Gradient infiltration liquid injection method and liquid injection system based on dynamic temperature regulation and control, and lithium ion battery

Abstract

The invention provides a gradient infiltration liquid injection method and system based on dynamic temperature regulation and control and a lithium ion battery, and relates to the field of lithium ion battery preparation. The method comprises the following steps: a preheating and low-viscosity filling stage: injecting an electrolyte with a first temperature and a viscosity of eta 1, wherein the first temperature is higher than the environment temperature; a gradient guide and viscosity recovery permeation stage: after the electrolyte is injected, establishing and maintaining a space temperature field in the battery to enable different areas in the battery to be at different temperatures so as to form a temperature gradient, and guiding the electrolyte to flow by the temperature gradient; in the flowing process, the temperature of the electrolyte is reduced from the first temperature, and the viscosity of the electrolyte is increased to eta 2 from eta 1; and a balancing and stabilizing stage: uniformly adjusting the overall temperature of the battery to a target temperature, and completing infiltration. According to the method, uniform and stable infiltration of the electrolyte in the battery is ensured, so that the interface performance and consistency of the battery are improved.

Description

Technical Field

[0001] This application relates to the field of lithium-ion battery preparation, and in particular to a gradient wetting liquid injection method and liquid injection system based on dynamic temperature control, and a lithium-ion battery. Background Technology

[0002] Electrolyte filling is a core step in lithium-ion battery production, and its wetting quality directly affects the battery's interface stability, performance consistency, and lifespan. As battery technology advances towards higher energy density and demands for higher safety and wider temperature adaptability increase, electrolyte formulations are becoming increasingly complex, commonly incorporating high-concentration lithium salts, polymer additives, and high-viscosity functional solvents, leading to a significant increase in the overall dynamic viscosity of the electrolyte. In conventional production environments, especially at lower temperatures, electrolyte fluidity deteriorates further, exacerbating the difficulty of the wetting process. The vacuum filling technology widely used in industry is essentially a passive wetting mechanism, relying primarily on capillary force and external pressure difference to drive electrolyte penetration. While this process can maintain basic efficiency for low-viscosity systems, it exhibits serious limitations when dealing with modern high-viscosity electrolytes: the wetting rate is drastically reduced, leading to longer production cycles and significantly constrained capacity. Although some technical solutions attempt to reduce the initial viscosity of the electrolyte through preheating, these methods typically only implement global, instantaneous heating, limiting their effectiveness to the initial filling stage. This simple heating strategy cannot effectively address the deep penetration requirements of the electrolyte within the microporous structure of the electrode. Furthermore, during the rapid cooling process after electrolyte injection, the viscosity rebound is often accompanied by volume shrinkage, which can easily lead to new problems such as interfacial desorption or air gap formation, thereby compromising the long-term reliability of the battery. Therefore, there is an urgent need to develop an innovative method that can actively regulate temperature distribution and dynamically optimize wetting kinetics to solve the penetration bottleneck of high-viscosity electrolytes in complex microstructures.

[0003] To address the aforementioned issues, existing technologies urgently need improvement. Summary of the Invention

[0004] The purpose of this application is to provide a gradient wetting liquid injection method and system based on dynamic temperature control, and a lithium-ion battery, to solve the above-mentioned problems.

[0005] To achieve the above objectives, this application adopts the following technical solution: This application provides a gradient infiltration injection method based on dynamic temperature control, including: Preheating and low viscosity filling stage: Injecting an electrolyte with a first temperature and a viscosity of η1, wherein the first temperature is greater than the ambient temperature; Gradient-guided and viscosity recovery penetration stage: After the electrolyte is injected, a spatial temperature field is established and maintained inside the battery, so that different regions inside the battery are at different temperatures, thereby forming a temperature gradient. The temperature gradient guides the flow of the electrolyte. During the flow, the electrolyte temperature decreases from the first temperature, and the viscosity of the electrolyte increases from η1 to η2. The enhanced capillary force due to the viscosity recovery promotes the penetration of the electrolyte into the depth of the micropores of the electrode. Balance and stabilization phase: The overall temperature of the battery is uniformly adjusted to the target temperature to complete the immersion process.

[0006] Optionally, the electrolyte has a dynamic viscosity greater than 5 mPa·s at 25°C.

[0007] Optionally, the temperature gradient is a vertical gradient that decreases from the injection port to the bottom along the thickness direction of the battery; or, A radial gradient that decreases from the center of the battery towards the edge.

[0008] Optionally, the spatial temperature field is established and maintained by controlling the temperature of different areas of the clamp holding the battery.

[0009] Optionally, the first temperature is 40-70°C.

[0010] Optionally, the target temperature is 60-80℃.

[0011] Optionally, η1 is 4-6 mPa·s.

[0012] Optionally, η2 is 1-3 mPa·s.

[0013] This application also provides a dynamic temperature-controlled injection system for implementing a gradient wetting injection method based on dynamic temperature control, comprising: A precision temperature-controlled electrolyte injection unit includes an injection needle, a heating element integrated into the injection needle, and a first temperature sensor for heating the flowing electrolyte in real time and controlling it at the first temperature. The intelligent temperature field management unit includes a clamp for holding the battery, the clamp integrating a zoned temperature control module and a second temperature sensor for establishing and maintaining the spatial temperature field on the battery; The central controller is electrically connected to the first temperature sensor, the second temperature sensor, the heating element, and the zone temperature control module. It is used to receive temperature signals and control the working state of the heating element and the zone temperature control module according to a preset program to execute the liquid injection method.

[0014] Optionally, the zoned temperature control module is a semiconductor cooling chip or a microfluidic circulation pipeline integrated into the fixture.

[0015] Optionally, the heating element of the injection needle is a thin-film heater wrapped around the outer wall of the needle or embedded in the needle tube wall.

[0016] This application also provides a lithium-ion battery, which is prepared using the gradient wetting method based on dynamic temperature control.

[0017] Compared with the prior art, the beneficial effects of this application include: The wetting method provided in this application achieves rapid filling of macroscopic channels through initial heating to reduce viscosity, followed by enhanced capillary penetration into micropores through subsequent cooling-induced viscosity recovery and temperature gradient guidance. This achieves an optimal wetting path of "fast first, deep later," significantly shortening the wetting time (by 30%-70%) and greatly improving the wetting uniformity within the cell (especially in the thick electrode and middle region of stacked cells). Uniform wetting ensures uniform SEI film formation and reduces interfacial impedance, thereby contributing to improved first-cycle charge / discharge efficiency, rate performance, and cycle life. By dynamically controlling the electrolyte temperature and the internal temperature field of the battery, this method effectively solves the problems of slow wetting speed, insufficient penetration power, and potential interfacial defects associated with high-viscosity electrolytes in traditional electrolyte injection processes. This method achieves rapid initial filling of the electrolyte, actively guides electrolyte flow through temperature gradients, and utilizes viscosity recovery to enhance capillary forces, promoting deep penetration of the electrolyte into the electrode micropores. Ultimately, it ensures uniform and stable wetting of the electrolyte within the battery, thereby improving the battery's interfacial performance and consistency. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation on the scope of this application.

[0019] Figure 1 A schematic diagram of the structure of the dynamic temperature-controlled injection system for implementing the gradient wetting injection method based on dynamic temperature control, as provided in Example 1; Figure 2 This is a schematic diagram illustrating the changes in electrolyte viscosity and temperature over time / space during the three stages of the gradient wetting injection method based on dynamic temperature control, as provided in the embodiment. Figure 3 This is a schematic diagram comparing the wetting effect of high-viscosity electrolyte in Example 2 and Comparative Example 1. Detailed Implementation

[0020] As used in this article: "Prepared from" is synonymous with "comprising". The terms "comprising", "including", "having", "containing", or any other variations thereof as used herein are intended to cover non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.

[0021] The conjunction "composed of..." excludes any unspecified elements, steps, or components. If used in a claim, this phrase makes the claim closed, excluding materials other than those described, except for associated conventional impurities. When the phrase "composed of..." appears in a clause of the body of a claim rather than immediately following it, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0022] When a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “1–5” is disclosed, the described range should be interpreted as including ranges “1–4”, “1–3”, “1–2”, “1–2 and 4–5”, “1–3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range.

[0023] In these embodiments, unless otherwise specified, the portions and percentages are all by weight.

[0024] "Parts by mass" refers to the basic unit of measurement that expresses the mass ratio of multiple components. One part can represent any unit mass, such as 1g or 2.689g. If we say that component A has "a" parts by mass and component B has "b" parts by mass, it means the ratio of the mass of component A to the mass of component B is a:b. Alternatively, it can mean that the mass of component A is aK and the mass of component B is bK (where K is any number representing a multiplier). It is important to understand that, unlike parts by mass, the sum of the mass parts of all components is not limited to 100 parts.

[0025] "And / or" is used to indicate that one or both of the described situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0026] To better explain the technical solution provided in this application, the technical solution provided in this application will be described in general before the specific implementation.

[0027] Traditional lithium-ion battery electrolyte filling processes, especially vacuum filling technology, suffer from slow wetting speed and low production efficiency when handling high-viscosity electrolytes. Simple overall heating solutions can only temporarily reduce viscosity and cannot effectively solve the problem of insufficient penetration power of electrolyte into the deep micropores of the electrodes, and may also cause new interface defects due to rapid cooling. These limitations restrict the improvement of battery performance and production efficiency.

[0028] In this regard, firstly, this application provides a gradient wetting injection method based on dynamic temperature control, comprising: Preheating and low viscosity filling stage: Injecting an electrolyte with a first temperature and a viscosity of η1, wherein the first temperature is greater than the ambient temperature; Gradient-guided and viscosity recovery penetration stage: After the electrolyte is injected, a spatial temperature field is established and maintained inside the battery, so that different regions inside the battery are at different temperatures, thereby forming a temperature gradient. The temperature gradient guides the flow of the electrolyte. During the flow, the electrolyte temperature decreases from the first temperature, and the viscosity of the electrolyte increases from η1 to η2. The enhanced capillary force due to the viscosity recovery promotes the penetration of the electrolyte into the depth of the micropores of the electrode. Balance and stabilization phase: The overall temperature of the battery is uniformly adjusted to the target temperature to complete the immersion process.

[0029] In one optional embodiment, the electrolyte has a dynamic viscosity greater than 5 mPa·s at 25°C.

[0030] In an optional implementation, the temperature gradient is a vertical gradient that decreases from the injection port to the bottom along the thickness direction of the battery. or, A radial gradient that decreases from the center of the battery towards the edge.

[0031] In an alternative implementation, the spatial temperature field is established and maintained by controlling the temperature of different areas of the clamp holding the battery.

[0032] In one alternative implementation, the first temperature is 40-70°C.

[0033] Optionally, the first temperature can be 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, or any value between 40℃ and 70℃.

[0034] In one optional implementation, the target temperature is 60-80°C.

[0035] In an optional implementation, η1 is 6-8 mPa·s.

[0036] In an alternative implementation, η2 is 1-3 mPa·s.

[0037] It is understood that the electrolyte injection method in this embodiment includes three main stages, which are designed to optimize the electrolyte wetting process.

[0038] During the preheating and low-viscosity filling stage, the electrolyte is heated to a first temperature before or during injection into the battery. This first temperature is set above ambient temperature to effectively reduce the electrolyte viscosity to η1. For example, the electrolyte can be preheated using an external heating device or heated while flowing through the injection channel. Heating methods can include resistance wire heating, infrared heating, or hot air circulation heating, among others. By reducing the electrolyte viscosity, good fluidity of the electrolyte can be ensured during battery injection, thereby achieving rapid and efficient initial filling.

[0039] During the gradient-guided and viscosity-rebound penetration stage, after the electrolyte is injected into the battery, a spatial temperature field is established and maintained inside the battery. This spatial temperature field causes different regions inside the battery to be at different temperatures, thus forming a temperature gradient. This temperature gradient is designed to actively guide the flow direction of the electrolyte inside the battery. For example, this spatial temperature field can be created and maintained by setting multiple independent heating or cooling zones outside the battery, or by introducing media with different temperatures inside the battery. As the electrolyte flows along the temperature gradient, its temperature gradually decreases from the first temperature, causing the electrolyte viscosity to gradually increase from η1 to η2. The increase in viscosity enhances the capillary force of the electrolyte, thereby promoting deeper penetration of the electrolyte into the micropores of the electrodes.

[0040] During the equilibrium and stabilization phase, once the electrolyte penetration process is largely complete, the overall battery temperature is uniformly adjusted to the target temperature. This adjustment process aims to eliminate temperature gradients within the battery, bringing the entire battery to a stable temperature state, thereby ensuring a uniform and stable final wetting effect of the electrolyte within the battery. For example, this target temperature can be achieved by placing the battery in a constant-temperature environment, or by subjecting the battery to overall heating or cooling.

[0041] The electrolyte injection method in this embodiment effectively solves the problems of slow wetting speed, insufficient penetration power, and potential interface defects caused by high-viscosity electrolytes in traditional injection processes by dynamically controlling the electrolyte temperature and the internal temperature field of the battery. This method achieves rapid initial filling of the electrolyte, actively guides electrolyte flow through a temperature gradient, and utilizes viscosity recovery to enhance capillary forces, promoting deep penetration of the electrolyte into the micropores of the electrodes. Ultimately, it ensures uniform and stable wetting of the electrolyte within the battery, thereby improving the battery's interface performance and consistency.

[0042] Secondly, this application also provides a dynamic temperature-controlled injection system for implementing a gradient wetting injection method based on dynamic temperature control, comprising: A precision temperature-controlled electrolyte injection unit includes an injection needle, a heating element integrated into the injection needle, and a first temperature sensor for heating the flowing electrolyte in real time and controlling it at the first temperature. The intelligent temperature field management unit includes a clamp for holding the battery, the clamp integrating a zoned temperature control module and a second temperature sensor for establishing and maintaining the spatial temperature field on the battery; The central controller is electrically connected to the first temperature sensor, the second temperature sensor, the heating element, and the zone temperature control module. It is used to receive temperature signals and control the working state of the heating element and the zone temperature control module according to a preset program to execute the liquid injection method.

[0043] In an optional implementation, the zoned temperature control module is a semiconductor cooling chip or a microfluidic circulation pipeline integrated within the fixture.

[0044] In an optional embodiment, the heating element of the injection needle is a thin-film heater wrapped around the outer wall of the needle or embedded in the needle tube wall.

[0045] Thirdly, this application also provides a lithium-ion battery prepared using the gradient wetting method based on dynamic temperature control.

[0046] The implementation schemes of this application will be described in detail below with reference to specific embodiments. However, those skilled in the art will understand that the following embodiments are only for illustrating this application and should not be regarded as limiting the scope of this application. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments used without specified manufacturers are all conventional products that can be purchased commercially.

[0047] Example 1 This embodiment provides a dynamic temperature-controlled injection system for implementing a gradient wetting injection method based on dynamic temperature regulation, as shown in the schematic diagram below. Figure 1 As shown, it specifically includes: A precision temperature-controlled electrolyte injection unit includes an injection needle, a heating element integrated into the injection needle, and a first temperature sensor for heating the flowing electrolyte in real time and controlling it at the first temperature.

[0048] The intelligent temperature field management unit includes a clamp for holding the battery. The clamp integrates a zoned temperature control module and a second temperature sensor for establishing and maintaining the spatial temperature field on the battery. The zoned temperature control module is a semiconductor refrigeration chip.

[0049] The central controller is electrically connected to the first temperature sensor, the second temperature sensor, the heating element, and the zone temperature control module. It is used to receive temperature signals and control the working state of the heating element and the zone temperature control module according to a preset program to execute the gradient immersion injection method based on dynamic temperature regulation. The heating element of the injection needle is a thin-film heater embedded in the needle tube wall.

[0050] Example 2 This embodiment provides a gradient infiltration injection method based on dynamic temperature control, the specific steps of which are as follows: Preheating and low-viscosity filling stage: The central controller sets the target temperature of the injection needle to 45℃. The electrolyte flows through the needle at a flow rate of 5mL / s and is heated to 45℃ in real time before being injected into the battery. At this time, the electrolyte viscosity is significantly reduced to η1 (6mPa·s), and then injected into the battery casing.

[0051] Gradient-guided and viscosity-recovery penetration stage: Immediately after electrolyte injection, the intelligent temperature field management unit is activated: the sealing areas on both sides of the battery are cooled and maintained at 25°C through a semiconductor cooling chip; the central area of ​​the battery is heated and maintained at 35°C through a heating film; the central controller, based on feedback from the second temperature sensor, performs closed-loop control of the temperature in each area, forming a radial temperature gradient that decreases from the center to the edge inside the battery. Driven by this temperature gradient, the electrolyte spreads directionally from the high-temperature area in the center to the low-temperature area at the edge; during the flow, the electrolyte temperature gradually decreases, and the viscosity decreases from η1 to 2. mPa·s (η2), thereby increasing the capillary force and continuously pulling the electrolyte into the depths of the electrode micropores.

[0052] Balance and stabilization phase: After the gradient maintenance is completed, the central controller will uniformly bring the entire battery to the target temperature of 35°C, completing the final immersion and interface stabilization.

[0053] This embodiment also provides a lithium-ion battery: The battery is a 5Ah aluminum-cased wound soft-pack battery with lithium iron phosphate as the positive electrode, graphite as the negative electrode, and a double-sided ceramic-coated separator.

[0054] The electrolyte was a base electrolyte (1M LiPF6, solvent EC / EMC / DMC, volume ratio 1:1:1) with 2wt% vinylene carbonate (VC) film-forming additive added. Its dynamic viscosity was measured to be approximately 8 mPa·s at 25°C using a rotational viscometer.

[0055] The schematic diagram of electrolyte viscosity and temperature changes over time / space during the three stages of electrolyte injection is shown below. Figure 2 As shown in the diagram. A comparison of the wetting effects on high-viscosity electrolytes is presented. Figure 3 As shown on the right.

[0056] Example 3 This embodiment provides a gradient infiltration injection method based on dynamic temperature control, the specific steps of which are as follows: Preheating and low-viscosity filling stage: The central controller sets the target temperature of the injection needle to 55℃. The electrolyte flows through the needle at a flow rate of 5mL / s and is heated to 55℃ in real time before being injected into the battery. At this time, the electrolyte viscosity is significantly reduced to η1 (5mPa·s), and then injected into the battery casing.

[0057] Gradient-guided and viscosity-recovery penetration stage: Immediately after electrolyte injection, the intelligent temperature field management unit is activated: the sealing areas on both sides of the battery are cooled and maintained at 30°C through a semiconductor cooling chip; the central area of ​​the battery is heated and maintained at 45°C through a heating film; the central controller, based on feedback from the second temperature sensor, performs closed-loop control of the temperature in each area, forming a radial temperature gradient that decreases from the center to the edge inside the battery. Driven by this temperature gradient, the electrolyte spreads directionally from the high-temperature central area to the low-temperature edge area; during the flow process, the electrolyte temperature gradually decreases, and the viscosity decreases from η1 to 2 mPa·s (η2), thereby increasing the capillary force and continuously pulling the electrolyte into the depths of the electrode micropores.

[0058] Balance and stabilization phase: After the gradient maintenance is completed, the central controller will uniformly bring the entire battery to the target temperature of 45°C, completing the final immersion and interface stabilization.

[0059] This embodiment also provides a lithium-ion battery, using the same materials as in Embodiment 2.

[0060] Example 4 This embodiment provides a gradient infiltration injection method based on dynamic temperature control, the specific steps of which are as follows: Preheating and low-viscosity filling stage: The central controller sets the target temperature of the injection needle to 65℃. The electrolyte flows through the needle at a flow rate of 5mL / s and is heated to 65℃ in real time before being injected into the battery. At this time, the electrolyte viscosity is significantly reduced to η1 (4mPa·s), and then injected into the battery casing.

[0061] Gradient-guided and viscosity-recovery penetration stage: Immediately after electrolyte injection, the intelligent temperature field management unit is activated: the sealing areas on both sides of the battery are cooled and maintained at 55°C through a semiconductor cooling chip; the central area of ​​the battery is heated and maintained at 55°C through a heating film; the central controller, based on feedback from the second temperature sensor, performs closed-loop control of the temperature in each area, forming a radial temperature gradient that decreases from the center to the edge inside the battery. Driven by this temperature gradient, the electrolyte spreads directionally from the high-temperature central area to the low-temperature edge area; during the flow process, the electrolyte temperature gradually decreases, and the viscosity decreases from η1 to 2 mPa·s (η2), thereby increasing the capillary force and continuously pulling the electrolyte into the depths of the electrode micropores.

[0062] Balance and stabilization phase: After the gradient maintenance is completed, the central controller will uniformly bring the entire battery to the target temperature of 55°C, completing the final immersion and interface stabilization.

[0063] This embodiment also provides a lithium-ion battery, using the same materials as in Embodiment 2.

[0064] Comparative Example 1 This comparative example provides a traditional vacuum liquid injection method, the specific steps of which are as follows: Sealing and vacuuming: Seal the battery casing / fill port and remove air and moisture from inside the battery cell. Objective: To create negative pressure and eliminate air resistance.

[0065] Electrolyte injection (negative pressure electrolyte absorption): Electrolyte is injected under vacuum. At this time, the battery is under negative pressure, and the electrolyte will be "absorbed" into the pores of the electrode and separator, rather than being added slowly by gravity.

[0066] Pressure holding / pressure impregnation: After injection, maintain a vacuum or apply slight pressure to allow the electrolyte to fully penetrate the micropores. Purpose: To remove residual air bubbles and ensure uniform impregnation.

[0067] Return to normal pressure and immediately seal / tighten to prevent electrolyte backflow or air intake.

[0068] This comparative example also provides a lithium-ion battery, using the same materials as in Example 2.

[0069] A comparative diagram showing the wetting effect on high-viscosity electrolytes is shown below. Figure 3 As shown on the left.

[0070] Comparative Example 2 This comparative example provides a method for injecting electrolyte at room temperature without setting a temperature gradient.

[0071] This comparative example also provides a lithium-ion battery, using the same materials as in Example 2.

[0072] Comparative Example 3 This comparative example provides a gradient infiltration injection method based on dynamic temperature control. The overall steps are as follows: Preheating and low-viscosity filling stage: The central controller sets the target temperature of the injection needle to 30℃. The electrolyte flows through the needle at a flow rate of 5mL / s and is heated to 70℃ in real time before being injected into the battery. At this time, the electrolyte viscosity is significantly reduced to η1 (5mPa·s), and then injected into the battery casing.

[0073] Gradient-guided and viscosity recovery penetration stage: Immediately after electrolyte injection, the intelligent temperature field management unit is activated: the sealing areas on both sides of the battery are cooled and maintained at 30°C through a semiconductor cooling chip; the central area of ​​the battery is heated and maintained at 70°C through a heating film; the central controller controls the temperature of each area in a closed loop based on feedback from the second temperature sensor, forming a radial temperature gradient that decreases from the center to the edge inside the battery. Driven by this temperature gradient, the electrolyte spreads directionally from the high-temperature area in the center to the low-temperature area at the edge; during the flow, the electrolyte temperature gradually decreases, and the viscosity decreases from η1 to 2 mPa·s (η2), and the capillary force increases accordingly, continuously pulling the electrolyte into the depths of the electrode micropores.

[0074] Balance and stabilization phase: After the gradient maintenance is completed, the central controller will uniformly bring the entire battery to the target temperature of 75°C, completing the final immersion and interface stabilization.

[0075] This comparative example also provides a lithium-ion battery, using the same materials as in Example 2.

[0076] The electrical performance of the lithium-ion batteries prepared in the examples and comparative examples is shown in Table 1: Table 1 shows the electrical performance of the lithium-ion batteries provided in the examples and comparative examples.

[0077] As shown in Table 1, the data on first-efficiency performance, rate performance, and cycle capacity retention between the examples and comparative examples show that the electrolyte injection temperature has a significant impact on battery performance in the early temperature-gradient electrolyte injection comparison. Too high an electrolyte injection temperature will lead to an increase in side reactions inside the battery during later charging and discharging. Too low a temperature will result in high electrolyte viscosity and poor penetration, leading to incomplete wetting of the internal center and inducing the risk of lithium plating. Therefore, the electrolyte injection stage must be controlled at a suitable temperature without affecting the battery electrolyte itself.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

[0079] Furthermore, those skilled in the art will understand that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of this application and form different embodiments. For example, in the foregoing claims, any of the claimed embodiments can be used in any combination. The information disclosed in this background section is intended only to enhance the understanding of the general background of this application and should not be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

Claims

1. A gradient wetting injection method based on dynamic temperature control, characterized in that, include: Preheating and low viscosity filling stage: Injecting an electrolyte with a first temperature and a viscosity of η1, wherein the first temperature is greater than the ambient temperature; Gradient guidance and viscosity recovery penetration stage: After the electrolyte is injected, a spatial temperature field is established and maintained inside the battery, so that different regions inside the battery are at different temperatures, thereby forming a temperature gradient, which guides the flow of electrolyte. During the flow process, the electrolyte temperature decreases from the first temperature, and the viscosity of the electrolyte increases from η1 to η2. The increased viscosity enhances the capillary force, promoting the penetration of the electrolyte into the depth of the micropores of the electrode. Balance and stabilization phase: The overall temperature of the battery is uniformly adjusted to the target temperature to complete the immersion process.

2. The gradient wetting injection method based on dynamic temperature control according to claim 1, characterized in that, The electrolyte has a dynamic viscosity greater than 5 mPa·s at 25°C.

3. The gradient wetting injection method based on dynamic temperature control according to claim 1, characterized in that, The temperature gradient is a vertical gradient that decreases from the injection port to the bottom along the thickness direction of the battery. or, A radial gradient that decreases from the center of the battery towards the edge.

4. The gradient wetting injection method based on dynamic temperature control according to claim 1, characterized in that, The spatial temperature field is established and maintained by controlling the temperature of different areas of the clamp holding the battery.

5. The gradient wetting injection method based on dynamic temperature control according to claim 1, characterized in that, At least one of the following conditions must be met: a. The first temperature is 40-70℃; b. The target temperature is 60-80℃.

6. The gradient wetting injection method based on dynamic temperature control according to any one of claims 1-5, characterized in that, At least one of the following conditions must be met: c.η1 is 4-6 mPa·s; d.η2 is 1-3 mPa.s.

7. A dynamic temperature-controlled liquid injection system for implementing the method according to any one of claims 1-6, characterized in that, include: A precision temperature-controlled electrolyte injection unit includes an injection needle, a heating element integrated into the injection needle, and a first temperature sensor for heating the flowing electrolyte in real time and controlling it at the first temperature. The intelligent temperature field management unit includes a clamp for holding the battery, the clamp integrating a zoned temperature control module and a second temperature sensor for establishing and maintaining the spatial temperature field on the battery; The central controller is electrically connected to the first temperature sensor, the second temperature sensor, the heating element, and the zone temperature control module. It is used to receive temperature signals and control the working state of the heating element and the zone temperature control module according to a preset program to execute the liquid injection method.

8. The dynamic temperature-controlled injection system according to claim 7, characterized in that, The zoned temperature control module is a semiconductor cooling chip or a microfluidic circulation pipeline integrated into the fixture.

9. The dynamic temperature-controlled injection system according to claim 7, characterized in that, The heating element of the injection needle is a thin-film heater that is wrapped around the outer wall of the needle or embedded in the needle tube wall.

10. A lithium-ion battery, characterized in that, It is prepared using the gradient immersion injection method based on dynamic temperature control as described in any one of claims 1-6.

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