Polymer isolation plate and preparation method thereof, test battery and test device

Abstract

The invention provides a polymer isolation plate and a preparation method thereof, a test battery and a test device, and belongs to the technical field of batteries, the test battery comprises the polymer isolation plate, a positive electrode, a negative electrode and an electrolyte; a first limiting groove and a second limiting groove are formed in two back-to-back surfaces of the polymer isolation plate, and the first limiting groove and the second limiting groove are communicated through a hole channel; the positive electrode and the negative electrode are respectively arranged in the first limiting groove and the second limiting groove; and the electrolyte is injected into the hole channel. According to the test battery, the positive electrode and the negative electrode can be arranged on the two sides of the hole channel in an attached mode, a cavity is eliminated, and the convection inhibition effect of electrolyte is effectively improved; and the hole channels are also beneficial to absorbing the electrolyte and enhancing retention of the electrolyte, and the hole wall friction resistance of the hole channels also effectively limits flowing of the electrolyte, so that the effect of inhibiting convection is achieved. Therefore, the problem that a symmetrical electrode device is large in test error can be solved.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a polymer separator and its preparation method, a test battery and a test device. Background Technology

[0002] In the testing and evaluation of electrode materials, reversibility, ion / electron transport kinetics, and electrolyte stability, symmetrical electrode devices are a classic testing structure. Traditional symmetrical electrode devices employ a separating membrane or plate between the positive and negative electrodes to confine the electrodes and suppress electrolyte convection.

[0003] Conventional symmetrical electrode devices suffer from large testing errors due to structural design and assembly issues. Summary of the Invention

[0004] In view of the above problems, this application proposes a polymer separator plate and its preparation method, a test battery and a test device, aiming to solve the problem of large test errors in symmetrical electrode devices.

[0005] In a first aspect, this application provides a test battery, comprising: a polymer separator, a positive electrode, a negative electrode, and an electrolyte; the polymer separator has a first limiting groove and a second limiting groove on two opposite surfaces, the first limiting groove and the second limiting groove being connected through a hole channel; the positive electrode and the negative electrode are respectively disposed in the first limiting groove and the second limiting groove; the electrolyte is injected into the hole channel.

[0006] In the technical solution of this application, the test battery allows the positive and negative electrodes to be fitted together on both sides of the pore channel, eliminating the presence of cavities and effectively improving the convection suppression effect of the electrolyte. The pore channel also facilitates electrolyte absorption and enhances electrolyte retention, while the frictional resistance of the pore wall effectively restricts electrolyte flow, thus suppressing convection. Furthermore, the overall structure of the test battery in this application is simple, not involving the assembly of multiple components, which can reduce testing errors caused by assembly accuracy issues. Therefore, this application can solve the problem of large testing errors inherent in symmetrical electrode devices.

[0007] In some embodiments, the aperture channel includes a plurality of holes, at least a portion of which are interconnected.

[0008] In the technical solution of this application, the pore channel includes three-dimensional interconnected non-directional pores, which further enhances the absorption and retention of electrolyte and improves the effect of suppressing convection of electrolyte.

[0009] In some embodiments, the pore channel includes a plurality of uniformly distributed pores, all of which extend axially along the polymer separator.

[0010] In the technical solution of this application, the pore channel includes uniformly distributed and non-interconnected directional pores, which can also enhance the absorption and retention of electrolyte, thereby improving the effect of suppressing convection of electrolyte.

[0011] In some embodiments, the aperture of the hole is 20μm-70μm.

[0012] In the technical solution of this application, the pores are set at the micron level. The micron-level pores ensure that the electrolyte can pass through smoothly while having a certain flow resistance, thereby enhancing the retention effect of the electrolyte.

[0013] In some embodiments, the first limiting groove and the second limiting groove are aligned.

[0014] In the technical solution of this application, setting the first limiting groove and the second limiting groove to be aligned can improve the symmetry of the positive and negative working areas and reduce the test error caused by the temperature of the structural assembly precision.

[0015] In some embodiments, the central regions of the first limiting groove and the second limiting groove are provided with the hole channel.

[0016] In the technical solution of this application, the first limiting groove and the second limiting groove are used to fix the positive electrode and the negative electrode, respectively, and the hole channel is set in the central area of ​​the first limiting groove and the second limiting groove so that the electrolyte can be evenly distributed between the positive electrode and the negative electrode.

[0017] In some embodiments, the polymer isolation plate is made of a thermoplastic polymer.

[0018] In the technical solution of this application, the thermoplastic polymer can melt when heated and resolidify and harden after cooling, which is beneficial for producing polymer isolation plates through fused deposition modeling technology.

[0019] In some embodiments, the polymer separator is made of at least one of polyethylene, polypropylene, polyamide, polyurethane, polyvinyl alcohol, polyvinyl composite material, polypropylene composite material, polyamide composite material, polyurethane composite material, and polyvinyl alcohol composite material.

[0020] In the technical solution of this application, the above-mentioned material can not only melt when heated and resolidify and harden after cooling, but also has high chemical stability in electrolyte.

[0021] Secondly, this application provides a method for preparing a polymer isolation plate, which uses fused deposition modeling to prepare a polymer isolation plate having a first limiting groove, a second limiting groove, and a pore channel.

[0022] In the technical solution of this application, fused deposition modeling can form a polymer separator in one step, resulting in high-quality products and high manufacturing efficiency. Furthermore, fused deposition modeling can fabricate a limiting groove that matches the electrode size, enabling precise electrode embedding.

[0023] In some embodiments, the "preparation of a polymer isolation plate having a first limiting groove, a second limiting groove, and a pore channel using fused deposition modeling" includes:

[0024] The porous channel area of ​​the polymer separator is printed using a thermoplastic polymer / foaming agent composite material, and the other areas of the polymer separator other than the porous channel area are printed using a thermoplastic polymer material.

[0025] In the technical solution of this application, fused deposition modeling combined with in-situ foaming process is used to create pore channel areas in local areas during the printing process, while other areas are dense structures, thus achieving one-time molding.

[0026] In some embodiments, "printing the pore channel region of the polymer separator with a thermoplastic polymer / foaming agent composite material" includes:

[0027] At a first temperature, a first nozzle extrudes and prints a thermoplastic polymer / foaming agent composite material, and the extruded thermoplastic polymer / foaming agent composite material is cooled and cured at a second temperature to form the pore channel region; the first temperature is not lower than the decomposition temperature of the foaming agent; and / or, the second temperature is 35%-55% of the first temperature.

[0028] In the technical solution of this application, at a first temperature, the foaming agent in the thermoplastic polymer / foaming agent composite material decomposes and releases gas to form pores. During the cooling and curing process at a second temperature, the pores are retained to form a three-dimensional interconnected pore channel region. A first temperature not lower than the decomposition temperature of the foaming agent allows for effective decomposition of the foaming agent to form a large number of pores; setting the second temperature to 35%-55% of the first temperature reduces warping caused by rapid cooling of the material and improves the quality of the pore channel region.

[0029] In some embodiments, "printing the polymer separator in a thermoplastic polymer material in areas other than the pore channel region" includes:

[0030] At a third temperature, thermoplastic polymer material is extruded and printed, and the extruded thermoplastic polymer material is cooled and cured at a fourth temperature to form regions other than the pore channel region; the third temperature is not lower than the melt processing temperature of the thermoplastic polymer; and / or, the fourth temperature is 35%-55% of the third temperature.

[0031] In the technical solution of this application, thermoplastic polymer material is directly printed to form other areas. These other areas have a dense structure, which can prevent short circuits caused by contact between positive and negative electrodes. The third temperature is not lower than the melt processing temperature of the thermoplastic polymer. At this temperature, the thermoplastic polymer material is in a molten state, which is beneficial for nozzle extrusion printing. The fourth temperature is set to 35%-55% of the third temperature, which can reduce warping caused by rapid cooling of the material and improve the quality of other areas.

[0032] In some embodiments, the printing rate is 180 mm / min-210 mm / min.

[0033] In the technical solution of this application, the printing rate within this range can be matched with the extrusion rate of the material, reducing the stretching or accumulation of the material, thereby improving the uniformity of the printing area and thus improving the printing quality.

[0034] In some embodiments, the preparation of the thermoplastic polymer / foaming agent composite material includes: mixing a thermoplastic polymer and a foaming agent in a screw extruder, and extruding at a fifth temperature to obtain a thermoplastic polymer / foaming agent composite filament, wherein the fifth temperature is not lower than the melt processing temperature of the thermoplastic polymer and lower than the decomposition temperature of the foaming agent; and / or,

[0035] The preparation of the thermoplastic polymer material includes: adding the thermoplastic polymer into a screw extruder and extruding it at a third temperature to obtain thermoplastic polymer filaments.

[0036] In the technical solution of this application, both the thermoplastic polymer / foaming agent composite material and the thermoplastic polymer material are processed into filaments by a screw extruder. The filament material is easier to replace and store than the powder material, and the material utilization rate is high.

[0037] In some embodiments, the mass ratio of the foaming agent to the thermoplastic polymer is (0.01-0.05):1.

[0038] In the technical solution of this application, the content of the foaming agent affects the porosity and pore structure of the pore channel region. When the content of the foaming agent is too low, the porosity is too low and insufficient to form a three-dimensional interconnected pore structure, which is not conducive to the wetting of the electrolyte. When the content of the foaming agent is too high, the porosity is too high and may form larger pores, which will affect the isolation effect.

[0039] In some embodiments, the foaming agent satisfies the following condition: the decomposition temperature of the foaming agent is within the melt processing temperature range of the thermoplastic polymer.

[0040] In the technical solution of this application, the first temperature and the third temperature can be set to be within the decomposition temperature range of the foaming agent, because the thermoplastic polymer is also in a molten state within this temperature range. That is, the printing of the pore channel area and other areas can be achieved at one temperature, simplifying the setting of printing process parameters.

[0041] In some embodiments, the foaming agent includes at least one of azodicarbonamide, p-toluenesulfonyl hydrazine, benzenesulfonyl hydrazine, and 5-phenyltetrazole.

[0042] In the technical solution of this application, the foaming agent can quickly decompose and release gases such as nitrogen when heated, and the resulting pores are more uniform.

[0043] Thirdly, this application proposes a polymer separator plate, which is prepared by the above-described method.

[0044] Fourthly, this application proposes a testing device, including an electrochemical workstation and the aforementioned test battery.

[0045] In the technical solution of this application, the overall structure of the testing device is simple and does not involve the assembly of multiple components, which can improve experimental efficiency and reduce testing errors caused by assembly accuracy issues.

[0046] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the structure of a test battery in one embodiment of this application;

[0048] Figure 2 This is a schematic diagram of the structure of the polymer separator in one embodiment of this application;

[0049] Figure 3 This is a schematic diagram of the printing device in one embodiment of this application;

[0050] Figure 4 This is a schematic diagram illustrating the preparation of a thermoplastic polymer / foaming agent composite material in one embodiment of this application;

[0051] Figure 5 This is a schematic diagram illustrating the preparation of a thermoplastic polymer material in one embodiment of this application;

[0052] Figure 6 This is a scanning electron microscope (SEM) image of a cross-section of the pore channel region of a polymer separator in one embodiment of this application. Attached image description:

[0054] 100. Test battery; 11. Polymer separator; 111. First limiting groove; 112. Hole channel; 1121. Hole; 12. Positive electrode; 13. Negative electrode; 14. Positive electrode current collector; 141. Positive electrode tab; 15. Negative electrode current collector; 151. Negative electrode tab;

[0055] 200. Printing device; 21. First printhead; 22. Printing platform; 23. Second printhead. Detailed Implementation

[0056] The following embodiments are only used to illustrate the technical solutions of this application more clearly, and are therefore only examples and should not be used to limit the scope of protection of this application.

[0057] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0058] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0059] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0060] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0061] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces). The term "at least one" refers to one or more.

[0062] In the testing and evaluation of electrode materials, reversibility, ion / electron transport kinetics, and electrolyte stability, symmetrical electrode devices are a classic testing structure. Traditional symmetrical electrode devices employ a separating membrane or plate between the positive and negative electrodes to confine the electrodes and suppress electrolyte convection.

[0063] Conventional symmetrical electrode devices place two lithium electrode plates on opposite sides of a insulating gel, which confines the working areas of the electrodes to ensure complete symmetry between the positive and negative electrodes. A through-hole is located at the center of the insulating gel, and a membrane is filled in this central through-hole to suppress the convection effect of the electrolyte caused by the concentration gradient. However, due to contact issues between the membrane and the through-hole in the insulating gel, a cavity exists between the membrane and the lithium electrode plate. This prevents effective suppression of the electrolyte convection effect, thus affecting the accurate measurement of electrolyte parameters. Therefore, methods to eliminate this cavity can be used to effectively suppress convection.

[0064] Based on the above considerations, this application provides a test battery, which includes a polymer separator. Two limiting grooves are formed on the two surfaces of the polymer separator, and through-hole channels are formed in the two limiting grooves. Positive and negative electrodes are respectively embedded in the two limiting grooves. At this time, the through-hole channels are located between the positive and negative electrodes and are in close contact with them, thereby effectively suppressing convection and improving the accuracy of experimental testing.

[0065] According to some embodiments of this application, reference is made to Figure 1 As shown, this application provides a test battery 100, including: a polymer separator 11, a positive electrode 12, a negative electrode 13, and an electrolyte; the polymer separator 11 has a first limiting groove 111 and a second limiting groove on its two opposite surfaces, and the first limiting groove 111 and the second limiting groove are connected through a hole channel 112; the positive electrode 12 and the negative electrode 13 are respectively disposed in the first limiting groove 111 and the second limiting groove; and the electrolyte is injected into the hole channel 112.

[0066] Test batteries are experimental batteries used to test and evaluate electrode materials, reversibility, ion / electron transport kinetics, and electrolyte stability. They are generally symmetrical electrode structures.

[0067] A separator is a component that physically separates the positive and negative electrodes, preventing them from directly contacting each other and causing an internal short circuit. A polymer separator is a separator made of polymer materials, possessing excellent electrical insulation properties. Except for the perforated channel 112, the remaining parts are a dense structure, effectively preventing short circuits caused by contact between the positive and negative electrodes.

[0068] refer to Figure 1 and 2As shown, the first limiting groove 111 and the second limiting groove are grooves for the positive and negative electrodes to be respectively embedded. The first limiting groove 111 and the second limiting groove are arranged back-to-back, serving a limiting function. The first limiting groove 111 and the second limiting groove should have a shape and size that match the positive and negative electrodes to ensure precise embedding of the positive and negative electrodes. Figure 2 For example, in this embodiment, both the first limiting groove 111 and the second limiting groove are circular grooves, and correspondingly, the positive electrode 12 and the negative electrode 13 are circular electrode sheets. Of course, in some other embodiments, the first limiting groove 111 and the second limiting groove can also be set to other shapes such as rectangles.

[0069] The positive electrode 12 and the negative electrode 13 can be lithium sheets or copper sheets, and the positive electrode 12 and the negative electrode 13 are the same. That is, the test battery in this application embodiment has a symmetrical electrode structure, which can be used to test the transport parameters of the electrolyte. The transport parameters include, but are not limited to, ion diffusion coefficient and ion transference number.

[0070] The aperture channel 112 refers to a structure formed between the first limiting groove 111 and the second limiting groove, allowing the electrolyte to flow. The aperture channel 112 enables the electrolyte to interconnect between the positive and negative electrodes. Figure 1 For example, the hole channel 112 can be set as a circular region, and the diameter of the circular region is smaller than the inner diameter of the first limiting groove 111 and the second limiting groove. In some other embodiments, the shape of the hole channel 112 region can be adjusted as needed.

[0071] In the test battery 100 of this application, the positive electrode 12 and the negative electrode 13 are bonded together on both sides of the pore channel 112, eliminating the presence of cavities and effectively improving the convection suppression effect of the electrolyte. The pore channel 112 also facilitates electrolyte absorption and enhances electrolyte retention. The frictional resistance of the pore wall of the pore channel 112 also effectively restricts electrolyte flow, playing a role in suppressing convection. In addition, the overall structure of the test battery 100 of this application is simple, not involving the assembly of multiple components, which can improve experimental efficiency and reduce test errors caused by assembly accuracy issues. Therefore, the polymer separator of this application can solve the problem of poor test accuracy.

[0072] According to some embodiments of this application, the aperture channel 112 includes a plurality of holes 1121, at least a portion of which are interconnected.

[0073] The interconnection of at least some of the pores 1121 includes all pores 1121 being interconnected, as well as some pores 1121 being closed while others are interconnected. That is, in some embodiments of this application, the pore channels 112 include three-dimensionally interconnected non-directional pores (pores 1121 are randomly distributed without specific directionality or regularity), forming a porous structure similar to a sponge. These porous structures further enhance the absorption and retention of electrolyte, thereby improving the effect of suppressing convection of the electrolyte.

[0074] According to some embodiments of this application, the hole channel 112 may also include a plurality of uniformly distributed holes 1121, all of which extend along the axial direction of the polymer separator 11.

[0075] The multiple holes 1121 extending along the axial direction of the polymer separator 11 means that the multiple holes 1121 are horizontally arranged between the first limiting groove 111 and the second limiting groove, and the multiple holes 1121 are distributed in parallel. That is, in some embodiments of this application, the pore channel 112 includes uniformly distributed and non-interconnected directional holes (the holes 1121 are arranged in a certain direction and pattern). This porous structure can also enhance the absorption and retention of electrolyte, so as to improve the effect of suppressing convection of electrolyte.

[0076] According to some embodiments of this application, the pore size of the hole 1121 is 20μm-70μm. That is, in some embodiments of this application, the hole 1121 can be set to the micrometer scale. The micrometer-scale pores ensure that the electrolyte can pass through smoothly while having a certain flow resistance, thereby enhancing the retention effect of the electrolyte.

[0077] According to some embodiments of this application, the first limiting groove 111 and the second limiting groove are aligned.

[0078] The first limiting groove 111 and the second limiting groove are aligned. By aligning the centers of the first limiting groove 111 and the second limiting groove, and ensuring they are identical in shape and size, the working areas of the positive and negative electrodes are completely symmetrical. In other words, aligning the first limiting groove 111 and the second limiting groove improves the symmetry of the positive and negative electrode working areas and reduces testing errors caused by structural assembly precision and temperature.

[0079] According to some embodiments of this application, reference is made to Figure 2 As shown, a hole channel 112 is provided in the central area of ​​the first limiting groove 111 and the second limiting groove.

[0080] The orifice channel 112 is located in the central region of the first limiting groove 111 and the second limiting groove, meaning that the orifice channel 112 region is concentrically arranged with the first limiting groove 111 and the second limiting groove. This allows the electrolyte to be evenly distributed between the positive and negative electrodes. Since the size of the orifice channel 112 region is smaller than the inner diameter of the first limiting groove 111 and the second limiting groove, in some other embodiments, the orifice channel 112 can also be located off-center, as long as the orifice channel 112 is located between the positive and negative electrodes.

[0081] In some embodiments, reference Figure 1 As shown, the test battery 100 also includes a positive current collector 14 and a negative current collector 15. The positive current collector 14 is attached to one side of the positive electrode 12, and the negative current collector 15 is attached to one side of the negative electrode 13. The positive current collector 14 and the negative current collector 15 can be aluminum foil or copper foil, and this application embodiment does not impose specific limitations. The positive current collector 14 is provided with a positive electrode tab 141, and the negative current collector 15 is provided with a negative electrode tab 151.

[0082] In some embodiments, the test battery may also include an outer packaging, which may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging of the test battery may also be a soft pack, such as a pouch. The soft pack may be made of plastic, and examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0083] According to some embodiments of this application, the polymer separator is made of thermoplastic polymer.

[0084] Thermoplastic polymers are polymer materials that melt when heated and can resolidify and harden after cooling. Using thermoplastic polymers is beneficial for producing polymer isolation panels through fused deposition modeling technology.

[0085] According to some embodiments of this application, the polymer separator is made of at least one of polyethylene, polypropylene, polyamide, polyurethane, polyvinyl alcohol, polyethylene-based composite material, polypropylene-based composite material, polyamide-based composite material, polyurethane-based composite material, and polyvinyl alcohol-based composite material.

[0086] Polyethylene-based composites refer to materials made by mixing polyethylene as a base material with fillers, reinforcing materials, or other polymers. For example, polyethylene-based composites can be selected from polyethylene-polypropylene composites, polyethylene-polystyrene composites, and polyethylene-polycarbonate composites. The same applies to polyamide-based composites, polyurethane-based composites, and polyvinyl alcohol-based composites.

[0087] The aforementioned materials not only melt when heated and resolidify and harden after cooling, but also exhibit high chemical stability in the electrolyte, thereby improving the stability of the battery.

[0088] According to some embodiments of this application, this application also provides a method for preparing a polymer isolation plate, which uses fused deposition modeling to prepare a polymer isolation plate having a first limiting groove, a second limiting groove, and a pore channel.

[0089] Fused deposition modeling (FDM) is a 3D printing method that builds objects layer by layer by heating and extruding material. FDM can produce polymer separators in a single process, resulting in high-quality products with high manufacturing efficiency. Furthermore, FDM can fabricate locating grooves that perfectly match the electrode dimensions, enabling precise electrode embedding.

[0090] According to some embodiments of this application, "preparing a polymer isolation plate having a first limiting groove, a second limiting groove, and a pore channel using fused deposition modeling" includes:

[0091] The porous channel area of ​​the polymer separator is printed using a thermoplastic polymer / foaming agent composite material, and the other areas of the polymer separator other than the porous channel area are printed using a thermoplastic polymer material.

[0092] Thermoplastic polymer / foaming agent composite material refers to a composite material formed by mixing thermoplastic polymer and foaming agent. The gas released by the decomposition of the foaming agent forms pores in the pore channel area. Some embodiments of this application adopt fused deposition modeling combined with in-situ foaming process to form pore channel areas in local pores during the printing process, while other areas are dense structures formed by printing thermoplastic polymer, realizing one-time molding.

[0093] According to some embodiments of this application, "printing the pore channel region of a polymer separator using a thermoplastic polymer / foaming agent composite material" includes:

[0094] At a first temperature, a thermoplastic polymer / foaming agent composite material is extruded and printed, and the extruded thermoplastic polymer / foaming agent composite material is cooled and cured at a second temperature to form a pore channel region; the first temperature is not lower than the decomposition temperature of the foaming agent; and / or, the second temperature is 35%-55% of the first temperature.

[0095] Extruding and printing the thermoplastic polymer / foaming agent composite material at the first temperature refers to setting the extrusion temperature of the thermoplastic polymer / foaming agent composite material as the first temperature. This first temperature, not lower than the decomposition temperature of the foaming agent, allows the foaming agent to effectively decompose and form numerous pores. During the cooling and curing process at the second temperature, these pores are retained, forming three-dimensional interconnected pore channels 112. Setting the second temperature to 35%-55% of the first temperature means that the value of the second temperature is 35%-55% of the value of the first temperature. For example, if the first temperature is 215℃, the second temperature can be set to 90℃. This reduces warping caused by rapid cooling of the material and improves the quality of the pore channel region.

[0096] The above methods and steps can be used Figure 3 The printing apparatus 200 shown exemplarily implements a thermoplastic polymer / foaming agent composite material being loaded into a first nozzle 21, with the temperature inside the first nozzle 21 controlled at a first temperature. The first nozzle 21 extrudes the thermoplastic polymer / foaming agent onto a printing platform 22, with the temperature of the printing platform 22 controlled at a second temperature. In this way, the extruded thermoplastic polymer / foaming agent composite material cools and solidifies on the printing platform 22 to form a pore channel 112.

[0097] According to some embodiments of this application, "printing polymer isolation plates in areas other than the pore channel areas using thermoplastic polymer materials" includes:

[0098] At a third temperature, the thermoplastic polymer material is extruded and printed. The extruded thermoplastic polymer material is cooled and cured at a fourth temperature to form regions other than the pore channel region. The third temperature is not lower than the melt processing temperature of the thermoplastic polymer. And / or, the fourth temperature is 35%-55% of the third temperature.

[0099] Extruding and printing thermoplastic polymer material at the third temperature means setting the extrusion temperature of the thermoplastic polymer material to the third temperature, which is not lower than the melt processing temperature of the thermoplastic polymer. This ensures that the thermoplastic polymer is in a molten state at this temperature, which is beneficial for extrusion and printing. Setting the fourth temperature to 35%-55% of the third temperature can reduce warping caused by rapid cooling of the material and improve the quality of other areas. In some embodiments of this application, thermoplastic polymer material is directly used to print areas other than the hole channel 112, which improves the density of other areas and can prevent short circuits caused by positive and negative electrode contact.

[0100] The above methods and steps can also be used. Figure 3The printing apparatus 200 shown exemplarily implements a process in which thermoplastic polymer material is loaded into a second nozzle 23, the temperature inside the second nozzle 23 is controlled at a third temperature, the second nozzle 23 extrudes the thermoplastic polymer onto a printing platform 22, and the temperature of the printing platform 22 is controlled at a fourth temperature, so that the extruded thermoplastic polymer material cools and solidifies on the printing platform 22 to form areas other than the pore channel 112.

[0101] According to some embodiments of this application, the printing rate is 180 mm / min-210 mm / min.

[0102] Printing rate refers to the material movement rate, specifically the movement rate of the first nozzle 21 and the second nozzle 23. The printing rate needs to be set to correspond to the material extrusion rate. Since the extrusion rate of the printhead is generally relatively fixed, this embodiment only limits the movement rate of the printhead. This range of printing rates can match the material extrusion rate, reducing material stretching or accumulation, thereby improving the uniformity of the printed area and ultimately improving print quality.

[0103] According to some embodiments of this application, the preparation of a thermoplastic polymer / foaming agent composite material includes: adding a thermoplastic polymer and a foaming agent to a screw extruder for mixing, and extruding at a fifth temperature to obtain a thermoplastic polymer / foaming agent composite filament, wherein the fifth temperature is not lower than the melt processing temperature of the thermoplastic polymer and is lower than the decomposition temperature of the foaming agent; and / or, the preparation of a thermoplastic polymer material includes: adding a thermoplastic polymer to a screw extruder and extruding at a third temperature to obtain a thermoplastic polymer filament.

[0104] The fifth temperature, which is not lower than the melt processing temperature of the thermoplastic polymer and lower than the decomposition temperature of the foaming agent, means that the fifth temperature must not only ensure that the thermoplastic polymer is in a molten state at this temperature, but also that the foaming agent will not decompose at this temperature. This allows the foaming agent to decompose and release gas during the extrusion printing process, thereby improving the porosity.

[0105] refer to Figure 4 As shown, thermoplastic polymer granules / powder and foaming agent powder are added to the screw extruder through the feed port for mixing. The temperature inside the screw extruder is controlled at the fifth temperature. Under the action of screw rotation and heating, the thermoplastic polymer is in a molten state, while the foaming agent is uniformly dispersed in the molten thermoplastic polymer in a powder state to form a mixture. Then the mixture moves to the end of the screw and is extruded through the die to form thermoplastic polymer / foaming agent composite filaments.

[0106] refer to Figure 5As shown, thermoplastic polymer granules / powders are fed into the screw extruder through the feed inlet. The temperature inside the screw extruder is controlled at the third temperature. Under the rotation and heating action of the screw, the thermoplastic polymer is in a molten state. Then, the molten thermoplastic polymer moves to the end of the screw and is extruded through the die to form thermoplastic polymer filaments.

[0107] Both thermoplastic polymer / foaming agent composites and thermoplastic polymer materials are processed into filaments using a screw extruder. Filament materials are easier to replace and store than powder materials, and have a higher material utilization rate.

[0108] According to some embodiments of the present invention, the mass ratio of foaming agent to thermoplastic polymer is (0.01-0.05):1.

[0109] The content of foaming agent affects the porosity and pore structure of the pore channel region. When the content of foaming agent is too low, the porosity is too low to form a three-dimensional interconnected pore structure, which is not conducive to the wetting of electrolyte. When the content of foaming agent is too high, the porosity is too high, which may form larger pores, thus affecting the isolation effect.

[0110] According to some embodiments of the present invention, the foaming agent satisfies the following condition: the decomposition temperature of the foaming agent is located within the melt processing temperature range of the thermoplastic polymer.

[0111] The decomposition temperature of the foaming agent falling within the melt processing temperature range of the thermoplastic polymer means that the decomposition temperature of the foaming agent is greater than the lower limit of the lower melt temperature of the thermoplastic polymer but less than the upper melt temperature of the thermoplastic polymer. This allows setting both the first and third temperatures within the decomposition temperature range of the foaming agent, because the thermoplastic polymer is also in a molten state within this temperature range. This means that the printing of the pore channel area and other areas can be achieved at a single temperature, simplifying the setting of printing process parameters.

[0112] According to some embodiments of the present invention, the foaming agent includes at least one selected from azodicarbonamide, p-toluenesulfonyl hydrazine, benzenesulfonyl hydrazine, and 5-phenyltetrazole. The above-mentioned foaming agent can rapidly decompose and release gases such as nitrogen when heated, and the resulting pores are more uniform.

[0113] Among them, the decomposition temperature of azodicarbonamide is 205℃-215℃, that of p-toluenesulfonyl hydrazine is 110℃-120℃, that of benzenesulfonyl hydrazine is 157℃-160℃, and that of 5-phenyltetrazole is 240℃-250℃.

[0114] The melt processing temperature of polyethylene is 120℃-180℃. When polyethylene is selected as the thermoplastic polymer, p-toluenesulfonyl hydrazine or benzenesulfonyl hydrazine can be chosen as the corresponding blowing agent. The melt processing temperature of polypropylene is 180℃-310℃. When polypropylene is selected as the thermoplastic polymer, azodicarbonamide or 5-phenyltetrazole can be chosen as the corresponding blowing agent. The melt processing temperature of polyamide is 230℃-260℃. When polyamide is selected as the thermoplastic polymer, 5-phenyltetrazole can be chosen as the corresponding blowing agent. The melt processing temperature of polyurethane is 100℃-200℃. When polyurethane is selected as the thermoplastic polymer, p-toluenesulfonyl hydrazine or benzenesulfonyl hydrazine can be chosen as the corresponding blowing agent.

[0115] According to some embodiments of this application, this application also proposes a polymer separator plate, which is prepared by the above-described preparation method.

[0116] According to some embodiments of this application, this application also proposes a testing device, including an electrochemical workstation and the aforementioned test battery 100. The specific structure of the test battery 100 is as described in the above embodiments. Since the testing device adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, and will not be described in detail here.

[0117] Example

[0118] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0119] Example 1

[0120] A testing device, reference Figure 1 As shown, it includes: a polymer separator 11, a positive electrode 12, a negative electrode 13, an electrolyte, a positive electrode current collector 14, a negative electrode current collector 15, and an electrochemical workstation.

[0121] The polymer separator 11 has a first limiting groove 111 on its left side and a second limiting groove on its right side. The first limiting groove 111 and the second limiting groove are connected by a perforated channel 112, which includes multiple holes 1131. At least a portion of the multiple holes 1131 are interconnected to form a three-dimensional interconnected non-directional porous structure. The positive electrode 12 is embedded in the first limiting groove 111, and the negative electrode 13 is embedded in the second limiting groove. Both the positive electrode 12 and the negative electrode 13 are lithium sheets with a diameter of 14 mm and a thickness of 0.5 mm.

[0122] The electrolyte comprises an electrolyte and a solvent. The electrolyte is lithium hexafluorophosphate (LiPF6), and the solvent is a mixture of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) with a volume ratio of EC to EMC of 3:7. The concentration of the electrolyte is 1 mol / L. The electrolyte is injected between the positive electrode 12 and the negative electrode 13, and located at the pore channel 112.

[0123] The positive current collector 14 is attached to the left side of the positive electrode 12, and the negative current collector 15 is attached to the right side of the negative electrode 13. The top of the positive current collector 14 is provided with a positive electrode tab 141, and the top of the negative current collector 15 is provided with a negative electrode tab 151. The positive electrode tab 141 and the negative electrode tab 151 are connected to the electrochemical workstation. Both the positive current collector 14 and the negative current collector 15 are copper foils with a size of 50mm × 50mm.

[0124] refer to Figure 3-5 As shown, the preparation method of the polymer separator includes:

[0125] (1) Add 1 kg of polypropylene granules to a single screw extruder, set the extrusion temperature to 190℃, and extrude polypropylene filaments with a diameter of 1.75 mm through the single screw extruder;

[0126] (2) Add 1 kg of polypropylene granules and 50 g of azodicarbonamide powder to a single screw extruder for melt blending. Set the extrusion temperature to 190°C and extrude polypropylene / azodicarbonamide composite filaments with a diameter of 1.75 mm through the single screw extruder.

[0127] (3) The polypropylene / azodicarbonamide composite filament is loaded into the first nozzle 21 and the polypropylene filament is loaded into the second nozzle 23. The diameter of the first nozzle 21 and the second nozzle 23 is 0.4 mm. The extrusion temperature of the first nozzle 21 and the second nozzle 23 is set to 215℃, the moving speed of the first nozzle 21 and the second nozzle 23 is 200 mm / min, and the temperature of the printing platform 22 is set to 90℃. Then, the three-dimensional model is imported and printing is started.

[0128] (4) The second nozzle 23 prints the dense area around the polymer isolation plate. After printing, the first nozzle 21 quickly moves to the central area for printing. During the printing process, the azodicarbonamide foaming agent decomposes and releases carbon dioxide and nitrogen when the polypropylene is in a molten state, forming a large number of micron-sized bubble channels within the polypropylene. When the central area cools and solidifies, a three-dimensional interconnected micron-sized porous structure (pore channel) is formed. The scanning electron microscope image of the pore channel area after brittle fracture is shown below. Figure 6As shown, the pore channel region has a three-dimensional interconnected porous structure; the final processed polypropylene partition plate has an appearance of 50x50x1.4 mm; the diameter of the circular limiting groove is 14 mm and the depth is 0.5 mm; the diameter of the pore channel region is 10 mm and the thickness is 0.4 mm.

[0129] Example 2

[0130] Unlike Example 1, the amount of azodicarbonamide foaming agent added in this example is 10g. The rest of the structure is the same as in Example 1.

[0131] Example 3

[0132] Unlike Embodiment 1, the pore channel 112 in this embodiment includes a plurality of holes 1131, which are evenly distributed and extend circumferentially along the polymer separator 11. That is, the pore channel 112 in this embodiment is a non-interconnected directional hole structure. The rest of the structure is the same as in Embodiment 1.

[0133] Example 4

[0134] Unlike Example 1, this example uses polyethylene granules and benzenesulfonyl hydrazine powder as raw materials. In steps (1) and (2) of the polymer separator preparation method, the extrusion temperature is set to 130°C; in step (3), the extrusion temperature of the first nozzle 21 and the second nozzle 23 is set to 160°C, and the temperature of the printing platform 22 is set to 65°C. The remaining structure is the same as in Example 1.

[0135] Example 5

[0136] Unlike Example 1, this example uses polyurethane granules and p-toluenesulfonyl hydrazine powder as raw materials. In steps (1) and (2) of the polymer separator preparation method, the extrusion temperature is set to 105°C; in step (3), the extrusion temperature of the first nozzle 21 and the second nozzle 23 is set to 120°C, and the temperature of the printing platform 22 is set to 45°C. The remaining structure is the same as in Example 1.

[0137] Comparative Example

[0138] A testing device includes a positive electrode, a negative electrode, a separator, an electrolyte, a positive electrode current collector, and a negative electrode current collector. Both the positive and negative electrodes are lithium sheets with a diameter of 14 mm and a thickness of 0.5 mm. The separator, with a thickness of 0.4 mm, is disposed between the positive and negative electrodes and is impregnated with the electrolyte. The positive electrode current collector is disposed on one side of the positive electrode, and the negative electrode current collector is disposed on the other side of the negative electrode. Both the positive and negative electrode current collectors are copper foils with dimensions of 50 mm × 50 mm. The positive electrode current collector, positive electrode, separator, negative electrode, and negative electrode current collector are sequentially pressed together and then encapsulated.

[0139] Performance testing

[0140] The testing apparatus of Examples 1-5 and the comparative examples described above was used to determine the lithium-ion transport number in the electrolyte. The determination method included:

[0141] Based on the Bruce-Vincent method, a small and constant potential difference is applied to the electrodes, and the change in current over time is recorded. The initial current, where all mobile components contribute to charge transport, is denoted as I. 0 As polarization proceeds, a stable concentration gradient forms in the system, inhibiting the migration of anions. Only cations move directionally under the influence of the electric field, and at this point, the current tends to stabilize, which is called the steady-state current I. SS The formula for calculating the lithium-ion transport number is shown in Equation (I).

[0142] t + =[I ss R b ss (ΔV-I 0R el 0 )] / [I 0 R b 0 (ΔV-I ss R el ss )] Formula (I)

[0143] Where: ΔV is the voltage applied across the battery terminals, I 0 For the initial current, R el 0 For the initial electrode reaction resistance, I ss For steady-state current, R el ss For steady-state electrode reaction resistance, Rb 0 For the initial electrolyte resistance, R b ss This is the steady-state electrolyte resistance.

[0144] Test Results

[0145] The test results are shown in Table 1.

[0146] Table 1. Test results from Examples 1-5 and comparative examples.

[0147]

[0148]

[0149] As can be seen from the table above, the standard deviation of the migration number measured by the test device in this embodiment is smaller than the standard deviation of the test device in the comparative example, indicating that the test device in this embodiment can improve the test accuracy when testing the migration number.

[0150] The above description is merely an exemplary embodiment of this application and does not limit the patent scope of this application. Any equivalent structural transformations made based on the technical concept of this application and the contents of the specification and drawings of this application, or direct / indirect applications in other related technical fields, are included within the patent protection scope of this application.

Claims

1. A test battery, characterized in that, include: The polymer separator includes a positive electrode, a negative electrode, and an electrolyte. The polymer separator has a first limiting groove and a second limiting groove on its two opposite surfaces, and the first limiting groove and the second limiting groove are connected by a hole channel. The positive and negative electrodes are respectively disposed in the first limiting groove and the second limiting groove; The electrolyte is injected into the pore channel.

2. The test battery as described in claim 1, characterized in that, The channel includes a plurality of holes, at least a portion of which are interconnected.

3. The test battery as described in claim 1, characterized in that, The pore channel includes a plurality of evenly distributed pores, all of which extend along the axial direction of the polymer separator.

4. The test battery as described in claim 2 or 3, characterized in that, The aperture of the hole is 20μm-70μm.

5. The test battery as described in claim 1, characterized in that, The first limiting groove and the second limiting groove are aligned.

6. The test battery as described in claim 5, characterized in that, The central area of ​​the first limiting groove and the second limiting groove is provided with the hole channel.

7. The test battery as described in claim 1, characterized in that, The polymer isolation plate is made of thermoplastic polymer.

8. The test battery as described in claim 7, characterized in that, The polymer separator is made of at least one of polyethylene, polypropylene, polyamide, polyurethane, polyvinyl alcohol, polyvinyl composite material, polypropylene composite material, polyamide composite material, polyurethane composite material, and polyvinyl alcohol composite material.

9. A method for preparing a polymer separator, characterized in that, A polymer isolation plate with a first limiting groove, a second limiting groove, and a pore channel was prepared by fused deposition modeling.

10. The method for preparing the polymer separator as described in claim 9, characterized in that, The "preparation of a polymer isolation plate with a first limiting groove, a second limiting groove, and a pore channel using fused deposition modeling" includes: The porous channel area of ​​the polymer separator is printed using a thermoplastic polymer / foaming agent composite material, and the other areas of the polymer separator other than the porous channel area are printed using a thermoplastic polymer material.

11. The method for preparing the polymer separator as described in claim 10, characterized in that, The phrase "printing the pore channel region of the polymer separator using a thermoplastic polymer / foaming agent composite material" includes: At a first temperature, a thermoplastic polymer / foaming agent composite material is extruded and printed, and the extruded thermoplastic polymer / foaming agent composite material is cooled and cured at a second temperature to form the pore channel region; The first temperature is not lower than the decomposition temperature of the foaming agent; and / or, the second temperature is 35%-55% of the first temperature.

12. The method for preparing the polymer separator as described in claim 10, characterized in that, The phrase "printing the polymer isolation plate with thermoplastic polymer material in areas other than the pore channel region" includes: At a third temperature, the thermoplastic polymer material is extruded and printed, and the extruded thermoplastic polymer material is cooled and cured at a fourth temperature to form areas other than the pore channel area; The third temperature is not lower than the melt processing temperature of the thermoplastic polymer, and / or the fourth temperature is 35%-55% of the third temperature.

13. The method for preparing the polymer separator as described in claim 11 or 12, characterized in that, The printing speed is 180mm / min-210mm / min.

14. The method for preparing the polymer separator as described in claim 10 or 11, characterized in that, The preparation of the thermoplastic polymer / foaming agent composite material includes: A thermoplastic polymer and a foaming agent are mixed in a screw extruder and extruded at a fifth temperature to obtain a thermoplastic polymer / foaming agent composite filament, wherein the fifth temperature is not lower than the melt processing temperature of the thermoplastic polymer and lower than the decomposition temperature of the foaming agent; and / or, The preparation of the thermoplastic polymer material includes: Thermoplastic polymer is added to a screw extruder and extruded at a third temperature to obtain thermoplastic polymer filaments.

15. The method for preparing the polymer separator as described in claim 14, characterized in that, The mass ratio of the foaming agent to the thermoplastic polymer is (0.01-0.05):

1.

16. The method for preparing the polymer separator as described in claim 14, characterized in that, The foaming agent satisfies the following condition: the decomposition temperature of the foaming agent is within the melt processing temperature range of the thermoplastic polymer.

17. The method for preparing the polymer separator as described in claim 16, characterized in that, The foaming agent includes at least one of azodicarbonamide, p-toluenesulfonyl hydrazine, benzenesulfonyl hydrazine, and 5-phenyltetrazole.

18. A polymer separator, characterized in that, It is prepared by the preparation method according to any one of claims 9 to 17.

19. A testing device, characterized in that, Includes an electrochemical workstation and a test cell as described in any one of claims 1 to 8.

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