Porous membranes filled with nanoparticles and related methods

Abstract

The method for changing the surface energy of nano ceramic particles to be similar to the surface energy of polymer materials, first, the nano ceramic particles are pre-treated on the surface; then the nano ceramic particles are coated with wax on the surface; after the double surface treatment of the surface pre-treatment and the surface coating with wax, the coating molecules on the surface of the nano ceramic particles become reactive end and non-polar end, the reactive end is combined with the surface of the nano particles, and the non-polar end is combined with the polymer material; the non-polar end is a hydrocarbon with at most 20 carbon atoms, containing a single bond or a double bond capable of undergoing a reaction to add one or more increasing hydrocarbon functional groups as a side chain; the non-polar end surrounds the outside of the ceramic nano particles, increasing the volume occupied by the ceramic nano particles; the hydrocarbon tail surrounding the ceramic nano particles has a similar surface energy to the polymer material, so that the ceramic nano particles are better dispersed and mixed into the polymer material, and the ceramic nano particles are prevented from gathering into agglomerates.

Description

[0001] This application is a divisional application. The parent application number is 202111173162.1, the filing date is September 18, 2014, and the invention title is "Porous Membrane Filled with Nanoparticles and Related Methods". This divisional application is filed in response to the unity of invention issue raised in the First Office Action issued on October 13, 2022, regarding the parent application 202111173162.1. Related applications

[0002] This application claims priority and benefit to co-pending U.S. provisional patent application No. 61 / 879,175, filed September 18, 2013, the contents of which are incorporated herein by reference. Technical Field

[0003] This invention relates to membranes filled / filled with particles, microporous membranes filled / filled with surface-treated (or coated) nanoparticles, battery separators, and related methods of manufacturing and / or using them. Background Technology

[0004] Battery separators containing filled and coated ceramic particles for secondary lithium-ion batteries are known, for example, those described in their respective U.S. Patents US7,790,320 and US6,432,586, which are hereby incorporated by reference. These separators are believed to improve the safety of secondary lithium-ion batteries by, for example, blocking dendrites, preventing short circuits, and enhancing the heat resistance and stiffness (strength and structure) of the polymer (e.g., polyolefin) layer. Typically, prior art particles comprise fairly large (some with particle sizes >1 micrometer) particles such as SiO2, TiO2, Al2O3, BaSO4, and CaCO3. However, these ceramic particles can be difficult to load and disperse into polymer materials due to the difference in surface energy between the particles and the polymer resin material. These problems become even more severe as particle sizes move from the micrometer to the nanometer range, because the surface energy of the particles increases even more significantly.

[0005] Therefore, the problem is to load and disperse at least some ceramic particles into the polymer resin used to form a membrane (e.g., a battery separator). Summary of the Invention

[0006] According to at least selected embodiments, the membrane of the present invention comprises a porous membrane or layer made of a polymer material in which surface-treated (or coated) particles (or ceramic particles) with an average particle size of less than about 1 micrometer are dispersed. The polymer material may be selected from polyolefins, polyamides, polyesters, copolymers thereof, and combinations thereof. The particles may be selected from boehmite (AlOOH), SiO2, TiO2, Al2O3, BaSO4, CaCO3, BN, and combinations thereof. The surface treatment (or coating) on ​​the particles or nanoparticles may be molecules having reactive and non-polar ends, the reactive ends being bonded to the surface of the particles or nanoparticles, and the non-polar ends being bonded to the polymer material. The surface coating preferably alters the surface energy of the particles to be similar to the surface energy of the polymer material. Having similar surface energies allows for better mixing or blending of the nanoparticles and the polymer material. In the case of porous polymer materials used as battery separator membranes, the separator of the present invention has already been prepared using additional optional inventive steps in the preparation of the ceramic nanoparticle and polymer resin mixture. Because surface-treated ceramic nanoparticles are prone to aggregation and agglomeration, further treatment is recommended to eliminate this problem. It is also preferable to uniformly coat the surface-treated ceramic particles with a low-molecular-weight wax before mixing them with the polymer material. The blending of wax-coated surface-treated ceramic nanoparticles with the polymer material successfully solves the problems caused by non-uniform mixing and dispersion of the ceramic particles and polymer material. Attached Figure Description

[0007] For the purposes of this invention, the accompanying drawings show the currently preferred form; however, it should be understood that the invention is not limited to the precise arrangement and scheme shown.

[0008] Figure 1 This is a schematic diagram of ceramic particles with reactive and non-polar ends coated on their surfaces.

[0009] Figure 2 A schematic diagram depicting ceramic particles with a surface coated with branched hydrocarbon tails surrounding the particle's periphery.

[0010] Figure 3 This is a scanning electron microscope (SEM) image (surface) of a typical (prior art) microporous membrane manufactured by a dry stretching process such as the Celgard dry process.

[0011] Figure 4 This is a SEM image (surface) of a typical (prior art) microporous membrane produced by a wet stretching process.

[0012] Figure 5 This is a SEM image (surface) of a porous membrane produced by a particle stretching method (existing technology).

[0013] Figure 6 It is a SEM image (cross-section) of the edge of a multilayer film, where the upper and lower layers are made of similar or identical polymers, while the middle layer is made of a different polymer (existing technology).

[0014] Figure 7 This is a SEM image of the surface of an embodiment of the membrane of the present invention.

[0015] Figure 8 This is a SEM image of the surface of another embodiment of the membrane of the present invention.

[0016] Figure 9 This is a comparison chart of battery cycle results between the filler membrane of the present invention and conventional microporous membranes. Detailed Implementation

[0017] According to at least some embodiments, the present invention relates to membranes comprising porous membranes or layers made of polymeric materials in which a plurality of surface-treated particles (or surface-treated ceramic particles) with an average particle size of less than about 1 micrometer are dispersed; or to membranes comprising porous membranes or layers made of polymeric materials in which a plurality of particles such as boehmite particles are dispersed; battery separators; related methods of manufacture or use; and so on.

[0018] According to at least selected embodiments, the present invention relates to a membrane comprising a microporous membrane or layer made of a polymeric material wherein a plurality of surface-treated particles (or surface-treated ceramic particles) or waxed surface-treated particles (or surface-treated ceramic particles) with an average particle size of less than about 1 micrometer are dispersed therein, or to a membrane comprising a microporous membrane or layer made of a polymeric material wherein a plurality of boehmite particles are dispersed therein.

[0019] A microporous membrane or layer made of a polymeric material having dispersed a plurality of surface-treated particles (or surface-treated ceramic particles) or wax-coated surface-treated particles (or surface-treated ceramic particles) with an average particle size of less than about 1 micrometer dispersed therein, or a microporous membrane or layer made of a polymeric material having dispersed a plurality of boehmite particles dispersed therein, may be a layer of a multilayer membrane or separator. Preferably, the membrane or layer comprises a microporous membrane made of a polymeric material having dispersed a plurality of boehmite particles with an average particle size of less than about 1 micrometer dispersed therein.

[0020] As used herein, a membrane preferably refers to a solid or continuous polymer sheet or film having a plurality of pores or micropores therethrough. The membrane may also be a nonwoven structure (i.e., made of a plurality of fibers (filaments or staple fibers)); and in some embodiments, the membrane is a layer of a multilayer composite material or product, which may include one or more porous films, one or more nonwoven structures [i.e., made of a plurality of fibers (filaments or staple fibers)], one or more coatings, one or more ceramic coatings, and / or other layers.

[0021] The polymer material can be any polymer material. The polymer material can be a thermoplastic polymer. In one embodiment, the polymer material may be selected from polyolefins, polyamides, polyesters, copolymers thereof, and combinations thereof. In another possibly preferred embodiment, the polyolefin may be selected from polyethylene, polypropylene, polybutene, polymethylpentene, copolymers thereof, and combinations thereof.

[0022] In one embodiment, the polymer material may account for up to about 99.9% by weight of the total weight of the film or layer. In another embodiment, the polymer material may account for 75-97.5% by weight of the total weight of the film or layer. In yet another embodiment, the polymer material may account for 80-95% by weight of the total weight of the film or layer. In still another embodiment, the polymer material may account for 87.5-92.5% by weight of the total weight of the film or layer. In yet another embodiment, the polymer material may account for 90% by weight of the total weight of the film or layer.

[0023] The particles can be loaded into the polymer material at any level. In one embodiment, the particles may constitute about 0.1-30% or about 0.1-10% by weight, or less than about 10% by weight, or 2-10% by weight (or any subset thereof) of the membrane (polymer material and particles) by weight. In yet another embodiment, the particles may constitute 1-10% by weight, or 2-8% by weight, or 3-5% by weight, or 4% by weight (or any subset thereof) of the total weight of the membrane.

[0024] Before loading particles or nanoparticles into polymer materials, or mixing or blending particles or nanoparticles with polymer materials, it is preferable to first treat the surface of the particles or nanoparticles with specially designed molecules to have reactive and nonpolar functional end groups. The reactive ends of the molecules can bind to the surface of the particles or nanoparticles, and the nonpolar ends of the molecules can bind to the polymer material.

[0025] Figure 1Describing exemplary surface-treated particles or nanoparticles, where the "star" symbol represents a reactive functional end group, which in the case of boehmite is a "-OH" group. The nonpolar functional end group located at the other end of the molecule is a hydrocarbon having up to 20 carbon atoms. Furthermore, the hydrocarbon moiety may contain single or double bonds capable of undergoing a reaction to attach one or more additional hydrocarbon functional groups as side chains. These hydrocarbon moieties of the molecule can be long enough that the nonpolar hydrocarbon end groups can surround the exterior of the ceramic particle, effectively increasing the volume occupied by the particle, such as... Figure 2 As described in [the text]. The hydrocarbon tail surrounding the ceramic particles has a surface energy similar to that of the polymer material. In one embodiment, the nonpolar end can be an aliphatic hydrocarbon having <20 carbons and containing double bonds, but any end group capable of miscible (or interacting) with or surrounding the particles can be used. For example, in one embodiment, the aliphatic hydrocarbon may have 20 or fewer carbons (≤20 carbons), in another embodiment it is a hydrocarbon in the range of 5-20, and in another embodiment it is a hydrocarbon in the range of 10-20, and in another embodiment it is a hydrocarbon in the range of 12-18 (and any subset thereof). The nonpolar end can be single-chain or branched. While not wishing to be bound by any particular theory, it is believed that the surface-treated molecules bind to the particles using reactive ends, while the nonpolar ends themselves surround the particles. Now the surface energy of the particles is similar to that of the polymer material, which is beneficial for dispersing the particles into polymer materials with similar surface energies. The coated or treated particles can be further coated (overcoated) with wax or polymer.

[0026] Preferably, the surface coating on the particles alters the surface energy of the particles to be similar to that of the polymer material. Having a similar surface energy allows for better mixing, dispersion, or blending of the nanoparticles with one or more polymer materials.

[0027] In the case of polymer materials used as battery separator membranes, the separator of the present invention has already been prepared using an additional inventive step in the preparation of the ceramic nanoparticles and polymer resin mixture. Because surface-treated ceramic nanoparticles are prone to aggregate and form agglomerates, a second surface treatment is proposed to address this problem. For example, the surface-treated ceramic particles are uniformly coated with a low molecular weight polyolefin (polypropylene or polyethylene) having a molecular weight generally in the range of 800-5,000. The low molecular weight wax has a melting temperature of about 130 to 160 degrees Celsius. When the polymer material is, for example, isotactic polypropylene, the wax can also be isotactic polypropylene. Waxing or treating the surface-treated particles reduces the surface energy of the particles. For example, the surface energy of untreated boehmite particles is 60-80 erg / cm². 2 The order of magnitude of that, while the surface energy of PP is 32 + / - 2 erg / cm. 2Waxing can reduce the surface energy of the particles to roughly correspond to the surface energy of the polymer material, which helps to uniformly mix the particles into the polymer material.

[0028] Liquid wax can be applied and dried to produce wax-coated, surface-treated ceramic particles or nanoparticles. Applying a wax coating is an effective dispersion method for uniformly mixing nanoparticles with polymer materials. Its presence facilitates the uniform dispersion of nanoparticles into the polymer. The mixing of wax-coated, surface-treated ceramic nanoparticles with polymer materials successfully solves the problems caused by non-uniform mixing of ceramic particles and polymer materials. Figure 7 SEM micrographs showing the surface of an example inventive separator membrane containing wax-coated, surface-treated nanoparticles. The particles are mixed so uniformly that they are difficult to see in the sheets and pores of the microporous membrane, but a uniform dispersion can be seen upon close inspection of the micrographs. Figure 8 The image also shows a SEM micrograph of the separator membrane of the present invention, in which the waxed surface-treated particles are very well integrated into the polymer separator membrane. Figure 3 The comparison shows microporous membranes made by a dry process but without any nanoparticles.

[0029] The particles can be loaded into the polymer material at any level. In one embodiment, the particles may constitute about 0.1-30% or about 0.1-10% by weight, or less than about 10% by weight, or 2-10% by weight (or any subset thereof) of the polymer material and the particles. In yet another embodiment, the particles may constitute 1-10% by weight, or 2-8% by weight, or 3-5% by weight, or 4% by weight (or any subset thereof) of the total weight of the membrane.

[0030] The particles can be any type of particle or ceramic particles. In one embodiment, the ceramic particles may be selected from boehmite (AlOOH), SiO2, TiO2, Al2O3, BaSO4, CaCO3, BN, and combinations thereof. In another embodiment, the particles may be boehmite. Boehmite particles are commercially available from Sasol, Johannesburg, South Africa.

[0031] In one embodiment, the particle size ranges from less than 1 micrometer. In other embodiments, the particle size range may be less than about 500 nanometers, less than about 300 nanometers, less than about 200 nanometers, or range from about 20 to about 200 nanometers (and any range included herein).

[0032] While not wishing to be bound by any particular theory, it is believed that the inclusion of nanoparticles can affect the growth of crystalline lamellars in polymer materials. It has been observed that including up to 10% by weight of nanoparticles alters crystal growth, resulting in pores that are typically about 15% smaller than usually observed during pore formation.

[0033] The surface treatment (or coating) molecules can be selected from fatty acids, fatty acid enol esters, fatty alcohols, fatty amines, fatty acid esters, fatty nitriles, and combinations thereof. One such material is available from Lubrizol Corporation in Wycliffe, Ohio.

[0034] Waxes can be any low molecular weight polymer or oligomer. The choice of wax should be compatible with the polymer material (e.g., the wax should be miscible or at least partially miscible with the polymer material). For example, if the polymer material is a polyolefin, the wax can be a similar (but not necessarily identical) polyolefin. Low molecular weight means a molecular weight smaller than that of the polymer material. The molecular weight of a wax can be expressed as molecular weight or viscosity. Molecular weights can be in the range of 800-5000, 1000-5000, or 2000-5000. Viscosity can be less than or equal to 10 centipoise in a temperature range of 150-180°C.

[0035] The premixture of wax and particles can have any mixing ratio. In one embodiment, wax is more abundant than particles. In another embodiment, particles may constitute 30-50% by weight of the premixture, and wax may constitute 50-70% by weight of the premixture. In another embodiment, the particle:wax ratio may be 2:3. In one embodiment, wax may constitute 1.5-15% by weight of the total weight of the film or layer; or 3-12% by weight of the total weight of the film or layer; or 4.5-7.5% by weight of the total weight of the film or layer; or 6% by weight of the total weight of the film or layer (or any subset thereof).

[0036] The aforementioned membrane can be used in any application. In one embodiment, the membrane is a porous or microporous membrane used as a battery separator. The membrane in this application can be one or more layers of a multilayer separator or the only layer of a separator.

[0037] When used as a battery separator (or at least one layer or plate of a separator), the aforementioned membrane can be assembled into any battery. The battery may include a negative electrode, a positive electrode, a separator sandwiched between the negative and positive electrodes, and an electrolyte connected between the negative and positive electrodes. The battery can be a primary or secondary battery. A secondary battery can be a lithium battery or a lead-acid battery.

[0038] The particles can be incorporated into the polymer material in any manner and subsequently formed into a film. In one embodiment, dried, surface-treated ceramic particles are mixed with wax to form a premix; the premix is ​​mixed with a polymer material to form a second mixture; and the second mixture is formed into a microporous membrane. The first (pre)mixing step may include heating, such that the first mixture is a fluid (e.g., a liquid).

[0039] The membrane can be formed in any manner (e.g., by creating micropores). In one embodiment, the membrane can be formed by: extruding the second mixture into a sheet or tube, annealing the sheet or tube, and stretching the annealed sheet or tube. In another embodiment, the membrane can be formed by: extruding the second mixture into a sheet, calendering the sheet, and extracting the pore-forming material from the calendered sheet.

[0040] When the aforementioned membranes are assembled into batteries (e.g., secondary lithium-ion batteries), multiple beneficial effects can be observed. Some examples are: 1) the overall surface energy of the membrane increases significantly, leading to much faster absorption by typical lithium-ion electrolytes; 2) the effective surface friction coefficient tends to decrease because the presence of particles slightly increases surface roughness; and / or 3) the presence of chemically active ceramic particles (e.g., surface-treated boehmite) removes undesirable hydrofluoric acid (HF) from lithium-ion batteries, which in turn contributes to longer cycle life. These three examples of performance changes or improvements can be observed when the nanoparticle loading is less than 10 wt% and perhaps as low as 2 wt%. If the loading is much higher than 10 wt%, the formation of pore structures may become more difficult, and in some cases, it may be impossible to manufacture membranes with porosity >30%. The actual upper limit depends on acceptable separator performance. Furthermore, the presence of nanoparticles is believed to alter the normal crystal growth behavior in the precursor membrane sheet. The particles alter the integrity of crystal growth. The overall conclusion is that adding up to 10% by weight of nanoparticles reduces the crystal size and thus the pore size by about 15% compared to the standard. Example

[0041] The masterbatch is prepared by comprising 40% by weight of surface-treated nanoparticles (surface-treated boehmite with an average diameter of 20-200 nm) and 60% by weight of low molecular weight (800-5000 m.w.) polypropylene wax with a melting temperature of 160 °C.

[0042] The masterbatch is melt-extruded with isotactic polypropylene at 9.5% by weight using a standard ring die (i.e., the standard blown film process well known in the field) to form a 20-micron (thick) precursor.

[0043] The precursor is fabricated into a microporous state using conventional dry stretching methods (see, for example, Kesting, RE). Synthetic Polymer Membranes, A Structural Perspective(2nd edition, Wiley-Interscience, NY, 1985, pp. 290-297, incorporated herein by reference). Tensile conditions included 20% cold stretching (room temperature) and 120% hot stretching (125°C). The resulting films had a thickness of 22.1 μm; Gurley values ​​of 26.1 seconds (ASTM method) and 650 seconds (JIS method); and a porosity of 31.1%. A significant amount of boehmite nanoparticles were well incorporated into the PP resin without any indication of interfacial disruption during stretching. This was due to appropriate particle surface coating and / or treatment. Figure 5 This demonstrates the interfacial failure of existing particles during stretching under large-scale particle stretching conditions.

[0044] The aforementioned membrane (filled with surface-treated nanoparticles) was formed into a conventional coin cell and subjected to 100 cycles. Figure 7 The comparison is shown with similar coin cells, using an unfilled CELGARD 2500 film (Gurley value 200 sec - JIS method). The comparison indicates no significant difference in performance between these specific cells.

[0045] The surface-treated boehmite nanoparticle / polymer blend of the present invention can be used to produce battery separator films that can act as HF scavengers in batteries, effectively extending battery cycle life at a much lower cost than coating battery separator films with an alumina-containing coating. It has been determined that incorporating 10-15% by weight of surface-treated boehmite nanoparticles into the film can also produce excellent HF scavenging effects.

[0046] According to at least selected embodiments, objectives, and aspects of the present invention, a membrane comprises a porous membrane or layer made of a polymeric material wherein a plurality of surface-treated (or coated) particles (or ceramic particles) with an average particle size of less than about 1 micrometer are dispersed therein (other additives, reagents, or materials may be added to the mixture or blend). The polymeric material may be selected from polyolefins, polyamides, polyesters, copolymers thereof, and combinations thereof. The particles may be selected from boehmite (AlOOH), SiO2, TiO2, Al2O3, BaSO4, CaCO3, BN, and combinations thereof, or the particles may be boehmite. The surface treatment (or coating) may be molecules having reactive and non-polar ends. The particles may be premixed in a low molecular weight wax before being mixed with the polymeric material. The membrane may be used as at least one layer of a battery separator.

[0047] Without departing from the spirit and essential attributes of the invention, the invention may be embodied in other forms, and therefore the scope of the invention should be indicated by reference to the appended claims rather than the foregoing description.

Claims

1. A method for manufacturing a membrane, comprising the following steps: Inorganic particles are first surface-treated, then dried, and then mixed with wax to form a first mixture, wherein the wax is a polyolefin wax having a molecular weight in the range of 800-5000; The first mixture is mixed with a polymer material to form a second mixture; and The second mixture is formed into a porous membrane; The average particle size is 20-200 nm; and The membrane contains up to 15% by weight (preferably 10% by weight) of inorganic particles.

2. A membrane comprising: A porous membrane or layer made of a polymer material, wherein a number of inorganic particles are dispersed in the polymer material after surface treatment and then wax coating, the average particle size of the inorganic particles being 20-200 nm. The membrane contains up to 15% by weight (preferably 10% by weight) inorganic particles; and The wax has a molecular weight in the range of 800-5000.

3. A battery comprising: A negative electrode, a positive electrode, a partition sandwiched between the negative electrode and the positive electrode, and an electrolyte flowing between the negative electrode and the positive electrode; The separator comprises a porous membrane or layer made of a polymer material, wherein a plurality of inorganic particles, which have undergone surface treatment and then wax coating, are dispersed in the polymer material, and the average particle size of the inorganic particles undergoing the above dual treatment is 20-200 nm; and The membrane contains up to 15% by weight (preferably 10% by weight) of inorganic particles.

4. A porous membrane filled with nanoparticles, comprising a polymer material wherein ceramic particles with an average particle size of less than about 1 micrometer are dispersed therein, having undergone surface treatment and then surface coating. The surface-coated molecules of nanoparticles have reactive and non-polar ends. The reactive ends are bonded to the surface of the nanoparticles, while the non-polar ends are bonded to the polymer material. Surface coating changes the surface energy of nanoparticles to be similar to that of polymer materials, thereby enabling better mixing or blending of nanoparticles and polymer materials.

5. A method for uniformly mixing and dispersing ceramic particles and polymer resin to prepare a battery separator membrane, wherein, First, the ceramic nanoparticles undergo surface treatment; Before mixing the surface-treated ceramic nanoparticles with the polymer material, a low molecular weight wax is used to uniformly coat the surface-treated ceramic nanoparticles to prevent them from agglomerating and forming aggregates.

6. A method for changing the surface energy of nano-ceramic particles to be similar to that of polymer materials, wherein, First, the nano-ceramic particles undergo surface pretreatment; Then, the nano-ceramic particles are coated with wax. After undergoing a dual surface treatment process involving surface pretreatment and surface waxing, the coated molecules on the surface of the nano-ceramic particles become reactive and non-polar. The reactive ends are bonded to the surface of the nanoparticles, while the non-polar ends are bonded to the polymer material. The nonpolar end is a hydrocarbon with up to 20 carbon atoms, containing single or double bonds that can undergo reactions to add one or more additional hydrocarbon functional groups as side chains; the nonpolar end surrounds the outside of the ceramic nanoparticle, increasing the volume occupied by the ceramic nanoparticle; the hydrocarbon tail surrounding the ceramic nanoparticle has a surface energy similar to that of the polymer material, which facilitates the dispersion of the ceramic nanoparticle into the polymer material.

7. A battery comprising a negative electrode, a positive electrode, a separator sandwiched between the negative electrode and the positive electrode, and an electrolyte flowing between the negative electrode and the positive electrode, wherein, The partition comprises a porous membrane or layer made of a polymer material, wherein a number of particles or nanoparticles are dispersed in the polymer material after surface treatment and wax coating, and the average particle size is 20-200 nm or less than 1 micrometer. The surface of the particles is treated to connect the particles to the membrane; The surface-treated particles are then coated with polyolefin wax; and The particles or nanoparticles can be any particles, ceramic particles or inorganic particles, with ceramic particles selected from boehmite (AlOOH), SiO2, TiO2, Al2O3, BaSO4, CaCO3, BN and combinations thereof.

8. The battery as claimed in claim 7, wherein, The polymer material is selected from: polyolefins, polyamides, polyesters, copolymers thereof, and combinations thereof; The polyolefin is selected from polyethylene, polypropylene, polybutene, polymethylpentene, copolymers thereof, and combinations thereof; Surface-treated and wax-coated particles comprise 2-10% by weight of the porous membrane; and / or The surface treatment utilizes molecules with reactive hydroxyl ends and nonpolar ends.

9. The battery as claimed in claim 7, wherein, The porous membrane is a layer of a multilayer separator; the battery is a lithium battery; the battery is a rechargeable lithium battery; and / or, the battery is a lead-acid battery.

10. The battery as claimed in claim 7, wherein, The porous membrane or layer made of polymer material contains a number of surface-treated particles with an average particle size of less than 1 micrometer dispersed therein; It also includes waxes with a molecular weight of 800-5000 and a melting temperature of 130 to 160°C on the surface-treated particles; The plurality of surface-treated particles comprise 1-10% by weight of the porous membrane. The polymer material further comprises surface-treated or coated ceramic particles selected from SiO2, TiO2, Al2O3, BaSO4, CaCO3, BN, and combinations thereof; and / or The average particle size is less than 500 nanometers.

11. A membrane comprising: A microporous membrane made of a polymer material in which a plurality of surface-treated ceramic particles are dispersed, the surface-treated ceramic particles being nanoparticles, the particles being coated with wax; the particle ends of the coated molecules have reactive "-OH" groups, while the other end of the coated molecules around the particles has nonpolar functional end groups, hydrocarbons having up to 20 carbon atoms.

12. The membrane as described in claim 11, wherein, The polymer material is selected from: polyolefins, polyamides, polyesters, copolymers thereof, and combinations thereof; and / or The plurality of surface-treated ceramic particles constitute 0.1-30% by weight of the film.

13. A battery separator comprising the membrane as described in claim 11 or 12.

14. The battery separator as claimed in claim 13, wherein, The membrane is a layer of a multilayer separator.

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