Diaphragm, method for preparing pole core, battery and electric equipment

Abstract

The invention relates to the field of batteries, and particularly discloses a diaphragm, a method for preparing a pole core, a battery and electric equipment. The dye layer is arranged at the tail end of the diaphragm body, and the dye layer comprises volatile dye. The volatile dye adopted by the invention can be used for printing and dyeing the tail end of the diaphragm body. Moreover, the volatile dye can disappear or weaken due to heating or light irradiation after the diaphragm is assembled, so that the influence on the performance of the battery due to the fact that the dye enters the battery system can be avoided or reduced, and the stability of the battery system is kept.

Description

Technical Field

[0001] The present application belongs to the field of battery technology, and specifically relates to a diaphragm, a method for preparing a pole core, a battery and electrical equipment. Background Art

[0002] During the assembly of lithium-ion batteries (such as lamination or winding), the machine often stops due to unexpected situations, which will cause misjudgment of the remaining diaphragm length, and then lead to waste of incomplete assembly due to insufficient diaphragm length. In order to reduce the waste caused by such situations, the method of spraying positive and negative electrode material dyes on the tail end of the diaphragm is usually adopted, that is, the diaphragm is sprayed and dyed with dyes at a distance from the tail end of the diaphragm, so that the tail end of the diaphragm can be identified in advance during the assembly process, reminding relevant personnel to replace the diaphragm material.

[0003] However, most of the dyes used in the positive and negative electrode materials of lithium-ion battery separators will affect the performance of the battery to varying degrees, causing the battery's electrical performance to become unstable or even suddenly change. Summary of the invention

[0004] The present application aims to solve at least one of the technical problems in the related art to a certain extent. To this end, the purpose of the present application is to propose a diaphragm, a method for preparing a pole core, a battery and an electrical device. The volatile dye used in the present application can not only print and dye the tail end of the diaphragm body. Moreover, the volatile dye can disappear or weaken due to heat or light exposure after the diaphragm is assembled, 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.

[0005] In one aspect of the present application, the present application provides a diaphragm. According to an embodiment of the present application, the diaphragm includes:

[0006] diaphragm body;

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

[0008] According to the diaphragm of the embodiment of the present application, the tail end of the diaphragm body is printed and dyed with a volatile dye, so that the tail end of the diaphragm can be identified in advance during the assembly process, reminding relevant personnel to replace the diaphragm material and avoiding misjudgment of the remaining diaphragm length. At the same time, the volatile dye at the tail end of the diaphragm can disappear or weaken due to heat or light after the diaphragm is assembled, 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.

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

[0010] In some embodiments of the present application, the volatilization temperature of the volatile dye is 40°C-150°C.

[0011] In some embodiments of the present application, the volatile dye includes at least one of an iodine dye, a stannate dye, a methylene blue dye, a citrulline dye, and a formaldehyde blue dye.

[0012] In some embodiments of the present application, the stannite dye includes at least one of stannite yellow, stannite orange, stannite red, stannite blue, stannite violet and stannite 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 the present application, the stannate yellow includes at least one of stannate yellow 2G and stannate yellow 3G; and / or, the stannate orange includes at least one of stannate orange 2G and stannate orange 3G; and / or, the stannate red includes at least one of stannate red G, stannate red GR, and stannate red 3R; and / or, the stannate blue includes at least one of stannate blue 2R and stannate blue 3R; and / or, the stannate violet includes at least one of stannate violet 2R and stannate violet 3R; and / or, the stannate green includes at least one of stannate green 2G and stannate green 3G.

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

[0015] In a second aspect of the present application, the present application proposes a method for preparing a polar core. According to an embodiment of the present application, the method comprises:

[0016] obtaining a membrane with a dye layer, wherein the dye layer includes a volatile dye;

[0017] Assembling the diaphragm with the dye layer as a pole core;

[0018] The pole core is subjected to heat pressing treatment and / or light irradiation treatment so as to volatilize the volatile dye in the dye layer.

[0019] In some embodiments of the present application, obtaining a membrane with a dye layer includes: coating a volatile dye solution on the tail end of the membrane body, drying, and forming the dye layer on the tail end of the membrane body.

[0020] According to the method for preparing the pole core of the embodiment of the present application, the method uses volatile dyes to print and dye the tail end of the diaphragm body, so that in the process of assembling the diaphragm into the pole core, the tail end of the diaphragm can be identified in advance, reminding relevant personnel to replace the diaphragm material to avoid misjudgment of the remaining diaphragm length. At the same time, the volatile dye at the tail end of the diaphragm disappears or weakens due to heat or light after the diaphragm is assembled, 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.

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

[0022] In some embodiments of the present 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 the present application, the volatile dye is a stannate dye, and the concentration of the stannate dye in the stannate dye solution is 50 g / L-300 g / L.

[0024] In some embodiments of the present 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 the present application, the volatile dye is a citrulline dye, and the concentration of the citrulline dye in the citrulline dye solution is 5 g / L-25 g / L.

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

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

[0028] In the third aspect of the present application, the present application proposes a battery. According to an embodiment of the present application, the battery includes the separator described in the above embodiment or the pole core prepared by the method for preparing the pole core described in the above embodiment. In this way, the influence of dye entering the battery system on the battery performance can be avoided or reduced, and the stability of the battery system can be maintained.

[0029] In the fourth aspect of the present application, the present application proposes an electric device. According to an embodiment of the present application, the electric device has a battery as described above. Therefore, the electric device has all the advantages of the battery, which will not be repeated here.

[0030] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0032] Figure 1 This is a flow chart of the method for preparing a pole core according to an embodiment of the present application. DETAILED DESCRIPTION

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

[0034] This application is proposed by the inventor based on the following issues:

[0035] In the related art, most of the dyes used for the separator of lithium-ion batteries are dyes that will enter the battery system with the separator. The introduction of dyes will affect the performance of the battery to varying degrees, resulting in instability of the battery's electrical performance or even sudden changes in performance. For example, positive electrode material dyes used as separator dyes will cause a decrease in the battery's first coulomb efficiency. At the same time, if positive electrode dyes are coated on the negative electrode side, they are also prone to short circuits and lithium precipitation, resulting in reduced battery safety. The introduction of negative electrode materials into the battery system as dyes will cause the battery capacity to decrease; at the same time, if negative electrode materials are coated on one side of the positive electrode separator, lithium precipitation and short circuits are likely to occur, resulting in reduced battery safety. In addition, if the coating thickness is not accurately controlled, the thickness of the battery will increase, and the volume change of the battery during charging and discharging will increase, thereby reducing the battery's life and safety and increasing the risk of battery failure.

[0036] In view of this, in one aspect of the present application, the present application proposes a diaphragm. According to an embodiment of the present application, the diaphragm includes: a diaphragm body; a dye layer, the dye layer is arranged at the tail end of the diaphragm body, and the dye layer includes a volatile dye. Therefore, the volatile dye used in the present application can not only print and dye the tail end of the diaphragm body. Moreover, the volatile dye can disappear or weaken due to heat or light exposure after the diaphragm is assembled, 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.

[0037] The following is a detailed description of the principle by which the diaphragm proposed in this application can achieve the above beneficial effects:

[0038] The present application uses volatile dyes to print and dye the tail end of the diaphragm body, so that during the assembly process (such as lamination or winding), the tail end of the diaphragm can be identified in advance, reminding relevant personnel to replace the diaphragm material and avoiding misjudgment of the remaining diaphragm length. At the same time, the volatile dye at the tail end of the diaphragm can disappear or weaken due to heat or light after the diaphragm is assembled, 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.

[0039] The dye of the present application can volatilize after being heated at high temperature or under light irradiation, and is a volatile dye. Volatile dye is a special dye whose molecular structure will quickly change from solid to gas under heating conditions or light irradiation conditions without dissolving or chemical reaction.

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

[0041] According to some specific embodiments of the present application, the volatilization temperature of the above-mentioned volatile dye is 40°C-150°C, thereby ensuring 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 some further specific embodiments of the present application, the volatile dye includes at least one of iodine dye, stannate dye, methylene blue dye, citrulline dye and formaldehyde blue dye, so that the above-mentioned types of volatile dyes can be used to print and dye the tail end of the diaphragm body. Moreover, the above-mentioned types of volatile dyes can disappear or weaken due to heat or light exposure after the diaphragm is assembled, 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. Preferably, at least one of stannate dye, methylene blue dye, citrulline dye and formaldehyde blue dye is used, and more preferably, methylene blue dye is used.

[0043] In the embodiment of the present application, iodine dye can select conventional iodine dye or high concentration iodine dye available on the market, and the concentration of dye is appropriately adjusted by adding solvent, and then placed in a spraying device with good sealing performance, and the storage temperature should not exceed 40 ° C. The preparation of iodine dye can also be carried out voluntarily, and the preparation process is: take a certain amount of iodine and potassium iodide, dissolve 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 spraying device with good sealing performance, and the spraying effect of the diaphragm test iodine dye solution that needs to be sprayed is taken to ensure that the color is bright and can be recognized by the machine. If the color is not bright enough, it can be considered to reduce the amount of deionized water and improve the concentration of iodine dye.

[0044] Iodine dye usage environment: Set the diaphragm production and storage environment temperature to ≤45°C, and try to keep it below 40°C. Use a spray device filled with iodine dye solution to spray and dye the tail end of the diaphragm. Let it dry naturally and store the diaphragm at room temperature.

[0045] Volatilization conditions of iodine dye: The environment for assembling the diaphragm must be strictly controlled according to the battery-level dew point. After assembly, the assembled electrode is subjected to hot pressing treatment (the sublimation of iodine dye can be achieved when the temperature is greater than 45°C). There is no need to set the temperature and drying time separately in order to volatilize the iodine dye.

[0046] It should be noted that during the assembly (eg lamination or winding) process, the separator is disposed between the positive electrode sheet and the negative electrode sheet, and then lamination or winding is performed.

[0047] In the embodiment of the present application, the temperature at which the methylene blue dye begins to volatilize is about 100° C.-120° C.

[0048] In the embodiments of the present 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. The above types of methylene blue dyes can be used to dye the membrane. Methylene blue AZ suitable for dyeing cotton fibers is preferably used to dye the membrane.

[0049] The following describes the use of methylene blue dye using methylene blue AZ as an example:

[0050] In the embodiment of the present application, the above-mentioned methylene blue AZ dye solution can directly purchase the standard solution, but the concentration of the standard solution is low, and the dyeing effect sprayed on the diaphragm is not obvious, so the dye solution can be prepared by purchasing methylene blue AZ powder. The preparation process is: take a certain amount of methylene blue AZ powder and bake it in an oven for 1h~10h, the baking temperature is ≤100℃, and the methylene blue AZ powder is obtained, dissolved in deionized water, stirred for 0~60min, and a methylene blue AZ solution with a concentration of 12g / L-21g / L is obtained. Then the prepared methylene blue AZ solution is transferred to the prepared spraying device for storage and standby use, with a service life of 28 days and a storage temperature of ≤40℃. In order to ensure the effect after the dye is sprayed, take the diaphragm to be sprayed for spraying experiments, observe the color state of the diaphragm after spraying, whether it can be recognized by the machine, and adjust the appropriate concentration before the actual diaphragm spraying production application.

[0051] In the embodiments of the present application, the use environment of methylene blue dye is as follows: the production environment temperature of the diaphragm is set to ≤40°C, and the diaphragm after spraying is stored away from light. At the same time, the ambient temperature of the diaphragm during assembly needs to be ≤40°C, avoiding direct sunlight to ensure that the methylene blue dye does not fade when the machine is identifying. During the baking stage after assembly, the temperature setting can be carried out according to the battery production process.

[0052] Volatilization conditions of methylene blue dye: After the diaphragm is assembled, the assembled pole piece is baked and hot pressed. The baking conditions are the production process conditions of lithium-ion batteries, and the hot pressing temperature must be ≥100°C so that the methylene blue dye on the diaphragm can volatilize due to high temperature. Alternatively, after the assembly is completed, an ultraviolet lamp can be used to irradiate the identified diaphragm. The methylene blue dye will volatilize under the condition of light, which can avoid introducing too much methylene blue dye into the battery system and affecting the electrical performance of the battery system.

[0053] In the embodiments of the present application, the specific types of the above-mentioned stannate dyes are not particularly limited. As some specific examples, the above-mentioned stannate dyes include at least one of stannate yellow, stannate orange, stannate red, stannate blue, stannate purple and stannate green. Among them, stannate yellow includes stannate yellow 2G, stannate yellow 3G, etc. Stannate orange includes stannate orange 2G, stannate orange 3G, etc. Stannate red includes stannate red G, stannate red GR, stannate red 3R, etc. Stannate blue includes stannate blue 2R, stannate blue 3R, etc. Stannate purple includes stannate purple 2R, stannate purple 3R, etc. Stannate green includes stannate green 2G, stannate green 3G, etc. The above-mentioned types of stannate dyes can all disappear or weaken due to heat after the diaphragm is assembled, 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.

[0054] The following describes the use of stannous ester dyes using stannous ester red G as an example:

[0055] Preparation and storage of stannous ester red G dye: Select a stannous ester red G dye solution with a mass concentration of 50g / L-300g / L and place it in a spraying device with good sealing. In order to ensure the effect of dye spraying, take the diaphragm to be sprayed for spraying experiments, observe the color state of the diaphragm after spraying, whether it can be recognized by the machine, and adjust the appropriate concentration before actual diaphragm spraying production application.

[0056] Use environment of stannous ester red G dye: The use and storage environment temperature must be ≤100℃.

[0057] The volatilization conditions of stannous ester red G dye: After the diaphragm is assembled, the assembled electrode needs to be baked and hot-pressed. The baking conditions can be set according to the design process of the lithium-ion battery, but the hot-pressing conditions must be set at 150°C. After hot-pressing, the stannous ester red G dye on the diaphragm can be volatilized.

[0058] According to some specific embodiments of the present application, the width of the dye layer (i.e., the width along the stacking direction or the winding direction) is 0.7cm-1.3cm. The dye layer of a certain width can further play a role in 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 the second aspect of the present application, the present application proposes a method for preparing a core. According to the embodiments of the present application, referring to the attached Figure 1 , including the following steps:

[0060] S100: obtaining a membrane with a dye layer, wherein the dye layer includes a volatile dye;

[0061] In this step, a diaphragm with a dye layer is obtained, and the dye layer includes a volatile dye, so that during the process of assembling the diaphragm with the dye layer into a pole core (for example, during the lamination or winding process of the diaphragm), the tail end of the diaphragm can be identified in advance, reminding relevant personnel to replace the diaphragm material and avoiding misjudgment of the remaining diaphragm length.

[0062] According to some specific embodiments of the present application, the above-mentioned method of obtaining the membrane with a dye layer includes: coating a volatile dye solution on the tail end of the membrane body, drying, and forming a dye layer at the tail end of the membrane body.

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

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

[0065] According to some other specific embodiments of the present application, 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, 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 can be further ensured that the methylene blue dye solution is evenly coated on the tail end of the diaphragm body, and it can be ensured that the formed dye layer has a bright color and can be recognized by the machine.

[0066] According to some other specific embodiments of the present application, the volatile dye is a citrulline dye, and the concentration of the citrulline dye in the citrulline 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 citrulline dye solution within the above range, it can be further ensured that the citrulline dye solution is evenly coated on the tail end of the diaphragm body, and it can be ensured that the formed dye layer has a bright color and can be recognized by the machine.

[0067] According to some other specific embodiments of the present 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 can be further ensured that the formaldehyde blue dye solution is evenly coated on the tail end of the diaphragm body, and it can be ensured that the formed dye layer has a bright color and can be recognized by the machine.

[0068] S200: Assembling the diaphragm with the dye layer as a pole core;

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

[0070] After the diaphragm is assembled, the assembled battery can be baked, and the baking conditions are the production process conditions of lithium-ion batteries.

[0071] S300: performing heat pressing treatment and / or light irradiation treatment on the electrode core so as to volatilize the volatile dye in the dye layer.

[0072] In an embodiment of the present application, the assembled diaphragm is subjected to heat pressing and / or light irradiation treatment to volatilize the volatile dye in the dye layer, 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.

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

[0074] According to the method for preparing the pole core of the embodiment of the present application, the method uses volatile dyes to print and dye the tail end of the diaphragm body, so that in the process of assembling the diaphragm into the pole core, the tail end of the diaphragm can be identified in advance, reminding relevant personnel to replace the diaphragm material to avoid misjudgment of the remaining diaphragm length. At the same time, the volatile dye at the tail end of the diaphragm disappears or weakens due to heat or light after the diaphragm is assembled, 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.

[0075] In the third aspect of the present application, the present application proposes a battery. According to an embodiment of the present application, the battery includes the diaphragm described in the above embodiment or the pole core prepared by the pole core method described in the above embodiment. In this way, the influence of dye entering the battery system on the battery performance can be avoided or reduced, and the stability of the battery system can be maintained.

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

[0077] In the fourth aspect of the present application, the present application proposes an electric device. According to an embodiment of the present application, the electric device has a battery as described above. Therefore, the electric device has all the advantages of the diaphragm, which will not be repeated here.

[0078] Specifically, electrical equipment may include lighting elements, display elements, mobile devices, etc., and may specifically include street lights, signal indicators, insect killer lamps, electric fans, electric toys, electric tools, battery vehicles, electric vehicles, ships, spacecraft, etc., among which electric toys may include fixed or mobile electric toys, for example, game consoles, electric car toys, electric ship toys and electric airplane toys, etc., and spacecraft may include airplanes, rockets, space shuttles and spacecraft, etc.; photovoltaic power generation systems may include large-scale ground photovoltaic power generation systems, distributed photovoltaic power generation and building integrated photovoltaic power generation systems, etc.

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

[0080] Example 1

[0081] This embodiment provides a lithium ion battery, and the preparation method thereof is as follows:

[0082] 1) Preparation of positive electrode

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

[0084] 2) Preparation of negative electrode

[0085] The negative electrode active material artificial graphite, the conductive agent acetylene black, the binder styrene butadiene rubber (SBR) and carboxymethyl cellulose (CMC) are mixed in a mass ratio of 94:2:2:2, a certain amount of deionized water is added, and the mixture is stirred evenly under the action of a vacuum mixer to obtain a negative electrode slurry; the negative electrode slurry is evenly coated on the negative electrode current collector copper foil and dried; then the mixture is transferred to a vacuum oven and dried at 120°C for 24 hours, and then rolled and cut to obtain a negative electrode sheet.

[0086] 3) Preparation of electrolyte

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

[0088] 4) Diaphragm

[0089] Provide PE separator with a thickness of 12μm.

[0090] A methylene blue AZ solution having a concentration of 16.67 g / L is provided, and the methylene blue AZ solution is coated on the tail end of the PE separator and dried to form a dye layer on the tail end of the PE separator.

[0091] 5) Assembly of lithium-ion batteries

[0092] The negative electrode sheet, the separator with the dye layer, and the positive electrode sheet are stacked in sequence, and the stacked separator is baked and hot-pressed at a temperature of 110°C to volatilize the volatile dye in the dye layer. Then the positive and negative poles are welded, and the battery cell is encapsulated with an aluminum-plastic film. The battery cell is vacuum-dried at 80°C for 72 hours, and then the corresponding prepared electrolyte is injected and packaged. Then, a lithium-ion battery is obtained through the steps of standing, pressurized formation, aging, exhaust, and capacity separation.

[0093] Example 2

[0094] The preparation method of this embodiment is basically the same as that of embodiment 1, except that:

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

[0096] Example 3

[0097] The preparation method of this embodiment is basically the same as that of embodiment 1, except that:

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

[0099] Example 4

[0100] The preparation method of this embodiment is basically the same as that of embodiment 1, except that:

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

[0102] Example 5

[0103] The preparation method of this embodiment is basically the same as that of embodiment 1, except that:

[0104] 4) replacing 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°C.

[0106] Example 6

[0107] The preparation method of this embodiment is basically the same as that of embodiment 1, except that:

[0108] 4) replacing 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°C.

[0110] Example 7

[0111] The preparation method of this embodiment is basically the same as that of embodiment 1, except that:

[0112] 4) replacing 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°C.

[0114] Example 8

[0115] The preparation method of this embodiment is basically the same as that of embodiment 1, except that:

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

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

[0118] Example 9

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

[0120] 4) The 200 g / L stannite red G solution was replaced with a 50 g / L stannite red G solution.

[0121] Example 10

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

[0123] 4) The 200 g / L stannite red G solution was replaced with a 300 g / L stannite red G solution.

[0124] Embodiment 11

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

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

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

[0128] Example 12

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

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

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

[0132] Embodiment 13

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

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

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

[0136] Embodiment 14

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

[0138] 4) replacing the 200 g / L stannate red G solution with 200 g / L stannate violet 2R solution;

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

[0140] Embodiment 15

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

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

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

[0144] Example 16

[0145] The preparation method of this embodiment is basically the same as that of embodiment 1, except that:

[0146] 4) replacing the methylene blue AZ solution with a concentration of 16.67 g / L with a citrulline dye solution with a concentration of 15 g / L;

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

[0148] Embodiment 17

[0149] The preparation method of this embodiment is basically the same as that of embodiment 1, except that:

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

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

[0152] Embodiment 18

[0153] The preparation method of this embodiment is basically the same as that of embodiment 1, except that:

[0154] The laminated diaphragm is irradiated with ultraviolet light to volatilize the methylene blue AZ dye in the dye layer. The ultraviolet irradiation device must be installed after the tail end identification device. After irradiation, the diaphragm is baked and hot pressed as usual.

[0155] Comparative Example 1

[0156] The difference between the preparation method of this comparative example and that of Example 1 is that:

[0157] 4) The positive electrode material pigment (positive electrode slurry in Example 1) is used to mark the tail end of the separator. The specific process is as follows: take the positive electrode slurry in Example 1 and add NMP to dilute it. Use a scraper fineness meter (reading accuracy of 2 μm) to test the fineness of the slurry. When the slurry fineness reading is 25 μm, the slurry is loaded into the spraying equipment and sprayed on the tail end of the separator, and dried to form a dye layer at the tail end of the PE separator.

[0158] Comparative Example 2

[0159] The difference between the preparation method of this comparative example and that of Example 1 is that:

[0160] 4) Use negative electrode material pigment (negative electrode slurry in Example 1) to mark the tail end of the separator. The specific process is as follows: Take the negative electrode slurry in Example 1 and add deionized water to dilute it. Use a scraper fineness meter (reading accuracy of 2 μm) to test the fineness of the slurry. When the slurry fineness reading is 25 μm, load the slurry into the spraying equipment and spray it on the tail 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. The test results are shown in Table 1.

[0162] Test method:

[0163] First coulombic efficiency test:

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

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

[0166] Discharge capacity test:

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

[0168] 2) Leave for 10 minutes;

[0169] 3) Constant current and constant voltage charging: The battery prepared above is charged at a current of 0.33C to an upper voltage of 4.2V and a cut-off current of 0.05C;

[0170] 4) Leave for 10 minutes;

[0171] 5) Constant current discharge: The battery prepared above is discharged at a current of 0.33C to a lower limit voltage of 3.00V;

[0172] 6) Repeat 2)-5) three times and record the last divided capacity and average voltage.

[0173] Cycle performance test:

[0174] 1) Test equipment: battery testing cabinet, model Lanqi, constant temperature box;

[0175] 2) Test method:

[0176] The batteries prepared above were subjected to initial RPTs testing at 25±5°C;

[0177] Charging: 1C constant current to 4.1V, then 0.5C to 4.2V, then 0.33C constant current and constant voltage to 4.3V, cut-off current 0.05C;

[0178] Let stand for 10 minutes;

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

[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% of the cut-off number of cycles; an RPTs test is performed every 200 cycles.

[0182] Table 1

[0183]

[0184]

[0185] It can be seen from Table 1 that compared with Comparative Example 1, the first coulombic efficiency of the lithium ion batteries of Examples 1-18 is significantly improved. It can be seen that using the volatile dye of the present application to replace the existing positive electrode material dye can significantly improve the first coulombic efficiency of the lithium ion battery.

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

[0187] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0188] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

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

2. The diaphragm according to claim 1, characterized in that The volatilization temperature of the volatile dye is 40°C-150°C.

3. The diaphragm according to claim 1, characterized in that The volatile dye includes at least one of an iodine dye, a stannate dye, a methylene blue dye, a citrulline dye, and a formaldehyde blue dye.

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

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

7. A method for preparing a core, characterized in that: include: obtaining a membrane with a dye layer, wherein the dye layer includes a volatile dye; Assembling the diaphragm with the dye layer as a pole core; The pole core is subjected to heat pressing treatment and / or light irradiation treatment so as to volatilize the volatile dye in the dye layer.

8. The method for preparing a pole core according to claim 7, characterized in that: The method of obtaining the membrane with the dye layer comprises: coating the volatile dye solution on the tail end of the membrane body, drying, and forming the dye layer on the tail end of the membrane body.

9. The method for preparing a pole 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 a pole core according to claim 7 or 8, characterized in that: The volatile dye is a stannate dye, and the concentration of the stannate dye in the stannate dye solution is 50 g / L-300 g / L.

11. The method for preparing a pole 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 12 g / L-25 g / L.

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

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

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

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

16. An electrical equipment, characterized in that: A battery according to claim 15.

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