Membrane preparation method and device, dry-method battery and preparation method and device of dry-method battery

Abstract

The invention provides a diaphragm preparation method and device, a dry-method battery and a preparation method and device of the dry-method battery. The diaphragm preparation method comprises the following steps: preparing a positive electrode diaphragm and a negative electrode diaphragm containing a polytetrafluoroethylene binder; and carrying out irradiation treatment on the positive electrode membrane and the negative electrode membrane to passivate the surfaces of the polytetrafluoroethylene fibers. According to the preparation method of the diaphragm, side reactions can be reduced, and the first effect of a dry-method battery is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy batteries, and in particular to a membrane preparation method and device, a dry-process battery, and a preparation method and device thereof. Background Art

[0002] As the global energy transition accelerates, battery technology, as its core driving force, is undergoing unprecedented changes. Among many emerging battery technologies, dry electrode technology stands out with its unique advantages and becomes a key breakthrough point for reducing production costs and improving battery performance. The use of dry electrode technology to prepare dry batteries is one of the most advanced technologies for secondary batteries. Dry electrode technology is a revolutionary battery manufacturing process that completely abandons the use of solvents in the traditional wet electrode manufacturing process.

[0003] The core of dry electrode technology is that its preparation process completely avoids the use of solvents. Specifically, the technology first mixes the electrode active material (such as lithium iron phosphate or graphite), the conductive agent (such as carbon black) and the binder (such as polytetrafluoroethylene PTFE) in a dry state. The mixed material does not form a solution but remains solid. Next, these solid materials are compacted into a membrane through high-intensity mechanical pressure, such as calendering or hot pressing, to form the electrode layer of the battery. This process can not only effectively combine the materials tightly, but also control the microstructure of the electrode material, further optimizing the battery performance.

[0004] Dry electrode technology has demonstrated significant comprehensive advantages in the field of battery manufacturing. Its core lies in mixing and compacting electrode materials through physical means rather than solvents. This innovative method not only greatly reduces the cost of the battery production process, including avoiding the cost of solvent recovery and treatment, reducing energy consumption, but also significantly improves energy efficiency because there is no need to go through the solvent evaporation step in the wet process, thereby speeding up production and improving overall production efficiency.

[0005] At the same time, the environmental friendliness of dry technology cannot be ignored. It significantly reduces solvent emissions and reduces environmental pollution, which is in line with the development trend of global green production. In terms of material performance, dry electrode technology can more accurately control the microstructure of electrode materials, thereby optimizing conductivity and mechanical strength, reducing side reactions inside the battery, and effectively improving the cycle life and energy density of the battery, opening up a new path for breakthroughs in battery performance. In addition, the safety risks brought about by the use of solvents in the wet process have been effectively alleviated in the dry process, making the production environment safer.

[0006] More importantly, dry electrode technology has a wide range of applications. It is not only suitable for existing lithium-ion battery systems, but can also be expanded to emerging technology fields such as solid-state batteries and sodium-ion batteries, demonstrating its strong technical compatibility and future potential, and providing strong support for the sustainable development and technological innovation of the battery manufacturing industry.

[0007] Although dry electrode technology has shown advantages in many aspects, it still has certain limitations in practical applications, especially in the initial efficiency of batteries. Summary of the invention

[0008] The main purpose of the present invention is to provide a membrane preparation method and device, a dry-process battery and a preparation method and device thereof, which can reduce the occurrence of side reactions and improve the initial efficiency of the dry-process battery.

[0009] In order to achieve the above object, according to one aspect of the present invention, a method for preparing a membrane is provided, comprising:

[0010] preparing a positive electrode membrane and a negative electrode membrane containing a polytetrafluoroethylene binder;

[0011] The positive electrode membrane and the negative electrode membrane are irradiated to passivate the surface of the polytetrafluoroethylene fiber.

[0012] Furthermore, the diaphragm preparation method also includes:

[0013] The positive electrode membrane and the negative electrode membrane after the surface of the polytetrafluoroethylene fiber is passivated are rolled up.

[0014] Furthermore, the irradiation energy for irradiating the positive electrode membrane and the negative electrode membrane is gamma rays, electron beams, X-rays or ultraviolet rays.

[0015] Furthermore, the step of irradiating the positive electrode membrane and the negative electrode membrane to passivate the surface of the polytetrafluoroethylene fiber includes:

[0016] Using gamma rays to scan the front and back sides of the positive electrode membrane at the same time or separately scan the front and back sides of the positive electrode membrane;

[0017] Gamma rays are used to scan the front and back sides of the negative electrode membrane at the same time or separately.

[0018] Furthermore, the relationship between the irradiation amount y and the time x of the irradiation treatment of gamma rays satisfies y=4 / 3x.

[0019] Furthermore, the irradiation amount of the gamma ray irradiation treatment ranges from 10 kGy to 50 kGy, and the time is from 1 hour to 4 hours.

[0020] Furthermore, the surface passivation depth of the polytetrafluoroethylene fiber is 1 nm to 10 nm.

[0021] According to another aspect of the present invention, there is provided a membrane preparation device, which is applied to the above-mentioned membrane preparation method, comprising:

[0022] Dry membrane production line, used for preparing positive and negative electrode membranes, wherein the positive and negative electrode membranes contain polytetrafluoroethylene as a binder;

[0023] The irradiation device is arranged downstream of the dry-process membrane production line and is used to irradiate the positive electrode membrane and the negative electrode membrane to passivate the surface of the polytetrafluoroethylene fiber.

[0024] Furthermore, the membrane preparation device also includes a winding device, which is arranged downstream of the irradiation device and is used to wind up the positive electrode membrane and the negative electrode membrane after irradiation by the irradiation device.

[0025] Furthermore, the irradiation device includes an irradiation box and at least two gamma-ray generators arranged in the irradiation box, the positive electrode diaphragm and the negative electrode diaphragm pass through the irradiation box, and the positive electrode diaphragm and the negative electrode diaphragm are located between the at least two gamma-ray generators.

[0026] According to another aspect of the present invention, a method for preparing a dry-process battery is provided, wherein the positive electrode membrane and the negative electrode membrane prepared by the above-mentioned membrane preparation method are used, and the method for preparing the dry-process battery comprises:

[0027] Laminating the positive electrode film and the positive electrode current collector to obtain a positive electrode sheet;

[0028] Laminating the negative electrode film and the negative electrode current collector to obtain a negative electrode sheet;

[0029] Cutting the positive electrode sheet and the negative electrode sheet;

[0030] The cut positive electrode sheet, negative electrode sheet and separator are stacked to prepare a soft pack battery;

[0031] The electrolyte is injected into the soft-pack battery and the components are divided into different capacities to obtain a dry-process battery.

[0032] According to another aspect of the present invention, there is provided a dry-process battery manufacturing device, comprising the above-mentioned membrane manufacturing device, and further comprising:

[0033] A thermal laminating machine is used to laminate the positive electrode film after irradiation with the positive electrode current collector to obtain a positive electrode sheet, and to laminate the negative electrode film after irradiation with the negative electrode current collector to obtain a negative electrode sheet;

[0034] A cutting device, used for cutting the positive electrode sheet and the negative electrode sheet;

[0035] A laminating device is used to laminate the cut positive electrode sheets, negative electrode sheets and separators to form a soft-pack battery;

[0036] The formation and capacity separation device is used for forming and separating soft-pack batteries.

[0037] According to another aspect of the present invention, a dry-process battery is provided, which is prepared by using the above-mentioned method for preparing a dry-process battery.

[0038] The technical solution of the present invention is applied, and the diaphragm preparation method includes: preparing a positive electrode diaphragm and a negative electrode diaphragm containing a polytetrafluoroethylene binder; irradiating the positive electrode diaphragm and the negative electrode diaphragm to passivate the surface of the polytetrafluoroethylene fiber. The battery diaphragm prepared by the diaphragm preparation method can significantly reduce the side reaction between lithium ions and PTFE during the formation process, avoid the absorption of lithium ions at inactive sites, and thus improve the initial charge and discharge efficiency of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0040] Figure 1 is a flow chart of a method for preparing a membrane according to an embodiment of the present invention; and

[0041] Figure 2 It is a schematic structural diagram of a membrane preparation device according to an embodiment of the present invention.

[0042] The above drawings include the following reference numerals:

[0043] 1. Dry film production line; 2. Irradiation device; 21. Irradiation box; 22. Gamma ray generator; 3. Winding device. DETAILED DESCRIPTION

[0044] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0045] In the related art, when dry-process batteries use polytetrafluoroethylene (PTFE) as a binder, the side reaction problem between PTFE and lithium ions during the battery formation stage becomes a key bottleneck restricting its performance and large-scale production. As a high-performance binder, PTFE can effectively combine components such as electrode active materials and conductive agents, but in the battery charge and discharge cycle, especially in the first cycle, the chemical properties of PTFE may cause irreversible chemical reactions with lithium ions. These side reactions not only consume precious lithium resources, but also lead to a decrease in the first efficiency (first effect) of the battery, affecting the overall performance and service life of the battery. In addition, the side reaction of PTFE with lithium ions may also aggravate the instability inside the electrode, affect the safety and reliability of the battery, and thus hinder the further promotion and application of dry-process battery technology.

[0046] In order to solve the above problems, refer to Figure 1 As shown, according to an embodiment of the present invention, the diaphragm preparation method includes: preparing a positive electrode diaphragm and a negative electrode diaphragm containing a polytetrafluoroethylene binder; irradiating the positive electrode diaphragm and the negative electrode diaphragm to passivate the surface of the polytetrafluoroethylene fiber.

[0047] Passivation of the PTFE fiber surface can significantly reduce the side reactions between lithium ions and PTFE during the formation process, avoid the absorption of lithium ions at inactive sites, and thus improve the initial charge and discharge efficiency of the battery. The first efficiency of dry-process batteries treated with gamma rays is generally higher than that of untreated batteries, reaching a maximum of 89.95%, while the first efficiency of untreated batteries is around 86.82%, an increase of 3.6%. As we all know, the higher the first efficiency of the battery, the more difficult it is to improve the first efficiency of the battery. This application adopts a method of passivating the surface of the PTFE fiber, so that the first efficiency of the battery is improved by more than 3%. In terms of the improvement ratio of the first efficiency of the battery, it is already a substantial improvement, so it also has a substantial improvement in the performance of the battery.

[0048] During the formation process, the side reaction between lithium ions and PTFE will lead to energy loss and battery performance degradation. By irradiating PTFE, the chemical activity of the PTFE fiber surface is reduced, the side reactions during the formation are reduced, and the energy utilization rate and cycle stability of the battery are improved. The passivation of the PTFE fiber surface can improve the stability of the electrochemical environment inside the battery, reduce the risk of internal short circuits, and thus improve the safety of the battery. At the same time, reducing the occurrence of side reactions also helps to extend the cycle life of the battery because the internal losses of the battery during the charge and discharge process are reduced.

[0049] Compared with traditional wet electrode manufacturing, dry battery technology itself has the advantages of low production cost, no solvent use, and environmentally friendly preparation process. As an optimization step for dry battery preparation, PTFE irradiation treatment can significantly improve battery performance and indirectly optimize production costs. In particular, in large-scale production, high-efficiency and high-initial-efficiency batteries can reduce overall costs.

[0050] In general, gamma-ray irradiation of positive and negative electrode membranes containing PTFE can effectively improve the initial efficiency of dry-process batteries, reduce side reactions, and improve safety and cycle life. This is an important innovation based on dry-process battery technology and is of great significance for promoting the commercial application of dry-process battery technology. In addition, the introduction of this treatment method also provides a new optimization path for dry-process battery preparation technology, which helps to further improve the overall performance of the battery.

[0051] In one embodiment, the membrane preparation method further includes: rolling up the positive electrode membrane and the negative electrode membrane after the surface of the polytetrafluoroethylene fiber is passivated.

[0052] It is a necessary step in the battery manufacturing process to roll up the positive and negative electrode membranes after the irradiation treatment by the irradiation device and the surface of the polytetrafluoroethylene (PTFE) fiber is passivated. The rolled membranes are convenient for storage, transportation and subsequent battery assembly.

[0053] When the positive electrode membrane and the negative electrode membrane are directly produced without the need for subsequent storage and transportation, after the positive electrode membrane and the negative electrode membrane of the battery are completed, the positive electrode membrane and the negative electrode membrane can be directly irradiated, and then directly processed to achieve the preparation of the positive electrode sheet and the negative electrode sheet.

[0054] In one embodiment, the radiation energy for irradiating the positive electrode membrane and the negative electrode membrane is gamma rays, electron beams, X-rays or ultraviolet rays.

[0055] Gamma rays have high penetration and energy, and can penetrate deep into the material for treatment. Gamma ray irradiation of the membrane can effectively passivate the surface of polytetrafluoroethylene (PTFE) fibers, reduce side reactions with lithium ions, and improve the initial efficiency of the battery. At the same time, gamma ray treatment can reach the entire thickness of the membrane to ensure the consistency of the treatment effect. Gamma ray treatment is suitable for scenarios where it is necessary to modify the material deeply, especially for processing thicker membranes or situations where high penetration irradiation is required.

[0056] Electron beam irradiation can concentrate energy to treat the surface of the membrane, and has a significant effect on the surface modification of the material. Compared with gamma rays, the penetration depth of electron beams is limited, which is more suitable for treating thinner membranes. The irradiation depth can be precisely controlled to reduce the impact on the internal structure of the membrane. Electron beam irradiation treatment is suitable for thin membranes or when there are special requirements for surface treatment. Due to the relatively low operating and maintenance costs of electron beam equipment and high operational flexibility, it has certain cost advantages in large-scale production.

[0057] The penetration ability of X-rays is between that of gamma rays and electron beams, and can modify the membrane to a certain extent, while also having a certain effect on the surface. X-ray treatment can balance the modification effects on the surface and the interior of the membrane, and is suitable for membranes that require both surface and internal modification. X-ray treatment is suitable for situations where medium-depth modification of the membrane is required, especially when the membrane thickness is moderate, and can achieve better treatment results.

[0058] Ultraviolet radiation mainly affects the surface of the membrane and can promote surface reactions and modifications. Ultraviolet treatment is usually used for surface cleaning, disinfection, or the breaking and reorganization of chemical bonds to improve the surface properties of the membrane, such as increasing surface activity or changing the surface molecular structure, but has little effect on the inside of the membrane. Ultraviolet radiation treatment is suitable for situations where the surface of the membrane needs to be modified but it is not necessary to penetrate into the material. Ultraviolet equipment is relatively simple and has low operating costs, making it suitable for production links with high surface treatment requirements.

[0059] Different types of irradiation energy can optimize the different characteristics of polytetrafluoroethylene fibers, improve the overall performance of the membrane, and are suitable for a variety of battery types, such as lithium-ion batteries, sodium-ion batteries, etc. Gamma rays and electron beams can penetrate deep into the material and treat the fibers more thoroughly, which is suitable for the preparation of high-energy density batteries; X-rays and ultraviolet rays can produce more subtle chemical changes on the surface, which is suitable for precision equipment with special requirements for battery performance and can significantly improve the stability and reliability of the battery.

[0060] In one embodiment, the step of irradiating the positive electrode diaphragm and the negative electrode diaphragm to passivate the surface of the polytetrafluoroethylene fiber includes: using gamma rays to scan the front and back surfaces of the positive electrode diaphragm simultaneously or separately; using gamma rays to scan the front and back surfaces of the negative electrode diaphragm simultaneously or separately.

[0061] The main purpose of irradiating the positive and negative surfaces of the positive and negative diaphragms with gamma rays is to passivate the surface of the polytetrafluoroethylene (PTFE) fiber. The passivation of the PTFE fiber surface can reduce the side reaction between lithium ions and PTFE during the first charge and discharge (formation) of the battery, which means that more lithium ions can participate in the charge and discharge process of the active material, thereby improving the first charge and discharge efficiency of the battery. By reducing the side reaction between PTFE and lithium ions, the loss of inactive lithium inside the battery can be reduced, and the continuous thickening of the SEI film (solid electrolyte interface film) can be reduced, thereby extending the cycle life of the battery. PTFE is a commonly used binder, but under certain conditions, it may react with other components inside the battery to produce gas or thermal runaway risks. Gamma ray irradiation treatment can reduce the possibility of such reactions and improve the overall safety of the battery by changing the surface properties of the PTFE fiber. Irradiating the front and back of the diaphragm simultaneously or separately can ensure the uniformity of the surface modification of the PTFE fiber, thereby improving the consistency of the electrochemical performance of the battery, which is of great significance for battery quality control in mass production.

[0062] Scanning the front and back of the membrane separately provides process flexibility. If the materials or structures of the front and back of the membrane are different, the irradiation parameters can be adjusted to achieve the best treatment effect for each side, which is especially important when processing complex membrane structures.

[0063] In one embodiment, the relationship between the irradiation amount y and the time x of the irradiation treatment of gamma rays satisfies y=4 / 3x.

[0064] By limiting the relationship between the irradiation dose and the irradiation time, the irradiation time of the gamma ray can be precisely controlled according to the desired surface passivation depth, thereby controlling the irradiation dose, thereby ensuring the consistency and repeatability of the surface modification of the PTFE fiber.

[0065] By precisely controlling the time x, damage or structural change of the PTFE fiber caused by excessive γ-ray irradiation can be avoided, thereby protecting the electrochemical properties of the membrane.

[0066] By formulating the relationship between irradiation dose and irradiation time, the control of process parameters in the production process is simplified, allowing operators to more intuitively understand the relationship between time and dose, and facilitate rapid adjustment and optimization of processing conditions to meet different production needs.

[0067] In one embodiment, the irradiation amount of the gamma ray irradiation treatment ranges from 10 kGy to 50 kGy, and the duration ranges from 1 hour to 4 hours.

[0068] The irradiation treatment of gamma rays has a passivation effect on the surface of polytetrafluoroethylene (PTFE) fibers. The irradiation dose and treatment time are key parameters, and the relationship between them has a significant effect on the passivation of PTFE fibers. The amount of irradiation directly affects the degree of surface modification of PTFE fibers. Within a certain range, with the increase of irradiation (10kGy to 50kGy), more chemical bonds on the surface of PTFE fibers are broken, and the surface active sites are reduced, thereby achieving a deeper passivation effect. The effect of treatment time (1h to 4h) on the effect is mainly achieved by controlling the duration of contact between gamma rays and the surface of PTFE fibers. The increase in time means that PTFE fibers are exposed to gamma rays for a longer time, which can theoretically enhance the modification effect, but after a certain period of time, the effect of improving the first effect will gradually tend to saturation, and the occupancy and operating costs of the equipment may also increase.

[0069] The high energy of gamma rays can break the CF bonds on the surface of PTFE fibers, resulting in the generation of more free radicals and other chemically active species on the surface. Through subsequent chemical reactions, these active sites can be passivated to form a more stable surface structure and reduce side reactions with lithium ions. In addition to changes in the chemical structure, gamma ray irradiation may also cause slight changes in the physical properties of PTFE fibers, such as adjustments in surface roughness, which helps to improve the adhesion and stability of the diaphragm. Within the appropriate range of irradiation (10kGy to 50kGy) and treatment time (1h to 4h), passivation of the PTFE fiber surface can effectively reduce side reactions during the formation (first charge and discharge) process and improve the first charge and discharge efficiency of the battery.

[0070] The irradiation amount and time selection within this range can balance the passivation effect of PTFE fiber and the overall performance of the membrane, avoiding the destruction of fiber structure caused by excessive irradiation or insufficient passivation due to too short treatment. The setting of treatment time is directly related to production efficiency. The time range of 1h to 4h ensures sufficient gamma ray contact time and avoids equipment idleness and increased energy consumption caused by too long treatment, thereby improving battery performance while optimizing production costs.

[0071] The gamma ray irradiation dose range specified in the claims is 10kGy to 50kGy, and the time range is 1h to 4h, which is based on the precise match between the properties of PTFE fibers and the requirements for improving battery performance. This specific selection of irradiation parameters is intended to improve the initial efficiency and energy density of dry-process batteries through efficient and controllable surface modification, while ensuring the economy and efficiency of the production process.

[0072] In one embodiment, the surface passivation depth of the polytetrafluoroethylene fiber is 1 nm to 10 nm.

[0073] The passivation depth of polytetrafluoroethylene (PTFE) fiber surface after γ-ray irradiation treatment is 1nm to 10nm. The selection of this parameter range has a significant impact on battery performance.

[0074] Passivation of the PTFE fiber surface can effectively reduce the side reactions between lithium ions and PTFE fibers, thereby reducing the energy loss of the battery during the formation process. The passivation depth of 1nm to 10nm just covers the surface active layer of the PTFE fiber, which can effectively prevent the absorption of lithium ions in this layer and improve the initial efficiency of the battery. Surface passivation within the range of 1nm to 10nm can ensure that the integrity of the internal structure of the PTFE fiber is not affected. Too deep passivation may destroy the microstructure inside the fiber, thereby affecting the electrochemical performance and cycle stability of the battery, and shallow passivation is not enough to completely prevent side reactions.

[0075] The passivation layer on the surface of PTFE fiber can serve as a protective film to reduce the mechanical wear of electrode materials during the charging and discharging process, enhance the stability of the electrode, and thus extend the cycle life of the battery. Modification of the surface of PTFE fiber can also improve its compatibility with the electrolyte, reduce electrolyte decomposition, and further enhance the performance and safety of the battery. The passivation depth of 1nm to 10nm is directly related to the amount and time of γ-ray irradiation. Treatment within this range can control the operating cost and production efficiency of the equipment while ensuring the improvement of battery performance, and avoid waste of resources caused by excessive treatment.

[0076] Limiting the surface passivation depth of PTFE fibers to 1nm to 10nm is a balance between ensuring improved battery performance and protecting the integrity of the fiber's internal structure. This depth selection not only reduces the side reactions between PTFE fibers and lithium ions, but also maintains the physical and chemical stability of the fibers, which plays an important role in improving the efficiency and service life of dry-process batteries.

[0077] See also Figure 2 As shown, in one embodiment, according to an embodiment of the present invention, a diaphragm preparation device is applied to the above-mentioned diaphragm preparation method, including: a dry diaphragm production line 1, used to prepare positive electrode diaphragms and negative electrode diaphragms, wherein the positive electrode diaphragms and the negative electrode diaphragms contain polytetrafluoroethylene as a binder; an irradiation device 2, arranged downstream of the dry diaphragm production line 1, used to irradiate the positive electrode diaphragms and the negative electrode diaphragms to passivate the surface of the polytetrafluoroethylene fiber.

[0078] The positive electrode diaphragm and negative electrode diaphragm prepared by the dry diaphragm production line 1 contain polytetrafluoroethylene (PTFE) as a binder. After being irradiated by the downstream irradiation device 2, the surface of the PTFE fiber is passivated. This process can significantly reduce the side reaction between PTFE and lithium ions, thereby improving the initial efficiency of the battery, reducing energy loss, and increasing the overall energy density and cycle life of the battery. Integrating the dry diaphragm production line 1 with the irradiation device 2 realizes a continuous production process from diaphragm preparation to surface modification, improves production efficiency, reduces intermediate processing links, and reduces battery production costs. This integrated process also ensures the consistency and repeatability of diaphragm processing, which is conducive to the stability of battery performance.

[0079] The irradiation device 2 can accurately control the irradiation amount and time of gamma rays to ensure that the passivation depth of the PTFE fiber surface is in the range of 1nm to 10nm, which not only avoids the destruction of the fiber structure caused by excessive treatment, but also ensures sufficient passivation of the surface active sites, thereby achieving the best battery performance improvement effect.

[0080] The dry-process membrane preparation process does not use solvents, which reduces the risk of fire and explosion compared to the wet process. The passivation of the PTFE fiber surface further improves the safety of the battery, reduces the thermal runaway phenomenon that may occur during the battery's charge and discharge process, and enhances the reliability of the battery. The integrated membrane preparation device design takes into account the needs of large-scale production. Through automated control and continuous production, it reduces the error rate of manual operations, improves manufacturing efficiency, and facilitates the commercialization of dry-process battery technology.

[0081] The diaphragm preparation device integrates the dry diaphragm production line and the irradiation device to achieve efficient, continuous and precise processing of positive and negative electrode diaphragms containing PTFE, effectively improving the initial efficiency and overall performance of the battery, while reducing production costs, improving production safety and reliability, and providing strong support for the industrial application of dry battery technology.

[0082] In one embodiment, the membrane preparation device further includes a winding device 3 , which is disposed downstream of the irradiation device 2 and is used to wind up the positive electrode membrane and the negative electrode membrane after irradiation by the irradiation device 2 .

[0083] It is a necessary step in the battery manufacturing process to roll up the positive and negative electrode membranes after the irradiation treatment by the irradiation device and the surface of the polytetrafluoroethylene (PTFE) fiber is passivated. The rolled membranes are convenient for storage, transportation and subsequent battery assembly.

[0084] In one embodiment, the irradiation device 2 includes an irradiation box 21 and at least two γ-ray generators 22 arranged in the irradiation box 21 , the positive electrode diaphragm and the negative electrode diaphragm pass through the irradiation box 21 , and the positive electrode diaphragm and the negative electrode diaphragm are located between the at least two γ-ray generators 22 .

[0085] The layout of at least two gamma-ray generators 22 can ensure that the positive electrode diaphragm and the negative electrode diaphragm are irradiated with gamma rays from multiple directions when passing through the irradiation box 21, thereby achieving uniform irradiation of the front and back surfaces of the diaphragms. This uniformity is crucial for the passivation of the PTFE fiber surface, which can avoid local over-treatment or under-treatment and ensure the consistency of the overall performance of the diaphragm.

[0086] When the diaphragm passes between multiple gamma-ray generators, it can be irradiated by multiple sources at the same time, significantly improving processing efficiency and production speed. By adjusting the number, position and output power of the gamma-ray generators, the passivation depth of the PTFE fiber surface can be precisely controlled to ensure that it is within the optimal range of 1nm to 10nm.

[0087] The design of the irradiation box 21 can effectively isolate gamma rays, reduce the radiation risk to the surrounding environment and operators, and improve the safety of the production process. At the same time, the closed design of the box also protects the diaphragm from external contamination and maintains the purity of the diaphragm.

[0088] According to an embodiment of the present invention, a preparation method of a dry-process battery adopts a positive electrode membrane and a negative electrode membrane prepared by the above-mentioned membrane preparation method, and the preparation method of the dry-process battery includes: laminating a positive electrode membrane and a positive electrode collector to obtain a positive electrode sheet; laminating a negative electrode membrane and a negative electrode collector to obtain a negative electrode sheet; cutting the positive electrode sheet and the negative electrode sheet; stacking the cut positive electrode sheet, the negative electrode sheet and the separator to prepare a soft-pack battery; injecting electrolyte into the soft-pack battery, and performing volume separation to obtain a dry-process battery.

[0089] The dry-process battery obtained by the above preparation method uses radiation energy to passivate the surface of the positive and negative electrode membranes containing PTFE, effectively reducing the side reactions between PTFE fibers and lithium ions, thereby greatly improving the initial efficiency of the battery. This enables the dry-process battery to more efficiently utilize lithium ions during the first charge and discharge, thereby improving the overall energy output of the battery.

[0090] The passivation of the PTFE fiber surface reduces the decomposition of the membrane during the charge and discharge cycle and reduces the continuous thickening of the SEI film, thereby extending the cycle life of the dry-process battery, which means that the battery can still maintain a high performance after multiple uses, improving its reliability and economy in practical applications. The radiation energy treatment of PTFE fibers not only improves the initial efficiency of the battery, but also enhances the safety of the battery. Since the side reaction between lithium ions and PTFE is reduced during the formation process, the risk of thermal runaway inside the battery is reduced, improving the overall safety.

[0091] According to an embodiment of the present invention, a preparation device for a dry-process battery includes the above-mentioned membrane preparation device, and also includes: a hot laminating machine, which is used to laminate the positive electrode membrane after irradiation with the positive electrode collector to obtain a positive electrode sheet, and laminate the negative electrode membrane after irradiation with the negative electrode collector to obtain a negative electrode sheet; a cutting device, which is used to cut the positive electrode sheet and the negative electrode sheet; a stacking device, which is used to stack the cut positive electrode sheet, negative electrode sheet and separator to form a soft-pack battery; a formation and capacity separation device, which is used to perform formation and capacity separation on the soft-pack battery.

[0092] By using the above-mentioned dry-process battery preparation device, the positive electrode membrane and the negative electrode membrane after PTFE fiber passivation can be used to prepare dry-process batteries, thereby effectively reducing the side reaction between PTFE fibers and lithium ions and greatly improving the initial efficiency of the battery.

[0093] According to an embodiment of the present invention, a dry-process battery is prepared by using the above-mentioned method for preparing a dry-process battery.

[0094] Since gamma rays are used to passivate the surface of the PTFE fibers in the positive and negative electrode membranes, the efficiency of the battery during the first charge and discharge is significantly improved. This is attributed to the effective passivation of the active sites on the surface of the PTFE fibers, which reduces the loss of lithium ions in side reactions, thereby improving the battery's first charge and discharge efficiency, i.e., the first efficiency.

[0095] The passivation treatment of the diaphragm PTFE fiber reduces the side reactions between the battery and the electrolyte during the charge and discharge process, slows down the thickening rate of the SEI film, and thus significantly extends the cycle life of the battery. The membrane optimization and gamma-ray treatment in the dry battery preparation method help to improve the utilization rate of the battery's active materials and reduce the proportion of inactive components, thereby increasing the energy density while keeping the battery volume unchanged. The dry battery preparation method eliminates the use of solvents in the wet process, reduces the steps of solvent recovery and treatment, and reduces production costs. At the same time, the automated and continuous production process improves production efficiency and further reduces the manufacturing cost per unit battery. Batteries prepared by the dry method reduce the risk of fire and explosion due to the reduced use of solvents. The passivation treatment of the PTFE fiber surface also reduces the possibility of thermal runaway inside the battery and improves battery safety.

[0096] The dry-process battery prepared according to the embodiment of the present invention significantly improves the first efficiency, energy density and cycle life of the battery through unique membrane preparation and surface treatment technology, reduces production costs, and enhances the safety and environmental protection of the battery.

[0097] Embodiment 1:

[0098] Material preparation: lithium iron phosphate positive electrode material, graphite negative electrode material, sulfide electrolyte, fibrous material, positive electrode current collector, negative electrode current collector, battery insulating film, battery aluminum-plastic film, etc.

[0099] Equipment preparation: automated production line for dry-process membranes, automated production line for bare cell preparation, automated production line for cell assembly and chemical composition;

[0100] (1) preparing a positive electrode film by rolling a positive electrode main material of lithium iron phosphate 97% (can be 95%-97%), PTFE 1% (can be 1.5%-2.5%), SP 2% (can be 1.5%-2.5%) through a dry film automated production line method; irradiating the front and back surfaces simultaneously using a gamma-ray generator before rolling;

[0101] (2) preparing a negative electrode membrane by rolling a negative electrode main material of graphite negative electrode 97% (can be 95%-97%), PTFE 1% (can be 1.5%-2.5%), SP 2% (can be 1.5%-2.5%) through a dry film automated production line method; irradiating the front and back surfaces simultaneously using a gamma-ray generator before rolling;

[0102] (3) Laminating the positive electrode film and the positive electrode current collector by a thermal laminating machine to obtain a positive electrode sheet;

[0103] (4) Laminating the negative electrode film and the negative electrode current collector by a thermal laminating machine to obtain a negative electrode sheet;

[0104] (5) Cutting the positive electrode sheet and the negative electrode sheet;

[0105] (6) Laminating the cut electrode sheets and separators to prepare a soft-pack battery;

[0106] (7) injecting No. 1 electrolyte to carry out chemical formation;

[0107] (8) After chemical composition, the dry-process battery RLT01 is obtained.

[0108] Comparative Example 1:

[0109] Material preparation: lithium iron phosphate positive electrode material, graphite negative electrode material, sulfide electrolyte, fibrous material, positive electrode current collector, negative electrode current collector, battery insulating film, battery aluminum-plastic film, etc.

[0110] Equipment preparation: automated production line for dry-process membranes, automated production line for bare cell preparation, automated production line for cell assembly and chemical composition;

[0111] (1) preparing a positive electrode membrane by rolling a positive electrode main material of lithium iron phosphate 97% (can be 95%-97%), PTFE 1% (can be 1.5%-2.5%), and SP 2% (can be 1.5%-2.5%) through a dry membrane automated production line method;

[0112] (2) preparing a negative electrode membrane by rolling a negative electrode main material of graphite negative electrode 97% (can be 95%-97%), PTFE 1% (can be 1.5%-2.5%), and SP 2% (can be 1.5%-2.5%) through a dry membrane automated production line method;

[0113] (3) Laminating the positive electrode film and the positive electrode current collector by a thermal laminating machine to obtain a positive electrode sheet;

[0114] (4) Laminating the negative electrode film and the negative electrode current collector by a thermal laminating machine to obtain a negative electrode sheet;

[0115] (5) Cutting the positive electrode sheet and the negative electrode sheet;

[0116] (6) Laminating the cut electrode sheets and separators to prepare a soft-pack battery;

[0117] (7) injecting No. 1 electrolyte to carry out chemical formation;

[0118] (8) After chemical composition, the dry-process battery RLT02 is obtained.

[0119] Table 1 Comparison of dry-process batteries obtained in Example 1 and Comparative Example 1

[0120]

[0121] It can be seen from Table 1 that the dry-process battery finally obtained after irradiating the membrane by the membrane preparation method of the present invention has obvious improvements in formation charging, divided capacity charging, divided capacity discharge point and first efficiency compared to the dry-process battery finally obtained after the membrane is not irradiated. After the positive electrode membrane and the negative electrode membrane are prepared by the membrane preparation method of the present invention, the first efficiency of the dry-process battery finally obtained is improved by more than 3%, so that the first efficiency of the battery is significantly improved.

[0122] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0123] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein.

[0124] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a membrane, characterized in that: include: preparing a positive electrode membrane and a negative electrode membrane containing a polytetrafluoroethylene binder; The positive electrode membrane and the negative electrode membrane are irradiated to passivate the surface of the polytetrafluoroethylene fiber.

2. The method for preparing a membrane according to claim 1, characterized in that: The diaphragm preparation method also includes: The positive electrode membrane and the negative electrode membrane after the surface of the polytetrafluoroethylene fiber is passivated are rolled up.

3. The method for preparing a membrane according to claim 1, characterized in that: The irradiation energy for irradiating the positive electrode membrane and the negative electrode membrane is gamma rays, electron beams, X-rays or ultraviolet rays.

4. The method for preparing a membrane according to claim 3, characterized in that: The steps of irradiating the positive electrode membrane and the negative electrode membrane to passivate the surface of the polytetrafluoroethylene fiber include: Using gamma rays to scan the front and back sides of the positive electrode membrane at the same time or separately scan the front and back sides of the positive electrode membrane; Gamma rays are used to scan the front and back sides of the negative electrode membrane at the same time or separately.

5. The method for preparing a membrane according to claim 4, characterized in that: The relationship between the irradiation amount y and the time x of the irradiation treatment of gamma rays satisfies y=4 / 3x.

6. The method for preparing a membrane according to claim 4, characterized in that: The surface passivation depth of the polytetrafluoroethylene fiber is 1 nm to 10 nm; and / or the irradiation amount of the gamma ray irradiation treatment ranges from 10 kGy to 50 kGy, and the time is 1 hour to 4 hours.

7. A membrane preparation device, applied to the membrane preparation method according to any one of claims 1 to 6, characterized in that: include: A dry film production line (1) for preparing positive electrode films and negative electrode films, wherein the positive electrode films and the negative electrode films contain polytetrafluoroethylene as a binder; The irradiation device (2) is arranged downstream of the dry-process membrane production line (1) and is used to irradiate the positive electrode membrane and the negative electrode membrane to passivate the surface of the polytetrafluoroethylene fiber.

8. The membrane preparation device according to claim 7, characterized in that: The membrane preparation device also includes a winding device (3), which is arranged downstream of the irradiation device (2) and is used to wind up the positive electrode membrane and the negative electrode membrane after irradiation by the irradiation device (2).

9. The membrane preparation device according to claim 7, characterized in that: The irradiation device (2) comprises an irradiation box (21) and at least two gamma-ray generators (22) arranged in the irradiation box (21), the positive electrode diaphragm and the negative electrode diaphragm pass through the irradiation box (21), and the positive electrode diaphragm and the negative electrode diaphragm are located between the at least two gamma-ray generators (22).

10. A method for preparing a dry-process battery, characterized in that: The positive electrode membrane and the negative electrode membrane are prepared by the membrane preparation method according to any one of claims 1 to 6, and the preparation method of the dry-process battery comprises: Laminating the positive electrode film and the positive electrode current collector to obtain a positive electrode sheet; Laminating the negative electrode film and the negative electrode current collector to obtain a negative electrode sheet; Cutting the positive electrode sheet and the negative electrode sheet; The cut positive electrode sheet, negative electrode sheet and separator are stacked to prepare a soft pack battery; The electrolyte is injected into the soft-pack battery and the components are divided into different capacities to obtain a dry-process battery.

11. A dry-cell battery manufacturing device, characterized in that: The membrane preparation device according to any one of claims 7 to 9, further comprising: A thermal laminating machine is used to laminate the positive electrode film after irradiation with the positive electrode current collector to obtain a positive electrode sheet, and to laminate the negative electrode film after irradiation with the negative electrode current collector to obtain a negative electrode sheet; A cutting device, used for cutting the positive electrode sheet and the negative electrode sheet; A laminating device is used to laminate the cut positive electrode sheets, negative electrode sheets and separators to form a soft-pack battery; The formation and capacity separation device is used for forming and separating soft-pack batteries.

12. A dry-process battery, characterized in that: The dry-cell battery is prepared by the preparation method of claim 10.

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