A whole-process source anti-bubble process for lithium battery electrode slurry

Abstract

The application discloses a kind of lithium battery electrode slurry full-process source anti-bubble process, comprising: step S1, raw material gas phase passivation treatment operation: obtain degassed solvent and passivated powder;Step S2, oxygen-free laminar flow sealing transport premixing operation: stirring evenly obtains no gas premixing slurry;Step S3, execute stirring slurry operation: no gas premixing slurry is sent into closed slurry kettle, slurry is stirred, and the temperature in kettle and turbulent intensity are controlled;In the preset time interval during the execution step S3, the interface thermodynamics bubble locking operation of step S4 and the micro-positive pressure closed-loop gas protection and discharging operation of step S5 are executed, and after the completion of slurry stirring operation in step S3, the finished product slurry is obtained and is transported outward.The application constructs full-chain bubble blocking system, realizes full-process zero bubble generation, does not need post-processing, no residual pollution, the technical effect that slurry structure is complete, significantly improves pole piece coating yield and battery electrochemical performance.

Description

Technical Field

[0001] This invention relates to the field of lithium battery electrode slurry preparation technology, and in particular to a process for preventing air bubbles at the source of the entire lithium battery electrode slurry process. Background Technology

[0002] Lithium-ion batteries have been widely used in digital products, electric vehicles, and energy storage due to their advantages such as high energy density, good cycle performance, and being green and pollution-free. Lithium-ion battery electrode slurry is a high-viscosity suspension formed by mixing active materials, conductive agents, binders, and solvents (NMP or deionized water) in a certain proportion. It is a core intermediate material that determines the quality of the electrode and the performance of the battery.

[0003] In the preparation of lithium battery electrode slurry, the generation and residue of air bubbles is a common problem that the industry has long faced. Air bubbles in the slurry can cause problems such as pinholes, uneven thickness, and excessive surface roughness on the electrode sheet after the slurry is coated on the electrode surface. This can lead to a series of adverse consequences, such as increased internal resistance of the electrode sheet, accelerated capacity decay, shortened cycle life, and reduced safety performance.

[0004] Currently, the technical solutions for addressing slurry bubble problems in the industry are all passive treatments, with the core idea being "to allow bubble formation first, and then remove them through post-treatment." These solutions mainly fall into the following three categories: 1. Vacuum Degassing Technology: This method uses vacuum stirring, vacuum settling, and vacuum filtration to expand and burst bubbles under negative pressure. However, this approach has several drawbacks: First, the vacuum level is limited (typically -0.08 to -0.1 MPa), making it impossible to completely remove micron-sized microbubbles (<5 μm). Second, high vacuum can lead to solvent evaporation, fluctuations in slurry solid content, and decreased viscosity stability. Third, vacuum degassing takes 30-120 minutes, resulting in low production efficiency and high energy consumption. Fourth, the vacuum environment can allow outside air to backflow through equipment gaps, leading to secondary gas generation.

[0005] 2. Adding chemical defoamers: By adding silicone, polyether, or fatty acid amide defoamers, the gas-liquid interfacial tension is reduced, promoting bubble collapse. The fatal flaw of this approach is the residual pollution from the defoamers: they adhere to the surfaces of active materials and conductive agents, damaging the electrode interfacial conductivity, increasing battery internal resistance, and reducing cycle stability and rate performance. Furthermore, the defoamers have poor compatibility with the slurry system, easily leading to slurry stratification, precipitation, and deterioration of rheological properties, affecting coating quality.

[0006] 3. Physical post-treatment defoaming: This includes auxiliary methods such as ultrasonic crushing, centrifugal separation, mechanical foam scraping, and filter screen filtration. These methods can only remove some macroscopic bubbles and have limited effectiveness in removing microscopic bubbles. Furthermore, high-power ultrasound can damage the conductive network structure of the slurry, strong centrifugation easily leads to solid-liquid stratification, and filter screen filtration is prone to clogging and cannot remove internally encapsulated bubbles.

[0007] Therefore, there is an urgent need to develop a technology that can fundamentally solve the problem of air bubbles in lithium battery slurry and improve electrode quality and battery performance. Summary of the Invention

[0008] The purpose of this invention is to address the technical deficiencies of existing technologies by providing a process for preventing air bubbles at the source of the entire lithium battery electrode slurry process.

[0009] Therefore, this invention provides a process for preventing air bubbles at the source of the entire lithium battery electrode slurry process, including the following steps: Step S1, raw material vapor phase passivation treatment operation: the solvent used to prepare the slurry is subjected to gas bubbling degassing treatment to obtain degassed solvent, and the powder used to prepare the slurry is subjected to nitrogen coating treatment to obtain passivated powder. Step S2, oxygen-free laminar flow sealed conveying premixing operation: The passivated powder obtained in step S1 and the degassed solvent are simultaneously fed into a hollow sealed oxygen-free mixing premixing chamber, and then stirred evenly under a nitrogen atmosphere at a preset pressure to obtain a uniform gas-free premixed slurry with no air contact throughout the process. Step S3, perform stirring and pulping operation: the airless premixed slurry obtained in step S2 is fed into a closed pulping kettle, and then the slurry is stirred to control the temperature and turbulence intensity inside the kettle and maintain the rheological stability of the slurry; Within a preset time interval during the execution of step S3, the following step S4 is also executed; Step S4, perform interfacial thermodynamic bubble locking operation: add an interfacial modifier to the slurry to stabilize the interfacial tension of the slurry and suppress the bubble nucleation path; The process of executing step S3 also includes step S5; Step S5, perform micro-positive pressure closed-loop environmental gas and discharge operation: throughout the pulping process in step S3, maintain the inside of the closed pulping kettle in a micro-positive pressure nitrogen and low oxygen environment, so that after the pulp stirring operation in step S3 is completed, the finished pulp is obtained and transported outward.

[0010] As can be seen from the technical solution provided by the present invention above, compared with the prior art, the present invention provides a source-based anti-bubble process for lithium battery electrode slurry. Its scientific design can effectively overcome the defects of passive defoaming, residual pollution, structural damage, and low efficiency in the prior art. It constructs a full-chain bubble blocking system from five root causes: gas content in raw materials, gas entrapment during transportation, gas generation during stirring, interface nucleation, and external gas permeation. It achieves the technical effect of zero bubble generation throughout the process, no post-processing required, no residual pollution, and intact slurry structure. It significantly improves the electrode coating yield and battery electrochemical performance, and has great practical significance. Attached Figure Description

[0011] Figure 1 This invention provides a basic flow chart of a full-process source-based anti-bubble process for lithium battery electrode slurry. Detailed Implementation

[0012] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0013] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0014] In the description of this patent, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection or setting, a detachable connection or setting, or an integral connection or setting. Those skilled in the art can understand the specific meaning of the above terms in this patent according to the specific circumstances.

[0015] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0016] To enable those skilled in the art to better understand the present invention, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. Details not specified in the detailed embodiments are all conventional techniques in the industry.

[0017] See Figure 1 This invention provides a process for preventing air bubbles at the source of lithium battery electrode slurry throughout the entire process, including the following steps: Step S1, raw material vapor phase passivation treatment operation: the solvent used to prepare the slurry is subjected to gas bubbling degassing treatment to obtain degassed solvent, and the powder used to prepare the slurry is subjected to nitrogen coating treatment to obtain passivated powder. It should be noted that the powder used to prepare the slurry is a solid substance in the slurry, which is different from the liquid solvent.

[0018] In specific implementation, step S1 includes the following steps S11 and S12; Step S11: The solvent is fed into a hollow solvent low-temperature degassing tank (e.g., a cylindrical tank), and nitrogen gas is introduced into the solvent for nitrogen bubbling degassing treatment to obtain the degassed solvent. In specific implementation, in step S11, nitrogen gas is introduced into the solvent under pressure conditions of 0.02-0.05 MPa and temperature conditions of 5-15°C to carry out nitrogen bubbling degassing treatment. In specific implementation, in step S11, the temperature of the inner cavity of the solvent low-temperature degassing tank (i.e., the working temperature) is 5-15℃; In specific implementation, in step S11, nitrogen is introduced into the solvent through a micro-positive pressure nitrogen bubbling module for nitrogen bubbling degassing treatment.

[0019] It should be noted that the micro-positive pressure nitrogen bubbling module is a commonly used gas delivery and mixing device in chemical, semiconductor and photocatalysis experiments. It is a conventional device with mature existing technology. Its core principle is to use a micro-positive pressure environment to introduce high-purity nitrogen into the liquid medium, and to achieve stirring, degassing or homogenization of the liquid or reactants through bubbling.

[0020] It should be noted that, regarding step S11, one specific implementation method is as follows: NMP (positive electrode solvent) or deionized water (negative electrode solvent) is introduced into a solvent low-temperature degassing tank, the temperature is controlled at 5-15℃, the nitrogen pressure is slightly positive at 0.02-0.05MPa, the nitrogen bubbling flow rate is 0.5-1.5L / min, and the treatment time is 30-60min; after treatment, the dissolved oxygen content in the solvent is ≤50ppb and there are no visible free bubbles; that is, after detecting dissolved oxygen ≤50ppb and no free bubbles, it is ready for use.

[0021] Step S12: The powder is fed into a hollow, sealed powder surface inert coating chamber (e.g., a sealed container), and then nitrogen gas is introduced. Under the nitrogen atmosphere, a nitrogen molecule adsorption layer is formed on the powder surface, completing the nitrogen coating treatment, thereby obtaining passivated powder, which is then sealed and stored.

[0022] In specific implementation, in step S12, the nitrogen gas is nitrogen gas with a purity of ≥99.995%.

[0023] In specific implementation, in step S12, the passivated powder is sealed and stored in a sealed chamber with a nitrogen atmosphere at a pressure of 0.02-0.03 MPa.

[0024] In specific implementation, in step S12, under a nitrogen atmosphere, the powder is subjected to pulsed gas-solid fluidization coating treatment to form a uniform nitrogen molecule adsorption layer on the powder surface, thereby suppressing air adsorption.

[0025] Furthermore, the pulsed gas-solid fluidization coating process specifically involves introducing periodic pulsed nitrogen gas flow into the inert coating chamber on the powder surface and continuing the treatment for a preset time (e.g., 15-30 min) until a uniform nitrogen molecule adsorption layer is formed on the powder surface.

[0026] Furthermore, the pulse frequency of the pulsed nitrogen gas flow is 5-15Hz, and the pulse pressure is 0.1-0.3Mpa.

[0027] It should be noted that, regarding step S12, one specific implementation method is as follows: The positive electrode active material (ternary / lithium iron phosphate), the negative electrode active material (graphite / silicon carbide), and the conductive agent (carbon black / carbon nanotubes) are placed into the inert coating chamber on the powder surface. High-purity nitrogen gas with a purity ≥99.995% is introduced, and the pulsed gas-solid fluidization module is started with a pulse frequency of 5-15Hz and a pulse pressure of 0.1-0.3MPa for 15-30 minutes. After treatment, a uniform nitrogen molecule adsorption layer (thickness -20nm) is formed on the powder surface, inhibiting the adsorption of air by the powder.

[0028] It should be noted that the pulsed gas-solid fluidization module is a unit device that uses periodic pulsed airflow to replace constant air supply, causing solid particles to produce an intermittent and intense fluidization state. It is a conventional device with mature existing technology and is designed to solve the channeling, dead zone and overheating problems of easily agglomerated and difficult-to-flow materials in traditional continuous fluidization.

[0029] In specific implementation, in step S11, the time for nitrogen bubbling degassing of the solvent is 30-60 minutes. In step S12, the nitrogen coating treatment (i.e., pulsed gas-solid fluidization coating treatment) of the powder takes 15-30 minutes.

[0030] Step S2, oxygen-free laminar flow sealed conveying premixing operation: The passivated powder obtained in step S1 and the degassed solvent are simultaneously fed into a hollow sealed oxygen-free mixing premixing chamber (e.g., a hollow sealed container), and then stirred evenly under a nitrogen atmosphere at a preset pressure to obtain a uniform gas-free premixed slurry with no air contact throughout the process. In specific implementation, in step S2, a nitrogen atmosphere with a preset pressure is set, specifically a nitrogen atmosphere with a pressure of 0.02 MPa.

[0031] In specific implementation, in step S2, the nitrogen atmosphere (i.e., nitrogen micro-positive pressure atmosphere) in the oxygen-free mixing premixing chamber is a nitrogen atmosphere of 0.02 MPa.

[0032] In specific implementation, in step S2, the stirring speed is 20-40 r / min and the stirring time is 5-10 min.

[0033] It should be noted that, in specific implementation, the passivated powder obtained in step S1 can be fed into the oxygen-free mixing premixing chamber through an existing conventional sealed powder screw conveyor, and the degassed solvent can be fed into the oxygen-free mixing premixing chamber through a guide pipe.

[0034] It should be noted that, regarding step S2, in specific implementation, regarding powder conveying, one embodiment is as follows: the passivated powder is conveyed into the oxygen-free mixing premixing chamber by a sealed powder screw conveyor, maintaining a nitrogen micro-positive pressure of 0.02MPa, and a conveying speed of 0.5-2.0m / min. It should be noted that, regarding step S2, specifically in terms of solvent delivery: the degassed solvent flows into the oxygen-free mixing premixing chamber through a solvent laminar flow guide pipe in a laminar flow state with a Reynolds number Re < 200; wherein, the inner wall of the solvent laminar flow guide pipe is provided with spiral laminar flow ribs, the rib height is 0.15-0.25 times the pipe diameter, and the lead is 1.5-2 times the pipe diameter, so that the solvent flows in a laminar flow state with a Reynolds number Re < 200, without jetting, entrainment, or eddies; It should be noted that the oxygen-free mixing premixing chamber is a hollow, sealed chamber that maintains a slightly positive nitrogen atmosphere (0.02 MPa). A mixer (i.e., a conventional battery slurry mixer) is installed inside. The mixer drives the stirring paddle to rotate at a speed of 20-40 r / min. Powder and solvent are fed in simultaneously and premixed for 5-10 minutes to form a uniform, airless premixed slurry with no air contact throughout the process.

[0035] Step S3, perform stirring and pulping operation: the airless premixed slurry obtained in step S2 is fed into a closed pulping kettle, and then the slurry is stirred to control the temperature and turbulence intensity inside the kettle and maintain the rheological stability of the slurry; Specifically, in step S3, the nitrogen atmosphere (i.e., nitrogen micro-positive pressure atmosphere) in the oxygen-free mixing premixing chamber is a nitrogen atmosphere of 0.01-0.04 MPa, and the oxygen content is ≤100 ppm.

[0036] It should be noted that, regarding step S3, in specific implementation, one method for feeding the slurry into the reactor is as follows: the gas-free premixed slurry is fed into the sealed pulping reactor, and the micro-positive pressure closed-loop environmental gas is started to maintain the nitrogen micro-positive pressure in the reactor at 0.01-0.04MPa and the oxygen content at ≤100ppm; In specific implementation, in step S3, the stirring speed is 50-150 r / min; the stirring time is 40-80 min; Internal temperature: 25-45℃; Internal turbulence intensity: <5%; In specific implementation, in step S3, the stirring paddle is started to perform low-turbulence stirring of the slurry; It should be noted that the stirring paddle has the following characteristics: surface roughness Ra≤0.6μm; number of blades 2-4, with continuous wavy edges (wave height 5-15mm, wavelength 20-40mm); it generates a laminar flow field during stirring, with turbulence intensity <5% inside the vessel, and no strong shearing or eddy air entrainment.

[0037] It should be noted that, regarding step S3, in terms of specific implementation, one method of biomimetic stirring is as follows: start the stirring paddle, control the rotation speed to 50-150 r / min and the temperature inside the vessel to 25-45℃, and stir for 40-80 min; the turbulence intensity inside the vessel is <5%, with no strong shearing and no eddy air entrainment.

[0038] It should be noted that the sealed pulping vessel is a hollow, pressure-resistant, and sealed structure with a design pressure of 0.1 MPa. It is equipped with a nitrogen inlet, an oxygen content monitoring port, and a temperature sensor. In specific implementation, in step S3, the temperature of the sealed pulping kettle is controlled within the range of 25-45℃, and the temperature fluctuation is ≤±1℃, so as to avoid gas evolution caused by temperature changes due to fluctuations in gas solubility.

[0039] It should be noted that in step S3, the stirring paddle speed is 50-150 r / min, the pulping temperature is 25-45℃, the pulping time is 40-80 min, the turbulence intensity inside the vessel during pulping is <5%, and no post-treatment defoaming methods such as vacuum, ultrasound, or centrifugation are introduced.

[0040] Within a preset time interval during the execution of step S3, the following step S4 is also executed; Step S4, perform interfacial thermodynamic bubble locking operation: add an interfacial regulator to the slurry to stabilize the interfacial tension of the slurry and suppress the bubble nucleation path.

[0041] Specifically, during step S3, the preset time interval refers to the period between 40% and 60% of the total slurry mixing time. For example, if the total slurry mixing time is 80 minutes, the interface modifier is added to the slurry between 32 and 48 minutes after mixing begins. The reason for adding the interface modifier at a uniform rate in the middle of the pulping process in step S3, rather than at the beginning, is to avoid affecting powder diffusion if added initially.

[0042] In specific implementation, in step S4, the amount of interface modifier added accounts for 0.02-0.08 wt% of the total mass of the slurry.

[0043] It should be noted that, in this invention, in step S4, an interfacial thermodynamic bubble-locking operation is performed: by uniformly adding 0.02-0.08 wt% of fluorinated modified polyether interfacial regulator during the middle stage of pulping (40%-60% of the total time), the interfacial tension of the pulp is stabilized, and the nucleation path of bubbles is blocked.

[0044] In specific implementation, in step S4, the interface modifier is specifically a fluorinated polyether compound; The molecular formula of the fluorinated polyether compound is: CnF 2n+1 –O–(CH2CH2O) m –H, where n=4-8, m=6-12; It should be noted that the amount of interface modifier added is 0.02-0.08 wt% of the total mass of the slurry; this modifier only reduces the solid-liquid interfacial tension (for example, it can be reduced from 45-55 mN / m to 28-35 mN / m), and does not reduce the gas-liquid interfacial tension (it is maintained at 38-42 mN / m), thus thermodynamically inhibiting bubble nucleation.

[0045] It should be noted that the interface modifier in step S4 is added during the 40%-60% stage of the total pulping time in step S3. After the addition, the interfacial tension of the pulp is stabilized at 28-35mN / m, with fluctuations ≤±2mN / m. No silicone or polyether defoamers need to be added during the entire pulping process.

[0046] In specific implementation, in step S4, during the process of adding the interface modifier, the interface tension of the slurry is monitored in real time by an online interface tension monitoring instrument (a conventional device with mature existing technology), and the interface tension of the slurry is controlled to be stable within the preset interface tension range (specifically 28-35mN / m), so as to control the fluctuation of the interface tension of the slurry to be ≤ the preset value (specifically ±2mN / m). It should be noted that, in this invention, the interface modifier only reduces the solid-liquid interfacial tension, not the gas-liquid interfacial tension, and can effectively block the bubble nucleation path.

[0047] The process of executing step S3 also includes step S5; Step S5, perform micro-positive pressure closed-loop environmental gas and discharge operation: throughout the pulping process in step S3, maintain the inside of the closed pulping kettle in a micro-positive pressure nitrogen and low oxygen environment, so that after the pulp stirring operation in step S3 is completed, the finished pulp is obtained and transported outward.

[0048] In specific implementation, in step S5, the inside of the sealed pulping vessel is in a nitrogen micro-positive pressure and low oxygen environment, specifically: the inside of the sealed pulping vessel is in an environment with a nitrogen micro-positive pressure of 0.01-0.04 MPa and an oxygen content of ≤100 ppm.

[0049] In specific implementation, in step S5, the oxygen content in the closed pulping vessel is monitored in real time. Specifically, the oxygen content in the closed pulping vessel is monitored in real time by an online oxygen content monitor (a conventional device known to the public), and the gas pressure in the closed pulping vessel is detected by a gas pressure detection device (such as a gas pressure gauge) (i.e., whether it is 0.01-0.04 MPa). It should be noted that this invention maintains gas supply throughout the entire pulping process: a slight positive pressure of nitrogen (0.01-0.04 MPa) and an oxygen content ≤100 ppm are maintained throughout the pulping process; when the oxygen content exceeds the standard, gas is replenished (i.e., nitrogen is added) to the sealed pulping vessel through the gas replenishment valve to prevent outside air from seeping in; therefore, this invention can achieve bubble-free discharge: after pulping is completed, the number of detected bubbles in the pulp is <0.5 per mL and the maximum particle size is <1.5 μm, and then it can be directly sealed and discharged without vacuum degassing, ultrasonic treatment or the addition of defoamers, and can be directly used in the coating process.

[0050] It should be noted that the online oxygen content monitor has a monitoring accuracy of ±5ppm and displays the oxygen content in the reactor in real time. The purpose is to control the oxygen content in the closed pulping reactor to ≤100ppm. It should be noted that the response time of the gas replenishment valve is ≤1s. It is opened when the oxygen content is >100ppm or the pressure in the sealed pulping kettle is <0.01MPa to replenish high-purity nitrogen. In practice, a pressure relief valve is installed on the shell wall of the sealed pulping vessel, with a safety pressure of 0.05 MPa, which is conducive to timely pressure relief and prevents the gas pressure inside the sealed pulping vessel from being too high.

[0051] It should be noted that in step S5, when the oxygen content in the sealed pulping vessel is >100ppm, the gas replenishment valve is activated to replenish high-purity nitrogen. When the pressure in the sealed pulping vessel is below 0.01MPa, nitrogen is replenished to ensure that no external air backflows in and seeps in throughout the process. The discharged slurry does not require degassing treatment and can be used directly for coating.

[0052] To better understand the technical solution of the present invention, the technical principles of the present invention are explained below.

[0053] This invention addresses the five essential conditions for bubble formation (gas source, entrainment dynamics, nucleation interface, growth space, and external infiltration) and specifically constructs five core technologies to block bubble formation pathways from multiple dimensions, including physical, chemical, flow field, and thermodynamic perspectives. 1. Raw material gas phase passivation: Low-temperature micro-positive pressure nitrogen bubbling removes dissolved oxygen and free gas bubbles from the solvent; pulsed gas-solid fluidization forms a uniform nitrogen molecule adsorption layer on the powder surface, inhibiting the adsorption of air by the powder and eliminating the source of gas.

[0054] 2. Oxygen-free laminar flow sealed conveying: Adopting superhydrophobic low-adhesion spiral conveying and laminar flow guiding technology, the powder and solvent are conveyed in a laminar flow state (Re<200) in a sealed manner, without jetting, entrainment, or air contact, eliminating the addition of air bubbles during the conveying process.

[0055] 3. Low-turbulence mixing and pulping: The mixing impeller is designed to create a low-turbulence flow field (turbulence intensity < 5%), with no strong shear, no eddy air entrainment, no local stagnant air, and no bubbles generated during the mixing process.

[0056] 4. Interfacial thermodynamic bubble locking: Develop fluorinated polyether selective interface modifiers that only reduce the solid-liquid interfacial tension and do not reduce the gas-liquid interfacial tension, thereby increasing the thermodynamic barrier for bubble nucleation by 3-5 times, preventing bubble nucleation and growth (not eliminating them after formation).

[0057] 5. Micro-positive pressure closed-loop environmental gas: The entire process maintains a micro-positive pressure of nitrogen (0.01-0.04MPa), with an oxygen content of ≤100ppm inside the reactor, preventing outside air from seeping in through shaft seals, flanges, and gaps, and requiring no new gas supply.

[0058] To better understand the technical solution of the present invention, the following specific embodiments will be used to illustrate the technical solution of the present invention.

[0059] Example 1.

[0060] In Example 1, the present invention provides a complete anti-bubble preparation process for ternary cathode slurry of lithium battery, and the specific raw material formula (10kg batch) is as follows: The slurry comprises the following components in the following mass ratio: main material: 8.0 kg; conductive carbon black: 0.5 kg; carbon nanotubes: 0.2 kg; PVDF: 0.8 kg; NMP: 0.5 kg; The mass of the fluorinated modified polyether used as an interface modifier is 0.004 kg (0.04 wt% of the total mass of the slurry).

[0061] The present invention provides a complete process for preparing ternary cathode slurry for lithium batteries with anti-bubble properties, comprising the following steps: Step S1, raw material vapor phase passivation treatment, specific requirements are as follows: Solvent NMP treatment: bubbling with nitrogen at 10℃ and 0.03MPa for 50 min, dissolved oxygen 35ppb, no free bubbles; Powder treatment: NCM, conductive carbon black, and carbon nanotubes are added to the coating chamber and pulsed with high-purity nitrogen for 25 minutes (pulse frequency 10Hz, pressure 0.2MPa) to make the nitrogen adsorption layer on the powder surface uniform.

[0062] Step S2, oxygen-free laminar flow sealed conveying premixing, specific requirements are as follows: Powder is conveyed by a sealed screw conveyor (0.02MPa nitrogen, 1.2m / min); solvent NMP is guided through a guide pipe (Re=160); the premixing chamber is equipped with 0.02MPa nitrogen and the slurry is stirred at 30r / min for 8min to produce an airless premixed slurry.

[0063] Step S3, low-vortex stirring pulping, specific requirements are as follows: In a 50L sealed reactor, the nitrogen pressure was slightly positive at 0.025MPa and the oxygen content was 65ppm; the stirring speed was 120r / min, and the stirring was carried out at 35℃ for 65min with a turbulence intensity of 3.8%; the viscosity of the slurry was stably controlled at 12000mPa·s with fluctuations ≤±300mPa·s.

[0064] Step S4, interfacial thermodynamic bubble locking, specific requirements are as follows: When the pulping process in step S3 reaches 35 minutes (i.e., the middle stage of pulping), 0.04 wt% of fluorinated polyether is added at a uniform rate; the interfacial tension of the pulp is stable at 31 mN / m, with fluctuations ≤ ±1.5 mN / m.

[0065] Step S5, material discharge and performance testing, has the following specific requirements: For the slurry, the detected slurry bubbles were 0.3 per mL with a maximum particle size of 1.2 μm; then the finished slurry was obtained and transported outwards.

[0066] In this invention, the slurry obtained through the above operations is coated onto the current collector of the battery electrode. After conventional operations such as drying and cutting, the battery electrode (i.e., the electrode) is obtained. The battery electrode obtained in this invention is tested, and the performance data obtained are: coating pinhole rate: 0.04%; electrode surface density fluctuation: ±0.7%. Furthermore, the performance of a ternary battery prepared based on this battery electrode is further tested, and the performance data are: battery internal resistance reduced by 9%; capacity retention rate after 1000 cycles is 90.2%.

[0067] In summary, compared with existing technologies, this invention provides a source-based anti-bubble process for lithium battery electrode slurry. Its scientific design effectively overcomes the shortcomings of existing technologies, such as passive defoaming, residual pollution, structural damage, and low efficiency. It constructs a full-chain bubble blocking system from five root causes: gas content in raw materials, gas entrapment during transportation, gas generation during stirring, interface nucleation, and external gas permeation. This achieves the technical effects of zero bubble generation throughout the process, no post-processing required, no residual pollution, and intact slurry structure. It significantly improves the electrode coating yield and battery electrochemical performance, and has significant practical implications.

[0068] This invention addresses the shortcomings of existing technologies that generally employ a passive treatment model of "generating gas first, then vacuum degassing or defoaming with defoaming agents," which suffers from issues such as residual bubbles, defoaming agent contamination, slurry structure damage, and low yield. This invention constructs five core technologies: raw material gas phase passivation, oxygen-free laminar flow sealed conveying, low-vortex biomimetic stirring, interfacial thermodynamic bubble locking, and micro-positive pressure closed environmental gas. These technologies completely block the bubble generation path from five root causes: raw material gas content, gas entrainment during conveying, gas generation through stirring, interfacial nucleation, and external gas infiltration.

[0069] This invention does not use vacuum, add silicone or polyether defoamers, or rely on ultrasonic or centrifugal post-treatment. Through physical interface control and flow field reconstruction, it achieves an initial bubble count of <0.5 bubbles / mL, a maximum particle size of <1.5μm, a coating pinhole rate of <0.05%, an electrode surface density fluctuation of ≤±0.8%, and a 6-10% improvement in battery capacity retention after 1000 cycles. It is applicable to positive and negative electrode slurries of all systems, including ternary, lithium iron phosphate, graphite, and silicon carbide, and has strong process compatibility and is easy to scale up.

[0070] Through practical testing, this invention is a proactive, source-blocking, residue-free, damage-free, highly efficient, and highly stable anti-bubble technology solution that can fundamentally solve the problem of bubble formation in lithium battery slurry and improve electrode quality and battery performance.

[0071] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A process for preventing air bubbles at the source throughout the entire process of lithium battery electrode slurry, characterized in that, Includes the following steps: Step S1, raw material vapor phase passivation treatment operation: the solvent used to prepare the slurry is subjected to gas bubbling degassing treatment to obtain degassed solvent, and the powder used to prepare the slurry is subjected to nitrogen coating treatment to obtain passivated powder. Step S2, oxygen-free laminar flow sealed conveying premixing operation: The passivated powder obtained in step S1 and the degassed solvent are simultaneously fed into a hollow sealed oxygen-free mixing premixing chamber, and then stirred evenly under a nitrogen atmosphere at a preset pressure to obtain a uniform gas-free premixed slurry with no air contact throughout the process. Step S3, perform stirring and pulping operation: the airless premixed slurry obtained in step S2 is fed into a closed pulping kettle, and then the slurry is stirred to control the temperature and turbulence intensity inside the kettle and maintain the rheological stability of the slurry; Within a preset time interval during the execution of step S3, the following step S4 is also executed; Step S4, perform interfacial thermodynamic bubble locking operation: add an interfacial modifier to the slurry to stabilize the interfacial tension of the slurry and suppress the bubble nucleation path; The process of executing step S3 also includes step S5; Step S5, perform micro-positive pressure closed-loop environmental gas and discharge operation: throughout the pulping process in step S3, maintain the inside of the closed pulping kettle in a micro-positive pressure nitrogen and low oxygen environment, so that after the pulp stirring operation in step S3 is completed, the finished pulp is obtained and transported outward.

2. The lithium battery electrode slurry whole-process source-level anti-bubble process as described in claim 1, characterized in that, Step S1 specifically includes the following steps S11 and S12; Step S11: The solvent is fed into a hollow solvent low-temperature degassing tank, and nitrogen is introduced into the solvent for nitrogen bubbling degassing treatment to obtain the degassed solvent. Step S12: The powder is fed into a hollow, sealed powder surface inert coating chamber, and then nitrogen gas is introduced. Under the nitrogen atmosphere, a nitrogen molecule adsorption layer is formed on the powder surface, completing the nitrogen coating treatment, thereby obtaining passivated powder, which is then sealed and stored.

3. The lithium battery electrode slurry whole-process source anti-bubble process as described in claim 2, characterized in that, In step S11, nitrogen gas is introduced into the solvent under pressure conditions of 0.02-0.05 MPa and temperature conditions of 5-15°C to perform nitrogen bubbling degassing treatment. In step S11, the temperature inside the solvent low-temperature degassing tank is 5-15℃; In step S12, the nitrogen gas is nitrogen gas with a purity ≥ 99.995%; In step S12, the passivated powder is sealed and stored in a sealed chamber with a nitrogen atmosphere at a pressure of 0.02-0.03 MPa. In step S11, the solvent is subjected to nitrogen bubbling degassing for 30-60 minutes; In step S12, the nitrogen coating treatment of the powder takes 15-30 minutes.

4. The lithium battery electrode slurry whole-process source-level anti-bubble process as described in claim 2, characterized in that, In step S12, under a nitrogen atmosphere, the powder is subjected to pulsed gas-solid fluidization coating treatment to form a uniform nitrogen molecule adsorption layer on the powder surface, thereby inhibiting air adsorption. The pulsed gas-solid fluidization coating process involves introducing periodic pulsed nitrogen gas flow into an inert coating chamber on the powder surface and continuing the process for a preset duration until a uniform nitrogen molecule adsorption layer is formed on the powder surface.

5. The lithium battery electrode slurry whole-process source-level anti-bubble process as described in claim 1, characterized in that, In step S2, a nitrogen atmosphere with a preset pressure is used, specifically a nitrogen atmosphere with a pressure of 0.02 MPa. In step S2, the nitrogen atmosphere in the oxygen-free mixing premixing chamber is a nitrogen atmosphere of 0.02 MPa; In step S2, the stirring speed is 20-40 r / min and the stirring time is 5-10 min.

6. The lithium battery electrode slurry whole-process source-level anti-bubble process as described in claim 1, characterized in that, In step S3, the nitrogen atmosphere in the oxygen-free mixing premixing chamber is a nitrogen atmosphere of 0.01-0.04 MPa, and the oxygen content is ≤100 ppm.

7. The lithium battery electrode slurry whole-process source-level anti-bubble process as described in claim 1, characterized in that, In step S3, the stirring speed is 50-150 r / min; Stirring time: 40-80 min; reactor temperature: 25-45℃; turbulence intensity: <5%.

8. The lithium battery electrode slurry whole-process source anti-bubble process as described in claim 1, characterized in that, Within the preset time interval during the execution of step S3, specifically: the time interval of 40%-60% of the total slurry mixing time in step S3; And / or, In step S4, the amount of interface modifier added is 0.02-0.08 wt% of the total mass of the slurry. And / or, In step S4, during the process of adding the interface modifier, the interface tension of the slurry is monitored in real time by an online interface tension monitor, and the interface tension of the slurry is controlled to be stable within the preset interface tension range, so as to control the fluctuation of the interface tension of the slurry to be less than or equal to the preset value.

9. The lithium battery electrode slurry whole-process source-level anti-bubble process as described in claim 1, characterized in that, In step S4, the interface modifier is specifically a fluorinated polyether compound. The molecular formula of the fluorinated polyether compound is: CnF 2n+1 –O–(CH2CH2O) m –H; Where n = 4 - 8, m = 6 - 12.

10. The lithium battery electrode slurry whole-process source-level anti-bubble process as described in claim 1, characterized in that, In step S5, the oxygen content inside the sealed pulping vessel is monitored in real time, specifically by using an online oxygen content monitor and a gas pressure detection device to detect the gas pressure inside the sealed pulping vessel.

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