Diaphragm, method of manufacturing, battery, and electric device

Abstract

The application discloses a diaphragm and a preparation method thereof, a battery and an electric device. The diaphragm comprises a base film and a rubber coating layer located on at least one side surface of the base film; the rubber coating layer comprises a dye; and the color of the dye is different from that of the base film. The diaphragm and the preparation method thereof, the diaphragm and the rubber coating layer have a large color difference, facilitating detection of the rubber coating area of the diaphragm in a unit area, and the detection can be performed through a CCD detection device, which is beneficial to controlling the uniformity of the rubber coating layer of the diaphragm, thereby guaranteeing the electrochemical performance of the battery and the bonding performance of the rubber coating layer.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to a separator and a preparation method thereof, a battery and an electric device. BACKGROUND

[0002] Lithium batteries, as a new type of secondary battery, have the advantages of high energy density and long cycle life. With the continuous expansion of application range, lithium batteries are widely used in portable electronic devices, energy storage devices and electric vehicles, and especially in the context of the rapid development of the new energy industry, the application of lithium batteries in electric vehicles is more and more extensive.

[0003] As an important component of lithium batteries, the separator plays a key role in preventing the positive and negative electrodes from directly contacting and causing short circuits, and has an important influence on the safety of lithium batteries. In view of the problem of the adhesion of the separator to the electrode sheet, the main solution at present is to coat a glue layer on one side or both sides of the separator. This glue layer can effectively improve the adhesion of the separator, and at the same time has good wettability with the electrolyte.

[0004] However, there are many problems in the existing glue coating technology. The traditional glue-coated separator cannot detect the glue-coated area of the separator per unit area. Taking water-based PVDF (Polyvinylidene Fluoride) glue coating technology as an example, since the glue-coated area of the separator per unit area cannot be effectively detected, it is difficult to control the uniformity of the coating, which may affect the electrochemical performance of the battery and the adhesion of the glue layer. SUMMARY

[0005] The present application aims to at least solve one of the technical problems in the related art. To this end, one object of the present application is to provide a separator and a preparation method thereof, a battery and an electric device. The separator and the preparation method thereof of the present application have a large color difference between the glue layer and the base film, which facilitates the detection of the glue-coated area of the separator per unit area, and can be detected by a CCD (Charge-Coupled Device) detection device, which is conducive to controlling the uniformity of the glue-coated layer of the separator, thereby ensuring the electrochemical performance of the battery and the adhesion of the glue layer.

[0006] The first aspect of the present application provides a separator. According to the embodiments of the present application, the separator comprises a base film and a glue layer located on at least one side surface of the base film; the glue layer comprises a dye; the color of the dye is different from the color of the base film.

[0007] The application adds dye in the glue coating layer, the color of the dye is different from the color of the base film, the color contrast of the glue coating layer and the base film is high, the glue coating area is obviously distinguished from the non-coating area, the coating recognition degree is high, the recognition error is small, so that the glue coating area of the diaphragm in unit area can be realized by CCD online all and equipment full detection under the existing conditions, and the unevenly coated diaphragm is intercepted. In addition, the application can be applied to glue coating layers of various thicknesses.

[0008] The second aspect of the application provides a preparation method of a diaphragm, comprising the steps of:

[0009] Mixing the dye with the glue slurry to obtain a mixed slurry;

[0010] Coating the mixed slurry on the base film to form a glue coating layer to obtain a diaphragm; the color of the dye is different from the color of the base film.

[0011] The preparation method of the diaphragm provided by the application is a preparation method of a glue-coated diaphragm, which does not change the existing preparation process of glue coating, directly adds dye in the glue slurry, and has simple preparation method and is beneficial to industrial production.

[0012] The application adds dye in the glue coating layer, the color of the dye is different from the color of the base film, the color contrast of the glue coating layer and the base film is high, the glue coating area is obviously distinguished from the non-coating area, the coating recognition degree is high, the recognition error is small, so that the glue coating area of the diaphragm in unit area can be realized by CCD online all and equipment full detection under the existing conditions, and the unevenly coated diaphragm is intercepted. In addition, the application can be applied to glue coating layers of various thicknesses.

[0013] The third aspect of the application provides a battery comprising the diaphragm or the diaphragm prepared by the preparation method.

[0014] The battery provided by the application has the above-mentioned diaphragm, and the glue coating area of the diaphragm in unit area can be detected during the preparation process, the uniformity of the glue coating layer is controlled, and the electrochemical performance of the battery and the adhesion of the glue coating layer are improved.

[0015] The fourth aspect of the application provides an electrical equipment comprising the battery.

[0016] The electrical equipment provided by the application has the above-mentioned battery, and the battery is used for providing power supply and has high safety performance.

[0017] Additional aspects and advantages of the application will be given in part in the following description, part will become obvious from the following description, or will be understood by the practice of the application. DETAILED DESCRIPTION

[0018] Embodiments of the present application are described in detail below. The embodiments described below are exemplary only and are not intended to be limiting of the present application.

[0019] It should be noted that the terms "first", "second" are used only for descriptive purposes and are not to be construed as indicating or implying relative importance or an indicated number of technical features. Thus, features defined with "first", "second" can explicitly or implicitly include one or more of the features. Further, in the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise specified.

[0020] The endpoints of the ranges and any values disclosed in the present application are not limited to the precise values recited as the exact dimensions are not critical to the present application. Any numerical range recited is intended to include all sub-ranges subsumed therein. For a numerical range recited as being "between A and B", for example, the intended scope is all numbers between (and including) the recited numbers, not just numbers strictly between A and B. Furthermore, all ranges disclosed are inclusive of the endpoints.

[0021] In the present application, the term "comprising" or "including" is an open term, i.e. including the contents indicated in the present application, but not excluding other contents.

[0022] The separator, as an important component of the lithium battery, plays a key role in preventing the positive and negative electrodes from directly contacting and causing short circuit, and has an important influence on the safety of the lithium battery. In view of the problem of the adhesion of the separator to the pole piece, the main solution at present is to coat a glue layer on one side or both sides of the separator. This glue layer can effectively improve the adhesion of the separator, and has good wettability with the electrolyte.

[0023] At present, for the reasons of improving the wettability of the separator with the electrolyte, enhancing the thermal stability of the separator, and improving the ion migration rate, etc., the glue layer on the surface of the separator is usually not 100% full coverage, and the glue coating area of the separator per unit area is less than 100%. The traditional glue-coated separator cannot detect the glue coating area of the separator per unit area. Taking the water-based PVDF (Polyvinylidene Fluoride) glue coating technology as an example, due to the inability to detect the glue coating area of the separator per unit area for effective detection, the glue coating amount of the glue-coated separator is too much or too little. Too much leads to an increase in the probability of hole blocking of the separator, and a decrease in the electrical performance of the battery; and too little leads to insufficient adhesion of the glue-coated separator, and fails to achieve the purpose of adhesion of the glue-coated separator. The CCD detection equipment is further upgraded. Since the glue layer and the separator are usually white, transparent or close to transparent, the contrast difference between the two is low, and full online detection cannot be achieved.

[0024] To this end, the first aspect of the embodiments of the present application provides a diaphragm, comprising a base film and a glue coating layer located on at least one side surface of the base film; the glue coating layer comprises a dye; the color of the dye is different from the color of the base film.

[0025] The embodiments of the present application add the dye in the glue coating layer, the color contrast between the glue coating layer and the base film is high, the glue coating area is obviously distinguished from the non-coating area, the coating recognition degree is high, the recognition error is small, so that the glue coating area of the diaphragm in a unit area can be detected by the existing CCD online and equipment, and the non-uniformly coated diaphragm is intercepted. In addition, the present application can be applied to glue coating layers of various thicknesses.

[0026] According to the embodiments of the present application, the raw material of the glue coating layer comprises a hot melt adhesive, and the starting volatilization temperature of the dye is less than or equal to the melting temperature of the hot melt adhesive.

[0027] In the embodiments of the present application, the starting volatilization temperature of the dye added to the glue coating layer meets the above condition, in addition to improving the color contrast between the glue coating layer and the base film, the dye volatilizes under heat during the hot melting treatment of the raw material of the glue coating layer, and finally only a small amount of dye component remains in the glue coating layer, which can greatly reduce the influence of the addition of the dye on the battery performance and is beneficial to maintaining the stability of the battery system. In the specific implementation, the dye with a suitable starting volatilization temperature can be selected based on the raw material composition of the glue coating layer, the preparation process of the battery, and the like.

[0028] According to the embodiments of the present application, the dye comprises at least one of formaldehyde blue, chymotrypsin and methylene blue.

[0029] In some embodiments, at least one of formaldehyde blue, chymotrypsin and methylene blue is selected and added to the glue coating layer, which can improve the color contrast between the glue coating layer and the base film, realize the detection of the glue coating area of the diaphragm in a unit area, and realize the full online detection by the CCD detection equipment.

[0030] In some embodiments, at least one of formaldehyde blue, chymotrypsin and methylene blue is selected and added to the glue coating layer, these dyes have a relatively low starting volatilization temperature, and the dye disappears or weakens under heat during the hot melting treatment of the raw material of the glue coating layer, so that the stability of the diaphragm in the battery can be maintained and the influence of the dye on the battery performance can be reduced.

[0031] Methyl violet: Methyl violet is a volatile dye commonly used in fields such as biological staining, histology and microscopy. The starting volatilization temperature is about 150℃-180℃, and the completion volatilization temperature is about 200℃-230℃.

[0032] Cresol Red: Cresol Red is a volatile dye that changes color in acid-base, and is widely used in biochemical analysis in chemical laboratories. The temperature at which the volatilization begins is about 130°C to 150°C, and the temperature at which the volatilization is completed is about 180°C.

[0033] According to the embodiments of the present application, the color difference between the base film and the rubber coating layer is 0.2 NBS to 15 NBS.

[0034] In the preparation process of the glue layer, the dye is added. In the preparation process of the glue-coated separator, there is a large color difference between the base film and the glue layer (unhardened) coated with the glue slurry. The glue-coated area of the separator per unit area can be detected, and the uniformity of the glue coating can be effectively controlled. After the glue layer is hardened, although the dye may be lost, there is still an excess amount or residue, and at this time the base film and the glue layer still have a certain color difference. In specific examples, the color difference between the base film and the glue layer is 0.2NBS, 0.3NBS, 0.4NBS, 0.5NBS, 0.6NBS, 0.7NBS, 0.8NBS, 0.9NBS, 1NBS, 1.1NBS, 1.2NBS, 1.3NBS, 1.4NBS, 1.5NBS, 1.6NBS, 1.7NBS, 1.8NBS, 1.9NBS, 2NBS, 2.1NBS, 2.2NBS, 2.5NBS, 2.6NBS, 2.7NBS, 2.8NBS, 2.9NBS, 3NBS, 3.1NBS, 3.2NBS, 3.3NBS, 3.4NBS, 3.5NBS, 3.6NBS, 3.7NBS, 3.8NBS, 3.9NBS, 4NBS, 4.1NBS, 4.2NBS, 4.3NBS, 4.4NBS, 4.5NBS, 4.6NBS, 4.7NBS, 4.8NBS, 4.9NBS, 5NBS, 5.1NBS, 5.2NBS, 5.3NBS, 5.4NBS, 5.5NBS, 5.6NBS, 5.7NBS, 5.8NBS, 5.9NBS, 6NBS, 6.1NBS, 6.2NBS, 6.3NBS, 6.4NBS, 6.5NBS, 6.6NBS, 6.7NBS, 6.8NBS, 6.9NBS, 7NBS, 7.1NBS, 7.2NBS, 7.3NBS, 7.4NBS, 7.5NBS, 7.6NBS, 7.7NBS, 7.8NBS, 7.9NBS, 8NBS, 8.1NBS, 8.2NBS, 8.3NBS, 8.4NBS, 8.5NBS, 8.6NBS, 8.7NBS, 8.8NBS, 8.9NBS, 9NBS, 9.1NBS, 9.2NBS, 9.3NBS, 9.4NBS, 9.5NBS, 9.6NBS, 9.7NBS, 9.8NBS, 9.9NBS, 10NBS, 10.1NBS, 10.2NBS, 10.3NBS, 10.4NBS, 10.5NBS, 10.6NBS, 10.7NBS, 10.8NBS, 10.9NBS, 11NBS, 11.1NBS, 11.2NBS, 11.3NBS, 11.4NBS, 11.5NBS, 11.6NBS, 11.7NBS, 11.8NBS, 11.9NBS, 12NBS, 12.1NBS, 12.2NBS, 12.4NBS, 12.5NBS, 12.6NBS, 12.7NBS, 12.8NBS, 12.9NBS, 13NBS, 13.1NBS, 13.2NBS, 13.3NBS, 13.4NBS, 13.5NBS, 13.6NBS, 13.7NBS, 13.8NBS, 13.9NBS, 14NBS or 15NBS, or any other value between 0.2NBS and 15NBS.

[0035] Further, the color difference between the base film and the coating layer is 0.2NBS to 8NBS.

[0036] According to the embodiments of the present application, the color difference between the base film and the coating layer is 2NBS to 15NBS before the coating layer is cured. The dye is added in the process of preparing the coating layer. There is a large color difference between the base film and the coating layer (not cured) in the process of preparing the coating membrane. The coating area of the membrane per unit area can be detected, and the uniformity of the coating can be effectively controlled. In the curing process of the coating layer, the dye may be lost. If a volatile dye is selected to be added to the coating layer, the coating layer will volatilize in the preparation process, and most of the dye will volatilize from the coating layer in a short time, reducing the impact on the performance of the battery. Finally, there may be a small amount of dye remaining in the coating layer, and the color difference between the base film and the coating layer can still be detected. Therefore, the color difference between the base film and the coating layer is 0.2NBS to 8NBS after the coating layer is cured. Further, the color difference between the base film and the coating layer is 0.2NBS to 3NBS.

[0037] According to the embodiments of the present application, the coating area of the coating layer on the surface of the base film is 5% to 95% of the area of the base film.

[0038] At present, the coating layer on the surface of the membrane is usually not 100% full coverage for the reasons of improving the wettability of the membrane and electrolyte, enhancing the thermal stability of the membrane, improving the ion migration rate, etc. The coating area of the membrane per unit area is less than 100%. The traditional coated membrane cannot detect the coating area of the membrane per unit area, but the present application can improve the color contrast between the coating layer and the base film by adding a dye with a color different from that of the base film, so as to realize the detection of the coating area of the membrane per unit area. Based on the coverage rate of the coating layer at present, the present application can be applied to the case that the coating area of the coating layer on the surface of the base film is 5% to 95% of the area of the base film. In specific examples, the coating area of the coating layer on the surface of the base film is 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% of the area of the base film, etc.

[0039] According to the embodiment of the present application, the coating area of the adhesive layer on the surface of the base film is 10% to 50% of the area of the base film.

[0040] Currently, the lower the coating area of the adhesive layer on the surface of the base film is relative to the area of the base film, the more difficult it is to identify, detect and control the uniformity of the coating. However, by adding a dye in the adhesive layer that is different in color from the base film, the color contrast between the adhesive layer and the base film can be improved. When the coating area on the surface of the base film is small, the small adhesive particles randomly distributed are light and thin, the color contrast is low, and the coverage detection accuracy is low. However, the method of the present application can effectively detect the coating area of the diaphragm per unit area when the coating area on the surface of the base film is less than 50% of the area of the base film, which is of great significance to the preparation of the adhesive diaphragm and the improvement of the battery performance.

[0041] In specific examples, the coating area of the adhesive layer on the surface of the base film is 10%, 12%, 14%, 15%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50% or the like of the area of the base film.

[0042] Further, the coating area of the adhesive layer on the surface of the base film is 15% of the area of the base film.

[0043] According to the embodiment of the present application, the adhesive layer further comprises adhesive particles, and the adhesive particles comprise at least one of polyvinylidene fluoride adhesive particles, polyvinyl alcohol adhesive particles, polymethyl methacrylate adhesive particles and AFL adhesive particles.

[0044] In the embodiment of the present application, a hot melt adhesive can be used as the raw material of the adhesive layer, and the hot melt adhesive comprises adhesive particles. In the present application, the type of adhesive particles used in the adhesive layer is not limited, as long as it meets the requirements of the battery diaphragm. The adhesive particles for the adhesive layer known in the art can be used.

[0045] In specific examples, the adhesive particles of the present application can comprise at least one of polyvinylidene fluoride (PVDF) adhesive particles, polyvinyl alcohol (PVA) adhesive particles, polymethyl methacrylate (PMMA) adhesive particles and AFL adhesive particles.

[0046] The AFL adhesive particles are "acrylic, polyacrylic modified adhesive particles", such as modified acrylic adhesive particles or polyacrylic modified adhesive particles.

[0047] According to the embodiment of the present application, the dye is soluble in a solvent or insoluble in a solvent.

[0048] The solubility of the dye added to the adhesive layer in the embodiment of the present application is not limited. The dye can be soluble in a solvent (such as water or an organic solvent) or insoluble in a solvent.

[0049] Further, the dye is insoluble in the solvent or has a low solubility in the solvent.

[0050] In the embodiments of the present application, the dye with low solubility or insolubility is added to the sizing paste, and the dye exists in the sizing paste in a granular form. In the later solvent removal process, the solvent is volatilized, and pores are formed in the sizing layer after volatilization, which is beneficial to the air permeability and the lithium ion channel, and reduces the probability of sizing layer hole blocking.

[0051] The second aspect of the embodiments of the present application provides a preparation method of the separator, including the steps of:

[0052] The dye is mixed with the sizing paste to obtain a mixed paste;

[0053] The mixed paste is coated on the base film to form a sizing layer, and the separator is obtained. The color of the dye is different from the color of the base film.

[0054] The preparation method of the separator provided in the embodiments of the present application is a preparation method of a sizing separator, which does not change the existing preparation process of sizing, directly adds the dye to the sizing paste, and has a simple preparation method and is beneficial to industrial production.

[0055] In the embodiments of the present application, the dye is added to the sizing layer, the color of the dye is different from the color of the base film, the color contrast between the sizing layer and the base film is high, the sizing area is obviously distinguished from the non-spraying area, the coating recognition degree is high, the recognition error is small, and thus the sizing area of the separator per unit area can be detected by the existing equipment, and the non-uniformly sprayed separator can be intercepted. In addition, the present application can be applied to sizing layers with various thicknesses.

[0056] According to the embodiments of the present application, the dye satisfies at least one of the following conditions:

[0057] The raw material of the sizing layer includes a hot melt adhesive, and the starting volatilization temperature of the dye is less than or equal to the melting temperature of the hot melt adhesive.

[0058] The dye includes at least one of formaldehyde blue, guafoak and methylene blue.

[0059] In the embodiments of the present application, the starting volatilization temperature of the dye added to the sizing layer satisfies the above condition. In addition to improving the color contrast between the sizing layer and the base film, the dye is volatilized by heat during the hot melting treatment of the raw material of the sizing layer, and only a small amount of dye component is finally left in the sizing layer, which can greatly reduce the influence of the addition of the dye on the battery performance and is beneficial to maintaining the stability of the battery system. In the specific implementation, the dye with a suitable starting volatilization temperature according to the present application can be selected based on the raw material composition of the sizing layer, the preparation process of the battery and the like.

[0060] In some embodiments, at least one of formaldehyde blue, chrysophanol and methylene blue is selected to be added to the coating layer, which can improve the color contrast between the coating layer and the base film, realize the detection of the coating area of the separator per unit area, and realize full online detection through a CCD detection device.

[0061] In some embodiments, at least one of formaldehyde blue, chrysophanol and methylene blue is selected to be added to the coating layer, which has a relatively low initial volatilization temperature, and the dye disappears or weakens under heat during the heat melting treatment of the raw material of the coating layer, so that the stability of the separator in the battery can be maintained, and the influence of the dye on the battery performance can be reduced.

[0062] According to the embodiments of the present application, the preparation method further comprises: the step of coating the mixed slurry on the base film to form the coating layer comprises: performing heat melting treatment after the mixed slurry is coated on the base film.

[0063] In the method for preparing the coated separator, heat melting treatment is needed after the coating slurry is coated on the base film, so as to realize solidification and finally form the coating layer.

[0064] If the dye is a volatile dye, and the initial volatilization temperature of the dye is less than or equal to the melting temperature of the hot melt adhesive, the dye will volatilize during the heat melting treatment of the raw material of the coating layer, so that the stability of the separator in the battery can be maintained, and the influence of the dye on the battery performance can be reduced.

[0065] In the process of using the separator to prepare the battery, the coated separator is wound into the pole core, the pole core enters the baking process in the middle stage of the preparation of the battery, and the dye on the separator volatilizes after being baked at high temperature, so that the influence of the dye on the battery performance is reduced.

[0066] According to the embodiments of the present application, the coating area of the mixed slurry on the surface of the base film is 5% to 95% of the area of the base film.

[0067] Currently, for the reasons of improving the wettability of the separator and electrolyte, enhancing the thermal stability of the separator, improving the ion migration rate, etc., the glue coating layer on the surface of the separator is usually not 100% full coverage, the glue coating area of the separator per unit area is less than 100%, the traditional glue coating separator cannot detect the glue coating area of the separator per unit area, but the present application can improve the color contrast between the glue coating layer and the base film by adding a dye in the glue coating layer, thereby realizing the detection of the glue coating area of the separator per unit area. Based on the coverage rate of the glue coating layer at present, the present application can be applied to the case that the coating area of the glue coating layer on the surface of the base film is 5% to 95% of the area of the base film. In specific examples, the coating area of the glue coating layer on the surface of the base film is 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% and the like of the area of the base film.

[0068] According to the embodiments of the present application, the coating area of the glue coating layer on the surface of the base film is 10% to 50% of the area of the base film. In specific examples, the coating area of the glue coating layer on the surface of the base film is 10%, 12%, 14%, 15%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50% and the like of the area of the base film. Further, the coating area of the glue coating layer on the surface of the base film is 15% of the area of the base film.

[0069] According to the embodiments of the present application, the added amount of the dye accounts for less than 3% of the mass of the glue slurry.

[0070] In the embodiments of the present application, the more the dye added in the glue slurry, the greater the color contrast between the glue coating layer and the base film, but it may affect the electrochemical performance of the battery separator, reduce the electrochemical performance of the battery, and increase the preparation cost. In addition, the glue amount has a strong correlation with the color depth.

[0071] In the embodiments of the present application, the added amount of the dye added to the glue slurry meets the above conditions, which is beneficial to balance the color contrast between the glue coating layer and the base film, the battery performance and the preparation cost and other aspects of the demand, and realizes the effective detection of the glue coating area of the separator per unit area. In specific examples, the added amount of the dye accounts for less than 3%, less than 2.8%, less than 2.6%, less than 2.4%, less than 2.2%, less than 2.0%, less than 1.8%, less than 1.6%, less than 1.4%, less than 1.2%, less than 1%, less than 0.8%, less than 0.6%, less than 0.4%, less than 0.2%, less than 0.1%, less than 0.08%, less than 0.06%, less than 0.04%, less than 0.02%, less than 0.01%, less than 0.005% and the like of the mass of the glue slurry.

[0072] According to the embodiment of the present application, the dye is added in an amount of 0.01% to 1% of the mass of the glue coating slurry.

[0073] In the embodiment of the present application, the dye is added in an amount of 0.01% to 1% of the mass of the glue coating slurry, which can effectively balance the color contrast of the glue coating layer and the base film, the battery performance, and the preparation cost and other aspects of the demand, realize the effective detection of the glue coating area of the separator per unit area, and is beneficial to improve the electrochemical performance of the battery and protect the bonding performance of the glue coating layer. In specific examples, the dye is added in an amount of 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1% of the mass of the glue coating slurry, etc.

[0074] According to the embodiment of the present application, the preparation method also satisfies at least one of the following:

[0075] The glue coating slurry includes glue particles and a solvent; the glue particles include at least one of polyvinylidene fluoride glue particles, polyvinyl alcohol glue particles, polymethyl methacrylate glue particles, and AFL glue particles; and the solvent includes water or an organic solvent.

[0076] The material of the base film includes at least one of polyolefin, polyvinylidene fluoride, aramid, cellulose, and polyimide.

[0077] In the present application, the type of glue particles used in the glue coating layer is not limited and can meet the demand of the battery separator, and the glue particles for the glue coating layer known in the art can be used. The material of the base film is not limited and the material of the base film known in the art can be used.

[0078] In specific examples, the glue particles of the present application can include at least one of polyvinylidene fluoride (PVDF) glue particles, polyvinyl alcohol (PVA) glue particles, polymethyl methacrylate (PMMA) glue particles, and AFL glue particles.

[0079] The AFL glue particles are "acrylic, polyacrylic modified glue particles", such as modified acrylic glue particles or polyacrylic modified glue particles.

[0080] The material of the base film includes at least one of polyolefin, polyvinylidene fluoride, aramid, cellulose, and polyimide, and in specific examples, such as at least one of polyethylene, polypropylene, polyvinylidene fluoride, aramid, cellulose, and polyimide, etc.

[0081] According to the embodiment of the present application, the organic solvent includes at least one of acetone, N-methyl pyrrolidone (NMP), n-hexane, dimethylformamide (DMF), dimethylacetamide (DMAC), and dimethyl sulfoxide (DMSO).

[0082] According to the embodiments of the present application, other additives are further included in the glue slurry, and the other additives include at least one of a dispersant, a wetting agent and a binder.

[0083] The dispersant, the wetting agent and the binder can be selected based on the additives commonly known in the art for the glue layer of the separator.

[0084] Further, the dispersant includes an organic dispersant and / or an inorganic dispersant.

[0085] Further, the organic dispersant includes, but is not limited to, at least one of aliphatic amides, triethylhexyl phosphate, sodium dodecyl sulfate, methyl amyl alcohol, cellulose derivatives, polyacrylamide, gum and fatty acid polyethylene glycol esters.

[0086] Further, the inorganic dispersant includes, but is not limited to, at least one of silicates and alkali metal phosphates. The alkali metal phosphates include, but are not limited to, at least one of sodium tripolyphosphate, sodium hexametaphosphate and sodium pyrophosphate.

[0087] Further, the wetting agent includes, but is not limited to, at least one of anionic and non-ionic surfactants. The wetting agent mainly solves the problem of excessive surface tension of the slurry, facilitates coating on the base film to form a lithium battery separator, and can also improve the adhesion between the slurry and the separator.

[0088] Further, the binder includes, but is not limited to, an acrylic binder.

[0089] According to the embodiments of the present application, the raw materials of the slurry include glue particles, a dispersant, a wetting agent, a binder and water; and the mass ratio of the raw materials of the slurry to the dye satisfies:

[0090] The mass ratio of the glue particles, the dispersant, the wetting agent, the binder, water, and the dye is 1:(0.05-0.1):(0.005-0.009):(0.1-0.5):(2-15):(0.05-1).

[0091] The composition formula of the water-based glue coating paste provided in the embodiments of the present application meets the above requirements. By using the water-based glue coating technology, a glue coating layer with a relatively large color contrast with a base film can be obtained, which facilitates detection of the coating area of the separator per unit area. During preparation, CCD detection equipment can be used for online full detection, and non-uniformly coated separators can be intercepted, thereby improving the coating uniformity and the electrochemical performance of the battery and the adhesion of the glue coating layer. In specific examples, the mass ratio of the glue particles, the dispersing agent, the wetting agent, the binder, water, and the dye is 1:(0.05-0.1):(0.005-0.009):(0.1-0.5):(2-15):0.05, 1:(0.05-0.1):(0.005-0.009):(0.1-0.5):(2-15):0.08, 1:(0.05-0.1):(0.005-0.009):(0.1-0.5):(2-15):0.1, 1:(0.05-0.1):(0.005-0.009):(0.1-0.5):(2-15):0.2, 1:(0.05-0.1):(0.005-0.009):(0.1-0.5):(2-15):0.3, 1:(0.05-0.1):(0.005-0.009):(0.1-0.5):(2-15):0.4, 1:(0.05-0.1):(0.005-0.009):(0.1-0.5):(2-15):0.5, 1:(0.05-0.1):(0.005-0.009):(0.1-0.5):(2-15):0.6, 1:(0.05-0.1):(0.005-0.009):(0.1-0.5):(2-15):0.7, 1:(0.05-0.1):(0.005-0.009):(0.1-0.5):(2-15):0.8, 1:(0.05-0.1):(0.005-0.009):(0.1-0.5):(2-15):0.9, 1:(0.05-0.1):(0.005-0.009):(0.1-0.5):(2-15):1, and the like.

[0092] Further, the mass ratio of the glue particles, the dispersing agent, the wetting agent, the binder, water, and the dye is 1:0.08:0.007:0.3:10:0.5.

[0093] The third aspect of the embodiments of the present application provides a battery comprising the above-mentioned separator or the separator obtained by the above-mentioned preparation method.

[0094] The battery provided in the embodiments of the present application has the above-mentioned separator, and the coating area of the separator per unit area can be easily detected during preparation, the uniformity of the glue coating layer can be controlled, and the electrochemical performance of the battery and the adhesion of the glue coating layer can be improved.

[0095] The separator is arranged between the positive electrode sheet and the negative electrode sheet, mainly to prevent short circuit between the positive electrode and the negative electrode, and meanwhile to allow ions to pass through.

[0096] According to the embodiments of the present application, the battery further comprises a positive electrode sheet, a negative electrode sheet and an electrolyte.

[0097] During the charging and discharging of the battery, active ions are embedded and extracted between the positive electrode sheet and the negative electrode sheet. The electrolyte plays a role of conducting ions between the positive electrode sheet and the negative electrode sheet. The separator is arranged between the positive electrode sheet and the negative electrode sheet, mainly to prevent short circuit between the positive electrode and the negative electrode, and meanwhile to allow ions to pass through.

[0098] According to the embodiments of the present application, the positive electrode sheet comprises a positive electrode current collector and a positive electrode active material layer arranged on at least one side surface of the positive electrode current collector, and the positive electrode active material layer comprises a positive electrode active material. The raw materials of the positive electrode current collector and the positive electrode active material layer (including the positive electrode active material) can be materials commonly used in batteries.

[0099] According to the embodiments of the present application, the negative electrode sheet comprises a negative electrode current collector and a negative electrode active material layer arranged on at least one side surface of the negative electrode current collector, and the negative electrode active material layer comprises a negative electrode active material. Alternatively, the negative electrode sheet can be a lithium metal sheet. The raw materials of the negative electrode current collector and the negative electrode active material layer (including the negative electrode active material) can be materials commonly used in batteries.

[0100] According to the embodiments of the present application, the electrolyte can be an electrolyte commonly used in the art.

[0101] The fourth aspect of the embodiments of the present application provides a power consuming device comprising the battery described above.

[0102] The power consuming device provided by the embodiments of the present application has the battery described above, and the battery is used to provide power supply, and has high safety and long service life.

[0103] The power consuming device can include a mobile device (such as a mobile phone, a notebook computer, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship and a satellite, an energy storage system, etc., but is not limited thereto.

[0104] The device as another embodiment can be a mobile phone, a tablet computer, a notebook computer, etc. The device usually requires thinning, and can use a battery monomer as a power supply.

[0105] It should be noted that the features and advantages described above for the separator of the first aspect and the second aspect of the present application also apply to the battery of the third aspect and the power consuming device of the fourth aspect of the present application, which will not be described herein again.

[0106] The scheme of the present application will be explained below in conjunction with examples. Those skilled in the art will understand that the examples below are only for illustration of the present application and should not be regarded as limiting the scope of the present application. If no specific technique or condition is specified in the examples, the technique or condition described in the literature in the art or according to the product manual is used. If no manufacturer of the reagent or instrument is specified, it is a conventional product that can be obtained commercially.

[0107] Example 1

[0108] 1. Preparation of positive electrode sheet

[0109] After stirring and mixing the positive electrode active material lithium iron phosphate, the conductive agent conductive carbon black, the binder polyvinylidene fluoride (PVDF), and the solvent N-methyl pyrrolidone (NMP) in a mass ratio of 100:8:2.5:60, a positive electrode slurry is obtained. The positive electrode slurry is coated on both sides of the surface of the positive electrode current collector aluminum foil, and after drying, rolling, and sheeting, a positive electrode sheet is obtained.

[0110] 2. Preparation of negative electrode sheet

[0111] After stirring and mixing the negative electrode active material graphite, the butadiene-styrene rubber (SBR), the carboxymethyl cellulose (CMC), the conductive graphite, the N-methyl pyrrolidone (NMP), and the water in a mass ratio of 100:3:1.5:1:2:115, a negative electrode slurry is obtained. The negative electrode slurry is coated on both sides of the surface of the negative electrode current collector copper foil, and after drying, rolling, and sheeting, a negative electrode sheet is obtained.

[0112] 3. Preparation of electrolyte

[0113] Electrolyte (the electrolyte is composed of 13wt% LiPF6, 26wt% ethylene carbonate (EC), and 61wt% diethyl carbonate (DEC))

[0114] 4. Preparation of separator

[0115] The mass ratio of the colloidal particles (polyvinylidene fluoride (PVDF) colloidal particles), the dispersant (vinyl bis-stearamide), the wetting agent (sodium dodecyl sulfate), the binder (methyl acrylate), water, and the dye (methylene blue dye) is 1:0.08:0.007:0.3:10:0.5, and a slurry is prepared by mixing. The slurry is coated on one layer of the polypropylene separator by water-based spraying, the coverage is 25%, and a colored coated separator is formed.

[0116] 5. Preparation of lithium ion battery

[0117] The negative electrode sheet, the separator and the positive electrode sheet prepared above are placed in sequence, and then rolled to obtain a battery core. The battery core is placed in an outer packaging foil, and then the battery is baked at 120℃ for 10h. Electrolyte (consisting of 13wt% LiPF6, 26wt% EC and 61wt% DEC) is injected, and formation is carried out under a restraint pressure of 0.3MPa to obtain a lithium ion battery.

[0118] Example 2-3

[0119] Example 2 uses the method of Example 1, except that guaiacol is used instead of methylene blue in Example 1.

[0120] Example 3 uses the method of Example 1, except that formaldehyde blue is used instead of methylene blue in Example 1.

[0121] Example 4-6

[0122] Example 4 uses the method of Example 1, except that the mass ratio of colloidal particles, dispersant, wetting agent, binder, water and dye is 1:0.08:0.007:0.3:10:0.05.

[0123] Example 5 uses the method of Example 1, except that the mass ratio of colloidal particles, dispersant, wetting agent, binder, water and dye is 1:0.08:0.007:0.3:10:0.1.

[0124] Example 6 uses the method of Example 1, except that the mass ratio of colloidal particles, dispersant, wetting agent, binder, water and dye is 1:0.08:0.007:0.3:10:1.

[0125] Example 7-9

[0126] Example 7 uses the method of Example 1, except that the coating area of the slurry on the surface of the base film accounts for 5% of the area of the base film.

[0127] Example 8 uses the method of Example 1, except that the coating area of the slurry on the surface of the base film accounts for 50% of the area of the base film.

[0128] Example 9 uses the method of Example 1, except that the coating area of the slurry on the surface of the base film accounts for 95% of the area of the base film.

[0129] Example 10

[0130] Example 10 uses the method of Example 1, except that the material of the base film is replaced by aramid.

[0131] Example 11

[0132] Example 11 uses the method of Example 1, except that the drying temperature is replaced by 80℃.

[0133] Comparative Example 1

[0134] The method of Example 1 was adopted, except that no dye was added to the glue slurry in the preparation of the separator.

[0135] Performance test

[0136] I. Test method:

[0137] 1. Color difference: The samples provided by the examples and comparative examples were taken as test samples, and a color difference meter was used to measure, and the specific steps were as follows:

[0138] (1) Start the device: First, turn on the color difference meter, press the power button, and wait for the self-checking to complete.

[0139] (2) Select the calibration mode: Switch to the calibration mode, calibrate the white standard on the blank plate, and then calibrate the black standard.

[0140] (3) Select the measurement mode: Select the color measurement mode in the device, select the sample to be measured, and place it on the test table.

[0141] (4) Set the conditions: Measure the tester from the vertical direction of the sample.

[0142] (5) Measurement: Press the measurement button to measure the color, and record the data ΔE.

[0143] II. Performance test results:

[0144] 1. Color difference test results.

[0145] The color difference test results of the samples provided by the examples and comparative examples are shown in Table 1.

[0146] From Table 1, it can be seen that in the process of preparing the separator of the battery provided by the scheme of the present application, by adding dye in the glue layer, the color of the dye is different from the color of the base film, the color contrast between the glue layer and the base film is high, the color difference is large, the glue-coated area is obviously distinguished from the non-coated area, the coating recognition degree is high, the recognition error is small, so that the glue-coated area of the separator per unit area can be fully detected by CCD online under the existing conditions, and the non-uniformly coated separator is intercepted.

[0147] Table 1 Color difference test results

[0148] Sample ΔE(NBS) before drying ΔE(NBS) after drying Example 1 6.27 0.30 Example 2 6.30 3.0 Example 3 6.77 2.2 Example 4 3.10 0.21 Example 5 4.93 0.23 Example 6 7.98 0.42 Example 7 3.24 0.22 Example 8 7.24 0.61 Example 9 10.34 1.34 Example 10 6.32 0.33 Example 11 6.27 5.98 Comparative Example 1 0.11 0.11

[0149] Although the embodiments of the present application have been shown and described above, it is understood that the above-described embodiments are exemplary and are not to be construed as limiting the present application, and that changes, modifications, substitutions and variations can be made by those skilled in the art without departing from the scope of the present application.

Claims

1. A diaphragm, characterized by The base film and the adhesive layer on at least one side of the base film; The adhesive layer comprises a dye; The color of the dye is different from the color of the base film, The raw material of the adhesive layer comprises a hot-melt adhesive, and the starting volatilization temperature of the dye is less than or equal to the melting temperature of the hot-melt adhesive, The step of forming the adhesive layer comprises: after the raw material of the adhesive layer is coated on the base film, a hot melting treatment is performed, and the dye is volatilized by heat during the hot melting treatment.

2. The separator according to claim 1, characterized in that The dye comprises at least one of formaldehyde blue, chymotrypsin and methylene blue.

3. The separator according to claim 1 or 2, characterized in that The color difference between the base film and the adhesive layer is 0.2 NBS-15 NBS.

4. The separator according to any one of claims 1 to 3, characterized in that The coating area of the adhesive layer on the surface of the base film is 5%-95% of the area of the base film.

5. The diaphragm of claim 3 or 4, wherein, The coating area of the adhesive layer on the surface of the base film is 10%-50% of the area of the base film.

6. The separator according to any one of claims 3 to 5, characterized in that The adhesive layer comprises adhesive particles, and the adhesive particles comprise at least one of polyvinylidene fluoride adhesive particles, polyvinyl alcohol adhesive particles, polymethyl methacrylate adhesive particles and AFL adhesive particles.

7. A method of producing a diaphragm, characterized by, The method comprises the steps of: Mixing a dye with an adhesive slurry to obtain a mixed slurry; Coating the mixed slurry on a base film to form an adhesive layer, thereby obtaining a separator; the color of the dye is different from the color of the base film, The raw material of the adhesive layer comprises a hot-melt adhesive, and the starting volatilization temperature of the dye is less than or equal to the melting temperature of the hot-melt adhesive, The step of coating the mixed slurry on the base film to form the adhesive layer comprises: after the mixed slurry is coated on the base film, a hot melting treatment is performed, and the dye is volatilized by heat during the hot melting treatment.

8. The method of claim 7, wherein the membrane is prepared by a method comprising: The dye comprises at least one of formaldehyde blue, chymotrypsin and methylene blue.

9. The method of claim 7 or 8, wherein the membrane is prepared by a method comprising the steps of: The coating area of the mixed slurry on the surface of the base film is 5%-95% of the area of the base film.

10. The method of claim 7 to 9, wherein the membrane is prepared by a method comprising the steps of: The added amount of the dye accounts for less than 3% of the mass of the adhesive slurry.

11. The method of claim 7 to 10, wherein the membrane is prepared by a method comprising the steps of: The added amount of the dye accounts for 0.01%-1% of the mass of the adhesive slurry.

12. The method of claim 7 to 11, wherein the membrane is prepared by a method comprising the steps of: At least one of the following is also met: The adhesive slurry comprises adhesive particles and a solvent; the adhesive particles comprise at least one of polyvinylidene fluoride adhesive particles, polyvinyl alcohol adhesive particles, polymethyl methacrylate adhesive particles and AFL adhesive particles; and the solvent comprises water or an organic solvent. The material of the base film comprises at least one of polyolefin, polyvinylidene fluoride, aramid, cellulose and polyimide.

13. The method of claim 7 to 12, characterized in that The raw material of the slurry comprises adhesive particles, a dispersing agent, a wetting agent, an adhesive and water; and the mass ratio of the raw material of the slurry to the dye meets: The mass ratio of the adhesive particles, the dispersing agent, the wetting agent, the adhesive, water and the dye is 1:(0.05-0.1):(0.005-0.009):(0.1-0.5):(2-15):(0.05-1).

14. A battery, characterized by The separator of any one of claims 1-6 or the separator obtained by the preparation method of any one of claims 7-13.

15. An electrical device, characterized by The battery of claim 14.