Coating layer composition for use in separator, composite separator, battery cell, battery, and power consumption device

Abstract

The present application provides a coating layer composition for use in a separator, a composite separator, a battery cell, a battery, and a power consumption device. The coating layer composition for the separator includes porous phenolic resin microspheres and a binder, with the weight ratio of the binder to the porous phenolic resin microspheres being 1:1 to 1:20. The coating layer composition can be used to form a coating layer on the surface of a base film to obtain a composite separator, effectively reducing the thermal shrinkage of the base film and improving the safety of the battery cell. Furthermore, the composite separator has good ionic conductivity without significantly affecting the breathability of the base film, and the battery cell has good safety and high capacity retention.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to a Chinese patent application, filed on May 29, 2023, with application number 202310610594.7, entitled "Coating layer composition for separator, composite separator, battery cell, battery and power consumption device," the entire contents of which are incorporated herein by reference.

[0002] The present application relates to the field of lithium batteries, and more particularly to coating layer compositions used in separators, composite separators, battery cells, batteries, and power-consuming devices. [Background technology]

[0003] The battery cells have advantages such as reliable operation performance, no pollution, no memory effect, etc., and are therefore widely used. For example, as environmental protection issues become more and more important, new energy vehicles become more and more popular, and the demand for power battery cells is explosively increasing.

[0004] As the range of battery applications continues to expand, the requirements for battery safety are also becoming higher and higher. However, the separator in the battery cell has poor heat resistance, which leads to a decrease in safety, so the heat resistance of the separator needs to be improved. Summary of the Invention

[0005] The present application provides a coating layer composition for use in a separator that can improve the heat resistance of the separator, a composite separator, a battery cell, a battery, and a power consuming device.

[0006] According to a first aspect, the present application provides a coating layer composition for use in a separator, comprising porous phenolic resin microspheres and a binder, wherein the mass ratio of the binder to the porous phenolic resin microspheres is 1:1 to 1:20.

[0007] According to the present application, the coating layer composition can be used to form a coating layer on the surface of a base film to obtain a composite separator. The coating layer, which is primarily composed of porous phenolic resin microspheres as a skeleton, has good heat resistance and can effectively reduce the thermal shrinkage of the base film, preventing short circuits caused by contact between the positive and negative electrodes due to separator shrinkage under high temperature conditions in batteries, thereby improving the safety of the battery cell. Furthermore, the special porous structure does not significantly affect the breathability of the base film compared to conventional coating layers, and the resulting composite separator has good ionic conductivity, resulting in battery cells with good safety and high capacity retention.

[0008] In some embodiments, the binder includes at least one of polyacrylic acid, polyacrylic ester, polyvinylidene fluoride, styrene-butadiene rubber, and sodium carboxymethyl cellulose, which can stably bind the porous phenolic resin microspheres to the surface of the base film, improving the stability of the composite separator and further improving its heat resistance.

[0009] In some embodiments, the porous phenolic resin microspheres satisfy at least one of the following conditions: 1) The Dv50 particle size of the porous phenolic resin microspheres is 0.1 μm to 5 μm. 2) The average pore size of the porous phenolic resin microspheres is 10 nm to 50 nm. 3) The specific surface area of ​​the porous phenolic resin microspheres is 15 m 2 / g~280m 2 4) The total pore volume of the porous phenolic resin microspheres is 0.700 cm 3 / g~1.680cm 3 The composite separator thus obtained has better heat resistance or breathability, which is advantageous in improving the safety and capacity retention rate of a battery cell using the composite separator.

[0010] In some embodiments, the porous phenolic resin microspheres satisfy at least one of the following conditions: 1) The Dv50 particle size of the porous phenolic resin microspheres is 0.12 μm to 2 μm. 2) The average pore size of the porous phenolic resin microspheres is 15 nm to 40 nm. 3) The specific surface area of ​​the porous phenolic resin microspheres is 60 m 2 / g~265m 2 4) The total pore volume of the porous phenolic resin microspheres is 0.910 cm 3 / g~1.560cm 3 The composite separator thus obtained has better heat resistance or breathability, which is advantageous in improving the safety and capacity retention rate of a battery cell using the composite separator.

[0011] In some embodiments, the porous phenolic resin microspheres are obtained by reacting a phenolic compound with an aldehyde compound in a solvent in the presence of a catalytic amount of a phenol polycondensation catalyst and a pore-forming amount of a pore-forming agent. Different types of porous phenolic resin microspheres can be obtained by selecting different phenolic compounds and aldehyde compounds, and different particle sizes, pore sizes, specific surface areas, or total pore volumes can be obtained by controlling the reaction conditions. This allows for a high degree of design flexibility, allowing for the preparation of suitable porous phenolic resin microspheres according to actual needs.

[0012] In some embodiments, the molar ratio of the phenolic hydroxyl groups in the phenol compound to the aldehyde groups in the aldehyde compound is 1:1.1 to 1:1.6, which is advantageous in obtaining porous phenolic resin microspheres with good dispersity and stable properties, and ensures more stable performance of the coating layer formed from the coating layer composition.

[0013] In some embodiments, the phenolic compound includes at least one of phenol, hydroquinone, resorcinol, catechol, cresol, and cardanol, the aldehyde compound includes formaldehyde and / or paraformaldehyde, the phenol polycondensation catalyst is an alkaline substance including at least one of sodium hydroxide, aqueous ammonia, triethylamine, barium hydroxide, and aniline, and the pore-forming agent includes at least one of toluene, ethylene glycol, diethyl phthalate, octyl phthalate, and octadecanol. The raw materials for producing porous phenolic microspheres are inexpensive, readily available, and diverse, allowing selection according to actual needs and suitable for industrial production.

[0014] According to a second aspect, the present application provides a composite separator including a base film and a coating layer formed on at least one surface of the base film by the coating layer composition according to any one of the embodiments of the first aspect.

[0015] According to the present application, the composite separator includes a coating layer formed from the coating layer composition according to any of the embodiments of the first aspect, and therefore, as will be appreciated, the composite separator has the beneficial effects of the first aspect.

[0016] In some embodiments, the coating layer has an areal density of 0.1 g / m 2 ~5g / m 2 In this case, the composite separator has better heat resistance and breathability, which results in a battery cell with higher safety and capacity retention.

[0017] In some embodiments, the composite separator satisfies 1.25≦D / d≦62.5, where D is the Dv50 particle size of the porous phenolic microspheres and d is the average pore size of the base film, which not only ensures the heat resistance and breathability of the composite separator but also reduces the thickness of the coating layer, thereby improving the energy density of the battery cell.

[0018] In some embodiments, the composite separator satisfies 1.5≦D / d≦25. This not only ensures the heat resistance and breathability of the composite separator, but also allows the thickness of the coating layer to be further reduced, thereby further improving the energy density of the battery cell.

[0019] According to a third aspect, the present application provides a battery cell comprising the composite separator according to any embodiment of the second aspect.

[0020] According to the present application, the battery cell includes a composite separator according to any embodiment of the second aspect, and therefore, it will be understood that the battery cell has the beneficial effects of the second aspect.

[0021] According to a fourth aspect, the present application provides a battery comprising a battery cell according to any embodiment of the third aspect.

[0022] According to a fifth aspect, the present application provides a power consuming device comprising at least one of a battery cell according to any embodiment of the third aspect, or a battery according to any embodiment of the fourth aspect.

[0023] The present application provides a coating layer composition, which can be used to form a coating layer on the surface of a base film to obtain a composite separator. The composite separator has good heat resistance and breathability, thereby enabling the production of a battery cell with good safety and high capacity retention. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is an electron microscope image of the surface morphology of porous phenolic resin microspheres according to an embodiment of the present application. [Figure 2] 1 is an electron microscope image of a mechanical cross-sectional shape of a porous phenolic resin microsphere according to an embodiment of the present application. [Figure 3] 1 is a schematic diagram of a battery cell according to an embodiment of the present application; [Figure 4] FIG. 4 is an exploded view of the battery cell shown in FIG. 3 according to an embodiment of the present application. [Figure 5] 1 is a schematic diagram of a battery module according to an embodiment of the present application; [Figure 6] 1 is a schematic diagram of a battery according to an embodiment of the present application. [Figure 7] FIG. 7 is an exploded view of the battery shown in FIG. 6 according to an embodiment of the present application. [Figure 8] 1 is a schematic diagram of a power consuming device that uses a battery cell as a power source according to an embodiment of the present application. [Explanation of symbols]

[0025] 1 battery, 2 upper housing, 3 lower housing, 4 battery module, 5 battery cell, 51 housing, 52 electrode assembly, 53 top cover assembly. DETAILED DESCRIPTION OF THE INVENTION

[0026] Hereinafter, embodiments specifically disclosing the coating layer composition used in the separator, battery cell, battery, and power consumption device of the present application will be described in detail with reference to the accompanying drawings as appropriate. However, unnecessary details may be omitted. For example, detailed descriptions of well-known matters and redundant descriptions of structures that are actually the same may be omitted. This is to avoid unnecessarily lengthening the following description and to facilitate understanding by those skilled in the art. Note that the drawings and the following description are provided to enable those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0027] The "ranges" disclosed herein are defined in the form of lower and upper limits, and a given range is defined by selecting one lower limit and one upper limit, with the selected lower and upper limits defining the boundaries of the particular range. Such defined ranges may be inclusive or exclusive of their endpoints, and are arbitrarily combinable; i.e., any lower limit can be combined with any upper limit to form a single range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a particular parameter, it is understood that ranges of 60 to 110 and 80 to 120 are also contemplated. Furthermore, if 1 and 2 are listed as minimum range values ​​and 3, 4, and 5 are listed as maximum range values, the ranges 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5 are all contemplated. In this application, unless otherwise specified, a numerical range "a to b" is a shorthand representation of any combination of real numbers a to b, where a and b are both real numbers. For example, the numerical range "0-5" represents a list of all real numbers between "0-5" in this specification, and "0-5" is merely a shorthand representation of combinations of these numbers. Also, expressing a parameter as an integer ≧2 is equivalent to disclosing that this parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0028] Unless otherwise stated, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0029] Unless otherwise stated, all technical features and optional technical features of the present application can be combined with each other to form a new technical solution.

[0030] Unless otherwise specified, all steps in this application may be performed in order or randomly, and are preferably performed in order. For example, when the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed in order, or steps (b) and (a) performed in order. For example, when the method mentioned above may further include step (c), it means that step (c) may be added to the method in any order, and for example, the method may include steps (a), (b), and (c), or may include steps (a), (c), and (b), or may include steps (c), (a), and (b), etc.

[0031] Unless otherwise specified, the terms "comprise" and "include" used herein may be open-ended or closed-ended. For example, the terms "comprise" and "include" may indicate that other components not listed may be further included or included, or that only the listed components may be included or included.

[0032] Unless otherwise stated, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, an "A or B" condition is satisfied by either A being true (or present) and B being false (or absent), or A being false (or absent) and B being true (or present), or both A and B being true (or present).

[0033] To clearly explain the beneficial effects of the embodiments of the present application, in the context of the present specification, unless otherwise specified, a composite separator refers to a separator obtained by forming a coating layer on a base film by using the coating layer composition of the embodiments of the present application.

[0034] As described in the background art above, the range of applications of batteries is expanding, but the requirements for battery safety are also becoming higher. A battery cell generally includes a positive electrode sheet, a negative electrode sheet, and a separator, and the separator is located between the positive electrode sheet and the negative electrode sheet and serves to conduct ions and block electrons.

[0035] However, current separators generally use polyolefin films such as polyethylene and polypropylene, which pose the following problems: Polyolefin films have poor heat resistance, and polyethylene and polypropylene films experience severe shrinkage at temperatures of 130°C and 150°C, respectively, which can cause direct contact between the positive and negative electrode sheets, leading to short circuits and even thermal runaway, posing safety risks.

[0036] To address these issues, related technologies often fabricate ceramic coating layers on polyolefin films, thereby reducing the separator's thermal shrinkage and preventing direct contact between the positive and negative electrode sheets, thereby improving battery cell safety. However, a problem remains: the separator also serves as an ion conductor in the battery cell. While fabricating a heat-resistant coating layer on a polyolefin film can reduce the separator's thermal shrinkage to some extent, it significantly impacts the breathability of the polyolefin film, reducing the ion channels in the separator and resulting in reduced ion transport performance, which in turn increases polarization in the battery cell, degrading the battery's electrical performance, and reducing the battery's capacity retention. Furthermore, current heat-resistant coatings mainly use traditional ceramic materials such as boehmite, aluminum oxide, and silicon dioxide, which have high densities and therefore reduce the energy density of the battery cell.

[0037] In view of the above technical problems, embodiments of the present application provide a coating layer composition for use in a separator, which forms a heat-resistant coating layer on a base film. The coating layer composition contains porous phenolic resin microspheres, which have good heat resistance and can reduce the thermal shrinkage of the separator. Furthermore, due to their porous structure, the porous phenolic resin microspheres do not significantly affect the breathability of the separator, i.e., do not affect the ion transport performance of the separator, thereby improving battery safety and achieving high capacity retention. Furthermore, the density of the porous phenolic resin microspheres is lower than that of ceramic materials used in related art, so there is no significant impact on the energy density of the battery cell.

[0038] Coating layer composition for use in separator

[0039] According to a first aspect, an embodiment of the present application provides a coating layer composition for a separator, comprising porous phenolic resin microspheres and a binder, wherein the mass ratio of the binder to the porous phenolic resin microspheres is 1:1 to 1:20.

[0040] According to the present application, a coating layer composition containing porous phenolic resin microspheres and a binder is formed on a base film using the coating layer composition to obtain a composite separator, and the porous phenolic resin microspheres are then used as the skeleton of the coating layer. Phenolic resin is a type of synthetic resin obtained through an addition reaction and polycondensation reaction between a phenolic compound and an aldehyde compound. Like general polymer compounds, phenolic resins have basic properties of polymer compounds, such as a large molecular weight, a diverse molecular structure, curing properties, and pyrolysis and carbonization properties. Furthermore, due to the crosslinked network structure of phenolic resin and the large number of rigid benzene rings, the porous phenolic resin microspheres have excellent heat resistance, abrasion resistance, flame retardancy, and strength, and can maintain their structural integrity and dimensional stability even at very high temperatures. When the composite separator is heated, the base film shrinks, causing rapid contact and compression between the porous phenolic microspheres. However, due to the high heat resistance and strength of the porous phenolic microspheres, they are less likely to deform during compression. By applying a force to the base film in the opposite direction to the shrinkage, the thermal shrinkage rate of the base film can be significantly reduced, improving its heat resistance. Therefore, in battery cells using this composite separator, the composite separator has good deformation prevention ability at high temperatures, which reduces the possibility of direct contact between the positive and negative electrode sheets in the battery cell and causing a short circuit, thereby significantly improving the thermal safety of the battery cell.

[0041] Furthermore, Figure 1 shows an electron microscope image of the surface morphology of porous phenolic microspheres obtained in one embodiment of the present application, and Figure 2 shows an electron microscope image of the mechanical cross-section of porous phenolic microspheres obtained in one embodiment of the present application. As can be seen from these images, the porous phenolic microspheres have a porous structure, so even if the above-mentioned coating layer is formed on a base film, its breathability is not significantly affected. As can be seen, the role of the separator in a battery cell is to provide ion transport channels. The better the breathability of the separator, the more ion transport channels it can provide, i.e., the better the ion transport performance. Generally, a coating layer is formed on a base film, which may block some of the voids on the base film, resulting in a deterioration of ion transport performance. In this embodiment, the porous structure of the porous phenolic microspheres allows ions to pass through the pores in the microspheres, even if the original voids on the separator are blocked. Therefore, the breathability of a composite separator obtained using the above-mentioned coating layer composition is not significantly reduced compared to a base film.

[0042] At the same time, the porous structure of the porous phenolic microspheres allows the small pores to adsorb the electrolyte through capillary action, allowing the electrolyte to fill the pores of the porous phenolic microspheres and increasing the contact area between the separator and the electrolyte, which helps improve the wetting and liquid retention of the separator and provides sufficient ion channels, significantly improving the ion transport performance of the composite separator compared to conventional heat-resistant coatings. Therefore, battery cells using this composite separator exhibit small polarization during charge and discharge and high capacity retention.

[0043] Furthermore, due to their porous structure, the porous phenolic microspheres have a lower density than common phenolic microspheres, which can reduce the weight of the composite separator and improve the energy density of the battery cell.

[0044] The binder in the coating layer composition is primarily used to ensure stable adhesion between the porous phenolic microspheres and the base film, and between the porous phenolic microspheres themselves. Based on the explanation above for the porous phenolic microspheres' ability to reduce the thermal shrinkage of the base film, i.e., the porous phenolic microspheres exert a force on the base film in the direction opposite to the shrinkage direction. This stable adhesion between the porous phenolic microspheres and the base film plays a major role in enabling the porous phenolic microspheres to perform their function. Without a binder, the friction between the microspheres and the base film alone would be insufficient to reduce the thermal shrinkage of the base film. By adding a binder, the microspheres and the base film are bonded together through the binder, and the adhesive force is much greater than the friction force between the microspheres and the base film, allowing the coating layer to better reduce the thermal shrinkage of the base film. Furthermore, the strong adhesive force also ensures that the coating layer on the surface of the composite separator will not easily fall off, providing better stability and improving the safety of the battery cell.

[0045] In the present embodiment, the weight ratio of binder to porous phenolic resin microspheres is further limited to 1:1 to 1:20. It is understood that if the binder content is too high, the heat resistance and strength of typical binders are lower than that of phenolic resins, reducing the opposing force that the coating layer exerts on the base film in the direction of shrinkage, and thus failing to effectively reduce the thermal shrinkage of the base film. Furthermore, too much binder increases the difficulty of application and increases production costs. If the binder content is too low, the binder's function as described above is not effectively fulfilled, i.e., the adhesion between the microspheres and the base film is poor, reducing the opposing force that the coating layer exerts on the base film in the direction of shrinkage. This not only reduces the coating's ability to withstand the shrinkage, but also makes the coating unstable and prone to powder shedding, affecting the heat resistance and stability of the composite separator. Therefore, the mass ratio of the binder to the porous phenolic resin microspheres is controlled within the range of 1:1 to 1:20, and may be, for example, 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18, 1:19, 1:20, or any of the ranges above. Preferably, the mass ratio of the binder to the porous phenolic resin microspheres is 1:8 to 1:15.

[0046] In some embodiments, the binder comprises at least one of polyacrylic acid, polyacrylic ester, polyvinylidene fluoride, styrene butadiene rubber, and sodium carboxymethyl cellulose.

[0047] In the above embodiments, several specific binders are listed, but those skilled in the art can select one or more of them according to their implementation needs. Some of the binders listed above have good adhesive properties, which can stably bond the porous phenolic resin microspheres to the base film surface and improve the stability of the composite separator. In addition, some of the binders listed above also have good heat resistance and maintain strong adhesive properties even at high temperatures, thereby further improving the heat resistance of the composite separator.

[0048] The binder may include, but is not limited to, some of the materials listed above, and those skilled in the art may select any binder known in the prior art according to actual needs.

[0049] In some embodiments, the porous phenolic resin microspheres satisfy at least one of the following conditions: 1) The Dv50 particle size of the porous phenolic resin microspheres is 0.1 μm to 5 μm. 2) The average pore size of the porous phenolic resin microspheres is 10 nm to 50 nm. 3) The specific surface area of ​​the porous phenolic resin microspheres is 15 m 2 / g~280m 2 4) The total pore volume of the porous phenolic resin microspheres is 0.700 cm 3 / g~1.680cm 3 The composite separator thus obtained has better heat resistance or breathability, which is advantageous in improving the safety and capacity retention rate of a battery cell using the composite separator.

[0050] In the above embodiment, the relevant parameters of the porous phenolic microspheres are further defined, which results in a composite separator with higher heat resistance or air permeability, which is advantageous in improving the safety and capacity retention of a battery cell using the composite separator.

[0051] 1) The Dv50 particle size of the porous phenolic microspheres can be 0.1 μm to 5 μm. Generally, the smaller the particle size of the porous phenolic microspheres, the greater the number of microspheres per unit area of ​​the base film. Therefore, the greater the force acting against the shrinkage direction of the microspheres on the base film, resulting in a composite separator with better heat resistance. Furthermore, a smaller particle size allows for a thinner coating layer, while still ensuring the heat resistance of the composite separator, which is beneficial for improving the energy density of the battery cell. Therefore, generally, a composite separator with better heat resistance can be obtained by minimizing the Dv50 particle size of the porous phenolic microspheres. However, if the Dv50 particle size of the porous phenolic resin microspheres is too small, it will have a greater impact on the breathability of the composite separator. As can be seen, the smaller the particle size, the higher the bulk density of the coating layer and the lower the porosity of the coating layer. Furthermore, some of the porous phenolic resin microspheres will penetrate into the pores of the base film and block the pores. Although the porous structure can still provide channels for ion transmission, this will reduce the breathability of the base film to some extent. Furthermore, the porous phenolic resin microspheres located inside the pores of the base film will not be able to effectively apply a force to the base film in the direction opposite to the shrinkage direction, which will actually reduce the heat resistance of the composite separator.

[0052] Therefore, due to the excellent heat resistance and porous structure of the porous phenolic microspheres of the present invention, the Dv50 particle size of the porous phenolic microspheres can be smaller than that of ceramic materials using heat-resistant coatings in the prior art, thereby improving the energy density of battery cells while ensuring the heat resistance and breathability of the composite separator. Therefore, the Dv50 particle size of the porous phenolic microspheres is controlled to be 0.1 μm to 5 μm, and may be, for example, 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1.0 μm, 1.5 μm, 2.0 μm, 2.5 μm, 3.0 μm, 3.5 μm, 4.0 μm, 4.5 μm, 5.0 μm, or within any of the above ranges. More preferably, the Dv50 particle size of the porous phenolic resin microspheres is controlled to be 0.12 μm to 2 μm.

[0053] The Dv50 particle size of the porous phenolic resin microspheres of the present application has the meaning known in the art, i.e., the particle size of 50% of the particles in the volumetric particle size distribution is less than this value, and Dv50 can be measured by a method and apparatus known in the art, for example, GB / T 19077-2016 Particle Size Distribution Laser Diffraction Method, using a laser particle size analyzer (e.g., Malvern Mastersizer 2000E, UK).

[0054] 2) In the above embodiment, the average pore size of the porous phenolic resin microspheres is further limited. Generally, the smaller the average pore size of the porous phenolic resin microspheres, the more pronounced their capillary action. The resulting composite separator has better electrolyte salt wettability and liquid retention, which is advantageous for improving the ion transport performance of the composite separator. Furthermore, assuming a constant total pore volume, the smaller the average pore size, the better the heat resistance and rigidity of the porous phenolic resin microspheres, which is advantageous for improving the heat resistance of the composite separator. However, if the average pore size is too small, it is disadvantageous in increasing the total pore volume of the porous phenolic resin microspheres and also increases the production cost of the porous phenolic resin microspheres. Therefore, the average pore size of the porous phenolic resin microspheres is controlled to 10 nm to 50 nm. The resulting composite separator has good heat resistance and ion transport performance, which can improve the safety and capacity retention of battery cells. For example, the average pore size of the porous phenolic resin microspheres may be 10 nm, 12 nm, 14 nm, 16 nm, 20 nm, 22 nm, 24 nm, 26 nm, 28 nm, 30 nm, 32 nm, 34 nm, 36 nm, 38 nm, 40 nm, 42 nm, 44 nm, 46 nm, 48 nm, 50 nm, or within any range of the above numerical values. More preferably, the average pore size of the porous phenolic resin microspheres can be controlled to be 15 nm to 40 nm.

[0055] The average pore size of the porous phenolic resin microspheres in this application can be measured in accordance with GB / T 21650.2-2008, Determination of pore size distribution and porosity of solid materials by mercury intrusion and gas adsorption methods - Part 2: Analysis of mesopores and macropores by gas adsorption methods.

[0056] 3) In the above embodiment, the specific surface area of ​​the porous phenolic resin microspheres is further limited. It is understood that the specific surface area of ​​the porous phenolic resin microspheres is related to the particle size, pore size, and total pore volume. Generally, under other conditions, the smaller the particle size, the smaller the pore size, the larger the total pore volume, and the larger the specific surface area of ​​the porous phenolic resin microspheres. Through numerous experiments, the inventors have found that the specific surface area of ​​the porous phenolic resin microspheres is 15m 2 / g~280m 2 / g, the resulting composite separator has better heat resistance and ion transport performance, and the battery cell has better safety and higher capacity retention. For example, the specific surface area of ​​porous phenolic resin microspheres is 15 m 2 / g, 30m 2 / g, 45m 2 / g, 60m 2 / g, 80m 2 / g, 100m 2 / g, 110m 2 / g, 120m 2 / g, 130m 2 / g, 140m 2 / g, 150m 2 / g, 160m 2 / g, 170m 2 / g, 180m 2 / g, 190m 2 / g, 200m 2 / g, 210m 2 / g, 220m 2 / g, 230m 2 / g, 240m 2 / g, 250m 2 / g, 260m 2 / g, 270m 2 / g, 280m 2 / g, or any of the ranges defined above. More preferably, the specific surface area of ​​the porous phenolic resin microspheres is 60 m 2 / g~265m 2 / g.

[0057] The specific surface area of ​​the porous phenolic microspheres used in this application was measured using the following method: A specific surface area analyzer, model TRISTAR II 3020, was used to measure the specific surface area of ​​solid materials using the gas adsorption BET method in accordance with GB / T 19587-2004. 1. Pretreatment: An appropriate amount of sample was placed in a dedicated sample tube, heated, and evacuated for 2 hours. After cooling to room temperature, the total weight was measured and the mass of the sample tube was subtracted to obtain the sample mass. 2. Testing: The sample tube was placed in a workstation, and the amount of gas adsorbed on the solid surface at a constant temperature and under different adsorption pressures was measured. The monolayer adsorption amount of the sample was calculated based on the BET multilayer adsorption theory and its formula, and the specific surface area of ​​the solid sample per unit mass was then calculated. 3. The adsorbed gas was nitrogen, the adsorption pressure points were 0.05, 0.10, 0.15, 0.20, 0.25, and 0.30, and the test atmosphere was high-purity liquid nitrogen.

[0058] 4) In the above embodiment, the total pore volume of the porous phenolic resin microspheres is further limited. The larger the total pore volume of the porous phenolic resin microspheres, i.e., the higher the porosity, the more ion channels there are in the resulting composite separator, resulting in better ion transport performance and a higher capacity retention rate for the battery cell. However, if the total pore volume of the porous phenolic resin microspheres is too large, the heat resistance and strength of the porous phenolic resin microspheres will be reduced, leading to a reduction in the heat resistance of the composite separator and potentially a reduction in the safety of the battery cell. Therefore, the total pore volume of the porous phenolic resin microspheres is limited to 0.700 cm. 3 / g~1.680cm 3 / g, the composite separator can better combine its heat resistance and ion transport performance, and the battery cell has good safety and high capacity retention. For example, the total pore volume of the porous phenolic resin microspheres is 0.7 cm 3 / g, 0.75cm 3 / g, 0.8cm 3 / g, 0.85cm 3 / g, 0.9cm 3 / g, 0.95cm 3 / g, 1.0cm 3 / g, 1.05cm 3 / g, 1.1cm 3 / g, 1.15cm 3 / g, 1.2cm 3 / g, 1.25cm 3 / g, 1.3cm 3 / g, 1.35cm 3 / g, 1.4cm 3 / g, 1.45cm 3 / g, 1.5cm 3 / g, 1.55cm 3 / g, 1.6cm 3 / g, 1.68cm 3 / g, or any of the ranges defined above. More preferably, the total pore volume of the porous phenolic resin microspheres is 0.91 cm 3 / g~1.56cm 3 / g.

[0059] The total pore volume of the porous phenolic resin microspheres in this application was measured by the following method: a specific surface area analyzer, model TRISTAR II 3020, was used to directly test the total pore volume according to GB / T 21650.2-2008.

[0060] In some embodiments, the porous phenolic microspheres are obtained by reacting a phenolic compound with an aldehyde compound in a solvent in the presence of a catalytic amount of a phenol polycondensation reaction catalyst and a pore-forming amount of a pore-forming agent.

[0061] In the above embodiment, different types of porous phenolic resin microspheres can be obtained by selecting different phenolic compounds and aldehyde compounds, and different particle sizes, pore sizes, specific surface areas, or total pore volumes can be obtained by controlling the reaction conditions. This allows for a high degree of design flexibility, allowing suitable porous phenolic resin microspheres to be prepared according to actual needs.

[0062] For example, porous phenolic resin microspheres with different heat resistance or strength can be obtained by using different phenolic compounds and aldehyde compounds. Porous phenolic resin microspheres with different particle sizes can be obtained by controlling the reaction conditions, such as the ratio of the phenolic compound to the aldehyde compound, the stirring intensity during the reaction process, etc. The average pore size of the porous phenolic resin microspheres can be controlled by controlling the amount and type of pore-forming agent added or the reaction conditions, and at the same time, the specific surface area and total pore volume of the porous phenolic resin microspheres can be further controlled.

[0063] Additionally, porous phenolic microspheres with different performance parameters can also be purchased directly from commercial sources.

[0064] In some embodiments, the molar ratio of the phenolic hydroxyl groups in the phenol compound to the aldehyde groups in the aldehyde compound is 1:1.1 to 1:1.6.

[0065] In the above embodiment, controlling the molar ratio of the phenolic hydroxyl groups in the phenolic compound to the aldehyde groups in the aldehyde compound increases the number of initial crosslinking polymerization reaction sites in the reaction system, thereby advantageously controlling the particle size distribution of the porous phenolic resin microspheres, with a relatively more concentrated particle size, i.e., the resulting porous phenolic resin microspheres have a better dispersion, which is advantageous for obtaining porous phenolic resin microspheres with stable properties and ensures more stable performance of the coating layer composition. For example, the molar ratio of the phenolic hydroxyl groups in the phenolic compound to the aldehyde groups in the aldehyde compound may be 1:1.1, 1:1.15, 1:1.2, 1:1.25, 1:3, 1:1.35, 1:1.4, 1:1.45, 1:1.5, 1:1.55, 1:1.6, or within any range thereof. More preferably, the molar ratio of the phenolic hydroxyl groups in the phenol compound to the aldehyde groups in the aldehyde compound may be 1:1.1 to 1:1.4.

[0066] In some embodiments, the phenolic compound includes at least one of phenol, hydroquinone, resorcinol, catechol, cresol, and cardanol; the aldehyde compound includes formaldehyde and / or paraformaldehyde; the phenol polycondensation reaction catalyst is an alkaline substance and includes at least one of sodium hydroxide, aqueous ammonia, triethylamine, barium hydroxide, and aniline; and the pore-forming agent includes at least one of toluene, ethylene glycol, diethyl phthalate, octyl phthalate, and octadecanol.

[0067] In the above embodiment, the raw materials used for producing porous phenolic resin microspheres are specifically listed. However, the raw materials for producing the porous phenolic resin microspheres are inexpensive, readily available, and available in a wide variety, and can be selected according to actual needs, making them suitable for industrial production.

[0068] It should be noted that the above-mentioned phenolic compounds, aldehyde compounds, phenol polycondensation reaction catalysts, and pore-forming agents are not limited to those listed above, and those skilled in the art can select other types of phenolic compounds, aldehyde compounds, phenol polycondensation reaction catalysts, and pore-forming agents in the prior art according to actual needs.

[0069] As an example, the porous phenolic microspheres may be produced by the following method.

[0070] Phenol compounds, aldehyde compounds, phenol polycondensation catalysts and pore-forming agents are added to a solvent to obtain a reaction system, which is reacted for 3 to 8 hours under heating and stirring conditions, and the pH of the reaction system is adjusted to 2 to 6. The reaction system is then heated and reacted for 0.5 to 2 hours, and then cooled to room temperature with stirring.

[0071] The reaction mixture is filtered, washed and dried to obtain porous phenolic resin microspheres.

[0072] It is understood that the above method is only an example and the porous phenolic microspheres may be produced by other methods known in the art.

[0073] For example, the total mass percentage content of the phenolic compounds and aldehyde compounds in the reaction system is 21% to 26%, the mass percentage content of the phenol polycondensation reaction catalyst in the reaction system is 0.1% to 1%, the mass percentage content of the pore-forming agent in the reaction system is 5% to 10%, and the remainder is the solvent, which may be water.

[0074] For example, the heating temperature during heating and stirring is 70°C to 100°C.

[0075] In some embodiments, the coating layer composition further comprises a dispersing agent, which may be selected from the group consisting of water, dimethylformamide (DMF), diethylformamide, dimethylacetamide (DMAc), N-methylpyrrolidone (NMP), methanol, ethanol, 1-propanol, 2-propanol (isopropanol), 1-butanol (n-butanol), 2-methyl-1-propanol (isobutanol), 2-butanol (sec-butanol), 1-methyl-2-propanol (tert-butanol), pentanol, hexanol, heptanol, or octanol, as well as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,5-pentanediol, hexanediol, glycerin, trimethylene glycol, methyl methyl acrylate, methyl acrylate, methyl acrylate (MMA), ... At least one of glycols such as ethylolpropane, pentaerythritol, sorbitol, ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, tetraethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, triethylene glycol monoethyl ether, tetraethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monobutyl ether, acetone, methyl ethyl ketone, methyl propyl ketone, cyclopentanone, ethyl acetate, γ-butyrolactone, and ε-propiolactone may be included.

[0076] In some embodiments, the solids content in the coating layer composition may be 10% to 50%.

[0077] In some embodiments, other additives may be included in the coating layer composition, such as antifoaming agents, wetting agents, emulsifiers, suspending agents, etc. One skilled in the art can select additives as needed.

[0078] Method for producing coating layer composition used in separator The present application further provides a method for producing a coating layer composition for a separator, which includes the following steps: dispersing porous phenolic resin microspheres and a binder in a dispersant, thereby obtaining a coating layer composition for a separator.

[0079] The specific types and amounts of the porous phenolic resin microspheres, binder and dispersant can be selected according to any of the embodiments of the first aspect.

[0080] Composite Separator According to a second aspect, the present application provides a composite separator including a base film and a coating layer formed on at least one surface of the base film by the coating layer composition according to any one of the embodiments of the first aspect.

[0081] According to the present application, the composite separator includes a coating layer formed from the coating layer composition of any of the embodiments of the first aspect, and therefore, as will be appreciated, the composite separator has the beneficial effects of the first aspect.

[0082] In any embodiment of the present application, the type of base film is not limited, and those skilled in the art can select a known separator in the prior art as the base film according to actual needs. For example, a monolayer polyolefin separator or a multilayer polyolefin separator can be used as the base film. The monolayer polyolefin separator may include at least one of a polyethylene separator and a polypropylene separator, and the multilayer polyolefin separator may include at least one of a polypropylene-polyethylene-polypropylene separator and a polypropylene-polyethylene separator.

[0083] In some embodiments, the areal density of the coating layer is 0.1 g / m 2 ~5g / m 2 is.

[0084] In the above embodiment, the porous phenolic resin microspheres in the coating layer have good heat resistance and strength, and their density is low. Therefore, compared with a typical ceramic coating layer, the coating layer can provide good heat resistance to the composite separator even under conditions of low areal density. The low areal density also improves the breathability of the composite separator, thereby providing not only good safety but also a higher capacity retention rate for the battery cell. At the same time, the energy density of the battery cell can be effectively improved. If the areal density of the coating layer is too low, the heat resistance of the composite separator cannot be guaranteed. Therefore, the areal density of the coating layer is set to 0.1 g / m. 2 ~5g / m 2 For example, the surface density of the coating layer is controlled within the range of 0.1 g / m 2 , 0.2g / m 2 , 0.3 g / m 2 , 0.4g / m 2 , 0.5g / m 2 , 0.6g / m 2 , 0.7g / m 2 , 0.8g / m 2 , 0.9g / m 2 , 1g / m 2 , 1.2g / m 2 , 1.4g / m 2 , 1.6g / m 2 , 1.8g / m 2 , 2g / m 2 , 2.2g / m 2 , 2.4g / m 2 , 2.6g / m 2 , 2.8g / m 2 , 3g / m 2 , 3.5g / m 2 , 4g / m 2 , 4.5g / m 2 , 5g / m 2 More preferably, the surface density of the coating layer is 1 g / m 2 ~4g / m 2 may be.

[0085] In some embodiments, the composite separator satisfies 1.25≦D / d≦62.5, where D is the Dv50 particle size of the porous phenolic microspheres and d is the average pore size of the base film.

[0086] In the above embodiment, the relationship between the Dv50 particle size of the porous phenolic microspheres and the average pore size of the base film is specifically defined. Through numerous experiments, the inventors have found that the resulting composite separator has good heat resistance and breathability. Compared with conventional ceramic coatings, the D / d value can be reduced. This indicates that the porous phenolic microspheres have good heat resistance and porous structure, so that the composite separator can meet the heat resistance and breathability requirements even with a small number of porous phenolic microspheres in the coating. This allows for a lighter coating process, reduces the overall weight and thickness of the composite separator, and improves the energy density of the battery cell. The value of D / d may be 1.25, 1.5, 2, 2.5, 3, 3.5, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 22, 24, 26, 28, 30, 35, 40, 45, 50, 55, 60, 62.5, or a range consisting of any of the foregoing values. More preferably, the composite separator satisfies 1.5≦D / d≦25.

[0087] Battery cell According to a third aspect, the present application provides a battery cell including the composite separator of any embodiment of the second aspect.

[0088] According to the present application, the battery cell includes the composite separator of any embodiment of the second aspect, and therefore, it will be understood that the battery cell has the beneficial effects of the second aspect.

[0089] Generally, a battery cell further includes a positive electrode sheet, a negative electrode sheet, and an electrolyte. During the charge and discharge process of the battery, active ions are inserted and removed between the positive electrode sheet and the negative electrode sheet. The electrolyte serves to conduct ions between the positive electrode sheet and the negative electrode sheet.

[0090] [Positive electrode sheet] In some embodiments, the positive electrode sheet includes a positive electrode current collector and a positive electrode film layer provided on at least one surface of the positive electrode current collector and including the positive electrode active material according to the first aspect of the present application.

[0091] As an example, the positive electrode current collector has two surfaces facing each other in the thickness direction thereof, and the positive electrode film layer is provided on one or both of the two facing surfaces of the positive electrode current collector.

[0092] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. Examples of the metal foil include aluminum foil. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base layer. The composite current collector may be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0093] In some embodiments, the positive electrode active material may be a positive electrode active material for batteries known in the art. For example, the positive electrode active material may include at least one of a lithium-containing phosphate with an olivine structure, a lithium transition metal oxide, and a modified compound thereof. However, the present application is not limited to these materials, and other conventional materials that can be used as a positive electrode active material for a battery may also be used. These positive electrode active materials may be used alone or in combination of two or more. Here, examples of lithium transition metal oxides include lithium cobalt oxide (e.g., LiCoO), lithium nickel oxide (e.g., LiNiO), lithium manganese oxide (e.g., LiMnO, LiMnO), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, and lithium nickel cobalt manganese oxide (e.g., LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM 333 (may be abbreviated as "LiNi") 0.5 Co 0.2 Mn 0.3 O2(NCM 523 (may be abbreviated as "LiNi") 0.5 Co 0.25 Mn 0.25 O2(NCM 211 (may be abbreviated as "LiNi") 0.6 Co 0.2 Mn 0.2 O2(NCM 622 (may be abbreviated as "LiNi") 0.8 Co 0.1 Mn 0.1 O2(NCM 811 ), lithium nickel cobalt aluminum oxide (e.g., LiNi 0.85 Co 0.15 Al 0.05O2) and modified compounds thereof, etc. The lithium-containing phosphate having an olivine structure may include, but is not limited to, for example, at least one of lithium iron phosphate (e.g., LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (e.g., LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite material of lithium manganese iron phosphate and carbon.

[0094] In some embodiments, the positive electrode film layer may further include a binder, such as at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0095] In some embodiments, the positive electrode film layer may further include a conductive agent, for example, at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0096] In some embodiments, the positive electrode sheet can be manufactured by the following method: Components for manufacturing the positive electrode sheet, such as a positive electrode active material, a conductive agent, a binder, and any other components, are dispersed in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode paste, which is then applied to a positive electrode current collector, followed by processes such as drying and cold pressing, to obtain a positive electrode sheet.

[0097] [Negative electrode sheet] The negative electrode sheet includes a negative electrode active material and includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector.

[0098] As an example, the negative electrode current collector has two surfaces facing each other in the thickness direction thereof, and the negative electrode film layer is provided on one or both of the two facing surfaces of the negative electrode current collector.

[0099] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. The metal foil may be, for example, a copper foil. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0100] In some embodiments, the negative electrode active material may be a battery negative electrode active material known in the art. For example, the negative electrode active material may include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, a silicone-based material, a tin-based material, and lithium titanate. The silicone-based material may be selected from at least one of a silicone element, a silicone oxide, a silicone carbon composite, a silicone nitrogen composite, and a silicone alloy. The tin-based material may be selected from at least one of a tin element, a tin oxide, and a tin alloy. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery negative electrode active material may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0101] In some embodiments, the negative electrode film layer optionally further comprises a binder, which may be selected from at least one of styrene butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0102] In some embodiments, the negative electrode film layer further optionally includes a conductive agent, which may be selected from at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0103] In some embodiments, the negative electrode film layer further optionally includes other additives, such as a thickener (eg, sodium carboxymethylcellulose (CMC-Na)).

[0104] In some embodiments, the negative electrode sheet can be manufactured in the following manner: Components for manufacturing the negative electrode sheet, such as a negative electrode active material, a conductive agent, a binder, and any other components, are dispersed in a solvent (e.g., deionized water) to form a negative electrode paste, which is then applied to a negative electrode current collector, dried, cold-pressed, and other processes to obtain a negative electrode sheet.

[0105] [Electrolyte] The electrolyte serves to conduct ions between the positive electrode sheet and the negative electrode sheet. The present application does not particularly limit the type of electrolyte, and it can be selected as needed. For example, the electrolyte may be liquid, gel, or completely solid.

[0106] In some embodiments, the electrolyte uses an electrolytic solution, which includes an electrolyte salt and a solvent.

[0107] In some embodiments, the electrolyte salt may be chosen from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoro(oxalato)borate, lithium bis(oxalato)borate, lithium difluorobis(oxalato)phosphate, and lithium tetrafluoro(oxalato)phosphate.

[0108] In some embodiments, the solvent may be chosen from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, ethyl methyl sulfone, and diethyl sulfone.

[0109] In some embodiments, the electrolyte solution may further optionally contain additives, such as a negative electrode film-forming additive, a positive electrode film-forming additive, or an additive that can improve specific battery characteristics, such as an additive that improves the overcharge characteristics of the battery or an additive that improves the high-temperature or low-temperature characteristics of the battery.

[0110] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the composite separator can be fabricated into an electrode assembly via a winding or lamination process.

[0111] In some embodiments, the battery cell may include a housing material, which is used to encapsulate the electrode assembly and electrolyte.

[0112] In some embodiments, the battery cell exterior may be a hard case, such as a hard plastic case, an aluminum case, or a steel case. The battery cell exterior may be a soft pack, such as a pouch-type soft pack. The soft pack may be made of plastic, such as polypropylene, polybutylene terephthalate, or polybutylene succinate.

[0113] The present application does not particularly limit the shape of the battery cell, and it may be cylindrical, rectangular, or any other shape. For example, Figure 3 shows an example of a rectangular battery cell 5.

[0114] In some embodiments, referring to FIG. 4 , the exterior material may include a housing 51 and a cover plate 53. Here, the housing 51 may include a base plate and a side plate connected to the base plate, and the base plate and the side plate surround and form a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover plate 53 may cover the opening and seal the receiving cavity. The positive electrode sheet, the negative electrode sheet, and the separator may be formed into an electrode assembly 52 by a winding process or a stacking process. The electrode assembly 52 is packaged in the receiving cavity. An electrolyte is impregnated in the electrode assembly 52. ​​The number of electrode assemblies 52 included in the battery cell 5 may be one or more, and this can be selected by those skilled in the art according to specific actual requirements.

[0115] battery According to a fourth aspect, the present application provides a battery comprising a battery cell according to any embodiment of the third aspect.

[0116] According to the present application, the battery cells can be assembled into a battery, and one embodiment of the present application provides a battery including a housing and the above-mentioned battery cells, the battery cells being housed within the housing.

[0117] The number of battery cells included in the battery may be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery.

[0118] Furthermore, in the above-described battery, a plurality of battery cells are assembled to form a battery module. FIG. 5 shows an example of a battery module 4. Referring to FIG. 5, in the battery module 4, a plurality of battery cells 5 can be arranged in sequence along the length of the battery module 4. Of course, any other arrangement is also possible. The plurality of battery cells 5 can also be fixed by fasteners.

[0119] Optionally, the battery module 4 may further include an outer case having an accommodating space for accommodating the plurality of battery cells 5.

[0120] 6 and 7 show an example of a battery 1. Referring to FIGS. 6 and 7, the battery 1 may include a battery case and a plurality of battery modules 4 installed in the battery case. The battery case includes an upper housing 2 and a lower housing 3, and the upper housing 2 can be fitted over the lower housing 3 to form a sealed space for accommodating the plurality of battery modules 4. The plurality of battery modules 4 may be arranged in the battery case in any manner.

[0121] The battery may be a secondary battery or a lithium battery.

[0122] power consumption equipment According to a fifth aspect, the present application provides a power consuming device comprising at least one of the battery cell of any of the embodiments of the third aspect or the battery of any of the embodiments of the fourth aspect.

[0123] The present application further provides a power consuming device including a battery cell or battery according to the present application. The battery cell or battery may be used as a power source for the power consuming device or as an energy storage element for the power consuming device. The power consuming device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), trains, ships, satellites, energy storage systems, etc.

[0124] The power consumption device can be selected as the battery cell or battery according to its usage requirements.

[0125] 8 shows an example of a power consuming device, such as a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle.

[0126] Other examples of the device may be a mobile phone, a tablet computer, a laptop computer, etc. Such devices are generally required to be lightweight and thin, and can use a battery cell as a power source.

[0127] Example Examples of the present application are described below. The examples described below are illustrative and are intended only to explain the present application and should not be understood as limitations on the present application. If specific techniques or conditions are not specified in the examples, they will be carried out according to techniques or conditions described in literature in the field or according to product specifications. If the manufacturer of the reagents or equipment used is not specified, they are all commercially available general products.

[0128] Preparation of porous phenolic resin microspheres: Add phenolic compounds, aldehyde compounds, catalysts, pore-forming agents, and water in a certain proportion to a three-necked flask equipped with a mechanical stirrer and reflux condenser. Start stirring and heat to 90°C. Stir for 4 hours to disperse the mixture. Adjust the pH of the system to 2-3, and continue heating for 1 hour to allow the reaction to proceed. Then stop heating and stir and cool to room temperature.

[0129] The reaction product is filtered, washed with water until neutral, and dried to obtain porous phenolic resin microspheres.

[0130] According to conventional methods, phenolic resin porous microspheres with different particle sizes, average pore sizes, specific surface areas, and total pore volumes can be obtained by controlling the types and amounts of the phenolic compound, aldehyde compound, catalyst, and pore-forming agent in the reaction system, or by controlling the reaction conditions.

[0131] Example 1-1 (1) Manufacturing of composite separators A commercially available PE polymer microporous film (obtained from Zhuoga Electronics Technology Co., Ltd.) with a thickness of 7 μm and an average pore size of 80 nm was used as the substrate. A polyacrylic acid binder and porous phenolic resin microspheres (1:10 by mass, totaling 150 g) were added to 850 g of deionized water and stirred to obtain a paste. The paste was then coated on the substrate and dried in an oven. The coating density of the binder and porous phenolic resin microspheres on the substrate was 2 g / m. 2 and then wound up to finally obtain a composite separator.

[0132] The relevant manufacturing parameters of the porous phenolic resin microspheres and their Dv50 particle size, average pore size, specific surface area and total pore volume are shown in Table 1.

[0133] (2) Manufacturing of positive electrode sheets A positive electrode paste was prepared by thoroughly stirring and homogeneously mixing polyvinylidene fluoride (PVDF), lithium iron phosphate (LFP), conductive carbon black, and N-methylpyrrolidone (NMP) in a mass ratio of 1.2:58.38:0.42:40. The positive electrode paste was prepared at a concentration of 200 g / m. 2 The coated aluminum foil is then dried, cold pressed, and cut to obtain a positive electrode sheet.

[0134] (3) Manufacturing of negative electrode sheets Artificial graphite, acetylene black as a conductive agent, styrene butadiene rubber (SBR) as a binder, and sodium carboxymethyl cellulose (CMC-Na) as a thickener were added to deionized water in a mass ratio of 96.2:1.0:1.6:1.2, and the mixture was thoroughly stirred to homogeneously mix, producing a negative electrode paste (solid content 63%). 2 After coating the copper foil of the negative electrode current collector with the amount of the support, the negative electrode sheet is obtained by drying, cold pressing, and cutting.

[0135] (4) Electrolyte production At 25°C, ethylene carbonate (EC), methyl ethyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1 to obtain a mixed solvent, and then LiPF6 was dissolved in the mixed solvent to obtain an electrolyte solution with a LiPF6 concentration of 1 mol / L.

[0136] (5) Secondary battery manufacturing The positive electrode sheet, composite separator, and negative electrode sheet are stacked in this order, wound, and cold press-molded (during which the separator and polar sheet are bonded together) to obtain a cell. The cell is then placed in an exterior packaging, the above-prepared electrolyte solution is added, and a secondary battery is obtained through processes such as sealing, leaving, chemical conversion, and aging.

[0137] Examples 1-2 to 1-36 are almost the same as Example 1-1, with some different parameters as shown in Table 1.

[0138] Comparative Example 1-1 This was almost the same as Example 1-1, except that a commercially available PE polymer microporous film with a thickness of 7 μm and an average pore size of 80 nm was used as the separator of the secondary battery.

[0139] Comparative Example 1-2 This example is almost the same as Example 1-1, except that the composite separator is different. A composite separator made of porous phenolic resin microspheres and aluminum oxide with a Dv50 of 1 μm was used as the separator for the secondary battery.

[0140] Examples 2-1 to 2-10, Comparative Example 2-1, Comparative Example 2-2 and Example 1-7 are almost the same, with some different parameters as shown in Table 2.

[0141] Exam section 1. Separator heat shrinkage test Sample preparation: The separator manufactured above is punched out into samples 50 mm wide and 100 mm long using a press, and five parallel samples are placed on A4 paper and fixed in place. The A4 paper with the samples attached is then placed on a piece of cardboard 1 mm to 5 mm thick.

[0142] Sample test: The temperature of the blast oven is set to 150°C. After the temperature reaches the set temperature and stabilizes for 30 minutes, an A4 sheet of paper placed on top of the cardboard is placed in the blast oven, timing begins, and after the set time (1 hour in this case) has elapsed, the length and width of the separator are recorded and the values ​​are recorded as a and b respectively.

[0143] Calculation of heat shrinkage: Machine direction (MD) heat shrinkage = [(100-a) / 100] x 100%, transverse direction (TD) heat shrinkage = [(50-b) / 50] x 100%, and the average value of five parallel samples is taken as the test result.

[0144] 2.Method of measuring air permeability The separator was cut into a 5cm square and tested using a gas permeability tester. A pressure of 1.21kPa was applied to the separator, and 100ml of gas was passed through the separator at a 6.45cm diameter. 2The time required for the gas to permeate the separator is tested and calculated in s / 100 mL to obtain its air permeability value.

[0145] 3. Secondary battery capacity retention rate test At 25°C, charge the battery to 4.2V at a constant current of 1 / 3C, then charge it at a constant voltage of 4.2V until the current reached 0.05C, leave it for 5 minutes, and discharge it to 2.8V at 1 / 3C. The resulting capacity is the initial capacity C0. The above steps are repeated, and the discharge capacity C1000 of the secondary battery after 1000 cycles is recorded at the same time. The capacity retention rate of the secondary battery after 1000 cycles P1000 = C1000 / C0 × 100%.

[0146] The test results are shown in Table 1 (Table 1A, Table 1B) and Table 2.

[0147] [Table 1A]

[0148] [Table 1B]

[0149] Note: "\" in Table 1 indicates that the parameter is not included.

[0150] [Table 2]

[0151] As can be seen from Table 1, comparing each example with each comparative example, the composite separators obtained in each example had a smaller heat shrinkage rate and significantly improved capacity retention rates of the secondary batteries. In Comparative Example 1-1, a polyethylene base film was directly used as the separator for the secondary battery, which had low heat resistance and therefore a high heat shrinkage rate, resulting in poor safety for the secondary battery. Furthermore, although no coating layer was formed on the surface and good breathability was achieved, heat generation during the secondary battery cycling process was unavoidable, preventing the separator from maintaining a stable structure, resulting in a low capacity retention rate. In Comparative Example 1-2, aluminum oxide with a Dv50 particle size of 1 μm was used instead of the composite separator made of porous phenolic resin microspheres. The thermal shrinkage rate was lower than that of Comparative Example 1-1, but the effect of the reduction was not significant. The possible reasons for this are the poor film-forming properties of aluminum oxide. Although aluminum oxide itself has good heat resistance, it does not significantly improve the heat resistance of the separator. Furthermore, since it does not have a porous structure, its air permeability is significantly lower than that of the examples and Comparative Example 1-1, resulting in a decrease in ion transport channels, increased polarization, and a low capacity retention rate of the secondary battery.

[0152] As can be seen from a comparison of Examples 1-1 to 1-20, the parameters of the porous phenolic resin microspheres have a certain effect on the heat resistance and breathability of the composite separator, which in turn affects the safety and capacity retention rate of the secondary battery. The porous phenolic resin microspheres have a Dv50 particle size of 0.1 μm to 5 μm, an average pore size of 10 nm to 50 nm, and a specific surface area of ​​15 m 2 / g~280m 2 / g, total pore volume 0.700 cm 3 / g to 1.680cm 3 When any one of the above conditions is satisfied, the obtained composite separator has good heat resistance and good air permeability, and the secondary battery has good safety and high capacity retention. Preferably, the porous phenolic resin microspheres have a Dv50 particle size of 0.12 μm to 2 μm, an average pore size of 15 nm to 40 nm, and a specific surface area of ​​60 m 2 / g~m 2 / g, total pore volume 0.910 cm 3 / g~1.560cm 3 / g satisfies the above condition, the heat resistance and breathability of the obtained composite separator are better, and the secondary battery has better safety and a higher capacity retention rate.

[0153] As can be seen from a comparison of Examples 1-21 to 1-28 and Example 1-7, the surface density of the coating layer has a certain effect on the heat resistance and breathability of the composite separator, which in turn affects the safety and capacity retention rate of the secondary battery. 2 ~5g / cm 2 When the surface density of the coating layer is 1 g / cm, the heat resistance and breathability of the obtained composite separator are good, and the secondary battery has good safety and a high capacity retention rate. 2 ~4g / cm 2 When the temperature is 100°C, the heat resistance and breathability of the obtained composite separator are better, and the secondary battery has better safety and a higher capacity retention rate.

[0154] As can be seen from a comparison of Examples 1-29 to 1-32 and 1-7, the molar ratio of phenolic hydroxyl groups to aldehyde groups in the raw materials used to produce the porous phenolic resin microspheres has a certain effect on the heat resistance and breathability of the composite separator, thereby affecting the safety and capacity retention of the secondary battery. When the molar ratio of phenolic hydroxyl groups to aldehyde groups is 1:1.1 to 1:1.6, the resulting composite separator has good heat resistance and breathability, and the secondary battery has good safety and a high capacity retention. Preferably, when the molar ratio of phenolic hydroxyl groups to aldehyde groups is 1:1.1 to 1:1.4, the resulting composite separator has better heat resistance and breathability, and the secondary battery has better safety and a high capacity retention.

[0155] As can be seen from a comparison of Examples 1-33 to 1-36 and 1-7, the phenolic compounds and aldehyde compounds in the raw materials for producing the porous phenolic resin microspheres have a small effect on the heat resistance and air permeability of the composite separator, and all of them have good heat resistance and air permeability, and the safety and capacity retention rate of the secondary battery are good.

[0156] The possible reasons for the above results are explained in the summary of the invention above, and will not be explained here.

[0157] Table 2 shows that the composite separators obtained in each Example and Comparative Example had smaller heat shrinkage and better air permeability, resulting in better secondary battery capacity retention. In Comparative Example 2-1, the binder content was too high, resulting in a small porosity of the coating layer and poor heat resistance, resulting in a large heat shrinkage and air permeability. Consequently, the composite separator had poor heat resistance and air permeability, resulting in a low secondary battery capacity retention. In Comparative Example 2-2, the binder content was too low, resulting in an inability to stably bond the porous phenolic resin microspheres to the surface of the base film, preventing effective reduction in the heat shrinkage of the base film. At the same time, the excessive microspheres affected the air permeability of the composite separator, reducing its stability and resulting in a low secondary battery capacity retention.

[0158] As can be seen from a comparison of Examples 2-1, 2-2, and 1-7, the types of common binders have a small effect on the heat resistance and breathability of the composite separator, and all of them have good heat resistance and breathability, and the safety and capacity retention rate of the secondary battery are good.

[0159] As can be seen from a comparison of Examples 2-1, 2-3, and 2-9, the mass ratio of the binder to the porous phenolic resin microspheres has a certain effect on the heat resistance and breathability of the composite separator, which in turn affects the safety and capacity retention of the secondary battery. When the mass ratio of the binder to the porous phenolic resin microspheres is 1:1 to 1:20, the resulting composite separator has good heat resistance and breathability, and the secondary battery has good safety and a high capacity retention. Preferably, when the mass ratio of the binder to the porous phenolic resin microspheres is 1:8 to 1:15, the resulting composite separator has better heat resistance and breathability, and the secondary battery has better safety and a high capacity retention.

[0160] The possible reasons for the above results are explained in the summary of the invention above, and will not be explained here.

[0161] It should be noted that the present application is not limited to the above-described embodiments. The above-described embodiments are merely examples, and any embodiment that has substantially the same configuration as the technical idea and achieves the same effects within the scope of the technical solution of the present application is included within the technical scope of the present application. It should be noted that various modifications that a person skilled in the art can make to the embodiments and other forms formed by combining some of the components of the embodiments are also included within the scope of the present application, as long as they do not deviate from the spirit of the present application.

Claims

1. A coating layer composition for use in a separator, comprising porous phenolic resin microspheres and a binder, The coating layer composition for use in a separator has a weight ratio of the binder to the porous phenolic resin microspheres of 1:1 to 1:

20.

2. 10. The coating layer composition of claim 1, wherein the binder comprises at least one of polyacrylic acid, polyacrylic ester, polyvinylidene fluoride, styrene butadiene rubber, and sodium carboxymethyl cellulose.

3. The porous phenolic resin microspheres are Condition 1) the Dv50 particle size of the porous phenolic resin microspheres is 0.1 μm to 5 μm; Condition 2) the average pore size of the porous phenolic resin microspheres is 10 nm to 50 nm; The specific surface area of ​​the porous phenolic resin microspheres is 15 m ２ / g~280m ２ / g) and The total pore volume of the porous phenolic resin microspheres is 0.700 cm ３ / g ~ 1.680 cm ３ The coating layer composition according to claim 1 or 2, which satisfies at least one of the conditions 4) above:

4. The porous phenolic resin microspheres are Condition 1) the Dv50 particle size of the porous phenolic resin microspheres is 0.12 μm to 2 μm; Condition 2) the average pore size of the porous phenolic resin microspheres is 15 nm to 40 nm; The specific surface area of ​​the porous phenolic resin microspheres is 60 m ２ / g~265m ２ / g) and The total pore volume of the porous phenolic resin microspheres is 0.910 cm ３ / g ~ 1.560 cm ３ The coating layer composition according to any one of claims 1 to 3, which satisfies at least one of the conditions 4) above: / g.

5. The coating layer composition according to any one of claims 1 to 4, wherein the porous phenolic resin microspheres are obtained by reacting a phenolic compound with an aldehyde compound in a solvent in the presence of a catalytic amount of a phenol polycondensation reaction catalyst and a pore-forming amount of a pore-forming agent.

6. 6. The coating layer composition according to claim 5, wherein the molar ratio of the phenolic hydroxyl groups in the phenolic compound to the aldehyde groups in the aldehyde compound is 1:1.1 to 1:1.

6.

7. the phenolic compound includes at least one of phenol, hydroquinone, resorcinol, catechol, cresol, and cardanol; the aldehyde compound includes formaldehyde and / or paraformaldehyde, the phenol polycondensation reaction catalyst is an alkaline substance and includes at least one of sodium hydroxide, aqueous ammonia, triethylamine, barium hydroxide, and aniline; 7. The coating layer composition of claim 5 or 6, wherein the pore former comprises at least one of toluene, ethylene glycol, diethyl phthalate, octyl phthalate, and octadecanol.

8. A base film; a coating layer formed on at least one surface of the base film using the coating layer composition according to any one of claims 1 to 7.

9. The surface density of the coating layer is 0.1 g / m ２ ~5g / m ２ 9. The composite separator of claim 8, wherein:

10. 1.25≦D / d≦62.5 is satisfied, however, D is the Dv50 particle size of the porous phenolic resin microspheres, 10. The composite separator according to claim 8 or 9, wherein d is the average pore size of the base film.

11. The composite separator according to any one of claims 8 to 10, which satisfies 1.5≦D / d≦25.

12. A battery cell comprising the composite separator of any one of claims 8 to 11.

13. A battery comprising the battery cell of claim 12.

14. 14. A power consuming device comprising at least one of the battery cell of claim 12 or the battery of claim 13.

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