Method for infiltrating alkali metal ion battery cell with electrolyte, formation method and battery cell

Abstract

The invention relates to the technical field of lithium ion batteries, and particularly provides a method for infiltrating an alkali metal ion battery cell with an electrolyte, an infiltration formation method and the alkali metal ion battery cell. The method for infiltrating the battery cell with the electrolyte comprises the following steps: injecting the electrolyte into the battery cell, and infiltrating the battery cell, in the infiltration process, constant-voltage charging is carried out for a first preset duration under 0.2-1 V; wherein the battery cell comprises a plurality of cathode pole pieces and a plurality of anode pole pieces, and a diaphragm is arranged between the adjacent cathode pole piece and anode pole piece. Before the battery formation process, a constant-voltage charging mode is adopted for infiltration. Therefore, an electric field is formed on the pole piece of the battery to promote the formation of an electrocapillary. The presence of the electrocapillary can significantly accelerate the wetting process of the internal electrode of the high-energy battery. Through the construction of the electric field infiltration promotion technology, the waiting time of the battery in the standing process is remarkably shortened, and the infiltration effect between the electrode and the electrolyte is greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of alkali metal ion batteries, and specifically provides a method for infiltrating an alkali metal ion battery cell with an electrolyte, a formation method and an alkali metal ion battery cell. Background Art

[0002] Among alkali metal ion batteries, lithium-ion batteries are widely used in portable, mobile and stationary 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 electrolytes 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 the electrolyte wetting process. At the same time, the high packing density of electrodes not only increases the time required for battery filling and reduces the battery productivity, but also brings new challenges to battery quality control. In addition, incompletely wetted electrodes can lead to high local current density around electrochemically active particles, inhibit the formation of a uniform solid electrolyte interface (SEI), accelerate parasitic reactions and lithium precipitation, and thus lead to low capacity utilization, low Coulombic efficiency, and rapid decay.

[0003] Therefore, it is necessary to explore how to improve the wetting of batteries.

[0004] At present, the commonly used methods to improve battery wetting are heat quenching, adding wetting agents and changing the electrode structure, which can accelerate the filling and wetting of the battery. However, these methods are costly and complex, and are difficult to promote in industrial mass production. Summary of the invention

[0005] In order to overcome the above defects, the present invention proposes a method for electrolyte infiltration of alkali metal ion battery cells, a formation method and an alkali metal ion battery cell, which improves lithium ion conduction and optimizes battery cell performance by improving the electrolyte wettability of the battery cell.

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

[0007] Injecting electrolyte into the battery cell to wet the battery cell;

[0008] During the infiltration process, constant voltage charging is performed at 0.2V-1V for a first preset time; wherein, the battery cell includes a plurality of cathode plates and a plurality of anode plates, and a diaphragm is provided between adjacent cathode plates and anode plates.

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

[0010] At 0.2-1V, constant voltage charging for 1-3 hours.

[0011] Furthermore, during the constant voltage charging, the battery cell is vacuumed.

[0012] Furthermore, when the battery cell is evacuated, the vacuum degree in the battery cell is maintained at -20 KPa to -50 KPa.

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

[0014] Furthermore, before the step of constant voltage charging at 0.2V-1V, the method further comprises: injecting electrolyte into the battery cell and leaving it to stand for 1.5-2h.

[0015] In a second aspect, the present invention provides a method for infiltration formation of a battery cell, comprising:

[0016] The battery cell is wetted by the method of the first aspect;

[0017] The soaked battery cells are then formed.

[0018] Further, the forming of the soaked battery cell comprises:

[0019] The soaked battery cell is charged with a charging current of 0.1C-0.2C.

[0020] Furthermore, the soaked battery cell is charged multiple times with a charging current of 0.1C-0.2C, and each charging time is 7-30 minutes.

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

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

[0023] Further, the formation process comprises:

[0024] Firstly, the soaked battery cell is charged multiple times with a charging current of a first preset rate;

[0025] Then, a charging current of a second preset rate is used to perform multiple charging operations;

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

[0027] The soaked cells were charged at a constant current of 0.1C for 7 min.

[0028] Let stand for 5 minutes;

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

[0030] Let stand for 5 minutes;

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

[0032] Let stand for 5 minutes;

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

[0034] Let stand for 5 minutes;

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

[0036] Let stand for 5 minutes;

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

[0038] Let stand for 5 minutes;

[0039] Charge at 0.2C constant current 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 infiltration formation method as 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 one or more technical solutions of the present invention have at least one or more of the following beneficial effects:

[0045] In the technical solution of the present invention, before the battery formation process begins, constant voltage charging is set to promote electrolyte infiltration. In this way, an electric field is formed on the pole piece of the battery, thereby promoting the formation of electric capillaries. The presence of electric capillaries can significantly accelerate the wetting process of the internal electrodes of high-energy batteries. Through the application of this electric field-promoted infiltration technology, not only the waiting time of the battery during the static process is significantly reduced, but also the infiltration effect between the electrode and the electrolyte is greatly improved. The implementation of this technology has significantly improved the state of the pole piece after formation and reduced defects, which helps to improve the production efficiency of the battery, and also helps to improve the overall performance and life of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The disclosure of the present invention will become more easily understood with reference to the accompanying drawings. It is easy for those skilled in the art to understand that these drawings are only for illustrative purposes and are not intended to limit the scope of protection of the present invention. In addition, similar numbers in the figures are used to represent similar components, among which:

[0047] Figure 1 This is a schematic flow chart of the main steps of a method for infiltrating a battery cell with an electrolyte according to an embodiment of the present invention;

[0048] Figure 2 is a schematic diagram of a pole piece after disassembling a battery cell according to Comparative Example 1 of the present invention;

[0049] Figure 3 is a schematic diagram of a disassembled electrode sheet of a battery cell according to Embodiment 1 of the present invention;

[0050] Figure 4 is a schematic diagram of a disassembled electrode sheet of a battery cell according to Example 2 of the present invention;

[0051] Figure 5 is a schematic diagram of a disassembled electrode sheet of a battery cell according to Example 3 of the present invention;

[0052] Figure 6 It is a schematic diagram of the electrode sheet after the battery cell is disassembled according to Example 4 of the present invention. DETAILED DESCRIPTION

[0053] Some embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0054] The present invention provides a method for infiltrating an alkali metal ion battery cell with an electrolyte, referring to Figure 1 ,include:

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

[0056] S2: During the soaking process, constant voltage charging is performed at 0.2V-1V for the first preset time.

[0057] The battery cell described in step S1 includes a plurality of cathode plates and a plurality of anode plates, and a separator is provided between adjacent cathode plates and anode plates.

[0058] The cathode electrode sheet, the anode electrode sheet and the separator can be made into a battery cell through lamination or winding process.

[0059] In the traditional battery cell manufacturing process, after the injection step is completed, the battery cell usually needs to go through a long static stage. The main purpose of this stage is to allow the electrolyte to fully infiltrate the internal structure of the battery cell. However, this static process not only consumes a lot of time, but its infiltration effect is often not ideal. Since the electrolyte fails to fully infiltrate the interior of the battery cell, this will have an adverse effect on the overall performance of the battery, and thus affect the battery's service life and efficiency.

[0060] The present invention proposes a new technical solution for electrolyte infiltration of battery cells, aiming to improve the infiltration effect of the electrolyte to optimize the performance and efficiency of the battery. Specifically, after the single-cell injection is completed in the present invention, the battery cell is charged within a specific voltage range. In this way, the present invention adds a constant voltage charging step before the battery cell is formed. This process provides an electric field environment for the battery cell, thereby forming an electric capillary phenomenon on the battery's pole piece. These electric capillaries can significantly accelerate the wetting process of the internal electrodes of high-energy batteries, thereby improving the overall performance and service life of the battery. Through this method, the electrochemical reaction efficiency of the battery is improved, and the charge and discharge performance of the battery is also significantly improved.

[0061] The present invention enables the electrolyte to penetrate into the battery core faster, thereby significantly improving the effect of the electrolyte infiltrating the pole piece and improving the battery performance. This improvement not only improves production efficiency, but also may reduce production costs, ultimately bringing significant economic benefits to the battery core manufacturing industry.

[0062] Compared with the existing methods such as heat stabilization, adding wetting agent and changing electrode structure, the present invention has significant advantages in compatibility with the existing manufacturing process. Specifically:

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

[0064] 2. The present invention does not introduce any new electrolyte components, thereby avoiding changes to the electrolyte system. This is because new components may have a negative impact on the performance of the battery, thereby affecting the overall performance and reliability of the battery. Therefore, the present invention maintains the stability of the electrolyte system.

[0065] 3. The present invention does not change the electrode structure. This is because changes in the electrode structure require adaptive adjustments to other processes, such as the electrode slicing method, the electrode assembly process, etc. These changes involve changes in design processes, tooling, and equipment, which have a significant impact on conventional production lines.

[0066] The present invention only adds a specific charging procedure before the charging process of formation. This procedure is well compatible with the existing process and can optimize the wettability of the battery while improving the battery production efficiency. In this way, the present invention not only improves the infiltration of the electrolyte, thereby improving the overall performance and reliability of the battery, but also ensures production efficiency.

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

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

[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 generating electric capillaries, making it easier for the electrolyte to infiltrate 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, thereby improving the electrolyte infiltration effect.

[0070] The present invention constructs an electric field by setting a constant voltage charge, so that the electrolyte can spread and penetrate the surface of the pole piece more evenly. This process is of great significance for improving the performance and life of the battery.

[0071] In one embodiment, in step S2, during the constant voltage charging, the battery cell is vacuumed.

[0072] In a specific embodiment, when the battery cell is subjected to a vacuum treatment, the vacuum degree inside the battery cell is maintained in the range of -20 KPa to -50 KPa. In this way, the air pressure inside the battery cell can be effectively controlled.

[0073] The present invention adds a constant voltage charging step before the battery cell is subjected to the formation treatment. This process provides the battery with the necessary electric field, so that electric capillaries can be formed on the positive and negative pole pieces. The existence of these electric capillaries can significantly accelerate the wetting process of the electrodes inside the battery. The formation of the electric capillaries is due to the effect of the electric field, which causes the liquid molecules on the surface of the pole piece to rearrange under the action of the electric field force, thereby forming a special capillary structure. The existence of this structure can effectively promote the diffusion and wetting of the electrolyte on the electrode surface.

[0074] After the battery cell is filled, the gas inside the battery cell and in the pores of the positive and negative electrode sheets and the separator can be further discharged by vacuuming with negative pressure. This process is crucial for the infiltration of the electrolyte. When the gas is effectively discharged, the electrolyte can more easily fill these pores, thereby ensuring sufficient contact between the electrolyte and the electrode material. This sufficient contact is a prerequisite for the full performance of the battery.

[0075] The mutual cooperation and promotion of negative pressure vacuuming and electric capillary formed by electric field can greatly improve the infiltration efficiency of electrolyte.

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

[0077] In one embodiment, before the step of constant voltage charging at 0.2V-1V, the method further comprises:

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

[0079] The static temperature can be room temperature, no high temperature environment is required.

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

[0081] Charging the battery cell with moderate pre-wetting can promote and optimize the construction of the electric field and the formation of electric capillaries. Proper wetting can reduce the interfacial tension between the electrolyte and the electrode. This helps the electrolyte to penetrate more easily into the tiny pores of the electrode during the subsequent charging process, thereby increasing the penetration depth of the electrolyte. The properly wetted electrode surface provides favorable conditions for the formation of the electrocapillary phenomenon. Wetting allows the electrolyte to adhere more closely to the electrode surface and form a stable capillary structure under the action of the electric field.

[0082] The present invention also provides a method for infiltration formation of a battery cell, comprising:

[0083] The battery cell is wetted by the method;

[0084] The soaked battery cells are then formed.

[0085] First, the present invention proposes a special charging promotion method, which ensures that the battery cell can be fully infiltrated by forming electric capillaries. The full infiltration of this battery cell is the basis for the subsequent formation process, because only when the battery cell is completely immersed in the electrolyte can it ensure the best performance during the formation process. The full degree of infiltration has a great influence on the performance of the battery. For example, when the electrolyte wettability is poor, the ion transmission path becomes longer, which hinders the shuttle of lithium ions between the positive and negative electrodes, thereby affecting the charge transfer efficiency. Uneven infiltration will lead to uneven current density distribution, and the formed electrolyte interface film (SEI) is unstable, causing a series of safety issues.

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

[0087] After the battery cell is fully soaked, the next step is the formation process. Through the formation process, a series of charge and discharge cycles are carried out inside the battery cell to activate the active substances inside the battery so that it has normal charge and discharge capabilities. This process has a significant impact on the performance and life of the battery.

[0088] In one embodiment, the step of forming the soaked battery cell comprises:

[0089] The soaked battery cell is charged with a charging current of 0.1C-0.2C.

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

[0091] Each time charging, constant current charging is adopted.

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

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

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

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

[0096] First, the soaked battery cell is charged multiple times using a charging current of a first preset rate;

[0097] Then, the battery cells charged at the first preset rate are charged multiple times with a charging current at a second preset rate;

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

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

[0100] The soaked cells were charged at a constant current of 0.1C for 7 min.

[0101] Let stand for 5 minutes;

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

[0103] Let stand for 5 minutes;

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

[0105] Let stand for 5 minutes;

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

[0107] Let stand for 5 minutes;

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

[0109] Let stand for 5 minutes;

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

[0111] Let stand for 5 minutes;

[0112] Charge at 0.2C constant current 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 adopting the above-mentioned infiltration formation method.

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

[0116] The lithium-ion battery prepared by the infiltration formation method proposed in the present invention shows extremely high compatibility with existing production lines. This high compatibility means that the method can be easily integrated into the existing production process without large-scale transformation or replacement of existing equipment. Therefore, this method is not only conducive to the industrialization of lithium-ion batteries, but also greatly reduces the threshold and cost of promoting new technologies. Thereby accelerating the production efficiency and quality improvement of lithium-ion batteries, and further promoting technological progress and market expansion of the entire industry.

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

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

[0119] The following uses an infiltration formation method with different parameters to prepare lithium-ion battery cells. After the formation is completed, the cells are disassembled to observe the status of the electrodes.

[0120] Comparative Example 1

[0121] The 2Ah lithium-ion battery cell that has just been filled with liquid is placed at 25°C for 2 hours.

[0122] After the standing is completed, the formation is carried out, and the formation includes the following steps:

[0123] The soaked cells were charged at a constant current of 0.1C for 7 min.

[0124] Let stand for 5 minutes;

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

[0126] Let stand for 5 minutes;

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

[0128] Let stand for 5 minutes;

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

[0130] Let stand for 5 minutes;

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

[0132] Let stand for 5 minutes;

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

[0134] Let stand for 5 minutes;

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

[0136] Let stand for 5 minutes.

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

[0138] Disassemble the fully charged battery cell, refer to Figure 2 By observing the state of the electrode, it was found that after the formation, there were a large number of purple spots on the fully charged interface, dark lines in the middle, and lithium deposition, indicating that the electrolyte infiltration was insufficient, resulting in local difficulty in lithium embedding, causing lithium deposition and dark lines.

[0139] Comparative Example 2

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

[0141] After fully charged, the battery cell was disassembled and the electrode status was observed. It was found that after the formation, the fully charged interface was good, with no purple spots, some dark lines, and no lithium deposition. The presence of dark lines will lead to lithium deposition in the subsequent battery cycle, which poses a safety risk.

[0142] Comparative Example 3

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

[0144] The fully charged battery cell was disassembled and the electrode status was observed. It was found that the fully charged interface was good after formation, with no purple spots, dark lines, or lithium deposition.

[0145] Example 1

[0146] Charge the 2Ah lithium-ion battery cell that has just been filled with liquid at a constant voltage of 0.2V for 2h at 25℃, and set the lower limit current to 0A.

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

[0148] Disassemble the fully charged battery cell, refer to Figure 3 By observing the state of the negative electrode, it was found that the purple spots on the fully charged interface and the dark lines in the middle were reduced compared with those in comparative examples 1 and 2, and there was no lithium precipitation, indicating that the wetting was improved and the battery performance was improved.

[0149] Example 2

[0150] Charge the 2Ah lithium-ion battery cell that has just been filled with liquid at a constant voltage of 0.3V for 2h at 25℃, and set the lower limit current to 0A.

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

[0152] Disassemble the fully charged battery cell, refer to Figure 4 , and observed the state of the negative electrode sheet. It was found that after the formation, the purple spots on the full charge interface and the dark lines in the middle were reduced compared with those in Example 1, and there was no lithium precipitation, indicating that the infiltration was improved and the battery performance was improved.

[0153] Example 3

[0154] Charge the 2Ah lithium-ion battery cell that has just been filled with liquid at a constant voltage of 0.5V for 2h at 25℃, and set the lower limit current to 0A.

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

[0156] Disassemble the fully charged battery cell, refer to Figure 5 , and observed the state of the negative electrode sheet. It was found that after the formation, the purple spots on the full charge interface and the dark lines in the middle were reduced compared with those in Example 2, and there was no lithium precipitation, indicating that the infiltration was improved and the battery performance was improved.

[0157] Example 4

[0158] Charge the 2Ah lithium-ion battery cell that has just been filled with liquid at a constant voltage of 1V for 2h at 25℃, and set the lower limit current to 0A.

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

[0160] Disassemble the fully charged battery cell, refer to Figure 6 By observing the state of the negative electrode, it was found that: after the formation was completed, there were a small amount or trace purple spots on the full charge interface, the dark pattern in the middle disappeared, and there was no lithium precipitation, indicating that the infiltration was improved and the battery performance was improved.

[0161] Comparative Example 4

[0162] Charge the 2Ah lithium-ion battery cell that has just been filled with liquid at a constant voltage of 1.5V for 2h at 25℃, and set the lower limit current to 0A.

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

[0164] The fully charged battery cell was disassembled and the state of the negative electrode was observed. It was found that purple spots and lithium deposition were found on the fully charged interface. This was mainly because as the voltage increased, the constant current charging effect increased, and the electrolyte decomposed and produced gas, resulting in a worse constant voltage effect.

[0165] Example 5

[0166] Charge the 2Ah lithium-ion battery cell that has just been filled with liquid at a constant voltage of 0.7V for 3 hours at 25℃, and set the lower limit current to 1A.

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

[0168] The fully charged battery cell was disassembled and the state of the negative electrode was observed. It was found that there were a small amount of purple spots on the fully charged interface, no obvious dark lines and no lithium deposition.

[0169] Example 6

[0170] Charge the lithium-ion battery cell that has just been filled with liquid at a constant voltage of 0.8V for 1h at 25℃, and set the lower limit current to 0.5A.

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

[0172] The fully charged battery cell was disassembled and the electrode status was observed. It was found that there were a small amount of purple spots on the fully charged interface, no obvious dark lines and no lithium deposition.

[0173] Example 7

[0174] A 2Ah lithium-ion battery cell that has just been filled with liquid is charged at a constant voltage of 0.3V for 2 hours at 25°C, and the vacuum degree in the cell is maintained at -30KPa when the cell is evacuated. The lower limit current is set to 0A.

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

[0176] The fully charged battery cell was disassembled and the electrode status was observed. It was found that the purple spots on the fully charged interface and the dark lines in the middle were reduced compared with those in Example 2 after the formation, and there was no lithium precipitation, indicating that the infiltration was improved and the battery cell performance was improved.

[0177] Example 8

[0178] A 2Ah lithium-ion battery cell that has just been filled with liquid is charged at a constant voltage of 0.3V for 2 hours at 25°C, and the vacuum degree in the cell is maintained at -20KPa when the cell is evacuated. The lower limit current is set to 0A.

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

[0180] The fully charged battery cell was disassembled and the electrode status was observed. It was found that the purple spots on the fully charged interface and the dark lines in the middle were reduced compared with those in Example 2 after the formation, and there was no lithium precipitation, indicating that the infiltration was improved and the battery cell performance was improved.

[0181] Example 9

[0182] A 2Ah lithium-ion battery cell that has just been filled with liquid is charged at a constant voltage of 0.3V for 2 hours at 25°C, and the vacuum degree in the cell is maintained at -50KPa when the cell is evacuated. The lower limit current is set to 0A.

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

[0184] The fully charged battery cell was disassembled and the electrode status was observed. It was found that the purple spots on the fully charged interface and the dark lines in the middle were reduced compared with those in Example 2 after the formation, and there was no lithium precipitation, indicating that the infiltration was improved and the battery cell performance was improved.

[0185] Example 10

[0186] A 2Ah lithium-ion battery cell that has just been filled with liquid is charged at 1V constant voltage for 1.5 hours at 25°C, and the vacuum degree in the cell is maintained at -30KPa when the cell is evacuated. The lower limit current is set to 0A.

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

[0188] The fully charged battery cell was disassembled and the electrode status was observed. It was found that after the formation, the purple spots on the fully charged interface and the dark lines in the middle disappeared, and there was no lithium deposition, indicating that the infiltration was improved and the battery cell performance was improved.

[0189] Embodiment 11

[0190] The 2Ah lithium-ion battery cell that has just been filled with liquid was left to stand for 2 hours, and then charged at a constant voltage of 0.8V for 1.5 hours at 25°C. The lower current limit was set to 0A.

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

[0192] The fully charged battery cell was disassembled and the electrode status was observed. It was found that after the formation, the purple spots on the fully charged interface and the dark lines in the middle disappeared, and there was no lithium deposition, indicating that the infiltration was improved and the battery cell performance was improved.

[0193] The main parameters and the states of the formed electrodes of the above-mentioned embodiments 1-11 and comparative examples 1-4 are shown in Table 1.

[0194] Table 1 Main parameters of Examples 1-11 and Comparative Examples 1-4 and the state of the electrode after formation

[0195]

[0196]

[0197] In the technical solution of the present invention, before the battery formation process begins, constant voltage charging is set to promote electrolyte infiltration. In this way, an electric field is formed on the pole piece of the battery, thereby promoting the formation of electric capillaries. The presence of electric capillaries can significantly accelerate the internal wetting process of high energy density batteries. Through the application of this electric field-promoted infiltration technology, not only the waiting time of the battery during the static process is significantly reduced, but also the infiltration effect between the electrode and the electrolyte is greatly improved.

[0198] A short period of rest before constant voltage charging or appropriate vacuuming during constant voltage charging can promote the formation of the battery electrode electric field and significantly improve the state of the electrode after formation. The implementation of this technology has significantly improved the state of the electrode after formation and reduced defects, which helps improve the production efficiency of the battery, as well as the overall performance and life of the battery.

[0199] The process control of the present invention is simple, constant voltage charging at room temperature can promote electrolyte infiltration, and after the constant voltage charging for promoting infiltration is completed, formation can be started directly without standing, which greatly improves production efficiency.

[0200] It should be pointed out that although the various steps in the above embodiments are described in a specific order, those skilled in the art can understand that in order to achieve the effects of the present invention, different steps do not have to be performed in such an order. They can be performed simultaneously (in parallel) or in other orders. These changes are within the scope of protection of the present invention.

[0201] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle 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 these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A method for infiltrating an alkali metal ion battery cell with an electrolyte, characterized in that: include: Injecting electrolyte into the battery cell to wet the battery cell; During the infiltration process, constant voltage charging is performed at 0.2V-1V for a first preset time; wherein, the battery cell includes a plurality of cathode plates and a plurality of anode plates, and a diaphragm is provided between adjacent cathode plates and anode plates.

2. The method according to claim 1, characterized in that The first preset duration of constant voltage charging at 0.2-1V includes: At 0.2-1V, constant voltage charging for 1-3 hours.

3. The method according to claim 1, characterized in that: During the constant voltage charging, the battery core is evacuated.

4. The method according to claim 3, characterized in that: When the battery core is evacuated, the vacuum degree in the battery core is maintained at -20 KPa to -50 KPa.

5. The method according to claim 1, characterized in that When charging at constant voltage, set the lower current limit to 0-1A.

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

7. A method for infiltration formation of a battery cell, characterized in that: include: The battery cell is wetted by any method of claims 1 to 6; The soaked battery cells are then formed.

8. The method according to claim 7, characterized in that The forming of the soaked battery cell comprises: The soaked battery cell is charged with a charging current of 0.1C-0.2C.

9. The method according to claim 8, characterized in that The soaked battery cell is charged multiple times with a charging current of 0.1C-0.2C, and each charging time is 7-30 minutes.

10. The method according to claim 9, characterized in that A rest time is set after each charging, wherein the rest time is 4-8 minutes.

11. The method according to claim 9, characterized in that The number of charging times is 4-10 times.

12. The method according to any one of claims 7 to 11, characterized in that: The formation process comprises: Firstly, the soaked battery cell is charged multiple times with a charging current of a first preset rate; Then, a charging current of a second preset rate is used to perform multiple charging operations; Wherein, the second preset magnification is greater than the first preset magnification.

13. The method according to any one of claim 12, characterized in that: The formation process comprises: The soaked cells were charged at a constant current of 0.1C for 7 min. Let stand for 5 minutes; Charge at 0.1C constant current for 23 minutes; Let stand for 5 minutes; Charge at 0.1C constant current for 18 minutes; Let stand for 5 minutes; Charge at 0.1C constant current for 18 minutes; Let stand for 5 minutes; Charge at 0.1C constant current for 24 minutes; Let stand for 5 minutes; Charge at 0.2C constant current for 24 minutes; Let stand for 5 minutes; Charge at 0.2C constant current for 30 minutes; Let stand for 5 minutes.

14. An alkali metal ion battery cell, characterized in that: The method is obtained by the infiltration chemical method according to any one of claims 7 to 13.

15. The battery cell according to claim 14, characterized in that: The alkali metal ion battery cell is a lithium ion battery cell.

16. The battery cell according to claim 15, characterized in that: The active material of the anode electrode is lithium iron phosphate.

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