CN114824161A - Electrochemical device and electronic device - Google Patents

Electrochemical device and electronic device Download PDF

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Publication number
CN114824161A
CN114824161A CN202210322442.2A CN202210322442A CN114824161A CN 114824161 A CN114824161 A CN 114824161A CN 202210322442 A CN202210322442 A CN 202210322442A CN 114824161 A CN114824161 A CN 114824161A
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Prior art keywords
electrochemical device
negative pole
active material
negative
dispersing agent
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Chinese (zh)
Inventor
喻磊
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Ningde Amperex Technology Ltd
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Ningde Amperex Technology Ltd
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Priority to CN202210322442.2A priority Critical patent/CN114824161A/en
Publication of CN114824161A publication Critical patent/CN114824161A/en
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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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/133—Electrodes based on 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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • 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
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • 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
    • 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
    • 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
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes

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

Abstract

The application relates to an electrochemical device and an electronic device, wherein the electrochemical device comprises a negative pole piece, the negative pole piece comprises a negative pole current collector and a negative pole active substance layer arranged on the negative pole current collector, the negative pole active substance layer comprises a negative pole active substance and a composite dispersing agent, the composite dispersing agent comprises a polymer containing carboxyl anions and silicate, and the ionic conductivity of the carboxyl anions and the cation of the silicate is 6 multiplied by 10 when the composite dispersing agent is in a solution state and is associated with a glue film of the composite dispersing agent under the action of static electricity ‑2 ms/cm to 10X 10 ‑ 2 ms/cm. The carboxyl anions and the cations in the silicate are mutually associated through electrostatic interaction, and a cross-linked network structure can be formed, so that the complex can be improvedThe viscosity of the composite dispersing agent is reduced, the using amount of the composite dispersing agent in the negative active material layer is reduced, and the using amount of the negative active material is correspondingly increased, so that the conductivity of the negative active material can be improved, and the electrochemical performance of the electrochemical device is improved.

Description

Electrochemical device and electronic device
Technical Field
The present disclosure relates to the field of energy storage, and more particularly, to an electrochemical device and an electronic device.
Background
The electrochemical device has the characteristics of high energy density, high working voltage, light weight and the like, so that the electrochemical device is widely applied to electronic products such as mobile phones, notebook computers, cameras and the like. The safety performance of the electrochemical device is improved while the electrochemical performance of the electrochemical device is improved. With the improvement of the performance requirements of electronic products, the performance requirements of electrochemical devices are gradually improved.
Research finds that the negative active material is an important component of an electrochemical device, and the performance of the negative active material, particularly the conductivity of the negative active material, has a significant influence on the electrochemical device, so that the improvement of the conductivity of the negative active material is a problem to be solved.
Disclosure of Invention
The application provides an electrochemical device and an electronic device, aiming at improving the electrochemical performance of the electrochemical device by improving the conductivity of a negative active material.
In a first aspect, an embodiment of the present application provides an electrochemical device, which includes a negative electrode tab, where the negative electrode tab includes a negative electrode current collector and a negative electrode active material layer disposed on the negative electrode current collector, the negative electrode active material layer includes a negative electrode active material and a composite dispersant, the composite dispersant includes a polymer containing a carboxyl anion and a silicate, and an adhesive film ionic conductivity of the carboxyl anion and a cation of the silicate for associating the composite dispersant in a solution state and under an electrostatic effect is 6 × 10 -2 ms/cm to 10X 10 -2 ms/cm。
In some embodiments, the carboxyl anion containing polymer comprises a carboxymethyl cellulose salt and/or a hydroxypropyl methyl cellulose salt.
In some embodiments, the carboxyl anion containing polymer has a relative molecular weight of from 40 to 100 ten thousand.
In some embodiments, the cations of the silicate comprise one or more of ammonium, lithium, sodium, and potassium ions.
In some embodiments, the mass ratio of silicate to carboxyl anion containing polymer is (0.025: 1) to (0.3: 1).
In some embodiments, the viscosity of the composite dispersant is 20000 to 50000 mPa-s.
In some embodiments, the composite dispersant is contained in an amount of 0.6 to 1.5% by mass based on the mass of the anode active material layer.
In some embodiments, the composite dispersant has an insoluble gum content of 10ea/(7.5 × 7.5 cm) 2 ) To 50 ea/(7.5X 7.5 cm) 2 )。
In some embodiments, the negative pole piece has an ionic resistance of 15 to 20m Ω.
In a second aspect, embodiments of the present application are directed to an electronic device including an electrochemical device according to any of the embodiments of the first aspect of the present application.
The composite dispersing agent comprises a polymer containing carboxyl anions and silicate, the carboxyl anions and cations in the silicate are mutually associated through electrostatic interaction, and a cross-linked network structure can be formed, so that the viscosity of the composite dispersing agent can be improved, the use amount of the composite dispersing agent in a negative active material layer can be reduced on the basis of ensuring the stability of negative slurry forming the negative active material layer, the use amount of the negative active material is correspondingly increased, and the electrochemical performance of an electrochemical device can be improved. In addition, the ionic conductivity of the glue film of the composite dispersant is 6 multiplied by 10 -2 ms/cm to 10X 10 -2 ms/cm, the conductivity of the composite dispersant is relatively good, so that the conductivity of the negative active material layer can be further improved, the electrochemical performance of the electrochemical device can be further improved, and particularly the low-temperature discharge characteristic and the quick charge capacity of the electrochemical device are remarkably improved.
Detailed Description
Embodiments of the present application will be described in detail below. The embodiments of the present application should not be construed as limiting the present application.
Additionally, amounts, ratios, and other numerical values are sometimes presented herein in a range format. It is to be understood that such range format is used for convenience and brevity, and should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited.
In the detailed description and claims, a list of items linked by the terms "one or more of," "one or more of," or other similar terms may mean any combination of the listed items. For example, if items a and B are listed, the phrase "at least one of a and B" means a only; only B; or A and B. In another example, if items A, B and C are listed, the phrase "at least one of A, B and C" means a only; or only B; only C; a and B (excluding C); a and C (excluding B); b and C (excluding A); or A, B and C. Item a may comprise a single element or multiple elements. Item B may comprise a single element or multiple elements. Item C may comprise a single element or multiple elements.
An embodiment of the application provides an electrochemical device, which comprises a negative pole piece. The negative pole piece comprises a negative pole current collector and a negative pole active substance layer arranged on the negative pole current collector, the negative pole active substance layer comprises a negative pole active substance and a composite dispersing agent, the composite dispersing agent comprises a polymer containing carboxyl anions and silicate, and the ionic conductivity of a glue film of the composite dispersing agent is 6 multiplied by 10 -2 ms/cm to 10X 10 -2 ms/cm。
[ negative electrode sheet ]
The negative electrode active material layer includes a negative electrode active material and a composite dispersant, wherein the negative electrode active material is a core component in the negative electrode active material layer, which participates in an electrochemical reaction during charge and discharge. The composite dispersant is used to uniformly disperse the negative active material.
The negative electrode current collector is provided with a negative electrode active material layer, and can collect and output current generated by the negative electrode active material layer and input the current to the negative electrode active material layer. The negative electrode current collector includes two surfaces opposite to each other in its own thickness direction, and the negative electrode active material layer may be provided on both surfaces, but of course, may be provided on only one of the two surfaces.
The composite dispersing agent comprises a polymer containing carboxyl anions and silicate, wherein the carboxyl anions and cations in the silicate are mutually associated through electrostatic interaction, and a cross-linked network structure can be formed, so that the viscosity of the composite dispersing agent can be improved, the use amount of the composite dispersing agent in a negative active material layer can be reduced on the basis of ensuring the stability of negative slurry for forming the negative active material layer, the use amount of the negative active material is correspondingly increased, and the composite dispersing agent can be used for improving the stability of the negative slurry for forming the negative active material layerThe electrochemical performance of the electrochemical device is improved. In addition, the ionic conductivity of the glue film of the composite dispersant is 6 multiplied by 10 -2 ms/cm to 10X 10 -2 ms/cm, the conductivity of the composite dispersant is relatively good, so that the conductivity of the negative active material layer can be further improved, the electrochemical performance of the electrochemical device can be further improved, and particularly the low-temperature discharge characteristic and the quick charge capacity of the electrochemical device are remarkably improved.
In some embodiments, the carboxyl anion containing polymer comprises a carboxymethyl cellulose salt and/or a hydroxypropyl methyl cellulose salt. The carboxyl anion-containing polymer has certain viscosity, so that the bonding strength between the negative active material and the negative current collector can be improved; and after the composite dispersing agent is associated with cations in silicate, the viscosity of the composite dispersing agent can be further improved, so that the using amount of the negative active material in the negative active material layer is correspondingly reduced.
As an example of a carboxymethyl cellulose salt, the carboxymethyl cellulose salt may include lithium carboxymethyl cellulose CMC-Li and/or sodium carboxymethyl cellulose CMC-Na.
As examples of hydroxypropylmethylcellulose salts, hydroxypropylmethylcellulose salts include lithium hydroxypropylmethylcellulose HPMC-Li and/or sodium hydroxypropylmethylcellulose HPMC-Na.
In some embodiments, the carboxyl anion containing polymer has a relative molecular weight of 40 to 100 ten thousand; further, the relative molecular weight of the polymer is 50 to 70 ten thousand. When the relative molecular weight of the carboxyl anion containing polymer satisfies the above range, the viscosity thereof is high, and the amount of the negative electrode active material used in the negative electrode active material layer can be reduced accordingly.
In some embodiments, the cations of the silicate include one or more of ammonium ions, lithium ions, sodium ions, and potassium ions. The cation is convenient to source and is favorable for being associated with carboxyl anion to form a cross-linked network structure, so that the viscosity of the composite dispersing agent is improved.
In some embodiments, the mass ratio of silicate to carboxyl anion containing polymer is (0.025: 1) to (0.3: 1). Illustratively, the mass ratio of the silicate to the carboxyl anion containing polymer may be (0.025: 1), (0.05: 1), (0.1: 1), (0.15: 1), (0.2: 1), or (0.3: 1).
When the mass ratio of the silicate to the polymer containing carboxyl anions satisfies the above range, the cations containing carboxyl anions and silicate can be sufficiently associated, thereby significantly increasing the viscosity of the composite dispersant; and the quantity of insoluble glue of the composite dispersant is relatively less, so that the rheological property of the negative electrode slurry for forming the negative electrode active material layer is better, the formed negative electrode active material layer is uniform in thickness and level in surface, and the performances of all parts of the negative electrode active material layer are uniform.
In some embodiments, the viscosity of the composite dispersant is 20000 to 50000 mPa-s. The viscosity of the composite dispersant is relatively high, the quantity of non-sol contained in the composite dispersant is relatively small, and the coating performance of negative electrode slurry for forming a negative electrode active material layer can be improved; and the using amount of the negative electrode active material in the negative electrode active material layer can be correspondingly further improved, so that the electrical property of the negative electrode active material layer is further improved, and the low-temperature discharge characteristic and the quick charge capacity of the electrochemical device are further improved.
In some embodiments, the composite dispersant is contained in an amount of 0.6 to 1.5% by mass based on the mass of the anode active material layer. The usage amount of the composite dispersant is relatively low, and the usage amount of the negative active material can be correspondingly increased, so that the electrical property of the negative active material layer is further improved, and the low-temperature discharge characteristic and the quick charge capacity of the electrochemical device are further improved. The slurry for forming the negative electrode active material layer can be uniformly applied while maintaining stability even when the composite dispersant is added in the above content range.
In some embodiments, the composite dispersant has an insoluble gum content of 10ea/(7.5 × 7.5 cm) 2 ) To 50 ea/(7.5X 7.5 cm) 2 ). The quantity of the insoluble solution in the composite dispersant is relatively less, which is beneficial to further improving the rheological property of the negative electrode slurry for forming the negative electrode active material layer, the formed negative electrode active material layer has uniform thickness and level surface, and each part of the negative electrode active material layerThe performance is uniform.
In some embodiments, the negative pole piece has an ionic resistance of 15 to 20m Ω. The negative pole piece has relatively low ionic resistance, and is favorable for improving the electrical property of the negative pole piece, so that the low-temperature discharge characteristic and the quick charge capacity of the electrochemical device are further improved.
In some embodiments, the structure of the negative electrode tab is a structure of a negative electrode tab known in the art that can be used in an electrochemical device.
In some embodiments, the negative current collector is a metal such as, but not limited to, copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, or combinations thereof.
In some embodiments, the negative active material may be selected from a conventionally known material capable of reversibly intercalating and deintercalating active ions or a conventionally known material capable of reversibly doping and dedoping active ions, which is known in the art and can be used as a negative active material for an electrochemical device. The negative electrode active material contains at least one of lithium metal, a lithium metal alloy, a carbon material, a material capable of doping/dedoping lithium, or a transition metal oxide. In some embodiments, the carbon material may be selected from various carbon materials known in the art that may be used as a carbon-based negative electrode active material for an electrochemical device. In some embodiments, the carbon material comprises at least one of crystalline carbon, amorphous carbon. In some embodiments, the crystalline carbon is natural graphite or artificial graphite. In some embodiments, the crystalline carbon is in the shape of an amorphous form, a plate, a platelet, a sphere, or a fiber. In some embodiments, the crystalline carbon is low crystalline carbon or high crystalline carbon. In some embodiments, the low crystalline carbon comprises at least one of soft carbon, hard carbon. In some embodiments, the high crystalline carbon comprises at least one of natural graphite, crystalline graphite, pyrolytic carbon, mesophase pitch-based carbon fibers, mesophase carbon microbeads, mesophase pitch, high temperature calcined carbon.
In some embodiments, the high temperature calcined carbon is petroleum or coke derived from coal tar pitch. In some embodiments, the amorphous carbon comprises at least one of soft carbon, hard carbon, mesophase pitch carbonization product, fired coke. In some embodiments, the negative active material comprises a transition metal oxide. In some embodiments, the transition metal oxide comprises at least one of vanadium oxide, lithium vanadium oxide. In some embodiments, the negative active material comprises at least one of Si, SiOx (0< x <2), a Si/C composite, a Si-Q alloy, Sn, SnOz, a Sn-C composite, and a Sn-R alloy, wherein Q is selected from at least one of an alkali metal, an alkaline earth metal, a group 13 to group 16 element, a transition element, and a rare earth element and Q is not Si, R is selected from at least one of an alkali metal, an alkaline earth metal, a group 13 to group 16 element, a transition element, and a rare earth element and R is not Sn. In some embodiments, Q and R comprise at least one of Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Tl, Ge, P, As, Sb, Bi, S, Se, Te, Po.
In some embodiments, the anode active material layer further includes an anode binder and an anode conductive agent. In some embodiments, the negative electrode binder comprises at least one of vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene fluoride, polyacrylonitrile, polymethylmethacrylate, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy, nylon. In some embodiments, the negative electrode conductive agent is used to provide conductivity to the electrode, which may include any conductive material as long as it does not cause a chemical change. In some embodiments, the negative electrode conductive agent includes any one of a carbon-based material, a metal-based material, a conductive polymer, or a mixture thereof. In some embodiments, the carbon-based material comprises at least one of natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber. In some embodiments, the metal-based material comprises at least one of metal powder or metal fibers of copper, nickel, aluminum, silver, and the like. In some embodiments, the conductive polymer comprises a polyphenylene derivative.
In some embodiments, the negative electrode sheet is prepared by methods known in the art for preparing negative electrodes that can be used in electrochemical devices. In some embodiments, in the preparation of the negative electrode slurry, a solvent is generally added, and the negative electrode active material is dissolved or dispersed in the solvent after adding a binder and a composite dispersant and adding a conductive material as needed to prepare the negative electrode slurry. The solvent is evaporated during the drying process. The solvent is a solvent known in the art, such as, but not limited to, water, which can be used as the negative electrode active material layer.
The mixing ratio of the negative electrode active material, the composite dispersant, and the binder in the negative electrode active material layer is not particularly limited, and may be controlled according to the desired electrochemical device performance. Illustratively, the mass ratio of the artificial graphite to the composite dispersant to the binder is (90-99%): (0.6-1.5%): (0.8% -2%).
[ Positive electrode sheet ]
The electrochemical device of the embodiment of the present application may further include a positive electrode tab. The positive electrode sheet is a positive electrode sheet known in the art that can be used in electrochemical devices. In some embodiments, the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer. The positive electrode active material layer is disposed on a surface of the positive electrode current collector. The positive electrode active material layer contains a positive electrode active material.
In some embodiments, the structure of the positive electrode tab is a structure of a positive electrode tab that can be used in an electrochemical device, as is well known in the art.
In some embodiments, the positive current collector is a metal, such as, but not limited to, aluminum foil.
The positive electrode active material may be any conventionally known material capable of reversibly intercalating and deintercalating active ions, which is known in the art and can be used as a positive electrode active material for an electrochemical device.
In some embodiments, the positive active material includes a composite oxide of lithium and at least one selected from cobalt, manganese, and nickel. Tool for measuringIn particular, the following compounds may be used: using LiCoO 2 、 LiNiO 2 、LiMnO 2 、LiMn 2 O 4 、Li(Ni a Co b Mn c )O 2 (0<a<1，0<b<1，0<c<1， a+b+c＝1)、LiMn 2 O 4 LiNi 1-y Co y O 2 、LiCo l-y Mn y O 2 、LiNi l- y Mn y O 2 (0<y<1)、Li (Ni a Mn b Co c )04(0<a<2，0<b<2，0<c<2，a+b+c＝2)、LiMn 2-z Ni z O 4 、LiMn 2- z Co z O 4 (0<z<2)、Li(Ni a Co b Al c )O 2 (0<a<1，0<b<1，0<c<1，a+b+c＝1)、 LiCoPO 4 And LiFePO 4 At least one kind of (b), or a mixture of two or more kinds of (b). In some embodiments, the positive active material further comprises at least one of a sulfide, a selenide, and a halide.
In some embodiments, the positive electrode active material layer further includes a positive electrode binder and a positive electrode conductive agent. The positive electrode binder is used to improve the binding properties between positive electrode active material particles and between the positive electrode active material particles and a current collector. In some embodiments, the positive electrode binder comprises at least one of polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide containing polymers, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene butadiene rubber, acrylated styrene butadiene rubber, epoxy, nylon. The positive electrode conductive agent is used to provide conductivity to the electrode, and may include any conductive material as long as it does not cause a chemical change. In some embodiments, the positive electrode conductive agent is at least one of natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber, metal powder, metal fiber, and polyphenylene derivative. In some embodiments, the metal in the metal powder and the metal fiber comprises at least one of copper, nickel, aluminum and silver.
In some embodiments, the method for preparing the positive electrode sheet is a method for preparing a positive electrode sheet that can be used in an electrochemical device, which is well known in the art. In some embodiments, in the preparation of the positive electrode slurry, a solvent is generally added, and the positive electrode active material is dissolved or dispersed in the solvent after adding a binder and, if necessary, a conductive material and a thickener to prepare the positive electrode slurry. The solvent is evaporated during the drying process. The solvent is a solvent known in the art that can be used as the positive electrode active material layer, and is, for example, but not limited to, N-methylpyrrolidone (NMP).
[ isolation film ]
The electrochemical device of the embodiment of the application can further comprise an isolating membrane, wherein the isolating membrane is arranged between the positive pole piece and the negative pole piece so as to separate the positive pole piece and the negative pole piece and reduce the risk of direct contact between the negative pole and the positive pole. The negative electrode, the separator, and the positive electrode have various structural forms, for example, the negative electrode, the separator, and the positive electrode are sequentially stacked to be disposed in a lamination type structure, or the negative electrode, the separator, and the positive electrode are wound to form a winding type structure.
The separator is a separator known in the art that can be used for an electrochemical device, such as, but not limited to, polyolefin-based microporous membranes. In some embodiments, the barrier film comprises at least one of Polyethylene (PE), ethylene propylene copolymer, polypropylene (PP), ethylene-butene copolymer, ethylene-hexene copolymer, ethylene-methyl methacrylate copolymer.
In some embodiments, the separator is a single layer separator or a multilayer separator.
In some embodiments, the release film is coated with a coating. In some embodiments, the coating comprises at least one of an organic coating selected from at least one of polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polyacrylonitrile, polyimide, acrylonitrile-butadiene copolymer, acrylonitrile-styrene-butadiene copolymer, polymethyl methacrylate, polymethyl acrylate, polyethylacrylate, acrylic acid-styrene copolymer, polydimethylsiloxane, sodium polyacrylate, sodium carboxymethylcellulose, and an inorganic coating selected from at least one of polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polyacrylonitrile, polyimide, acrylonitrile-butadiene copolymer, acrylonitrile-styrene-butadiene copolymer, polymethyl methacrylate, polymethyl acrylate, polyethylacrylate, acrylic acid-styrene copolymer, polydimethylsiloxane, sodium polyacrylate, and sodium carboxymethylcelluloseThe layer is selected from SiO 2 、Al 2 O 3 、CaO、TiO 2 、ZnO 2 、 MgO、ZrO 2 、SnO 2 At least one of them.
The form and thickness of the separator are not particularly limited. The method for preparing the separator is a method for preparing a separator that can be used in an electrochemical device, which is well known in the art.
[ electrolyte ]
The electrochemical device of the embodiment of the present application may further include an electrolyte. The electrolyte solution of the present application contains an electrolyte salt. The electrolyte salt is well known in the art as an electrolyte salt suitable for an electrochemical device. For different electrochemical devices, suitable electrolyte salts may be selected. For example, for lithium ion batteries, lithium salts are commonly used as electrolyte salts.
In some embodiments, the lithium salt comprises or is selected from at least one of an organic lithium salt and an inorganic lithium salt.
In some embodiments, the lithium salt comprises or is selected from lithium hexafluorophosphate (LiPF) 6 ) Lithium hexafluoroantimonate (LiSbF) 6 ) Lithium hexafluoroarsenate (LiAsF) 6 ) Lithium perfluorobutylsulfonate (LiC) 4 F 9 SO 3 ) Lithium perchlorate (LiClO) 4 ) Lithium aluminate (LiAlO) 2 ) Lithium aluminum tetrachloride (LiAlCl) 4 ) Lithium bis (fluorosulfonylimide) (LiN (C) x F 2x+1 SO 2 )(C y F 2y+1 SO 2 ) Wherein x and y are natural numbers), lithium chloride (LiCl), or lithium fluoride (LiF). In some embodiments, the lithium salt is present in the electrolyte of the present application in an amount of 10 wt% to 15 wt%, for example 10%, 11%, 12%, 13%, 14%, 15% or any range therebetween.
The electrolyte solution of the present application may further include a non-aqueous organic solvent, and in some embodiments, the non-aqueous organic solvent includes at least one of carbonate, carboxylate, ether compound, sulfone compound, or other aprotic solvent. In some embodiments, the non-aqueous organic solvent is present in an amount of 21% to 90% by weight, and may be, for example, 21%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or any range therebetween.
In some embodiments, the carbonate solvent comprises at least one of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, propyl ethyl carbonate, dipropyl carbonate, ethylene carbonate, propylene carbonate, butylene carbonate, bis (2,2, 2-trifluoroethyl) carbonate.
In some embodiments, the carboxylate solvent comprises at least one of methyl acetate, ethyl acetate, n-propyl acetate, n-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate, butyl butyrate, γ -butyrolactone, valerolactone, butyrolactone.
In some embodiments, the ether compound solvent comprises at least one of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, dibutyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, bis (2,2, 2-trifluoroethyl) ether, 1, 3-dioxane, 1, 4-dioxane.
In some embodiments, the sulfone compound comprises at least one of ethyl vinyl sulfone, methyl isopropyl sulfone, isopropyl sec-butyl sulfone, sulfolane.
The nonaqueous organic solvent in the electrolyte solution may be a single nonaqueous organic solvent or a mixture of plural nonaqueous organic solvents, and when a mixed solvent is used, the mixing ratio may be controlled according to the desired electrochemical device performance.
The electrolyte solution of the present application may further contain functional additives, such as a film-forming additive and a positive electrode film-forming additive. The film-forming additive can form an interface film on the surface of the negative pole piece and/or the positive pole piece, so that the negative pole piece and/or the positive pole piece are protected. In some embodiments, the film-forming additive may be a polynitrile additive, a sulfonate additive, or the like.
Based on the same inventive concept, the application also provides an electronic device.
The electronic device of the present application is any electronic device such as, but not limited to, a notebook computer, a pen-input computer, a mobile computer, an electronic book player, a portable telephone, a portable facsimile, a portable copier, a portable printer, a headphone, a video recorder, a liquid crystal television, a handy cleaner, a portable CD player, a mini disc, a transceiver, an electronic notebook, a calculator, a memory card, a portable recorder, a radio, a backup power source, a motor, an automobile, a motorcycle, a power-assisted bicycle, a lighting fixture, a toy, a game machine, a clock, an electric tool, a flashlight, a camera, a large-sized household battery, and a lithium ion capacitor. Note that the electrochemical device of the present application is applicable to an energy storage power station, a marine vehicle, and an air vehicle, in addition to the above-exemplified electronic devices. The air transport carrier device comprises an air transport carrier device in the atmosphere and an air transport carrier device outside the atmosphere.
In some embodiments, the electronic device comprises an electrochemical device as described herein.
The technical solution of the present application is further described below by taking a lithium ion battery as an example and combining a comparative example and an example, but is not limited thereto. It will be understood by those skilled in the art that the preparation methods described in the present application are only exemplary embodiments, and all modifications or substitutions to the technical solutions of the present application without departing from the scope of the technical solutions of the present application should be covered in the protection scope of the present application.
In the following examples and comparative examples, reagents, materials and instruments used were commercially available or synthetically available, unless otherwise specified.
Examples 1 to 13, comparative examples 1 and 2
Preparation of lithium ion battery
(1) Preparation of positive pole piece
The positive electrode active material lithium cobaltate (LiCoO) 2 ) Mixing acetylene black serving as a conductive agent and polyvinylidene fluoride (PVDF) serving as a binder according to a mass ratio of 96:2:2, adding N-methylpyrrolidone (NMP), and uniformly stirring under the action of a vacuum stirrer to obtain anode slurry; uniformly coating the positive electrode slurry on a positive electrode current collector aluminum foil; and drying the aluminum foil, then carrying out cold pressing, cutting and slitting, and drying under a vacuum condition to obtain the positive pole piece.
(2) Preparation of negative pole piece
Mixing the total mass of the artificial graphite serving as the negative active material and the dispersing agent, acetylene black serving as the conductive agent and Styrene Butadiene Rubber (SBR) serving as the binder according to the mass ratio of 96:2:2, adding deionized water, and obtaining negative slurry under the action of a vacuum stirrer; uniformly coating the negative electrode slurry on a copper foil of a negative electrode current collector; and drying the copper foil, and then drying the copper foil under a vacuum condition after cold pressing, cutting and slitting to obtain the negative pole piece. Wherein, the mass percentage content of the dispersant based on the mass of the negative electrode active material layer is shown in table 1.
The dispersant of the comparative example was a lithium carboxymethyl cellulose solution, which was specifically prepared as follows: 1 part of carboxymethyl cellulose lithium powder with the molecular weight of about 50 ten thousand is dispersed in 399 parts of deionized water, and the mixture is stirred for 4 hours by a double-planet stirrer with revolution of 20rpm and rotation of 1000rpm to obtain transparent CMC dispersant solution.
The dispersant of the embodiment adopts a composite dispersant, and the specific preparation process comprises the following steps: dispersing the polymer containing carboxyl anion in deionized water, and stirring for 4h by using a double-planet stirrer revolving at 20rpm and rotating at 1000rpm to obtain a transparent carboxymethyl cellulose lithium dispersant solution.
Dispersing silicate powder in deionized water, and stirring for 0.5h by using a double planetary stirrer revolving at 20rpm and rotating at 1000rpm to obtain a transparent silicate solution.
Adding the silicate solution into a polymer solution containing carboxyl anions, and stirring for 1h by using a double-planet stirrer with revolution of 20rpm and rotation of 1000rpm to obtain a composite dispersant solution of 30000-50000 mPas. The raw materials of the composite dispersant solution and the contents of the raw materials are shown in table 1.
Table 1 components and related parameters of the examples and comparative examples
Figure BDA0003572255580000121
(3) Preparation of electrolyte
In a dry argon atmosphere glove box, ethylene carbonate was addedEster (EC), Propylene Carbonate (PC) and diethyl carbonate (DEC) in a mass ratio of 1: 1: 1, dissolving and fully stirring the mixture, and then adding lithium salt LiPF 6 And mixing uniformly to obtain the electrolyte. Wherein, LiPF 6 The concentration of (2) is 1.00 mol/L.
(4) Preparation of the separator
The single-side ceramic coating and the double-side water-based vinylidene fluoride-hexafluoropropylene copolymer coating are adopted as the isolating film.
(5) Preparation of lithium ion battery
And stacking the anode, the isolating film and the cathode in sequence to enable the isolating film to be positioned between the anode and the cathode to play an isolating role, then winding, welding a tab to obtain a naked battery cell, placing the naked battery cell in an outer packaging foil aluminum plastic film, injecting the prepared electrolyte, and performing vacuum packaging, standing, formation, shaping, capacity test and other processes to obtain the soft package lithium ion battery.
And (4) performance testing:
1. stability of cathode slurry
And (3) placing the cathode slurry in a container at normal temperature, scraping the cathode slurry at the bottom of the container by using an iron sheet or a scraper after 24 hours or 48 hours, and then vertically arranging the iron sheet or the scraper to enable the cathode slurry on the container to flow naturally, wherein if agglomerated cathode slurry is remained on the iron sheet or the scraper and cannot be normally remained, the cathode slurry is settled, otherwise, the cathode slurry is not settled.
2. Molecular weight testing of polymers containing carboxyl anions
Preparing a 1% CMC solution, and subjecting the CMC solution to gel chromatography (GPC) to obtain the CMC number average molecular weight and molecular weight distribution curve.
3. Viscosity testing of polymers containing carboxyl anions
Preparing 1% CMC water solution, setting the rotation speed to 12 revolutions by using a Bohler flying DV1 viscometer, selecting a rotor with a composite measuring range, immersing the rotor into the solution, starting a test, and reading out the viscosity value.
4. Insoluble gel test of composite dispersant
Preparing 1% composite dispersant aqueous solution, and scraping the composite dispersant aqueous solution to polyester PET (polyethylene terephthalate) by using a scraperMembrane (7.5X 7.5 cm) 2 ) And placing the PET film under a polarizing microscope for photographing and testing to obtain the quantity and distribution curve of the insoluble gel.
5. Ionic conductivity of composite dispersant
Forming a glue film with uniform thickness by using a composite dispersing agent through a mould, assembling a stainless steel sheet SS/film/stainless steel sheet SS battery, clamping the glue film between two non-induced steel sheet electrodes, testing by using an electrochemical workstation, wherein the scanning frequency range is 1Hz to 105Hz, obtaining an electrochemical impedance spectroscopy EIS curve, and calculating the ionic conductivity by using the following formula: σ/(Rb × S).
6. Ion resistance of negative pole piece
Preparing an aluminum plastic film packaging bag, a negative pole piece, an isolating membrane and electrolyte, punching the negative pole piece into a size of 23 multiplied by 35mm by using a die, assembling the negative pole piece, the isolating membrane and a pocket into a symmetrical battery in a glove box, dripping two drops of electrolyte, and sealing. The symmetric cell as above was placed on a charge and discharge test channel for testing.
7. H/L (0.2C-20 ℃ C. 3.4V) discharge rate
Fully charging the lithium ion battery, then discharging to 3.4V at 0.2C in a thermostat at 25 ℃, and recording the capacity q 1 (ii) a Then discharging to 3.4V at-20 deg.C in high-low temperature chamber at 0.2C, and recording initial capacity as q 2 . The discharge rate of H/L (0.2C-20 ℃ C. 3.4V) is: (q) a 1 -q 2 )/q 1 *100％。
8. 1.5C @12 ℃ discharge test (lithium analysis test)
Discharging the lithium ion battery, then charging to full charge at 1.5 ℃ in a constant temperature box at 25 ℃, then discharging to 3.0V at 0.5 ℃, repeating 1.5C charging, discharging at 0.5C for 9cls, charging to full charge at 1.5C, disassembling an interface, and taking a picture to observe the condition of lithium precipitation.
9. 1.0C @0 ℃ discharge test (lithium analysis test)
Discharging the lithium ion battery, then charging to full charge at 1.0 ℃ in a high-low temperature box at 0 ℃, then discharging to 3.0V at 0.5 ℃, repeating 1.0C charging, discharging at 0.5C for 9cls, charging to full charge at 1.5C, disassembling an interface, and taking a picture to observe the condition of lithium precipitation.
10. Capacity retention of 500cls at 25 ℃ cycle
Charging and discharging the initial lithium ion battery for 1cls, and recording the initial capacity as q 1 . Charging and discharging 500cls continuously, recording 500cls capacity as q 2 . The capacity retention rate of the polycarbonate at 25 ℃ in 500cls cycle is (q) 1 -q 2 ) /q 1 *100％
And (3) performance test results:
TABLE 2 results of performance test of examples and comparative examples
Figure BDA0003572255580000151
As can be seen from table 2, the dispersant of comparative example 1 and the dispersant of comparative example 2 are not added with a silicate solution, the usage amount of the dispersant is relatively large, the discharge rate is relatively small, and the electrochemical device has a slight lithium precipitation phenomenon during the discharge process, which causes lithium loss, thereby possibly deteriorating the performance of the lithium ion battery.
Compared with comparative examples 1 and 2, in examples 1 to 13, silicate solution is added into the dispersant, and the silicate solution can be associated with carboxyl anions in CMC, so that a cross-linked network structure is generated, the viscosity of the dispersant is improved, the using amount of the dispersant can be reduced, and correspondingly, the using amount of the negative electrode active material can be increased, and the discharge rate of the lithium ion battery is improved. In addition, the negative electrode pastes of examples 1 to 13 have good coating performance, and can form a negative electrode sheet with uniform performance, so that the performance of the lithium ion battery can be remarkably improved.
In examples 1 to 5, the mass ratio of silicate to CMC satisfies (0.025: 1) to (0.3: 1), and the dispersant in the range satisfying the above mass ratio contains relatively less insoluble gum; and the amount of insoluble gel contained in the dispersant is reduced along with the increase of the mass ratio, so that the rheological property of the negative electrode slurry is improved, and the coating performance of the negative electrode slurry is obviously improved.
Examples 1 and 6 each use different silicates, and can improve the viscosity of the dispersant, thereby improving the performance of the negative electrode active material layer.
As can be seen from examples 7 to 10, the higher the molecular weight of CMC, the higher the viscosity of CMC itself, and the higher the binding force between the negative electrode active material layer and the negative electrode current collector can be improved.
In example 1, example 7, and examples 11 to 13, the discharge rate of the lithium ion battery can be significantly improved as the amount of the composite dispersant used is reduced.
Example 1 and example 13 each use different CMCs, and can improve the viscosity of the dispersant, thereby improving the performance of the negative electrode active material layer.
While the present application has been described with reference to preferred embodiments, various modifications may be made and equivalents may be substituted for elements thereof without departing from the scope of the present application, and in particular, features shown in the various embodiments may be combined in any manner as long as there is no structural conflict. The present application is not intended to be limited to the particular embodiments disclosed herein but is to cover all embodiments that may fall within the scope of the appended claims.

Claims (10)

1. The electrochemical device is characterized by comprising a negative pole piece, wherein the negative pole piece comprises a negative pole current collector and a negative pole active substance layer arranged on the negative pole current collector, the negative pole active substance layer comprises a negative pole active substance and a composite dispersing agent, the composite dispersing agent comprises a polymer containing carboxyl anions and silicate, and the ionic conductivity of a glue film of the composite dispersing agent is 6 x 10 -2 ms/cm to 10X 10 -2 ms/cm。
2. The electrochemical device according to claim 1,
the carboxyl anion containing polymer comprises carboxymethyl cellulose salt and/or hydroxypropyl methyl cellulose salt.
3. The electrochemical device according to claim 1,
the relative molecular weight of the carboxyl anion containing polymer is 40 to 100 ten thousand.
4. The electrochemical device of claim 1, wherein the cations of the silicate comprise one or more of ammonium ions, lithium ions, sodium ions, and potassium ions.
5. The electrochemical device according to claim 1,
the mass ratio of the silicate to the carboxyl anion-containing polymer is (0.025: 1) to (0.3: 1).
6. The electrochemical device according to claim 1,
the viscosity of the composite dispersant is 20000 mPas to 50000 mPas.
7. The electrochemical device according to claim 1,
the composite dispersant is contained in an amount of 0.6 to 1.5% by mass based on the mass of the anode active material layer.
8. The electrochemical device according to claim 1,
the quantity of insoluble gel of the composite dispersant is 10ea/(7.5 multiplied by 7.5 cm) 2 ) To 50 ea/(7.5X 7.5 cm) 2 )。
9. The electrochemical device according to any one of claims 1 to 8,
the ionic resistance of the negative pole piece is 15m omega-20 m omega.
10. An electronic device comprising the electrochemical device according to any one of claims 1 to 9.
CN202210322442.2A 2022-03-30 2022-03-30 Electrochemical device and electronic device Pending CN114824161A (en)

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CN111370672A (en) * 2020-03-20 2020-07-03 天津市捷威动力工业有限公司 Preparation method of negative electrode slurry
CN113471412A (en) * 2020-03-31 2021-10-01 北京卫蓝新能源科技有限公司 Composite conductive slurry, preparation method, positive pole piece and lithium ion battery
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JP2014089834A (en) * 2012-10-29 2014-05-15 Nippon Zeon Co Ltd Slurry composition for lithium ion secondary battery negative electrode and manufacturing method thereof, negative electrode for lithium ion secondary battery, and lithium ion secondary battery
CN104393303A (en) * 2014-12-05 2015-03-04 上海空间电源研究所 Lithium titanate battery using waterborne binder
CN106910861A (en) * 2015-12-23 2017-06-30 三星Sdi株式会社 Dividing plate for rechargeable battery and the lithium rechargeable battery including the dividing plate
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