Diaphragm, method of manufacturing electrode, battery, and electric device

Abstract

This application relates to the field of batteries, specifically disclosing a separator, a method for preparing electrode cores, a battery, and electrical equipment. The separator includes: a separator body; and a dye layer disposed at the tail end of the separator body, the dye layer comprising volatile dyes. The volatile dyes used in this application can not only dye the tail end of the separator body, but also disappear or weaken due to heat or light exposure after separator assembly, thereby avoiding or reducing the impact of dye entering the battery system on battery performance and maintaining the stability of the battery system.

Description

Technical Field

[0001] This application belongs to the field of battery technology, specifically relating to a separator, a method for preparing electrode cores, a battery, and an electrical device. Background Technology

[0002] During the assembly of lithium-ion batteries (such as stacking or winding), unexpected shutdowns often occur, leading to misjudgments of the remaining separator length. This results in incomplete assembly and waste due to insufficient separator length. To reduce such waste, a common method is to spray dyes containing the positive and negative electrode materials onto the separator's tail end. This involves spraying dye onto the separator at a distance from the tail end, allowing for early identification of the separator's tail end during assembly and reminding personnel to replace the separator material.

[0003] However, most of the dyes used in the positive and negative electrode materials of the separators currently used in lithium-ion batteries can affect the performance of the battery to varying degrees, leading to instability or even sudden changes in the battery's electrical performance. Summary of the Invention

[0004] This application aims to at least partially address one of the technical problems in related technologies. Therefore, the purpose of this application is to provide a separator, a method for preparing the electrode core, a battery, and an electrical device. The volatile dye used in this application can not only dye the tail end of the separator body, but also disappear or weaken due to heat or light exposure after the separator assembly is completed. This avoids or reduces the impact of dye entering the battery system on battery performance, thus maintaining the stability of the battery system.

[0005] In one aspect of this application, a diaphragm is provided. According to an embodiment of this application, the diaphragm comprises:

[0006] diaphragm body;

[0007] A dye layer is disposed at the tail end of the diaphragm body, and the dye layer includes volatile dyes.

[0008] According to the embodiments of this application, the separator body is dyed with volatile dyes at its tail end. This allows for early identification of the separator tail end during assembly, reminding relevant personnel to replace the separator material and avoiding misjudgment of the remaining separator length. Simultaneously, the volatile dye at the separator tail end can disappear or weaken due to heat or light exposure after separator assembly, thereby preventing or reducing the impact of dye entering the battery system on battery performance and maintaining the stability of the battery system.

[0009] In addition, the diaphragm according to the above embodiments of this application may also have the following additional technical features:

[0010] In some embodiments of this application, the volatile dye has an evaporation temperature of 40°C-150°C.

[0011] In some embodiments of this application, the volatile dye includes at least one of iodine dyes, stannous ester dyes, methylene blue dyes, cucurbitacin dyes, and formaldehyde blue dyes.

[0012] In some embodiments of this application, the stannous dye includes at least one of stannous yellow, stannous orange, stannous red, stannous blue, stannous violet, and stannous green; and / or, the methylene blue dye includes at least one of methylene blue, methylene blue 5B, methylene blue 6BX, and methylene blue AZ.

[0013] In some embodiments of this application, the stannous yellow includes at least one of stannous yellow 2G and stannous yellow 3G; and / or, the stannous orange includes at least one of stannous orange 2G and stannous orange 3G; and / or, the stannous red includes at least one of stannous red G, stannous red GR, and stannous red 3R; and / or, the stannous blue includes at least one of stannous blue 2R and stannous blue 3R; and / or, the stannous violet includes at least one of stannous violet 2R and stannous violet 3R; and / or, the stannous green includes at least one of stannous green 2G and stannous green 3G.

[0014] In some embodiments of this application, the width of the dye layer along the assembly direction of the diaphragm is 0.7cm-1.3cm.

[0015] In a second aspect, this application proposes a method for preparing an electrode core. According to an embodiment of this application, the method includes:

[0016] Obtain a diaphragm with a dye layer comprising a volatile dye;

[0017] The diaphragm with the dye layer is assembled into an electrode core;

[0018] The electrode core is subjected to hot pressing and / or light irradiation treatment to cause the volatile dyes in the dye layer to evaporate.

[0019] In some embodiments of this application, obtaining a diaphragm with a dye layer includes: coating a volatile dye solution onto the tail end of the diaphragm body, drying, and forming the dye layer at the tail end of the diaphragm body.

[0020] According to the method for preparing the electrode core according to the embodiments of this application, the method uses volatile dyes to print dye on the tail end of the separator body. This serves to identify the tail end of the separator in advance during the assembly of the separator into the electrode core, reminding relevant personnel to replace the separator material and avoiding misjudgment of the remaining separator length. Simultaneously, the volatile dye at the tail end of the separator disappears or weakens after the separator assembly is completed due to heat or light exposure, thereby avoiding or reducing the impact of dye entering the battery system on battery performance and maintaining the stability of the battery system.

[0021] In addition, the method for preparing the electrode core according to the above embodiments of this application may also have the following additional technical features:

[0022] In some embodiments of this application, the volatile dye is an iodine dye, and the concentration of the iodine dye in the iodine dye solution is 10 g / L-16 g / L.

[0023] In some embodiments of this application, the volatile dye is a stannous dye, and the concentration of the stannous dye in the stannous dye solution is 50 g / L-300 g / L.

[0024] In some embodiments of this application, the volatile dye is methylene blue dye, and the concentration of the methylene blue dye in the methylene blue dye solution is 12 g / L-25 g / L.

[0025] In some embodiments of this application, the volatile dye is a cucurbitacin dye, and the concentration of the cucurbitacin dye in the cucurbitacin dye solution is 5 g / L-25 g / L.

[0026] In some embodiments of this application, the volatile dye is formaldehyde blue dye, and the concentration of formaldehyde blue dye in the formaldehyde blue dye solution is 5 g / L-25 g / L.

[0027] In some embodiments of this application, the temperature of the hot pressing treatment is 80°C-150°C.

[0028] In a third aspect, this application proposes a battery. According to embodiments of this application, the battery includes the separator described in the above embodiments or the electrode core prepared by the method for preparing the electrode core described in the above embodiments. This avoids or reduces the impact of dye entering the battery system on battery performance, thus maintaining the stability of the battery system.

[0029] In a fourth aspect, this application proposes an electrical device. According to an embodiment of this application, the electrical device has the battery described above. Thus, the electrical device possesses all the advantages of a battery, which will not be elaborated further here.

[0030] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0031] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0032] Figure 1 This is a flowchart illustrating the method for preparing the electrode core according to an embodiment of this application. Detailed Implementation

[0033] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0034] This application was filed by the inventor based on the following questions:

[0035] In related technologies, most dyes used in lithium-ion battery separators are dyes that enter the battery system along with the separator. The introduction of these dyes can affect battery performance to varying degrees, leading to instability or even sudden performance changes. For example, using cathode material dyes as separator dyes can reduce the battery's initial coulombic efficiency. Simultaneously, if cathode dyes are coated on the negative electrode side, they can easily cause short circuits and lithium plating, reducing battery safety. Introducing negative electrode materials as dyes into the battery system can reduce battery capacity; similarly, if negative electrode materials are coated on the positive electrode separator side, they can easily cause lithium plating and short circuits, reducing battery safety. Furthermore, if the coating thickness is not precisely controlled, it can increase the battery's thickness, increasing volume changes during charging and discharging, thereby reducing battery life and safety, and increasing the risk of battery failure.

[0036] In view of this, in one aspect of this application, a separator is proposed. According to an embodiment of this application, the separator includes: a separator body; and a dye layer disposed at the tail end of the separator body, the dye layer comprising a volatile dye. Thus, the volatile dye used in this application can not only dye the tail end of the separator body, but also disappear or weaken due to heat or light exposure after the separator assembly is completed, thereby avoiding or reducing the impact of dye entering the battery system on battery performance and maintaining the stability of the battery system.

[0037] The principle by which the diaphragm proposed in this application achieves the above-mentioned beneficial effects will be explained in detail below:

[0038] This application uses volatile dyes to print on the tail end of the separator body. This allows for early identification of the separator tail end during assembly (e.g., stacking or winding), reminding relevant personnel to replace the separator material and avoiding misjudgment of the remaining separator length. Simultaneously, the volatile dye at the separator tail end disappears or weakens after separator assembly due to heat or light exposure, thereby preventing or reducing the impact of dye entering the battery system on battery performance and maintaining the stability of the battery system.

[0039] The dye described in this application is volatile and can volatilize upon high-temperature heating or under light irradiation, thus classifying it as a volatile dye. A volatile dye is a special type of dye that, without requiring dissolution or chemical reaction, rapidly transforms its molecular structure from a solid to a gaseous state under heating or light irradiation.

[0040] Taking iodine dye as an example, its main component is iodine. Not only can the dyeing color be adjusted by the interaction between iodine molecules and the membrane material, enabling dyeing of the membrane tail end at room temperature, but also the iodine dye can be directly converted from solid to gaseous state by appropriately adjusting the temperature or air pressure, achieving the purpose of volatilization at high temperature.

[0041] According to some specific embodiments of this application, the volatilization temperature of the above-mentioned volatile dye is 40℃-150℃, which can ensure that it volatilizes during the subsequent hot pressing process, thereby avoiding or reducing the impact of the dye entering the battery system on the battery performance and maintaining the stability of the battery system.

[0042] According to further specific embodiments of this application, the aforementioned volatile dyes include at least one of iodine dyes, stannous ester dyes, methylene blue dyes, guar gum dyes, and formaldehyde blue dyes. Therefore, the aforementioned types of volatile dyes can be used to dye the tail end of the separator body. Furthermore, these types of volatile dyes can disappear or weaken due to heat or light exposure after the separator assembly is completed, thereby avoiding or reducing the impact of dyes entering the battery system on battery performance and maintaining the stability of the battery system. Preferably, at least one of stannous ester dyes, methylene blue dyes, guar gum dyes, and formaldehyde blue dyes is used, and more preferably, methylene blue dyes are used.

[0043] In the embodiments of this application, the iodine dye can be a commercially available conventional iodine dye or a high-concentration iodine dye. The concentration of the dye is appropriately adjusted by adding solvent, and then it is placed in a well-sealed spraying device. The storage temperature should not exceed 40°C. Alternatively, the iodine dye can be prepared by the user. The preparation process is as follows: take a certain amount of iodine and potassium iodide, dissolve them in deionized water, shake well, and obtain an iodine dye solution with a concentration of 10g / L-16g / L. The iodine dye is stored in a well-sealed spraying device, and the spraying effect of the iodine dye solution is tested on the diaphragm to be sprayed to ensure that the color is bright and can be recognized by the machine. If the color is not bright enough, the amount of deionized water can be reduced and the concentration of iodine dye increased.

[0044] The environment for using iodine dye: Set the temperature of the diaphragm production and storage environment to ≤45℃, and keep it below 40℃ as much as possible. Use a spraying device containing iodine dye solution to spray and dye the diaphragm at the tail end, let it air dry naturally, and store the diaphragm at room temperature.

[0045] Iodine dye volatilization conditions: The environment for assembling the separator must be strictly controlled according to the battery-grade dew point. After assembly, the assembled electrode is subjected to hot pressing treatment (the temperature is greater than 45℃ to achieve the sublimation of iodine dye). There is no need to set the temperature and drying time separately for the volatilization of iodine dye.

[0046] It should be noted that during the assembly process (e.g., stacking or winding), the separator is placed between the positive and negative electrode plates, and then the stacking or winding is performed.

[0047] In the embodiments of this application, the temperature at which methylene blue dye begins to evaporate is approximately 100°C-120°C.

[0048] In the embodiments of this application, the specific type of methylene blue dye is not particularly limited. As some specific examples, the methylene blue dye includes at least one of methylene blue, methylene blue 5B, methylene blue 6BX, and methylene blue AZ. All of the above types of methylene blue dyes can be used to dye the diaphragm. Preferably, methylene blue AZ, which is suitable for dyeing cotton fibers, is used to dye the diaphragm.

[0049] The following description uses methylene blue AZ as an example to illustrate the use of methylene blue dye:

[0050] In the embodiments of this application, the above-mentioned methylene blue AZ dye solution can be directly purchased as a standard solution. However, the concentration of the standard solution is low, and the dyeing effect on the diaphragm is not obvious. Therefore, the dye solution can be prepared by purchasing methylene blue AZ powder. The preparation process is as follows: take a certain amount of methylene blue AZ powder and bake it in an oven for 1 to 10 hours at a baking temperature ≤100℃ to obtain methylene blue AZ powder. Dissolve it in deionized water and stir for 0 to 60 minutes to obtain a methylene blue AZ solution with a concentration of 12g / L-21g / L. Then, transfer the prepared methylene blue AZ solution to a prepared spraying device for storage and use. The usage period is 28 days, and the storage temperature is ≤40℃. To ensure the effect after dye spraying, take the diaphragm to be sprayed for a spraying experiment to observe the color state of the diaphragm after spraying and whether it can be recognized by the machine. Adjust the appropriate concentration before actual diaphragm spraying production application.

[0051] In the embodiments of this application, the usage environment of methylene blue dye is as follows: the ambient temperature for separator production is set to ≤40℃, and the separator after spraying is stored away from light. Simultaneously, the ambient temperature during separator assembly must be ≤40℃, and direct sunlight must be avoided to ensure that the methylene blue dye does not fade during machine recognition. During the baking stage after assembly, the temperature setting can be adjusted according to the battery manufacturing process.

[0052] The volatilization conditions for methylene blue dye: After assembling the separator, the assembled electrodes undergo baking and hot pressing. Baking conditions follow lithium-ion battery manufacturing processes, and the hot pressing temperature must be ≥100℃ to ensure the methylene blue dye on the separator volatilizes due to the high temperature. Alternatively, after assembly, the identified separator can be irradiated with ultraviolet light. Under light exposure, the methylene blue dye will volatilize, thus preventing excessive introduction of methylene blue dye into the battery system and avoiding any impact on its electrical performance.

[0053] In the embodiments of this application, the specific types of stannous dyes are not particularly limited. As some specific examples, the stannous dyes include at least one of stannous yellow, stannous orange, stannous red, stannous blue, stannous violet, and stannous green. Stannous yellow includes stannous yellow 2G, stannous yellow 3G, etc. Stannous orange includes stannous orange 2G, stannous orange 3G, etc. Stannous red includes stannous red G, stannous red GR, stannous red 3R, etc. Stannous blue includes stannous blue 2R, stannous blue 3R, etc. Stannous violet includes stannous violet 2R, stannous violet 3R, etc. Stannous green includes stannous green 2G, stannous green 3G, etc. All of the above-mentioned types of stannous dyes can disappear or weaken due to heat after the separator assembly is completed, thereby avoiding or reducing the impact of dyes entering the battery system on battery performance and maintaining the stability of the battery system.

[0054] The following description uses Stannous Red G as an example to illustrate the use of stannous dyes:

[0055] Preparation and storage of stannous red G dye: Select a stannous red G dye solution with a mass concentration of 50 g / L-300 g / L and store it in a well-sealed spraying device. To ensure the effect of dye spraying, take the diaphragm to be sprayed for a spraying experiment, observe the color state of the diaphragm after spraying, and see if it can be recognized by the machine. Adjust the appropriate concentration before actual diaphragm spraying production application.

[0056] The operating environment for stannous red G dye is as follows: the temperature of the environment for use and storage should be ≤100℃.

[0057] The volatilization conditions of stannous red G dye: After the separator is assembled, the assembled electrode sheets need to be baked and hot-pressed. The baking conditions can be set according to the design process of the lithium-ion cell, but the hot-pressing conditions must be specified at 150℃. After hot-pressing, the stannous red G dye on the separator will volatilize.

[0058] According to some specific embodiments of this application, the width of the dye layer (i.e., the width along the stacking direction or winding direction) is 0.7cm-1.3cm. A dye layer of a certain width can further play the role of identifying the tail end of the diaphragm, reminding relevant personnel to replace the diaphragm material, and avoiding misjudgment of the remaining diaphragm length.

[0059] In a second aspect, this application proposes a method for preparing an electrode core. According to embodiments of this application, refer to the appendix... Figure 1 It includes the following steps:

[0060] S100: Obtain a diaphragm with a dye layer, the dye layer including volatile dyes;

[0061] In this step, a diaphragm with a dye layer, including volatile dyes, is obtained. This serves to identify the end of the diaphragm in advance during the assembly of the diaphragm with the dye layer into the electrode core (e.g., during the stacking or winding of the diaphragm), reminding relevant personnel to replace the diaphragm material and avoiding misjudgment of the remaining diaphragm length.

[0062] According to some specific embodiments of this application, obtaining a diaphragm with a dye layer includes: coating a volatile dye solution onto the tail end of the diaphragm body, drying, and forming a dye layer at the tail end of the diaphragm body.

[0063] In the embodiments of this application, the concentration of volatile dye in the volatile dye solution is related to the specific type of volatile dye. According to some specific embodiments of this application, when the volatile dye is an iodine dye, the concentration of the iodine dye in the iodine dye solution is 10 g / L-16 g / L, for example, it can be 10 g / L, 11 g / L, 12 g / L, 13 g / L, 14 g / L, 15 g / L, 16 g / L, etc. By limiting the concentration of the iodine dye solution within the above range, it is possible to further ensure that the iodine dye solution is uniformly coated on the tail end of the diaphragm body and ensure that the formed dye layer has a bright color that can be recognized by the machine.

[0064] According to some specific embodiments of this application, the volatile dye is a stannous dye, and the concentration of the stannous dye in the stannous dye solution is 50 g / L-300 g / L, for example, it can be 50 g / L, 60 g / L, 80 g / L, 100 g / L, 120 g / L, 140 g / L, 160 g / L, 180 g / L, 200 g / L, 220 g / L, 240 g / L, 260 g / L, 300 g / L, etc. By limiting the concentration of the stannous dye solution within the above range, it is possible to further ensure that the stannous dye solution is uniformly coated on the tail end of the diaphragm body and ensure that the formed dye layer has a bright color that can be recognized by the machine.

[0065] According to some specific embodiments of this application, the volatile dye is methylene blue dye, and the concentration of methylene blue dye in the methylene blue dye solution is 12g / L-25g / L, for example, it can be 12g / L, 13g / L, 14g / L, 15g / L, 16g / L, 17g / L, 18g / L, 19g / L, 20g / L, 21g / L, 25g / L, etc. By limiting the concentration of the methylene blue dye solution within the above range, it is possible to further ensure that the methylene blue dye solution is uniformly coated on the tail end of the diaphragm body and to ensure that the formed dye layer has a bright color that can be recognized by the machine.

[0066] According to some specific embodiments of this application, the volatile dye is a cucurbitacin dye, and the concentration of the cucurbitacin dye in the cucurbitacin dye solution is 5g / L-25g / L, for example, it can be 5g / L, 7g / L, 10g / L, 12g / L, 15g / L, 17g / L, 20g / L, 22g / L, 25g / L, etc. By limiting the concentration of the cucurbitacin dye solution within the above range, it is possible to further ensure that the cucurbitacin dye solution is uniformly coated on the tail end of the diaphragm body, and to ensure that the formed dye layer has a bright color that can be recognized by the machine.

[0067] According to some specific embodiments of this application, the volatile dye is formaldehyde blue dye, and the concentration of formaldehyde blue dye in the formaldehyde blue dye solution is 5g / L-25g / L, for example, it can be 5g / L, 7g / L, 10g / L, 12g / L, 15g / L, 17g / L, 20g / L, 22g / L, 25g / L, etc. By limiting the concentration of the formaldehyde blue dye solution within the above range, it is possible to further ensure that the formaldehyde blue dye solution is uniformly coated on the tail end of the diaphragm body and ensure that the formed dye layer has a bright color that can be recognized by the machine.

[0068] S200: Assemble a diaphragm with a dye layer as an electrode core;

[0069] In this step, the separator is placed between the positive and negative electrode plates and then assembled (e.g., stacked or wound) to form the electrode core. During assembly, the dye layer formed at the end of the separator serves as an identification feature, reminding relevant personnel to replace the separator material and avoiding misjudgment of the remaining separator length.

[0070] After the separator is assembled, the assembled battery can be baked under the same conditions as the lithium-ion battery manufacturing process.

[0071] S300: The electrode core is subjected to hot pressing and / or light irradiation treatment to allow the volatile dyes in the dye layer to evaporate.

[0072] In the embodiments of this application, the assembled separator is subjected to hot pressing and / or light irradiation treatment to cause the volatile dyes in the dye layer to evaporate, thereby avoiding or reducing the impact of dyes entering the battery system on battery performance and maintaining the stability of the battery system.

[0073] In the embodiments of this application, the temperature of the hot-pressing process is not particularly limited, as long as the volatile dyes in the dye layer can be volatilized. As some preferred embodiments, the temperature of the hot-pressing process is 80°C-150°C. By limiting the temperature of the hot-pressing process within the above range, the volatilization of volatile dyes in the dye layer can be further ensured, thereby further avoiding or reducing the impact of dyes entering the battery system on battery performance and maintaining the stability of the battery system.

[0074] According to the method for preparing the electrode core according to the embodiments of this application, the method uses volatile dyes to print dye on the tail end of the separator body. This serves to identify the tail end of the separator in advance during the assembly of the separator into the electrode core, reminding relevant personnel to replace the separator material and avoiding misjudgment of the remaining separator length. Simultaneously, the volatile dye at the tail end of the separator disappears or weakens after the separator assembly is completed due to heat or light exposure, thereby avoiding or reducing the impact of dye entering the battery system on battery performance and maintaining the stability of the battery system.

[0075] In a third aspect, this application proposes a battery. According to embodiments of this application, the battery includes the separator described in the above embodiments or the electrode core prepared by the electrode core method described in the above embodiments. This avoids or reduces the impact of dye entering the battery system on battery performance, thus maintaining the stability of the battery system.

[0076] Specifically, the specific type of battery mentioned above is not particularly limited; it can be a lithium-ion battery or a sodium-ion battery.

[0077] In a fourth aspect, this application proposes an electrical device. According to an embodiment of this application, the electrical device has the battery described above. Thus, the electrical device possesses all the advantages of a diaphragm, which will not be elaborated further here.

[0078] Specifically, electrical equipment can include lighting elements, display elements, mobile devices, etc., specifically including streetlights, signal lights, insect-killing lamps, electric fans, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Among them, electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.; photovoltaic power generation systems can include large-scale ground photovoltaic power generation systems, distributed photovoltaic power generation and building-integrated photovoltaic power generation systems, etc.

[0079] The embodiments of this application are described in detail below. It should be noted that the embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. In addition, unless otherwise specified, all reagents used in the following embodiments are commercially available or can be synthesized according to the methods described herein or known methods. For reaction conditions not listed, they are also readily available to those skilled in the art.

[0080] Example 1

[0081] This embodiment provides a lithium-ion battery, the preparation method of which is as follows:

[0082] 1) Preparation of positive electrode sheet

[0083] The positive electrode active material lithium iron phosphate, binder polyvinylidene fluoride, and conductive agent acetylene black were mixed at a mass ratio of 95:1:4. A certain amount of N-methylpyrrolidone (NMP) was added, and the mixture was stirred evenly under vacuum to obtain a positive electrode slurry. The positive electrode slurry was uniformly coated onto the positive electrode current collector aluminum foil and dried. Then it was transferred to a vacuum oven and dried at 120°C for 24 hours. Finally, it was rolled and cut to obtain the positive electrode sheet.

[0084] 2) Preparation of negative electrode sheet

[0085] Artificial graphite (anode active material), acetylene black (conductive agent), styrene-butadiene rubber (SBR) (binder), and carboxymethyl cellulose (CMC) (mass ratio 94:2:2:2) were mixed together with a certain amount of deionized water and stirred evenly under vacuum to obtain anode slurry. The anode slurry was then uniformly coated onto copper foil (anode current collector) and dried. It was then transferred to a vacuum oven and dried at 120°C for 24 hours. Finally, the anode sheet was obtained by rolling and cutting.

[0086] 3) Preparation of electrolyte

[0087] In a nitrogen atmosphere glove box with a water content of <1ppm and an oxygen content of <1ppm, ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed in a mass ratio of EC:EMC = 3:5 as a mixed solvent. Then, lithium salt LiPF6 was slowly dissolved in the mixed organic solvent, with the mass percentage of lithium salt LiPF6 being 16%.

[0088] 4) Diaphragm

[0089] PE membranes with a thickness of 12μm are available.

[0090] A methylene blue AZ solution with a concentration of 16.67 g / L is provided. The methylene blue AZ solution is coated onto the tail end of the PE membrane and dried to form a dye layer at the tail end of the PE membrane.

[0091] 5) Assembly of lithium-ion batteries

[0092] The negative electrode, the separator with a dye layer, and the positive electrode are stacked in sequence. The separator after stacking is baked and hot-pressed at 110°C to allow the volatile dyes in the dye layer to evaporate. Next, positive and negative electrode tabs are welded together, and the cells are encapsulated with aluminum-plastic film to obtain the battery cell. After vacuum drying the cell at 80°C for 72 hours, a corresponding electrolyte is injected and the cell is encapsulated. Then, the lithium-ion battery is obtained through steps such as settling, pressurized formation, aging, venting, and capacity testing.

[0093] Example 2

[0094] The preparation method in this embodiment is basically the same as that in Example 1, with the only difference being:

[0095] 4) Provide a 12 g / L methylene blue AZ solution.

[0096] Example 3

[0097] The preparation method in this embodiment is basically the same as that in Example 1, with the only difference being:

[0098] 4) Provide a 20 g / L methylene blue AZ solution.

[0099] Example 4

[0100] The preparation method in this embodiment is basically the same as that in Example 1, with the only difference being:

[0101] 4) Provide a 25 g / L methylene blue AZ solution.

[0102] Example 5

[0103] The preparation method in this embodiment is basically the same as that in Example 1, with the only difference being:

[0104] 4) Replace the 16.67 g / L methylene blue AZ solution with a 16.67 g / L methylene blue 6BX solution;

[0105] 5) The hot pressing temperature is 110℃.

[0106] Example 6

[0107] The preparation method in this embodiment is basically the same as that in Example 1, with the only difference being:

[0108] 4) Replace the 16.67 g / L methylene blue AZ solution with a 16.67 g / L methylene blue 5B solution;

[0109] 5) The hot pressing temperature is 110℃.

[0110] Example 7

[0111] The preparation method in this embodiment is basically the same as that in Example 1, with the only difference being:

[0112] 4) Replace the 16.67 g / L methylene blue AZ solution with a solution containing 13 g / L iodine and 35 g / L potassium iodide;

[0113] 5) The hot pressing temperature is 100℃.

[0114] Example 8

[0115] The preparation method in this embodiment is basically the same as that in Example 1, with the only difference being:

[0116] 4) Replace the 16.67 g / L methylene blue AZ solution with a 200 g / L stannous red G solution;

[0117] 5) The hot pressing temperature is 115℃.

[0118] Example 9

[0119] The preparation method in this embodiment is basically the same as that in Example 8, except that:

[0120] 4) Replace the 200 g / L stannous red G solution with a 50 g / L stannous red G solution.

[0121] Example 10

[0122] The preparation method in this embodiment is basically the same as that in Example 8, except that:

[0123] 4) Replace the 200 g / L stannous red G solution with a 300 g / L stannous red G solution.

[0124] Example 11

[0125] The preparation method in this embodiment is basically the same as that in Example 8, except that:

[0126] 4) Replace the 200 g / L stannous red G solution with a 200 g / L stannous yellow 2G solution;

[0127] 5) The hot pressing temperature is 115℃.

[0128] Example 12

[0129] The preparation method in this embodiment is basically the same as that in Example 8, except that:

[0130] 4) Replace the 200 g / L stannous red G solution with a 200 g / L stannous orange 2G solution;

[0131] 5) The hot pressing temperature is 115℃.

[0132] Example 13

[0133] The preparation method in this embodiment is basically the same as that in Example 8, except that:

[0134] 4) Replace the 200 g / L stannous red G solution with a 200 g / L stannous blue 2R solution;

[0135] 5) The hot pressing temperature is 115℃.

[0136] Example 14

[0137] The preparation method in this embodiment is basically the same as that in Example 8, except that:

[0138] 4) Replace the 200 g / L stannous red G solution with the 200 g / L stannous purple 2R solution;

[0139] 5) The hot pressing temperature is 115℃.

[0140] Example 15

[0141] The preparation method in this embodiment is basically the same as that in Example 8, except that:

[0142] 4) Replace the 200 g / L stannous red G solution with a 200 g / L stannous green 2G solution;

[0143] 5) The hot pressing temperature is 115℃.

[0144] Example 16

[0145] The preparation method in this embodiment is basically the same as that in Example 1, with the only difference being:

[0146] 4) Replace the 16.67 g / L methylene blue AZ solution with a 15 g / L cucurbitacin dye solution;

[0147] 5) The hot pressing temperature is 110℃.

[0148] Example 17

[0149] The preparation method in this embodiment is basically the same as that in Example 1, with the only difference being:

[0150] 4) Replace the 16.67 g / L methylene blue AZ solution with a 15 g / L formaldehyde blue dye solution;

[0151] 5) The hot pressing temperature is 120℃.

[0152] Example 18

[0153] The preparation method in this embodiment is basically the same as that in Example 1, with the only difference being:

[0154] The stacked diaphragms are then subjected to ultraviolet (UV) irradiation to volatilize the methylene blue (AZ) dye in the dye layer. The UV irradiation device must be installed after the end-of-line identification equipment. After irradiation, the diaphragms undergo routine baking and hot-pressing processes.

[0155] Comparative Example 1

[0156] The preparation method of this comparative example differs from that of Example 1 in that:

[0157] 4) The end of the separator was marked using a positive electrode material pigment (the positive electrode slurry in Example 1). The specific process was as follows: Take the positive electrode slurry from Example 1 and dilute it with NMP. The fineness of the slurry was tested using a scraper fineness meter (reading accuracy of 2μm). When the slurry fineness reading was 25μm, the slurry was loaded into a spraying device and sprayed onto the end of the separator. It was then dried to form a dye layer at the end of the PE separator.

[0158] Comparative Example 2

[0159] The preparation method of this comparative example differs from that of Example 1 in that:

[0160] 4) The end of the separator was marked using a negative electrode material pigment (the negative electrode slurry in Example 1). The specific process was as follows: Take the negative electrode slurry from Example 1 and dilute it with deionized water. The fineness of the slurry was tested using a scraper fineness meter (reading accuracy of 2μm). When the slurry fineness reading was 25μm, the slurry was loaded into the spraying equipment and sprayed onto the end of the separator.

[0161] The initial coulombic efficiency, capacity, and cycle performance of the lithium-ion batteries prepared in Examples 1-18 and Comparative Examples 1-2 were tested respectively. The test methods are as follows, and the test results are shown in Table 1.

[0162] Test method:

[0163] First Coulomb efficiency test:

[0164] At room temperature (25°C), the battery prepared above was charged at a constant current of 0.1C to 4.3V, and then charged at a constant voltage until the current was less than 0.025C; then left to stand for 10 minutes, and discharged at a constant current of 0.1C to 3.0V; the first charge capacity and the first discharge capacity of the battery were recorded.

[0165] Initial coulombic efficiency (%) = (first discharge capacity / first charge capacity) × 100%.

[0166] Discharge capacity test:

[0167] 1) Constant current discharge: The battery prepared above is discharged at a constant current of 0.33C until the lower limit voltage of 2.8V is reached;

[0168] 2) Let it sit for 10 minutes;

[0169] 3) Constant current and constant voltage charging: Charge the battery prepared above at a current of 0.33C until the upper limit voltage is 4.2V and the cut-off current is 0.05C;

[0170] 4) Let it sit for 10 minutes;

[0171] 5) Constant current discharge: Discharge the battery prepared above at a current of 0.33C until the lower limit voltage of 3.00V;

[0172] 6) Repeat steps 2)-5) three times, and record the capacity and average voltage of the last step.

[0173] Cyclic performance test:

[0174] 1) Testing equipment: Battery testing cabinet, model Lanqi, constant temperature chamber;

[0175] 2) Testing method:

[0176] The batteries prepared above were subjected to initial RPTs tests at 25±5℃.

[0177] Charging: Charge at a constant current of 1C to 4.1V, then charge at 0.5C to 4.2V, and then charge at a constant current and constant voltage of 0.33C to 4.3V, with a cutoff current of 0.05C;

[0178] Let stand for 10 minutes;

[0179] Discharge: Discharge at a constant current of 0.33C to 2.8V;

[0180] Let stand for 10 minutes;

[0181] The battery prepared above is cycled according to the above process until the capacity retention rate drops to 80% and the number of cycles is reached; an RPT test is performed every 200 cycles.

[0182] Table 1

[0183]

[0184]

[0185] As can be seen from Table 1, compared with Comparative Example 1, the initial coulombic efficiency of the lithium-ion batteries in Examples 1-18 is significantly improved. This shows that using the volatile dye of this application to replace the existing cathode material dyes can significantly improve the initial coulombic efficiency of lithium-ion batteries.

[0186] As can be seen from Table 1, the capacity of the lithium-ion batteries in Examples 1-18 is significantly improved compared with Comparative Example 2. This shows that using the volatile dye of this application to replace the existing negative electrode material dyes can significantly improve the capacity of lithium-ion batteries.

[0187] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0188] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A diaphragm, characterized in that, include: diaphragm body; A dye layer is disposed at the tail end of the diaphragm body, and the dye layer includes volatile dyes.

2. The diaphragm according to claim 1, characterized in that, The volatile dye has an evaporation temperature of 40℃-150℃.

3. The diaphragm according to claim 1, characterized in that, The volatile dyes include at least one of iodine dyes, stannous ester dyes, methylene blue dyes, cucurbitacin dyes, and formaldehyde blue dyes.

4. The diaphragm according to claim 3, characterized in that, The stannous dyes include at least one of stannous yellow, stannous orange, stannous red, stannous blue, stannous violet, and stannous green; And / or, the methylene blue dye includes at least one of methylene blue, methylene blue 5B, methylene blue 6BX and methylene blue AZ.

5. The diaphragm according to claim 4, characterized in that, The stannous yellow includes at least one of stannous yellow 2G and stannous yellow 3G; And / or, the stannous orange includes at least one of stannous orange 2G and stannous orange 3G; And / or, the stannous red includes at least one of stannous red G, stannous red GR, and stannous red 3R; And / or, the stannous blue includes at least one of stannous blue 2R and stannous blue 3R; And / or, the stannous violet includes at least one of stannous violet 2R and stannous violet 3R; And / or, the stannous green includes at least one of stannous green 2G and stannous green 3G.

6. The diaphragm according to any one of claims 1-5, characterized in that, The width of the dye layer is 0.7cm-1.3cm.

7. A method for preparing an electrode core, characterized in that, include: Obtain a diaphragm with a dye layer comprising a volatile dye; The diaphragm with the dye layer is assembled into an electrode core; The electrode core is subjected to hot pressing and / or light irradiation treatment to cause the volatile dyes in the dye layer to evaporate.

8. The method for preparing the electrode core according to claim 7, characterized in that, Obtaining a diaphragm with a dye layer includes: coating the volatile dye solution onto the tail end of the diaphragm body, drying, and forming the dye layer at the tail end of the diaphragm body.

9. The method for preparing the electrode core according to claim 7 or 8, characterized in that, The volatile dye is an iodine dye, and the concentration of the iodine dye in the iodine dye solution is 10 g / L-16 g / L.

10. The method for preparing the electrode core according to claim 7 or 8, characterized in that, The volatile dye is a stannous ester dye, and the concentration of the stannous ester dye in the stannous ester dye solution is 50 g / L-300 g / L.

11. The method for preparing the electrode core according to claim 7 or 8, characterized in that, The volatile dye is methylene blue dye, and the concentration of the methylene blue dye in the methylene blue dye solution is 12g / L-25g / L.

12. The method for preparing the electrode core according to claim 7 or 8, characterized in that, The volatile dye is a cucurbitacin dye, and the concentration of the cucurbitacin dye in the cucurbitacin dye solution is 5 g / L-25 g / L.

13. The method for preparing the electrode core according to claim 7 or 8, characterized in that, The volatile dye is formaldehyde blue dye, and the concentration of formaldehyde blue dye in the formaldehyde blue dye solution is 5 g / L-25 g / L.

14. The method for preparing the electrode core according to any one of claims 7-13, characterized in that, The temperature of the hot pressing treatment is 80℃-150℃.

15. A battery, characterized in that, The battery comprises the separator according to any one of claims 1-6 or the electrode core prepared by the method for preparing the electrode core according to any one of claims 7-14.

16. An electrical appliance, characterized in that, It has the battery as described in claim 15.

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