Liquid injection method, battery cell and electric equipment
By controlling the amount and pressure of electrolyte injection in batches, the problem of electrode wrinkling during the electrolyte injection process of secondary batteries was solved, improving the safety and lifespan of the cells, while also increasing the efficiency of electrolyte injection and reducing costs.
Patent Information
- Application Number
- CN202410597199.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-14
- Publication Date
- 2025-11-14
AI Technical Summary
Existing electrolyte injection methods for secondary batteries tend to create wrinkles on the electrode plates of the cells, leading to reduced cell safety and cycle life.
A batch injection method is adopted, with the single injection volume controlled to be less than or equal to 80g. First, a vacuum is drawn and then negative pressure is applied, and positive pressure is gradually increased. Combined with positive and negative pressure circulation, the electrolyte inflow rate is controlled to avoid electrode impact.
Reduce or avoid electrode wrinkling problems, improve cell safety and cycle life, shorten electrolyte injection time, and reduce manufacturing costs.
Smart Images
Figure CN120955322A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of secondary battery technology, and in particular to a liquid injection method, a battery cell, and an electrical device. Background Technology
[0002] In recent years, with the rapid development of the new energy battery industry, the market share of new energy vehicles has been increasing year by year. As the main power source for new energy vehicles, the demand for secondary batteries is growing daily, and people are also placing higher demands on their performance. In secondary batteries, the electrolyte is a crucial medium for ensuring ion transport, and the electrolyte injection process, as one of the key steps in secondary battery production, has a significant impact on the battery's performance.
[0003] Currently, the electrolyte injection method for secondary batteries is usually to inject the electrolyte into the cell in one go. Specifically, the cell is first evacuated, and the pressure difference between the inside and outside of the cell is used to drive the electrolyte to be injected into the cell in one go. Then, positive pressure is applied or negative pressure is applied to allow the cell to be left to stand and circulate, so that the electrolyte injected into the cell can fully wet the inner electrode plates and separator of the cell.
[0004] However, in the winding process of square aluminum-cased battery cells, the positive electrode, negative electrode, and separator are wound together in a spiral. The tension of the electrode and separator decreases gradually from the inner to the outer ring, resulting in relatively weak adhesion of the outer electrode. During electrolyte injection, the outer electrode is easily impacted by the electrolyte, forming wrinkles. During subsequent charging and discharging, lithium plating and black spots are prone to occur at the wrinkled areas of the electrode, leading to safety hazards and reducing the cycle life of the battery. Summary of the Invention
[0005] The technical problem to be solved by the present invention is to provide a liquid injection method, a battery cell and an electrical device to solve the problem that the liquid injection method of existing secondary batteries is prone to forming wrinkles on the electrode sheets of the battery cell, which leads to a reduction in battery cell safety and cycle life.
[0006] To solve the above problems, the present invention is achieved through the following technical solution:
[0007] This invention proposes a liquid injection method, the method comprising:
[0008] Determine the total injection volume and single injection volume corresponding to the battery cell to be injected; the single injection volume is less than or equal to 80g, and the total injection volume is greater than the single injection volume;
[0009] Based on the total injection volume and the single injection volume, determine the total number of injections and the sub-injection volume for each injection.
[0010] The cavity of the cell to be injected with liquid is evacuated to a first negative pressure and maintained for 50 to 60 seconds.
[0011] According to the sub-injection volume, the first injection is performed into the cell to be injected with liquid under the first negative pressure in the cavity, to obtain the cell to be injected with liquid after one injection; the injection time of the first injection is the first time.
[0012] A first positive pressure is applied to the cavity of the cell to be injected after the first injection, and the cell to be injected after the first injection is injected for the nth time according to the sub-injection volume, to obtain a cell to be injected after n injections; n is an integer greater than 1 and less than or equal to the total number of injections, the injection time of the nth injection is the nth time, and the nth time is greater than or equal to the first time;
[0013] When n equals the total number of injection cycles, the cells to be injected with liquid are subjected to positive and negative pressure cycling after the n injection cycles to obtain the injected cells.
[0014] Furthermore, the nth duration is t+10(n-1)s; where t is the first duration.
[0015] Furthermore, the first duration is 10s to 20s.
[0016] Furthermore, the first negative pressure is -95 kPa to -85 kPa; the first positive pressure is 95 kPa to 105 kPa.
[0017] Further, determining the total number of injections and the sub-injection volume for each injection based on the total injection volume and the single injection volume includes:
[0018] When the total injection volume is divisible by the single injection volume, the quotient of the total injection volume and the single injection volume is determined as the total number of injections, and the sub-injection volume of each injection is the single injection volume.
[0019] If the total injection volume cannot be divided evenly by the single injection volume, add 1 to the integer part of the quotient of the total injection volume and the single injection volume to obtain the total number of injections. The sub-injection volume of each injection before the last injection is the single injection volume, and the sub-injection volume of the last injection is less than the single injection volume.
[0020] Furthermore, the single injection volume is 60g to 80g.
[0021] Further, the step of performing positive and negative pressure cycling on the cell to be injected after n injections, when n equals the total number of injections, to obtain the injected cell, includes:
[0022] The cell to be injected with electrolyte after n injections is subjected to m positive and negative pressure cycles to obtain a cell to be injected with electrolyte after m positive and negative pressure cycles; m is any integer from 3 to 5;
[0023] A second positive pressure is applied to the cavity of the cell to be injected with liquid after m cycles of positive and negative pressure treatment, and the second positive pressure is maintained for a third duration.
[0024] After maintaining the second positive pressure for a third time, the pressure of the cavity of the cell to be injected with liquid is restored from the second positive pressure to the normal pressure after the m positive and negative pressure cycles, thus obtaining the liquid-injected cell;
[0025] The second positive pressure is 95 kPa to 105 kPa, and the third duration is 5 s to 6 s.
[0026] Further, the step of performing m positive and negative pressure cycles on the cell to be injected with electrolyte after n injections to obtain the cell to be injected with electrolyte after m positive and negative pressure cycles includes:
[0027] When n equals the total number of injections, the cavity of the cell to be injected after n injections is evacuated to a second negative pressure and maintained under the second negative pressure for a fourth time.
[0028] After maintaining the second negative pressure for a fourth time, a third positive pressure is applied to the cavity of the cell to be injected with liquid after the nth injection, and the third positive pressure is maintained for a fifth time to obtain the cell to be injected with liquid after one positive and negative pressure cycle treatment.
[0029] The second negative pressure is -50 kPa to -40 kPa, and the third positive pressure is 190 kPa to 210 kPa; the fourth duration is 5 to 6 seconds, and the fifth duration is 50 to 60 seconds.
[0030] The present invention also proposes a battery cell comprising an electrolyte, wherein the electrolyte is injected into the battery cell by the injection method described in any of the preceding claims.
[0031] The present invention also proposes an electrical device, the electrical device comprising the battery cell as described above, the battery cell serving as the power supply for the electrical device.
[0032] Compared with the prior art, the embodiments of the present invention have the following advantages:
[0033] The electrolyte injection method provided in this invention reduces the impact force of the electrolyte on the electrode during injection by setting the single injection volume to less than or equal to 80g, thereby reducing or avoiding electrode wrinkling. Before the first injection, the cavity of the cell to be injected is evacuated to a first negative pressure and maintained for 50 to 60 seconds. This facilitates the expulsion of air from the cell cavity and prevents air from hindering the injection process. During the first injection, the electrolyte's own weight and the first negative pressure of the cell cavity promote the flow of electrolyte into the cell. Inside the cavity of the core, during the nth electrolyte injection process, a first positive pressure is applied to the cavity of the core to be injected. The first positive pressure ensures that the electrolyte flows smoothly into the cavity of the core to be injected. At the same time, by controlling the pressure value of the first positive pressure, the flow rate of the electrolyte into the cavity of the core to be injected can be controlled, avoiding the impact on the electrode plates in the core due to the excessive flow rate of the electrolyte. This further reduces the probability of electrode plate wrinkling and avoids lithium plating and black spots at the electrode plate wrinkles during subsequent charging and discharging of the core, thereby improving the safety of the core and extending its cycle life.
[0034] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit the invention. Attached Figure Description
[0035] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0036] Figure 1 This is a flowchart of the steps of an injection method according to the present invention;
[0037] Figure 2 This is a schematic diagram of the structure of a liquid injection system according to the present invention;
[0038] Figure 3 This is an image showing the appearance of an electrode sheet according to the present invention;
[0039] Figure 4 This is another electrode appearance diagram of the present invention. Detailed Implementation
[0040] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0041] The following description, in conjunction with the accompanying drawings, details a liquid injection method, battery cell, and electrical device provided in this application through specific embodiments and application scenarios.
[0042] Reference Figure 1 The diagram illustrates a step-by-step flowchart of an injection method according to an embodiment of the present invention, which includes steps S101 to S105:
[0043] Step S101: Determine the total amount of electrolyte to be injected and the amount of electrolyte injected at one time for the battery cell to be injected.
[0044] Wherein, the single injection volume is less than or equal to 80g, and the total injection volume is greater than the single injection volume.
[0045] In this embodiment of the invention, the battery cell to be injected with electrolyte can be any battery cell that requires electrolyte injection. The battery cell to be injected with electrolyte can be a square aluminum shell battery cell, which includes a shell, a core, and a top cover. The battery cell obtained in step S106 includes a shell, a core, electrolyte, and a top cover; wherein, the core includes a positive electrode plate, a negative electrode plate, and a separator.
[0046] Specifically, in step S101, the total amount of liquid injected into the cell can be determined according to the battery capacity of the cell to be injected. For example, when the battery capacity of the cell to be injected is 100Ah, the total amount of liquid injected is 240g; when the battery capacity of the cell to be injected is 136Ah, the total amount of liquid injected is 380g; and when the battery capacity of the cell to be injected is 280Ah, the total amount of liquid injected is 890g.
[0047] The amount of electrolyte injected at one time can be determined based on the impact force of the electrolyte on the electrode during the process. The amount of electrolyte injected at one time can be less than or equal to the maximum mass or volume of electrolyte that can be injected at one time without wrinkling the electrode.
[0048] In this embodiment of the invention, the total electrolyte injection volume for the cell to be injected is greater than the single electrolyte injection volume for the cell to be injected, and the single electrolyte injection volume can be any volume greater than 0g and less than or equal to 80g. It is understood that when the single electrolyte injection volume is greater than 80g, the impact force of the electrolyte on the electrode sheets in the core is too great during the injection process, and the outer electrode sheets of the cell are easily wrinkled due to the impact of the electrolyte. When the single electrolyte injection volume is too small, although wrinkling of the electrode sheets due to the impact of the electrolyte can be avoided, the injection efficiency is low, affecting the cell's production efficiency. In practical applications, the single electrolyte injection volume can be determined by balancing the cell's production efficiency while avoiding wrinkling of the electrode sheets during the injection process.
[0049] Step S102: Determine the total number of injections and the sub-injection volume for each injection based on the total injection volume and the single injection volume.
[0050] In this embodiment of the invention, when the total injection volume and the single injection volume are determined in step S101, the total number of injections corresponding to the cell to be injected, and the sub-injection volume for each injection, can be determined based on the total injection volume and the single injection volume. It is understood that when the total injection volume is greater than the single injection volume, the total number of injections determined in step S102 is at least 2.
[0051] As an optional implementation, the total number of injections and the sub-injection volume for each injection are determined based on the total injection volume and the single injection volume. Specifically: First, the sub-injection volume for the first injection is determined to be any value greater than 0g and less than the single injection volume; then, the sub-injection volume for the last injection is determined as the single injection volume; next, according to a preset injection volume increment rule, the sub-injection volumes corresponding to each injection number between the first and last injections are determined, and the total number of injections is determined; wherein, the sub-injection volume for the first injection and the preset injection volume increment rule meet the requirements of cell production efficiency. For example, if the sub-injection volume for the first injection is 50g, the sub-injection volume for the last injection is 70g, and the preset injection volume increment rule is that the sub-injection volume increases by 5g each time, then the sub-injection volume for the second injection is 55g, the sub-injection volume for the third injection is 60g, the sub-injection volume for the fourth injection is 65g, and the total number of injections is 5.
[0052] As another optional implementation, the total number of injections and the sub-injection volume for each injection are determined based on the total injection volume and the single injection volume. Specifically: First, the sub-injection volume of the first injection is determined as the single injection volume; then, the sub-injection volume of the last injection is determined as any value greater than 0g and less than the single injection volume; then, according to a preset injection volume decreasing rule, the sub-injection volumes corresponding to each injection number between the first and last injections are determined, and the total number of injections is determined; wherein, the sub-injection volume of the last injection and the preset injection volume decreasing rule meet the requirements of cell production efficiency. For example, if the sub-injection volume of the first injection is 70g, the sub-injection volume of the last injection is 40g, and the preset injection volume increasing rule is that the sub-injection volume decreases by 10g each time, then the sub-injection volume of the second injection is 60g, the sub-injection volume of the third injection is 50g, and the total number of injections is 4.
[0053] Step S103: Evacuate the cavity of the cell to be injected with liquid to a first negative pressure and maintain it for 50s to 60s.
[0054] In this embodiment of the invention, before the first liquid injection, the cavity of the cell to be injected is evacuated to a first negative pressure and maintained for 50s to 60s. For example, it can be one or any two of the values of 50s, 52s, 54s, 56s, 58s and 60s. In this way, the air in the cavity of the cell to be injected can be fully discharged, avoiding the air in the cavity from causing resistance to the liquid injection process.
[0055] The cavity of the battery cell to be injected with electrolyte is the cavity formed between the positive electrode, negative electrode, and separator in the core. The first negative pressure can be determined based on the air removal effect in the cavity of the battery cell to be injected with electrolyte; however, this embodiment of the invention does not specifically limit this.
[0056] Step S104: According to the sub-injection volume, perform the first injection into the cell to be injected with liquid under the first negative pressure in the cavity, and obtain the cell to be injected with liquid after one injection.
[0057] The duration of the first injection is called the first duration, which is the total duration from the first moment when the first injection begins to the second moment when the first injection ends.
[0058] In this step, the sub-injection volume is specifically the sub-injection volume of the first injection. Specifically, the electrolyte corresponding to the sub-injection volume of the first injection is injected into the cavity of the cell to be injected according to the first time. During the injection process, the flow rate of the electrolyte into the cavity of the cell to be injected is uniform, that is, the ratio of the sub-injection volume of the first injection to the first time is maintained within the preset flow rate range.
[0059] It is understandable that the amount of electrolyte in the cell to be injected after one injection is the sub-injection amount of the first injection.
[0060] In this embodiment of the invention, the injection time of the first injection is controlled as a first time, which can control the flow rate of the electrolyte into the cavity of the cell to be injected. During the first time, the electrode and diaphragm in the cell can also fully absorb the electrolyte flowing into the cavity of the cell to be injected.
[0061] Reference Figure 2 The diagram shows a schematic of a liquid injection system according to an embodiment of the present invention. The liquid injection system includes a battery cell 10 to be injected and a liquid injection cup 20. The battery cell 10 to be injected includes a negative electrode 101, a positive electrode 102 and a first liquid injection port 103. The liquid injection cup 20 includes a pressure valve 201, a second liquid injection port 202 and a sealing rod 203. The battery cell 10 to be injected and the liquid injection cup 20 are connected through the first liquid injection port 103.
[0062] The negative electrode 101 of the battery cell 10 to be injected with electrolyte is connected to the negative electrode sheet in the core, and the positive electrode 102 of the battery cell 10 to be injected with electrolyte is connected to the positive electrode sheet in the core. When the second injection port 202 in the injection cup 20 is open, electrolyte can be injected into the injection cup 20 through the second injection port 202; when the sealing rod 203 in the injection cup 20 is down, the electrolyte in the injection cup 20 cannot flow into the battery cell 10; when the sealing rod 203 in the injection cup 20 is up, the electrolyte in the injection cup 20 can flow into the battery cell 10; the pressure valve 201 in the injection cup 20 is used to adjust the pressure in the cavity of the battery cell 10 to be injected with electrolyte when the sealing rod 203 is up.
[0063] Specifically, in step S103, the sealing rod 203 in the injection cup 20 can be lifted first, and then the cavity of the battery cell 10 to be injected can be evacuated to the first negative pressure through the air pressure valve 201 and maintained for 50s to 60s.
[0064] In step S104, the sealing rod 203 in the injection cup 20 can be lowered first, and then the electrolyte corresponding to the first injection volume can be injected into the injection cup 20 through the second injection port 202. Then, the sealing rod 203 in the injection cup 20 can be raised, and the electrolyte can be injected into the cell 10 to be injected under the first negative pressure in the cavity through the first injection port 103. When all the electrolyte in the injection cup 20 has flowed into the cell 10 to be injected, the sealing rod 203 in the injection cup 20 can be lowered to obtain the cell 10 to be injected after one injection. The time from the lifting of the sealing rod 203 to the lowering of the sealing rod 203 is the first time.
[0065] Step S105: Apply a first positive pressure to the cavity of the cell to be injected with liquid after the first injection, and perform the nth injection on the cell to be injected with liquid after the first injection according to the sub-injection volume, to obtain the cell to be injected with liquid after n injections.
[0066] Wherein, n is an integer greater than 1 and less than or equal to the total number of injections, the injection duration of the nth injection is the nth duration, and the nth duration is greater than or equal to the first duration.
[0067] It is understandable that the nth electrolyte injection is any injection performed after the first electrolyte injection. During any electrolyte injection after the first injection, the pressure in the cavity of the cell to be injected is a first positive pressure. The first positive pressure ensures that the electrolyte flows smoothly into the cavity of the cell to be injected. In addition, by controlling the pressure value of the first positive pressure, the flow rate of the electrolyte into the cavity of the cell to be injected is also controlled, so as to avoid the impact on the electrode in the cell due to the excessive flow rate of the electrolyte, and reduce the probability of the electrode forming wrinkles.
[0068] In this embodiment of the invention, the nth duration of the nth injection can be the same as or greater than the first duration of the first injection; this embodiment of the invention does not impose a specific limitation on this. The nth duration is the total duration from the third moment after the start of the nth injection to the fourth moment after the end of the nth injection.
[0069] In this step, the sub-injection volume is specifically the sub-injection volume of the nth injection. For example, when n equals the total number of injections, the sub-injection volume in step S105 is the sub-injection volume of the last injection; when n equals 2, the sub-injection volume in step S105 is the sub-injection volume of the second injection.
[0070] Specifically, the electrolyte corresponding to the sub-injection volume of the nth injection can be injected into the cavity of the cell to be injected according to the nth time period. During the injection process, the flow rate of the electrolyte into the cavity of the cell to be injected is uniform, that is, the ratio of the sub-injection volume of the nth injection to the nth time period is maintained within the preset flow rate range.
[0071] It is understandable that the amount of electrolyte in the cell to be injected after n injections is equal to the sum of the sub-injection amounts from the first injection to the nth injection.
[0072] As an example, the total number of electrolyte injections is 3. After obtaining the electrolyte cell after one injection in step S104, firstly, a first positive pressure is applied to the cavity of the electrolyte cell after one injection, and the electrolyte cell after one injection is injected a second time according to the sub-injection amount of the second injection, to obtain the electrolyte cell after two injections; then, a first positive pressure is applied to the cavity of the electrolyte cell after two injections, and the electrolyte cell after two injections is injected a third time according to the sub-injection amount of the third injection, to obtain the electrolyte cell after three injections; wherein, the amount of electrolyte in the electrolyte cell after three injections is equal to the sum of the sub-injection amounts of the first injection, the second injection, and the third injection.
[0073] In this embodiment of the invention, by controlling the injection time of the nth injection to be the nth duration, the flow rate of the electrolyte into the cavity of the cell to be injected can be controlled. Furthermore, within the nth duration, the electrode and diaphragm in the cell can fully absorb the electrolyte flowing into the cavity of the cell to be injected.
[0074] Reference Figure 2 In step S105, firstly, electrolyte corresponding to the sub-injection volume of the nth injection is injected into the injection cup 20 through the second injection port 202; then, the sealing rod 203 in the injection cup 20 is lifted, and a first positive pressure is applied to the cavity of the battery cell 10 to be injected after the first injection through the air pressure valve 201. Under the action of the first pressure and the gravity of the electrolyte itself, the battery cell 10 to be injected is injected for the nth time through the first injection port 103. When all the electrolyte in the injection cup 20 has flowed into the battery cell 10 to be injected, the sealing rod 203 in the injection cup 20 is lowered to obtain the battery cell 10 to be injected after n injections. The time from lifting the sealing rod 203 to lowering the sealing rod 203 is the nth time.
[0075] Step S106: When n equals the total number of injections, perform positive and negative pressure cycling on the cell to be injected after n injections to obtain the injected cell.
[0076] Understandably, when n equals the total number of injections, it indicates that the nth injection is the last injection. At this time, the cell to be injected after n injections can be subjected to positive and negative pressure cycling to improve the wetting effect of the electrolyte on the electrode. After the cell to be injected after n injections is subjected to positive and negative pressure cycling, the injected cell can be obtained.
[0077] It should be noted that in the winding process of a square aluminum-cased battery cell, the positive electrode, negative electrode, and separator are wound together in a spiral shape. The tension of the electrode and separator gradually decreases from the inner to the outer ring, resulting in relatively weak adhesion of the outer ring electrode. Therefore, during electrolyte injection, the outer ring electrode is more susceptible to impact from the electrolyte, forming wrinkles. Based on the laws of conservation of momentum and mass, the following formula for the electrolyte impact force can be obtained:
[0078] F=ρ×Q×V out (1)
[0079] Where F represents the impact force of the electrolyte on the electrode, ρ represents the density of the electrolyte, Q represents the single injection volume of the electrolyte, and V out This indicates the flow rate of the electrolyte.
[0080] As can be seen from formula (1), under the condition that the electrolyte density remains unchanged, reducing the impact force of the electrolyte on the electrode requires reducing the single injection volume of the electrolyte and reducing the flow rate of the electrolyte. The flow rate of the electrolyte can be reduced by reducing the first negative pressure and the first positive pressure.
[0081] Currently, for high-capacity battery cells, the electrolyte is typically injected into the cell in a single injection. This large volume of electrolyte results in significant liquid impact on the outer electrode plates, easily causing unevenness and wrinkles. During subsequent charging and discharging, these wrinkled areas are prone to lithium plating and black spots, negatively impacting the cell's safety and cycle life. Furthermore, to prevent overflow after injection, the single-injection method requires increasing the number of positive and negative pressure cycles, thus extending the injection time and increasing manufacturing costs.
[0082] The electrolyte injection method provided in this invention reduces the impact force of the electrolyte on the electrode during injection by setting the single injection volume to less than or equal to 80g, thereby reducing or avoiding electrode wrinkling. Before the first injection, the cavity of the cell to be injected is evacuated to a first negative pressure and maintained for 50 to 60 seconds. This facilitates the expulsion of air from the cell cavity and prevents air from hindering the injection process. During the first injection, the electrolyte's own weight and the first negative pressure of the cell cavity promote the flow of electrolyte into the cell. Inside the cell cavity, during the nth electrolyte injection process, a first positive pressure is applied to the cavity of the cell to be injected. This first positive pressure ensures the smooth flow of electrolyte into the cell cavity while simultaneously controlling the flow rate of the electrolyte. This prevents excessively fast electrolyte flow from impacting the electrodes, further reducing the probability of electrode wrinkling and avoiding lithium plating and black spots at the wrinkled areas during subsequent charging and discharging. This improves cell safety and extends cycle life. Furthermore, injecting the electrolyte in batches helps improve electrode wetting efficiency, reduces the number of positive and negative pressure cycles, shortens injection time, increases injection efficiency, and lowers manufacturing costs.
[0083] Optionally, in some embodiments, the nth duration can be determined according to the following formula:
[0084] T n =t+10(n-1) (2)
[0085] Among them, T n t represents the nth time interval, t represents the first time interval, and n represents the number of injections.
[0086] For example, the first duration is 10s; when n is 2, the second duration of the second injection is 20s; when n is 6, the sixth duration of the sixth injection is 60s.
[0087] It is understandable that as the number of injection cycles increases, the amount of electrolyte in the cell to be injected continuously increases, the volume of the cavity in the cell to be injected gradually decreases, and the injection resistance gradually increases. In this embodiment of the invention, as the number of injection cycles increases, the injection time corresponding to each injection cycle after the first injection is extended according to the nth time being t+10(n-1)s. This can improve the wetting effect of the electrode sheet throughout the injection process, thereby shortening the time of positive and negative pressure cycle processing in step S106, improving the injection efficiency of the cell, and reducing the manufacturing cost of the cell.
[0088] Optionally, in some embodiments, the first duration is 10s to 20s; exemplaryly, the first duration can be a range of one or any two of 10s, 12s, 14s, 16s, 18s and 20s.
[0089] Optionally, in some embodiments, the first negative pressure is between -95 kPa and -85 kPa; exemplaryly, the first negative pressure can be a range of one or any two of -95 kPa, -93 kPa, -91 kPa, -89 kPa, -87 kPa and -85 kPa.
[0090] In this embodiment of the invention, the first negative pressure is controlled between -95 kPa and -85 kPa. This not only improves the air discharge efficiency in the cell cavity to be injected, but also avoids excessive negative pressure in the cell cavity from causing excessive impact force of the electrolyte on the electrode during the first injection process in step S104, thereby reducing the probability of electrode wrinkling.
[0091] Optionally, in some embodiments, the first positive pressure is 95 kPa to 105 kPa; exemplaryly, the first positive pressure can be a range of one or any two of 95 kPa, 97 kPa, 99 kPa, 101 kPa, 103 kPa and 105 kPa.
[0092] Understandably, if the initial positive pressure is too low, for example, less than the electrolyte injection resistance, electrolyte overflow is likely to occur at the injection port of the battery cell to be injected. If the initial positive pressure is too high, the flow rate of the electrolyte into the battery cell to be injected is too high, increasing the impact force of the electrolyte on the electrode and increasing the probability of electrode wrinkling. In this embodiment of the invention, the initial positive pressure is controlled between 95 kPa and 105 kPa, which avoids electrode wrinkling during the injection process and also prevents overflow, thus improving the feasibility of the injection method.
[0093] Optionally, in some embodiments, step S102, which determines the total number of injections and the sub-injection volume for each injection based on the total injection volume and the single injection volume, includes steps S1021 to S1022:
[0094] Step S1021: When the total injection volume is divisible by the single injection volume, the quotient of the total injection volume and the single injection volume is determined as the total number of injections, and the sub-injection volume of each injection is the single injection volume.
[0095] Step S1022: If the total injection volume cannot be divided evenly by the single injection volume, add 1 to the integer part of the quotient of the total injection volume and the single injection volume to obtain the total number of injections. The sub-injection volume of each injection before the last injection is the single injection volume, and the sub-injection volume of the last injection is less than the single injection volume.
[0096] In this embodiment of the invention, in the process of determining the total number of injections and the sub-injection volume of each injection based on the total injection volume and the single injection volume, the total number of injections can be determined by the quotient of the total injection volume divided by the single injection volume.
[0097] Specifically, when the total injection volume is divisible by the single injection volume, the quotient obtained by dividing the total injection volume by the single injection volume can be determined as the total number of injections. In this case, the sub-injection volume of each injection is the same and is a single injection volume.
[0098] If the total injection volume cannot be divided evenly by the single injection volume, the integer part of the quotient obtained by dividing the total injection volume by the single injection volume can be added to 1 to determine the total number of injections. In this case, in the total number of injections, the sub-injection volume of each injection before the last injection is the single injection volume, while the sub-injection volume of the last injection is less than the single injection volume.
[0099] The injection method provided in this invention is simple and easy to implement. It determines the total number of injections and the sub-injection volume of each injection based on the total injection volume and the single injection volume. While reducing or avoiding the occurrence of electrode wrinkling problems, it also simplifies the determination of the total number of injections and the sub-injection volume of each injection in the injection method, and improves the feasibility of the injection method.
[0100] Optionally, in some embodiments, the single injection volume is 60g to 80g; exemplaryly, the single injection volume can be a range of one or any two of 60g, 62g, 64g, 66g, 68g, 70g, 72g, 74g, 78g and 80g.
[0101] In this embodiment of the invention, to avoid wrinkles in the electrode sheets during the electrolyte injection process, and considering the production efficiency of the battery cell, the single electrolyte injection volume can be determined to be 60g to 80g. Specifically, if the single electrolyte injection volume is greater than 80g, the impact force of the electrolyte on the electrode sheets in the core is too great during the injection process, making the outer electrode sheets of the battery cell highly susceptible to wrinkles caused by the electrolyte impact. If the single electrolyte injection volume is less than 60g, it significantly impacts the production efficiency of the battery cell. Therefore, without affecting production efficiency, determining the single electrolyte injection volume to be 60g to 80g can reduce or avoid the occurrence of electrode sheet wrinkling.
[0102] Optionally, in some embodiments, step S106, where n equals the total number of injections, involves performing positive and negative pressure cycling on the cell to be injected after n injections to obtain an injected cell, including steps S1061 to S1063:
[0103] Step S1061: Perform m positive and negative pressure cycles on the cell to be injected after n injections to obtain the cell to be injected after m positive and negative pressure cycles.
[0104] Where m is any integer from 3 to 5, for example, m can be any of 3, 4, or 5.
[0105] Specifically, in the m positive and negative pressure cycle processes, the process of each positive and negative pressure cycle is the same or similar.
[0106] For example, when m is 3, firstly, the cell to be injected with liquid after n injections is subjected to one positive and negative pressure cycle treatment to obtain the cell to be injected with liquid after one positive and negative pressure cycle treatment; then, the cell to be injected with liquid after one positive and negative pressure cycle treatment is subjected to a second positive and negative pressure cycle treatment to obtain the cell to be injected with liquid after two positive and negative pressure cycle treatments; finally, the cell to be injected with liquid after two positive and negative pressure cycle treatments is subjected to a third positive and negative pressure cycle treatment to obtain the cell to be injected with liquid after three positive and negative pressure cycle treatments; wherein, the cell to be injected with liquid after three positive and negative pressure cycle treatments is the processing object of step S1062.
[0107] Step S1062: Apply a second positive pressure to the cavity of the cell to be injected with liquid after m cycles of positive and negative pressure treatment, and maintain the second positive pressure for a third duration.
[0108] In this step, after performing m positive and negative pressure cycles on the cell to be injected with electrolyte after n injections, a second positive pressure is applied to the cavity of the cell to be injected with electrolyte after m positive and negative pressure cycles, and the second positive pressure is maintained for a third duration. This can prevent overflow from the injection port of the cell to be injected with electrolyte after m positive and negative pressure cycles, thereby preventing the loss of electrolyte injected into the cell.
[0109] The second positive pressure is 95 kPa to 105 kPa. For example, the second positive pressure can be a value within the range of one or any two of 95 kPa, 97 kPa, 99 kPa, 101 kPa, 103 kPa, and 105 kPa. The third duration is 5 s to 6 s. For example, the third duration can be a value within the range of one or any two of 5 s, 5.1 s, 5.2 s, 5.3 s, 5.4 s, 5.5 s, 5.6 s, 5.7 s, 5.8 s, 5.9 s, and 6 s.
[0110] Step S1063: After maintaining the second positive pressure for a third time, the pressure of the cavity of the cell to be injected with liquid is restored from the second positive pressure to the normal pressure after the m positive and negative pressure cycles, thus obtaining the injected cell.
[0111] In this embodiment of the invention, after maintaining the second positive pressure for a third time, the pressure of the cavity of the cell to be injected with liquid after m positive and negative pressure cycles is restored from the second positive pressure to the normal pressure, which is beneficial to the separation of the cell to be injected with liquid from the injection cup after m positive and negative pressure cycles, thus obtaining the injected cell.
[0112] The electrolyte injection method provided in this embodiment of the invention requires only 3 to 5 cycles of positive and negative pressure treatment to achieve the desired wetting effect of the electrolyte on the electrode, thus shortening the time of positive and negative pressure cycle treatment, improving the electrolyte injection efficiency of the battery cell, and reducing the manufacturing cost of the battery cell.
[0113] Optionally, in some embodiments, step S1061, which involves performing m positive and negative pressure cycles on the cell to be injected after n injections, to obtain the cell to be injected after m positive and negative pressure cycles, includes steps A11 to A12:
[0114] Step A11: When n equals the total number of liquid injections, the cavity of the cell to be injected with liquid after n injections is evacuated to a second negative pressure and maintained under the second negative pressure for a fourth time.
[0115] Step A12: After maintaining the second negative pressure for a fourth time, apply a third positive pressure to the cavity of the cell to be injected with liquid after n injections, and maintain the third positive pressure for a fifth time to obtain the cell to be injected with liquid after one positive and negative pressure cycle.
[0116] This invention provides a specific implementation process for one positive and negative pressure cycle process in the process of obtaining a battery cell after m positive and negative pressure cycle processing after n injections; in the process of m positive and negative pressure cycle processing, each positive and negative pressure cycle processing is the same as or similar to the one positive and negative pressure cycle processing described in steps A11 to A12.
[0117] For example, when m is 3, firstly, through steps A11 to A12, the cell to be injected with liquid after n injections is subjected to a positive and negative pressure cycle treatment once to obtain the cell to be injected with liquid after one positive and negative pressure cycle treatment; then, according to the same or similar positive and negative pressure cycle treatment as steps A11 to A12, the cell to be injected with liquid after one positive and negative pressure cycle treatment is subjected to a second positive and negative pressure cycle treatment to obtain the cell to be injected with liquid after two positive and negative pressure cycle treatments; finally, according to the same or similar positive and negative pressure cycle treatment as steps A11 to A12, the cell to be injected with liquid after two positive and negative pressure cycle treatments is subjected to a third positive and negative pressure cycle treatment to obtain the cell to be injected with liquid after three positive and negative pressure cycle treatments.
[0118] The second negative pressure is between -50 kPa and -40 kPa. For example, the second negative pressure can be one or any two of the following: -50 kPa, -48 kPa, -46 kPa, -44 kPa, -42 kPa, and -40 kPa. The fourth duration is between 5 s and 6 s. For example, the fourth duration can be one or any two of the following: 5 s, 5.1 s, 5.2 s, 5.3 s, 5.4 s, 5.5 s, 5.6 s, 5.7 s, 5.8 s, 5.9 s, and 6 s.
[0119] The third positive pressure is from 190 kPa to 210 kPa, for example, the third positive pressure can be one or any two of the following values: 190 kPa, 192 kPa, 194 kPa, 196 kPa, 198 kPa, 200 kPa, 202 kPa, 204 kPa, 206 kPa, 208 kPa and 210 kPa; the fifth duration is from 50 s to 60 s, for example, the fifth duration can be one or any two of the following values: 50 s, 52 s, 54 s, 56 s, 58 s and 60 s.
[0120] The present invention also provides a battery cell comprising an electrolyte, wherein the electrolyte is injected into the battery cell by the injection method described in any of the preceding claims.
[0121] In practical applications, the liquid-filled battery cell provided in the embodiments of the present invention is subjected to formation, aging, and capacity testing to obtain the aforementioned battery cell.
[0122] For the above-described battery cell embodiments, the electrolyte contained therein is injected into the battery cell by the injection method described in any of the above embodiments, and the same technical effect can be achieved. To avoid repetition, it will not be described again here. For relevant details, please refer to the description of the injection method embodiments.
[0123] The present invention also provides an electrical device, the electrical device comprising the battery cell as described above, the battery cell serving as the power supply for the electrical device.
[0124] For the above-described electrical equipment embodiments, which include the battery cells as described above and achieve the same technical effects, they will not be repeated here to avoid repetition. For relevant details, please refer to the description of the liquid injection method embodiments.
[0125] To make the inventive objectives, technical solutions, and beneficial effects of this invention clearer, the invention is further described below with reference to embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.
[0126] The present invention will be described in detail below through embodiments.
[0127] Example 1
[0128] (1) Determine the total amount of liquid injected and the amount of liquid injected at a time for the cell to be injected; wherein, the battery capacity of the cell to be injected is 100Ah, the total amount of liquid injected is 240g, and the amount of liquid injected at a time is 80g.
[0129] (2) Determine the total number of injections and the sub-injection volume for each injection based on the total injection volume and the single injection volume; wherein, the total injection volume can be divided by the single injection volume, and the quotient of the total injection volume and the single injection volume is determined as the total number of injections, and the total number of injections is 3; the sub-injection volume for the first injection is 80g, the sub-injection volume for the second injection is 80g, and the sub-injection volume for the third injection is 80g.
[0130] (3) Evacuate the cavity of the cell to be injected with liquid to the first negative pressure and maintain it for 55s; wherein the first negative pressure is -90kpa.
[0131] (4) According to the first injection volume, the cell to be injected with liquid is given a first negative pressure in the cavity to obtain the cell to be injected with liquid after one injection; apply a first positive pressure to the cavity of the cell to be injected with liquid after one injection, and inject the cell to be injected with liquid after one injection with a second injection volume according to the second injection volume to obtain the cell to be injected with liquid after two injections; inject the cell to be injected with liquid after two injections with a third injection volume according to the third injection volume to obtain the cell to be injected with liquid after three injections; wherein, the first injection duration is 20s, the second injection duration is 30s, and the third injection duration is 40s; the first positive pressure is 100kPa.
[0132] (5) Evacuate the cavity of the cell to be injected with electrolyte after three injections to a second negative pressure and maintain it under the second negative pressure for a fourth time; after maintaining it under the second negative pressure for a fourth time, apply a third positive pressure to the cavity of the cell to be injected with electrolyte after three injections and maintain it under the third positive pressure for a fifth time to obtain the cell to be injected with electrolyte after one positive and negative pressure cycle treatment; perform a second positive and negative pressure cycle treatment on the cell to be injected with electrolyte after one positive and negative pressure cycle treatment in the same positive and negative pressure cycle treatment method as the first positive and negative pressure cycle treatment to obtain the cell to be injected with electrolyte after two positive and negative pressure cycle treatments; perform a second positive and negative pressure cycle treatment on the cell to be injected with electrolyte after two positive and negative pressure cycle treatments in the same positive and negative pressure cycle treatment method as the first positive and negative pressure cycle treatment. The electrolyte cell undergoes three positive and negative pressure cycles to obtain a electrolyte cell ready for injection after three positive and negative pressure cycles. Following the same positive and negative pressure cycle process as the first cycle, the electrolyte cell ready for injection after three cycles is subjected to four positive and negative pressure cycles to obtain a electrolyte cell ready for injection after four cycles. Following the same positive and negative pressure cycle process as the first cycle, the electrolyte cell ready for injection after four cycles is subjected to five positive and negative pressure cycles to obtain a electrolyte cell ready for injection after five cycles. The second negative pressure is -50 kPa, the third positive pressure is 190 kPa, the fourth cycle duration is 5 s, and the fifth cycle duration is 60 s.
[0133] (6) Apply a second positive pressure to the cavity of the cell to be injected with liquid after five positive and negative pressure cycles, and maintain the second positive pressure for a third time; after maintaining the second positive pressure for a third time, restore the pressure of the cavity of the cell to be injected with liquid from the second positive pressure to the normal pressure to obtain the injected cell; wherein, the second positive pressure is 95 kPa, and the third time is 6 s.
[0134] (7) The electrolyte-filled cells are formed, aged and tested to obtain cells.
[0135] Example 2
[0136] The difference between Example 2 and Example 1 is as follows:
[0137] In step (1), the single injection volume is 60g;
[0138] In step (2), the total number of injections is 4; the sub-injection volume of the first injection is 60g, the sub-injection volume of the second injection is 60g, the sub-injection volume of the third injection is 60g, and the sub-injection volume of the fourth injection is 60g.
[0139] In step (4), after obtaining the cell to be injected with liquid after three injections, the cell to be injected with liquid after three injections is injected with liquid for the fourth time according to the sub-injection volume of the fourth injection, so as to obtain the cell to be injected with liquid after four injections; wherein, the fourth injection time is 50s.
[0140] In step (5), the cavity of the cell to be injected with liquid after four injections is evacuated to a second negative pressure and held under the second negative pressure for a fourth time; after holding under the second negative pressure for a fourth time, a third positive pressure is applied to the cavity of the cell to be injected with liquid after four injections and held under the third positive pressure for a fifth time, thus obtaining the cell to be injected with liquid after one positive and negative pressure cycle treatment.
[0141] Example 3
[0142] The difference between Example 3 and Example 2 is as follows:
[0143] In step (1), the single injection volume is 70g;
[0144] In step (2), the total injection volume cannot be divided evenly by the single injection volume. The integer part of the quotient of the total injection volume and the single injection volume is added by 1 to obtain the total number of injections. The total number of injections is 4. The sub-injection volume of the first injection is 70g, the sub-injection volume of the second injection is 70g, the sub-injection volume of the third injection is 70g, and the sub-injection volume of the fourth injection is 30g.
[0145] Example 4
[0146] The difference between Example 4 and Example 1 is that in step (3), the cavity of the cell to be injected with liquid is evacuated to the first negative pressure and maintained for 50s; wherein the first negative pressure is -95kpa.
[0147] Example 5
[0148] The difference between Example 5 and Example 1 is that in step (3), the cavity of the cell to be injected with liquid is evacuated to the first negative pressure and maintained for 60s; wherein the first negative pressure is -85kpa.
[0149] Example 6
[0150] The difference between Example 6 and Example 1 is that in step (4), the first positive pressure is 95 kPa.
[0151] Example 7
[0152] The difference between Example 7 and Example 1 is that in step (4), the first positive pressure is 105 kPa.
[0153] Example 8
[0154] The difference between Example 8 and Example 1 is that in step (4), the first duration is 10s, the second duration is 20s, and the third duration is 30s.
[0155] Example 9
[0156] The difference between Example 9 and Example 1 is that in step (4), the first duration is 15s, the second duration is 25s, and the third duration is 35s.
[0157] Example 10
[0158] The difference between Example 10 and Example 1 is that:
[0159] In step (5), the cavity of the cell to be injected with liquid after three injections is evacuated to a second negative pressure and held under the second negative pressure for a fourth time; after holding under the second negative pressure for a fourth time, a third positive pressure is applied to the cavity of the cell to be injected with liquid after three injections and held under the third positive pressure for a fifth time, to obtain the cell to be injected with liquid after one positive and negative pressure cycle treatment; the cell to be injected with liquid after one positive and negative pressure cycle treatment is subjected to a second positive and negative pressure cycle treatment in the same positive and negative pressure cycle treatment method as the first positive and negative pressure cycle treatment, to obtain the cell to be injected with liquid after two positive and negative pressure cycle treatments; the cell to be injected with liquid after two positive and negative pressure cycle treatments is subjected to a third positive and negative pressure cycle treatment in the same positive and negative pressure cycle treatment method as the first positive and negative pressure cycle treatment, to obtain the cell to be injected with liquid after three positive and negative pressure cycle treatments.
[0160] In step (6), a second positive pressure is applied to the cavity of the cell to be injected with liquid after three positive and negative pressure cycles, and the pressure is maintained for a third time under the second positive pressure. After maintaining the pressure under the second positive pressure for a third time, the pressure of the cavity of the cell to be injected with liquid after three positive and negative pressure cycles is restored from the second positive pressure to the normal pressure, and the cell is injected with liquid.
[0161] Example 11
[0162] The difference between Example 11 and Example 1 is that:
[0163] In step (5), the cavity of the cell to be injected with liquid after three injections is evacuated to a second negative pressure and held under the second negative pressure for a fourth time; after holding under the second negative pressure for a fourth time, a third positive pressure is applied to the cavity of the cell to be injected with liquid after three injections and held under the third positive pressure for a fifth time, resulting in a cell to be injected with liquid after one positive and negative pressure cycle treatment; the cell to be injected with liquid after one positive and negative pressure cycle treatment is subjected to a second positive and negative pressure cycle treatment in the same positive and negative pressure cycle treatment method as the first positive and negative pressure cycle treatment, resulting in a cell to be injected with liquid after two positive and negative pressure cycles; the cell to be injected with liquid after two positive and negative pressure cycles is subjected to a third positive and negative pressure cycle treatment in the same positive and negative pressure cycle treatment method as the first positive and negative pressure cycle treatment, resulting in a cell to be injected with liquid after three positive and negative pressure cycles; the cell to be injected with liquid after three positive and negative pressure cycles is subjected to a fourth positive and negative pressure cycle treatment in the same positive and negative pressure cycle treatment method as the first positive and negative pressure cycle treatment, resulting in a cell to be injected with liquid after four positive and negative pressure cycles.
[0164] In step (6), a second positive pressure is applied to the cavity of the cell to be injected with liquid after four positive and negative pressure cycles, and the pressure is maintained for a third time under the second positive pressure. After maintaining the pressure under the second positive pressure for a third time, the pressure of the cavity of the cell to be injected with liquid after four positive and negative pressure cycles is restored from the second positive pressure to the normal pressure, and the cell is injected with liquid.
[0165] Example 12
[0166] The difference between Example 12 and Example 1 is that in step (5), the second negative pressure is -40 kPa and the fourth duration is 6 s.
[0167] Example 13
[0168] The difference between Example 13 and Example 1 is that in step (5), the second negative pressure is -45 kPa and the fourth duration is 5.5 s.
[0169] Example 14
[0170] The difference between Example 14 and Example 1 is that in step (5), the third positive pressure is 210 kPa and the fifth duration is 50 s.
[0171] Example 15
[0172] The difference between Example 15 and Example 1 is that in step (5), the third positive pressure is 200 kPa and the fifth duration is 55 s.
[0173] Example 16
[0174] The difference between Example 16 and Example 1 is that in step (6), the second positive pressure is 105 kPa and the third duration is 5 s.
[0175] Example 17
[0176] The difference between Example 17 and Example 1 is that in step (6), the second positive pressure is 100 kPa and the third duration is 5.5 s.
[0177] Comparative Example 1
[0178] The difference between Comparative Example 1 and Example 1 is as follows:
[0179] In step (1), determining the volume of a single injection is not included;
[0180] Step (2) is excluded;
[0181] In step (4), a first positive pressure is applied to the cavity of the cell to be injected with liquid, and the cell to be injected with liquid is injected for the first time according to the total amount of liquid injected, so as to obtain the cell to be injected with liquid after one injection; wherein, the first positive pressure is 0 kPa;
[0182] In step (5), a third positive pressure is applied to the cavity of the cell to be injected with liquid after one injection, and the third positive pressure is maintained for a fifth time. After maintaining the third positive pressure for a fifth time, the cavity of the cell to be injected with liquid after one injection is evacuated to a second negative pressure, and the second negative pressure is maintained for a fourth time, resulting in a cell to be injected with liquid after one positive and negative pressure cycle treatment. Following the same positive and negative pressure cycle treatment method as the one positive and negative pressure cycle treatment, the cell to be injected with liquid after one positive and negative pressure cycle treatment is subjected to 15 positive and negative pressure cycle treatments, resulting in a cell to be injected with liquid after 15 positive and negative pressure cycle treatments. Among them, the second negative pressure is -50 kPa, the third positive pressure is 190 kPa, the fourth time is 5 s, and the fifth time is 60 s.
[0183] Performance testing methods:
[0184] Charge-discharge cycle test: The Hangke capacity test cabinet was used to perform 0.6C charge / 0.5C discharge cycle test (50 times) and the appearance morphology of the electrode was recorded.
[0185] The battery cells obtained in Example 1 and Comparative Example 1 were subjected to charge-discharge cycle tests, and the test results are as follows: Figure 3 and Figure 4 As shown. Figure 3 As shown, after charge-discharge cycle testing, the electrode plates of the battery cell obtained in Example 1 showed no visible dark marks or wrinkles; Figure 4 As shown, after performing charge-discharge cycle tests on the battery cell obtained in Example 1, a large number of visible wrinkles were found at the electrode interface.
[0186] Therefore, it can be seen that the battery cell obtained by the liquid injection method provided in the embodiments of the present invention has no wrinkles on the electrode during the charging and discharging process, which avoids the problems of lithium plating and black spots at the electrode wrinkles during subsequent charging and discharging processes, improves the safety of the battery cell, and extends the cycle life of the battery cell.
[0187] In summary, the liquid injection method provided by the embodiments of the present invention reduces or avoids electrode wrinkling problems, improves cell safety, extends cell cycle life, and also helps to improve electrode wetting efficiency, reduce the number of positive and negative pressure cycles, shorten liquid injection time, and reduce cell manufacturing costs.
[0188] The above provides a detailed description of the liquid injection method, battery cell, and electrical device provided by the present invention. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.
Claims
1. A method for injecting liquid, characterized in that, The method includes: Determine the total injection volume and single injection volume corresponding to the battery cell to be injected; the single injection volume is less than or equal to 80g, and the total injection volume is greater than the single injection volume; Based on the total injection volume and the single injection volume, determine the total number of injections and the sub-injection volume for each injection. The cavity of the cell to be injected with liquid is evacuated to a first negative pressure and maintained for 50 to 60 seconds. According to the sub-injection volume, the first injection is performed into the cell to be injected with liquid under the first negative pressure in the cavity, to obtain the cell to be injected with liquid after one injection; the injection time of the first injection is the first time. A first positive pressure is applied to the cavity of the cell to be injected after the first injection, and the cell to be injected after the first injection is injected for the nth time according to the sub-injection volume, to obtain a cell to be injected after n injections; n is an integer greater than 1 and less than or equal to the total number of injections, the injection time of the nth injection is the nth time, and the nth time is greater than or equal to the first time; When n equals the total number of injection cycles, the cells to be injected with liquid are subjected to positive and negative pressure cycling after the n injection cycles to obtain the injected cells.
2. The method according to claim 1, characterized in that, The nth duration is t+10(n-1)s; where t is the first duration.
3. The method according to claim 1, characterized in that, The first duration is 10s to 20s.
4. The method according to claim 1, characterized in that, The first negative pressure is -95 kPa to -85 kPa; the first positive pressure is 95 kPa to 105 kPa.
5. The method according to claim 1, characterized in that, The step of determining the total number of injections and the sub-injection volume for each injection based on the total injection volume and the single injection volume includes: When the total injection volume is divisible by the single injection volume, the quotient of the total injection volume and the single injection volume is determined as the total number of injections, and the sub-injection volume of each injection is the single injection volume. If the total injection volume cannot be divided evenly by the single injection volume, add 1 to the integer part of the quotient of the total injection volume and the single injection volume to obtain the total number of injections. The sub-injection volume of each injection before the last injection is the single injection volume, and the sub-injection volume of the last injection is less than the single injection volume.
6. The method according to claim 1, characterized in that, The single injection volume is 60g to 80g.
7. The method according to claim 1, characterized in that, When n equals the total number of injection cycles, the electrolyte cell after n injection cycles is subjected to positive and negative pressure cycling to obtain an electrolyte-filled electrolyte cell, including: The cell to be injected with electrolyte after n injections is subjected to m positive and negative pressure cycles to obtain a cell to be injected with electrolyte after m positive and negative pressure cycles; m is any integer from 3 to 5; A second positive pressure is applied to the cavity of the cell to be injected with liquid after m cycles of positive and negative pressure treatment, and the second positive pressure is maintained for a third duration. After maintaining the second positive pressure for a third time, the pressure of the cavity of the cell to be injected with liquid is restored from the second positive pressure to the normal pressure after the m positive and negative pressure cycles, thus obtaining the liquid-injected cell; The second positive pressure is 95 kPa to 105 kPa, and the third duration is 5 s to 6 s.
8. The method according to claim 7, characterized in that, The process of performing m positive and negative pressure cycles on the battery cell after n injections to obtain a battery cell after m positive and negative pressure cycles includes: When n equals the total number of injections, the cavity of the cell to be injected after n injections is evacuated to a second negative pressure and maintained under the second negative pressure for a fourth time. After maintaining the second negative pressure for a fourth time, a third positive pressure is applied to the cavity of the cell to be injected with liquid after the nth injection, and the third positive pressure is maintained for a fifth time to obtain the cell to be injected with liquid after one positive and negative pressure cycle treatment. The second negative pressure is -50 kPa to -40 kPa, the third positive pressure is 190 kPa to 210 kPa, the fourth duration is 5 s to 6 s, and the fifth duration is 50 s to 60 s.
9. A battery cell, characterized in that, The battery cell includes an electrolyte, which is injected into the battery cell by the injection method as described in any one of claims 1 to 8.
10. An electrical appliance, characterized in that, The electrical device includes the battery cell as described in claim 9, wherein the battery cell serves as the power supply for the electrical device.