A high-liquid-storage high-adhesion performance coated separator, a preparation method and application thereof

Abstract

This invention discloses a high-liquid-storage-performance coated separator, its preparation method, and its application, belonging to the field of battery separator technology. The coated separator includes a base membrane and a coating disposed on at least one surface of the base membrane; the coating contains a first polymer and a second polymer; wherein the first polymer consists of secondary particles formed by the agglomeration of primary particles, with an average particle size of 10 μm to 30 μm and a specific surface area of ​​8 m². 2 / g~25m 2 The polymer has an elastic modulus of 9MPa~20MPa; the average particle size of the second polymer is 0.4μm~1μm, and the glass transition temperature of the second polymer is ≤80℃. The above-mentioned coated separator can improve the adhesion, liquid retention rate, and stress buffering capacity of the separator in the C-corner region of a square wound cell, thereby increasing the cell production yield, reducing the risk of lithium plating, and extending the cell cycle life.

Description

Technical Field

[0001] This invention relates to the field of battery separator technology, and more specifically, to a coated separator with high liquid storage and high adhesion performance, its preparation method, and its application. Background Technology

[0002] Due to geometric constraints (such as small radius of curvature and multiple layers of materials), the C-corner region of square wound battery cells is prone to significant stress concentration during winding, pre-compression curing, and charge-discharge cycling. This leads to micro-damage to the separator, shedding of active material from the electrode, and micro-cracks in the current collector, which in turn obstructs the lithium-ion transport path, inducing lithium plating in the C-corner region and severely affecting cell safety and cycle life. Furthermore, the compressive characteristics of traditional coatings under pressure are uncontrollable, making it difficult to buffer the instantaneous stress impact in the C-corner region. The adhesion strength between the coating and the electrode is also insufficient, easily leading to interlayer slippage, exacerbating shear stress concentration, increasing interfacial contact impedance, and causing uneven electrolyte wetting, further deteriorating the cell's electrochemical performance.

[0003] In view of this, the present invention is proposed. Summary of the Invention

[0004] The purpose of this invention is to provide a coated diaphragm with high liquid storage and high adhesion performance, its preparation method and application, so as to solve or improve the above-mentioned technical problems.

[0005] This invention can be implemented as follows: In a first aspect, the present invention provides a high liquid storage and high adhesion performance coated diaphragm, the high liquid storage and high adhesion performance coated diaphragm comprising a base film and a coating disposed on at least one side surface of the base film; The coating contains a first polymer and a second polymer; The first polymer consists of secondary particles formed by the agglomeration of primary particles. The average particle size of the first polymer is 10 μm to 30 μm, and its specific surface area is 8 m². 2 / g~25m 2 / g, with an elastic modulus of 9MPa~20MPa; The average particle size of the second polymer is 0.4 μm to 1 μm, and the glass transition temperature of the second polymer is ≤80℃.

[0006] In an optional embodiment, the average particle size of the primary particles in the first polymer is 100 nm to 800 nm.

[0007] In an optional embodiment, the first polymer is polymerized from monomer A, which includes at least one of vinylidene fluoride, methyl methacrylate, ethyl methacrylate, methacrylonitrile, butyl methacrylate, styrene, acrylonitrile, methacrylonitrile, and 2-ethylhexyl methacrylate.

[0008] In an optional embodiment, the average particle size variation coefficient of the second polymer is CV, where CV ≤ 5%.

[0009] In an optional embodiment, the gelation rate of the second polymer is 80% to 98%.

[0010] In an optional embodiment, the second polymer is polymerized from monomer B, which includes at least one of methyl methacrylate, ethyl methacrylate, methacrylonitrile, butyl methacrylate, styrene, acrylonitrile, methacrylonitrile, and 2-ethylhexyl methacrylate.

[0011] In an optional embodiment, the coating comprises 68% to 88% of a first polymer and 10% to 25% of a second polymer by weight percentage.

[0012] In an optional embodiment, the coating further contains additives, the additives comprising 2% to 8% by mass in the coating, and / or the additives include at least one of styrene-butadiene rubber, polyacrylate, polyacrylamide, polyacrylonitrile, and epoxy resin.

[0013] In an optional embodiment, the high liquid storage and high adhesion coated diaphragm also has at least one of the following characteristics: Feature 1: The areal density of the coating is 0.4 g / m³. 2 ~1.2g / m 2 ; Feature 2: The high liquid storage and high adhesion performance of the coated diaphragm results in a compression ratio of X1 under hot pressing at 1 MPa, 85℃, and 1 hour, where 20% ≤ X1 ≤ 55%. Feature 3: The high liquid storage and high adhesion performance of the coated diaphragm results in a compression ratio of X2 under hot pressing at 2MPa, 85℃, and 1h, where 40%≤X2≤70%. Feature 4: High liquid retention and high adhesion performance. The liquid retention rate of the coated diaphragm after hot pressing at 1MPa, 85℃ and 1h is ER1, 130%≤ER1≤270%; Feature 5: High liquid retention and high adhesion performance. The liquid retention rate of the coated diaphragm after hot pressing at 2MPa, 85℃ and 1h is ER2, 100%≤ER2≤160%; Feature 6: High liquid storage and high adhesion performance. The dry pressure adhesion force between the coated diaphragm and the electrode sheet under hot pressing at 1MPa, 85℃ and 85s is F1, 2N / m ≤F1≤15N / m; Feature 7: High liquid storage and high adhesion performance. The dry pressure adhesion force between the coated diaphragm and the electrode sheet under hot pressing at 2MPa, 85℃ and 85s is F2, 2.5N / m ≤F2≤20N / m; Feature 8: High liquid storage and high adhesion performance. The wet pressure adhesion force between the coated diaphragm and the electrode sheet under 1MPa conditions is F3, 4N / m≤F3≤26N / m; Feature 9: High liquid storage and high adhesion performance. The wet pressure adhesion between the coated diaphragm and the electrode sheet under 2MPa conditions is F4, 5N / m≤F4≤38N / m.

[0014] In an optional implementation, X2 < 2X1.

[0015] In an optional implementation, F2 > F1.

[0016] In a second aspect, the present invention provides a method for preparing a coated diaphragm with high liquid storage and high adhesion performance as described in any of the foregoing embodiments, comprising the following steps: coating a slurry containing at least a first polymer and a second polymer onto at least one side surface of a base membrane, and drying.

[0017] Thirdly, the present invention provides a battery cell comprising a coated separator with high liquid storage and high adhesion performance according to any of the foregoing embodiments.

[0018] Fourthly, the present invention provides a battery comprising the cell of the foregoing embodiments.

[0019] The beneficial effects of this invention include: The high liquid storage and high adhesion performance coated diaphragm provided by the present invention includes a base membrane and a coating disposed on at least one surface of the base membrane; the coating contains a first polymer and a second polymer; the first polymer is a secondary particle formed by the agglomeration of primary particles, the average particle size of the first polymer is 10μm~30μm, and the specific surface area is 8m². 2 / g~25m 2 / g, with an elastic modulus of 9MPa~20MPa; the average particle size of the second polymer is 0.4μm~1μm, and the glass transition temperature of the second polymer is ≤80℃.

[0020] The high liquid storage and high adhesion performance coated separator that meets the above characteristics has a suitable compression ratio and adhesion, which can effectively improve the fit, liquid retention rate and stress buffering capacity of the C-corner separator of square wound cells, thereby improving the cell production qualification rate, reducing the risk of lithium plating in cells and extending the cycle life of cells. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 A schematic diagram of the cross-section of the coated diaphragm with high liquid storage and high adhesion performance provided by the present invention; Figure 2 A schematic diagram of the high liquid storage and high adhesion performance coating on the diaphragm surface provided by the present invention; Figure 3 This is a schematic diagram of the cross-section of a square wound battery cell. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0024] The following is a detailed description of the high liquid storage and high adhesion performance coated diaphragm provided by the present invention, its preparation method, and its application.

[0025] This invention provides a coated diaphragm with high liquid storage and high adhesion performance. Please refer to... Figure 1 and Figure 2 The coated diaphragm includes a base membrane and a coating disposed on at least one side of the base membrane.

[0026] The aforementioned coating is an organic polymer coating, which, by mass percentage, may comprise 68% to 88% of a first polymer and 10% to 25% of a second polymer. The mass percentage of the first polymer may be 68%, 70%, 72%, 75%, 78%, 80%, 82%, 85%, or 88%, or other values ​​within the range of 68% to 88%. The mass percentage of the second polymer may be 10%, 12%, 15%, 18%, 20%, 22%, or 25%, or other values ​​within the range of 10% to 25%.

[0027] The first polymer primarily serves to provide support and achieve good compressibility, while the second polymer mainly provides adhesion. If the proportion of the first polymer is too low, it hinders the formation of a stable porous support structure in the coating, leading to poor compressive resilience and easy compaction and pore blockage, thus affecting ion transport efficiency and the overall compressibility of the diaphragm. If the proportion of the first polymer is too high, there are insufficient bonding sites in the coating, resulting in decreased adhesion between the coating and the base film and electrodes, easily causing powder shedding and detachment, affecting cell assembly and cycle stability. If the proportion of the second polymer is too low, it fails to provide sufficient adhesion, resulting in insufficient adhesion between the coating and the base film, easily causing powder shedding and detachment, and insufficient adhesion strength to the electrode sheets, affecting cell assembly stability and cycle reliability. If the proportion of the second polymer is too high, it excessively fills the pores and encapsulates the first polymer support structure, leading to decreased coating porosity, increased ion transport resistance, and a softer coating prone to thermal compaction deformation, which is detrimental to maintaining good compressive resilience and pore structure stability.

[0028] The first polymer is a secondary particle formed by the agglomeration of primary particles. By adopting the form of a secondary particle first polymer, there are pores between the secondary particles, thereby giving the first polymer a porous structure, so as to provide suitable compression performance for coating the diaphragm.

[0029] In some optional embodiments, the average particle size of the first polymer can be 10μm to 30μm, such as 10μm, 15μm, 20μm, 25μm, or 30μm, or other values ​​within the range of 10μm to 30μm. In some more typical embodiments, the average particle size of the first polymer is 11.8μm to 26.4μm. If the average particle size of the first polymer is less than 10μm, the effective pores inside the coating are too small and easily filled and blocked by the second polymer, resulting in increased ion transport resistance. At the same time, the supporting skeleton structure is weak, and the compression resilience and structural stability are poor. If the average particle size of the first polymer is greater than 30μm, it is not conducive to the surface smoothness of the coating, the overall thickness uniformity of the coating decreases, and problems such as local protrusions and particle accumulation are likely to occur. The adhesion to the electrode is poor, and the coating cohesion is reduced, making it easy for powder to fall off and affect the assembly and safety stability of the battery cell.

[0030] In some optional embodiments, the average particle size of the primary particles in the first polymer can be 100 nm to 800 nm, such as 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, or 800 nm, or other values ​​within the range of 100 nm to 800 nm. In some more typical embodiments, the average particle size of the primary particles in the first polymer is 180 nm to 320 nm.

[0031] In some alternative embodiments, the specific surface area of ​​the first polymer can be 8 m². 2 / g~25m 2 / g, such as 8m 2 / g, 10m 2 / g, 15m 2 / g、20m 2 / g or 25m 2 / g, etc., can also be 8m 2 / g~25m 2 Other values ​​within the range of / g. If the specific surface area of ​​the first polymer is less than 8m². 2 / g, which is not conducive to improving the overall porosity of the coating and the connectivity of ion transport channels, and will also reduce the wetting contact area with the second polymer and electrolyte, resulting in poor coating wettability and low ion transport efficiency. If the specific surface area of ​​the first polymer is greater than 25m², 2A specific surface area of ​​8.8 m² / g would result in an overly porous coating structure with insufficient mechanical strength, making it prone to collapse and deformation during hot pressing and cell assembly, which is detrimental to maintaining a stable pore structure and compression resilience. In some typical embodiments, the specific surface area of ​​the first polymer is 8.8 m² / g. 2 / g~20.4m 2 / g.

[0032] Under the premise that the average particle size of the first polymer is maintained at 10μm~30μm, the smaller the particle size of the primary particles forming the first polymer, the richer the micropore and mesopore structure formed by particle accumulation, and the larger the overall specific surface area of ​​the material. Conversely, the larger the particle size of the primary particles forming the first polymer, the smaller the particle accumulation porosity and the lower the proportion of internal pores, and the smaller the specific surface area of ​​the material. Therefore, the specific surface area of ​​the first polymer can be made to 8m² by controlling the particle size of the primary particles. 2 / g~25m 2 / g.

[0033] In some optional embodiments, the elastic modulus of the first polymer can be 9 MPa to 20 MPa, such as 9 MPa, 10 MPa, 12 MPa, 15 MPa, 18 MPa, or 20 MPa, or other values ​​within the range of 9 MPa to 20 MPa. If the elastic modulus of the first polymer is less than 9 MPa, it is not conducive to providing sufficient structural support for the coating, the coating is too soft overall, and it is prone to excessive compression deformation during hot pressing and cell assembly, leading to pore collapse and ion channel blockage. At the same time, the compression resilience is poor, making it difficult to maintain dimensional stability during long-term cycling. If the elastic modulus of the first polymer is greater than 20 MPa, it is not conducive to the interfacial compatibility between the coating and the base film and electrode sheet. Overly hard particles will reduce the overall toughness of the coating, making it prone to stress concentration, coating cracking or peeling from the base film. At the same time, the interfacial adhesion deteriorates, which is not conducive to improving bonding reliability and cell safety and stability. In some more typical embodiments, the elastic modulus of the first polymer is 9.8 MPa to 18.9 MPa.

[0034] In some alternative embodiments, the first polymer is polymerized from monomer A, which, by way of example but not limitation, may include at least one selected from vinylidene fluoride, methyl methacrylate, ethyl methacrylate, methacrylonitrile, butyl methacrylate, styrene, acrylonitrile, methacrylonitrile, and 2-ethylhexyl methacrylate. By way of example, monomer A may include 42 to 58 parts of methyl methacrylate, 22 to 40 parts of butyl methacrylate, and 18 to 20 parts of styrene.

[0035] For example, the synthesis of the first polymer can be described as follows: spray drying and granulation of an emulsion containing primary particles polymerized from monomer A. The solid content of the emulsion can be 18wt%~25wt% (e.g., 18wt%, 19wt%, 20wt%, 21wt%, 22wt%, 23wt%, 24wt%, or 25wt%), the inlet air temperature for spray drying and granulation can be 153℃~157℃ (e.g., 153℃, 154℃, 155℃, 156℃, or 157℃), the feed rate can be 4.0kg / h~5.0kg / h (e.g., 4.0kg / h, 4.2kg / h, 4.5kg / h, 4.8kg / h, or 5.0kg / h), and the outlet air temperature can be 64℃. The spray drying temperature can be ℃~66℃ (e.g., 64℃, 64.5℃, 65℃, 65.5℃, or 66℃, etc.), the atomization speed can be 19000rpm~23000rpm (e.g., 19000rpm, 20500rpm, 21000rpm, 21500rpm, 22000rpm, 22500rpm, or 23000rpm, etc.), and the drying air velocity during the spray drying process can be 1.5m / s~2.1m / s (e.g., 1.5m / s, 1.6m / s, 1.7m / s, 1.8m / s, 1.9m / s, 2m / s, or 2.1m / s, etc.). By adopting the above method, it can be ensured that the primary particles are loosely agglomerated without excessive adhesion and that the pores do not collapse, ultimately obtaining secondary particles (first polymer) with multiple pores formed by the agglomeration of primary particles.

[0036] The solid content of the emulsion and the spray drying conditions mentioned above affect the agglomeration of secondary particles, which in turn affects the specific surface area and average particle size of the primary polymer. If the solid content is below 18 wt%, the particle concentration in the emulsion system will be low, making it difficult for primary particles to agglomerate effectively during spray drying. The secondary particles will have poor formability, an overly loose structure, a large specific surface area, and insufficient mechanical strength, making them prone to breakage in subsequent processing. If the solid content is above 25 wt%, the emulsion viscosity will be too high, resulting in uneven atomization and excessive adhesion and fusion of primary particles. The resulting secondary particles will have a dense structure, collapsed pores, and a low specific surface area, which is not conducive to the formation of a porous support structure. If the feed rate is too high, the droplet solid content will be high, the agglomerate particle size will be large, the structure will be dense, and the specific surface area will be reduced. If the feed rate is too low, the droplet solid content will be low, the agglomerate particle size will be small, the pores will be well-developed, and the specific surface area will be increased. If the atomization speed is less than 19,000 rpm, it will lead to liquid... Poor atomization, excessively large particle size, and high degree of particle agglomeration result in secondary particles with an average particle size that is too large and insufficient internal porosity, leading to a low specific surface area. If the atomization speed exceeds 23,000 rpm, the droplets will be too fine, drying will be too fast, primary particles will not be able to fully loosen and agglomerate, secondary particles will not form completely, and a large amount of fine powder will be generated, with uneven particle size distribution. If the drying air velocity is less than 1.5 m / s, the hot air circulation in the tower will be insufficient, moisture will evaporate slowly, particles will easily stick together and clump, secondary particle density will increase, and porosity and specific surface area will decrease. If the drying air velocity is greater than 2.1 m / s, the particle residence time in the tower will be too short, resulting in insufficient drying. At the same time, excessive airflow disturbance will easily cause the formed secondary particles to break, resulting in uneven particle size and poor structural stability.

[0037] In some optional embodiments, the second polymer is in the form of primary particles, and the average particle size of the second polymer can be 0.4 μm to 1 μm, such as 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, or 1 μm, or other values ​​within the range of 0.4 μm to 1 μm. If the average particle size of the second polymer is less than 0.4 μm, it is easy to overfill and block the through pores inside the coating, significantly increasing the ion transport resistance and hindering the rapid migration of lithium ions; at the same time, fine particles have a large specific surface area and are prone to agglomeration in the slurry, resulting in localized thickening and uneven structure of the coating, which also increases the difficulty of liquid absorption and retention in the coating and reduces the electrolyte wetting efficiency. If the average particle size of the second polymer is greater than 1 μm, it is easy to make the overall coating thickness too high and the uniformity poor, resulting in a high coating compression ratio and insufficient rebound after hot pressing, which is not conducive to maintaining a stable pore structure; it also reduces the tightness of the coating and the electrode sheet, affecting the stability of the cell interface and cycle performance. In some typical embodiments, the average particle size of the second polymer can be 0.46 μm to 0.93 μm.

[0038] In some optional embodiments, the average particle size variation coefficient of the second polymer is CV, where CV ≤ 5%, and can be 5%, 4%, 3%, 2%, or 1%, or other values ​​within the range of ≤ 5%. If the average particle size variation coefficient of the second polymer is greater than 5%, it is detrimental to the uniformity of the coating thickness and structure, easily leading to areas with excessively large or small particle sizes, resulting in problems such as local pore blockage and insufficient adhesion. Simultaneously, it can cause uneven stress distribution within the coating, making it prone to local over-compaction or under-compaction during hot pressing, resulting in poor compression ratio stability, disordered ion transport channel distribution, and ultimately affecting the overall performance consistency and cycle reliability of the battery cell. The average particle size variation coefficient of the second polymer can be calculated using the following formula: CV = (Standard deviation of second polymer particle size / Average particle size of second polymer) × 100%. In some typical embodiments, the average particle size variation coefficient CV of the second polymer is 4.6%~4.8%.

[0039] In some optional embodiments, the glass transition temperature of the second polymer is ≤80°C, such as 80°C, 70°C, 60°C, 50°C, 40°C, 30°C, 20°C, or 10°C, or other values ​​within the ≤80°C range. If the glass transition temperature of the second polymer is greater than 80°C, it is not conducive to achieving sufficient softening and flow at conventional hot pressing process temperatures, resulting in a significant decrease in the adhesion between the coating and the base film and electrode sheet, and insufficient interfacial adhesion. In some more typical embodiments, the glass transition temperature of the second polymer is 50.7°C to 75.1°C.

[0040] In some optional embodiments, the gelation rate of the second polymer can be 80% to 98%, such as 80%, 82%, 88%, 90%, 92%, 95%, or 98%, or other values ​​within the range of 80% to 98%. If the gelation rate of the second polymer is less than 80%, it is not conducive to ensuring the structural stability of the binder phase. Under long-term immersion in the electrolyte, it is prone to excessive swelling or even dissolution, leading to a decrease in coating adhesion strength, powdering and detachment, and an increase in the internal impedance of the battery cell, affecting cycle life. If the gelation rate of the second polymer is greater than 98%, it will result in excessive cross-linking of polymer particles, softening and poor wettability, making it difficult to fully melt and spread during hot pressing, reducing the adhesion strength with the base film and electrode, and causing insufficient coating toughness, poor compression deformation and resilience performance, which is not conducive to maintaining stable interfacial bonding and pore structure. In some more typical embodiments, the gelation rate of the second polymer is 90.0% to 96.4%.

[0041] In some alternative embodiments, the second polymer is polymerized from monomer B, which may, by way of example but not limitation, include at least one of methyl methacrylate, ethyl methacrylate, methacrylonitrile, butyl methacrylate, styrene, acrylonitrile, methacrylonitrile, and 2-ethylhexyl methacrylate.

[0042] For example, monomer B may include 40 parts ethyl methacrylate, 30 to 45 parts acrylonitrile, and 15 to 30 parts 2-ethylhexyl methacrylate. By varying the monomer formulations and polymerization temperatures, second polymers with different glass transition temperatures can be obtained.

[0043] For example, during the synthesis of the second polymer, a crosslinking agent comprising 0.45% to 1.1% of the total mass of monomer B is added. The crosslinking agent may, by example but not exclusively, include at least one of ethylene glycol dimethacrylate (EGDMA), polyethylene glycol dimethacrylate (PEGDMA), trimethylolpropane trimethacrylate (TMPTMA), trimethylolpropane triacrylate (TMPTA), allyl methacrylate (AMA), and divinylbenzene (DVB). The addition of the aforementioned crosslinking agent can affect the crosslinking density, gel ratio, glass transition temperature, and mechanical properties of the second polymer, thereby controlling its dry and wet pressure bonding strength with the electrode, electrolyte wettability, and structural stability. If the amount of crosslinking agent added is too small, it is not conducive to the formation of a stable three-dimensional crosslinked network, and the gel rate of the second polymer is difficult to reach more than 80%. Under long-term immersion in electrolyte, it is prone to swelling and dissolution, resulting in the attenuation of coating adhesion strength and failure to guarantee long-term adhesion performance with the electrode. If the amount of crosslinking agent added is too large, it will lead to excessive crosslinking of the second polymer, raising the glass transition temperature to above 80°C, increasing the rigidity of the polymer and decreasing its toughness. It is difficult to fully melt and spread during hot pressing, reducing the interfacial adhesion with the electrode and base film, and decreasing the dry and wet pressing adhesion strength. This is not conducive to maintaining a stable pore structure and cell assembly compatibility.

[0044] For example, the polymerization temperature of the second polymer can be 73°C to 85°C. During the synthesis of the second polymer, the stirring speed can be 280 rpm to 420 rpm.

[0045] In some alternative embodiments, the coating also contains additives, the mass percentage of which may be 2% to 8%, such as 2%, 3%, 4%, 5%, 6%, 7%, or 8%, or other values ​​within the range of 2% to 8%, such as 2% to 7%. The additives may, by way of example but not by way of limitation, include at least one of styrene-butadiene rubber, polyacrylate, polyacrylamide, polyacrylonitrile, and epoxy resin.

[0046] In some alternative embodiments, the areal density of the coating in the coated diaphragm is 0.4 g / m³.2 ~1.2g / m 2 For example, 0.4g / m 2 0.6g / m 2 0.8g / m 2 1g / m 2 Or 1.2g / m 2 etc., can also be 0.4g / m 2 ~1.2g / m 2 Other values ​​within the range. In some typical embodiments, the areal density of the coating is 0.42 g / m³. 2 ~1.12g / m 2 .

[0047] In some optional embodiments, the initial thickness of the coating in the coated diaphragm can be 11 μm to 30 μm, such as 11 μm, 15 μm, 20 μm, 25 μm, or 30 μm, or other values ​​within the range of 11 μm to 30 μm. In some more typical embodiments, the initial thickness of the coating is 11.9 μm to 25.9 μm.

[0048] In some optional embodiments, the compression ratio of the coated diaphragm under hot pressing at 1 MPa, 85°C, and 1 hour is X1, where 20% ≤ X1 ≤ 55%. X1 can be 20%, 25%, 30%, 35%, 40%, 45%, 50%, or 55%, or other values ​​within the range of 20% to 55%. In some more typical embodiments, X1 is 27% to 50%.

[0049] In some optional embodiments, the compression ratio of the coated diaphragm under hot pressing at 2 MPa, 85°C, and 1 hour is X2, where 40% ≤ X2 ≤ 70%. For example, X2 can be 40%, 50%, 60%, or 70%, or other values ​​within the range of 40% to 70%. In some more typical embodiments, X2 is 42% to 64%.

[0050] In some preferred embodiments, X2 < 2X1.

[0051] In some optional embodiments, the liquid retention rate (ER1) of the coated diaphragm after hot pressing at 1 MPa, 85°C, and 1 hour is 130% ≤ ER1 ≤ 270%, such as ER1 being 130%, 150%, 170%, 200%, 220%, 250%, or 270%, or other values ​​within the range of 130% to 270%. In some more typical embodiments, ER1 is 134% to 212%.

[0052] In some optional embodiments, the liquid retention rate (ER2) of the coated diaphragm after hot pressing at 2 MPa, 85°C, and 1 hour is 100% ≤ ER2 ≤ 160%, such as ER2 being 100%, 110%, 120%, 130%, 140%, 150%, or 160%, or other values ​​within the range of 100% to 160%. In some more typical embodiments, ER2 is 104% to 158%.

[0053] In some optional embodiments, the dry-press adhesion force between the coated diaphragm and the electrode sheet under hot pressing at 1 MPa, 85°C, and 85 s is F1, where 2 N / m ≤ F1 ≤ 15 N / m. F1 can be 2 N / m, 5 N / m, 8 N / m, 10 N / m, 12 N / m, or 15 N / m, or other values ​​within the range of 2 N / m to 15 N / m. In some more typical embodiments, F1 is 3.4 N / m to 12.9 N / m.

[0054] In some optional embodiments, the dry-press adhesion force between the coated diaphragm and the electrode sheet under hot pressing at 2 MPa, 85°C, and 85 s is F2, where 2.5 N / m ≤ F2 ≤ 20 N / m. F2 can be 2.5 N / m, 5 N / m, 10 N / m, 15 N / m, or 20 N / m, or other values ​​within the range of 2.5 N / m to 20 N / m. In some more typical embodiments, F2 is 4.1 N / m to 18.6 N / m.

[0055] In some preferred embodiments, F2 > F1.

[0056] In some optional embodiments, the wet pressure adhesion force between the coated diaphragm and the electrode sheet under 1 MPa conditions is F3, where 4 N / m ≤ F3 ≤ 26 N / m. In some more typical embodiments, F3 is 4.5 N / m to 25.1 N / m.

[0057] In some optional embodiments, the wet pressure adhesion force between the coated diaphragm and the electrode sheet under 2 MPa conditions is F4, where 5 N / m ≤ F4 ≤ 38 N / m. In some more typical embodiments, F4 is 5.8 N / m to 36.5 N / m.

[0058] Accordingly, the present invention also provides a method for preparing the above-mentioned coated diaphragm, comprising the following steps: coating a slurry containing at least a first polymer and a second polymer onto at least one side surface of a base membrane, and drying.

[0059] In some alternative implementations, the coating is applied in a discontinuous dotted pattern.

[0060] In addition, the present invention also provides a battery cell comprising the above-described coated separator.

[0061] In some alternative embodiments, the aforementioned battery cell is a square wound battery cell (e.g., Figure 3 ).

[0062] By using the coated separator provided by this invention, the safety performance and service life of the battery cell can be significantly improved compared with the prior art. For example, the battery cell qualification rate can be increased by 3% (e.g., increased to no less than 95%, such as 95.4%~97.5%), the proportion of lithium plating area at corners can be reduced to ≤3.1% (e.g., reduced to 0%~3.1%), the interface impedance can be reduced by 30%-50%, the battery cell cycle life can be extended by 50%-80%, and the capacity retention rate of the battery cell after 500 cycles can be increased to no less than 95%, such as 95.0%~98.9%.

[0063] Furthermore, the present invention also provides a battery comprising the aforementioned battery cell. This battery may also have superior safety and performance characteristics.

[0064] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0065] Example 1 This embodiment provides a coated diaphragm, the preparation of which includes: dispersing 80% of a first polymer, 15% of a second polymer, and 5% of an additive (polyacrylate) in deionized water by weight percentage to prepare a slurry with a solid content of 8 wt%. A discontinuous dot-matrix coating is then applied to one side of a wet-process biaxially oriented polypropylene base film with a thickness of 9 μm using a gravure coating method. After drying at 60°C, a coating surface density of 0.8 g / m² is obtained. 2 The coated diaphragm.

[0066] The synthesis method of the first polymer is as follows: 350 parts of deionized water are added to a reactor, along with 1.0 part of sodium dodecyl sulfate and 0.2 parts of sodium bicarbonate, and stirred until homogeneous. Then, 100 parts of a monomer mixture A, consisting of 50 parts of methyl methacrylate, 30 parts of butyl methacrylate, and 20 parts of styrene, are added. Stirring is started and the speed is controlled at 300 rpm. After heating to 80°C, 0.3 parts of ammonium persulfate initiator are added. The monomer addition is completed within 2 hours using a semi-continuous dripping method. Polymerization is maintained at this temperature for 6 hours, followed by ripening at 85°C for 1 hour, yielding a primary granular emulsion with a solid content of 22.5 wt% and an average primary particle size of 180 nm. The above primary granular emulsion is then spray-dried and granulated using the following process parameters: inlet air temperature of 155°C, feed rate of 4.5 kg / h, outlet air temperature of 65°C, atomization speed of 21000 rpm, and a drying air velocity controlled at 1.8 m / s during spray drying to obtain the first polymer.

[0067] The synthesis method of the second polymer is as follows: Take 300 parts of deionized water, add 1.5 parts of sodium dodecylbenzenesulfonate, 100 parts of monomer B mixture consisting of 40 parts of ethyl methacrylate, 30 parts of acrylonitrile, and 30 parts of 2-ethylhexyl methacrylate, control the stirring speed at 350 rpm, heat to 80℃, add 0.25 parts of ammonium persulfate and 0.8 parts of crosslinking agent (polyethylene glycol dimethacrylate), keep at the temperature for polymerization for 6 hours, and then mature for 1 hour to obtain the second polymer emulsion.

[0068] Example 2 The difference between this embodiment and Embodiment 1 is that: in the synthesis of the first polymer, the solid content of the primary particulate emulsion is 18.5 wt%; the feed rate is 4.1 kg / h; and the atomization speed in the spray drying granulation is 22,500 rpm and the drying wind speed is 2.0 m / s.

[0069] Example 3 The difference between this embodiment and Embodiment 1 is that: in the synthesis of the first polymer, the solid content of the primary particulate emulsion is 25wt%; the feed rate is 4.9kg / h; and the atomization speed in the spray drying granulation is 19500rpm and the drying wind speed is 1.6m / s.

[0070] Example 4 The difference between this embodiment and Embodiment 1 is that: in the synthesis of the first polymer, the solid content of the primary particulate emulsion is 21wt%; the feed rate is 4.0kg / h; and the atomization speed in the spray drying granulation is 23000rpm and the drying wind speed is 2.1m / s.

[0071] Example 5 The difference between this embodiment and Embodiment 1 is that: in the synthesis of the first polymer, the solid content of the primary particulate emulsion is 24wt%; the feed rate is 5.0kg / h; and the atomization speed in the spray drying granulation is 19000rpm and the drying wind speed is 1.5m / s.

[0072] Example 6 The difference between this embodiment and Example 1 is that in the synthesis of the first polymer, there are 42 parts of methyl methacrylate, 40 parts of butyl methacrylate, and 18 parts of styrene.

[0073] Example 7 The difference between this embodiment and Embodiment 1 is that: in the synthesis of the first polymer, there are 58 parts of methyl methacrylate, 22 parts of butyl methacrylate, and 20 parts of styrene.

[0074] Example 8 The difference between this embodiment and Example 1 is that the stirring speed was adjusted to 420 rpm during the synthesis of the second polymer, and the amount of crosslinking agent (polyethylene glycol dimethacrylate) was adjusted to 1.1 parts.

[0075] Example 9 The difference between this embodiment and Embodiment 1 is that the stirring speed is adjusted to 280 rpm during the synthesis of the second polymer, and the amount of crosslinking agent (polyethylene glycol dimethacrylate) is adjusted to 0.5 parts.

[0076] Example 10 The difference between this embodiment and Example 1 is that in the synthesis of the second polymer, 40 parts of ethyl methacrylate, 45 parts of acrylonitrile, and 15 parts of 2-ethylhexyl methacrylate are used.

[0077] Example 11 The difference between this embodiment and Embodiment 1 is that in the synthesis of the second polymer, the crosslinking agent polyethylene glycol dimethacrylate is reduced from 0.8 parts to 0.45 parts.

[0078] Example 12 The difference between this embodiment and Embodiment 1 is that the areal density of the coated diaphragm is 0.42 g / m³. 2 .

[0079] Example 13 The difference between this embodiment and Embodiment 1 is that the areal density of the coated diaphragm is 1.12 g / m³. 2 .

[0080] Example 14 The difference between this embodiment and Embodiment 1 is that, by mass percentage, the coating contains 88% of the first polymer, 10% of the second polymer, and 2% of the additive (polyacrylate).

[0081] Example 15 The difference between this embodiment and Embodiment 1 is that, by mass percentage, the coating contains 68% of the first polymer, 25% of the second polymer, and 7% of the additive (polyacrylate).

[0082] Comparative Example 1 The difference between this comparative example and Example 1 is that the coating does not contain the second polymer, and the coating consists of 95 wt% of the first polymer and 5 wt% of polyacrylate additives.

[0083] Comparative Example 2 The difference between this comparative example and Example 1 is that the coating does not contain the first polymer, and the coating consists of 95 wt% of the second polymer and 5 wt% of polyacrylate additives.

[0084] Comparative Examples 3 to 8 The difference between Comparative Examples 3 to 8 and Example 1 is that the first polymer and the second polymer used in each comparative example are different from those in Example 1, as shown in Table 1.

[0085] Experimental Example 1 The characteristics of each polymer in Examples 1-15 and Comparative Examples 1-8 were compared, and the results are shown in Table 1. The testing methods for each characteristic are as follows: (1) Test of average particle size of polymer: The average particle size of the first polymer (denoted as D1) and the second polymer (denoted as D2) were tested using a laser particle size analyzer (Malvin 3000); the test parameters were: refractive index 1.52, absorptivity 0.1, and occlusion 8%~16%.

[0086] The average particle size of the first polymer particles was measured by scanning electron microscopy (SEM) to obtain the average particle size (denoted as d1).

[0087] (2) Test of the specific surface area (denoted as S) of the first polymer: The low-temperature nitrogen adsorption-desorption method was used, and the test was performed in accordance with GB / T 19587-2004. The first polymer sample was first pretreated by vacuum drying at 105±2℃ for 2h, weighed and loaded into the adsorption instrument. High-purity nitrogen was introduced at -196℃ to complete the adsorption-desorption. The specific surface area was calculated using the BET model. The test results were taken as the average of 3 parallel experiments, with a deviation ≤2%.

[0088] (3) Test of the first polymer elastic modulus (denoted as E): The first polymer elastic modulus was tested using a universal testing machine according to the standard GB / T 1040.1-2018. The sample was compressed into a standard specimen and subjected to compression or tension tests at a constant rate at room temperature. The stress-strain curve was recorded, and the elastic modulus was calculated by taking the slope of the initial linear segment of the curve. The result was the average of three parallel tests.

[0089] (4) The average particle size variation coefficient of the second polymer is CV: The particle size distribution of the second polymer was tested using a laser particle size analyzer, and the standard deviation of particle size and the volume average particle size D were obtained. 50 The coefficient of variation is calculated using the formula CV = (standard deviation of particle size / average particle size) × 100%.

[0090] (5) Test of the glass transition temperature (Tg) of the second polymer: Differential scanning calorimetry (DSC) was used for the test, in accordance with GB / T 19466 standard. Under nitrogen atmosphere, the temperature was scanned at a heating rate of 10℃ / min, and the inflection point temperature of the second heating curve was taken as the glass transition temperature.

[0091] (6) Second polymer gel rate test: The second polymer emulsion is made into a uniform film and dried to constant weight, recorded as m1; the film is fully soaked in tetrahydrofuran, stored at room temperature for 72h, taken out and cleaned with alcohol, and dried again to constant weight, recorded as m2; gel rate = m2 / m1×100%.

[0092] Table 1 Polymer Characteristics

[0093] Experimental Example 2 The coated membranes of Examples 1-15 and Comparative Examples 1-9 were subjected to the following performance tests, and the test methods are as follows: (1) Coating surface density: Using a sample cutter, cut the uncoated base film and the corresponding coated separator into identical regular areas (0.01m²). 2 Three samples were cut in parallel for each group. The samples were placed in a constant temperature drying oven and dried to constant weight. The mass of the base film sample and the mass of the coated diaphragm sample after drying were weighed on a precision analytical balance. The density of the coating was calculated by subtracting the mass of the base film from the mass of the coated diaphragm per unit area. The arithmetic mean of the three parallel samples was taken as the final test result.

[0094] (2) Coating thickness H1 test before hot pressing: The thickness of the base film and the total thickness of the coated diaphragm were tested using a Mitutoyo VL-50 thickness gauge. The coating thickness was obtained by subtracting the base film thickness from the total thickness of the coated diaphragm. Ten different test points were selected during the test, and the average value was taken as the final result.

[0095] (3) Dry pressing adhesion test: The coated diaphragm and electrode sheet are hot-pressed together under the temperature and pressure conditions shown in Table 2 and Table 3. The tensile tester is used to stretch the electrode sheet in a 180° peeling manner, and the stable peeling force is recorded. The peeling strength per unit width is calculated as the dry pressing adhesion force.

[0096] (4) Test of coating thickness H2 or H3 after hot pressing: Using a Mitutoyo VL-50 thickness gauge, the total thickness of the coated diaphragm and the thickness of the base film after hot pressing under the conditions in Table 2 and Table 3 are tested respectively. The coating thickness H2 or H3 after hot pressing is obtained by subtracting the base film thickness from the total thickness of the coated diaphragm after hot pressing. Ten different test points are selected during the test, and the average value is taken as the final result.

[0097] (5) Compression ratio test: Compression ratio = (thickness of the diaphragm before hot pressing H1 - thickness of the diaphragm after hot pressing H2 or H3) / thickness of the diaphragm before hot pressing H1 × 100%. The coating compression ratios X1 and X2 are calculated under different hot pressing conditions according to the hot pressing conditions in Table 2 and Table 3.

[0098] (6) Wet pressure adhesion test: First, the coated separator, positive electrode and negative electrode are cut into samples of fixed specifications. The cut positive electrode, separator and negative electrode are stacked and assembled into a single-layer stacked cell. The cell is pre-pressed at 65℃, 1MPa and 15s. After being packaged with aluminum-plastic film and injected with electrolyte, it is formed at 85℃ under the wet pressure test pressure in Table 2 and Table 3, and then aged at 45℃. The cell is then discharged to 3V and disassembled and sampled in a drying room. The 180° peel test of the separator and electrode composite sample is performed using a universal testing machine. The peel strength obtained is the wet pressure adhesion.

[0099] (7) Diaphragm liquid retention rate test: Cut the diaphragm to the specified size, and use a laboratory hot press at 1MPa and 85℃ for 1h, weigh the dry weight and record it as m0; immerse the diaphragm completely in the electrolyte and let it stand at 25℃ for 2h to allow it to fully absorb the liquid; remove the diaphragm, quickly wipe off the free electrolyte on the surface with lint-free paper, weigh the wet weight and record it as m1; calculate the liquid retention rate according to the following formula: Liquid retention rate ER1=(m1-m0) / m0×100%. Similarly, obtain the liquid retention rate ER2 corresponding to 2MPa and 85℃ hot pressing for 1h.

[0100] The results are shown in Tables 2 and 3.

[0101] Table 2 Test Results

[0102] Table 3 Test Results

[0103] Experimental Example 3 The above Examples 1-15 and Comparative Examples 1-9 were wound into battery cells as follows: The coated separator, silicon-carbon negative electrode sheet, and ternary positive electrode sheet were neatly stacked in the order of positive electrode-separator-negative electrode, with a winding layer count controlled at 30 layers. During the winding process, the C-corner winding curvature was ensured to be uniform, with no slippage or wrinkles between layers. After the bare core was formed, a pre-pressing treatment was performed at a pressure of 1 MPa, a temperature of 65°C, and a pre-pressing time of 15 seconds to expel air between the bare core layers and initially fix the relative positions of the electrode sheet and the separator. The hot-pressed bare core was placed into a soft-pack aluminum-plastic film shell with a punched-in groove and a reserved air bag area. Electrolyte was injected using a vacuum injection method, with the injection volume controlled to be 1.2 times the pore volume of the bare core. After injection, the sides and top were initially sealed. A dedicated air bag cavity was retained during sealing to accommodate gas generated in subsequent processes. The battery cell was then placed at a temperature of 45°C and a relative humidity ≤10%. The cells were placed in a dry environment for 24 hours to allow the electrolyte to fully wet the silicon-carbon anode, cathode, and coated membrane pores. After initial settling, the cells were placed in a constant temperature and pressure environment of 85°C and 1MPa, and constant current and constant pressure formation was performed using a small current of 0.1C. The formation cutoff voltage was 4.2V±0.01V, and the formation was terminated when the charging current dropped to 0.01C. The gases generated during the formation process were collected in the pre-reserved gas bags in the aluminum-plastic film. After formation, the cells were placed in a constant temperature aging chamber at 45°C for 72 hours. After aging, the gas bag area was vacuum-evacuated, excess gas bags were cut off, and secondary sealing was performed. After natural cooling to room temperature, cells with poor appearance and electrical properties were sorted and rejected, and finally, the soft-pack square wound cells to be tested were obtained.

[0104] The performance of the battery cells was tested using the following methods, and the results are shown in Table 4.

[0105] (1) Cell thickness pass rate: After formation and aging, the square wound cells are placed in a constant temperature environment and allowed to stand until the temperature is uniform. High-precision thickness testing is performed at multiple preset locations on the cells, and the actual thickness of each cell is recorded. The cell thickness tolerance range set by the process is used as the judgment standard. The actual thickness falling within the tolerance range is judged as qualified, and the thickness exceeding the tolerance range is judged as unqualified. Cell thickness pass rate = number of qualified cells / total number of tested cells × 100%.

[0106] (2) Percentage of lithium plating area at cell corner: After cycling, the cell is disassembled in a dry room and the separator and electrode are separated. The electrode in the C corner area of ​​the square cell is selected and photographed using a super depth-of-field microscope. The total area of ​​the C corner area and the area of ​​the lithium plating area are calculated by image analysis software. Percentage of lithium plating area at cell corner = area of ​​lithium plating area in C corner / total area of ​​C corner area × 100%.

[0107] (3) Capacity retention rate of the cell after 500 cycles: The cell under test was subjected to a standard charge-discharge cycle test at a normal temperature of 25℃±2℃: it was charged at a constant current and constant voltage of 0.5C to the cutoff voltage, and then discharged at a constant current of 0.5C to the discharge cutoff voltage after resting. The charge-discharge cycle was completed sequentially. The discharge capacity of the first cycle was recorded as the initial capacity. The cycle was continued until 500 cycles, and the discharge capacity of the 500th cycle was recorded. Capacity retention rate = discharge capacity of the 500th cycle / initial capacity × 100%.

[0108] Table 4 Test Results

[0109] As can be seen from Tables 2 to 4 above, the coated separator provided in the embodiments of the present invention can effectively improve the safety performance and service life of the battery cell.

[0110] In summary, the coated separator provided by this invention can improve the adhesion, liquid retention rate, and stress buffering capacity of the separator in the C-corner region of a square wound battery cell, thereby improving the battery cell production qualification rate, reducing the risk of lithium plating, and extending the battery cell cycle life.

[0111] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A coated diaphragm with high liquid storage and high adhesion performance, characterized in that, The high liquid storage and high adhesion performance coated diaphragm includes a base membrane and a coating disposed on at least one surface of the base membrane; The coating contains a first polymer and a second polymer; The first polymer consists of secondary particles formed by primary particle agglomeration, with an average particle size of 10 μm to 30 μm and a specific surface area of ​​8 m². 2 / g~25m 2 / g, with an elastic modulus of 9MPa~20MPa; The average particle size of the second polymer is 0.4 μm to 1 μm, and the glass transition temperature of the second polymer is ≤80℃.

2. The high liquid storage and high adhesion performance coated diaphragm according to claim 1, characterized in that, The average particle size of the primary particles in the first polymer is 100 nm to 800 nm; And / or, the first polymer is polymerized from monomer A, which includes at least one of vinylidene fluoride, methyl methacrylate, ethyl methacrylate, methacrylonitrile, butyl methacrylate, styrene, acrylonitrile, methacrylonitrile, and 2-ethylhexyl methacrylate.

3. The coated diaphragm according to claim 1, characterized in that, The average particle size variation coefficient of the second polymer is CV, and CV ≤ 5%; And / or, the gelation rate of the second polymer is 80%~98%.

4. The high liquid storage and high adhesion performance coated diaphragm according to claim 1, characterized in that, The second polymer is polymerized from monomer B, which includes at least one of methyl methacrylate, ethyl methacrylate, methacrylonitrile, butyl methacrylate, styrene, acrylonitrile, methacrylonitrile, and 2-ethylhexyl methacrylate.

5. The high liquid storage and high adhesion performance coated diaphragm according to claim 1, characterized in that, The coating comprises, by weight percentage, 68% to 88% of a first polymer and 10% to 25% of a second polymer.

6. The high liquid storage and high adhesion performance coated diaphragm according to claim 1, characterized in that, The coating also contains additives, which are present in the coating at a mass percentage of 2% to 8%, and / or the additives include at least one of styrene-butadiene rubber, polyacrylate, polyacrylamide, polyacrylonitrile, and epoxy resin.

7. The high liquid storage and high adhesion coated diaphragm according to claim 1, characterized in that, The high liquid storage and high adhesion coated diaphragm also has at least one of the following characteristics: Feature 1: The areal density of the coating is 0.4 g / m³. 2 ~1.2g / m 2 ; Feature 2: The high liquid storage and high adhesion performance coated diaphragm has a compression ratio of X1 under hot pressing at 1 MPa, 85℃, and 1 hour, where 20% ≤ X1 ≤ 55%. Feature 3: The high liquid storage and high adhesion performance coated diaphragm has a compression ratio of X2 under hot pressing at 2MPa, 85℃ and 1h, where 40%≤X2≤70%. Feature 4: The liquid retention rate of the high liquid storage and high adhesion coated diaphragm after hot pressing at 1MPa, 85℃ and 1h is ER1, 130%≤ER1≤270%; Feature 5: The liquid retention rate of the high liquid storage and high adhesion performance coated diaphragm after hot pressing at 2MPa, 85℃ and 1h is ER2, 100%≤ER2≤160%; Feature 6: The dry pressure adhesion force between the high liquid storage and high adhesion performance coated diaphragm and the electrode sheet under hot pressing at 1MPa, 85℃ and 85s is F1, 2N / m ≤F1≤15N / m; Feature 7: The dry pressing adhesion force between the high liquid storage and high adhesion performance coated diaphragm and the electrode sheet under hot pressing at 2MPa, 85℃ and 85s is F2, 2.5N / m ≤F2≤20N / m; Feature 8: The high liquid storage and high adhesion performance coated diaphragm has a wet pressure adhesion force of F3 to the electrode sheet under 1MPa conditions, 4N / m≤F3≤26N / m; Feature 9: The high liquid storage and high adhesion performance coated diaphragm has a wet pressure adhesion force of F4 to the electrode sheet under 2MPa conditions, 5N / m≤F4≤38N / m.

8. The high liquid storage and high adhesion coated diaphragm according to claim 7, characterized in that, X2 < 2X1; And / or, F2 > F1.

9. A method for preparing a coated diaphragm with high liquid storage and high adhesion performance as described in any one of claims 1 to 8, characterized in that, The process includes the following steps: coating a slurry containing at least a first polymer and a second polymer onto at least one side of the base film and drying it.

10. A battery, characterized in that, Including the high liquid storage and high adhesion performance coated diaphragm as described in claim 9.

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