Method of electrolyte impregnation of alkali metal ion battery cells, formation method and cell

Abstract

The present application relates to the technical field of lithium ion batteries, and specifically provides a method for infiltrating an electrolyte into an alkali metal ion battery cell, an infiltration formation method and an alkali metal ion battery cell. The method for infiltrating an electrolyte into a cell comprises: injecting an electrolyte into a cell, and infiltrating the cell; during the infiltration process, constant voltage charging at 0.2V-1V for a first preset time; wherein the cell comprises a plurality of cathode plates and a plurality of anode plates, and a diaphragm is arranged between adjacent cathode plates and anode plates. The present application adopts a constant voltage charging method for infiltration before the formation of the battery. In this way, an electric field is formed on the plates of the battery, promoting the formation of electric capillary tubes. The presence of electric capillary tubes can significantly accelerate the wetting process of the internal electrodes of high-energy batteries. Through this electric field construction infiltration technology, not only is the waiting time of the battery during the standing process significantly reduced, but also the infiltration effect between the electrodes and the electrolyte is greatly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of alkali metal ion battery, and particularly provides a method for infiltrating an electrolyte into an alkali metal ion battery cell, a formation method and an alkali metal ion battery cell. BACKGROUND

[0002] In alkali metal ion batteries, lithium ion batteries are widely used in portable, mobile and fixed energy storage devices due to their high energy conversion efficiency and high energy density. Currently, the battery industry is working to further improve the energy density of lithium ion batteries through new electrode materials or optimized battery design / manufacturing technology to meet the growing demand. For high-energy lithium ion batteries, large, thick and high-voltage electrodes are ideal because they help reduce the mass ratio and cost of inert materials. However, the accessibility and wettability of electrolyte in thick electrodes are emerging challenges. On the one hand, the increase in electrode area, thickness and density significantly increases the diffusion distance and resistance during electrolyte wetting. At the same time, the high packing density of the electrode not only increases the time required for battery filling, reducing the production rate of the battery, but also brings new challenges to the quality control of the battery. In addition, incompletely wetted electrodes can lead to high local current density around electrochemically active particles, inhibit the formation of uniform solid electrolyte interface (SEI), accelerate parasitic reactions and lithium precipitation, resulting in low capacity development, low coulombic efficiency, and rapid decay.

[0003] Therefore, it is necessary to explore how to improve the infiltration of the battery.

[0004] Currently, the commonly used methods for improving the infiltration of the battery are thermal static, adding wetting agents and changing the electrode structure, which can accelerate the filling and wetting of the battery. However, these methods are high in cost and complex in process, and are difficult to industrialize and mass-produce. SUMMARY

[0005] In order to overcome the above-mentioned defects, the present application provides a method for infiltrating an electrolyte into an alkali metal ion battery cell, a formation method and an alkali metal ion battery cell, which improves the electrolyte infiltration of the cell, improves lithium ion conduction and optimizes the performance of the cell.

[0006] In a first aspect, the present application provides a method for infiltrating an electrolyte into an alkali metal ion battery cell, comprising:

[0007] injecting the electrolyte into the cell to infiltrate the cell;

[0008] During the infiltration process, the first preset time is charged at a constant voltage of 0.2V-1V; wherein the cell comprises a plurality of cathode electrode sheets and a plurality of anode electrode sheets, and a separator is arranged between adjacent cathode electrode sheets and anode electrode sheets.

[0009] Furthermore, the first preset duration of constant voltage charging at 0.2-1V includes:

[0010] Charge at a constant voltage of 0.2-1V for 1-3 hours.

[0011] Furthermore, during the constant voltage charging process, a vacuum is evacuated inside the battery cell.

[0012] Furthermore, when evacuating the cell, the vacuum level inside the cell is maintained at -20KPa to -50KPa.

[0013] Furthermore, during constant voltage charging, the lower cutoff current is set to 0-1A.

[0014] Furthermore, prior to the constant voltage charging step at 0.2V-1V, the method further includes: injecting electrolyte into the battery cell and then allowing it to stand for 1.5-2 hours.

[0015] In a second aspect, the present invention provides a method for impregnating and forming a battery cell, comprising:

[0016] The battery cell is wetted using the first method;

[0017] The immersed battery cells are then subjected to formation.

[0018] Furthermore, the formation of the impregnated battery cell includes:

[0019] The immersed battery cells are charged using a charging current of 0.1C-0.2C.

[0020] Furthermore, the immersed battery cells are charged multiple times using a charging current of 0.1C-0.2C, with each charging session lasting 7-30 minutes.

[0021] Furthermore, a resting time is set after each charge, wherein the resting time is 4-8 minutes.

[0022] Furthermore, the charging cycle is 4-10 times.

[0023] Furthermore, the formation process includes:

[0024] First, the immersed battery cell is charged multiple times using a charging current of the first preset rate.

[0025] Then, the charging current at the second preset rate is used to charge the device multiple times.

[0026] Wherein, the second preset multiplier is greater than the first preset multiplier. Further, the formation process includes:

[0027] The wetted battery cells were charged at a constant current of 0.1C for 7 minutes.

[0028] Let stand for 5 minutes;

[0029] Charge at a constant current of 0.1C for 23 minutes;

[0030] Let stand for 5 minutes;

[0031] Charge at a constant current of 0.1C for 18 minutes;

[0032] Let stand for 5 minutes;

[0033] Charge at a constant current of 0.1C for 18 minutes;

[0034] Let stand for 5 minutes;

[0035] Charge at a constant current of 0.1C for 24 minutes;

[0036] Let stand for 5 minutes;

[0037] Charge at a constant current of 0.2C for 24 minutes;

[0038] Let stand for 5 minutes;

[0039] Charge at a constant current of 0.2C for 30 minutes;

[0040] Let stand for 5 minutes.

[0041] In a third aspect, the present invention provides an alkali metal ion battery cell obtained by the impregnation formation method described in the second aspect.

[0042] Furthermore, the alkali metal ion battery cell is a lithium-ion battery cell.

[0043] Furthermore, the active material of the anode electrode is lithium iron phosphate.

[0044] The above-described technical solutions of the present invention have at least one or more of the following beneficial effects:

[0045] In the technical solution of this invention, constant voltage charging is applied before the battery formation process begins to promote electrolyte wetting. This creates an electric field on the battery electrodes, thereby promoting the formation of electrocapillaries. The presence of these electrocapillaries significantly accelerates the wetting process of the internal electrodes of the high-energy battery. This application of electric field-based permeation technology not only significantly reduces the waiting time during battery resting but also greatly improves the wetting effect between the electrodes and the electrolyte. The implementation of this technology significantly improves the condition of the electrodes after formation and reduces defects, thus contributing to increased battery production efficiency, as well as improved overall battery performance and lifespan. Attached Figure Description

[0046] The disclosure of this invention will become more readily understood with reference to the accompanying drawings. It will be readily understood by those skilled in the art that these drawings are for illustrative purposes only and are not intended to limit the scope of protection of this invention. Furthermore, similar numbers in the drawings are used to denote similar components, wherein:

[0047] Figure 1 This is a schematic flowchart of the main steps of an electrolyte-wetting method for a battery cell according to an embodiment of the present invention;

[0048] Figure 2 This is a schematic diagram of the electrode plates after disassembly of the battery cell according to Comparative Example 1 of the present invention;

[0049] Figure 3 This is a schematic diagram of the electrode plates after disassembly of the battery cell according to Embodiment 1 of the present invention;

[0050] Figure 4 This is a schematic diagram of the electrode plates after disassembly of the battery cell according to Embodiment 2 of the present invention;

[0051] Figure 5 This is a schematic diagram of the electrode plates after disassembly of the battery cell according to Embodiment 3 of the present invention;

[0052] Figure 6 This is a schematic diagram of the electrode plates after the battery cell is disassembled according to Embodiment 4 of the present invention. Detailed Implementation

[0053] Some embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0054] This invention provides a method for impregnating an alkali metal ion battery cell with an electrolyte, referring to... Figure 1 ,include:

[0055] S1, inject electrolyte into the battery cell to wet the battery cell;

[0056] S2, during the immersion process, constant voltage charging at 0.2V-1V for the first preset time.

[0057] The battery cell mentioned in step S1 includes several cathode plates and several anode plates, with a separator between adjacent cathode plates and anode plates.

[0058] Cathode, anode, and separator can be used to form a battery cell through lamination or winding processes.

[0059] In traditional battery cell manufacturing, after the electrolyte injection step, the cell typically undergoes a relatively long settling period. The main purpose of this stage is to allow the electrolyte to fully wet the internal structure of the cell. However, this settling process is not only time-consuming, but its wetting effect is often less than ideal. Because the electrolyte fails to fully wet the cell's interior, this negatively impacts the overall performance of the battery, consequently affecting its lifespan and efficiency.

[0060] This invention proposes a novel electrolyte-wetting technique for battery cells, aiming to improve the wetting effect of the electrolyte and optimize battery performance and efficiency. Specifically, after single-cell electrolyte injection, the battery cell is charged within a specific voltage range. In this way, the invention adds a constant-voltage charging step before cell formation. This process provides an electric field environment for the battery cell, thereby forming an electrocapillary phenomenon on the battery electrodes. These electrocapillaries significantly accelerate the wetting process of the internal electrodes of high-energy batteries, thereby improving the overall performance and lifespan of the battery. Through this method, the electrochemical reaction efficiency of the battery is improved, and the charge-discharge performance of the battery is also significantly enhanced.

[0061] This invention enables the electrolyte to penetrate the cell more quickly, significantly improving the electrolyte's wetting effect on the electrodes and enhancing battery performance. This improvement not only increases production efficiency but may also reduce production costs, ultimately bringing significant economic benefits to the cell manufacturing industry.

[0062] Compared to existing methods such as thermal static electricity, adding wetting agents, and modifying electrode structure, this invention demonstrates significant advantages in terms of compatibility with existing manufacturing processes. Specifically:

[0063] 1. This invention does not introduce more stringent and demanding process control parameters, such as temperature. Although high temperature can promote electrolyte penetration to some extent, changes in temperature will greatly increase energy consumption during industrialization and significantly increase the difficulty of controlling the static production area.

[0064] 2. This invention does not introduce any new electrolyte components, thus avoiding changes to the electrolyte system. This is because new components may negatively impact battery performance, thereby affecting the overall performance and reliability of the battery. Therefore, this invention maintains the stability of the electrolyte system.

[0065] 3. This invention does not change the electrode structure. Changing the electrode structure would require adaptive adjustments to other processes, such as the electrode slicing method and the electrode assembly process. These changes involve modifications to design processes, tooling, and equipment, significantly impacting conventional production lines.

[0066] This invention adds a specific charging procedure before the formation charging process. This procedure is highly compatible with existing processes and optimizes battery wettability while improving battery production efficiency. In this way, the invention not only improves electrolyte wettability, thereby enhancing overall battery performance and reliability, but also ensures production efficiency.

[0067] In one embodiment, step S2, the preset duration of constant voltage charging at 0.2-1V includes: constant voltage charging for 1-3 hours at 0.2-1V.

[0068] A specific electric field can be constructed by charging at a specific pressure of 0.2-1V for 1-3 hours.

[0069] When an electric field is applied to the electrode, it affects the interaction between the electrode and the electrolyte interface and the charge distribution, thereby creating electrocapillaries. This makes it easier for the electrolyte to wet the electrode surface. The application of the electric field reduces the interfacial tension, allowing the electrolyte to spread more evenly on the electrode surface. This helps the electrolyte penetrate deeper into the pores of the electrode, thus improving the wetting effect.

[0070] This invention establishes an electric field through constant-voltage charging, enabling the electrolyte to spread and penetrate more evenly onto the electrode surface. This process is significant for improving battery performance and lifespan.

[0071] In one embodiment, during step S2, when the constant voltage charging is performed, a vacuum is drawn inside the battery cell.

[0072] In one specific embodiment, when the battery cell is evacuated, the vacuum level inside the cell is maintained within the range of -20 kPa to -50 kPa. This effectively controls the internal gas pressure of the battery cell.

[0073] This invention adds a constant-voltage charging step before the cell formation process. This process provides the necessary electric field for the battery, enabling the formation of electrocapillaries on the positive and negative electrode plates. The presence of these electrocapillaries significantly accelerates the wetting process of the internal electrodes. The formation of electrocapillaries is due to the electric field causing liquid molecules on the electrode surface to rearrange under the influence of the electric field force, thereby forming a special capillary structure. The presence of this structure effectively promotes the diffusion and wetting of the electrolyte on the electrode surface.

[0074] After the cell is filled with electrolyte, a vacuum is created using negative pressure to further expel gas from the cell interior, as well as from the pores in the positive and negative electrode plates and the separator. This process is crucial for electrolyte wetting. When the gas is effectively expelled, the electrolyte can more easily fill these pores, ensuring sufficient contact between the electrolyte and the electrode materials. This sufficient contact is a prerequisite for the battery to perform optimally.

[0075] The combination and promotion of negative pressure vacuum and the electrocapillary formed by the electric field can greatly improve the wetting efficiency of the electrolyte.

[0076] In one embodiment, during constant voltage charging, the lower cutoff current is set to 0-1A.

[0077] In one embodiment, prior to the constant voltage charging step at 0.2V-1V, the method further includes:

[0078] After injecting the electrolyte into the battery cell, let it stand for 1.5-2 hours.

[0079] The room temperature is sufficient for standing; a high-temperature environment is not required.

[0080] After standing for 1.5-2 hours, charge at a constant voltage of 0.2V-1V for a first preset time to allow the battery cell to be immersed in the electrolyte.

[0081] Charging the battery cell with appropriate pre-wetting promotes and optimizes the establishment of the electric field and the formation of electrocapillaries. Proper wetting reduces the interfacial tension between the electrolyte and the electrode. This facilitates the electrolyte's subsequent penetration into the micropores of the electrode during charging, thereby increasing the penetration depth. Appropriately wetted electrode surfaces provide favorable conditions for electrocapillary formation, allowing the electrolyte to adhere more tightly to the electrode surface and form a stable capillary structure under the influence of the electric field.

[0082] The present invention also provides a method for impregnating and forming a battery cell, comprising:

[0083] The battery cell is impregnated using the method described above;

[0084] The immersed battery cells are then subjected to formation.

[0085] First, this invention proposes a unique charging-enhanced permeation method that ensures the battery cell is adequately wetted by forming electrocapillaries. This adequate wettability is fundamental to subsequent formation processes, as optimal performance can only be achieved when the cell is fully immersed in the electrolyte. The degree of wettability significantly impacts battery performance. For example, poor electrolyte wettability lengthens ion transport paths, hindering lithium ion shuttle movement between the positive and negative electrodes, thus affecting charge transfer efficiency. Uneven wettability leads to uneven current density distribution, resulting in an unstable electrolyte interphase (SEI) film and triggering a series of safety issues.

[0086] Specifically, the charging method of this invention, by precisely controlling the charging voltage and duration, allows the electrolyte to fully penetrate the cell, thereby achieving uniform wetting. This uniform wetting not only helps improve the battery's charging and discharging efficiency but also significantly enhances its cycle life and safety. In practical applications, this method can effectively avoid battery performance degradation and safety hazards caused by insufficient electrolyte wetting.

[0087] After the battery cell is fully immersed, the next step is the formation process. This process involves a series of charge-discharge cycles inside the cell to activate the active materials, enabling it to perform normal charge and discharge operations. This process has a significant impact on the battery's performance and lifespan.

[0088] In one embodiment, the formation of the impregnated battery cell includes:

[0089] The immersed battery cells are charged using a charging current of 0.1C-0.2C.

[0090] In one embodiment, the immersed battery cell is charged multiple times with a charging current of 0.1C-0.2C, and each charging session lasts 7-30 minutes.

[0091] Constant current charging is used each time it is charged.

[0092] In one embodiment, a resting time is set after each charge, wherein the resting time is 4-8 minutes.

[0093] In one embodiment, a resting time is set after each charge, wherein the resting time is 5 minutes.

[0094] In one embodiment, the number of charging cycles is 4-10.

[0095] In one embodiment, the formation process includes:

[0096] First, the immersed battery cells are charged multiple times using a charging current of the first preset rate.

[0097] Then, the battery cell, which has been charged at the first preset rate, is charged multiple times using a second preset rate charging current.

[0098] Wherein, the second preset multiplier is greater than the first preset multiplier.

[0099] In one embodiment, the formation process includes:

[0100] The wetted battery cells were charged at a constant current of 0.1C for 7 minutes.

[0101] Let stand for 5 minutes;

[0102] Charge at a constant current of 0.1C for 23 minutes;

[0103] Let stand for 5 minutes;

[0104] Charge at a constant current of 0.1C for 18 minutes;

[0105] Let stand for 5 minutes;

[0106] Charge at a constant current of 0.1C for 18 minutes;

[0107] Let stand for 5 minutes;

[0108] Charge at a constant current of 0.1C for 24 minutes;

[0109] Let stand for 5 minutes;

[0110] Charge at a constant current of 0.2C for 24 minutes;

[0111] Let stand for 5 minutes;

[0112] Charge at a constant current of 0.2C for 30 minutes;

[0113] Let stand for 5 minutes.

[0114] The present invention also provides an alkali metal ion battery cell, which is obtained by the impregnation formation method described above.

[0115] In one embodiment, the alkali metal ion battery cell is a lithium-ion battery cell.

[0116] The lithium-ion batteries prepared using the immersion formation method proposed in this invention exhibit extremely high compatibility with existing production lines. This high compatibility means that the method can be easily integrated into existing production processes without requiring large-scale modifications or replacements of existing equipment. Therefore, this method not only facilitates the industrialization of lithium-ion batteries but also significantly lowers the barriers and costs of promoting new technologies. This accelerates the improvement of lithium-ion battery production efficiency and quality, further driving technological progress and market expansion across the entire industry.

[0117] In one embodiment, the active material of the anode electrode is lithium iron phosphate.

[0118] The positive electrode material of the lithium-ion battery cell can be the common lithium iron phosphate material. The negative electrode material can be the common graphite material. The separator can be the common polyethylene (PE) and polypropylene (PP), or a composite membrane of these two materials, such as PE / PP, PP / PE / PP, etc.

[0119] The following describes the preparation of lithium-ion battery cells using immersion formation methods with different parameters. After formation, the cells are disassembled to observe the state of the electrodes.

[0120] Comparative Example 1

[0121] Let the 2Ah lithium-ion battery cell that has just finished being filled with electrolyte stand at 25°C for 2 hours.

[0122] After the settling period, a formation process is performed, which includes the following steps:

[0123] The wetted battery cells were charged at a constant current of 0.1C for 7 minutes.

[0124] Let stand for 5 minutes;

[0125] Charge at a constant current of 0.1C for 23 minutes;

[0126] Let stand for 5 minutes;

[0127] Charge at a constant current of 0.1C for 18 minutes;

[0128] Let stand for 5 minutes;

[0129] Charge at a constant current of 0.1C for 18 minutes;

[0130] Let stand for 5 minutes;

[0131] Charge at a constant current of 0.1C for 24 minutes;

[0132] Let stand for 5 minutes;

[0133] Charge at a constant current of 0.2C for 24 minutes;

[0134] Let stand for 5 minutes;

[0135] Charge at a constant current of 0.2C for 30 minutes;

[0136] Let stand for 5 minutes.

[0137] After formation, the battery cell is charged to 3.65V at a constant current of 0.5C.

[0138] Disassemble the fully charged battery cells, referring to...Figure 2 Observation of the electrode state revealed that after formation, the fully charged interface had a large number of purple spots and dark lines in the middle, accompanied by lithium plating, indicating that the electrolyte was not wetted enough, making it difficult for lithium to be intercalated locally, thus causing lithium plating and dark lines.

[0139] Comparative Example 2

[0140] The only difference between Comparative Example 2 and Comparative Example 1 is that the standing time after injection is 6 hours.

[0141] Disassembling the fully charged battery cell and observing the electrode condition revealed that the fully charged interface was in good condition after formation, with no purple spots, some dark lines, and no lithium plating. The presence of dark lines could lead to lithium plating during subsequent battery cycles, posing a safety risk.

[0142] Comparative Example 3

[0143] The only difference between Comparative Example 3 and Comparative Example 1 is that the standing time after injection is 12 hours.

[0144] Disassembling the fully charged battery cell and observing the electrode condition revealed that the fully charged interface was in good condition after formation, with no purple spots, dark lines, or lithium plating.

[0145] Example 1

[0146] The 2Ah lithium-ion battery cell that has just finished being filled with electrolyte was charged at a constant voltage of 0.2V for 2 hours at 25℃, with the cutoff lower limit current set to 0A.

[0147] After constant voltage charging is completed, formation is performed, and the formation steps are the same as those in Comparative Example 1.

[0148] Disassemble the fully charged battery cells, referring to... Figure 3 Observation of the negative electrode sheet revealed that the purple spots and dark lines at the fully charged interface were reduced compared to comparative examples 1 and 2, and there was no lithium plating, indicating that the wetting was improved and the cell performance was enhanced.

[0149] Example 2

[0150] The 2Ah lithium-ion battery cell that has just finished being filled with electrolyte was charged at a constant voltage of 0.3V for 2 hours at 25℃, with the cutoff lower limit current set to 0A.

[0151] After constant voltage charging is completed, formation is performed, and the formation steps are the same as those in Comparative Example 1.

[0152] Disassemble the fully charged battery cells, referring to... Figure 4 Observation of the negative electrode sheet revealed that after formation, the purple spots and dark lines at the full charge interface were reduced compared to Example 1, and there was no lithium plating, indicating that wetting was improved and the cell performance was improved.

[0153] Example 3

[0154] The 2Ah lithium-ion battery cell that has just finished being filled with electrolyte was charged at 0.5V constant voltage for 2 hours at 25℃, with the cutoff lower limit current set to 0A.

[0155] After constant voltage charging is completed, formation is performed, and the formation steps are the same as those in Comparative Example 1.

[0156] Disassemble the fully charged battery cells, referring to... Figure 5 Observation of the negative electrode sheet revealed that after formation, the purple spots and dark lines at the full charge interface were reduced compared to Example 2, and there was no lithium plating, indicating that wetting was improved and the cell performance was improved.

[0157] Example 4

[0158] The 2Ah lithium-ion battery cell that has just finished being filled with electrolyte was charged at 1V constant voltage for 2 hours at 25℃, with the cutoff lower limit current set to 0A.

[0159] After constant voltage charging is completed, formation is performed, and the formation steps are the same as those in Comparative Example 1.

[0160] Disassemble the fully charged battery cells, referring to... Figure 6 Observation of the negative electrode sheet revealed that after formation, there were a few or trace purple spots on the fully charged interface, the dark pattern in the middle disappeared, and there was no lithium plating, indicating that the wetting was improved and the cell performance was improved.

[0161] Comparative Example 4

[0162] The 2Ah lithium-ion battery cell that has just finished being filled with electrolyte was charged at a constant voltage of 1.5V for 2 hours at 25℃, with the cutoff lower limit current set to 0A.

[0163] After constant voltage charging is completed, formation is performed, and the formation steps are the same as those in Comparative Example 1.

[0164] Disassembling the fully charged battery cell and observing the state of the negative electrode revealed purple spots and lithium plating at the fully charged interface. This was mainly because as the voltage increased, the constant current charging effect increased, and the decomposition of the electrolyte produced gas, leading to a deterioration in the constant voltage effect.

[0165] Example 5

[0166] The 2Ah lithium-ion battery cell that has just finished being filled with electrolyte was charged at a constant voltage of 0.7V for 3 hours at 25℃, with the lower limit current set at 1A.

[0167] After constant voltage charging is completed, formation is performed, and the formation steps are the same as those in Comparative Example 1.

[0168] Disassembling the fully charged battery cell and observing the state of the negative electrode revealed that there were a few purple spots on the fully charged interface, but no obvious dark lines or lithium plating.

[0169] Example 6

[0170] The lithium-ion battery cell that has just finished being filled with electrolyte was charged at a constant voltage of 0.8V for 1 hour at 25°C, with the lower limit current set at 0.5A.

[0171] After constant voltage charging is completed, formation is performed, and the formation steps are the same as those in Comparative Example 1.

[0172] Disassembling the fully charged battery cell and observing the electrode condition revealed that there were a few purple spots on the fully charged interface, but no obvious dark lines or lithium plating.

[0173] Example 7

[0174] The 2Ah lithium-ion battery cell, which has just finished being filled with electrolyte, is charged at a constant voltage of 0.3V for 2 hours at 25°C. During the vacuuming process inside the cell, the vacuum level is maintained at -30KPa. The lower cutoff current is set to 0A.

[0175] After constant voltage charging is completed, formation is performed, and the formation steps are the same as those in Comparative Example 1.

[0176] After the battery cell was fully charged, the electrode condition was observed. It was found that the purple spots and dark lines at the full charge interface after formation were reduced compared with Example 2, and there was no lithium plating, indicating that the wetting was improved and the battery cell performance was improved.

[0177] Example 8

[0178] The 2Ah lithium-ion battery cell, which has just finished being filled with electrolyte, is charged at a constant voltage of 0.3V for 2 hours at 25°C. During the vacuuming process, the vacuum level inside the cell is maintained at -20KPa. The lower cutoff current is set to 0A.

[0179] After constant voltage charging is completed, formation is performed, and the formation steps are the same as those in Comparative Example 1.

[0180] After the battery cell was fully charged, the electrode condition was observed. It was found that the purple spots and dark lines at the full charge interface after formation were reduced compared with Example 2, and there was no lithium plating, indicating that the wetting was improved and the battery cell performance was improved.

[0181] Example 9

[0182] The 2Ah lithium-ion battery cell, which has just finished being filled with electrolyte, is charged at a constant voltage of 0.3V for 2 hours at 25°C. During the vacuuming process inside the cell, the vacuum level is maintained at -50KPa. The lower cutoff current is set to 0A.

[0183] After constant voltage charging is completed, formation is performed, and the formation steps are the same as those in Comparative Example 1.

[0184] After the battery cell was fully charged, the electrode condition was observed. It was found that the purple spots and dark lines at the full charge interface after formation were reduced compared with Example 2, and there was no lithium plating, indicating that the wetting was improved and the battery cell performance was improved.

[0185] Example 10

[0186] The 2Ah lithium-ion battery cell, which has just finished being filled with electrolyte, is charged at a constant voltage of 1V for 1.5 hours at 25°C. During the vacuuming process inside the cell, the vacuum level is maintained at -30KPa. The lower cutoff current is set to 0A.

[0187] After constant voltage charging is completed, formation is performed, and the formation steps are the same as those in Comparative Example 1.

[0188] After the battery cell was fully charged, the electrode condition was observed. It was found that the purple spots and dark lines at the full-charge interface disappeared after the formation was completed, and there was no lithium plating, indicating that the wetting was improved and the battery cell performance was improved.

[0189] Example 11

[0190] After the 2Ah lithium-ion battery cell has been filled with electrolyte, let it stand for 2 hours, then charge it at a constant voltage of 0.8V for 1.5 hours at 25℃. Set the lower limit current to 0A.

[0191] After constant voltage charging is completed, formation is performed, and the formation steps are the same as those in Comparative Example 1.

[0192] After the battery cell was fully charged, the electrode condition was observed. It was found that the purple spots and dark lines at the full-charge interface disappeared after the formation was completed, and there was no lithium plating, indicating that the wetting was improved and the battery cell performance was improved.

[0193] The main parameters and electrode formation states of Examples 1-11 and Comparative Examples 1-4 are shown in Table 1.

[0194] Table 1. Main parameters and electrode states after formation for Examples 1-11 and Comparative Examples 1-4.

[0195]

[0196]

[0197] In implementing the technical solution of this invention, a constant voltage charging process is set before the battery formation process begins to promote electrolyte wetting. This creates an electric field on the battery electrodes, thereby promoting the formation of electrocapillaries. The presence of electrocapillaries significantly accelerates the internal wetting process of high-energy-density batteries. By applying this electric field-driven penetration technique, not only is the waiting time during battery resting significantly reduced, but the wetting effect between the electrodes and the electrolyte is also greatly improved.

[0198] Allowing the battery to rest briefly before constant voltage charging or adding appropriate vacuuming during constant voltage charging can promote the formation of the electric field on the battery electrodes, significantly improving the state of the electrodes after formation. Implementing this technology significantly improves the state of the electrodes after formation and reduces defects, thus contributing to increased battery production efficiency, overall battery performance, and lifespan.

[0199] The process control of this invention is simple. Constant voltage charging at room temperature can promote electrolyte wetting. After the constant voltage charging for promoting wetting is completed, formation can begin directly without standing, which greatly improves production efficiency.

[0200] It should be noted that although the steps in the above embodiments are described in a specific order, those skilled in the art will understand that in order to achieve the effects of the present invention, different steps do not necessarily have to be executed in such an order. They can be executed simultaneously (in parallel) or in other orders, and these variations are all within the scope of protection of the present invention.

[0201] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A method for impregnating an alkali metal ion battery cell with an electrolyte, characterized in that, include: Electrolyte is injected into the battery cell to wet it; During the immersion process, the battery cell is charged at a constant voltage of 0.2V-1V for a first preset time; wherein, the battery cell includes several cathode plates and several anode plates, and a diaphragm is provided between adjacent cathode plates and anode plates; The first preset duration of constant voltage charging at 0.2-1V includes: constant voltage charging for 1-3 hours at 0.2-1V; During constant voltage charging, the lower cutoff current is set to 0-1A.

2. The method according to claim 1, characterized in that, During constant voltage charging, a vacuum is drawn inside the battery cell.

3. The method according to claim 2, characterized in that, When evacuating the cell, maintain the vacuum level inside the cell at -20 kPa to -50 kPa.

4. The method according to claim 1, characterized in that, Prior to the constant voltage charging step at 0.2V-1V, the method further includes: After injecting the electrolyte into the battery cell, let it stand for 1.5-2 hours.

5. A method for impregnating and forming a battery cell, characterized in that, include: The battery cell is impregnated using any one of claims 1-4; The immersed battery cells are then subjected to formation.

6. The method according to claim 5, characterized in that, The formation process for the impregnated battery cells includes: The immersed battery cells are charged using a charging current of 0.1C-0.2C.

7. The method according to claim 6, characterized in that, The immersed battery cells are charged multiple times using a charging current of 0.1C-0.2C, with each charging session lasting 7-30 minutes.

8. The method according to claim 7, characterized in that, Set a resting time after each charge, wherein the resting time is 4-8 minutes.

9. The method according to claim 7, characterized in that, It can be charged 4-10 times.

10. The method according to any one of claims 5-9, characterized in that, The formation process includes: First, the immersed battery cell is charged multiple times using a charging current of the first preset rate. Then, the charging current at the second preset rate is used to charge the device multiple times. Wherein, the second preset multiplier is greater than the first preset multiplier.

11. The method according to claim 10, characterized in that, The formation process includes: The wetted battery cells were charged at a constant current of 0.1C for 7 minutes. Let stand for 5 minutes; Charge at a constant current of 0.1C for 23 minutes; Let stand for 5 minutes; Charge at a constant current of 0.1C for 18 minutes; Let stand for 5 minutes; Charge at a constant current of 0.1C for 18 minutes; Let stand for 5 minutes; Charge at a constant current of 0.1C for 24 minutes; Let stand for 5 minutes; Charge at a constant current of 0.2C for 24 minutes; Let stand for 5 minutes; Charge at a constant current of 0.2C for 30 minutes; Let stand for 5 minutes.

12. An alkali metal ion battery cell, characterized in that, It is obtained by the impregnation formation method as described in any one of claims 5 to 11.

13. The battery cell according to claim 12, characterized in that, The alkali metal ion battery cell is a lithium-ion battery cell.

14. The battery cell according to claim 13, characterized in that, The active material of the anode electrode is lithium iron phosphate.

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