Irradiation-modified lithium battery separator and preparation method and device thereof

Abstract

This disclosure provides an irradiation-modified lithium-ion battery separator and its preparation method and apparatus, relating to the field of lithium-ion battery technology. The apparatus includes: an electron beam irradiation modification module for conveying the single-cell impregnated lithium-ion battery separator to an electron beam irradiation area and real-time monitoring of the separator's temperature and tension; an electron beam irradiation module for applying electron beam irradiation to the single-cell impregnated lithium-ion battery separator after passing through a cooling module support area; a cooling module for maintaining the single-cell impregnated lithium-ion battery separator in a cyclic cooling state during electron beam irradiation; and a controller for controlling the cooling module to maintain the cyclic cooling state. The controller adjusts one or more of the following parameters based on detection signals from multiple sensors: the conveying state of the single-cell impregnated lithium-ion battery separator, electron beam irradiation output parameters, and irradiation environment parameters, thereby completing electron beam irradiation modification under preset irradiation process conditions. This disclosure can improve the thermal stability and wetting performance of the separator.

Description

Technical Field

[0001] This disclosure relates to the field of lithium battery technology, and more specifically, to an apparatus for preparing an irradiated modified lithium battery separator, a method for preparing an irradiated modified lithium battery separator, and an irradiated modified lithium battery separator. Background Technology

[0002] Lithium-ion battery separators are used to isolate the positive and negative electrodes and provide lithium-ion transport channels. Their performance directly affects the battery's rate performance, cycle stability, and safety. Although existing polyethylene, polypropylene, and their composite separators have good mechanical strength and chemical stability, their low polarity and low surface energy result in insufficient wettability, electrolyte absorption, and electrolyte retention, which can easily increase ion transport resistance.

[0003] To improve the electrolyte affinity of the membrane, functional modification of the membrane surface and pore walls is necessary. Electron beam irradiation grafting can form free radical active sites on the membrane surface and pore walls, causing the grafting monomers to undergo grafting reactions and introducing polar, hydrophilic, or ion-conducting groups. This improves the membrane's wettability and ion transport performance, and has advantages such as high reaction efficiency, continuous processing capability, and low initiator residue.

[0004] However, lithium battery separators are thin and highly porosimetric, making them prone to thermal shrinkage, wrinkling, pore structure deformation, or surface adhesion during electron beam irradiation due to localized temperature rises. When the separator carries the grafted monomer solution, temperature fluctuations can also affect grafting uniformity and surface quality. Furthermore, improper humidity control under low-temperature cooling conditions can easily lead to condensation on the separator or cooling support surface, affecting the stability of the irradiation grafting. Summary of the Invention

[0005] The purpose of this disclosure is to provide an apparatus for preparing an irradiated modified lithium battery separator, a method for preparing an irradiated modified lithium battery separator, and an irradiated modified lithium battery separator, thereby overcoming, to at least a certain extent, the problems of local heating, thermal shrinkage, pore structure deformation, surface adhesion, and humidity fluctuation affecting the irradiation stability of existing lithium battery separators during electron beam irradiation modification caused by limitations and defects in related technologies.

[0006] According to one aspect of this disclosure, an apparatus for preparing an irradiated modified lithium battery separator is provided, comprising an electron beam irradiation modification module, an electron beam irradiation module, a cooling module, and a controller; Electron beam irradiation modification module is used to deliver the lithium battery separator after cell impregnation to the electron beam irradiation area; An electron beam irradiation module is located above the cooling module and is used to apply electron beam irradiation to the lithium battery separator after it has passed through the carrier area of ​​the cooling module within the electron beam irradiation area, so as to obtain an irradiation-modified lithium battery separator. The cooling module is used to keep the lithium battery separator, after the individual cells are impregnated, in a state of cyclic cooling during electron beam irradiation. The controller is electrically connected to the electron beam irradiation module, the electron beam irradiation modification module, and the cooling module, respectively. It is used to control the start-up of the cooling module and maintain the cyclic cooling state, as well as control the transport of the lithium battery separator after single-cell impregnation. During the electron beam irradiation process, the controller adjusts one or more of the following parameters based on the detection signals of multiple sensors set in the electron beam irradiation modification module and the electron beam irradiation module: the transport state of the lithium battery separator after single-cell impregnation, the electron beam irradiation output parameters, and the irradiation environment parameters, so that the lithium battery separator after single-cell impregnation completes electron beam irradiation modification under the preset irradiation process conditions.

[0007] In one exemplary embodiment of this disclosure, the electron beam irradiation modification module includes an unwinding device, a winding device, a tension sensor, a temperature detector, a diaphragm temperature measuring unit, and a humidity monitor; The unwinding device is located on the film inlet side of the cooling module, and the winding device is located on the film outlet side of the cooling module. Tension sensor, used to detect the transport tension of lithium battery separator after cell impregnation; Temperature detectors are used to monitor and record in real time the temperature of the electron beam irradiation area and the temperature change of the lithium battery separator after the individual cells are impregnated during electron beam irradiation. The membrane temperature measurement unit is set along the conveying direction of the lithium battery membrane after the single cell is impregnated, and is used to detect the temperature change of the lithium battery membrane after the single cell is impregnated during the electron beam irradiation process. A humidity monitor is used to detect the humidity status within the electron beam irradiation modification module.

[0008] In one exemplary embodiment of this disclosure, the electron beam irradiation module includes an electron beam emitter, a left drying gas supply device, a right drying gas supply device, an irradiation area temperature measurement unit, and a dose detector; The electron beam emitter is positioned toward the cooling module and is used to emit an electron beam onto the surface of the lithium battery separator after the individual cells are impregnated. The left and right drying gas supply devices are respectively located on both sides of the electron beam emitter and are used to supply drying gas to the electron beam irradiation area to regulate the relative humidity of the electron beam irradiation area. The irradiation area temperature measurement unit is used to detect the temperature of the electron beam irradiation area; A dose detector is used to detect electron beam irradiation dose.

[0009] In one exemplary embodiment of this disclosure, the cooling module includes a cooling medium inlet, a cooling medium outlet, an anti-adhesion layer, a thermally conductive outer layer, a cooling channel, and a hollow roller body; Cooling channels are located on the outer periphery of the hollow roller body and are connected to the cooling medium inlet and cooling medium outlet respectively; The heat-conducting outer layer is located on the outside of the cooling channel and is used to conduct the cold energy of the cooling medium to the outer surface of the hollow roller body. An anti-adhesion layer is applied to the outer surface of the thermally conductive outer layer; The cooling medium enters the cooling channel through the cooling medium inlet, flows along the outer periphery of the hollow roller, and is discharged from the cooling medium outlet, so that the lithium battery separator after the single cell is impregnated remains in a state of circulating cooling during electron beam irradiation.

[0010] In one exemplary embodiment of this disclosure, the cooling channel extends along the axial, circumferential, or helical direction of the hollow roller body and is connected to the cooling medium inlet and the medium outlet, respectively. The cooling medium inlet and outlet are connected to the circulating cooling system via rotary joints; the cooling medium is one of the following: ethanol solution, ethylene glycol aqueous solution, propylene glycol aqueous solution, or a mixed aqueous solution of ethylene glycol and propylene glycol. The thermally conductive outer layer is made of one of the following materials: aluminum alloy, copper alloy, stainless steel, or thermally conductive ceramic material; The anti-adhesion layer is at least one of polytetrafluoroethylene coating, perfluoroalkoxy resin coating, ceramic coating, diamond-like carbon coating, or fluorocarbon coating.

[0011] According to one aspect of this disclosure, a method for preparing an irradiation-modified lithium battery separator is provided, performed using an apparatus for preparing an irradiation-modified lithium battery separator as described in any one of the above claims, the method comprising: The lithium battery separator is unwound and conveyed to the monomer impregnation area, so that the lithium battery separator is fully in contact with the grafted monomer solution to complete the monomer impregnation, so as to obtain the monomer impregnated lithium battery separator. The lithium battery separator after impregnation with individual cells is transported to the preparation device for irradiation-modified lithium battery separator. The lithium battery separator after impregnation with individual cells is continuously transported by the electron beam irradiation modification module. The cooling module is started and maintained in a cyclic cooling state by the controller. The electron beam irradiation modification module is controlled to transport the lithium battery separator after impregnation with individual cells. During the electron beam irradiation process, the transport state of the lithium battery separator after impregnation with individual cells, the electron beam irradiation output parameters, and the irradiation environment parameters are adjusted according to the detection signals of multiple sensors set in the electron beam irradiation modification module and the electron beam irradiation module. This is to coordinate and control the electron beam irradiation module, the electron beam irradiation modification module and the cooling module so that the lithium battery separator after impregnation with individual cells completes the electron beam irradiation modification under the preset irradiation process conditions. After electron beam irradiation modification is completed, the electron beam irradiation modification module is controlled by the controller to continue to transport the irradiated grafted lithium battery separator, so that it is moved out of the electron beam irradiation area, and then the post-grafting cleaning, drying and winding are performed in sequence to obtain the irradiated modified lithium battery separator.

[0012] In one exemplary embodiment of this disclosure, the lithium battery separator is one of PE separator, PP separator, and PE / PP composite separator, and the thickness of the lithium battery separator is 4μm~12μm, and the porosity is 30%~70%. The mass concentration of the grafting monomer in the grafting monomer solution is 1% to 7%; the grafting monomer is at least one of N-vinylpyrrolidone, N-vinylcaprolactam, 1-vinylimidazolium, 2-vinylpyridine, vinylphosphonic acid, allylphosphonate, diethylene glycol monovinyl ether or vinylimidazolium salt monomer.

[0013] In one exemplary embodiment of this disclosure, the impregnation temperature of the monomer is 10°C to 40°C, and the impregnation time is 60s to 300s. The surface temperature of the cooling module is -10℃ to 10℃; Electron beam irradiation output parameters include electron beam irradiation dose and electron beam energy. The electron beam irradiation dose is 5kGy~800kGy, and the electron beam energy is 30keV~5000keV. The conveying status of the lithium battery separator after single-cell impregnation includes the conveying speed, which is 0.1m / min to 30m / min.

[0014] In one exemplary embodiment of this disclosure, the irradiation environment parameters include the relative humidity of the electron beam irradiation area, which is 1% to 10%. The liquid used for post-graft cleaning is one of deionized water, ethanol, or a water-alcohol mixture, and the drying temperature is 25℃~50℃.

[0015] According to one aspect of this disclosure, an irradiation-modified lithium battery separator is provided, which is prepared according to the preparation method of the irradiation-modified lithium battery separator according to any one of the above-mentioned methods.

[0016] In the technical solution provided in this disclosure, on the one hand, by setting a cooling module in the electron beam irradiation area, the heat generated by irradiation is conducted and carried away in a timely manner through the continuous contact between the lithium battery separator after single-cell impregnation and the cooling surface, and the circulation of the cooling medium inside the module, achieving continuous cooling of the separator irradiation area; the cooling module provides stable support for the separator, keeping it flat during transportation and irradiation, and combined with the thermal conductivity and anti-adhesion effect of the cooling surface, it reduces the risk of thermal shrinkage, wrinkling, pore structure collapse, melting deformation, and surface adhesion caused by local temperature rise, thereby improving the stability of the electron beam irradiation process and the product yield of the irradiated modified separator, and improving the thermal performance of the separator. This disclosure effectively suppresses the heat accumulation generated during irradiation, prevents the mechanical properties of the separator substrate from deteriorating due to overheating, solves the common thermal damage problem in high-energy irradiation treatment, and provides a safety guarantee for improving processing efficiency. On the other hand, through the cooperation of the cooling module, the thermally conductive outer layer, and the anti-adhesion layer, the adhesion between the lithium battery separator and the roller surface is reduced while maintaining a stable temperature in the irradiation area. This reduces monomer volatilization and side reactions, promotes uniform grafting of monomers on the separator surface and the inner wall of the pores, and improves grafting efficiency and the consistency of the modification process. Furthermore, the controller can integrate electron beam irradiation output parameters expressed as energy and dose, irradiation environment parameters, and separator transport status parameters to perform multi-source signal fusion and coordinated adjustment. The controller's intelligent control overcomes the limitations of single-parameter adjustment, dynamically matching the optimal irradiation process conditions based on real-time feedback, ensuring precise and controllable grafting or crosslinking reactions, and ultimately achieving a synergistic improvement in the thermal stability and wettability of the separator.

[0017] 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 this disclosure. Attached Figure Description

[0018] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure. It is obvious that the drawings described below are merely some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0019] Figure 1 The schematic diagram illustrates the structural block diagram of the apparatus for preparing irradiated modified lithium battery separators in embodiments of this disclosure.

[0020] Figure 2 The diagram schematically illustrates the specific structure of the apparatus for preparing irradiated modified lithium battery separators in embodiments of this disclosure.

[0021] Figure 3 This is a schematic diagram of the cooling module in an embodiment of this disclosure.

[0022] Figure 4 The schematic diagram illustrates a process flow chart of the preparation method of the irradiation-modified lithium battery separator in an embodiment of this disclosure.

[0023] Figure 5 This is a schematic diagram of the irradiated modified lithium battery separator prepared in Example 1.

[0024] Figure 6 This is a schematic diagram of the irradiated modified lithium battery separator prepared in Example 1 after being kept at 135°C for 1 hour.

[0025] Figure 7 This is a schematic diagram of an irradiated modified lithium battery separator prepared in proportion.

[0026] Figure 8 This is a schematic diagram of the irradiated modified lithium battery separator prepared in the comparative example after being kept at 135°C for 1 hour.

[0027] Figure label: 100. Electron beam irradiation module; 21. Left drying gas supply device; 22. Right drying gas supply device; 82. Irradiation area temperature measurement unit; 9. Dosage detector; 200. Electron beam irradiation modification module; 51. Unwinding device; 52. Rewinding device; 3. Tension sensor; 4. Temperature detector; 81. Diaphragm temperature measurement unit; 10. Humidity monitor; 7. Cooling module; 71. Cooling medium inlet; 72. Cooling medium outlet; 73. Anti-adhesion layer; 74. Thermally conductive outer layer; 75. Cooling channel; 76. Hollow roller body. Detailed Implementation

[0028] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided to make this disclosure more comprehensive and complete, and to fully convey the concept of the example embodiments to those skilled in the art. The described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a full understanding of embodiments of this disclosure. However, those skilled in the art will recognize that the technical solutions of this disclosure can be practiced with one or more of the specific details omitted, or other methods, components, apparatus, steps, etc., can be employed. In other instances, well-known technical solutions are not shown or described in detail to avoid obscuring various aspects of this disclosure.

[0029] The terms “a,” “an,” “the,” and “the” are used in this specification to indicate the presence of one or more elements / components, etc.; the terms “including” and “having” are used to indicate an open-ended inclusion and to mean that there may be other elements / components, etc., in addition to those listed; the terms “first” and “second” are used only as markings and are not a limitation on the number of objects.

[0030] Existing irradiation modification equipment mainly focuses on electron beam emission, membrane delivery, and dosage control, but does not adequately consider continuous membrane cooling, anti-adhesion, temperature and humidity monitoring, and stable load-bearing. Therefore, it is necessary to provide a device for preparing irradiated modified lithium battery membranes that achieves stable membrane load-bearing and continuous cooling during irradiation, reduces the risks of thermal shrinkage, condensation, adhesion, and pore structure deformation, and improves the stability and performance of irradiation graft modification.

[0031] To address the aforementioned technical problems, this disclosure provides an apparatus for preparing an irradiated modified lithium battery separator. (Reference) Figure 1 As shown, the apparatus 300 for preparing the irradiated modified lithium battery separator mainly includes: an electron beam irradiation modification module 200, an electron beam irradiation module 100, a cooling module 7, and a controller 6; wherein: Electron beam irradiation modification module 200 is used to deliver the lithium battery separator after single-cell impregnation to the electron beam irradiation area; An electron beam irradiation module 100 is disposed above a cooling module 7 and is used to apply electron beam irradiation to the lithium battery separator after it has passed through the carrier area of ​​the cooling module 7 within the electron beam irradiation area, so as to obtain an irradiation-modified lithium battery separator. Cooling module 7 is used to keep the lithium battery separator after single-cell impregnation in a state of cyclic cooling during electron beam irradiation; The controller 6 is electrically connected to the electron beam irradiation module 100, the electron beam irradiation modification module 200, and the cooling module 7, respectively. It is used to control the start-up of the cooling module 7 and maintain the cyclic cooling state, as well as to control the transport of the lithium battery separator after the individual cells are impregnated. During the electron beam irradiation process, the controller 6 adjusts one or more of the following parameters based on the detection signals of multiple sensors set in the electron beam irradiation modification module 200 and the electron beam irradiation module 100: the transport state of the lithium battery separator after the individual cells are impregnated, the electron beam irradiation output parameters, and the irradiation environment parameters, so that the lithium battery separator after the individual cells are impregnated completes the electron beam irradiation modification under the preset irradiation process conditions.

[0032] Next, the apparatus for preparing the irradiation-modified lithium battery separator in the embodiments of this disclosure will be described in detail.

[0033] Electron beam irradiation modification module 200 is used to deliver the lithium battery separator after cell impregnation to the electron beam irradiation area.

[0034] In this embodiment of the disclosure, the electron beam irradiation area refers to the effective working space formed by the downward emission of an electron beam from the electron beam irradiation module. This electron beam irradiation area vertically corresponds to the upper support area of ​​the cooling module. The lithium battery separator, after being impregnated with individual cells, adheres to the upper support area of ​​the cooling module and passes through the electron beam irradiation area, thereby receiving electron beam irradiation modification within this area.

[0035] An electron beam irradiation modification module is used to transport the impregnated lithium-ion battery separator to the electron beam irradiation area and to monitor the temperature and transport tension of the impregnated lithium-ion battery separator in real time. (Reference) Figure 2 As shown, the electron beam irradiation modification module 200 includes an unwinding device 51, a winding device 52, a tension sensor 3, a temperature detector 4, a diaphragm temperature measurement unit 81, and a humidity monitor 10. The unwinding device 51 is located on the inlet side of the cooling module 7 and is used to output the lithium battery separator after impregnation with the monomers to be irradiated and modified. The winding device 52 is located on the outlet side of the cooling module 7 and is used to collect the irradiated and modified lithium battery separator. The tension sensor 3 is located on the conveying path of the impregnated lithium battery separator and is used to detect the conveying tension of the impregnated lithium battery separator and feed it back to the controller 6. The controller 6 sets the conveying tension according to the separator thickness, with thinner separators using lower conveying tension and thicker separators using higher conveying tension to ensure stable and flat conveying of the separator.

[0036] Temperature detector 4 is used to monitor the temperature of the electron beam irradiation area and the temperature change of the lithium battery separator during electron beam irradiation. Separator temperature measurement unit 81 is positioned along the transport direction of the lithium battery separator after cell impregnation and is used to detect the surface temperature of the lithium battery separator before and after entering the electron beam irradiation area. Humidity monitor 10 is used to detect the humidity status within the electron beam irradiation modification module 200.

[0037] An electron beam irradiation module 100 is disposed above a cooling module 7 and is used to apply electron beam irradiation to the lithium battery separator after it has passed through the carrier area of ​​the cooling module 7 within the electron beam irradiation area, so as to obtain an irradiation-modified lithium battery separator.

[0038] refer to Figure 2As shown, the electron beam irradiation module 100 includes an electron beam emitter 1, a left drying gas supply device 21, a right drying gas supply device 22, an irradiation area temperature measurement unit 82, and a dose detector 9. The electron beam emitter 1 is positioned facing the membrane-bearing area of ​​the cooling module 7 and is used to emit an electron beam onto the surface of the lithium-ion battery membrane after the individual cells are impregnated. The left and right drying gas supply devices 21 and 22 are respectively located on either side of the electron beam emitter 1 and are used to supply drying gas to the electron beam irradiation area to determine the relative humidity of the irradiation area, thereby reducing the humidity of the irradiation area and minimizing the risk of condensation under low-temperature cooling conditions. The irradiation area temperature measurement unit 82 is used to detect the temperature of the electron beam irradiation area in real time; the dose detector 9 is used to detect the electron beam irradiation dose and feeds the detection signal back to the controller 6.

[0039] Cooling module 7 is used to keep the lithium battery separator, after being impregnated with individual cells, in a state of cyclic cooling during electron beam irradiation.

[0040] Furthermore, such as Figure 3 As shown, in this embodiment, the cooling module 7 is a cooling support roller structure, which includes a cooling medium inlet 71, a cooling medium outlet 72, an anti-adhesion layer 73, a thermally conductive outer layer 74, a cooling channel 75, and a hollow roller body 76. The cooling channel 75 is disposed on the outer periphery of the hollow roller body 76 and is connected to the cooling medium inlet 71 and the cooling medium outlet 72 respectively; the thermally conductive outer layer 74 is disposed on the outside of the cooling channel 75 and is used to conduct the cooling energy of the cooling medium in the cooling channel 75 to the outer surface of the cooling module 7; the anti-adhesion layer 73 is disposed on the outer surface of the thermally conductive outer layer 74 and is used to reduce the adhesion of the lithium battery separator and its surface grafted monomer solution to the surface of the cooling module 7.

[0041] In actual use, the cooling medium enters the cooling channel 75 through the cooling medium inlet 71, flows along the outer periphery of the hollow roller 76, and is discharged from the cooling medium outlet 72, so that the heat-conducting outer layer 74 continuously transfers the cooling energy to the outer surface of the cooling module 7. The lithium battery separator after the single cell is impregnated is output by the unwinding device 51, and after tension adjustment, it is attached to the surface of the cooling module 7. The electron beam emitter 1 applies electron beam irradiation to the surface of the separator. During the irradiation process, the cooling module 7 continuously cools the separator, thereby reducing the local temperature rise of the separator and reducing thermal shrinkage, wrinkles, pore structure deformation, and surface adhesion.

[0042] In this embodiment of the disclosure, reference is made to Figure 3As shown, the cooling channel 75 in the cooling module extends circumferentially along the hollow roller body 76, forming an annular or arc-shaped cooling flow channel arranged along the outer periphery of the hollow roller body 76. In other embodiments, the cooling channel 75 may also extend axially or spirally along the hollow roller body 76 to increase the heat exchange area between the cooling medium and the outer periphery of the hollow roller body 76, thereby improving the heat exchange efficiency of the cooling module 7. The cooling medium inlet 71 and the cooling medium outlet 72 are respectively connected to the circulating cooling system through rotary joints, so that the cooling module 7 maintains continuous circulation of the cooling medium while rotating the conveying diaphragm.

[0043] Furthermore, in this embodiment, the cooling medium is an aqueous solution of ethylene glycol or an aqueous solution of propylene glycol; in other embodiments, an ethanol solution or a mixed aqueous solution of ethylene glycol and propylene glycol may also be used. By selecting the above-mentioned cooling medium, the cooling module 7 can maintain stable heat exchange at a lower surface temperature, avoiding the impact on the diaphragm irradiation modification process due to freezing of the cooling medium or insufficient heat exchange.

[0044] Furthermore, in this embodiment, the thermally conductive outer layer 74 is made of aluminum alloy or copper alloy to improve the heat transfer efficiency between the cooling medium in the cooling channel 75 and the outer surface of the cooling module 7; in other embodiments, the thermally conductive outer layer 74 may also be made of stainless steel or thermally conductive ceramic material. The anti-adhesion layer 73 is a polytetrafluoroethylene coating or a perfluoroalkoxy resin coating; in other embodiments, a ceramic coating, a diamond-like carbon coating, or a fluorocarbon coating may also be used. By providing the anti-adhesion layer 73, the adhesion and friction between the lithium battery separator and its surface grafted monomer solution and the surface of the cooling module 7 can be reduced, ensuring the surface integrity of the separator during continuous transport. This cooling device can achieve continuous cooling, stable load-bearing, temperature and humidity monitoring, and anti-adhesion protection during the separator's electron beam irradiation process, thereby improving the uniformity, stability, and product consistency of the separator irradiation modification.

[0045] The controller 6 is electrically connected to the electron beam irradiation module 100, the electron beam irradiation modification module 200, and the cooling module 7, respectively. It is used to control the start-up of the cooling module 7 and maintain the cyclic cooling state, as well as to control the transport of the lithium battery separator after the individual cells are impregnated. During the electron beam irradiation process, the controller 6 adjusts one or more of the following parameters based on the detection signals of multiple sensors set in the electron beam irradiation modification module 200 and the electron beam irradiation module 100: the transport state of the lithium battery separator after the individual cells are impregnated, the electron beam irradiation output parameters, and the irradiation environment parameters, so that the lithium battery separator after the individual cells are impregnated completes the electron beam irradiation modification under the preset irradiation process conditions.

[0046] The electron beam irradiation output parameters include the electron beam irradiation dose and electron beam energy, while the irradiation environment parameters include the relative humidity of the electron beam irradiation area. In this embodiment, the controller 6 can coordinately adjust the electron beam irradiation output parameters of the electron beam emitter 1, the conveying status of the unwinding device 51 and the winding device 52, the gas supply status of the left drying gas supply device 21 and the right drying gas supply device 22, and the cooling status of the cooling module 7 based on the detection signals from the tension sensor 3, the temperature detector 4, the diaphragm temperature measuring unit 81, the irradiation area temperature measuring unit 82, the dose detector 9, and the humidity monitor 10. This ensures that the lithium battery separator after single-cell impregnation completes electron beam irradiation modification under the preset irradiation process conditions represented by a stable temperature and dry environment. The controller adjusts the electron beam irradiation dose, beam intensity, and / or beam energy, controls the conveying speed and start / stop status of the lithium battery separator after single-cell impregnation, and controls the cooling module 7 to be in a circulating cooling state by adjusting the flow rate and / or temperature of the cooling medium, thereby achieving coordinated control of the irradiation, conveying, and cooling processes. Adjust the flow rate and / or temperature of the cooling medium to make the surface temperature of the cooling module -10℃ to 10℃.

[0047] For example, the transport state of the lithium battery separator after impregnation is adjusted according to the detection signal of the tension sensor 3, and the electron beam irradiation output parameters of the electron beam irradiation module 100 and the separator transport speed of the electron beam irradiation modification module 200 are coordinated and adjusted according to the detection signal of the dose detector 9, so that the lithium battery separator after impregnation reaches the preset electron beam irradiation dose; the electron beam irradiation dose can be 5kGy~800kGy. The controller adaptively adjusts the electron beam irradiation output parameters and / or the separator transport speed according to the detection signals of the separator temperature measuring unit 81 and the irradiation area temperature measuring unit 82, suppresses heat accumulation during the irradiation process, and continuously dissipates heat through the cooling module 7; the controller regulates the dryness of the irradiation environment according to the detection signal of the humidity monitor 10, so that the lithium battery separator after impregnation continuously and stably completes electron beam irradiation modification under the preset irradiation process conditions. The preset irradiation process conditions include: preset transport tension, surface temperature, relative humidity, and irradiation conditions. The preset conveying tension ensures that the lithium battery separator, after being impregnated with individual cells, remains flat and is not torn during the pulling process. The surface temperature of the cooling module is -10℃ to 10℃, and the relative humidity is 1% to 10%. Irradiation conditions are expressed by electron beam irradiation dose and electron beam energy, with electron beam irradiation dose ranging from 5kGy to 800kGy and electron beam energy ranging from 30keV to 5000keV.

[0048] In actual use, the lithium battery separator after being impregnated with individual cells is unwound by the unwinding device 51, and the conveying tension is adjusted by the tension sensor 3. It then adheres to the surface of the cooling module 7 and enters the electron beam irradiation area. The electron beam emitter 1 irradiates the impregnated lithium battery separator, while the cooling medium circulates within the cooling channel 75 and transfers cooling energy to the outer surface of the cooling module 7 through the thermally conductive outer layer 74, ensuring stable cooling of the impregnated lithium battery separator during electron beam irradiation. The left and right drying gas supply devices 21 and 22 continuously supply drying gas to the electron beam irradiation area, and the humidity monitor 10 monitors the humidity of the irradiation area in real time to achieve the required relative humidity, preventing condensation on the separator surface or the cooling module 7 surface under low-temperature conditions.

[0049] It should be noted that, in this embodiment, the cooling module 7 combines continuous heat exchange, stable load-bearing, and anti-adhesion functions through the cooperation of the cooling channel 75, the thermally conductive outer layer 74, and the anti-adhesion layer 73. The cooperation of the irradiation area temperature measurement unit 82, the diaphragm temperature measurement unit 81, the humidity monitor 10, and the dose detector 9 enables real-time monitoring and control of the irradiation area temperature, diaphragm surface temperature, ambient humidity, and irradiation dose. This reduces the risks of thermal shrinkage, wrinkling, pore structure deformation, surface adhesion, and condensation in the lithium battery diaphragm after single-cell impregnation during electron beam irradiation, improving the stability of the irradiation modification process and product consistency.

[0050] In this embodiment, a cooling module is provided in the electron beam irradiation area. Through continuous contact between the diaphragm and the cooling surface, and the circulation of the cooling medium inside the module, the heat generated by irradiation is conducted and carried away in a timely manner, achieving continuous cooling of the irradiation area of ​​the diaphragm. At the same time, the cooling module provides stable support for the diaphragm, keeping it flat during transportation and irradiation. Combined with the thermal conductivity and anti-adhesion effect of the cooling surface, the risks of thermal shrinkage, wrinkling, pore structure collapse, melting deformation, and surface adhesion caused by local temperature rise are reduced, thereby improving the stability of the electron beam irradiation process and the product yield of the irradiated modified diaphragm.

[0051] In this embodiment, the combination of a cooling module, a thermally conductive outer layer, and an anti-adhesion layer reduces adhesion between the separator and the roller surface while maintaining a stable temperature in the irradiation area. This reduces monomer volatilization and side reactions, promotes uniform grafting of the grafted monomers on the separator surface and pore walls, and improves grafting efficiency and modification consistency. A drying gas supply device, an irradiation area temperature measurement unit, a humidity monitor, a tension sensor, and a dose detector are used to monitor and control the temperature, humidity, separator tension, and irradiation dose in the irradiation area in real time, reducing the risk of condensation under low-temperature cooling conditions and ensuring stable operation of the electron beam irradiation, separator transport, and cooling processes. Combining monomer impregnation, cooling irradiation grafting, post-grafting cleaning, drying, and winding, this method is suitable for various lithium battery separators made of PE, PP, and PE / PP composites, as well as different grafted monomer systems. It can improve the electrolyte wettability, liquid retention capacity, mechanical properties, and ion transport performance of the separator, making it suitable for continuous irradiation modification production of ultra-thin lithium battery separators.

[0052] Based on the above-described apparatus for preparing irradiated modified lithium battery separators, this disclosure also provides a method for preparing irradiated modified lithium battery separators using the aforementioned apparatus, as described above. Figure 4 As shown, the preparation method of this irradiation-modified lithium battery separator mainly includes the following steps: Step S410: Unwind the lithium battery separator and transport it to the monomer impregnation area so that the lithium battery separator can fully contact the grafted monomer solution to complete the monomer impregnation, so as to obtain the monomer impregnated lithium battery separator. Step S420: The lithium battery separator after impregnation of individual cells is transported to the preparation device for irradiation-modified lithium battery separator. The lithium battery separator after impregnation of individual cells is continuously transported through the electron beam irradiation modification module. The cooling module is started and maintained in a cyclic cooling state by the controller. The electron beam irradiation modification module is controlled to transport the lithium battery separator after impregnation of individual cells. During the electron beam irradiation process, one or more of the following parameters are adjusted according to the detection signals of multiple sensors set in the electron beam irradiation modification module and the electron beam irradiation module: the transport state of the lithium battery separator after impregnation of individual cells, the electron beam irradiation output parameters, and the irradiation environment parameters. This is to coordinate and control the electron beam irradiation module, the electron beam irradiation modification module, and the cooling module so that the lithium battery separator after impregnation of individual cells completes electron beam irradiation modification under the preset irradiation process conditions. In step S430, after electron beam irradiation modification is completed, the electron beam irradiation modification module is controlled by the controller to continue to transport the irradiated grafted lithium battery separator, so that it is moved out of the electron beam irradiation area, and then the post-grafting cleaning, drying and winding are performed in sequence to obtain the irradiated modified lithium battery separator.

[0053] Next, the preparation method of the irradiation-modified lithium battery separator will be explained in detail.

[0054] Step S410: Unwind the lithium battery separator and transport it to the monomer impregnation area so that the lithium battery separator can fully contact the grafted monomer solution and complete the monomer impregnation to obtain the monomer-impregnated lithium battery separator.

[0055] In this step, the lithium battery separator is unwound by the unwinding device, guided by guide rollers and kept stable before entering the monomer impregnation area. This allows the lithium battery separator to fully contact the grafted monomer solution, enabling the monomer to be grafted onto the surface and inner pore walls of the lithium battery separator, thus completing the monomer impregnation process and obtaining a monomer-impregnated lithium battery separator. The lithium battery separator is one of PE, PP, or PE / PP composite separators, with a thickness of 4μm to 12μm and a porosity of 30% to 70%. The aforementioned lithium battery separator exhibits good chemical stability, electrolyte resistance, and a porous structure, making it suitable for electron beam irradiation grafting modification. Using an ultra-thin base film helps reduce ion transport resistance and meets the requirements of high-energy-density batteries. Controlling the appropriate pore structure helps to balance electrolyte adsorption capacity, ion transport performance, and separator mechanical strength.

[0056] The mass concentration of the grafting monomer in the grafting monomer solution is 1%–7%; the grafting monomer is one or more of N-vinylpyrrolidone, N-vinylcaprolactam, 1-vinylimidazolium, 2-vinylpyridine, vinylphosphonic acid, allyl phosphonate, diethylene glycol monovinyl ether, or vinylimidazolium salt monomer. All of the above grafting monomers contain unsaturated groups that can participate in the irradiation grafting reaction, enabling grafting polymerization to occur at active sites formed by electron beam irradiation. Among these, lactam, imidazole, pyridine, phosphonate, ether oxide, silane, and ionic groups can improve the surface polarity and electrolyte affinity of the polymer membrane, which is beneficial for improving the membrane's wettability, liquid retention capacity, and ion transport performance. Controlling the grafting monomer concentration within an appropriate range is beneficial for balancing grafting efficiency, pore structure preservation, and membrane mechanical stability.

[0057] The impregnation temperature for monomers is 10℃~40℃, and the impregnation time is 60s~300s. Appropriate impregnation temperature and time can ensure that the grafted monomers fully penetrate the membrane surface and pores.

[0058] In step S420, the lithium battery separator after impregnation of individual cells is transported to the preparation device for irradiation-modified lithium battery separator. The lithium battery separator after impregnation of individual cells is continuously transported through the electron beam irradiation modification module. The cooling module is started and maintained in a cyclic cooling state by the controller. The electron beam irradiation modification module is controlled to transport the lithium battery separator after impregnation of individual cells. During the electron beam irradiation process, one or more of the following parameters are adjusted according to the detection signals of multiple sensors set in the electron beam irradiation modification module and the electron beam irradiation module: the transport state of the lithium battery separator after impregnation of individual cells, the electron beam irradiation output parameters, and the irradiation environment parameters. This is to coordinate and control the electron beam irradiation module, the electron beam irradiation modification module, and the cooling module so that the lithium battery separator after impregnation of individual cells completes electron beam irradiation modification under the preset irradiation process conditions.

[0059] In this embodiment, the obtained monomer-impregnated lithium battery separator is transported to an apparatus for preparing irradiated modified lithium battery separators. The surface temperature of the cooling module is -10°C to 10°C. During electron beam irradiation of the monomer-impregnated lithium battery separator via the electron beam irradiation module, the electron beam irradiation dose is 5 kGy to 800 kGy, the electron beam energy is 30 keV to 5000 keV, and the transport speed of the monomer-impregnated lithium battery separator is 0.1 m / min to 30 m / min. The lower surface temperature of the cooling module can suppress irradiation heating and reduce the risk of separator thermal shrinkage and pore structure deformation. Reasonable control of irradiation dose, electron beam energy, and transport speed can maintain the mechanical properties and continuous processing stability of the separator while ensuring the grafting effect. The above process parameters are beneficial for balancing monomer impregnation effect, irradiation grafting efficiency, and separator structural stability.

[0060] The left and right drying gas supply devices are respectively located on both sides of the electron beam emitter to supply drying gas to the electron beam irradiation area, maintaining the relative humidity of the irradiation area at 1%~10%. Introducing drying gas into the device for electron beam irradiation of modified lithium battery separators and controlling the relative humidity of the irradiation area helps reduce the risk of condensation on the separator surface and cooling support surface under low-temperature cooling conditions, ensuring the stable progress of the irradiation grafting reaction.

[0061] In step S430, after electron beam irradiation modification is completed, the electron beam irradiation modification module is controlled by the controller to continue to transport the irradiated grafted lithium battery separator, so that it is moved out of the electron beam irradiation area, and then the post-grafting cleaning, drying and winding are performed in sequence to obtain the irradiated modified lithium battery separator.

[0062] Irradiation-grafted lithium-ion battery separators refer to lithium-ion battery separators impregnated with monomers treated by electron beam irradiation, i.e., irradiation-modified lithium-ion battery separators. The liquid used for post-grafting cleaning is one of deionized water, ethanol, or a water-alcohol mixture, with a drying temperature of 25℃~50℃. Post-grafting cleaning uses deionized water, ethanol, or a water-alcohol mixture; the water-alcohol mixture can be a deionized water / ethanol mixture. Using deionized water, ethanol, or a water-alcohol mixture for cleaning is beneficial for removing unreacted monomers and residues; controlling the drying temperature within an appropriate range can reduce the risk of separator thermal shrinkage and pore structure deformation while removing residual solvents.

[0063] Furthermore, the preparation method of the irradiation-modified lithium battery separator of this disclosure will be specifically described in conjunction with the embodiments.

[0064] Example 1

[0065] A PE membrane with a thickness of 4μm and a porosity of 30% was selected as the lithium battery separator, i.e., the base membrane. The grafted monomer, represented by N-vinylpyrrolidone, was added to an ethanol / water mixed solvent to prepare a grafted monomer solution with a mass concentration of 1%. The PE membrane was unwound from the unwinding device. After tension adjustment and position correction, the membrane conveying tension was stabilized at the preset conveying tension, and kept flat along the set conveying path without significant deviation before entering the monomer impregnation area. The preset conveying tension can be any suitable value, as long as it ensures that the film remains flat and does not break during the pulling process. After entering the monomer impregnation area, impregnation was completed at 10℃ for 60 seconds to fully wet the surface and pore walls of the PE membrane with the grafted monomer solution. The monomer-impregnated PE separator was transported to a cooling device to adhere to the surface of the cooling module. The surface temperature of the cooling module was controlled at -10°C. Dry gas was introduced into the electron beam irradiation area to maintain a relative humidity of 1%. Electron beam irradiation was performed using an electron beam irradiation module with an irradiation dose of 5 kGy and an electron beam energy of 30 keV. The transport speed of the monomer-impregnated lithium battery separator was 0.1 m / min. After irradiation, the electron beam irradiation modification module was controlled by a controller to continue transporting the irradiated grafted lithium battery separator out of the electron beam irradiation area. The separator was cleaned with a deionized water / ethanol mixture, dried at 25°C, and then wound up to obtain the irradiated grafted modified PE separator, which is the irradiated modified lithium battery separator. The irradiated grafted modified PE separator prepared in Example 1 is as follows: Figure 5 As shown.

[0066] The irradiated grafted modified PE membrane prepared in Example 1 had a smooth surface, without any transparency, wrinkles, melt spots, or significant thermal shrinkage. Tests showed that the unmodified PE membrane had an electrolyte contact angle of 78.4°, a liquid absorption rate of 106.2%, an ionic conductivity of 0.45 mS / cm, a longitudinal tensile strength of 142.5 MPa, a transverse tensile strength of 134.5 MPa, and a puncture strength of 381 gf. After being kept at 135°C for 1 hour, the longitudinal thermal shrinkage was 13.5%, and the transverse thermal shrinkage was 12.4%. The irradiated grafted modified PE membrane had an electrolyte contact angle of 33.8°, a liquid absorption rate of 124.5%, an ionic conductivity of 0.94 mS / cm, a longitudinal tensile strength of 158.6 MPa, a transverse tensile strength of 144.7 MPa, and a puncture strength of 423 gf. A schematic diagram of the irradiated grafted modified PE membrane prepared in Example 1 being kept at 135°C for 1 hour is shown below. Figure 6 As shown in the figure. Tests show that after being kept at 135℃ for 1 hour, the longitudinal shrinkage is 2.5% and the transverse shrinkage is 1.4%.

[0067] Example 2

[0068] A PP membrane with a thickness of 6 μm and a porosity of 45% was selected as the lithium battery separator, i.e., the base membrane. Grafted monomers, represented by 1-vinylimidazole, were added to an ethanol / water mixed solvent to prepare a grafted monomer solution with a mass concentration of 3%. The PP membrane was unwound by an unwinding device. After tension adjustment and position correction, the membrane conveying tension was stabilized at the preset conveying tension, ensuring it remained flat along the set conveying path without significant deviation, before entering the monomer impregnation area. The preset conveying tension can be any suitable value, as long as it ensures the film remains flat and does not break during the pulling process. After entering the monomer impregnation area, the membrane was impregnated at 20°C for 120 seconds to complete the monomer impregnation, allowing the monomer solution to fully wet the surface and inner pore walls of the PP membrane. The monomer-impregnated PP membrane was then conveyed to the surface of the cooling module, and the surface temperature of the cooling module was controlled at -2°C. Dry gas was introduced into the electron beam irradiation area to maintain a relative humidity of 3%. Electron beam irradiation was performed using an electron beam irradiation module with an irradiation dose of 100 kGy and an electron beam energy of 600 keV. The transport speed of the lithium battery separator after single-cell impregnation was 3 m / min. After irradiation, the electron beam irradiation modification module was controlled by a controller to continue transporting the irradiated grafted lithium battery separator out of the electron beam irradiation area. The separator was then sequentially cleaned with a water-alcohol mixture, dried at 35°C, and wound up to obtain the irradiated grafted modified PP separator, which is the irradiated modified lithium battery separator.

[0069] The resulting irradiated grafted modified PP separator had a smooth surface, without any transparency, wrinkles, melt spots, or significant thermal shrinkage. Tests showed that the unmodified PP separator had an electrolyte contact angle of 75.3°, a liquid absorption rate of 103.5%, an ionic conductivity of 0.41 mS / cm, a longitudinal tensile strength of 148.3 MPa, a transverse tensile strength of 136.4 MPa, a puncture strength of 401 gf, and a longitudinal thermal shrinkage of 9.4% and a transverse thermal shrinkage of 7.6% after being held at 135°C for 1 hour. The irradiated grafted modified PP separator in this embodiment had an electrolyte contact angle of 34.6°, a liquid absorption rate of 134.5%, an ionic conductivity of 0.88 mS / cm, a longitudinal tensile strength of 152.4 MPa, a transverse tensile strength of 146.3 MPa, a puncture strength of 445 gf, and a longitudinal thermal shrinkage of 1.8% and a transverse thermal shrinkage of 1.7% after being held at 135°C for 1 hour.

[0070] Example 3

[0071] A PE / PP composite membrane with a thickness of 8 μm and a porosity of 60% was selected as the lithium battery separator, i.e., the base membrane. The grafted monomer, represented by N-vinylcaprolactam, was added to an ethanol / water mixed solvent to prepare a grafted monomer solution with a mass concentration of 5%. The PE / PP composite membrane was unwound, tension adjusted, and position corrected to stabilize the membrane conveying tension at the preset conveying tension, ensuring it remained flat along the set conveying path without significant deviation, before entering the monomer impregnation area. The preset conveying tension can be any suitable value, as long as the film remains flat and does not break during the pulling process. After entering the monomer impregnation area, it was impregnated at 30°C for 200 seconds to complete the monomer impregnation, allowing the grafted monomer solution to fully penetrate the pore structure of the composite separator. The impregnated composite separator was conveyed to a cooling device to adhere to the surface of the cooling module. The surface temperature of the cooling module was controlled at 5°C, and the relative humidity of the electron beam irradiation area was 5%. Electron beam irradiation was performed using an electron beam irradiation module with an irradiation dose of 500 kGy and an electron beam energy of 1500 keV. The conveying speed of the impregnated lithium battery separator was 10 m / min. After irradiation, the separator was cleaned with a deionized water / ethanol mixture and dried at 40°C to obtain the irradiated grafted modified PE / PP composite separator. This irradiated grafted modified PE / PP composite separator is the irradiated modified lithium battery separator.

[0072] The resulting irradiated grafted modified PE / PP composite membrane had a smooth surface, without any transparency, wrinkles, melt spots, or significant thermal shrinkage. Tests showed that the unmodified PP membrane had an electrolyte contact angle of 76.4°, a liquid absorption rate of 106.2%, an ionic conductivity of 0.42 mS / cm, a longitudinal tensile strength of 142.6 MPa, a transverse tensile strength of 131.2 MPa, a puncture strength of 431 gf, and a longitudinal thermal shrinkage of 10.3% and a transverse thermal shrinkage of 8.7% after being kept at 135℃ for 1 hour. The irradiated grafted modified PE / PP composite membrane obtained in Example 3 has an electrolyte contact angle of 37.6°, a liquid absorption rate of 128.5%, an ionic conductivity of 0.85 mS / cm, a longitudinal tensile strength of 156.4 MPa, a transverse tensile strength of 141.8 MPa, a puncture strength of 467 gf, and a longitudinal heat shrinkage of 1.5% and a transverse heat shrinkage of 1.3% after being kept at 135°C for 1 hour.

[0073] Example 4

[0074] A PE membrane with a thickness of 12 μm and a porosity of 70% was selected as the lithium battery separator, i.e., the base membrane. Grafted monomers, represented by diethylene glycol monovinyl ether, were added to an ethanol solvent to prepare a grafted monomer solution with a mass concentration of 7%. The PE membrane was unwound, tension adjusted, and position corrected to stabilize the membrane conveying tension at a preset tension, ensuring it remained flat along the set conveying path without significant deviation, before entering the monomer impregnation area. The preset conveying tension could be any suitable value, as long as it ensured the film remained flat and did not break during the pulling process. After entering the monomer impregnation area, the membrane was impregnated at 40°C for 300 seconds to complete the monomer impregnation, ensuring the grafted monomer solution was evenly distributed on the membrane surface and the inner walls of the pores. The impregnated PE membrane was then conveyed to the surface of a cooling module, where the surface temperature was controlled at 10°C. Dry gas was introduced into the electron beam irradiation area to maintain a relative humidity of 10%. Electron beam irradiation was performed using an electron beam irradiation module. The electron beam irradiation dose was 800 kGy, and the electron beam energy was 5000 keV. The transport speed of the lithium battery separator after single-cell impregnation was 30 m / min. After irradiation, the electron beam irradiation modification module was controlled by a controller to continue transporting the irradiated grafted lithium battery separator out of the electron beam irradiation area. The separator was then cleaned with ethanol and dried at 50°C to obtain the irradiated grafted modified PE separator. This irradiated grafted modified PE separator is the irradiated modified lithium battery separator.

[0075] The irradiated grafted modified PE membrane obtained in Example 4 had a smooth surface and did not exhibit transparency, wrinkles, melt spots, or significant thermal shrinkage. Tests showed that the unmodified PE membrane had an electrolyte contact angle of 79.4°, a liquid absorption rate of 107.6%, an ionic conductivity of 0.46 mS / cm, a longitudinal tensile strength of 145.6 MPa, a transverse tensile strength of 133.2 MPa, a puncture strength of 392 gf, and a longitudinal thermal shrinkage of 14.2% and a transverse thermal shrinkage of 12.7% after being kept at 135°C for 1 hour. In Example 4, the irradiated grafted modified PE membrane had an electrolyte contact angle of 35.6°, a liquid absorption rate of 131.5%, an ionic conductivity of 0.84 mS / cm, a longitudinal tensile strength of 158.1 MPa, a transverse tensile strength of 143.9 MPa, a puncture strength of 437 gf, and a longitudinal heat shrinkage of 4.5% and a transverse heat shrinkage of 3.3% after being kept at 135°C for 1 hour.

[0076] Comparative Example

[0077] The comparative example differs from Example 1 in that the cooling module is not activated during electron beam irradiation, while the remaining monomer impregnation, irradiation dose, electron beam energy, delivery speed, cleaning, and drying conditions remain consistent. The modified diaphragm provided in the comparative example without the irradiation-modified cooling device is as follows: Figure 7 As shown in the image. Reference Figure 7 a and Figure 7 As can be seen from b in the figure, the PE diaphragm obtained in the comparative example shows local areas of transparency, slight wrinkles and dimensional shrinkage, and some areas have traces of uneven grafting.

[0078] The PE membrane obtained in the comparative example showed an electrolyte contact angle of 46.4°, a liquid absorption rate of 116.2%, an ionic conductivity of 0.45 mS / cm, a longitudinal tensile strength of 144.6 MPa, a transverse tensile strength of 133.2 MPa, and a puncture strength of 381 gf. After being kept at 135℃ for 1 hour, the longitudinal heat shrinkage was 10.3%, and the transverse heat shrinkage was 9.7%. A schematic diagram of the modified membrane provided in the comparative example without the irradiated modification and cooling device being kept at 135℃ for 1 hour is shown below. Figure 8 As shown in the image.

[0079] As can be seen from the comparison, the technical solutions of Examples 1-4 solve the problems of local transparency, slight wrinkles and size shrinkage in the diaphragm.

[0080] This disclosure also provides an irradiated modified lithium battery separator prepared according to steps S410 to S430, which can be applied to lithium batteries. The irradiated modified lithium battery separator prepared in this disclosure improves the electrolyte affinity of the separator.

[0081] Furthermore, the above figures are merely illustrative of the processes included in the method according to exemplary embodiments of this disclosure and are not intended to be limiting. It is readily understood that the processes shown in the above figures do not indicate or limit the temporal order of these processes. Additionally, it is readily understood that these processes may be executed synchronously or asynchronously, for example, in multiple modules.

[0082] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the appended claims.

[0083] It should be understood that this disclosure is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this disclosure is limited only by the appended claims.

Claims

1. An apparatus for preparing an irradiated modified lithium battery separator, characterized in that, It includes an electron beam irradiation modification module, an electron beam irradiation module, a cooling module, and a controller; The electron beam irradiation modification module is used to deliver the lithium battery separator after single-cell impregnation to the electron beam irradiation area. The electron beam irradiation module is disposed above the cooling module and is used to apply electron beam irradiation to the lithium battery separator after it has passed through the carrier area of ​​the cooling module within the electron beam irradiation area, so as to obtain an irradiation-modified lithium battery separator. The cooling module is used to keep the lithium battery separator after the single cell is impregnated in a cyclic cooling state during electron beam irradiation. The controller is electrically connected to the electron beam irradiation module, the electron beam irradiation modification module, and the cooling module, respectively. It is used to control the start-up of the cooling module and maintain the cyclic cooling state, as well as control the transport of the lithium battery separator after single-cell impregnation. During the electron beam irradiation process, the controller adjusts one or more of the following parameters based on the detection signals of multiple sensors installed in the electron beam irradiation modification module and the electron beam irradiation module: the transport state of the lithium battery separator after single-cell impregnation, the electron beam irradiation output parameters, and the irradiation environment parameters, so that the lithium battery separator after single-cell impregnation completes electron beam irradiation modification under preset irradiation process conditions.

2. The apparatus for preparing irradiated modified lithium battery separator according to claim 1, characterized in that, The electron beam irradiation modification module includes an unwinding device, a winding device, a tension sensor, a temperature detector, a diaphragm temperature measurement unit, and a humidity monitor. The unwinding device is located on the film inlet side of the cooling module, and the winding device is located on the film outlet side of the cooling module. The tension sensor is used to detect the transport tension of the lithium battery separator after the monomer is impregnated. The temperature detector is used to monitor and record in real time the temperature of the electron beam irradiation area and the temperature change of the lithium battery separator after the single cell is impregnated during the electron beam irradiation process; The membrane temperature measuring unit is arranged along the conveying direction of the lithium battery membrane after the monomer is impregnated, and is used to detect the temperature change of the lithium battery membrane after the monomer is impregnated during the electron beam irradiation process. The humidity monitor is used to detect the humidity status within the electron beam irradiation modification module.

3. The apparatus for preparing irradiated modified lithium battery separator according to claim 1, characterized in that, The electron beam irradiation module includes an electron beam emitter, a left drying gas supply device, a right drying gas supply device, an irradiation area temperature measurement unit, and a dose detector. The electron beam emitter is positioned toward the cooling module and is used to emit an electron beam toward the surface of the lithium battery separator after the individual cells are impregnated. The left and right drying gas supply devices are respectively located on both sides of the electron beam emitter and are used to supply drying gas to the electron beam irradiation area to adjust the relative humidity of the electron beam irradiation area. The irradiation area temperature measurement unit is used to detect the temperature of the electron beam irradiation area; The dose detector is used to detect the electron beam irradiation dose.

4. The apparatus for preparing irradiated modified lithium battery separator according to claim 1, characterized in that, The cooling module includes a cooling medium inlet, a cooling medium outlet, an anti-adhesion layer, a heat-conducting outer layer, a cooling channel, and a hollow roller body; The cooling channel is located on the outer periphery of the hollow roller body and is connected to the cooling medium inlet and the cooling medium outlet, respectively. The thermally conductive outer layer is disposed on the outside of the cooling channel and is used to conduct the cooling capacity of the cooling medium to the outer surface of the hollow roller body. The anti-adhesion layer is disposed on the outer surface of the thermally conductive outer layer; The cooling medium enters the cooling channel through the cooling medium inlet, flows along the outer periphery of the hollow roller body, and is discharged from the cooling medium outlet, so that the lithium battery separator after the single cell is impregnated remains in a state of circulating cooling during electron beam irradiation.

5. The apparatus for preparing irradiated modified lithium battery separator according to claim 4, characterized in that, The cooling channel extends along the axial, circumferential, or helical direction of the hollow roller body and is connected to the cooling medium inlet and the cooling medium outlet, respectively. The cooling medium inlet and the cooling medium outlet are connected to the circulating cooling system via rotary joints; the cooling medium is one of ethanol solution, ethylene glycol aqueous solution, propylene glycol aqueous solution, or a mixed aqueous solution of ethylene glycol and propylene glycol; The thermally conductive outer layer is made of one of aluminum alloy, copper alloy, stainless steel or thermally conductive ceramic material; The anti-adhesion layer is at least one of polytetrafluoroethylene coating, perfluoroalkoxy resin coating, ceramic coating, diamond-like carbon coating, or fluorocarbon coating.

6. A method for preparing an irradiated modified lithium battery separator, characterized in that, The method is performed using the apparatus for preparing irradiated modified lithium battery separators as described in any one of claims 1-5, and includes: The lithium battery separator is unwound and conveyed to the monomer impregnation area, so that the lithium battery separator is fully in contact with the grafted monomer solution to complete the monomer impregnation, so as to obtain the monomer impregnated lithium battery separator. The lithium-ion battery separator after impregnation with monomers is transported to the preparation device for irradiation-modified lithium-ion battery separator. The lithium-ion battery separator after impregnation with monomers is continuously transported by the electron beam irradiation modification module. The cooling module is started and maintained in a cyclic cooling state by the controller. The electron beam irradiation modification module is controlled to transport the lithium-ion battery separator after impregnation with monomers. During the electron beam irradiation process, the transport state of the lithium-ion battery separator after impregnation with monomers, the electron beam irradiation output parameters, and the irradiation environment parameters are adjusted according to the detection signals of multiple sensors set in the electron beam irradiation modification module and the electron beam irradiation module. This is to coordinate and control the electron beam irradiation module, the electron beam irradiation modification module and the cooling module so that the lithium-ion battery separator after impregnation with monomers completes electron beam irradiation modification under the preset irradiation process conditions. After electron beam irradiation modification is completed, the electron beam irradiation modification module is controlled by the controller to continue to transport the irradiated grafted lithium battery separator, so that it is moved out of the electron beam irradiation area, and then the post-grafting cleaning, drying and winding are performed in sequence to obtain the irradiated modified lithium battery separator.

7. The method for preparing the irradiated modified lithium battery separator according to claim 6, characterized in that, The lithium battery separator is one of PE separator, PP separator, or PE / PP composite separator, and the thickness of the lithium battery separator is 4μm~12μm, and the porosity is 30%~70%. The mass concentration of the grafting monomer in the grafting monomer solution is 1% to 7%; the grafting monomer is at least one of N-vinylpyrrolidone, N-vinylcaprolactam, 1-vinylimidazolium, 2-vinylpyridine, vinylphosphonic acid, allylphosphonate, diethylene glycol monovinyl ether, or vinylimidazolium salt monomer.

8. The method for preparing the irradiated modified lithium battery separator according to claim 6, characterized in that, The impregnation temperature of the monomer is 10℃~40℃, and the impregnation time is 60s~300s; The surface temperature of the cooling module is -10℃ to 10℃; The electron beam irradiation output parameters include electron beam irradiation dose and electron beam energy, wherein the electron beam irradiation dose is 5kGy~800kGy and the electron beam energy is 30keV~5000keV; The conveying state of the lithium battery separator after impregnation of the monomer includes the conveying speed, which is 0.1m / min to 30m / min.

9. The method for preparing the irradiated modified lithium battery separator according to claim 6, characterized in that, The irradiation environment parameters include the relative humidity of the electron beam irradiation area, which is 1% to 10%. The liquid used for post-graft cleaning is one of deionized water, ethanol, or a water-alcohol mixture, and the drying temperature is 25℃~50℃.

10. An irradiation-modified lithium battery separator, characterized in that, The irradiated modified lithium battery separator is prepared by the method for preparing the irradiated modified lithium battery separator according to any one of claims 6-9.

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