Electrode sheet and preparation method thereof, and energy storage device

Abstract

The present invention discloses an electrode sheet and a preparation method thereof, and an energy storage device. The preparation method of the electrode sheet includes the following steps: fully mixing conductive agent powder and hot melt adhesive powder to obtain a primer raw material, wherein the conductive agent powder includes a first conductive agent, and the first conductive agent is a PTFE-grafted conductive carbon material powder; uniformly dispersing the primer raw material on the current collector, and heat treating the primer raw material to melt to form a primer layer fixed on the current collector; stacking a dry film sheet on the primer layer, and then thermally compounding to obtain the electrode sheet. The preparation method of the electrode sheet of the present invention uses PTFE-grafted conductive carbon material powder as the first conductive agent in the primer layer. PTFE has excellent chemical stability and electrical insulation. By grafting PTFE on the surface of the conductive carbon material powder, the dispersibility of the conductive carbon material powder can be significantly improved, and the conductive carbon material powder is avoided from agglomerating in the primer layer, so that the resistivity difference of the electrode sheet in different areas is small.

Description

Technical Field

[0001] The present invention relates to the field of energy storage devices, and in particular to an electrode sheet and a preparation method thereof, and an energy storage device comprising the electrode sheet. Background Art

[0002] Supercapacitors are new energy storage devices that store energy through the interfacial double layer formed between the electrode sheet and the electrolyte. Due to their high power density and long cycle life, they have broad application prospects in the field of energy storage devices. The electrode sheet is the core part of the supercapacitor. The traditional electrode sheet includes a current collector and an active material layer. The active material is prepared into an active slurry, coated on the current collector, and dried. However, this method has low production efficiency.

[0003] In order to improve the production efficiency of electrode sheets, the industry has developed a dry process for producing electrode sheets, that is, the electrode material is prepared into a dry film sheet, a primer is set on the current collector, and then the current collector, primer and dry film are stacked and hot pressed to bond the three together to obtain an electrode sheet. In order to ensure the bonding strength and conductive properties, the main materials of the primer include adhesives and conductive agents. Commonly used conductive agents are mainly conductive carbon material powders, such as carbon black.

[0004] However, in order to ensure the thickness of the dry film, the thickness of the primer layer is usually 1μm to 6μm. At such a thickness, the conductive carbon material powder is easy to agglomerate, resulting in poor resistivity differences in different regions of the electrode sheet finally prepared and insufficient electrochemical stability. Summary of the invention

[0005] Based on this, it is necessary to provide a method for preparing an electrode sheet that can solve the above problems.

[0006] In addition, it is also necessary to provide an electrode sheet prepared by the above-mentioned method for preparing the electrode sheet and an energy storage device including the electrode sheet.

[0007] A method for preparing an electrode sheet comprises the following steps:

[0008] Dispersing the conductive carbon material powder into an alcohol aqueous solution, then adding PTFE, and mixing thoroughly to make the PTFE evenly distributed on the surface of the conductive carbon material powder to obtain a mixed solution, wherein the mass ratio of the conductive carbon material powder to the PTFE is 1:1 to 10:1;

[0009] The mixed solution is freeze-dried to obtain a semi-finished product, and then the semi-finished product is subjected to plasma treatment to obtain a PTFE-grafted conductive carbon material powder;

[0010] Fully mixing the conductive agent powder and the hot melt adhesive powder to obtain a primer raw material, wherein the conductive agent powder includes a first conductive agent, and the first conductive agent is the PTFE grafted conductive carbon material powder;

[0011] The primer material is evenly dispersed on the current collector, and heat-treated to melt the primer material to form a primer layer fixed on the current collector, wherein the thickness of the primer layer is 1 μm to 6 μm;

[0012] The dry film sheet is stacked on the primer layer, and then thermally compounded so that the current collector, the primer layer and the dry film sheet are sequentially stacked and fixed together to obtain the required electrode sheet, wherein the material of the dry film sheet is the electrode material.

[0013] In one embodiment, the conductive carbon material powder is dispersed in an alcohol aqueous solution, and then PTFE is added, and after sufficient mixing, the PTFE is evenly distributed on the surface of the conductive carbon material powder to obtain the mixed solution. The operation is: adding the conductive carbon material powder to the alcohol aqueous solution, ultrasonically dispersing it uniformly at 0°C to 5°C, and then adding the PTFE, and ultrasonically dispersing it uniformly at 0°C to 5°C again, so that the PTFE is evenly distributed on the surface of the conductive carbon material powder to obtain the mixed solution;

[0014] The PTFE is a PTFE powder containing a surfactant or a dispersion liquid including the PTFE powder containing a surfactant. In the mixed liquid, the concentration of the conductive carbon material powder is 10 g / L to 30 g / L.

[0015] In one embodiment, the particle size of the conductive carbon material powder is 1 nm to 10 μm, and the conductive carbon material powder is carbon black, graphene or carbon nanotubes;

[0016] The particle size of the PTFE is 1 μm to 3 μm, and the PTFE powder Teflon containing surfactant TM MP 1600, Polyflon D-220, Dyneon TM TF 9205, Fluoro GT 200 or In the PTFE powder containing a surfactant, the surfactant is selected from at least one of sodium lauryl sulfate, polyethylene glycol alkyl ether and hexadecyltrimethylammonium bromide;

[0017] In the operation of performing plasma treatment on the semi-finished product, the gas for the plasma treatment is argon, nitrogen or ammonia, the treatment time of the plasma treatment is 5 minutes to 30 minutes, and the power of the plasma treatment is 60W to 200W.

[0018] In one embodiment, the operation of fully mixing the conductive agent powder and the hot melt adhesive powder to obtain the primer raw material is as follows: according to the mass proportion, 50 to 80 parts of the conductive agent powder and 20 to 30 parts of the hot melt adhesive powder are mixed and ball-milled to obtain a mixed dry powder, and the mixed dry powder is subjected to air flow pulverization treatment to obtain the primer raw material;

[0019] The conductive agent powder further includes a second conductive agent, and the mass ratio of the first conductive agent to the second conductive agent is 40-60:10-20.

[0020] In one embodiment, the second conductive agent is selected from at least one of carbon nanotubes and graphene, and the particle size of the second conductive agent is 1 nm to 1 μm;

[0021] The material of the hot melt adhesive powder is plastic hot melt adhesive or polyamide, and the particle size of the hot melt adhesive powder is 0.5μ to 1μm;

[0022] The air flow velocity of the air flow pulverization treatment is 120m / s to 360m / s, and the treatment time of the air flow pulverization treatment is 6min to 30min.

[0023] In one embodiment, the primer raw material is uniformly dispersed on the current collector, and heat-treated to melt the primer raw material to form a primer layer fixed on the current collector. The operation is: electrostatically spraying the primer raw material onto the current collector, and then sequentially performing primary heat treatment and secondary heat treatment to melt the primer raw material to form the primer layer fixed on the current collector.

[0024] In one embodiment, during the electrostatic spraying operation, the spraying voltage is 70 kV to 90 kV, and the distance between the spray gun and the aluminum foil is 10 cm to 15 cm;

[0025] The temperature of the primary heat treatment is 80°C to 100°C, and the time of the primary heat treatment is 1min to 5min;

[0026] The temperature of the secondary heat treatment is 180°C to 200°C, and the time of the secondary heat treatment is 1min to 5min;

[0027] In the operation of stacking and fixing the current collector, the base coating and the dry film sheet in sequence by thermal recombination, the temperature of the thermal recombination is 120° C. to 220° C., the pressure of the thermal recombination is 1t to 10t, and the time of the thermal recombination is 5s to 10s.

[0028] An electrode sheet is prepared by the above-mentioned method for preparing the electrode sheet.

[0029] An energy storage device comprises the above-mentioned electrode sheet.

[0030] In one embodiment, the energy storage device is a secondary battery or a supercapacitor.

[0031] The preparation method of the electrode sheet of the present invention uses PTFE grafted conductive carbon material powder as the first conductive agent in the bottom coating layer. Polytetrafluoroethylene (PTFE) has excellent chemical stability and electrical insulation. By grafting PTFE on the surface of the conductive carbon material powder, the dispersibility of the conductive carbon material powder can be significantly improved, and the conductive carbon material powder is prevented from agglomerating in the bottom coating layer. In combination with the specific embodiment, the electrode sheet prepared by the preparation method of the electrode sheet of the present invention has a small difference in resistivity in different regions and a high electrochemical stability.

[0032] In addition, the PTFE-grafted conductive carbon material powder can also improve the electrochemical stability of the conductive carbon material powder and reduce the degradation of the PTFE-grafted conductive carbon material powder.

[0033] When the electrode sheet prepared by the method for preparing the electrode sheet of the present invention is applied to a supercapacitor, the overall performance of the supercapacitor can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0035] in:

[0036] Figure 1 The present invention is a flow chart of a method for preparing an electrode sheet according to one embodiment.

[0037] Figure 2 This is an electron microscope image of the PTFE grafted carbon black prepared in Example 1.

[0038] Figure 3 CV curve of a 2032-type button-type supercapacitor using the electrode sheet prepared in Example 1. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] Combination Figure 1The present invention discloses a method for preparing an electrode sheet according to an embodiment of the present invention, comprising the following steps:

[0041] S10, dispersing the conductive carbon material powder into an alcohol aqueous solution, then adding PTFE, and mixing thoroughly to make the PTFE evenly distributed on the surface of the conductive carbon material powder to obtain a mixed solution.

[0042] Wherein, the mass ratio of the conductive carbon material powder to PTFE is 1:1 to 10:1.

[0043] Polytetrafluoroethylene (PTFE) has excellent chemical stability and electrical insulation, but its bonding with conductive carbon material powder is poor. By grafting PTFE on the surface of conductive carbon material powder, the electrochemical stability and dispersibility of conductive carbon material powder can be significantly improved.

[0044] Preferably, S10 is: adding the conductive carbon material powder to the alcohol aqueous solution, uniformly dispersing it by ultrasonication at 0°C to 5°C, then adding PTFE, and uniformly dispersing it by ultrasonication again at 0°C to 5°C, so that the PTFE is evenly distributed on the surface of the conductive carbon material powder to obtain a mixed solution.

[0045] The conductive carbon material powder is added to the alcohol-water solution and evenly dispersed by ultrasonication at 0°C to 5°C, which can avoid agglomeration of the conductive carbon material powder and improve the dispersion effect.

[0046] PTFE is added and then evenly dispersed by ultrasonication at 0°C to 5°C, so that the PTFE can be evenly distributed on the surface of the conductive carbon material powder.

[0047] In this embodiment, the alcohol aqueous solution is a mixture of isopropanol and water, wherein the volume ratio of isopropanol to water is 1 to 5:1.

[0048] In other embodiments, the alcohol in the alcohol aqueous solution may also be ethanol, n-butanol or methanol.

[0049] Specifically, the PTFE is a PTFE powder containing a surfactant or a dispersion liquid containing a PTFE powder containing a surfactant, and the concentration of the conductive carbon material powder in the mixed liquid is 10 g / L to 30 g / L.

[0050] The surfactant treatment of PTFE can improve the bonding between PTFE and conductive carbon material powder.

[0051] Specifically, the particle size of the conductive carbon material powder is 10 nm to 60 μm, and the conductive carbon material powder is carbon black, graphite powder or carbon nanotubes.

[0052] Specifically, the particle size of PTFE is 1 μm to 3 μm, and the PTFE powder containing surfactant is TeflonTM MP1600 (Chemours), Polyflon D-220 (Dakin), DyneonTM TF 9205 (3M), Fluoro GT 200 (Shamrock Technologies) or L204 (Solvay), a PTFE powder containing a surfactant, wherein the surfactant is selected from at least one of sodium lauryl sulfate, polyethylene glycol alkyl ether and hexadecyltrimethylammonium bromide.

[0053] S20, freeze-drying the mixed solution obtained in S10 to obtain a semi-finished product, and then plasma-treating the semi-finished product to obtain PTFE-grafted conductive carbon material powder.

[0054] By removing the solvent from the mixed solution through freeze drying, the morphology and distribution of PTFE can be maintained, avoiding the damage to the PTFE structure caused by traditional drying methods.

[0055] Plasma treatment of the semi-finished product can increase the surface functional groups of the conductive carbon material powder and improve the bonding force between PTFE and the conductive carbon material powder.

[0056] Preferably, in the freeze-drying operation of the mixed solution, the freeze-drying temperature is -80°C to -30°C, and the freeze-drying time is 4h to 48h.

[0057] Preferably, in the operation of plasma treating the semi-finished product, the plasma treatment gas is argon, nitrogen or ammonia, the treatment time of the plasma treatment is 5 min to 30 min, and the power of the plasma treatment is 60 W to 200 W.

[0058] S30, fully mixing the conductive agent powder and the hot melt adhesive powder to obtain a primer raw material, wherein the conductive agent powder includes a first conductive agent, and the first conductive agent is the PTFE grafted conductive carbon material powder obtained in S20.

[0059] Preferably, S30 is: according to the mass proportions, 50 to 80 parts of conductive agent powder and 20 to 30 parts of hot melt adhesive powder are mixed and ball-milled to obtain a mixed dry powder, and the mixed dry powder is subjected to air flow pulverization treatment to obtain a primer raw material.

[0060] The air flow milling process uses the energy of compressed air to cause the particles to collide and rub against each other, so that the polymer chains of the hot melt adhesive powder stretch out and intertwine with each other under the action of high-speed shear, forming a physically entangled network structure, which enhances the mechanical strength and conductivity of the final base coating.

[0061] Specifically, the ball milling can be carried out in a ball mill, a small amount of a mixing aid (such as anhydrous ethanol) is added during the ball milling process, and the ball milling time can be 1 hour to 4 hours to ensure that the mixture is evenly distributed, and finally a mixed dry powder is obtained by drying.

[0062] More preferably, in this embodiment, the conductive agent powder further includes a second conductive agent, and the mass ratio of the first conductive agent to the second conductive agent is 40-60:10-20.

[0063] Specifically, the second conductive agent is selected from at least one of carbon nanotubes and graphene, and the particle size of the second conductive agent is 1 nm to 1 μm.

[0064] More preferably, in this embodiment, the material of the hot melt adhesive powder is plastic hot melt adhesive or polyamide, and the particle size of the hot melt adhesive powder is 0.5μ to 1μm.

[0065] Specifically, the plastic hot melt adhesive may be EVA (ethylene-vinyl acetate copolymer).

[0066] More preferably, in this embodiment, the air flow velocity of the air flow pulverization treatment is 120 m / s to 360 m / s, and the treatment time of the air flow pulverization treatment is 6 min to 30 min.

[0067] S40, uniformly dispersing the primer raw material obtained in S30 on the current collector, and subjecting the primer raw material to heat treatment so as to melt the primer raw material to form a primer layer fixed on the current collector, wherein the thickness of the primer layer is 1 μm to 6 μm.

[0068] The current collector can be aluminum foil, copper foil, etched aluminum foil, etched copper foil, etc.

[0069] Preferably, in S30, the primer raw material is evenly dispersed on the current collector, and the primer raw material is heat treated to melt the primer raw material to form a primer layer fixed on the current collector. The operation is: electrostatically spraying the primer raw material onto the current collector, and then performing primary heat treatment and secondary heat treatment in sequence to melt the primer raw material to form a primer layer fixed on the current collector.

[0070] The primary heat treatment can make the primer material slightly melt and initially solidify, while the secondary heat treatment ensures that the primer material is completely solidified and firmly adhered.

[0071] Specifically, electrostatic spraying can be done by multiple thin sprayings, with surface inspection after each spraying to ensure there is no missing paint or accumulation.

[0072] More preferably, in the present embodiment, during the electrostatic spraying operation, the spraying voltage is 70 kV to 90 kV, and the distance between the spray gun and the aluminum foil is 10 cm to 15 cm.

[0073] More preferably, in this embodiment, the temperature of the primary heat treatment is 80° C. to 100° C., and the time of the primary heat treatment is 1 min to 5 min.

[0074] More preferably, in this embodiment, the temperature of the secondary heat treatment is 180° C. to 200° C., and the time of the secondary heat treatment is 1 min to 5 min.

[0075] Specifically, the secondary heat treatment can be accomplished by a secondary forced air oven.

[0076] S50, stacking the dry film sheet on the base coating layer formed in S40, and then thermally compounding the current collector, the base coating layer and the dry film sheet so as to be sequentially stacked and fixed together to obtain the required electrode sheet.

[0077] The material of the dry film is the electrode material.

[0078] Dry film sheets can be purchased directly or prepared by yourself.

[0079] In this embodiment, the dry film can be purchased from Guangdong Qingyan Electronics Co., Ltd., with a thickness of 100 μm to 140 μm, and its materials are activated carbon, conductive agent SP, binder PTFE and pore-forming agent anhydrous citric acid in a mass ratio of 80:10:8:2.

[0080] Preferably, in S50, in the operation of thermally compounding so that the current collector, the primer layer and the dry film are sequentially stacked and fixed together, the temperature of the thermal compounding is 120° C. to 220° C., the pressure of the thermal compounding is 1t to 10t, and the time of the thermal compounding is 5s to 10s.

[0081] Specifically, thermal lamination can be achieved by using a roll-pressing film-forming process.

[0082] By adjusting the temperature and pressure parameters of roller-pressing film formation, the uniformity and adhesion of the electrode membrane can be improved.

[0083] The preparation method of the electrode sheet of the present invention uses PTFE grafted conductive carbon material powder as the first conductive agent in the bottom coating layer. Polytetrafluoroethylene (PTFE) has excellent chemical stability and electrical insulation. By grafting PTFE on the surface of the conductive carbon material powder, the electrochemical stability and dispersibility of the conductive carbon material powder can be significantly improved, and the conductive carbon material powder is prevented from agglomerating in the bottom coating layer. In combination with the specific embodiment, the electrode sheet prepared by the preparation method of the electrode sheet of the present invention has a small difference in resistivity in different regions and a high electrochemical stability.

[0084] In addition, the PTFE-grafted conductive carbon material powder can also improve the electrochemical stability of the conductive carbon material powder and reduce the degradation of the PTFE-grafted conductive carbon material powder.

[0085] The present invention also discloses an embodiment of an electrode sheet prepared by the above-mentioned method for preparing the electrode sheet.

[0086] The electrode sheet prepared by the method for preparing the electrode sheet of the present invention can be applied to various fields, for example, in the field of energy storage.

[0087] The present invention also discloses an energy storage device according to an embodiment, comprising the electrode sheet mentioned above.

[0088] Specifically, the energy storage device may be a secondary battery or a supercapacitor.

[0089] When the electrode sheet prepared by the method for preparing the electrode sheet of the present invention is applied to a supercapacitor, the overall performance of the supercapacitor can be improved.

[0090] The following are specific embodiments.

[0091] In a specific embodiment, the dry active membrane is purchased from Guangdong Qingyan Electronics Co., Ltd., has a thickness of 120 μm, and its materials are activated carbon, conductive agent SP, binder PTFE and pore-forming agent anhydrous citric acid in a mass ratio of 80:10:8:2.

[0092] Example 1

[0093] 1) Preparation of PTFE grafted carbon black.

[0094] 5 g of carbon black powder (Termical, SUPER P Li, 40 nm) was added to 500 mL of a mixed solvent of isopropanol and water (volume ratio: isopropanol / water = 2) and dispersed for 1 h using an ultrasonic oscillator (0°C). 2 mL of 60% by mass PTFE (Teflon TM MP 1600 (Chemours)) dispersion, and then ultrasonically dispersed for 1 hour under low temperature conditions. TM Freezone TM The PTFE was pre-frozen at -80℃ in a vertical freeze dryer for 0.5h; then vacuumed to 1.0 Torr, and freeze-dried at -20℃ for 24h under this vacuum to maintain the morphology and distribution of PTFE. Then, it was kept at room temperature for 4h to remove the residual bound water. It was moved to a plasma treatment device, and oxygen was introduced into the reaction chamber. The flow rate was set to 10sccm, the power was 100W, and the treatment time was 15min to obtain PTFE-grafted carbon black.

[0095] 2) Preparation of electrode sheets.

[0096] The prepared PTFE grafted carbon black, carbon nanotubes (Jiangsu Tiannai, FT700), and hot melt adhesive powder (Wenzhou Huate, HT-9260) were mixed in a ball mill with a mass percentage of 60:20:20. During the mixing process, 0.1% isopropanol was slowly dripped in to assist mixing. The mixing process was carried out at a stirring speed of 100 rpm for 20 minutes to obtain a uniformly dispersed mixed powder.

[0097] The mixture was pulverized in a jet mill, and the compressed atmosphere used was air, the gas flow rate was 200m / s, and the time was 20min. In the drying room, the powder after the air flow pulverization was poured into the hopper of the spraying equipment, and through the automatic feeding system, it was effectively and continuously sprayed on the surface of the aluminum foil (Japan JCC, 20CB) with a thickness of 20μm, and then multi-stage cured in an oven to form a coated aluminum foil with a coating of 1μm. The spraying parameters were set as follows: the spraying voltage of the electrostatic powder spraying equipment was 75kV, and the distance between the spray gun and the aluminum foil was 12cm; the primary heat treatment temperature was 100℃, the time was 1min; the secondary heat treatment temperature was 120℃, and the time was 2min.

[0098] The dry active membrane was placed on both sides of the double-sided coated aluminum foil and put into a thermal composite machine for rolling so that the membrane and the current collector were tightly and evenly bonded together to prepare an electrode sheet. The thermal composite temperature was 130°C, the thermal composite pressure was 5.5t, and the thermal composite time was 8s.

[0099] Example 2

[0100] 1) Preparation of PTFE grafted carbon black.

[0101] 9 g of carbon black powder (Termical, SUPER P Li, 40 nm) was added to 500 ml of a mixed solvent of isopropanol and water (volume ratio: isopropanol / water = 2), and dispersed evenly at low temperature (2° C.) using an ultrasonic oscillator for 2 hours. 15 mL of a 60% by mass PTFE (Polyflon D-220 (Dakin)) dispersion containing a surfactant was added to the carbon black dispersion, and ultrasonically dispersed again at low temperature for 1.5 hours.

[0102] The plasma treatment parameters were set as follows: argon gas, 100 W power, and 15 min treatment time.

[0103] The rest is the same as Example 1.

[0104] 2) Preparation of electrode sheets.

[0105] The prepared PTFE grafted carbon black, carbon nanotubes (Tian Nai, Jiangsu, FT700), and hot melt adhesive powder (Huate, Wenzhou, HT-H18) were mixed in a ball mill with a mass percentage of 50:25:25. During the mixing process, 0.1% isopropanol was slowly dripped in to assist mixing. The mixing process was carried out at a stirring speed of 500 rpm for 40 minutes to obtain a uniformly dispersed mixed powder.

[0106] The mixture was pulverized in a jet mill, and the compressed atmosphere used was air, the gas flow rate was 200m / s, and the time was 20min. In the drying room, the powder after the air flow pulverization was poured into the hopper of the spraying equipment, and through the automatic feeding system, it was effectively and continuously sprayed on the surface of the aluminum foil (Japan JCC, 20CB) with a thickness of 20μm, and then multi-stage cured in an oven to form a coated aluminum foil with a coating of 3μm. The spraying parameters were set as follows: the spraying voltage of the electrostatic powder spraying equipment was 75kV, and the distance between the spray gun and the aluminum foil was 12cm; the primary heat treatment temperature was 100℃, the time was 1min; the secondary heat treatment temperature was 140℃, and the time was 2min.

[0107] The dry active membrane was placed on both sides of the double-sided coated aluminum foil and put into a thermal composite machine for rolling so that the membrane and the current collector were tightly and evenly bonded together to prepare an electrode sheet. The thermal composite temperature was 220°C, the thermal composite pressure was 1t, and the thermal composite time was 5s.

[0108] Example 3

[0109] 1) Preparation of PTFE grafted carbon black.

[0110] 6 g of carbon black powder (Termical, SUPER P Li, 40 nm) was added to 500 ml of a mixed solvent of methanol and water (volume ratio: methanol / water = 1), and dispersed evenly at low temperature (5°C) using an ultrasonic oscillator for 1 hour. 1 mL of 60% by mass PTFE (Dyneon TM TF 9205 (3M)) dispersion was dispersed by ultrasonication again at low temperature for 2 hours.

[0111] The rest is the same as Example 1.

[0112] 2) Preparation of electrode sheets.

[0113] The prepared PTFE grafted carbon black, carbon nanotubes (Jiangsu Tiannai, FT700), and hot melt adhesive powder (Wenzhou Huate, HT-L50) were mixed in a ball mill with a mass percentage of 60:20:20. During the mixing process, 0.1% isopropanol was slowly dripped in to assist mixing. The mixing process was carried out at a stirring speed of 3000 rpm for 30 minutes to obtain a uniformly dispersed mixed powder.

[0114] The mixture was pulverized in a jet mill, and the compressed atmosphere used was air, the gas flow rate was 200m / s, and the time was 30min. In the drying room, the powder after the air flow pulverization was poured into the hopper of the spraying equipment, and through the automatic feeding system, it was effectively and continuously sprayed on the surface of the aluminum foil (Japan JCC, 20CB) with a thickness of 20μm, and then multi-stage cured in an oven to form a coated aluminum foil with a coating of 6μm. The spraying parameters were set as follows: the spraying voltage of the electrostatic powder spraying equipment was 75kV, and the distance between the spray gun and the aluminum foil was 12cm; the primary heat treatment temperature was 100℃, the time was 1min; the secondary heat treatment temperature was 160℃, and the time was 2min.

[0115] The dry active membrane was placed on both sides of the double-sided coated aluminum foil and put into a thermal composite machine for rolling so that the membrane and the current collector were tightly and evenly bonded together to prepare an electrode sheet. The thermal composite temperature was 120°C, the thermal composite pressure was 10t, and the thermal composite time was 10s.

[0116] Comparative Example 1

[0117] PTFE powder (Teflon TM MP 1600 (Chemours)) and carbon black powder (Termical, SUPER P Li, 40nm) were mixed in a mass ratio of 5:1.2 to obtain a mixed powder. The mixed powder, carbon black powder (Termical, SUPER PLi, 40nm) mixture, carbon nanotubes (Jiangsu Tiannai, FT700), and hot melt adhesive powder (Wenzhou Huate, HT-9260) were mixed in a ball mill with a mass percentage of 60:20:20. During the mixing process, 0.1% isopropanol was slowly dripped in to assist mixing. The mixing process was carried out at a stirring speed of 500rpm for 40min to obtain a uniformly dispersed mixed powder.

[0118] The mixture was pulverized in a jet mill, and the compressed atmosphere used was air, the gas flow rate was 200m / s, and the time was 20min. In the drying room, the powder after the air flow pulverization was poured into the hopper of the spraying equipment, and through the automatic feeding system, it was effectively and continuously sprayed on the surface of the aluminum foil (Japan JCC, 20CB) with a thickness of 20μm, and then multi-stage cured in an oven to form a coated aluminum foil with a coating of 3μm. The spraying parameters were set as follows: the spraying voltage of the electrostatic powder spraying equipment was 75kV, and the distance between the spray gun and the aluminum foil was 12cm; the primary heat treatment temperature was 100℃, the time was 1min; the secondary heat treatment temperature was 140℃, and the time was 2min.

[0119] The dry active membrane was placed on both sides of the double-sided coated aluminum foil and put into a thermal composite machine for rolling so that the membrane and the current collector were tightly and evenly bonded together to prepare an electrode sheet. The thermal composite temperature was 220°C, the thermal composite pressure was 1t, and the thermal composite time was 100s.

[0120] Comparative Example 2

[0121] Carbon black powder (Termical, SUPER P Li, 40nm), carbon nanotubes (Jiangsu Tiannai, FT700), and hot melt adhesive powder (Wenzhou Huate, HT-9260) were mixed in a ball mill with a mass percentage of 60:20:20. During the mixing process, 0.1% isopropanol was slowly dripped in to assist mixing. The mixing process was carried out at a stirring speed of 500 rpm for 40 minutes to obtain a uniformly dispersed mixed powder.

[0122] The mixture was pulverized in a jet mill, and the compressed atmosphere used was air, the gas flow rate was 200m / s, and the time was 20min. In the drying room, the powder after the air flow pulverization was poured into the hopper of the spraying equipment, and through the automatic feeding system, it was effectively and continuously sprayed on the surface of the aluminum foil (Japan JCC, 20CB) with a thickness of 20μm, and then multi-stage cured in an oven to form a coated aluminum foil with a coating of 3μm. The spraying parameters were set as follows: the spraying voltage of the electrostatic powder spraying equipment was 75kV, and the distance between the spray gun and the aluminum foil was 12cm; the primary heat treatment temperature was 100℃, the time was 1min; the secondary heat treatment temperature was 140℃, and the time was 2min.

[0123] The dry active membrane was placed on both sides of the double-sided coated aluminum foil and put into a thermal composite machine for rolling so that the membrane and the current collector were tightly and evenly bonded together to prepare an electrode sheet. The thermal composite temperature was 220°C, the thermal composite pressure was 1t, and the thermal composite time was 100s.

[0124] Test Case

[0125] 1) Electron microscopy observation.

[0126] The PTFE grafted carbon black prepared in Example 1 was observed under an electron microscope, and the Figure 2 .

[0127] Combination Figure 2 , it can be seen that the carbon black particles and PTFE particles are evenly dispersed with each other, and PTFE particles are distributed on each carbon black particle.

[0128] 2) Coated aluminum foil performance test.

[0129] The coated aluminum foils prepared in Examples 1 to 3 and Comparative Examples 1 to 2 were cut into small discs with a diameter of 14 mm, and then subjected to the following tests: randomly selected points were used to measure the coating thickness and uniformity using a thickness gauge to ensure the coating thickness; the coated aluminum foil was visually inspected to ensure that there were no defects such as bubbles and cracks; and electrical conductivity tests and mechanical property tests were performed to ensure that the coating had the expected electrical conductivity and durability.

[0130] The test results are shown in Table 1 below.

[0131] Table 1: Coated aluminum foil performance test

[0132]

[0133] It can be seen from Table 1 that the unit resistance deviation value of the coated aluminum foil prepared in Examples 1 to 3 is significantly lower than that of the coated aluminum foil prepared in Comparative Examples 1 to 2, which indicates that the resistivity difference of the coated aluminum foil prepared in Examples 1 to 3 in different regions is small and the electrochemical stability is high.

[0134] 3) Electrode performance test.

[0135] The electrode sheet prepared in Example 1 was cut into a circular electrode sheet with a diameter of 14 mm and assembled with a diaphragm (NKK, TF40, Japan) into a 2032-type button-type supercapacitor, wherein the electrolyte was New Energy Battery DLC3702. Cyclic voltammetry test was performed on an electrochemical workstation.

[0136] The potential range was set to -0.2V to 3.5V, and the scan rate was 0.5mV / s to 500mV / s. The CV curves of multiple cycles were recorded to evaluate the electrode stability. Figure 3 .

[0137] Combination Figure 3 It can be seen that the current response of the 2032-type button-type supercapacitor assembled using the electrode sheet prepared in Example 1 is consistent, and no abnormal peak occurs. This shows that the electrode sheet prepared in Example 1 has good electrochemical stability, and its specific capacitance and cycle life are significantly improved.

[0138] In the description of the embodiments of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limitations on the embodiments of the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0139] In the description of the embodiments of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0140] In the embodiments of the present invention, unless otherwise clearly specified and limited, the first feature being "above" or "below" the second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "above" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0141] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0142] 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 embodiments of the present invention.

Claims

1. A method for preparing an electrode sheet, characterized in that: The steps include: Dispersing the conductive carbon material powder into an alcohol aqueous solution, then adding PTFE, and mixing thoroughly to make the PTFE evenly distributed on the surface of the conductive carbon material powder to obtain a mixed solution, wherein the mass ratio of the conductive carbon material powder to the PTFE is 1:1 to 10:1, the PTFE is a PTFE powder containing a surfactant or a dispersion of the PTFE powder containing a surfactant, and the concentration of the conductive carbon material powder in the mixed solution is 10 g / L to 30 g / L; The mixed solution is freeze-dried to obtain a semi-finished product, and then the semi-finished product is subjected to plasma treatment to obtain a PTFE-grafted conductive carbon material powder; Fully mixing the conductive agent powder and the hot melt adhesive powder to obtain a primer raw material, wherein the conductive agent powder includes a first conductive agent, and the first conductive agent is the PTFE grafted conductive carbon material powder; The primer material is evenly dispersed on the current collector, and heat-treated to melt the primer material to form a primer layer fixed on the current collector, wherein the thickness of the primer layer is 1 μm to 6 μm; The dry film sheet is stacked on the primer layer, and then thermally compounded so that the current collector, the primer layer and the dry film sheet are sequentially stacked and fixed together to obtain the required electrode sheet, wherein the material of the dry film sheet is the electrode material.

2. The method for preparing an electrode sheet according to claim 1, characterized in that: The conductive carbon material powder is dispersed in an alcohol-water solution, and then PTFE is added. After sufficient mixing, the PTFE is evenly distributed on the surface of the conductive carbon material powder to obtain the mixed solution. The operation is as follows: the conductive carbon material powder is added to the alcohol-water solution, and ultrasonically dispersed at 0°C to 5°C, and then the PTFE is added, and ultrasonically dispersed again at 0°C to 5°C to make the PTFE evenly distributed on the surface of the conductive carbon material powder to obtain the mixed solution.

3. The method for preparing an electrode sheet according to claim 2, characterized in that: The particle size of the conductive carbon material powder is 1 nm to 20 μm, and the conductive carbon material powder is carbon black, graphene or carbon nanotubes; The particle size of the PTFE is 1 μm to 3 μm, and the PTFE powder containing a surfactant is Teflon TM MP 1600, Polyflon D-220, Dyneon TM TF 9205, Fluoro GT 200 or L204, in the PTFE powder containing a surfactant, the surfactant is selected from at least one of sodium lauryl sulfate, polyethylene glycol alkyl ether and hexadecyltrimethylammonium bromide; In the operation of performing plasma treatment on the semi-finished product, the gas for the plasma treatment is argon, nitrogen or ammonia, the treatment time of the plasma treatment is 5 minutes to 30 minutes, and the power of the plasma treatment is 60W to 200W.

4. The method for preparing an electrode sheet according to any one of claims 1 to 3, characterized in that: The operation of fully mixing the conductive agent powder and the hot melt adhesive powder to obtain the primer raw material is as follows: according to the mass parts, 50 to 80 parts of the conductive agent powder and 20 to 30 parts of the hot melt adhesive powder are mixed and ball-milled to obtain a mixed dry powder, and the mixed dry powder is subjected to air flow pulverization treatment to obtain the primer raw material; The conductive agent powder further includes a second conductive agent, and the mass ratio of the first conductive agent to the second conductive agent is 40-60:10-20.

5. The method for preparing an electrode sheet according to claim 4, characterized in that: The second conductive agent is selected from at least one of carbon nanotubes and graphene, and the particle size of the second conductive agent is 1 nm to 1 μm; The material of the hot melt adhesive powder is plastic hot melt adhesive or polyamide, and the particle size of the hot melt adhesive powder is 0.5μ to 1μm; The air flow velocity of the air flow pulverization treatment is 120m / s to 360m / s, and the treatment time of the air flow pulverization treatment is 6min to 30min.

6. The method for preparing an electrode sheet according to claim 4, characterized in that: The operation of uniformly dispersing the primer raw material on the current collector and heat treating the primer raw material to melt it to form a primer layer fixed on the current collector is as follows: electrostatically spraying the primer raw material onto the current collector, and then sequentially performing primary heat treatment and secondary heat treatment to melt the primer raw material to form the primer layer fixed on the current collector.

7. The method for preparing an electrode sheet according to claim 6, characterized in that: During the electrostatic spraying operation, the spraying voltage is 70 kV to 90 kV, and the distance between the spray gun and the aluminum foil is 10 cm to 15 cm; The temperature of the primary heat treatment is 80°C to 100°C, and the time of the primary heat treatment is 1min to 5min; The temperature of the secondary heat treatment is 180°C to 200°C, and the time of the secondary heat treatment is 1min to 5min; In the operation of stacking and fixing the current collector, the base coating and the dry film sheet in sequence by thermal recombination, the temperature of the thermal recombination is 120° C. to 220° C., the pressure of the thermal recombination is 1t to 10t, and the time of the thermal recombination is 5s to 10s.

8. An electrode sheet, characterized in that: The electrode sheet is prepared by the method for preparing the electrode sheet according to any one of claims 1 to 7.

9. An energy storage device, characterized in that: Comprising the electrode sheet as claimed in claim 8.

10. The energy storage device according to claim 9, characterized in that: The energy storage device is a secondary battery or a super capacitor.

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