CN116168959B - Low-gas-yield dry electrode plate, super capacitor and preparation method - Google Patents
Low-gas-yield dry electrode plate, super capacitor and preparation method Download PDFInfo
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- CN116168959B CN116168959B CN202310311777.9A CN202310311777A CN116168959B CN 116168959 B CN116168959 B CN 116168959B CN 202310311777 A CN202310311777 A CN 202310311777A CN 116168959 B CN116168959 B CN 116168959B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
- H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
- H01G11/84—Processes for the manufacture of hybrid or EDL capacitors, or components thereof
- H01G11/86—Processes for the manufacture of hybrid or EDL capacitors, or components thereof specially adapted for electrodes
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
- H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
- H01G11/22—Electrodes
- H01G11/26—Electrodes characterised by their structure, e.g. multi-layered, porosity or surface features
- H01G11/28—Electrodes characterised by their structure, e.g. multi-layered, porosity or surface features arranged or disposed on a current collector; Layers or phases between electrodes and current collectors, e.g. adhesives
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
- H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
- H01G11/22—Electrodes
- H01G11/30—Electrodes characterised by their material
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- 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
Abstract
The invention relates to a low-yield gas dry electrode slice, a super capacitor and a preparation method thereof, which relate to the technical field of super capacitors and comprise the following steps: step 1: mixing an active material with a film-forming agent dry powder to obtain a mixture I; step 2: heating to perform exhaust treatment, cooling the mixture I after the exhaust treatment in a sealing state, and introducing dry gas into the cooled mixture I in the sealing state to obtain the treated mixture I; step 3: mixing with a conductive agent and a binder to obtain a mixture II; step 4: carrying out fluffing treatment to obtain a fluffed mixture II; step 5: rolling to form an electrode film; step 6: and compounding with a metal current collector to form the electrode plate with a sandwich structure. The supercapacitor manufactured by the electrode plate can effectively reduce the gas production amount of the electrode plate in the use process, effectively prolong the service life of the supercapacitor and reduce the cost of the supercapacitor.
Description
Technical Field
The invention relates to the technical field of super capacitors, in particular to a low-yield gas dry electrode slice, a super capacitor and a preparation method.
Background
Super capacitor refers to a new energy storage device between traditional capacitor and rechargeable battery, its capacity can reach several hundred to thousands of farads. Compared with the traditional capacitor, the capacitor has larger capacity, specific energy or energy density, wider working temperature range and extremely long service life; compared with accumulator, it has higher specific power and no environmental pollution. The method is successfully applied to the technical fields of consumer electronics products (such as computers and the like), energy traffic (such as electric automobiles, solar energy and wind energy storage and the like), medical appliances, communication equipment, power compensation and the like.
The super capacitor pole piece adopts a dry production process, no organic solvent or water is added in the production process, so that baking is not needed, no discharge is generated, and the production process is an ideal production process for the capacitor pole piece. The dry preparation process of the domestic super capacitor pole piece is mature gradually. The dry pole piece preparation process flow is generally that firstly active substances, conductive agents and binder powder are dry-mixed by a mixing device, then the obtained mixture I is subjected to fiberization of the binder under the action of shearing force of air flow, and then the mixture I is subjected to roll forming. For example, patent number CN 102629681B discloses a powder-based electrode forming method. However, the prepared pole piece has the defects of potential safety hazard and short service life in the application process, and one of the biggest reasons for the defects is that the powder can generate oxygen-containing functional groups and other active sites in the activation process, and the oxygen-containing functional groups and other active sites can generate side reactions with electrolyte to generate harmful products such as gas. The generated harmful products can cause the interface of the battery core of the super capacitor manufactured by the pole piece to be poor, the internal resistance to be increased and the capacity to be reduced, and even the pole piece can be deformed, so that the battery core is finally short-circuited, burnt or exploded. Therefore, reducing the gas production of the pole piece in the using process is a technical problem to be solved in the super capacitor industry.
The prior art generally discharges and adsorbs the generated gas of the pole piece and the electrolyte to solve the problems. For example, patent publication number CN 113077994B discloses a pole piece for super capacitor, which comprises the following raw materials in parts by weight: 90-98 parts of active carbon, 2-4 parts of modifier, 1-3 parts of conductive agent and 0.5-1.5 parts of adhesive. Through effectively building pole piece overall structure, effectively get rid of unable easy exhaust gas in the pore. The patent with publication number CN 110767464B discloses a super capacitor containing MOFs material and a preparation method thereof, wherein the super capacitor comprises a battery cell, a gas storage sheet and a shell; the battery cell comprises a pole piece and an isolating film, wherein the pole piece comprises a current collector, a first MOFs coating arranged on the surface of the current collector and a pole piece active coating arranged on the surface of the first MOFs coating; the gas storage sheet is arranged in the inner cavity of the shell and comprises a conductive carrier and a second MOFs coating arranged on the surface of the conductive carrier. The patent solves the problem of internal gas production in the long-term use process by coating a second MOFs coating on the surface of the conductive carrier to prepare the gas storage sheet. However, the above-mentioned patents have problems that the process of the pole piece is complicated, time-consuming, and the materials used are expensive. In view of the above, the invention provides a low-yield gas dry method electrode slice, a super capacitor and a preparation method.
Disclosure of Invention
The invention aims to solve the technical problem of providing a low-yield gas dry method electrode slice, a super capacitor and a preparation method. The purpose is to effectively reduce the gas production in the use of the capacitor pole piece, effectively improve the service life of the super capacitor, and reduce the cost of the super capacitor.
The invention aims to solve the technical problems, and a first aim is to provide a preparation method of a low-yield gas-drying electrode slice, which comprises the following steps:
step 1: mixing for the first time according to the mass ratio of the active material to the film forming agent dry powder of 95:5-99:1, wherein the stirring speed of the first mixing is 200-400 r/min, and the stirring time is 0.5-3 h, so as to obtain a mixture I;
step 2: heating the mixture I to 100-200 ℃ for exhaust treatment, cooling the mixture I after exhaust treatment to 0-35 ℃ in a sealing state after the temperature is kept constant for at least 30min, and introducing dry gas into the mixture I after cooling in the sealing state, wherein the flow rate of the dry gas is 10-20 m/s, and the introducing time of the dry gas is 1-6 s, so as to obtain the mixture I after treatment;
step 3: mixing the treated mixture I with a conductive agent and a binder for the second time according to the mass ratio of 80:10:10-95:2.5:2.5, wherein the stirring speed of the second mixing is 800-1200 r/min, and the stirring time is 2-4 h, so as to obtain a mixture II;
step 4: carrying out fluffing treatment on the mixture II under the condition that the gas pressure is 0.3-0.8 Mpa and the feeding speed is 30-300 g/min to obtain a fluffed mixture II;
step 5: rolling the fluffed mixture II into an electrode film, wherein the temperature of the rolled electrode film is 80-250 ℃, and the speed is less than or equal to 20m/min, so as to obtain the electrode film with target thickness; wherein the electrode film of the target thickness has different values as required, for example, 61 μm, 77 μm, 92 μm, 107 μm, etc.;
step 6: and sequentially carrying out three-layer rolling compounding on the electrode film, the metal current collector and the electrode film with target thickness, wherein the temperature of the three-layer rolling compounding is 80-250 ℃, and the speed is less than or equal to 20m/min, so as to form the electrode plate with the sandwich structure of the electrode film/the metal current collector/the electrode film.
The main principle of the invention is as follows: firstly, mixing an active material and film forming agent dry powder according to a certain mass ratio to obtain a mixture I, heating the mixture I to 100-200 ℃ for exhaust treatment, desorbing and discharging adsorbed gas in an inner hole of the active material, then cooling in a sealed state, and forming a low-pressure microenvironment (similar to vacuum) by utilizing the change of temperature difference to improve the adsorption capacity of the active material. And then, instantly introducing dry gas, forming weak air flow when the dry gas enters the inner holes of the active materials, and taking the film forming agent dry powder which is pre-mixed in the mixture I and is arranged at the edges of the holes of the active materials into the inner holes of the active materials by the weak air flow, so that the film forming agent dry powder exists not only on the outer surface of the active materials but also in the inner holes of the active materials, and forming a comprehensive isolation protective film. Finally, when electrolyte enters into the active material holes for charge and discharge, as a certain amount of film forming agents are distributed on the outer surface and the inner holes of the active material, the film forming agents can form protective films preferentially on the outer surface and the inner holes of the active material, and the surface active points of the active material are prevented from further reacting with the electrolyte, so that the gas production of the pole piece is reduced.
If the film forming agent dry powder and the active material are simply mixed, and the film forming agent dry powder cannot enter the inner holes of the active material, the film is formed on the outer surface of the active material, the inner hole active points of the active material are not closed, the active points in the holes of the active material still react with electrolyte to generate gas, and the gas generation blocking effect of the film forming agent can be reduced.
In a word, the film forming agent is added to prevent the electrolyte from reacting with the active site of the active material, and is placed in the inner hole of the active carbon by utilizing the characteristic of the active material of high adsorption capacity to gas molecules, so that the purposes of preventing the surface active site of the active material from further reacting with the electrolyte and reducing the gas production of the pole piece are achieved, the service life of the supercapacitor is effectively prolonged, and the cost of the supercapacitor is reduced.
The beneficial effects of the invention are as follows:
(1) The invention can effectively reduce the gas production in the use process of the capacitor pole piece, effectively prolong the service life of the capacitor and reduce the cost of the capacitor;
(2) The production and preparation process of the invention does not need any organic solvent, and can realize zero pollution;
(3) The preparation method of the invention adopts the mature dry process and equipment in the industry at present, and devices and the like used for the pretreatment are mature equipment in the industry without investment and development, so that the production can be carried out under the condition of basically not increasing the cost, thereby enhancing the price competitiveness of the product of the invention.
Further, the treatment in the step 2 can be performed in a tank body with a valve, the mixture I is subjected to exhaust treatment by opening the valve, and the tank body is sealed by closing the valve in the process of cooling; the steps 1 and 3 are carried out in the powder mixer for the first and the second mixing; step 4, processing in a wire drawing machine; the above steps 5 and 6 use high Wen Nian press rolls, and the electrode sheet with the sandwich structure of electrode film/metal current collector/electrode film is formed by adjusting to the required thickness through a plurality of rolling machines according to the product requirement.
The beneficial effects of adopting the further scheme are as follows: the method has the advantages of simple equipment, simple and convenient operation process, effective reduction of labor intensity of workers, suitability for popularization, simple and quick process, easy operation, low requirements on equipment in the production process and convenience for actual production operation.
On the basis of the technical scheme, the invention can be improved as follows.
Further, in the step 1, the mass ratio of the active material to the film forming agent dry powder is 96:4-99: 1, carrying out primary mixing, wherein the stirring speed of the primary mixing is 250-350 r/min, and the stirring time is 1-2 h, so as to obtain a mixture I.
The beneficial effects of adopting the further scheme are as follows: the proportion of the active material and the film forming agent is further optimized, so that the capacity exertion of the active material is prevented from being influenced by excessive content of the film forming agent; meanwhile, the stirring rotation speed and the stirring time are optimized, and the energy consumption is minimum on the premise of ensuring uniform material mixing.
In step 2, the mixture I is heated to 120-180 ℃ for exhaust treatment, after the temperature is kept constant for at least 30min, the temperature of the mixture I after the exhaust treatment is reduced to 0-25 ℃ in a sealing state, and dry gas is introduced into the mixture I after the temperature reduction in the sealing state, wherein the flow rate of the dry gas is 12-18 m/s, and the time for introducing the dry gas is 2-4 s, so that the mixture I after the treatment is obtained.
The beneficial effects of adopting the further scheme are as follows: further optimizing the process parameters to allow as much of the film former to enter the active material pores as possible.
Further, the active material is any one or a mixture of at least two of active carbon, nano carbon fiber, glass carbon, carbon aerogel and carbon nano tube; the film forming agent dry powder comprises any one or a mixture of at least two of lithium carbonate, lithium difluorophosphate, lithium bisoxalato borate and sodium carboxymethyl cellulose.
Further, the dry gas is any one or a mixture of at least two of compressed air, nitrogen and helium.
In the step 3, the treated mixture I, the conductive agent and the binder are mixed for the second time according to the mass ratio of 85:5:10-90:5:5, the stirring speed of the second mixing is 900-1100 r/min, and the stirring time is 2.5-3.5 h, so that a mixture II is obtained;
in the step 4, the mixture II is subjected to fluffing treatment under the condition that the gas pressure is 0.4-0.7 Mpa and the feeding speed is 100-200 g/min, so as to obtain the fluffed mixture II.
The beneficial effects of adopting the further scheme are as follows: further optimizing the process parameters, ensuring that the mixture is fluffy uniformly and uniformly treated, and having the lowest energy consumption. If the mixture is too fluffy, the subsequent electrode film is not compacted sufficiently, and if the mixture is fluffy to an insufficient extent, the subsequent film is not deformed uniformly and is easy to wrinkle.
In the step 5, the fluffy mixture II is rolled into an electrode film, the temperature of the rolled electrode film is 100-200 ℃, and the speed is less than or equal to 15m/min, so that the electrode film with the target thickness is obtained;
in the step 6, the electrode film and the metal current collector with target thickness are sequentially laminated and compounded by three layers of the electrode film, the metal current collector and the electrode film, wherein the temperature of the laminated and compounded three layers is 100-200 ℃, and the speed is less than or equal to 15m/min, so that the electrode plate with a sandwich structure of the electrode film/the metal current collector/the electrode film is formed.
The beneficial effects of adopting the further scheme are as follows: under the condition of ensuring good adhesion between the electrode film and the current collector, energy waste is avoided, and the production efficiency is highest.
Further, the conductive agent comprises any one or a mixture of at least two of metal powder (the metal powder comprises gold powder, silver powder or copper powder), acetylene black, ketjen black, furnace black, conductive carbon black, conductive graphite, carbon nanotubes, carbon fibers and graphene;
the binder comprises any one or a mixture of at least two of polytetrafluoroethylene, polyvinylidene fluoride and polyvinyl alcohol;
the metal current collector is copper foil or aluminum foil.
The second object of the invention is to provide a low-yield gas dry electrode slice, which is prepared by the preparation method according to any one of the above.
The second object of the invention is to provide a super capacitor, which comprises the electrode plate with low gas production.
Drawings
FIG. 1 is a comparison of SEM of example I and example V of the present invention, wherein (a) SEM of mixture I of example I and (b) SEM of activated carbon;
FIG. 2 is a graph showing comparison of the results of gas production according to embodiments one to five of the present invention;
FIG. 3 is a graph showing the capacity fade performance versus the pole pieces of examples one through five of the present invention;
fig. 4 is a graph showing the internal resistance increase performance of the pole pieces according to the first to fifth embodiments of the present invention.
Detailed Description
The principles and features of the present invention are described below with examples given for the purpose of illustration only and are not intended to limit the scope of the invention.
Example 1
The embodiment relates to a preparation method of a low-yield gas dry electrode slice, which comprises the following steps:
step 1: adding active carbon and film forming agent dry powder into a mixer according to a mass ratio of 99:1, setting a mixing speed of 300r/min, and mixing for 2 hours to obtain a mixture I;
step 2: placing the mixture I obtained in the step 1 in a tank body with a valve, heating to 150 ℃, closing the valve (forming a sealed environment) after the temperature is uniform for 30min, and then cooling the tank body and powder to 25 ℃; introducing dry compressed air into the cooled tank body, wherein the flow rate of the dry air is 15m/s, and the introducing time of the dry air is 3s, so as to obtain a treated mixture I, and the treated mixture I is shown in figure 1;
step 3: adding the mixture I obtained in the step 2, a conductive agent and a binder into a powder mixer according to the proportion of 90:5:5 for powder mixing, wherein the stirring speed of the mixer is 1000r/min, and the powder mixing time is 3h, so as to obtain a mixture II;
step 4: adding the mixture II in the step 3 into a wire drawing machine, wherein the gas pressure of the wire drawing machine is 0.8MPa, and the feeding speed is 150g/min, so as to obtain a fluffed mixture II;
step 5: pressing an electrode film on the fluffed mixture II obtained in the step 4 by using a high Wen Nianya roller, adjusting the temperature of a rolling machine to 150 ℃, and adjusting the rolling speed to 10m/min, and adjusting the electrode film to a target thickness through a plurality of rolling machines according to product requirements;
step 6: and (3) compounding the electrode film with the target thickness obtained in the step (5) with a metal current collector through a high-temperature roller, adjusting the temperature of a rolling machine to 150 ℃, and rolling at a speed of 10m/min to form the electrode plate with the sandwich structure of the electrode film/the metal current collector/the electrode film.
Example two
The embodiment relates to a preparation method of a low-yield gas dry electrode slice, which comprises the following steps:
step 1: adding active carbon and film forming agent dry powder into a mixer according to a mass ratio of 99:5, setting a mixing speed of 200r/min and mixing time to 3h to obtain a mixture I;
step 2: placing the mixture I obtained in the step 1 in a tank body with a valve, heating to 100 ℃, closing the valve (forming a sealed environment) after the temperature is uniform for 30min, and then cooling the tank body and powder to 15 ℃; introducing dry compressed air into the cooled tank body, wherein the flow rate of the dry air is 12m/s, and the introducing time of the dry air is 5s, so as to obtain the treated mixture I;
step 3: adding the mixture I obtained in the step 2, a conductive agent and a binder into a powder mixer according to a ratio of 80:10:10 for powder mixing, wherein the stirring speed of the mixer is 800r/min, and the powder mixing time is 2h, so as to obtain a mixture II;
step 4: adding the mixture II in the step 3 into a wire drawing machine, wherein the gas pressure of the wire drawing machine is 0.3MPa, and the feeding speed is 30g/min, so as to obtain a fluffed mixture II;
step 5: pressing an electrode film on the fluffed mixture II obtained in the step 4 by using a high Wen Nianya roller, adjusting the temperature of a rolling machine to 80 ℃, adjusting the rolling speed to 5m/min, and adjusting the electrode film to a target thickness through a plurality of rolling machines according to product requirements;
step 6: and (3) compounding the electrode film with the target thickness obtained in the step (5) with a metal current collector through a high-temperature roller, adjusting the temperature of a rolling machine to 80 ℃, and rolling at a speed of 5m/min to form the electrode plate with the sandwich structure of the electrode film/the metal current collector/the electrode film.
Example III
The embodiment relates to a preparation method of a low-yield gas dry electrode slice, which comprises the following steps:
step 1: adding active carbon and film forming agent dry powder into a mixer according to a mass ratio of 96:4, setting a mixing speed of 400r/min and a mixing time of 0.5h to obtain a mixture I;
step 2: placing the mixture I obtained in the step 1 in a tank body with a valve, heating to 200 ℃, closing the valve (forming a sealed environment) after the temperature is uniform for 30min, and then cooling the tank body and powder to 35 ℃; introducing dry compressed air into the cooled tank body, wherein the flow rate of the dry air is 18m/s, and the introducing time of the dry air is 2s, so as to obtain the treated mixture I;
step 3: adding the mixture I obtained in the step 2, a conductive agent and a binder into a powder mixer according to the proportion of 95:2.5:2.5 for powder mixing, wherein the stirring speed of the mixer is 1200r/min, and the powder mixing time is 2h, so as to obtain a mixture II;
step 4: adding the mixture II in the step 3 into a wire drawing machine, wherein the gas pressure of the wire drawing machine is 0.8MPa, and the feeding speed is 300g/min, so as to obtain a fluffed mixture II;
step 5: pressing an electrode film on the fluffed mixture II obtained in the step 4 by using a high Wen Nianya roller, adjusting the temperature of a rolling machine to 250 ℃, adjusting the rolling speed to 20m/min, and adjusting the electrode film to a target thickness through a plurality of rolling machines according to product requirements;
step 6: and (3) compounding the electrode film with the target thickness obtained in the step (5) with a metal current collector through a high-temperature roller, adjusting the temperature of a rolling machine to 250 ℃, and forming the electrode plate with the sandwich structure of the electrode film/the metal current collector/the electrode film at the rolling speed of 20 m/min.
Embodiment four: the mixture I is not subjected to heating and exhausting treatment and cooling treatment
Step 1: adding active carbon and film forming agent dry powder into a mixer according to a mass ratio of 99:1, setting a mixing speed of 300r/min, and mixing for 2 hours to obtain a mixture I;
step 2: adding the mixture I obtained in the step 1, a conductive agent and a binder into a powder mixer according to the proportion of 90:5:5 for powder mixing, wherein the stirring speed of the mixer is 1000r/min, and the powder mixing time is 3h, so as to obtain a mixture II;
step 3: adding the mixture II obtained in the step 2 into a wire drawing machine, wherein the gas pressure of the wire drawing machine is 0.8MPa, and the feeding speed is 150g/min, so as to obtain a fluffed mixture II;
step 4: pressing an electrode film on the fluffy mixture II obtained in the step 3 by using a high Wen Nianya roller, adjusting the temperature of a rolling machine to 150 ℃, adjusting the rolling speed to 10m/min, and adjusting the thickness to a required thickness through a plurality of rolling machines according to the product requirement to obtain the electrode film with the target thickness;
step 5: and (3) compounding the electrode film with the target thickness obtained in the step (4) with a metal current collector through a high-temperature roller, adjusting the temperature of a rolling machine to 150 ℃, and rolling at a speed of 10m/min to form the electrode plate with the sandwich structure of the electrode film/the metal current collector/the electrode film.
Fifth embodiment: without using film-forming agent dry powder
Step 1: adding the activated carbon, the conductive agent and the adhesive into a powder mixer according to the proportion of 90:5:5 for powder mixing, wherein the stirring speed of the mixer is 1000r/min, and the powder mixing time is 3h, so as to obtain a mixed material;
step 2: adding the mixed material obtained in the step 1 into a wire drawing machine, wherein the gas pressure of the wire drawing machine is 0.8MPa, and the feeding speed is 150g/min, so as to obtain a fluffy mixed material;
step 3: pressing an electrode film on the fluffy mixed material obtained in the step 2 by using a high Wen Nianya roller, adjusting the temperature of a rolling machine to 150 ℃, adjusting the rolling speed to 10m/min, and adjusting the thickness to a required thickness through a plurality of rolling machines according to the product requirement to obtain the electrode film with the target thickness;
step 4: and (3) compounding the electrode film with the target thickness prepared in the step (3) with a metal current collector through a high-temperature roller, adjusting the temperature of a rolling machine to 150 ℃, and rolling at a speed of 10m/min to form the electrode plate with the sandwich structure of the electrode film/the metal current collector/the electrode film.
Test examples
And preparing the electrode plates prepared in the first to fifth embodiments into super capacitors with the same specification, and performing gas production test, internal resistance increase performance test and pole piece capacity attenuation performance test.
(1) The specific test conditions for the gas production test are as follows: and installing a built-in gas pressure sensor at a liquid injection port of the capacitor, placing the capacitor in a 65 ℃ oven, charging the capacitor to 2.7V by adopting a constant current of 100A current after the temperature is uniform, then floating charging at a constant voltage, and recording the internal pressure change of the capacitor at different times.
(2) Specific test conditions for the internal resistance increase performance test are: firstly testing the initial internal resistance of a capacitor, then placing the capacitor in a 65 ℃ oven, charging to 2.7V by adopting 100A current constant current after the temperature is uniform, then floating charging, respectively testing the internal resistance of the capacitor at 2/12/24 hours, and then testing the internal resistance of the capacitor after each floating charging for 24 hours and recording.
(3) The specific test conditions for the pole piece capacity attenuation performance test are as follows: the initial capacity of the capacitor is tested firstly, then the capacitor is placed in a 65 ℃ oven, after the temperature is uniform, the capacitor is charged to 2.7V by adopting a constant current of 100A, then floating charge is carried out, the capacity of the capacitor is tested at 2/12/24 hours respectively, and then the capacity of the capacitor is tested after each floating charge for 24 hours and recorded.
Wherein, FIG. 1 is a comparison of SEM of the first embodiment and the fifth embodiment of the present invention, wherein (a) the SEM of the mixture I of the first embodiment and (b) the SEM of the activated carbon; as can be seen from fig. 1 (a), the activated carbon in the mixture i treated according to the first embodiment of the present invention has a film forming agent on the outer surface, but also in some of the large pores.
FIG. 2 is a graph showing comparison of the results of gas production according to embodiments one to five of the present invention; as can be seen from fig. 2, the super capacitor manufactured by using the electrode sheet obtained in the first embodiment has a pressure of 393KPa of generated gas within 700 hours under a constant pressure of 2.7V floating charge condition at 65 ℃; the super capacitor manufactured by the electrode plate obtained in the second embodiment has the pressure of the generated gas of 573KPa within 700 h; the super capacitor manufactured by the electrode plate obtained in the third embodiment has the pressure of generated gas within 700h of 492KPa; the super capacitor prepared by the electrode plate obtained in the fourth embodiment has the pressure of the generated gas of 696KPa within 700 h; the supercapacitor produced by using the electrode sheet obtained in example five had a pressure of 1114KPa of generated gas within 700 hours. Therefore, compared with the super capacitor prepared by the first and third embodiments, the fourth embodiment only adding the film forming agent and the fifth embodiment not adding the film forming agent can effectively reduce the gas yield of the super capacitor.
Wherein, FIG. 3 is a graph showing the capacity fade performance of the pole pieces of the first to fifth embodiments of the present invention; as can be seen from fig. 3, the capacity retention rate of the supercapacitor manufactured by using the electrode sheet obtained in the first embodiment is 87.3% in 1000 hours under the condition of constant voltage of 2.7V at 65 ℃; under the condition of constant voltage of 2.7V at 65 ℃, the capacity retention rate of the supercapacitor prepared by adopting the electrode plate obtained in the second embodiment is 84.9% in 1000 hours; under the condition of constant voltage of 2.7V at 65 ℃, the capacity retention rate of the supercapacitor prepared by adopting the electrode sheet obtained in the third embodiment is 86.5% within 1000 hours; under the condition of constant voltage of 2.7V at 65 ℃, the capacity retention rate of the supercapacitor prepared by adopting the electrode plate obtained in the fourth embodiment is 77.1% in 1000 hours; the capacity retention rate of the supercapacitor prepared by adopting the electrode sheet obtained in the fifth embodiment is 72.1% in 1000h under the condition of constant voltage of 2.7V at 65 ℃. FIG. 4 is a graph showing the performance of increasing the internal resistance of the pole pieces according to the first to fifth embodiments of the present invention; as can be seen from fig. 4, under the condition of constant voltage of 2.7V at 65 ℃, the internal resistance increase rate of the supercapacitor manufactured by using the electrode sheet obtained in the first embodiment is 125.5% within 1000 hours; under the condition of constant voltage of 2.7V at 65 ℃, the internal resistance increase rate of the supercapacitor prepared by adopting the electrode plate obtained in the second embodiment is 130.2% within 1000 hours; under the condition of constant voltage of 2.7V at 65 ℃, the internal resistance increase rate of the supercapacitor prepared by adopting the electrode sheet obtained in the third embodiment is 131.6% within 1000 hours; under the condition of constant voltage of 2.7V at 65 ℃, the internal resistance increase rate of the supercapacitor prepared by adopting the electrode plate obtained in the fourth embodiment is 157.7% within 1000 hours; under the condition of constant voltage of 2.7V at 65 ℃, the internal resistance increase rate of the supercapacitor prepared by adopting the electrode plate obtained in the fifth embodiment is 170.1% within 1000 hours. Compared with the fourth embodiment with only the film forming agent and the fifth embodiment without the film forming agent, the super capacitor prepared by the first and third embodiments of the invention can effectively prolong the service life of the capacitor and reduce the internal resistance increasing rate of the capacitor.
In summary, the film forming agent is added to prevent the electrolyte from reacting with the active site of the active material, and the film forming agent is placed in the inner hole of the active carbon by utilizing the characteristic of the active material of high adsorption capacity to gas molecules, so that the purposes of preventing the surface active site of the active material from further reacting with the electrolyte and reducing the gas production of the pole piece are achieved, the service life of the supercapacitor is effectively prolonged, and the cost of the supercapacitor is reduced.
In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.
While embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the invention, and that variations, modifications, alternatives and variations may be made to the above embodiments by one of ordinary skill in the art within the scope of the invention.
Claims (9)
1. The preparation method of the low-gas-yield dry electrode slice is characterized by comprising the following steps of:
step 1: mixing for the first time according to the mass ratio of the active material to the film forming agent dry powder of 95:5-99:1, wherein the stirring speed of the first mixing is 200-400 r/min, and the stirring time is 0.5-3 h, so as to obtain a mixture I;
step 2: heating the mixture I to 100-200 ℃ for exhaust treatment, cooling the mixture I after exhaust treatment to 0-35 ℃ in a sealing state after the temperature is kept constant for at least 30min, and introducing dry gas into the mixture I after cooling in the sealing state, wherein the flow rate of the dry gas is 10-20 m/s, and the introducing time of the dry gas is 1-6 s, so as to obtain the mixture I after treatment;
step 3: mixing the treated mixture I with a conductive agent and a binder for the second time according to the mass ratio of 80:10:10-95:2.5:2.5, wherein the stirring speed of the second mixing is 800-1200 r/min, and the stirring time is 2-4 h, so as to obtain a mixture II;
step 4: carrying out fluffing treatment on the mixture II under the condition that the gas pressure is 0.3-0.8 Mpa and the feeding speed is 30-300 g/min to obtain a fluffed mixture II;
step 5: rolling the fluffed mixture II into an electrode film, wherein the temperature of the rolled electrode film is 80-250 ℃, and the speed is less than or equal to 20m/min, so as to obtain the electrode film with target thickness;
step 6: sequentially carrying out three-layer rolling compounding on the electrode film, the metal current collector and the electrode film with target thickness, wherein the temperature of the three-layer rolling compounding is 80-250 ℃ and the speed is less than or equal to 20m/min, so as to form an electrode sheet with the electrode film/the metal current collector/the electrode film;
the active material comprises any one or a mixture of at least two of active carbon, nano carbon fiber, glass carbon, carbon aerogel and carbon nano tube; the film forming agent dry powder comprises any one or a mixture of at least two of lithium carbonate, lithium difluorophosphate, lithium bisoxalato borate and sodium carboxymethyl cellulose.
2. The method for preparing the low-yield gas dry method electrode slice according to claim 1, wherein,
in the step 1, the mass ratio of the active material to the film forming agent dry powder is 96:4-99: 1, carrying out primary mixing, wherein the stirring speed of the primary mixing is 250-350 r/min, and the stirring time is 1-2 h, so as to obtain a mixture I.
3. The method for preparing the low-yield gas dry method electrode slice according to claim 1, wherein,
in the step 2, the mixture I is heated to 120-180 ℃ for exhaust treatment, after the temperature is kept constant for at least 30min, the temperature of the mixture I after the exhaust treatment is reduced to 0-25 ℃ in a sealing state, and dry gas is introduced into the mixture I after the temperature reduction in the sealing state, wherein the flow rate of the dry gas is 12-18 m/s, and the time for introducing the dry gas is 2-4 s, so that the mixture I after the treatment is obtained.
4. A method for preparing a low-gas-yield dry electrode sheet according to any one of claims 1 to 3, wherein,
the drying gas in the step 2 is any one or a mixture of at least two of compressed air, nitrogen and helium.
5. The method for preparing the low-yield gas dry method electrode slice according to claim 1, wherein,
in the step 3, the treated mixture I, the conductive agent and the binder are mixed for the second time according to the mass ratio of 85:5:10-90:5:5, the stirring speed of the second mixing is 900-1100 r/min, and the stirring time is 2.5-3.5 h, so that a mixture II is obtained;
in the step 4, the mixture II is subjected to fluffing treatment under the condition that the gas pressure is 0.4-0.7 Mpa and the feeding speed is 100-200 g/min, so as to obtain the fluffed mixture II.
6. The method for preparing the low-yield gas dry method electrode slice according to claim 1, wherein,
in the step 5, the fluffy mixture II is rolled into an electrode film, the temperature of the rolled electrode film is 100-200 ℃, and the speed is less than or equal to 15m/min, so that the electrode film with the target thickness is obtained;
in the step 6, the electrode film and the metal current collector with target thickness are sequentially laminated and compounded by three layers of the electrode film, the metal current collector and the electrode film, wherein the temperature of the laminated and compounded three layers is 100-200 ℃, and the speed is less than or equal to 15m/min, so that the electrode plate with a sandwich structure of the electrode film/the metal current collector/the electrode film is formed.
7. The method for preparing the low-yield gas dry electrode slice according to any one of claims 1 to 3, 5 and 6, wherein,
the conductive agent comprises any one or a mixture of at least two of metal powder, acetylene black, ketjen black, furnace black, conductive graphite, carbon nanotubes, carbon fibers and graphene;
the binder comprises any one or a mixture of at least two of polytetrafluoroethylene, polyvinylidene fluoride and polyvinyl alcohol;
the metal current collector is copper foil or aluminum foil.
8. A low-gas-production dry electrode sheet, characterized by being prepared by the preparation method as claimed in any one of claims 1 to 7.
9. A supercapacitor comprising a low-gassing dry electrode sheet according to claim 8.
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| JP2007273508A (en) * | 2006-03-30 | 2007-10-18 | Mitsubishi Electric Corp | Process for producing coating type electrode sheet for electric double layer capacitor |
| JP2007302512A (en) * | 2006-05-11 | 2007-11-22 | Nippon Oil Corp | Active carbon and electric double layer capacitor using the same |
| CN106654177A (en) * | 2016-11-29 | 2017-05-10 | 宁波中车新能源科技有限公司 | Method for preparing battery capacitor composite electrode by dry method |
| CN115440931A (en) * | 2022-09-13 | 2022-12-06 | 季华实验室 | Lithium ion battery electrode plate and preparation method thereof |
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| JP2007273508A (en) * | 2006-03-30 | 2007-10-18 | Mitsubishi Electric Corp | Process for producing coating type electrode sheet for electric double layer capacitor |
| JP2007302512A (en) * | 2006-05-11 | 2007-11-22 | Nippon Oil Corp | Active carbon and electric double layer capacitor using the same |
| CN106654177A (en) * | 2016-11-29 | 2017-05-10 | 宁波中车新能源科技有限公司 | Method for preparing battery capacitor composite electrode by dry method |
| CN115440931A (en) * | 2022-09-13 | 2022-12-06 | 季华实验室 | Lithium ion battery electrode plate and preparation method thereof |
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