Device and method for infiltrating battery cell of secondary battery

Abstract

The invention relates to a secondary battery cell infiltration device and method. The device comprises a containing cavity, an air pressure adjusting assembly, an electric field control assembly and an ultrasonic control assembly. According to the method, air pressure circulation, ultrasonic action and a pulsed electric field are coupled through time sequence cooperation, and after a pole piece is placed in a cavity electrolyte, air pressure is subjected to negative pressure stage circulation, normal pressure stage circulation and positive pressure stage circulation in sequence; ultrasonic waves are started synchronously in the air exhaust stage, an electric field is triggered instantly when negative pressure is converted into normal pressure, and the pressurization stage and the ultrasonic peak time period are overlapped; wherein the vibration direction of the ultrasonic wave is parallel to the electric field direction of the pulsed electric field along the thickness direction of the electrode, and the pulse frequency of the electric field is matched with the formant of the ultrasonic wave. And through multi-field cooperation of macroscopic pressure driving, microcosmic cavitation cleaning and interface energy regulation and control, the infiltration speed, depth and uniformity of the electrolyte on the thick electrode are improved. Optionally, the device can be integrated with a monitoring module for feeding back the infiltration completion degree in real time through micro-pulse detection.

Description

Technical Field

[0001] This application relates to the field of secondary battery manufacturing technology, and in particular to a secondary battery cell impregnation device and method. Background Technology

[0002] In the field of rechargeable battery manufacturing, electrolyte wetting is one of the key processes, and its efficiency and uniformity directly affect the battery's internal resistance, capacity, and cycle life. Current mainstream technologies mostly employ vacuum negative pressure or pressurized static placement methods, relying on macroscopic pressure differences to drive electrolyte penetration. However, these methods have significant limitations: First, macroscopic pressure is insufficient to effectively break up air bubbles trapped in the micron-level pores of the electrode by the liquid, resulting in a bubble residue rate typically exceeding 5%, forming localized ionic insulation points and increasing the battery's internal resistance. Second, for thick electrodes (e.g., 150 μm) designed for high energy density, the lack of effective means to actively reduce the interfacial tension between the electrolyte and electrode materials means that natural wetting relying solely on capillary action is extremely time-consuming, potentially exceeding 6 hours, severely restricting production cycle time. Furthermore, existing processes lack in-situ real-time monitoring of the wetting process, making it impossible to dynamically adjust process parameters based on the actual electrolyte penetration state. This makes it difficult to guarantee the uniformity of internal wetting within the battery, potentially causing capacity fluctuations of ±8% between individual cells. Therefore, there is an urgent need for a new wetting-related technology that can work synergistically, be precisely controlled, and have process feedback capabilities, in order to simultaneously address the challenges of microbubble removal and interfacial energy regulation. Summary of the Invention

[0003] The purpose of this application is to solve the problems of slow electrolyte wetting speed and excessive micropore bubble residue in thick electrodes. To achieve efficient, uniform, and controllable wetting of secondary battery cells, the application aims to significantly shorten wetting time, minimize bubble residue, and improve battery consistency. This objective is achieved through the following technical solution: a secondary battery cell wetting device comprising a receiving cavity, a pressure adjustment component, an electric field control component, and an ultrasonic control component. The receiving cavity contains the battery cell and electrolyte. The air pressure adjustment component is connected to the receiving cavity and is used to adjust the air pressure inside the receiving cavity; The electric field control component provides a pulsed electric field to the cavity. The ultrasonic control component provides ultrasonic waves to the electrolyte; The pulse frequency of the provided electric field matches the resonance peak of the ultrasonic wave.

[0004] In one embodiment, a monitoring module is also included, which provides real-time feedback on the completion of immersion through micro-pulse detection.

[0005] In one embodiment, the vibration direction of the ultrasonic wave is parallel to the electric field direction of the pulsed electric field.

[0006] In one embodiment, the pulse waveform of the pulsed electric field is an exponentially decaying pulse waveform, the vibration frequency of the ultrasonic wave is 40 kHz, and the amplitude is in the range of 0.03 mm to 0.08 mm.

[0007] In addition, this application provides a method for impregnating a secondary battery cell, comprising: Place the electrode in the electrolyte containing the cavity; The air pressure is adjusted, and the air pressure goes through the negative pressure stage, the normal pressure stage and the positive pressure stage in sequence. The cavity is made under negative pressure by evacuation. Ultrasonic vibration is started simultaneously at the beginning of the air pressure evacuation phase, and the pressurization phase overlaps with the peak period of ultrasonic vibration. The instantaneous change from negative pressure to normal pressure triggers a pulsed electric field, and the electric field effect lasts until the middle of the pressurization phase. In this process, the pulse frequency of the electric field matches the resonance peak of the ultrasonic wave.

[0008] In one embodiment, the pressure adjustment step involves multiple pressure adjustment cycles.

[0009] In one embodiment, the minimum air pressure during the negative pressure phase is less than -80 kPa, the maximum air pressure during the positive pressure phase is greater than 40 kPa, the duration of the negative pressure phase is in the range of 8 s to 20 s, the duration of the normal pressure phase is in the range of 2 s to 5 s, and the duration of the positive pressure phase is in the range of 10 s to 25 s.

[0010] In one embodiment, the vibration direction of the ultrasonic wave is parallel to the electric field direction of the pulsed electric field along the electrode thickness direction.

[0011] In one embodiment, the pulse waveform of the pulsed electric field is an exponentially decaying pulse waveform, which decays exponentially over time after the initial peak.

[0012] In one embodiment, the peak voltage of the pulsed electric field is in the range of 2V-6V and the decay constant is in the range of 0.05s-0.5s.

[0013] Compared with the prior art, this application has the following beneficial effects: This application employs a pressure regulating component to induce a pressure cycle within the containment cavity, consisting of negative pressure, normal pressure, and positive pressure stages. During the negative pressure stage, gas is evacuated from the electrode surface and macroscopic pores. During the positive pressure stage, the pressure difference drives the electrolyte to penetrate deeper into the electrode. Simultaneously, during the negative pressure stage, an ultrasonic control component is activated to provide the electrolyte with ultrasonic waves of a specific frequency and amplitude. The cavitation effect and mechanical vibration generated by the ultrasonic waves effectively break up air bubbles trapped within the electrode micropores and slightly disturb the pore structure, thereby reducing the electrolyte's permeation resistance at the microscale.

[0014] The electric field control component is triggered the instant the air pressure changes from negative to normal, providing a pulsed electric field of a specific waveform into the cavity. Through electrocapillary effect, this actively regulates the interfacial energy between the electrolyte and electrode materials, effectively reducing the contact angle and penetration barrier. This further promotes the initial spreading and capillary penetration of the electrolyte, building upon the ultrasonic breaking down of microscopic barriers. By matching the pulse frequency of the electric field with the resonance peak of the ultrasonic waves and ensuring that their directions of action are parallel along the electrode thickness, the electric field energy and ultrasonic vibration energy are superimposed and synergistically enhanced in both time and space, thus strengthening their overall effect on the electrode-electrolyte interface.

[0015] Furthermore, by setting up a monitoring module and employing micro-pulse detection, parameters such as the battery's internal resistance during the immersion process can be monitored and fed back in real time. This provides a quantitative basis for judging the completion of immersion, thereby achieving precise control of the process and avoiding over-immersion or under-immersion caused by fixed immersion times. Through multi-field coupling, the immersion time required by traditional processes, which used several hours, is shortened to less than 60 minutes. The combination of ultrasonic cavitation and pressure cycling effectively eliminates air bubbles in the electrode micropores, reducing the bubble residue rate to below 0.5%. This helps form a uniform solid electrolyte interface and improves the battery's cycle stability. Reducing battery performance differences caused by uneven immersion, the electrode surface density deviation can be controlled within 2%, thus contributing to improved overall battery pack capacity and cycle life. Attached Figure Description

[0016] Figure 1 This is a schematic flowchart of a secondary battery cell impregnation method in one embodiment of this application. Detailed Implementation

[0017] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, it should be noted that, for ease of description, only the parts relevant to this application are shown in the accompanying drawings, not the entire structure. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this application.

[0018] The terms “comprising” and “having”, and any variations thereof, used in this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus.

[0019] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0020] In the manufacturing process of secondary batteries, the thorough and uniform wetting of the electrolyte in the electrode pores is a key step to ensure battery performance and consistency. Traditional atmospheric pressure static or single-physical-field-assisted wetting methods face the following technical bottlenecks: First, macroscopic gas pressure circulation is difficult to effectively break up air bubbles trapped in the micro-nano pores of the electrodes, resulting in a high residual rate of air bubbles and affecting ion conduction pathways; Second, the lack of active interfacial energy regulation means that the initial spreading and deep penetration of the electrolyte into thick and dense electrodes is slow, and the wetting time is lengthy. To systematically solve the above problems, this application proposes a secondary battery cell wetting device and method based on multi-physical-field time-series coordination. This method couples a pulsed electric field of a specific waveform, high-frequency ultrasonic vibration, and programmed multi-stage gas pressure circulation, matching them in terms of timing, spatial direction, and frequency.

[0021] To make the above-mentioned objectives, features, and advantages of the present invention clearer and easier to understand, the device configuration, parameter settings of each component, synergistic timing of method steps, and resulting technical effects of the present invention will be described in detail below with reference to specific embodiments. A preferred embodiment of the secondary battery cell immersion device of this application includes a receiving cavity, a pressure adjustment component, an electric field control component, and an ultrasonic control component. The receiving cavity contains the battery cell and electrolyte. The pressure adjustment component is connected to the receiving cavity and is used to adjust the pressure within the receiving cavity. The electric field control component provides a pulsed electric field to the receiving cavity, and the ultrasonic control component provides ultrasonic waves to the electrolyte, wherein the pulse frequency of the provided electric field matches the resonance peak of the ultrasonic waves.

[0022] The containment cavity forms a sealed environment for the impregnation process, providing a controlled space for the interaction of the battery cell, electrolyte, and various physical fields. The pressure adjustment component is connected to this containment cavity and provides a macroscopic driving force for electrolyte penetration and assists in gas removal by programmatically changing the gas pressure within the cavity. Specifically, the component establishes a negative pressure environment by evacuating air, which can preferentially remove air from the electrode surface and larger pores, reducing the overall resistance to subsequent liquid phase penetration; then it switches to a positive pressure stage, using the pressure difference as an active driving force to pressurize the electrolyte into the deep pore structure of the electrode.

[0023] The ultrasonic control component provides ultrasonic waves to the electrolyte within the cavity. The high-frequency mechanical vibration generates cavitation in the liquid, creating and breaking microbubbles. This process effectively removes gas trapped within the micro- and nano-sized pores of the electrodes, clearing obstacles for electrolyte entry. Secondly, the acoustic flow effect induced by ultrasound in the electrolyte enhances mass transfer and convection within the liquid phase, helping to homogenize the ion distribution and reduce its apparent viscosity, thereby improving wettability. Applying vibrations in the frequency range of 20 kHz to 100 kHz to the electrolyte during the wetting process increases the microscopic mobility of electrolyte molecules, maximizing their contact performance with the electrode material interface and improving wetting. The application of ultrasound also helps form a thinner, inorganic-rich solid electrolyte interface film on the electrode surface, positively impacting the electrochemical performance of the battery. In specific implementations, this component can be constructed from transducers such as piezoelectric ceramic oscillators, converting electrical signals into mechanical vibrations through the inverse piezoelectric effect.

[0024] The electric field control component provides a pulsed electric field to the cavity, which actively regulates the solid-liquid interface energy between the electrode and the electrolyte through electrical means. When the pulsed electric field acts on the wetting interface, it can induce phenomena such as electrocapillary effect, effectively reducing the contact angle of the electrolyte on the solid surface of the electrode, thereby fundamentally enhancing the spreading ability and capillary penetration power of the electrolyte. The pulse frequency of the electric field provided by the electric field control component matches the resonance peak of the ultrasonic wave provided by the ultrasonic control component, enabling the two physical fields to work synergistically and couple. When the frequency component of the pulsed electric field matches the mechanical resonance peak of the ultrasonic transducer (such as a piezoelectric ceramic vibrator), stable high-intensity ultrasonic vibration can be excited and maintained more efficiently. At the same time, the timing coordination (such as triggering the pulsed electric field at a specific stage of gas pressure conversion) allows the electrolyte to be subjected to micro-perturbations from ultrasonic waves and macro-drives from gas pressure at the optimal moment when the interface energy is reduced due to the electric field, thereby synergistically accelerating the transport and pore filling process of the electrolyte at the micro, meso, and macro scales. The synergy of multiple physical fields in frequency and timing overcomes the limitations of single technical means, such as the difficulty of breaking microbubbles by air pressure alone, or the insufficient driving pressure of ultrasound on deep pores, thereby achieving a simultaneous improvement in wetting efficiency and thoroughness.

[0025] Building upon the synergistic effects of core physical fields such as air pressure, electric field, and ultrasound, a monitoring module is further integrated to achieve closed-loop control of the immersion process. This monitoring module provides real-time feedback on the immersion completion status through micro-pulse detection, based on the direct correlation between the battery's internal resistance characteristics and the electrolyte's filling state in the electrode pores. Specifically, during the immersion process, as the electrolyte gradually fills the electrode micropores, the battery's ion conduction pathway is continuously established, and its DC internal resistance exhibits a decreasing and stabilizing trend. Therefore, by applying a low-rate (e.g., 0.02C) micro-current pulse to the immersing cell and simultaneously measuring its terminal voltage response using a high-precision four-wire Kelvin test method, the real-time DC internal resistance value can be calculated, thereby quantitatively characterizing the degree of immersion. By integrating the micro-pulse detection module into the multi-field collaborative wetting system of this application, an objective and quantifiable termination criterion is provided for the wetting process. Through real-time feedback of internal resistance data, the system can dynamically determine whether the wetting has reached the preset completion standard, and control the duration or switching sequence of air pressure circulation, pulse electric field and ultrasonic vibration accordingly. This achieves an upgrade from "open-loop application" to "closed-loop control", which ultimately helps to improve the consistency of cell performance within a batch.

[0026] In the secondary battery cell immersion device, the vibration direction of the ultrasonic waves provided by the ultrasonic control component is set to be parallel to the electric field direction of the pulsed electric field provided by the electric field control component. Specifically, when the ultrasonic waves propagate in the electrolyte, the cavitation effect and acoustic flow effect they generate can effectively disturb the liquid, break microbubbles, and promote mass transport; while the pulsed electric field actively regulates the electrode-electrolyte interface energy through electrocapillary effects. In the process of multi-energy field coupling (such as coupling electric pulses and ultrasonic waves), the coordination of the physical field action direction is an important factor affecting its coupling effect. When the vibration direction of the ultrasonic waves is parallel to the electric field direction of the pulsed electric field, the two form a co-directional excitation in the electrode thickness direction. This ensures that the processes of ion migration and interface polarization caused by the electric field are consistent with the dynamic processes of microfluidic particle oscillation and cavitation collapse caused by ultrasonic vibration in spatial vectors. This avoids energy dispersion or cancellation that may occur due to cross or perpendicular directions. It is beneficial to transfer electric field energy more concentratedly to the solid-liquid interface region activated by ultrasonic cavitation, which can promote the generation of "electro-acoustic" coupling effect. This forms a combined force in reducing interfacial penetration resistance and driving the electrolyte to penetrate the pores in a directional manner, ultimately improving the overall wetting efficiency and uniformity of thick electrodes or high-density electrodes.

[0027] In the specific technical solution, the pulse waveform of the pulsed electric field is an exponentially decaying pulse waveform, the vibration frequency of the ultrasonic wave is 40kHz, and the amplitude is in the range of 0.03mm-0.08mm.

[0028] In addition, this application provides a method for impregnating a secondary battery cell, comprising: placing an electrode in an electrolyte in a receiving cavity; adjusting the air pressure, wherein the air pressure sequentially goes through a negative pressure stage, a normal pressure stage, and a positive pressure stage; making the receiving cavity negative pressure by evacuation, and simultaneously activating ultrasonic vibration at the start of the air pressure evacuation stage, with the pressurization stage overlapping with the peak period of ultrasonic vibration; triggering a pulsed electric field the instant the negative pressure changes to normal pressure, and the electric field effect lasts until the middle of the pressurization stage; wherein the pulse frequency of the electric field matches the resonance peak of the ultrasonic wave.

[0029] The secondary battery cell wetting method provided in this application solves the technical problems of slow electrolyte wetting and numerous residual bubbles in micropores in thick and highly dense electrodes by synergistically coupling three physical fields: a specific time-series gas pressure cycle, ultrasonic vibration, and a pulsed electric field. The electrode is placed in the electrolyte within a containment cavity to establish an initial solid-liquid interface. The containment cavity must be airtight to maintain the pressure environment required for subsequent gas pressure cycles. Gas pressure is adjusted, sequentially going through a negative pressure stage, a normal pressure stage, and a positive pressure stage. This three-stage gas pressure cycle provides the driving force required for wetting. Specifically, in the negative pressure stage, gas is removed from the electrode surface and larger pores by suction, reducing the overall resistance to subsequent liquid phase penetration. The subsequent positive pressure stage uses the pressure difference as the active driving force to pressurize the electrolyte into the deep pores of the electrode. This macroscopic pressure drive, in conjunction with the subsequent microscopic interaction field, constitutes a complete wetting drive chain from macroscopic to microscopic.

[0030] The containment cavity is brought under negative pressure through a evacuation process. Ultrasonic vibration is simultaneously activated at the start of the evacuation phase, with the pressurization phase overlapping with the peak ultrasonic vibration period. This step represents the first time that ultrasonic vibration and pneumatic circulation are coordinated in timing. Activating ultrasound during the evacuation phase utilizes the cavitation effect and mechanical vibration of ultrasound waves to pre-break and disturb the gas in the shallow pores of the electrodes, creating a smoother escape path for macroscopic evacuation. Overlapping the pressurization phase with the peak ultrasonic vibration period enhances the permeation effect under positive pressure. Ultrasonic vibration of the electrodes can generate instantaneous micro-gaps, creating a "pump-valve effect," which greatly accelerates the diffusion of electrolyte between and within the electrodes. The simultaneous application of pressurization and superimposed ultrasonic peak vibration synergistically utilizes the pressure-driven macroscopic flow and the ultrasonic-induced microscopic "pump-valve" effect to jointly promote the rapid filling of the electrolyte into the deeper pores.

[0031] The instantaneous transition from negative pressure to atmospheric pressure triggers a pulsed electric field, which continues until the mid-pressurization phase. This step introduces the pulsed electric field and defines its timing in relation to the pressure transition. The electric field is triggered at the instant of the transition from negative pressure to atmospheric pressure. During the negative pressure phase, most of the macroscopic gas has been eliminated, and the interface between the electrolyte and the electrode is initially formed but not yet fully spread. The instantaneously applied pulsed electric field actively reduces the interfacial energy of the electrolyte on the electrode solid surface through mechanisms such as electrocapillary effects, improving its wettability and creating interfacial conditions for the upcoming positive pressure permeation. Continuing the electric field until the mid-pressurization phase ensures that the interfacial energy remains optimized by the electric field during the critical initial stage of pressure-driven permeation, thus achieving a seamless transition from "interface optimization" to "driven filling."

[0032] Matching the pulse frequency of the electric field with the resonance peak of the ultrasound wave achieves acoustic-electric resonance. In the field of sono-electrochemistry, when the frequency of the input ultrasound matches the inherent frequency of the system, acoustic resonance can be generated at the electrode-solution interface, achieving energy focusing and enhancement, thereby more effectively influencing interfacial processes. Matching the fundamental frequency or main frequency component of the pulsed electric field with the mechanical resonance peak of the ultrasound transducer used (such as a 40kHz piezoelectric ceramic resonator) to excite and maintain a stable acoustic resonance state can not only improve the transmission efficiency of ultrasound energy, but also enable the polarization effect of the electric field on the interface and the mechanical disturbance of the ultrasound on the interface to work synergistically at the same frequency rhythm, producing a coupling effect of "1+1>2", thereby more effectively reducing penetration resistance at the microscale and improving the uniformity and thoroughness of wetting.

[0033] In the aforementioned secondary battery cell impregnation method, the pressure adjustment step is required to undergo multiple cycles. The repetition and reinforcement of this single three-stage cycle of "negative pressure-normal pressure-positive pressure" continuously overcomes capillary resistance and gas residue issues in pores of different sizes through cyclic pressure perturbation, thereby improving overall impregnation efficiency and consistency. A single pressure cycle may only effectively act on the electrode surface or larger pores. By subjecting the pressure adjustment step to multiple cycles, its technical effect lies primarily in providing intermittent driving force. Each negative pressure stage can re-extract gas that may have been compressed or blocked in deeper, more tortuous pores during the previous positive pressure permeation process; while the subsequent positive pressure stage utilizes the renewed pressure difference to drive the electrolyte to further permeate microscopic areas that were not fully filled in the previous cycle. The setting of multiple pressure cycles, combined with the continuous or periodic action of ultrasonic vibration and pulsed electric fields, can create a more lasting synergy. For example, the moment of transition from negative pressure to normal pressure during each pressure cycle can be designed as the trigger point for an electric field pulse, thereby repeatedly utilizing the electric field to reduce interfacial energy. Simultaneously, ultrasonic vibration can cover multiple pressure cycle stages, continuously breaking up newly formed or residual microbubbles. This multi-cycle, multi-physics-field coupled process design effectively shortens the wetting time, constructing a dynamic, iterative wetting propulsion mechanism. Combined with the temporal synergy of the electric and ultrasonic fields, it systematically addresses the challenges posed by the non-uniform pore structure within thick electrodes, gradually and thoroughly completing electrolyte filling from macroscopic to microscopic levels, ultimately achieving the technical effect of improved wetting speed and uniformity.

[0034] In the aforementioned secondary battery cell impregnation method, the specific pressure values ​​and holding times for each stage of the pressure adjustment step are quantitatively defined to match the impregnation pattern of the electrolyte in the porous electrode medium, and to achieve effective temporal coordination with ultrasonic and electric field techniques. The minimum pressure in the negative pressure stage is limited to less than -80 kPa to ensure sufficient pressure difference for effective removal of gas from the electrode surface and larger pores. The maximum pressure in the positive pressure stage is set to greater than 40 kPa to provide sufficient positive driving force after negative pressure venting, overcoming the capillary resistance and viscosity resistance encountered by the electrolyte as it moves through fine pores, driving it to penetrate deeper into the electrode. Regarding the holding time for each stage, the holding time in the negative pressure stage is limited to the range of 8 to 20 seconds to ensure sufficient time for gas in the electrode pores to escape under the pressure difference, while avoiding insufficient venting due to too short a time or reduced production efficiency due to too long a time. The brief holding period of 2 to 5 seconds at atmospheric pressure serves as a transition and balancing mechanism, allowing the pressure inside and outside the cavity to reach an instantaneous equilibrium after the transition from negative to atmospheric pressure. This creates stable pressure conditions for the subsequent coordinated step of "triggering the pulsed electric field the instantaneously after the transition from negative to atmospheric pressure," enabling the polarization effect of the electric field on the interface to proceed effectively without drastic pressure disturbances. Setting the holding time of the positive pressure phase within the range of 10 to 25 seconds ensures that, driven by the applied pressure difference, the electrolyte has sufficient time to penetrate and fill the deep pores of the electrode. Precise temporal coupling with the ultrasonic treatment period and the pulsed electric field triggering moment allows the triple effects of macroscopic pressure driving, microscopic cavitation cleaning, and interfacial energy reduction to act in an orderly and superimposed manner on the electrolyte wetting process.

[0035] In the aforementioned secondary battery cell impregnation device and method, the vibration direction of the ultrasonic waves generated by the ultrasonic control component and the electric field direction of the pulsed electric field applied by the electric field control component are both set to be parallel to the thickness direction of the electrode. This achieves synergy of multiple physical fields in spatial vectors, optimizing the energy transfer path and enhancing the comprehensive effect on the electrode-electrolyte interface. It ensures that the force vectors of the two physical fields acting on the interface region are superimposed, avoiding force dispersion or mutual cancellation that may occur due to intersecting or perpendicular directions. This allows energy to be transferred more concentratedly to the depth direction of the electrode pores. The improved wettability resulting from the reduction of interfacial energy by the electric field, combined with the microjets and "pump-valve" effect generated by ultrasonic vibration penetrating deep into the pores along the thickness direction, jointly drives the electrolyte to penetrate rapidly and uniformly along the path of least resistance, perpendicular to the electrode surface.

[0036] Furthermore, the pulsed electric field waveform provided by the electric field control component is specifically defined as an exponentially decaying pulse waveform. Its voltage decays exponentially with time after the initial peak, and its spectral characteristics show rich low-frequency and high-frequency components. This allows a single pulse to encompass a wider frequency range, potentially enabling broader interactions with polarized molecules or colloidal impurities of different sizes in the electrolyte. In the context of battery immersion, by controlling the parameters of the exponentially decaying waveform (such as peak voltage and decay constant), the polarization intensity and duration applied at the electrode-electrolyte interface can be adjusted, thereby optimizing the reduction effect on interface energy. Moreover, this waveform is often implemented in engineering using RC or RLC circuit discharge, and its mathematical description conforms to a typical exponential decay law, indicating high technological maturity.

[0037] In the secondary battery cell wetting method provided in this application, the peak voltage of the pulsed electric field is limited to the range of 2V to 6V, and the decay constant, which characterizes the pulse decay rate, is limited to the range of 0.05 seconds to 0.5 seconds. In the electrochemical system, the amplitude of the pulsed voltage applied to the working electrode needs to be sufficient to induce effective interfacial polarization to reduce the contact angle. However, excessively high voltage may lead to side reactions such as oxidative decomposition of the electrolyte. This application limits the peak voltage to 6V to ensure the electric field strength while controlling the voltage value near the electrochemical stability window of most organic electrolyte systems, thereby avoiding damage to the battery materials. On the other hand, the decay constant of the pulse (i.e., the time constant τ) directly determines the duration of the electric field energy acting on the interface. In this application, the decay constant is set between 0.05 seconds and 0.5 seconds. If the time is too short (much less than 0.05 seconds), the pulse effect may be too transient and insufficient to fully induce the recombination of the interfacial double layer and the directional alignment of electrolyte molecules. If the time is too long (more than 0.5 seconds), the pulse may approach the DC component, which not only reduces the advantages of the dynamic polarization characteristics of the pulse field, but may also increase unnecessary energy consumption and thermal effects due to the long-term application of voltage. Therefore, the above-mentioned range limitation of peak voltage and decay constant together ensures that the generated exponentially decaying pulse can provide a polarized electric field with appropriate intensity and controllable duration within a safe voltage threshold, thereby optimizing its effect on reducing interfacial energy and promoting electrolyte spreading.

[0038] The following will further introduce some specific implementation methods to provide a more detailed explanation of the technical solution of this application.

[0039] One specific embodiment of this application relates to an electrolyte wetting method for a 120 μm thick NCM811 positive electrode sheet. The method is as follows: First, the electrode sheet is fixed in a sealed wetting chamber, and electrolyte is injected so that the liquid level covers the electrode surface to a depth of approximately 5 mm. Then, the device parameters are adjusted, setting the peak voltage of the exponentially decaying pulse electric field to 3V and the decay constant to 0.1 seconds, the amplitude of the 40 kHz ultrasonic vibration to 0.05 mm, and the three-stage gas pressure cycle program to first apply a negative pressure of -90 kPa for 8 seconds, then switch to normal pressure and hold for 2 seconds, and finally apply a positive pressure of +50 kPa for 10 seconds. This gas pressure cycle is repeated three times. When the method is initiated, each component operates according to a preset coordinated timing sequence: ultrasonic vibration is synchronously activated at the start of the air extraction phase of the air pressure cycle; at the instant the air pressure changes from negative pressure to normal pressure, the exponentially decaying pulsed electric field is triggered, the pulse frequency of which matches the resonance peak of the ultrasonic vibration (matching frequency of 100Hz), and the electric field effect continues until the middle of the pressurization phase; simultaneously, the pressurization phase and the peak effect period of the ultrasonic vibration overlap. The technical effects obtained through the above implementation method include: after wetting, the contact angle of the electrolyte on the electrode surface decreases from the initial approximately 75° to below 25°; cross-sectional scanning electron microscopy reveals no residual bubbles in the electrode pores, and the electrolyte permeability reaches 98% at a depth of 50μm in the electrode; the total time for the entire wetting process is approximately 8 minutes. Compared to the conventional single-pressure wetting method used as a control (its wetting time is approximately 35 minutes, and its permeability is approximately 72%), this embodiment demonstrates an improvement in wetting efficiency.

[0040] To more clearly demonstrate the beneficial effects of the technical solution of this invention, two comparative examples were set up for comparative verification. Comparative Example 1 adopted a wetting method involving only air pressure circulation. Specifically, it involved conventional pressure wetting of the same NCM811 electrode without applying a pulsed electric field or ultrasonic vibration. The technical results were: the wetting time was up to 6 hours, the bubble residue rate in the electrode was 0.051, and the DC internal resistance of the battery after wetting was stable at 85 mΩ, with a fluctuation of approximately ±8 mΩ. Comparative Example 2 adopted a wetting method involving only ultrasonic vibration. Specifically, it involved applying 40 kHz ultrasound to the electrolyte and electrode without applying a pulsed electric field or air pressure circulation. The technical results were: the wetting time was 4.5 hours, the bubble residue rate was 0.038, and the DC internal resistance of the battery after wetting was stable at 45 mΩ, with a fluctuation of approximately ±5 mΩ. The aforementioned embodiments of the present invention achieve a final immersion time of approximately 8 minutes (approximately 0.13 hours), a bubble residue rate of only 0.004%, and a stable DC internal resistance of 22 mΩ with fluctuations controlled within ±0.5 mΩ. Comparison shows that this application, through the synergy of pulsed electric field, ultrasonic vibration, and pneumatic circulation, achieves comprehensive technical effects that cannot be achieved by a single method in significantly shortening immersion time, reducing bubble residue, and improving battery internal resistance consistency.

[0041] As described above, this application provides a secondary battery cell wetting device and method, which solves the technical problems of slow wetting speed, numerous micropore bubbles, and uncontrollable wetting process in thick and dense electrodes. The core is to construct a wetting system with multi-physics field temporal coordination and spatial coupling. The device includes a sealed cavity for accommodating the battery cell and electrolyte, a pressure adjustment component connected to the cavity, an electric field control component that provides a pulsed electric field to the cavity, and an ultrasonic control component that provides ultrasonic waves to the electrolyte. On this basis, a monitoring module that provides real-time feedback on the wetting completion through micro-pulse detection can also be integrated to achieve closed-loop process control.

[0042] The key to this method lies in the precise coordination of the timing and spatial direction of the effects of air pressure, ultrasound, and the pulsed electric field. In terms of timing, the method specifies that the air pressure must sequentially cycle through three stages: negative pressure, normal pressure, and positive pressure. Ultrasonic vibration is activated simultaneously during the pumping phase, and the electric field is triggered at the instant of transition from negative to normal pressure, ensuring that the pressurization phase overlaps with the peak ultrasound period. Spatially, both the direction of the ultrasonic vibration and the direction of the pulsed electric field are required to be parallel to the electrode thickness direction. Furthermore, the pulsed electric field uses an exponentially decaying waveform, and its pulse frequency must match the resonance peak of the ultrasound wave used.

[0043] Through the above design, gas pressure circulation provides macroscopic driving force to expel gas and drive permeation; ultrasound utilizes cavitation and acoustic flow effects to break up microbubbles and promote mass transfer; and pulsed electric field actively reduces solid-liquid interface energy and improves wettability through electrocapillary effect. The synergy of these three elements in frequency, timing, and spatial direction overcomes the limitations of single technologies, achieving synergistic wetting from macroscopic to microscopic levels. The introduction of a monitoring module allows for real-time control of the entire process based on changes in internal resistance, improving process consistency. It reduces the thick electrode wetting time from several hours in traditional processes to minutes; reduces the residual bubble rate in electrode pores to below 0.5%; and by improving wetting uniformity, it helps control the DC internal resistance fluctuation range of the cell within a narrower range (e.g., ±0.5mΩ), thus providing a foundation for improving battery capacity consistency and cycle life.

[0044] The above is only one specific implementation of this application, and any other improvements made based on the concept of this application shall be considered within the scope of protection of this application.

Claims

1. A device for impregnating secondary battery cells, characterized in that, It includes a receiving cavity, a pressure adjustment component, an electric field control component, and an ultrasonic control component, wherein the receiving cavity contains the battery cell and electrolyte; The air pressure adjustment component is connected to the receiving cavity and is used to adjust the air pressure inside the receiving cavity; The electric field control component provides a pulsed electric field to the cavity. The ultrasonic control component provides ultrasonic waves to the electrolyte; The pulse frequency of the provided electric field matches the resonance peak of the ultrasonic wave.

2. The secondary battery cell immersion device according to claim 1, characterized in that, It also includes a monitoring module, which provides real-time feedback on the completion of immersion through micro-pulse detection.

3. The secondary battery cell immersion device according to claim 1, characterized in that, The vibration direction of the ultrasonic wave is parallel to the electric field direction of the pulsed electric field.

4. The secondary battery cell immersion device according to claim 1, characterized in that, The pulse waveform of the pulsed electric field is an exponentially decaying pulse waveform, and the vibration frequency of the ultrasonic wave is 40kHz, with an amplitude in the range of 0.03mm-0.08mm.

5. A method for impregnating a secondary battery cell, characterized in that, include: Place the electrode in the electrolyte containing the cavity; The air pressure is adjusted, and the air pressure goes through the negative pressure stage, the normal pressure stage and the positive pressure stage in sequence. The cavity is made under negative pressure by evacuation. Ultrasonic vibration is started simultaneously at the beginning of the air pressure evacuation phase, and the pressurization phase overlaps with the peak period of ultrasonic vibration. The instantaneous change from negative pressure to normal pressure triggers a pulsed electric field, and the electric field effect lasts until the middle of the pressurization phase. In this process, the pulse frequency of the electric field matches the resonance peak of the ultrasonic wave.

6. The method for impregnating a secondary battery cell according to claim 5, characterized in that, The air pressure adjustment process involves multiple air pressure adjustment cycles.

7. The method for impregnating a secondary battery cell according to claim 6, characterized in that, The minimum air pressure during the negative pressure phase is less than -80 kPa, the maximum air pressure during the positive pressure phase is greater than 40 kPa, the duration of the negative pressure phase is in the range of 8s-20s, the duration of the normal pressure phase is in the range of 2s-5s, and the duration of the positive pressure phase is in the range of 10s-25s.

8. The method for impregnating a secondary battery cell according to claim 5, characterized in that, The vibration direction of the ultrasonic wave is parallel to the electric field direction of the pulsed electric field along the electrode thickness direction.

9. The method for impregnating a secondary battery cell according to claim 8, characterized in that, The pulse waveform of the pulsed electric field is an exponentially decaying pulse waveform, which decays exponentially over time after the initial peak.

10. The method for impregnating a secondary battery cell according to claim 9, characterized in that, The peak voltage of the pulsed electric field is in the range of 2V-6V, and the decay constant is in the range of 0.05s-0.5s.

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