by adding the organic lithium salt and the inorganic lithium salt mixed lithium salt to the active carbon electrode sheet in the embodiment of the present invention has high first efficiency.
TABLE 2 examples and comparative examples 5 cells each were prepared with a discharge voltage (V) of-30 deg.C
Figure BDA0002755963500000112
As can be seen from Table 2, in examples 1 to 7, compared with comparative example 1, the low-temperature discharge performance of the battery in which the inorganic lithium salt and the organic lithium salt mixed salt are added to the activated carbon electrode sheet is better than that of the battery in which only the inorganic lithium salt is added to the activated carbon electrode sheet.
Table 3 storage property (%) -at 60 c of the batteries prepared in examples and comparative examples
Figure BDA0002755963500000121
As can be seen from Table 3, the battery prepared by adding the organic lithium salt and the inorganic lithium salt mixed lithium salt into the active carbon electrode plate in the embodiment of the invention has high-temperature storage performance.
TABLE 4 cyclability (%) -at 55 ℃ of the batteries prepared in examples and comparative examples
Figure BDA0002755963500000122
As can be seen from Table 4, the battery prepared by adding the organic lithium salt and the inorganic lithium salt mixed lithium salt into the active carbon electrode plate in the embodiment of the invention has high-temperature cycle performance.
In conclusion, the mixed salt of the inorganic lithium salt and the organic lithium salt is added into the active carbon electrode plate, so that the cold start effect is good under the condition that the battery has high first effect, storage performance and cycle performance, the comprehensive performance is excellent, the service life of the battery is greatly prolonged, and the application range of the battery is widened.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims (10)

1. An activated carbon electrode is characterized by comprising a current collector and a carbon active layer attached to at least one functional surface of the current collector, wherein the carbon active layer comprises 70-95% of activated carbon, 1-30% of lithium salt and 0-10% of functional additive in percentage by mass;
wherein the lithium salt includes an organic lithium salt and an inorganic lithium salt.
2. The activated carbon electrode according to claim 1, wherein the inorganic lithium salt is selected from Li5FeO4、LiAlO2、Li3AsO4、Li3BO3、Li2CO3、Li2GeO3、Li3PO4、Li2SO4、Li2SeO4、Li2SiO3And Li2TeO3At least one of (1).
3. The activated carbon electrode according to claim 1 or 2, wherein the organic lithium salt is at least one selected from the group consisting of azide-based lithium salts, oxygen-containing carbide-based lithium salts, dicarboxylic acid-based lithium salts, and hydrazide-based lithium salts.
4. The activated carbon electrode according to claim 1 or 2, wherein the organic lithium salt is at least one selected from the group consisting of 2-cyclopropene-1-one-2, 3-dihydroxylithium, 3-cyclobutene-1, 2-dione-3, 4-dihydroxylithium, 4-cyclopentene-1, 2, 3-trione-4, 5-dihydroxylithium, 5-cyclohexene-1, 2,3, 4-tetraone-5, 6-dihydroxylithium, lithium oxalate, lithium ketomalonate, lithium diketosuccinate, and lithium trione glutarate.
5. The activated carbon electrode of any one of claims 1 to 4, wherein the carbon active layer comprises 5% to 7% lithium salt by mass.
6. The activated carbon electrode according to any one of claims 1 to 5, wherein the inorganic lithium salt is contained in an amount of 20 to 70% by mass.
7. The activated carbon electrode according to claim 6, wherein the lithium salt contains 50 to 70 mass% of an inorganic lithium salt.
8. An electrochemical device comprising the activated carbon electrode according to any one of claims 1 to 7.
9. The electrochemical device of claim 8, wherein said electrochemical device is a hybrid lithium ion battery/capacitor cell.
10. An electronic device characterized in that a driving source and/or an energy storage source of the electronic device is the electrochemical device according to claim 8 or 9.
CN202011202806.0A 2020-11-02 2020-11-02 Activated carbon electrode, electrochemical device using the same, and electronic apparatus Pending CN112310393A (en)

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