High-performance battery diaphragm

Abstract

The invention relates to a high performance battery separator. The separator may include a porous support. The separator may include a magnesium fluoride (MgF2) coating on at least a portion of the porous support. A distribution of pore diameters of the separator and a surface energy of the separator may be determined at least in part by the MgF2 coating.

Description

Background Art

[0001] A secondary battery cell may include a separator membrane between the anode of the cell and the cathode of the cell. The separator is used to prevent direct contact between the electrodes of the secondary battery cell to avoid short circuits and potential hazards. Typically, the separator includes a porous electrically insulating material, such as porous polyethylene or porous polypropylene, to allow ions to pass while preventing the flow of electrons between the anode and cathode. This selective permeability helps ions move in the electrolyte of the secondary battery cell, thereby supporting the electrochemical reaction that generates electricity. Summary of the Invention

[0002] In some implementations, a membrane includes a porous support and a magnesium fluoride (MgF2) coating on at least a portion of the porous support, wherein a distribution of pore sizes of the membrane and a surface energy of the membrane are at least partially determined by the MgF2 coating.

[0003] In some implementations, a membrane includes a porous support and a MgF 2 material at least partially coating the porous support, wherein the MgF 2 material partially determines a pore size distribution of the membrane.

[0004] In some implementations, a separator includes a porous support and a MgF 2 material at least partially coating the support membrane, wherein the MgF 2 material at least partially controls a surface energy of the separator. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Figure 1A-1G is a diagram illustrating an example of a high performance separator described herein.

[0006] Figure 2 is a diagram illustrating examples associated with a battery cell including the high performance separator described herein. DETAILED DESCRIPTION

[0007] The following detailed description of example implementations refers to the accompanying drawings, in which the same reference numerals in different drawings may identify the same or similar elements.

[0008] A typical secondary battery cell includes a polyolefin separator. It is worth noting that polyolefins are phase stable up to their melting temperature. For example, the melting temperature range of polyethylene is about 85 degrees Celsius (°C) to about 135°C. This means that typical separators (e.g., separators comprising polyolefins or similar materials) do not provide mechanical stability when the melting temperature of the separator material is exceeded. In addition, conventional separators are not effective mechanical barriers to prevent cell shortening caused by dendrites that may damage the separator. In addition, polyolefins and other similar materials have relatively low surface energy, which limits electrolyte wetting and reduces charge transport of active species (e.g., because the electrolyte cannot properly wet the surface of the separator). Secondary battery cells using standard separator material chemistries exhibit performance limitations that affect the possible use of secondary battery cells in different applications and limit the maximum charging speed.

[0009] Some implementations described herein provide a high-performance separator. In some implementations, the separator includes a porous support and a magnesium fluoride (MgF2) coating disposed on at least a portion of the porous support. Here, the pore size distribution of the separator and the surface energy of the separator are at least partially determined by the MgF2 coating.

[0010] In some implementations, the versatility of the separators described herein is improved (e.g., compared to conventional separators) by enabling the porosity of the separator and / or the surface energy of the separator to be designed (e.g., so that the porosity and / or surface energy can be controlled to achieve a desired goal). In addition, the separators described herein provide improved thermal and mechanical stability. Furthermore, the separators described herein can be used in various battery cell chemistries, such as ternary lithium (Li-NMC), lithium iron phosphate (LFP), lithium sulfur, sodium ion, or other types of battery cell chemistries. In addition, the separators described herein provide improved charge transfer through the separator, thereby improving battery cell performance, reducing charging time, and increasing maximum charge / discharge current. More details are provided below.

[0011] Figure 1A-1G is a diagram illustrating an example of a high performance diaphragm 100 (referred to herein as diaphragm 100). In some implementations, such as Figure 1A-1D As shown, the separator 100 may include a porous support 102 and a MgF 2 coating 106 disposed on at least a portion of the porous support 102 (ie, at least partially coating the porous support).

[0012] exist Figure 1A In the example shown, the porous support 102 includes a support body 103 having a plurality of openings 104 (eg, pores) formed therein, the openings 104 defining the pores of the porous support 102. Figure 1BIn the example shown, the porous carrier 102 includes a carrier body 103 defined by a plurality of carrier elements 104. Here, the carrier elements 104 are connected such that the porous carrier 102 includes openings 105 between the carrier elements 104. Here, the openings 105 define pores of the porous carrier 102. In some implementations, such as Figure 1A and Figure 1B As shown in the illustrated example, the porous support 102 includes a substantially planar surface, and the MgF2 coating 106 is formed on the planar surface of the porous support 102. However, in some implementations, the porous support 102 may include a non-planar surface, and the MgF2 coating 106 may be formed on the non-planar surface of the porous support 102, as shown in FIG. Figure 1C In another example implementation, as shown in Figure 1D As shown, the porous support 102 can be formed from a plurality of support fibers 107 that are connected to form the porous support 102 (e.g., such that openings exist between the support fibers 107 of the porous support 102). In some implementations, the distribution of pore sizes of the membrane 100 and / or the surface energy of the membrane 100 is at least partially determined by the MgF2 coating 106, as described in further detail below.

[0013] It is worth noting that Figure 1A-1D The example of the porous support 102 shown is provided as an example for illustration purposes only. In practice, the porous support 102 may include any type of support having a membrane structure that includes openings, making the porous support 102 porous in nature. In some implementations, the porous support 102 may be formed using various techniques, such as by using fibrous materials, chemical etching, laser cutting, or stamping.

[0014] In some implementations, the porous carrier 102 may include one or more organic materials, such as organic polymers. In some implementations, the porous carrier 102 may include one or more inorganic materials, such as inorganic polymers. In some implementations, the porous carrier 102 may include a combination of organic and inorganic materials (e.g., a combination of one or more organic polymers and one or more inorganic polymers). Non-limiting examples of organic polymers that may be included in the porous carrier 102 include thermoplastics (e.g., polyesters, polyolefins, polycarbonates, polyamides, polyimides, polyimide ethers, polyurethanes, polyanilines, polyarylethers, acrylic acid, acrylates, polyvinyl esters, polyethers, polythiols, silicones, fluorocarbons, copolymers, etc.), thermosetting materials (e.g., epoxy resins, polyurethanes, acrylates, melamine formaldehyde, urea formaldehyde, phenolic resins, etc.) or energy-curable materials (e.g., acrylates, epoxy resins, vinyl, vinyl esters, styrene, silanes, etc.). Non-limiting examples of inorganic polymers that can be included in the porous support 102 include silanes, siloxanes, titanates, zirconates, aluminates, silicates, phosphazenes, polybenzodiazepines, polythiazepines, or glasses (e.g., borosilicate glass, alkali glass, alkali-free glass, metal oxide glass, etc.). In some implementations, the porosity of the porous support 102 alone can be greater than the desired porosity of the membrane 100. Therefore, the formation of the MgF2 coating 106 can be performed to control the porosity of the membrane 100 (e.g., by reducing the porosity compared to the porosity of the porous support 102 alone).

[0015] The MgF2 coating 106 is a coating on the porous support 102. In some implementations, the MgF2 coating 106 at least partially determines the surface energy and / or pore size distribution of the separator 100. That is, the MgF2 coating 106 (e.g., alone or in combination with one or more materials, as described below) can define the surface energy of the separator 100 and / or can define the pore size distribution (e.g., porosity) of the separator 100. In some implementations, applying the MgF2 coating 106 (which is a chemically inert material) to the porous support 102 can improve the performance of the separator 100 by increasing its surface energy. With respect to battery cell chemistries, the lower the surface energy of the separator, the higher the repellency properties of the separator surface. Therefore, the lower the surface energy, the slower the filling of the battery cell with electrolyte. Compared to materials used in conventional separators, MgF2 inherently has a higher surface energy than polyolefin materials, which means that the wettability of the separator 100 including the MgF2 coating 106 is improved and the electrolyte filling time during battery cell assembly is shortened. In addition, the MgF2 coating 106 improves charge transfer during charging of the battery cell including the separator 100, while also improving the battery discharge performance. In addition, the use of MgF2 enables control over the scaling of the porosity of the separator 100. Conventional separators have a fixed porosity distribution and material properties, which pose challenges in wettability and controlling porosity. This is important because in operation, charge carriers are allowed to move back and forth between the anode and cathode, while the rest of the battery chemistry should be separated. MgF2 provides control over porosity at different levels. Therefore, the MgF2 coating 106 can be formed to control the surface energy of the separator 100 and the porosity of the separator 100. Generally, higher surface energies are conducive to electrolyte chemical charge interactions and provide improved pore distribution. Therefore, the MgF2 coating 106 can enable the separator 100 to be used in battery chemistries with relatively small species that need to be separated, such as battery chemistries including lithium sulfate (Li2S4), thereby improving the selectivity of the separator.

[0016] In some implementations, the diaphragm 100 may include one or more other materials, such as magnesium oxide (MgO), magnesium oxyfluoride (MgO), or magnesium oxide (MgO) disposed on or within at least a portion of the MgF2 coating 106. x F y O z, where 1≤x≤4, 1≤y≤5, 1≤z≤4) or aluminum oxide (Al2O3). In some implementations, these one or more other materials can be used to further determine or define the surface energy of the separator 100 (e.g., by increasing the surface energy compared to the MgF2 coating 106 alone) and / or further determine or define the pore size distribution of the separator 100. More generally, these one or more other materials can be used to improve or increase control over the matching of the wetting characteristics or surface energy of the separator 100 (as defined by the chemical composition of the surface of the separator 100) with the characteristics of the electrolyte, while also providing a desired pore size distribution of the separator 100. In some implementations, these one or more other materials can increase the range of achievable surface energies of the separator 100 (e.g., compared to MgF2 alone).

[0017] For example, in some implementations, the membrane 100 can include a MgO material 108 on or within at least a portion of the MgF 2 coating 106 . Figure 1E is a diagram illustrating an example of a separator 100 including an MgO material 108. In some implementations, the formation of the MgO material 108 can be adjustable (e.g., during the manufacturing process of the separator 100) to provide further control over (e.g., further increase) the surface energy of the separator 100, thereby enabling further improvement in the electrolyte wettability of the separator 100. Thus, the MgO material 108 can be used to enable faster filling with electrolyte after a battery cell including the separator 100 is assembled, and provide improved charge transfer for the battery cell including the separator 100.

[0018] As another example, in some implementations, the diaphragm 100 can include an Al 2 O 3 material 110 on at least a portion of the MgF 2 coating 106 . Figure 1F is a diagram illustrating an example of a separator 100 including an Al2O3 material 110. In some implementations, the Al2O3 material 110 enables further control of the surface energy of the separator 100 (e.g., further increase compared to MgF2 alone). In some implementations, terminating the MgF2 coating 106 with a separate layer material (such as the Al2O3 material 110) can enable control of the surface energy of the separator 100 or the wetting characteristics of the separator 100 (e.g., for a given battery cell electrolyte and battery cell architecture).

[0019] As another example, in some implementations, the diaphragm 100 may include MgF2 on or within at least a portion of the MgF2 coating 106. x F y O z Materials. In some implementations, Mg x F y O zThe material may further enable control or improvement of one or more properties of the separator 100 (eg, surface energy or electrolyte wettability). x F y O z The material may include any material on the continuum between pure MgF2 and pure MgO. In some implementations, the transition between the MgF2 coating 106 and the MgO material 108 may include various Mg x F y O z The materials, the formation of which can be designed to provide a controlled or desired surface energy and / or pore size distribution to the membrane 100 .

[0020] In some implementations, one or more materials of the membrane 100 may at least partially determine the distribution of pore sizes of the membrane 100 and / or the surface energy of the membrane 100. For example, the MgF2 coating 106 and one or more other materials (e.g., MgO material 108, Al2O3 material 110, and / or Mg x F y O z The surface energy of the separator 100 may be designed to be in the range of about 35 millinewtons per meter (mN / m) to about 1000 mN / m. It is worth noting that different battery cell concepts may require different surface energies of the separator 100 to obtain optimal performance, and the surface energy of the separator 100 may be designed for a given battery cell concept or application (e.g., through controlled formation of the MgF2 coating 106 and one or more other materials). In some embodiments, the distribution of pore sizes includes pore sizes in the range of about 2 nanometers (nm) to about 1000 nm. It is worth noting that different battery cell concepts may require different pore size distributions of the separator 100 to obtain optimal performance, and the pore size distribution of the separator 100 may be designed for a given battery cell concept or application (e.g., through controlled formation of the MgF2 coating 106 and one or more other materials).

[0021] In some implementations, by adjusting or otherwise controlling one or more materials of the diaphragm 100 (e.g., the MgF2 coating 106, the MgO material 108, the Al2O3 material 110, and / or the Mg x F y O zThe process technology and / or process conditions (e.g., pressure, deposition rate, etc.) for the deposition of the one or more materials can be used to design the microstructure of the one or more materials and thereby design the pore size and pore size distribution of the separator 100 (e.g., to meet the performance requirements of the battery cell in a given application). In some implementations, process gases associated with the formation of the one or more materials (such as nitrogen (N2), argon (Ar), or oxygen (O2)) can be used in various mixing ratios in association with the control of the formation of the one or more materials. In some implementations, a given one of the one or more materials of the separator 100 can be formed using vacuum deposition, wet chemical deposition, or another type of process. In some implementations, the vacuum process associated with the formation of the MgF2 coating 106 and / or one or more other materials of the separator 100 can be used at approximately 10 -6 The membrane 100 is performed at pressures ranging from 100 torr to about 100 mtorr. It is worth noting that the substrate temperature or the technique used to activate the surface may affect the layer growth, directionality, or microstructure of the MgF2 coating 106 or one or more other materials. In some implementations, an engineered balance of amorphous and crystalline phases controls the microstructure and pore distribution of the membrane 100.

[0022] In some implementations, one or more properties of the membrane 100 can be designed using material stoichiometry, including doping of the MgF2 coating 106 and / or one or more other materials of the membrane 100. In some implementations, the stoichiometry of the MgF2 coating 106 and / or one or more other materials of the membrane 100 can be designed by co-deposition and / or coating chamber conditions: the water vapor and oxygen content during the deposition process changes the stoichiometry of the MgO and MgF2, and ... x F y O z In some implementations, as described above, the MgO phase can improve the wetting behavior of MgF2 by increasing the surface energy of the separator 100. This will also increase the charge transfer rate through the separator 100.

[0023] In some implementations, a vapor phase chemical deposition process can be utilized that uses vaporized precursor materials that react in the vapor phase or on the surface of the porous support 102 to form a porous layer of MgF2 to form the MgF2 coating 106. The chemical deposition process can be performed in, for example, about 10 -6 The pressure range is from torr to about 1000 mtorr. The stoichiometry of the MgF2 coating 106 and the additional materials (such as MgO, Mg x F y O zThe ratio of MgF2 coating 106 to Al2O3 or other oxides for tailoring surface energy properties can be adjusted by using additional precursors and process gases. Adding plasma during processing allows the microstructure of the MgF2 coating 106 to be tailored to adjust the porosity and / or surface energy of the membrane 100. Figure 1G 1 is a diagram illustrating an example of a diaphragm 100 formed using a vapor phase chemical deposition process. Figure 1G As shown, the use of a vapor phase chemical deposition process causes the MgF2 coating 106 to follow the surface of the porous support 102 and fill the pores as desired.

[0024] In some implementations, a vapor phase chemical deposition process may be performed using an evaporated precursor that adsorbs on the surface of the porous substrate and fills the pores of the porous support 102 , and then forms a MgF 2 layer on the surface of the porous support 102 .

[0025] In some implementations, a layer can be formed on the porous substrate using a liquid coating process, which can form a colloidal particle and / or polymer network. In some implementations, the layer can be cross-linked via light, heat, or a chemical reaction to form a MgF2 porous layer on the porous support 102.

[0026] In this way, the porosity of the separator 100 can be engineered, which means that the versatility of the separator 100 is improved (e.g., allowing the separator 100 to be used in a variety of battery cell chemistries and applications). In addition, the surface energy of the separator 100 can be engineered, which means that the performance of a battery cell including the separator 100 and / or the performance of an assembly of a battery cell including the separator 100 can be improved.

[0027] In addition, in some implementations, the thickness of the separator 100 can be reduced (e.g., compared to a conventional separator comprising a stack that includes two or more layers of material to achieve a desired porosity distribution). In addition, the separator 100 described herein provides chemical stability with respect to battery cell chemistries (e.g., different components and electrolytes) while also providing mechanical stability with respect to stretching and cell deformation. In addition, the separator 100 provides mechanical and chemical stability against dendrite penetration. In addition, the separator 100 can have improved thermal stability, which means that the likelihood of melting is reduced and, in addition, enables an increase in the thermal operating range (e.g., increasing the thickness of the MgF2 coating 106 and / or one or more other materials can improve thermal performance). In addition, the separator 100 described herein reduces the electrolyte fill time during battery cell assembly (e.g., compared to a battery cell comprising a conventional separator). In some implementations, the separator 100 described herein provides improved performance for various battery cell chemistries, including but not limited to solid-state lithium battery cells, lithium-sulfur battery cells, sodium-ion battery cells, or other types of battery cell chemistries.

[0028] As mentioned above, Figure 1A-1G are provided as examples. Other examples may be related to Figure 1A-1G Different from what is described in .

[0029] Figure 2 is a diagram illustrating an example associated with a battery cell 200 including the high performance separator 100 described herein. Figure 2 As shown, battery cell 200 includes an anode 202 (eg, a lithium (Li) anode), a cathode 204 (eg, a sulfur (S) cathode), and separator 100 including (at least) a MgF 2 coating 106 .

[0030] exist Figure 2 In the example shown, the improved porosity distribution provided by the separator 100 prevents lithium polysulfides (Li x S y , x>2, y>2) from the cathode side of the battery cell 200 to the anode side of the battery cell 200, which would otherwise degrade the performance of the battery cell 200 over time. Figure 2 As shown, lithium ions (Li+) required for charge transfer can pass through the separator 100. Notably, conventional polyolefin separators do not prevent the shuttling of polysulfides, which means that the separator 100 provides improved performance (e.g., compared to Li-S batteries including conventional polyolefin separators).

[0031] As mentioned above, Figure 2 is provided as an example. Other examples can be found in relation to Figure 2 Different from what is described.

[0032] The above disclosure provides illustration and description, but is not intended to be exhaustive or to limit the implementation to the precise form disclosed. Modifications and variations are possible in light of the above disclosure or may be acquired from practice of the implementation.

[0033] Although specific combinations of features are cited in the claims and / or disclosed in the specification, these combinations are not intended to limit the disclosure of various implementations. In fact, many of these features can be combined in a manner that is not specifically cited in the claims and / or not disclosed in the specification. Although each dependent claim listed below can only directly depend on one claim, the disclosure of various implementations includes the combination of each dependent claim with each other claim in the claim set. As used herein, the phrase "at least one" in a list of reference items refers to any combination of these items, including single members. For example, "at least one of a, b, or c" is intended to cover a, b, c, ab, ac, bc, and abc, as well as the combination of multiple items in the same item.

[0034] Unless explicitly stated, any element, behavior or instruction used in this article should not be interpreted as key or essential. In addition, as used in this article, the article "one" and "an" are intended to include one or more projects and can be used interchangeably with "one or more". In addition, as used in this article, the article "said" is intended to include one or more projects quoted in combination with the article "said", and can be used interchangeably with "one or more". In addition, as used in this article, the word "set" is intended to include one or more projects (for example, related projects, unrelated projects, or a combination of related and unrelated projects), and can be used interchangeably with "one or more". If only one project is intended to be used, phrase "only one" or similar language is used. In addition, as used in this article, the term "having", "having", "containing" etc. are intended to be open terms. In addition, unless explicitly stated otherwise, the word "based on" is intended to represent "at least partially based on". In addition, as used in this article, the term "or" is inclusive when used in series, and can be used interchangeably with "and / or", unless explicitly stated otherwise (for example, if used in combination with "any one" or "only one in ... ").

Claims

1. A diaphragm comprising: porous support, and a magnesium fluoride MgF2 coating located on at least a portion of the porous support, The distribution of the pore sizes of the membrane and the surface energy of the membrane are at least partially determined by the MgF2 coating.

2. The diaphragm of claim 1, further comprising an aluminum oxide (Al2O3) material on at least a portion of the MgF2 coating.

3. The membrane of claim 1 , further comprising a magnesium oxide (MgO) material on or within at least a portion of the MgF 2 coating.

4. The membrane of claim 1 , further comprising magnesium oxyfluoride (Mg 2 O) on or within at least a portion of the MgF 2 coating. x F y O z , where 1≤x≤4, 1≤y≤5, 1≤z≤4) material. The membrane of claim 1 , wherein the porous support comprises at least one of an organic material or an inorganic material. The membrane of claim 1 , wherein the surface energy of the membrane is in a range from about 35 millinewtons per meter (mN / m) to about 1000 mN / m. The membrane of claim 1 , wherein the distribution of the pore sizes comprises pore sizes within a range from about 2 nanometers (nm) to about 1000 nm.

8. A diaphragm comprising: porous support, and A magnesium fluoride MgF2 material at least partially coats the porous support, wherein the MgF2 material partially determines the pore size distribution of the separator. 9 . The membrane of claim 8 , wherein the pore size distribution of the membrane comprises pore sizes in a range from about 2 nanometers (nm) to about 1000 nm.

10. The membrane of claim 8, wherein the MgF2 material at least partially controls the surface energy of the membrane. The membrane according to claim 10 , wherein the surface energy of the membrane is in the range of about 35 millinewtons per meter (mN / m) to about 1000 mN / m.

12. The membrane of claim 8, further comprising an aluminum oxide (Al2O3) material on at least a portion of the MgF2 coating.

13. The membrane of claim 8, further comprising a magnesium oxide (MgO) material on or within at least a portion of the MgF2 coating.

14. The membrane of claim 8, further comprising magnesium oxyfluoride (Mg x F y O z , where 1≤x≤4, 1≤y≤5, 1≤z≤4) material.

15. The membrane of claim 8, wherein the porous support comprises an organic polymer, an inorganic polymer, or a combination of an organic polymer and an inorganic polymer.

16. A diaphragm comprising: porous support, and A magnesium fluoride MgF2 material at least partially coats the porous support, wherein the MgF2 material at least partially controls the surface energy of the separator.

17. The membrane of claim 16, wherein the MgF2 material partially determines the pore size distribution of the membrane.

18. The membrane of claim 16, further comprising an aluminum oxide (Al2O3) material on at least a portion of the MgF2 coating.

19. The membrane of claim 16, further comprising a magnesium oxide (MgO) material on or within at least a portion of the MgF2 coating.

20. The membrane of claim 16, further comprising magnesium oxyfluoride (Mg x F y O z , where 1≤x≤4, 1≤y≤51≤z≤4) material.

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