A dry-process super peel strength electrode and a method for manufacturing the same, and an electrode powder stirring device

Abstract

The application belongs to the technical field of battery materials, and particularly relates to a dry-method super-strong peeling force electrode preparation method and electrode powder preparation equipment thereof. The preparation method forms a three-dimensional network bonding structure of electrode powder (active material, conductive agent and binder) through a three-step process of "powder pretreatment - layered electrode compaction - in-situ activation", has a layered electrode structure of "current collector - hydrogen bond thin self-supporting electrode film - ordinary thick self-supporting electrode film", and significantly improves the peeling strength of the electrode and the current collector. The matching preparation equipment can realize efficient mixing and dispersion of the electrode powder and control the mixing temperature in the sealed reaction kettle through high-speed shearing and heating devices, and can prepare electrode powder with excellent dispersity and strong interface bonding force, and has high efficiency and stability.

Description

Technical Field

[0001] This invention belongs to the field of battery material technology, specifically relating to a dry-process ultra-strong peeling force electrode and its preparation method, as well as an electrode powder stirring equipment. Background Technology

[0002] Traditional energy storage battery electrodes mostly employ a wet coating process, which requires solvents such as N-methylpyrrolidone (NMP) and water to dissolve the binder. The active material, conductive agent, and binder are then mixed to form a slurry, which is coated onto the current collector and subsequently dried at high temperature to remove the solvent. However, the wet process suffers from several drawbacks: solvent evaporation pollutes the environment; residual solvents can affect electrode performance; the high-temperature drying stage consumes more than 30% of the total energy consumption in battery production; and residual solvents within the film can trigger side reactions in the electrolyte. Furthermore, the adhesion between the electrode film and the current collector relies on the physical adsorption of the binder, resulting in low peel strength, making it unsuitable for the harsh operating conditions of high-rate charging and discharging and long-term vibration in energy storage batteries. The complex process also limits production efficiency, making it difficult to meet the demands of large-scale mass production.

[0003] Dry electrode fabrication technology has become a research hotspot in the field of energy storage batteries due to its solvent-free, low-energy, and environmentally friendly characteristics, as well as its ability to significantly reduce production energy consumption and shorten process flow. However, existing dry technologies still have core bottlenecks, generally suffering from insufficient electrode peeling force, poor structural stability, and difficulty in controlling mass production consistency. Current dry processes often achieve powder forming and current collector composite through a single compaction step, which easily leads to uneven binder dispersion and insufficient fibrillation, resulting in weak interfacial bonding between the electrode and current collector. Under the volume deformation, high temperature, and vibration conditions of charge-discharge cycles, this easily leads to film delamination and material shedding failure. Therefore, developing a dry electrode fabrication method that combines high interfacial peeling force, high batch consistency, and low cost, breaking through existing technological bottlenecks, is of great significance for promoting the large-scale industrialization of energy storage batteries. Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to provide a dry-process ultra-strong peeling force electrode and its preparation method, as well as an electrode powder stirring device. The electrode sheet prepared by this method has a three-dimensional network bonding structure formed by a layered electrode structure of "current collector-hydrogen bonded thin self-supporting electrode film-ordinary thick self-supporting electrode film". The peeling strength between the electrode and the current collector is high, and the battery composed of it has excellent rate performance and capacity retention. The supporting preparation equipment is equipped with a dual-blade high-speed shearing and heating device, which can prepare electrode powder with excellent dispersibility and strong interfacial bonding, combining high efficiency and stability.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: On one hand, the method for preparing a dry-process ultra-strong peeling force electrode provided by the present invention includes the following steps: Step 1: Surface modification of the active material is performed by plasma treatment to obtain surface-modified active material; the surface-modified active material, conductive agent, and polyacrylic acid (PAA) binder are stirred evenly in an electrode powder stirring device to obtain PAA-containing composite powder; the surface-modified active material, conductive agent, and polytetrafluoroethylene (PTFE) binder are stirred evenly in an electrode powder stirring device to obtain PTFE-containing composite powder. Step 2: The PAA-containing composite powder and the PTFE-containing composite powder are respectively fed into a roller press for pre-pressing to form a PAA-containing self-supporting electrode film and a PTFE-containing self-supporting electrode film. The current collector, the PAA-containing self-supporting electrode film and the PTFE-containing self-supporting electrode film are stacked in the order of stacking and then fed into the roller press for main pressing to form the electrode film layer. Step 3: The electrode film is sent into an activation furnace. In an inert atmosphere, it is heated to achieve in-situ cross-linking of the binder and interface activation. After cooling, a dry-process ultra-strong peeling electrode is obtained.

[0006] In step 1, preferably, the plasma treatment power is 100-300 W, and the treatment time is 5-15 min. Before pretreatment, the active material undergoes surface modification via plasma treatment to introduce polar groups, thereby improving the interfacial compatibility between the active material and the binder.

[0007] In step 1, preferably, the mass ratio of surface-modified active material, conductive agent, and polyacrylic acid binder in the PAA-containing composite powder is 20~24:1:2~3; and the mass ratio of surface-modified active material, conductive agent, and polytetrafluoroethylene binder in the PTFE-containing composite powder is 29~32:1:0.8~1.2. The PAA-containing composite powder contains a higher proportion of conductive agent, which, on the one hand, can form additional hydrogen bonds with the hydroxyl groups of the current collector surface oxide layer through polar groups, increasing the interfacial bonding sites; on the other hand, it can improve the interfacial wettability between the electrode film and the current collector, increase the effective contact area, and significantly improve the electrode peel strength.

[0008] In step 1, preferably, the active material is one or more of battery-grade layered oxides, hard carbon, and graphite. Examples of layered oxides include NaCoO2 and NaFe. 0.5 Mn 0.5 O2, LiCoO2, LiFe 0.5 Mn 0.5 One or more of O2.

[0009] In step 1, preferably, the conductive agent is one or more of superconducting carbon black, acetylene black, Ketjen black, carbon nanofibers, graphene, and graphene oxide.

[0010] In step 1, preferably, the surface-modified active material and conductive agent are first added to the electrode powder stirring device and stirred for 10-40 minutes. Then, the mixture is heated to 70-95°C, and a polyacrylic acid binder or a polytetrafluoroethylene binder is added. The temperature is maintained, and stirring continues for 5-30 minutes, resulting in PAA-containing composite powder or PTFE-containing composite powder. High-speed stirring achieves uniform dispersion of the active material, conductive agent, and binder, while simultaneously fiberizing the binder. This invention employs a step-by-step feeding process. Without the interference of binder viscosity, high-speed stirring for 10-40 minutes first thoroughly disperses and uniformly mixes the surface-modified active material and conductive agent, forming a stable low-resistance electronic conduction path between the conductive particles. Then, the binder is added. The binder only fills the gaps between the composite units and does not disrupt the already formed conductive contact, significantly reducing the electrode body impedance and contact impedance, and significantly improving the electrode rate performance.

[0011] In step 1, preferably, the rotation speed of the electrode powder stirring device is 3000~12000 r / min.

[0012] In step 1, preferably, the working atmosphere of the electrode powder stirring device is an inert atmosphere. The inert gas protection prevents powder oxidation. In this document, the inert atmosphere is nitrogen and / or argon.

[0013] The electrode powder stirring device can be a conventional mixer suitable for dry electrode powder stirring. Preferably, a special mixer further researched and improved by the inventor is used, which specifically includes: a base support, a rocker arm, a column guide rail, a motor box, a stirring assembly, a reaction vessel, a heating device, and anti-slip feet; The base support has anti-slip feet at the bottom and an integrated heating device mounting position at the top for fixing the heating device; the column guide rail is vertically fixed to one side of the base support, and a rocker arm is provided at the top of the column guide rail; the motor box is slidably connected to the column guide rail, and the motor box can be driven to move up and down along the column guide rail by rotating the rocker arm; the output end of the motor box is connected to the stirring assembly, and the stirring assembly includes at least two blades with different structures; the reaction vessel is located below the stirring assembly, and the top of the reaction vessel is sealed to the bottom of the motor box by a sealing ring, and the heating device is nested at the bottom of the reaction vessel.

[0014] Preferably, the surface of the column guide rail is marked with scale markings.

[0015] Preferably, the stroke range of the motor housing is 50~200 mm.

[0016] Preferably, the motor housing has a built-in speed-regulating motor with an output speed range of 0~15000 r / min, which can achieve stepless speed regulation.

[0017] Preferably, the stirring assembly includes at least two blades with different structures, including a first blade with a gear-shaped structure and a second blade with a spiral structure.

[0018] Preferably, the cutting head of the tool extends into the inner wall area of ​​the reactor, and the height of the second tool is adjustable from 0 to 5 mm.

[0019] In step 2, preferably, the pre-compression pressure is 5~10 MPa, the main pressure is 25~50 MPa, and the compaction temperature is 80~100℃.

[0020] In step 2, preferably, the thickness of the PAA-containing self-supporting electrode film is thinner than that of the PTFE-containing self-supporting electrode film, with the PAA-containing self-supporting electrode film having a thickness of 5-30 μm and the PTFE-containing self-supporting electrode film having a thickness of 45-100 μm. This invention employs a thickness gradient design between the PAA-containing and PTFE-containing self-supporting electrode films. The thin PAA film exhibits excellent adhesion to the current collector, and its strong hydrogen bonding maximizes interfacial bonding while simultaneously constructing a low-impedance electronic conduction transition channel, eliminating abrupt changes in contact impedance between the thick electrode and the current collector. The thick PTFE film, serving as the electrode's main body layer, utilizes the elasticity of its PTFE fibers to buffer electrode volume expansion during charging and discharging and maintain electrode cohesion. The low binder content and greater thickness ensure a higher active material loading, increasing the overall electrode energy density.

[0021] Preferably, the current collector is roughened before use to control its surface roughness Ra to be between 0.5 and 2.0 μm. Roughening enhances the mechanical adhesion between the current collector and the electrode film. The roughening method is not particularly limited and can include sandblasting, electrochemical roughening, etc. The current collector is, for example, aluminum foil.

[0022] In step 3, the heating temperature is 150~200℃, the heating rate is 5~10℃ / min, and the holding time is 40~60min. The compacted electrode film is further heated and activated. During the holding process, the binder undergoes a cross-linking reaction to form a three-dimensional network structure, which firmly encapsulates and bonds the active material and conductive agent to the surface of the current collector. At the same time, the micro-nano structure formed by the roughening treatment of the current collector forms a mechanical bond with the electrode film, further improving the peeling force.

[0023] On the other hand, the present invention provides an electrode powder stirring device for preparing dry-process ultra-strong peeling force electrodes, comprising: a base support, a rocker arm, a column guide rail, a motor box, a stirring assembly, a reaction vessel, a heating device, and anti-slip feet; The base support has anti-slip feet at the bottom and an integrated heating device mounting position at the top for fixing the heating device; the column guide rail is vertically fixed to one side of the base support, and a rocker arm is provided at the top of the column guide rail; the motor box is slidably connected to the column guide rail, and the motor box can be driven to move up and down along the column guide rail by rotating the rocker arm; the output end of the motor box is connected to the stirring assembly, and the stirring assembly includes at least two blades with different structures; the reaction vessel is located below the stirring assembly, and the top of the reaction vessel is sealed to the bottom of the motor box by a sealing ring, and the heating device is nested at the bottom of the reaction vessel.

[0024] Compared with the prior art, the present invention has the following beneficial effects: 1. The gradient layered structure design of “thin PAA hydrogen bond interface layer + thick PTFE main body layer” is adopted. The interface layer provides strong adhesion, and the main body layer achieves high active material loading through low binder ratio and thick layer design, which significantly improves electrode energy density while ensuring adhesion. 2. The electrode film is activated in situ. During the medium-temperature heat preservation process, the binder undergoes a cross-linking reaction to form a three-dimensional network structure, which firmly encapsulates and bonds the active material and conductive agent to the surface of the current collector, effectively avoiding powder shedding and delamination problems, and significantly improving the electrode peeling ability. 3. The dry preparation process leaves no solvent residue, resulting in low electrode porosity, increased ion migration rate, positive electrode peel strength ≥12 N / cm, and peel force fluctuation ±0.2 N / cm; 4. No solvent drying step is required, which reduces energy consumption compared to wet processes. There is no waste gas or waste liquid emission, which meets the requirements of green production. 5. With dedicated preparation equipment, continuous production of electrodes can be achieved, with a production efficiency of ≥5 m / min, product thickness consistency of ±0.08mm, and capacity retention rate of ≥97% after 400 long-term cycles, which can meet the mass production needs of large-scale energy storage and power batteries. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of an electrode powder stirring device; The components include: 1. rocker arm; 2. column guide rail; 3. first cutting tool; 4. motor box; 5. second cutting tool; 6. sealing ring; 7. reaction vessel; 8. heating device; and 9. anti-slip feet.

[0026] Figure 2 The NaFe prepared in Example 2 0.5 Mn 0.5 O2 electrode peel force test curve. Detailed Implementation

[0027] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0028] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0029] The directional terms such as above, below, left, right, front, and back used in this application are based on the positional relationships shown in the attached drawings. Different attached drawings may result in different positional relationships, therefore they should not be interpreted as limitations on the scope of protection.

[0030] In this application, the terms "installation," "connection," "interlocking," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, an integral connection, a mechanical connection, an electrical connection or a connection that allows communication between components, a direct connection, or an indirect connection through an intermediate medium. They can also refer to the internal connection between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0031] The electrode powder stirring device provided by this invention is as follows: Figure 1 As shown, it includes: a base support, a rocker arm 1, a column guide rail 2, a motor housing 4, a stirring assembly, a reaction vessel 7, a heating device 8, and anti-slip feet 9. The base support has anti-slip feet 9 at the bottom to ensure the stability of the equipment during operation, and the upper part of the base support integrates a mounting position for the heating device 8 for fixing the heating device 8.

[0032] The column guide rail 2 is vertically fixed to one side of the base bracket. The top of the column guide rail 2 is equipped with a rocker arm 1 for driving the motor box 4 to rise and fall. The surface of the column guide rail 2 is marked with scale marks. The motor box 4 is slidably connected to the column guide rail 2. By rotating the top rocker arm 1, the motor box 4 can be driven to move up and down along the column guide rail 2. The stroke range is 50~200 mm, so as to achieve precise docking / separation of the stirring component and the reaction vessel 7.

[0033] The motor housing 4 has a built-in speed-regulating motor with an output speed range of 0~15000 r / min, which can achieve stepless speed regulation. The output end of the motor housing 4 is connected to the stirring assembly, which includes at least two blades with different structures (first blade 3 and second blade 5). The first blade 3 has a gear-type structure, and the second blade 5 has a spiral structure. The blade tip extends to the inner wall area of ​​the reactor 7. The height of the second blade 5 is adjustable from 0 to 5 mm to adapt to different powder filling amounts. The staggered distribution of the two blades can perform a synergistic shearing and dispersion effect on the electrode powder (active material, conductive agent, binder) in the reactor, avoiding powder agglomeration.

[0034] The reaction vessel 7 is located below the stirring assembly. A sealing ring 6, made of fluororubber, is provided between the reaction vessel 7 and the motor housing 4, with its inner diameter fitting a clearance fit with the outer diameter of the reaction vessel's opening. The heating device 8 is located outside the reaction vessel 6 and is fixedly connected to the base support. The heating device 8 is a wraparound electric heating sleeve with a temperature adjustment range of 10℃ to 150℃. The reaction vessel 7 is a cylindrical sealed cavity, with its top sealed to the bottom of the motor housing 4 via the sealing ring 6, achieving a solvent-free and impurity-free environment during the powder mixing process. The heating device 8 is nested at the bottom of the reaction vessel 7, and the heating device 8 has a built-in temperature sensor that can provide real-time feedback and control the temperature inside the reaction vessel.

[0035] Example 1 In this embodiment, a positive electrode sheet with NaCoO2 as the active material is prepared. The specific steps are as follows: Step 1: Surface modification of the active material NaCoO2 was performed by plasma treatment (power 200 W, treatment time 10 min) to obtain surface-modified NaCoO2; 88 g of surface-modified NaCoO2 and 4 g of conductive carbon black were placed in... Figure 1 In the electrode powder stirring apparatus shown, nitrogen gas was introduced for protection, and the mixture was stirred at 6000 r / min for 20 min. The mixture was then heated to 80℃, and 8 g of polyacrylic acid binder was added. The mixture was stirred at 6000 r / min for 20 min to obtain a uniformly dispersed PAA-containing composite powder. 94 g of surface-modified NaCoO2 and 3 g of conductive carbon black were then added to the apparatus as shown. Figure 1 In the electrode powder stirring device shown, nitrogen gas was introduced for protection, and the mixture was stirred at 6000 r / min for 20 min. The mixture was then heated to 80℃, and 3 g of polytetrafluoroethylene binder was added. The mixture was stirred at 6000 r / min for 20 min to obtain a uniformly dispersed PAA-containing composite powder.

[0036] Step 2: The PAA-containing composite powder and the PTFE-containing composite powder are respectively fed into a roller press for pre-pressing (pre-pressing pressure 10 MPa, compaction temperature 100℃) to form a PAA-containing self-supporting electrode film with a thickness of 10 μm and a PTFE-containing self-supporting electrode film with a thickness of 55 μm; the current collector aluminum foil is roughened before use so that the surface roughness Ra of the current collector is controlled within the range of 0.5~2.0 μm; the aluminum foil, PAA-containing self-supporting electrode film and PTFE-containing self-supporting electrode film are stacked together in the order of current collector aluminum foil, PAA-containing self-supporting electrode film and PTFE-containing self-supporting electrode film, and fed into the roller press for main pressing (main pressing pressure 40 MPa, compaction temperature 100℃) to form the electrode film layer.

[0037] Step 3: The electrode film is sent into the activation furnace, argon gas (purity 99.99%) is introduced, the temperature is increased to 150 ℃ at 8 ℃ / min, held for 45 min, cooled and then wound up to obtain NaCoO2 positive electrode sheet.

[0038] Example 1 was subjected to a 180° peel test at a speed of 50 mm / min, and the peel strength was 12.5 N / cm.

[0039] After assembling the electrodes into a sodium half-cell, the initial discharge capacity at 0.1 C rate was 120 mAh / g, and the capacity retention rate was 99% after 400 cycles.

[0040] Using the matching equipment, 10 m electrodes can be produced continuously with thickness fluctuations within ±0.08 mm and peel force fluctuations within ±0.2 N / cm.

[0041] Example 2 The difference between Example 2 and Example 1 is that the active substance in Example 2 is NaFe. 0.5 Mn 0.5 O2, the other steps are the same as in Example 1.

[0042] A 180° peel test was performed on Example 2, and the electrode peel force test curve of this example was recorded on [date missing]. Figure 2 The test speed was 50 mm / min, and the peel strength was 11.9 N / cm.

[0043] After assembling the electrodes into a sodium half-cell, the initial discharge capacity at 0.1 C rate was 165 mAh / g, and the capacity retention rate was 99% after 400 cycles.

[0044] Using the matching equipment, 10 m electrodes can be produced continuously with thickness fluctuations within ±0.08 mm and peel force fluctuations within ±0.3 N / cm.

[0045] Example 3 The difference between Example 3 and Example 1 is that the active material in Example 3 is hard carbon, while the other steps are the same as in Example 1.

[0046] A 180° peel test was performed on this embodiment, and the average peel strength was 9.4 N / cm. After assembling the electrodes into a sodium half-cell, the initial sodium intercalation capacity at 0.1 C rate was 200 mAh / g, and the capacity retention rate was 97% after 400 cycles.

[0047] Example 4 The difference between Example 4 and Example 1 is that the PAA self-supporting electrode film is 55 μm thick and the PTFE self-supporting electrode film is 10 μm thick. The other steps are the same as in Example 1.

[0048] A 180° peel test was performed on this embodiment, and the average peel strength was 11.4 N / cm. After assembling the electrodes into a sodium half-cell, the initial sodium intercalation capacity at 0.1 C rate was 112 mAh / g, and the capacity retention rate was 95% after 400 cycles.

[0049] Example 5 The difference between Example 5 and Example 1 is that the PAA self-supporting electrode film is 30 μm thick and the PTFE self-supporting electrode film is 35 μm thick. The other steps are the same as in Example 1.

[0050] A 180° peel test was performed on this embodiment, and the average peel strength was 10.2 N / cm. After assembling the electrodes into a sodium half-cell, the initial sodium intercalation capacity at 0.1 C rate was 105.2 mAh / g, and the capacity retention rate was 92% after 400 cycles.

[0051] Example 6 The difference between Example 6 and Example 1 is that in the preparation of PAA-containing composite powder, 94g of modified NaCoO2, 2g of conductive carbon black, and 4g of polyacrylic acid binder were used, while the other steps were the same as in Example 1.

[0052] A 180° peel test was performed on this embodiment, and the average peel strength was 8.7 N / cm. After assembling the electrodes into a sodium half-cell, the initial sodium intercalation capacity at 0.1 C rate was 110 mAh / g, and the capacity retention rate was 99% after 400 cycles.

[0053] Example 3 replaced the negative electrode active material with hard carbon, achieving a peel strength of 9.4 N / cm. However, this was not well-suited to the interface bonding design optimized for layered oxide cathode systems in this invention, and the synergistic strengthening effect of this invention could not be fully realized. Examples 4 and 5 had thicker PAA-containing self-supporting electrode films, but the thickened PAA film significantly encroached on the loading space of the high-capacity active material, resulting in a decrease in the initial discharge capacity at 0.1 C to 112 mAh / g and 105.2 mAh / g, respectively, and a decrease in peel strength to 11.4 N / cm and 10.2 N / cm, respectively. At the same time, the PTFE main film thickness in Example 5 was insufficient, and the elastic network formed by PTFE fiberization could not buffer the volume deformation of the active material during the charge and discharge process. Ultimately, the capacity retention rate after 400 cycles was only 92%, and the cycle stability was significantly deteriorated. Example 6 reduced the proportion of conductive agent in the PAA-containing composite powder. The low content of conductive agent could not form a continuous low-impedance electronic conduction path in the PAA interface layer, directly leading to a decrease in the uniformity of electrode interface bonding and rate performance.

[0054] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that Comparative Example 1 only prepared a 65 μm thick PAA-containing self-supporting electrode film, by stacking the current collector aluminum foil and the PAA-containing self-supporting electrode film together to form the electrode film layer. The other steps are the same as in Example 1.

[0055] A 180° peel test was performed on this comparative example, and the average peel strength was 18 N / cm. After assembling the electrodes into a sodium half-cell, the initial sodium intercalation capacity at 0.1 C rate was 113 mAh / g, and the capacity retention rate was 93% after 400 cycles.

[0056] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that Comparative Example 2 only prepared a 65 μm thick PTFE-containing self-supporting electrode film, by stacking the current collector aluminum foil and the PTFE-containing self-supporting electrode film together to form the electrode film layer. The other steps are the same as in Example 1.

[0057] A 180° peel test was performed on this comparative example, and the average peel strength was 8.2 N / cm. After assembling the electrodes into a sodium half-cell, the initial sodium intercalation capacity at 0.1 C rate was 118 mAh / g, and the capacity retention rate was 97% after 400 cycles.

[0058] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that the current collector, PTFE-containing self-supporting electrode film, and PAA-containing self-supporting electrode film are rolled and stacked in the order of roll forming. The thickness of both is not changed, and the other steps are the same as in Example 1.

[0059] A 180° peel test was performed on this comparative example, and the average peel strength was 9 N / cm. After assembling the electrodes into a sodium half-cell, the initial sodium intercalation capacity at 0.1 C rate was 99 mAh / g, and the capacity retention rate was 89% after 400 cycles.

[0060] Comparative Example 4 The difference between Comparative Example 4 and Example 1 is that, instead of plasma treatment of the active material NaCoO2, 88g of surface-modified NaCoO2 and 4g of conductive carbon black were directly placed into the plasma. Figure 1 The electrode powder stirring device shown is the same as in Example 1, except for the other steps.

[0061] A 180° peel test was performed on this comparative example, and the average peel strength was 10.8 N / cm. After assembling the electrodes into a sodium half-cell, the initial sodium intercalation capacity at 0.1 C rate was 117 mAh / g, and the capacity retention rate was 97% after 400 cycles.

[0062] Comparative Example 1 uses a single 65 μm thick PAA self-supporting membrane structure. The single PAA membrane system lacks the three-dimensional cohesive network formed by PTFE fiberization, failing to effectively buffer the volume deformation of the active material during charge and discharge. Although the peel strength reaches 18 N / cm, the capacity retention and rate performance after 400 cycles are significantly reduced. Comparative Example 2 uses a single 65 μm thick PTFE self-supporting membrane structure, lacking the hydrogen bonding reinforcement between the PAA interface layer and the current collector. It relies solely on the physical adsorption of PTFE for interfacial bonding, resulting in a peel strength of only 8.2 N / cm, which cannot meet the interfacial stability requirements under high-rate charge and discharge and long-term vibration conditions. Comparative Example 3 places the PTFE membrane between the current collector and the PAA membrane, preventing the PAA membrane from directly contacting the current collector to form hydrogen bonds. The peel strength is only 9 N / cm, and the interfacial contact impedance is significantly increased, resulting in an initial discharge capacity of only 99 N / cm at 0.1 C. The capacity retention rate was only 89% after 400 cycles, and the electrochemical performance deteriorated significantly. Comparative Example 4 omitted the plasma surface modification step of the active material, which failed to introduce sufficient polar groups on the surface of the active material. This resulted in a significant decrease in the interfacial compatibility between the active material and the binder, insufficient uniformity of binder dispersion and fibrillation, and a peel strength of only 10.8 N / cm.

[0063] All aspects, embodiments, and features of this invention should be considered illustrative in all respects and not limiting of the invention; the scope of the invention is defined only by the claims. Other embodiments, modifications, and uses will become apparent to those skilled in the art without departing from the spirit and scope of the invention as claimed.

[0064] In the preparation method of this invention, the order of the steps is not limited to the listed order. For those skilled in the art, variations in the order of the steps without creative effort are also within the scope of protection of this invention. Furthermore, two or more steps or actions can be performed simultaneously.

[0065] Finally, it should be noted that the specific embodiments described herein are merely illustrative examples of the invention and are not intended to limit the implementation of the invention. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to replace them; it is neither necessary nor possible to exemplify all embodiments here. However, these obvious variations or modifications derived from the essential spirit of the invention still fall within the scope of protection of the invention, and interpreting them as any additional limitation would contradict the spirit of the invention.

Claims

1. A method for preparing a dry-process ultra-strong peeling force electrode, characterized in that, Includes the following steps: Step 1: Surface modification of the active material is performed by plasma treatment to obtain surface-modified active material; Surface-modified active material, conductive agent, and polyacrylic acid binder are stirred evenly in an electrode powder stirring device to obtain PAA-containing composite powder; surface-modified active material, conductive agent, and polytetrafluoroethylene binder are stirred evenly in an electrode powder stirring device to obtain PTFE-containing composite powder. Step 2: The PAA-containing composite powder and the PTFE-containing composite powder are respectively fed into a roller press for pre-pressing to form a PAA-containing self-supporting electrode film and a PTFE-containing self-supporting electrode film. The current collector, the PAA-containing self-supporting electrode film and the PTFE-containing self-supporting electrode film are stacked in the order of stacking and then fed into the roller press for main pressing to form the electrode film layer. Step 3: The electrode film is sent into an activation furnace. In an inert atmosphere, it is heated to achieve in-situ cross-linking of the binder and interface activation. After cooling, a dry-process ultra-strong peeling electrode is obtained.

2. The preparation method according to claim 1, characterized in that, The active material is one or more of battery layered oxides, hard carbon, and graphite, and the layered oxide is NaCoO2 or NaFe. 0.5 Mn 0.5 O2, LiCoO2, LiFe 0.5 Mn 0.5 One or more of O2, wherein the conductive agent is one or more of superconducting carbon black, acetylene black, Ketjen black, carbon nanofibers, graphene, and graphene oxide.

3. The preparation method according to claim 1, characterized in that, In step 1, the mass ratio of surface-modified active material, conductive agent and polyacrylic acid binder in the PAA-containing composite powder is 20~24:1:2~3; in the PTFE-containing composite powder, the mass ratio of surface-modified active material, conductive agent and polytetrafluoroethylene binder is 29~32:1:0.8~1.

2.

4. The preparation method according to claim 1, characterized in that, The plasma processing power in step 1 is 100-300 W, and the processing time is 5-15 min.

5. The preparation method according to claim 1, characterized in that, In step 1, the surface-modified active material and conductive agent are first added to the electrode powder stirring device and stirred for 10-40 min. The mixture is then heated to 70-95 °C. After adding polyacrylic acid binder or polytetrafluoroethylene binder, the temperature is maintained and stirring is continued for 5-30 min to obtain PAA-containing composite powder or PTFE-containing composite powder.

6. The preparation method according to claim 1, characterized in that, The stirring speed of the electrode powder is 3000~12000 r / min, and the working atmosphere of the electrode powder stirring device is an inert atmosphere.

7. The preparation method according to claim 1, characterized in that, The surface roughness Ra of the current collector is controlled between 0.5 and 2.0 μm; the pre-compression pressure is 5-10 MPa, the main pressure is 25-50 MPa, and the compaction temperature is 80-100 ℃.

8. The preparation method according to claim 1, characterized in that, In step 2, the thickness of the PAA-containing self-supporting electrode film is 5-30 μm, and the thickness of the PTFE-containing self-supporting electrode film is 45-100 μm.

9. The preparation method according to claim 1, characterized in that, In step 3, the heating temperature is 150~200℃, the heating rate is 5~10℃ / min, and the holding time is 40~60 min.

10. An electrode powder stirring apparatus for the preparation method of claim 1, characterized in that, include: Base bracket, rocker arm, column guide rail, motor box, stirring assembly, reaction vessel, heating device, and anti-slip feet; The base support has anti-slip feet at the bottom and an integrated heating device mounting position at the top for fixing the heating device; the column guide rail is vertically fixed to one side of the base support, and a rocker arm is provided at the top of the column guide rail; the motor box is slidably connected to the column guide rail, and the motor box can be driven to move up and down along the column guide rail by rotating the rocker arm; the output end of the motor box is connected to the stirring assembly, and the stirring assembly includes at least two blades with different structures; the reaction vessel is located below the stirring assembly, and the top of the reaction vessel is sealed to the bottom of the motor box by a sealing ring, and the heating device is nested at the bottom of the reaction vessel; The surface of the column guide rail is marked with scale markings. The stroke range of the motor box is 50~200 mm. The motor box has a built-in speed-regulating motor with an output speed range of 0~15000 r / min, which can realize stepless speed regulation. The stirring assembly includes at least two blades with different structures, including a first blade with a gear-type structure and a second blade with a spiral structure. The blade tip extends to the inner wall area of ​​the reactor. The height of the second blade is adjustable from 0 to 5 mm.

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