CN106711460B - Electrode slurry composition and application thereof in preparing electrode and lithium ion battery - Google Patents

Electrode slurry composition and application thereof in preparing electrode and lithium ion battery Download PDF

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CN106711460B
CN106711460B CN201611198653.0A CN201611198653A CN106711460B CN 106711460 B CN106711460 B CN 106711460B CN 201611198653 A CN201611198653 A CN 201611198653A CN 106711460 B CN106711460 B CN 106711460B
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electrode
slurry
positive electrode
lithium ion
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CN106711460A (en
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武兆辉
王建涛
庞静
邵泽超
李先季
王琳
高敏
卢世刚
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China Automotive Battery Research Institute 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • H01M4/623—Binders being polymers fluorinated polymers
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
    • 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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Abstract

The invention belongs to the technical field of lithium ion batteries, and particularly relates to a composition for inhibiting interface side reaction of a positive electrode material, and further discloses an electrode prepared from the composition and application of the electrode to a lithium ion battery. According to the electrode slurry composition, PAA is added to modify the electrode slurry composition on the basis of the traditional slurry composition, so that the stability and the dispersion uniformity of the electrode slurry can be effectively improved, the side reaction of the interface reaction of the anode material is further reduced, and the performance of a lithium ion battery is improved.

Description

Electrode slurry composition and application thereof in preparing electrode and lithium ion battery
Technical Field
The invention belongs to the technical field of lithium ion batteries, and particularly relates to a composition for inhibiting interface side reaction of a positive electrode material, and further discloses an electrode prepared from the composition and application of the electrode to a lithium ion battery.
Background
The lithium ion battery is a secondary battery (rechargeable battery) which mainly comprises a positive electrode, a negative electrode, electrolyte, a diaphragm and a shell. The lithium ion secondary battery generally adopts a material containing lithium as an electrode, and mainly depends on lithium ions moving between a positive electrode and a negative electrode to work, and Li is charged and discharged+Intercalation and deintercalation to and from two electrodes: upon charging, Li+The lithium ion battery is extracted from the positive electrode and is inserted into the negative electrode through the electrolyte, and the negative electrode is in a lithium-rich state; the opposite is true during discharge.
The lithium ion battery becomes one of important novel energy sources in a new period due to the advantages of high energy density, high working voltage, long cycle life, small self-discharge and the like, and is a representative of modern high-performance batteries. Particularly, with the wide application of the lithium ion battery in the fields of portable electronic equipment, energy storage power supplies, new energy electric vehicles and the like, the energy density and the safety performance of the lithium ion battery are continuously developed and improved, and meanwhile, higher requirements are provided for the production process of the lithium ion battery.
The preparation process of the electrode of the lithium ion battery is an important link in the production process of the lithium ion battery and mainly comprises two procedures of homogenizing and coating. The electrode slurry of a lithium ion battery is mainly composed of an active material, a conductive agent, a binder and a current collector, and is generally a colloidal mixture formed by adding an electrochemically active material and a conductive additive into a solution of a polymer binder and uniformly dispersing the materials. The main function of the adhesive is to form a framework, so that the active substance, the conductive agent and the current collector are adhered, slurry is formed in the production process to facilitate coating, and the volume change of the positive and negative electrodes during lithium extraction is relieved.
The adhesive widely used in the existing lithium ion battery is polyvinylidene fluoride Polymer (PVDF) and sodium carboxymethylcellulose plus styrene butadiene rubber (CMC + SBR), wherein the former is matched with N-methyl pyrrolidone (NMP) to form an oily system, and the latter is used as a solvent to form a water-based system. PVDF is widely used because of its stable electrochemical properties and strong adhesive properties. But PVDF is easy to swell in organic electrolyte, so that the stability and the dispersion performance of electrode slurry are easily caused, and meanwhile, the adhesive force of the electrode plate after being soaked is reduced, and a conductive network is damaged, so that the cycle performance of the battery is reduced; meanwhile, the introduction of the element F is easy to form HF in the battery, and a lot of adverse effects are brought to the battery; and the PVDF is difficult to recycle and treat in the battery recycling and treating process, and the PVDF is expensive in selling price, so that the production cost of the lithium ion battery is increased.
The existing research shows that the stability and the dispersion uniformity of the electrode slurry can directly influence the quality of the battery anode, and the specific expression is as follows: the unstable rheological property of the slurry can cause uneven distribution of the surface density of the prepared electrode or defects in local areas, the uneven distribution of the surface density of the electrode can seriously affect the consistency of the battery, and the defects in the local areas can accelerate the aging speed of the electrode; non-uniform dispersion of the active material and the conductive agent in the slurry may result in insufficient performance of the electrochemically active material in the electrode. Therefore, the rheological stability and the dispersion uniformity of the slurry are improved, and the method has very important significance for improving the performance of the battery.
There are a number of understandings in the art regarding the stability of slurries, and in general, stability refers to the ability of a dispersion to withstand mass or phase separation and to continue to maintain a uniformly dispersed state of particles for a prolonged period of time after dispersion. Phase separation can be attributed to settling, agglomeration, or ostwald ripening. For colloidal electrode slurries, the main problem is the settling of larger active material particles, or the agglomeration of less active and inactive (e.g., conductive agent) species. The repulsive force or attractive force between the particles is used for manufacturing a three-dimensional interaction net-shaped structure, so that the agglomeration and sedimentation can be effectively slowed down or prevented, and the stability of the slurry is further improved.
Furthermore, with the increasing demand for energy density of lithium ion batteries, high-specific-capacity high-nickel ternary and lithium-rich manganese-based cathode materials are being developed and used continuously. These positive electrode materials inevitably remain and form LiOH and Li during the production and storage2CO3Impurities cause the total alkali content of the anode material to be higher, so that the side reactions of the electrode in the charging and discharging process are increased, the gas expansion phenomenon is easy to occur in the charging and discharging process of the battery, and the electrochemical performance of the material is reduced to a certain extent. However, it is desirable to completely remove LiOH or Li from the surface of the material during the preparation and storage of the material2CO3There are great difficulties.
Therefore, for the positive electrode material of the lithium ion battery, how to ensure the rheological stability and the dispersion uniformity of the electrode slurry and how to inhibit the interface side reaction of the positive electrode material so as to improve the gas expansion phenomenon of the battery in the charging and discharging processes has very important significance for improving the performance of the battery.
Disclosure of Invention
Therefore, the present invention is directed to provide an electrode paste composition for suppressing interfacial side reactions of a positive electrode material, so as to solve the problem of unstable battery performance in the prior art.
In order to solve the technical problems, the electrode slurry composition for inhibiting the interfacial side reaction of the cathode material comprises the following components in percentage by total weight of the composition:
Figure BDA0001188550910000031
the additive comprises an average molecular mass (M)w) Polyacrylic acid in the range of 100g/mol to 10000 g/mol.
Preferably, the electrode slurry composition for inhibiting the interfacial side reaction of the cathode material comprises the following components in percentage by weight of the total composition:
Figure BDA0001188550910000032
more preferably, the polyacrylic acid has an average molecular mass (M)w) Is 1000g/mol to 9000 g/mol.
In the slurry composition for suppressing interfacial side reactions of a positive electrode material according to the present invention, the additive further includes an average molecular mass (M)w) Is 100g/mol to 10000g/mol of polyacrylate. Such as lithium Polyacrylate (PAALi), sodium polyacrylate (PAANa), or small molecule polymer such as polyvinyl alcohol (PVA), or small molecule substance such as oxalic acid, acetic acid, etc.
In the slurry composition for inhibiting the interface side reaction of the positive electrode material, the positive electrode active material comprises one or a mixture of more of lithium-containing metal oxides LMO, LCO, LMNO, Li-NCA, Li-NCM and lithium-rich manganese-based materials.
Specifically, the positive electrode active material includes the following materials expressed by the formula: liaA1-bBbD2(0.9≤a≤1，0≤b≤0.5)，LiaE1-bBbO2-cDc(0.9≤a≤1，0≤b≤0.5，0≤c≤0.05)，LiE2-bBbO4-cDc(0≤b≤0.5，0≤c≤0.05)，LiaNi1-b-cCobBcDα(0.9≤a≤1，0≤b≤0.5，0≤c≤0.05，0≤α≤2)，LiaNi1-b- cCobBcO2-αFα(0.9≤a≤1，0≤b≤0.5，0≤c≤0.05，0≤α≤2)，LiaNi1-b-cCobBcO2-αF2(0.9≤a≤1，0≤b≤0.5，0≤c≤0.05，0≤α≤2)，LiaNi1-b-cMnbBcO2-αFα(0.9≤a≤1，0≤b≤0.5，0≤c≤0.05，0≤α≤2)，LiaNi1-b-cMnbBcO2-αFα(0.9≤a≤1，0≤b≤0.5，0≤c≤0.05，0≤α≤2)，LiaNibEcGdO2(0.9≤a≤1，0≤b≤0.9，0≤c≤0.5，0.001≤d≤0.1)，LiaNibCocMndGeO2(0.9≤a≤1，0≤b≤0.9，0≤c≤0.5，0≤d≤0.5，0.001≤d≤0.1)，LiaNiGbO2(0.9≤a≤1，0.001≤b≤0.1)，LiaCoGbO2(0.9≤a≤1，0.001≤b≤0.1)，LiaMnGbO2(0.9≤a≤1，0.001≤b≤0.1)，LiaMn2GbO4(0.9≤a≤1，0.001≤b≤0.1)；QO2，QS2，LiQS2，V2O5，Li V2O5，LiIO2，LiNiVO4And Li(3-f)J2(PO4)3(f is more than or equal to 0 and less than or equal to 2). Wherein, the letters A, B, D, E, F, G, Q, I and J respectively represent one or more elements, and concretely: letter A represents nickel (Ni), cobalt (Co), manganese (Mn) or any combination of the three, letter B represents nickel (Ni), cobalt (Co), manganese (Mn), aluminum (Al), chromium (Cr), iron (Fe), magnesium (Mg), strontium (Sr), vanadium (V) and rare earth metal elements or any combination of the three, letter D represents oxygen (O), fluorine (F) and sulfur (S), phosphorus (P) or any combination thereof, the letter E represents cobalt (Co), manganese (Mn) or any combination thereof, the letter F represents fluorine (F), sulfur (S), phosphorus (P) or any combination thereof, the letter G represents aluminum (Al), chromium (Cr), manganese (Mn), iron (Fe), magnesium (Mg), lanthanum (La), cerium (Ce), strontium (Sr), vanadium (V) or any combination thereof, and the letter Q represents titanium (Ti), molybdenum (Mo) or any combination thereof.The letter I represents chromium (Cr), vanadium (V), iron (Fe), scandium (Sc), yttrium (Y), or any combination thereof, and the letter (J) represents vanadium (V), chromium (Cr), manganese (Mn), cobalt (Co), nickel (Ni), copper (Cu), or any combination thereof.
In the slurry composition for suppressing the interfacial side reaction of the positive electrode material according to the present invention, the positive electrode active material may be the positive electrode active material having a coating layer on the surface thereof.
In the slurry composition for inhibiting the interfacial side reaction of the cathode material, the binder is polyvinylidene fluoride (PVDF) and/or a polyimide copolymer. The polyvinylidene fluoride binder further contains a copolymer of polyvinylidene fluoride such as polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), polyvinylidene fluoride-tetrafluoroethylene-propylene (PVDF-TFE-P), or the like in addition to polyvinylidene fluoride; the copolymer of polyimide includes Polyimide (PI), Polyamideimide (PAI), Polyetherimide (PEI), and the like.
In the slurry composition for suppressing interfacial side reactions of a positive electrode material of the present invention, the average molecular weight (M) of the binder polymerw) More than 100000g/mol and less than 3000000 g/mol. When the average molecular weight of the binder polymer molecules is small, the binding force of the electrode is poor; when the average molecular weight of the polymer molecules of the binder is too large, the polymer becomes less likely to be dissolved and dispersed. The molecular weight of the binder polymer should be distributed within a reasonable range, and the average molecular weight distribution of the binder polymer molecules generally used is between 300000g/mol and 1500000 g/mol.
In the slurry composition for suppressing the interfacial side reaction of the positive electrode material of the present invention, a conductive agent material is optionally contained. The conductive agent material can provide conductive channels among the positive active material particles, and the electronic conductivity of the electrode is improved. The conductive additive material comprises carbonaceous materials, such as granular carbon black, acetylene black, ketjen black and the like, flaky or spherical graphite materials, linear carbon fiber materials, carbon nanotube materials and the like; the conductive additive further comprises a metal-based material such as a metal powder or a metal fiber material formed of copper, nickel, aluminum, silver, or the like; the conductive agent may further include a conductive polymer-based material.
The invention also provides an electrode slurry for inhibiting the interface side reaction of the cathode material, which comprises an organic solvent and the electrode slurry composition.
Preferably, the electrode slurry composition solids comprise 20 to 85wt% of the mass of the slurry.
More preferably, the viscosity of the slurry is 2000-10000 mPas.
The solvent is one or more of organic solvents N-methylpyrrolidone (NMP), N, N-dimethyl amide (DMF) and acetone.
The invention also provides a preparation method of the slurry for inhibiting the interface side reaction of the cathode material, which comprises the steps of mixing the cathode active material, the binder, the conductive agent and the additive according to the selected content, and adding the selected amount of the organic solvent to prepare the slurry.
The invention also provides application of the slurry for inhibiting the interface side reaction of the cathode material in preparing a battery electrode.
The invention also provides an electrode, which is prepared from the slurry for inhibiting the interface side reaction of the cathode material according to a conventional method, and has the effect of inhibiting the interface side reaction of the cathode material.
In the electrode, the thickness of a coating formed by the slurry is 20-300 mu m.
The invention also provides a method for preparing the electrode for inhibiting the interface side reaction of the cathode material, which comprises the following steps:
(1) uniformly mixing a positive active material, a binder, a conductive agent and an additive according to a certain proportion, and adding a certain amount of solvent to prepare slurry;
(2) the prepared slurry is coated or calendered onto a conductive current collector and sufficiently dried.
The current collector is a conductive substrate that does not undergo chemical/electrochemical reactions in the battery, and is typically a copper foil, an aluminum foil, a stainless steel sheet, a nickel sheet, a titanium sheet, or a hot-pressed carbon sheet, etc.
The drying process is divided into a solvent removal drying process and a water removal drying process, wherein the solvent removal drying process is generally carried out in an open environment, and the drying temperature is usually 50-300 ℃. The dewatering and drying process is usually carried out under vacuum or under the protection of inert gas, and the drying temperature is usually in the range of 30-150 ℃.
Of course, the lithium ion battery positive electrode can also be prepared by other methods known to those skilled in the art besides the above-mentioned methods.
The invention also provides the application of the electrode in preparing a lithium ion battery.
The invention also provides a lithium ion battery which comprises a positive electrode, a negative electrode, a diaphragm and an electrolyte, wherein the positive electrode is the electrode.
In the lithium ion battery of the present invention, the negative electrode contains an inorganic nonmetal, metal, alloy, oxide-based material having lithium intercalation/deintercalation activity, such as a graphite-based negative electrode, a silicon-based negative electrode, a tin-based negative electrode, a metal oxide negative electrode, and the like.
In the lithium ion battery, the diaphragm is an electronic insulation material with low transmission impedance to lithium ions in the electrolyte and good absorption and wettability to the electrolyte. The diaphragm material can be at least one of glass fiber, polyester fiber, polytetrafluoroethylene, polyethylene, polypropylene, polyimide and aramid fiber material. The pore size of the membrane is generally distributed between 0.1 μm and 10 μm, and the thickness is generally distributed between 5 μm and 300. mu.m.
In the lithium ion battery of the present invention, the electrolyte includes a nonaqueous electrolyte and a lithium salt, wherein the nonaqueous electrolyte may be a nonaqueous electrolyte solution, an organic solid electrolyte, or an inorganic solid electrolyte.
The electrode slurry composition is prepared by adding PAA (poly (acrylic acid)) to modify polyacrylic acid molecules with small molecular weight (-CH) on the basis of the traditional slurry composition2-) group can be compatible with the surface of the positive electrode active material and the surface of the carbonaceous conductive agent by utilizing (-COO)-) The repulsion between the groups can slow down the sedimentation and agglomeration of particles in the slurry; meanwhile, polyacrylic acid (PAA) can play a role of a certain dispersing additive, and the content of the polyacrylic acid is improvedThe dispersion uniformity of the carbon-based conductive agent and the electrochemical active material can improve the stability of the slurry and the dispersion uniformity of the carbonaceous conductive agent.
In addition, in the positive electrode slurry containing lithium-containing metal oxides LMO, LCO, LMNO, Li-NCA, Li-NCM, lithium-rich manganese-based materials, etc. as electrochemical active materials, acidic carboxyl (-COOH) groups in PAA molecules can neutralize LiOH and/or Li in the positive electrode active materials2CO3And the alkaline substances can inhibit the interface side reaction of the positive electrode material to a certain extent, improve the electrochemical performance of the positive electrode active material and inhibit or reduce gas generation to a certain extent.
In the electrode for inhibiting the interface side reaction of the cathode material, polyacrylic acid (PAA) has certain corrosivity on a current collector, and the adhesive force between an electrode coating and the current collector can be improved.
In the electrode slurry composition of the present invention, the PAA may be dissolved in a conventional NMP solvent and may stably coexist with PVDF. Experiments have shown that for the selection of the polyacrylic acid according to the invention, the average molecular mass (M) of the polyacrylic acid additive isw) Less than 10000g/mol, it is distributed on the surface of active material and/or conductive agent particle, mainly acts as additive; when the average molecular mass (M) of the polyacrylic acid additivew) When the content is more than 10000g/mol, the active material can be connected with the current collector, and the active material and the current collector can further play a role of a binder. Therefore, the selection of PAA having the appropriate molecular weight is effective in suppressing the side reaction of the positive electrode material.
In the slurry composition for inhibiting the interface side reaction of the cathode material, the mass fraction of the PVDF binder in the total amount of the electrode slurry composition is 0.5-15 wt%. Within the range, the binder can play a good role in binding among active material particles, between the active material particles and conductive agent particles, and between the electrode coating and the current collector, so that the stability and the dispersibility of the whole slurry are effectively improved.
Detailed Description
Example 1
Polyvinylidene fluoride (PVDF) having an average molecular weight (Mw) of about 800000g/mol was dissolved in N-methyl-pyrrolidone (NMP) solvent to prepare a solution having a mass fraction of 6 wt%. Polyacrylic acid (PAA) having an average molecular weight (Mw) of about 2000g/mol was dissolved in N-methyl-pyrrolidone (NMP) to prepare a solution having a mass fraction of 20 wt%.
With Li [ Ni ]0.8Co0.1Al0.1]O2As positive electrode active material, conductive carbon black Super-P and conductive graphite Ks-6 as conductive agent, according to Li [ Ni ]0.8Co0.1Al0.1]O2: Super-P: ks-6: PVDF: PAA 93: 2: 1: 4: 0.1, adding a proper amount of NMP, and fully and uniformly stirring to prepare slurry with the solid content of 40-60% and the viscosity of 4000-6000mPa ∙ s.
And (3) taking a small amount of slurry, putting the slurry into a 100mL measuring cylinder, standing at room temperature, and recording the time of solid-liquid phase separation of the slurry.
The prepared slurry was uniformly coated on an aluminum foil having a thickness of 15 μm, and the amount of solid matter supported per unit area in the electrode coating was controlled to be 20mg/cm2And dried sufficiently in an open environment to remove the NMP solvent from the electrode.
Graphite material 360MB (produced by Shenzhen fibrate Rayleigh corporation) is used as a negative active material, conductive carbon black Super-P is used as a conductive agent, CMC and SBR are used as a binder, and the ratio of the conductive carbon black Super-P to the conductive carbon black Super-P is determined according to the following steps of 360 MB: Super-P: CMC: SBR in a ratio of 96:1.5:1:1.5 was prepared as an aqueous slurry. Coating the prepared slurry on a copper foil with the thickness of 10 mu m, and controlling the loading amount of solid matters in the electrode coating to be 12mg/cm2And drying in open environment to remove H in the electrode2And (4) O solvent.
And (3) drying the prepared positive and negative electrodes at 80 ℃ in vacuum for 12h, and removing water in the electrodes. And assembling the dehydrated and dried positive and negative electrodes into a 2Ah soft package battery, and recording the volume of the generated gas of the battery at normal temperature and normal pressure in the activation stage of the battery. The activated battery is in a voltage range of 2.8-4.2V, and the cycling stability of the battery is tested by using the multiplying power of 1C.
Comparative example 1
Comparison of booksThe slurry, electrode and lithium ion battery for suppressing the interfacial side reaction of the positive electrode material described in the example are the same as in example 1, except that Li [ Ni ] is used in the same manner0.8Co0.1Al0.1]O2: Super-P: ks-6: PVDF 93: 2: 1: 4 to prepare slurry.
And (3) taking a small amount of slurry, putting the slurry into a 100mL measuring cylinder, standing at room temperature, recording the time of solid-liquid phase separation of the slurry, and recording the performance of the prepared battery.
Example 2
Polyvinylidene fluoride (PVDF) having an average molecular weight (Mw) of about 1300000g/mol was dissolved in N-methyl-pyrrolidone (NMP) to prepare a solution having a mass fraction of 5 wt%. Polyacrylic acid (PAA) having an average molecular weight (Mw) of about 2000g/mol was dissolved in N-methyl-pyrrolidone (NMP) to prepare a solution having a mass fraction of 20 wt%. With Li [ Ni ] as Li-rich manganese-based material0.167Li0.2Co0.167Mn0.553]O2As positive electrode active material, conductive carbon black Super-P and conductive graphite Ks-6 as conductive agent, according to Li [ Ni ]0.167Li0.2Co0.167Mn0.553]O2: Super-P: ks-6: PVDF: PAA 92: 3: 2: 3: 0.1, adding a proper amount of NMP, and fully and uniformly stirring to prepare the slurry with the solid content of 40-60% and the viscosity of 4000-6000mPa ∙ s.
And (3) taking a small amount of slurry, putting the small amount of slurry into a 100mL measuring cylinder, standing the slurry at room temperature, and recording the time of solid-liquid phase separation of the two groups of slurry.
The prepared slurry was uniformly coated on an aluminum foil having a thickness of 20 μm, and the amount of solid matter supported per unit area in the electrode coating was controlled to be 16mg/cm2And dried sufficiently in an open environment to remove the NMP solvent from the electrode.
Graphite material 360MB (produced by Shenzhen fibrate Rayleigh corporation) is used as a negative active material, conductive carbon black Super-P is used as a conductive agent, CMC and SBR are used as a binder, and the ratio of the conductive carbon black Super-P to the conductive carbon black Super-P is determined according to the following steps of 360 MB: Super-P: CMC: SBR in a ratio of 96:1.5:1:1.5 was prepared as an aqueous slurry. Coating the prepared slurry on a copper foil with a thickness of 10 μm, and controlling the electrodesThe loading of solid matter in the coating per unit area was 12mg/cm2And drying in open environment to remove H in the electrode2And (4) O solvent.
And (3) drying the prepared positive and negative electrodes at 80 ℃ in vacuum for 12h, and removing water in the electrodes. And assembling the dehydrated and dried positive and negative electrodes into a 2Ah soft package battery, and recording the volume of the generated gas of the battery at normal temperature and normal pressure in the activation stage of the battery. The activated battery is tested for the cycling stability of the battery in a voltage range of 2.0-4.6V with a rate of 0.3C.
Comparative example 2
The slurry, electrode and lithium ion battery for suppressing the interfacial side reaction of the positive electrode material according to this comparative example were the same as those of example 2 except that Li [ Ni ] was used in the same manner0.167Li0.2Co0.167Mn0.553]O2: Super-P: ks-6: PVDF 92: 3: 2: 3 to prepare slurry.
And (3) taking a small amount of slurry, putting the slurry into a 100mL measuring cylinder, standing at room temperature, recording the time of solid-liquid phase separation of the slurry, and recording the performance of the prepared battery.
Example 3
The composition of the slurry for inhibiting the interfacial side reaction of the cathode material in the embodiment comprises the following components in percentage by total weight of the composition:
positive electrode active material (Li [ Ni ]0.8Co0.1Al0.1]O2)50wt％；
15wt% binder (PVDF);
additive (PAA, M)w1000g/mol)0.01wt％；
34.99 wt% of conductive agent (Super-P: Ks-6).
The preparation of the slurry and the preparation of the electrode and lithium ion battery were the same as in example 1.
Example 4
The composition of the slurry for inhibiting the interfacial side reaction of the cathode material in the embodiment comprises the following components in percentage by total weight of the composition:
positive electrode active material (Li [ Ni ]0.8Co0.1Al0.1]O2)99wt％；
0.5 wt% of a binder (PVDF);
additive (PAA, M)w1000g/mol)0.5wt％。
The preparation of the slurry and the preparation of the electrode and lithium ion battery were the same as in example 1.
Example 5
The composition of the slurry for inhibiting the interfacial side reaction of the cathode material in the embodiment comprises the following components in percentage by total weight of the composition:
positive electrode active material (Li [ Ni ]0.8Co0.1Al0.1]O2) 80wt％；
10wt% of binder (PVDF);
additive (PAA, M)w1000g/mol) 0.1wt％；
9.9 wt% of conductive agent (Super-P: Ks-6).
The preparation of the slurry and the preparation of the electrode and lithium ion battery were the same as in example 1.
Example 6
The composition of the slurry for inhibiting the interfacial side reaction of the cathode material in the embodiment comprises the following components in percentage by total weight of the composition:
positive electrode active material (Li [ Ni ]0.8Co0.1Al0.1]O2) 96wt％；
1wt% of a binder (PVDF);
additive (PAA, M)w1000g/mol) 1wt％；
2 wt% of conductive agent (Super-P: Ks-6).
The preparation of the slurry and the preparation of the electrode and lithium ion battery were the same as in example 1.
Examples of the experiments
The properties of the slurries prepared in the above examples 1-2 and comparative examples 1-2 and the properties of the batteries prepared therefrom were measured according to the conventional methods, and the properties of the measurements are reported in table 1.
TABLE 1. related Properties of the slurries of the present invention and the lithium ion batteries
Figure BDA0001188550910000121
As can be seen from the data in the above table, the slurry composition of the present invention effectively improves the rheological stability and the dispersion uniformity of the electrode slurry by utilizing the interaction of PAA with the existing binder, and has a longer phase separation time compared with the conventional slurry using PVDF as the binder only; the slurry can effectively inhibit the side reaction of the interface of the anode material, effectively reduce the gas production of the lithium ion battery and effectively improve the cycle efficiency of the battery.
It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.

Claims (9)

1. An electrode slurry for inhibiting interfacial side reactions of a cathode material, comprising an organic solvent and an electrode slurry composition, wherein the electrode slurry composition comprises the following components in terms of the total amount of the electrode slurry composition:
50-99wt% of positive electrode active material;
0.5-15wt% of binder;
0.01-3wt% of additive;
0-35wt% of conductive agent;
the electrode slurry composition accounts for 20-85wt% of the mass of the slurry;
the additive comprises an average molecular mass (M)w) Polyacrylic acid of 100g/mol to 10000g/mol and average molecular mass (M)w) Polyacrylate in an amount of 100g/mol to 10000 g/mol;
the positive electrode active material includes a lithium-containing metal oxide Li-NCA and/or Li-NCM;
the binder is polyvinylidene fluoride (PVDF) and/or polyimide copolymer;
average molecular weight (M) of the polymer of the binderw) More than 100000g/mol and less than 3000000 g/mol;
the conductive agent comprises carbon black, flake or spherical graphite materials, linear carbon fiber materials or carbon nanotubes;
the organic solvent comprises one or more of N-methylpyrrolidone (NMP), N, N-dimethyl amide (DMF) and acetone.
2. The electrode slurry for suppressing interfacial side reactions of a positive electrode material according to claim 1, wherein the carbon black is acetylene black or ketjen black.
3. The electrode slurry for suppressing the interfacial side reaction of the positive electrode material according to claim 1, wherein a metal-based material and/or a conductive polymer is added to the conductive agent.
4. The electrode slurry for suppressing the interfacial side reaction of a positive electrode material according to claim 1, wherein the electrode slurry composition comprises the following components, in terms of the total amount thereof:
80-96wt% of positive electrode active material;
1-10wt% of a binder;
0.1-1wt% of additive;
the balance of the conductive agent.
5. Use of the electrode slurry for suppressing interfacial side reactions of a positive electrode material according to any one of claims 1 to 4 for producing a battery electrode.
6. An electrode, characterized in that, the electrode slurry for inhibiting the interface side reaction of the cathode material according to any one of claims 1 to 4 is prepared according to the conventional method.
7. The electrode of claim 6, wherein the slurry forms a coating having a thickness of 20-300 μm.
8. Use of the electrode of claim 6 or 7 for the preparation of a lithium ion battery.
9. A lithium ion battery comprising a positive electrode, a negative electrode, a separator and an electrolyte, wherein the positive electrode is the electrode of claim 6 or 7.
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