Non-aqueous electrode sheet and preparation method thereof

Abstract

The present invention relates to the field of battery technology, and in particular to a non-aqueous electrode plate and a preparation method thereof, comprising the following steps: melting and dissolving PVDF powder and a solvent at a temperature of X°C to Y°C to obtain a PVDF solution; the melting point of PVDF being <X°C <Y°C <316°C; stirring and mixing an electrode active material, conductive carbon black, and a conductive agent slurry at room temperature to Y°C to obtain a mixed slurry; stirring and mixing the PVDF solution and the mixed slurry at room temperature to Y°C to obtain an electrode slurry; and controlling the discharge temperature of the electrode slurry between room temperature and 316°C for coating. The preparation method utilizes high-temperature PVDF pre-dissolution technology, with the stirring temperature controlled above the PVDF melting point, to rapidly dissolve the PVDF particles in the solvent and promote molecular chain stretching, thereby producing a high-solids, fully dissolved PVDF solution.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a non-aqueous electrode plate and a preparation method thereof. Background Art

[0002] Currently, commercial cathode material slurrying mostly uses NMP (N-methylpyrrolidone) as a solvent to disperse or dissolve the various components. NMP's main function is to dissolve the binder and adjust the viscosity of the slurry. It has the characteristics of being easy to dry and non-toxic. The amount of NMP used depends on the solubility of the binder PVDF (polyvinylidene fluoride) and the slurry viscosity (appropriate viscosity is required for coating). Existing slurrying processes generally use room temperature PVDF pre-dissolution or dry processes. These processes have problems such as the high NMP content in the battery cell cost (accounting for 30%-60% of the total slurry weight and about 6% of the battery cell cost), the long time it takes for NMP to fully dissolve, and the high energy consumption of NMP drying (the drying process of the cathode coating accounts for 50% of the energy consumption of the production line). The high cost of NMP and the huge energy consumption of drying contribute to the high cost of the battery cell. The long time it takes for NMP to fully dissolve will lead to reduced process production efficiency and increased investment in stirring equipment.

[0003] CN316010764356.8 discloses a high-temperature, low-energy consumption positive electrode slurry process, which controls the kneading and dispersion temperatures at 40°C-70°C to accelerate the dissolution of PVDF and reduce the amount of circulating cooling water used to achieve the purpose of improving process efficiency and reducing process energy consumption. However, the high temperature of 40°C-70°C has little effect on the dissolution rate of PVDF. In the ordinary dispersion process, the slurry temperature can basically exceed 40°C due to the frictional heat generated by the dispersion disk. Due to the upper temperature limit of 70°C, this technology cannot adopt long-term high-intensity dispersion operations. Therefore, the process is designed with 4 dispersion actions, during which a slow stirring step is added, which prolongs the process time and reduces the process production efficiency. The amount of NMP dissolution has not been significantly reduced. Summary of the Invention

[0004] The present invention provides a non-aqueous electrode plate and its preparation method, addressing the shortcomings of existing electrode material preparation methods, such as low PVDF dissolution efficiency and high solvent usage. High-temperature PVDF pre-dissolution technology is employed to achieve efficient PVDF dissolution, reduce solvent usage, and increase PVDF dissolution speed. High-temperature slurry mixing reduces PVDF precipitation. The inert atmosphere during pre-dissolution and secondary stirring minimizes the reaction between PVDF and airborne water at high temperatures, weakening the cross-linking reaction of PVDF at high temperatures. The high-temperature slurry discharge and coating process reduces electrode plate drying time and energy consumption.

[0005] In a first aspect, the present invention provides a method for preparing a non-aqueous electrode sheet, comprising the following steps:

[0006] Melting and dissolving PVDF powder and a solvent at X°C-Y°C to obtain a PVDF solution; wherein the melting point of the PVDF is less than X°C and less than Y°C and less than 316°C;

[0007] The electrode active material, conductive carbon black and conductive agent slurry are stirred and mixed uniformly for the first time at room temperature -Y°C to obtain a mixed slurry;

[0008] The obtained PVDF solution and the mixed slurry are stirred and mixed uniformly for a second time at room temperature-Y°C to obtain an electrode slurry;

[0009] The discharge temperature of the electrode slurry is controlled to be between room temperature and 316° C. for coating.

[0010] Furthermore, the electrode active material, the conductive carbon black and the conductive agent slurry are stirred and mixed uniformly for the first time at X°C-Y°C to obtain a mixed slurry.

[0011] Furthermore, the obtained PVDF solution and the mixed slurry are stirred and mixed uniformly for a second time within the range of X°C-Y°C to obtain electrode slurry.

[0012] Furthermore, the discharge temperature of the electrode slurry is controlled to be between X°C and 316°C for coating.

[0013] Furthermore, the boiling point of the solvent is lower than the cracking temperature of the PVDF.

[0014] Furthermore, when the boiling point of the solvent is greater than the melting point of the PVDF, the Y°C is less than or equal to (the boiling point of the solvent - 5°C).

[0015] Furthermore, when the boiling point of the solvent is less than or equal to the melting point of the PVDF, the melt dissolution and the second stirring are also carried out under pressure P to keep the solvent in a liquid state; the pressure P is the saturated vapor pressure of the solvent at the stirring temperature*(1.1-1.5).

[0016] Furthermore, the solid content of the PVDF solution is 20%-90%.

[0017] Furthermore, the melt dissolution and the second stirring are performed under an inert atmosphere.

[0018] In a second aspect, the present invention further provides a non-aqueous electrode plate, which is prepared using the above-mentioned preparation method.

[0019] The present invention provides a method for preparing a non-aqueous electrode material using high-temperature PVDF pre-dissolution technology. During stirring, the temperature is controlled above the PVDF melting point, rapidly dissolving the PVDF particles in the solvent and promoting molecular chain stretching, resulting in a high-solids (low-NMP) and fully dissolved PVDF solution. The solvent primarily serves as a dispersant, reducing solvent usage and expanding the range of solvent options.

[0020] The present invention further performs a first stirring and mixing of the electrode active material, conductive carbon black and conductive agent slurry to obtain a mixed slurry at a temperature of X°C-Y°C. High-temperature stirring can accelerate the mixing between particles, shorten the dispersion time, improve the dispersion efficiency, reduce the use of cooling water and reduce energy consumption, and avoid the problem of PVDF precipitation caused by the "condensation" of the PVDF solution due to the mixing of the two phases added during the subsequent second stirring. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 This is one of the flow diagrams of a method for preparing a non-aqueous electrode sheet provided by the present invention;

[0023] Figure 2 This is a coating interface diagram of the electrode plate obtained in Example 1 of the present invention. DETAILED DESCRIPTION

[0024] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0025] According to the first aspect of the present invention, the present invention provides a method for preparing a non-aqueous electrode sheet, the process flow chart of the preparation method is as follows: Figure 1 As shown, the preparation method specifically comprises the following steps:

[0026] PVDF powder and a solvent are melted and dissolved at X°C-Y°C to obtain a PVDF solution; wherein the melting point of the PVDF is <X°C <Y°C <316°C.

[0027] The electrode active material, conductive carbon black and conductive agent slurry are stirred and mixed uniformly for the first time at room temperature -Y°C to obtain a mixed slurry.

[0028] The obtained PVDF solution and the mixed slurry were stirred and mixed uniformly for the second time at room temperature -Y°C to obtain electrode slurry.

[0029] The discharge temperature of the obtained electrode slurry was controlled at room temperature -316°C for coating.

[0030] It should be noted that normal temperature generally refers to a temperature between 20°C and 30°C. The melting point of PVDF varies depending on the molecular weight, but is generally between 160°C and 175°C. The conductive agent slurry is selected from a carbon nanotube slurry or a graphene slurry.

[0031] In the above scheme, PVDF is pre-dissolved before being added to the slurry. Pre-dissolution is to mix PVDF powder with a solvent that can dissolve PVDF. The temperature of the melt dissolution is controlled above the melting point of PVDF, so that PVDF is mixed with the solvent in a molten state. This can quickly and fully achieve the dissolution of PVDF in the solvent, and is conducive to the stretching of the PVDF molecular chain in a short time, reducing the stirring time. The solvent mainly plays a dispersing role, which can reduce the amount of solvent used and expand the range of solvent selection. It can be understood that 316℃ is the cracking temperature of PVDF. Limiting Y℃ to less than 316℃ is conducive to expanding the range of solvent selection.

[0032] The following is a detailed description of this program:

[0033] In a feasible embodiment, the electrode active material, the conductive carbon black and the conductive agent slurry are stirred and mixed uniformly for the first time at X°C-Y°C to obtain a mixed slurry.

[0034] In the present invention, the temperature used in the process of first stirring and mixing the electrode active material, conductive carbon black and conductive agent slurry to obtain the mixed slurry is under the condition of X℃-Y℃. High-temperature stirring can accelerate the mixing between the particles and avoid the problem of PVDF precipitation caused by "condensation" of the PVDF solution in the subsequent two-phase mixing.

[0035] In a feasible embodiment, the obtained PVDF solution and the mixed slurry are stirred and mixed uniformly for a second time within the range of X°C-Y°C to obtain electrode slurry.

[0036] It can be understood that in the present invention, the obtained PVDF solution and mixed slurry are stirred and mixed for the second time at X℃-Y℃ to obtain electrode slurry. High-temperature dispersion can withstand higher intensity dispersion shear force, which is beneficial to improving dispersion efficiency and avoiding premature precipitation of PVDF in the slurry.

[0037] In a feasible embodiment, the discharge temperature of the electrode slurry is controlled to be between X°C and 316°C for coating.

[0038] The present invention coats the obtained electrode slurry at a temperature of X°C to 316°C. The high temperature can maintain the low viscosity of the slurry, improve the fluidity of the slurry, and be beneficial to achieving consistency in coating thickness, thereby improving coating efficiency and quality. High-temperature discharge is also beneficial to drying the solvent, reducing the drying time of the electrode in the oven, reducing drying energy consumption, and saving investment in drying equipment such as ovens.

[0039] In a feasible embodiment, the boiling point of the solvent is lower than the cracking temperature of the PVDF.

[0040] In a feasible embodiment, the solvent is selected from one or more of NMP, DMSO, DMAC, DMF, acetone, glycerol, ethyl acetate, ether, ethylene glycol ether, triethanolamine, etc. The above are only examples and are not limiting.

[0041] NMP, with the chemical formula C₅H₄NO₂, is a colorless to pale yellow, transparent liquid with a slight ammoniacal odor. It is miscible with water in all proportions and soluble in ether, acetone, esters, halogenated hydrocarbons, aromatic hydrocarbons, and other organic solvents. It is completely miscible with almost all solvents and dissolves most organic and inorganic compounds, polar gases, and natural and synthetic polymers. NMP has a boiling point of 202°C. DMSO (dimethyl sulfoxide) is a sulfur-containing organic compound with the molecular formula C₂H₆OS. It is a colorless, odorless, transparent liquid at room temperature and is hygroscopic and flammable. It has high polarity, a high boiling point, good thermal stability, is aprotic, and is miscible with water. It is soluble in most organic compounds, including ethanol, propanol, benzene, and chloroform, earning it the nickname "universal solvent." DMSO has a boiling point of 189°C. DMAC, short for N,N-dimethylacetamide, is a commonly used aprotic polar solvent. It is a colorless, transparent, and flammable liquid. It can be mixed with organic solvents such as water, alcohol, ether, ester, benzene, chloroform and aromatic compounds. The boiling point of DMAC is 164°C. DMF, the full name of which is N,N-dimethylformamide, is an organic compound with the chemical formula C3H7NO. It is a colorless, transparent liquid. It is not only a chemical raw material with a wide range of uses, but also an excellent solvent with a wide range of uses. It can be mixed with water and most organic solvents except halogenated hydrocarbons, and has good solubility for a variety of organic and inorganic compounds. The boiling point of DMF is 153°C. In some specific embodiments, selecting DMSO as a solvent can reduce the drying energy consumption by more than 50%, and selecting DMF instead of NMP can reduce the electrode drying energy consumption by 4 times.

[0042] It is understandable that the existing solution for dissolving PVDF is generally carried out at room temperature, so there are relatively few solvents that can dissolve PVDF at room temperature. The present invention melts and dissolves PVDF under high temperature conditions, and the solvent only acts as a diluent. The range of choice of the corresponding solvent is wider. The solvent can achieve the dissolution of PVDF or it can be insoluble and only play a dispersing role. At this time, PVDF is a suspension. The solvent can be selected from one or more of NMP, DMSO, DMAC, DMF, acetone, glycerol, ethyl acetate, ether, ethylene glycol ether, triethanolamine, etc. As a single solvent, a variety of solvents can also be used to mix to form a mixed solvent. By making a reasonable choice of the type of solvent, PVDF can be fully and effectively dissolved in the pre-dissolution process, so that the subsequent slurry dispersion effect and consistency are good. The above-mentioned solvent of the present invention can be fully mixed with other electrode materials by stirring at high temperature or high temperature and high pressure or at room temperature or at room temperature.

[0043] In a feasible embodiment, the Y°C is less than the boiling point of the solvent.

[0044] It can be understood that by limiting Y°C to be less than the boiling point of the solvent, it is possible to prevent the solvent from volatilizing during the dissolution of PVDF in the solvent, so that the solvent remains in a liquid state, thereby effectively dissolving PVDF.

[0045] In a feasible embodiment, when the boiling point of the solvent is greater than the melting point of PVDF, Y°C is less than (the boiling point of the solvent - 5°C). In a specific embodiment, NMP is selected as the solvent, and Y°C is less than or equal to 197°C.

[0046] It can be understood that limiting Y°C to be less than or equal to the boiling point of the solvent -5°C can more effectively keep the solvent in a liquid state, thereby more effectively achieving sufficient dissolution of PVDF in the solvent.

[0047] In a feasible embodiment, when the boiling point of the solvent is less than or equal to the melting point of the PVDF, the melt dissolution and the second stirring are also performed under a pressure P to keep the solvent in a liquid state. The pressure P is the saturated vapor pressure of the solvent at the stirring temperature * (1.1-1.5).

[0048] For example, when DMF is the solvent, its boiling point is 153°C, which is lower than its melting point of 180°C. Therefore, a pressure P must be applied to the mixing tank to maintain the DMF in a liquid state during the pre-dissolution and secondary stirring phases. This effectively prevents solvent volatilization during the melting and secondary stirring phases, thus preventing phase separation. For single solvents, the saturated vapor pressure at different temperatures can be found in reference books such as the Organic Volume of the Handbook of Chemical Properties. For non-single solvents, the saturated vapor pressure of the mixture system must be determined experimentally, typically using the three-stage expansion method.

[0049] In a feasible embodiment, the solid content of the PVDF solution is 20%-90%.

[0050] Optionally, the solid content of the PVDF solution may be 20%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85% or 90%, etc., and may also be other values ​​within the above range, which is not limited here.

[0051] It can be understood that by limiting the solid content of the PVDF solution to 20%-90%, the amount of solvent used can be significantly reduced, thereby saving solvent consumption and recycling costs, and further reducing the manufacturing cost and drying energy consumption of the electrode material.

[0052] In a feasible embodiment, the melt dissolution and the second stirring are performed under an inert atmosphere.

[0053] Alternatively, the inert atmosphere may be a gas such as argon.

[0054] It can be understood that by carrying out the melt dissolution and the second stirring under an inert atmosphere, the occurrence of side reactions can be avoided and it is also beneficial to adjust the pressure in the dissolution tank and the stirring tank.

[0055] According to a second aspect of the present invention, a non-aqueous electrode plate is provided, which is prepared using the above-mentioned preparation method and can be used as a positive electrode plate.

[0056] The following further describes the embodiments of the present application in multiple embodiments. The embodiments of the present application are not limited to the following specific embodiments. Within the scope of protection, appropriate changes can be made to the implementation.

[0057] The following examples and comparative examples use the same PVDF with a melting point of 175°C.

[0058] Example 1

[0059] A method for preparing a non-aqueous electrode sheet comprises the following steps:

[0060] PVDF powder and a solvent are melt-dissolved at 175-185° C. to obtain a PVDF solution. The solvent is selected from NMP. The melting and dissolving time is 0.5 h. The solid content of the PVDF solution is 50%.

[0061] The electrode active material, conductive carbon black and conductive agent slurry are stirred and mixed uniformly for the first time at 175-185° C. to obtain a mixed slurry.

[0062] The resulting PVDF solution and mixed slurry were stirred and mixed a second time at 175-185°C to achieve uniform dispersion and stability of the resulting electrode slurry. NMP accounted for 25% of the total electrode slurry. An argon atmosphere was used during the melt dissolution and second stirring to control the ingress of moisture from the air into the slurry.

[0063] The electrode slurry discharge temperature is adjusted to 175℃-180℃ for coating and drying. It is dried in a coating oven at 180℃. The drying time (belt running time) is shown in Table 1 below. The coating interface of the electrode sheet after drying is as follows: Figure 2 As shown. Figure 2 The results show that the obtained electrode plate particles are fully dispersed, the plate has no pitting, and the interface is flat and smooth.

[0064] Example 2

[0065] A method for preparing a non-aqueous electrode sheet comprises the following steps:

[0066] PVDF powder and a solvent are melt-dissolved at 175-185°C and pressure P to obtain a PVDF solution. The solvent is selected from DMF. Pressure P = saturated vapor pressure of DMF at 180°C * 1.2, specifically 0.34 MPa. The melting and dissolving time is 1 hour. The solids content of the PVDF solution is 90%.

[0067] The electrode active material, conductive carbon black and conductive agent slurry were stirred and mixed uniformly for the first time at 175-185° C. to obtain a mixed slurry, and the duration was 1 hour.

[0068] The resulting PVDF solution and mixed slurry were stirred and mixed for a second time at 175-185°C for 1 hour to obtain an electrode slurry. The resulting electrode slurry exhibited uniform dispersion and good stability. NMP accounted for 20% of the total electrode slurry. An argon atmosphere was used during the melt dissolution and second stirring to control the ingress of moisture from the air into the slurry.

[0069] The electrode slurry discharge temperature was adjusted to 175°C-180°C for coating and drying. The slurry was dried in a coating oven at 180°C. The drying time (conveying time) is shown in Table 1 below.

[0070] Example 3

[0071] A method for preparing a non-aqueous electrode sheet comprises the following steps:

[0072] PVDF powder and a solvent are melt-dissolved at 175-185°C to obtain a PVDF solution. The solvent is a mixed solvent of NMP and DMAC in a mass ratio of 1:1. The melt-dissolution time is 1 hour, and the solid content of the PVDF solution is 90%.

[0073] The electrode active material, conductive carbon black and conductive agent slurry were stirred and mixed uniformly for the first time at 175-185° C. for 1 hour to obtain a mixed slurry.

[0074] The obtained PVDF solution and the mixed slurry are stirred and mixed for a second time at 175-185°C to obtain an electrode slurry. The components in the obtained electrode slurry are well dispersed and stable. The mixed solvent accounts for 20% of the total amount of the electrode slurry.

[0075] The obtained electrode slurry was coated at 175° C. to 180° C. to obtain a high-temperature electrode sheet. The high-temperature electrode sheet was placed in an oven and dried at 180° C. The drying time is shown in Table 1 below.

[0076] Comparative Example 1

[0077] A method for preparing a non-aqueous electrode sheet comprises the following steps:

[0078] PVDF powder and a solvent are pre-dissolved at 70° C. to obtain a PVDF solution. The solvent is selected from NMP. The pre-dissolution time is 5 hours, and the solid content of the PVDF solution is 10%.

[0079] The electrode active material, conductive carbon black and conductive agent slurry were stirred and mixed uniformly for the first time at 70° C. for 2 h to obtain a mixed slurry.

[0080] The resulting PVDF solution and mixed slurry were stirred and mixed for a second time at 70°C for 2 hours to obtain an electrode slurry. The resulting electrode slurry exhibited good dispersion and stability. NMP accounted for 39% of the total electrode slurry.

[0081] The obtained electrode slurry was coated at 70°C to obtain an electrode sheet. The electrode sheet was placed in an oven and dried at 180°C for the drying time shown in Table 1. The particles on the coating interface of the obtained dried electrode sheet were well dispersed and the interface was flat and smooth.

[0082] Comparative Example 2

[0083] A method for preparing a non-aqueous electrode sheet comprises the following steps:

[0084] PVDF powder and a solvent are pre-dissolved at room temperature to obtain a PVDF solution. The solvent is selected from NMP. The pre-dissolution time is 10 hours. The solid content of the PVDF solution is 5%.

[0085] The electrode active material, conductive carbon black and conductive agent slurry were stirred and mixed uniformly for the first time at room temperature to obtain a mixed slurry for 2 hours.

[0086] The obtained PVDF solution and the mixed slurry were stirred and mixed for a second time at room temperature for 3 hours to obtain an electrode slurry. The components in the obtained electrode slurry were well dispersed and stable. Among them, NMP accounted for 51% of the total amount of the electrode slurry.

[0087] The obtained electrode slurry was coated at room temperature to obtain an electrode sheet. The electrode sheet was placed in an oven and dried at 180°C for the drying time shown in Table 1. The particles on the obtained dried electrode sheet were well dispersed and the interface was flat and smooth.

[0088] Comparative Example 3

[0089] A method for preparing a non-aqueous electrode sheet comprises the following steps:

[0090] PVDF powder and a solvent are pre-dissolved at 160°C to obtain a PVDF solution. The solvent is selected from NMP. The pre-dissolution time is 3.5 hours. The solid content of the PVDF solution is 15%.

[0091] The electrode active material, conductive carbon black and conductive agent slurry were stirred and mixed uniformly for the first time at room temperature to obtain a mixed slurry for 2 hours.

[0092] The resulting PVDF solution and mixed slurry were stirred and mixed for a second time at 160°C for 3 hours to obtain an electrode slurry. The resulting electrode slurry exhibited good dispersion and stability. NMP accounted for 34% of the total electrode slurry.

[0093] The obtained electrode slurry was coated at 160°C to obtain an electrode sheet. The electrode sheet was placed in an oven and dried at 180°C for the drying time shown in Table 1. The particles on the obtained dried electrode sheet were well dispersed and the interface was flat and smooth.

[0094] The electrode plates of Examples 1-5 and the comparative example after drying were subjected to adhesion test, conductivity test and battery performance test, and the test results are shown in Table 1 below.

[0095] As described above, the test method

[0096] 1. The adhesion test method is as follows:

[0097] The peel strength is tested by pulling the adhesive tape on the electrode to evaluate the bonding strength of the electrode.

[0098] ① Pole piece shearing: take the rolled pole piece and cut it into pieces with a length of 400mm and a width of 12mm;

[0099] ② Use double-sided tape to stick the electrode on the steel plate;

[0100] ③ Use a tensile test to measure the force when the electrode is peeled off, and the peeling speed is 100mm / min;

[0101] ④ Judgment standard after peeling: No empty foil should be visible after the electrode is peeled off;

[0102] ⑤The peeling angle is 180°.

[0103] 2. Conductivity test method: Use the 4-probe method to test the comprehensive resistance impedance of the electrode.

[0104] ① Punching the electrode, punching the cold pressed electrode, the diameter should be greater than 4*probe distance;

[0105] ② Test after the four probes touch the electrode, and adjust the current accuracy according to the different electrode pieces.

[0106] 3. The battery performance test method is as follows:

[0107] 3.1 Impedance test

[0108] The battery cells in this experiment were assembled into 30Ah stacked cells. The impedance was tested using 1C cells at 50% SOC, and the 1s DCR was taken as the standard.

[0109] ①Battery cell constant capacity: 0.33C charge to 3.6V, CV to 0.05C, 1C DC to 2V, cycle 3 times, 1C discharge average value is the capacity;

[0110] ② Adjust SOC: discharge at 1C for 30 minutes, adjust SOC to 50%, and let it stand at 25℃ for 2 hours;

[0111] ③ Pulse discharge: 1C discharge for 60s, with the voltage at the end of 1s being V1 and the voltage 1s before discharge being V0. DCR = (V0 - V1) / I, where I = the 1C current value.

[0112] 3.2 Cyclic test at room temperature 25℃

[0113] Cycle test of battery cells

[0114] ①Constant volume, same as 3.1.

[0115] ② Cycle to 90% SOC, charge to 3.6V at 0.33C, CV to 0.05C, and DC to 2V at 1C. After charging and discharging, let the battery rest for 1 hour until the capacity decays to 90% of the initial capacity. Calculate the number of cycles.

[0116] 4. The test method for saturated vapor pressure refers to the three-stage expansion method described in SH / T0769-2005.

[0117] Table 1 Comparative table of electrode slurries performance of Examples 1-3 and Comparative Examples 1-3

[0118]

[0119]

[0120] It can be seen from the experimental data in Table 1 that the preparation method of the present invention can effectively reduce the PVDF slurrying time, reduce the amount of solvent used, shorten the drying time of the electrode plate, and the obtained electrode plate has good bonding performance and battery performance.

[0121] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for preparing a non-aqueous electrode sheet, characterized in that: The steps include: Melting and dissolving PVDF powder and a solvent at X°C-Y°C to obtain a PVDF solution; wherein the melting point of the PVDF is less than X°C < Y°C < 316°C; and the solid content of the PVDF solution is 50%-90%; The electrode active material, conductive carbon black and conductive agent slurry are stirred and mixed uniformly for the first time at X°C-Y°C to obtain a mixed slurry; The obtained PVDF solution and the mixed slurry are stirred and mixed uniformly for a second time in the range of X°C-Y°C to obtain an electrode slurry; The discharge temperature of the electrode slurry is controlled to be between room temperature and 316° C. for coating; When the boiling point of the solvent is greater than the melting point of PVDF, Y°C is less than (the boiling point of the solvent - 5°C); When the boiling point of the solvent is less than or equal to the melting point of the PVDF, the melt dissolution and the second stirring are also carried out under pressure P to keep the solvent in a liquid state; the pressure P is the saturated vapor pressure of the solvent at the stirring temperature*(1.1-1.5).

2. The preparation method according to claim 1, characterized in that The discharge temperature of the electrode slurry is controlled to be between X°C and 316°C for coating.

3. The preparation method according to claim 1, characterized in that The boiling point of the solvent is lower than the cracking temperature of the PVDF.

4. The preparation method according to claim 1, characterized in that The melt dissolution and the second stirring are performed under an inert atmosphere.

5. A non-aqueous electrode plate, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 4.

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