Base-treated battery separator exhibiting hydrofluoric acid scavenging properties

Abstract

This invention provides a base-treated battery separator that exhibits hydrofluoric acid scavenging properties. [Solution] This disclosure relates to a separator for lithium-ion batteries that exhibits hydrofluoric acid scavenging properties after treatment with a certain type and amount of caustic compound. Such basic treatment reacts with HF to form a surface complex with a counterion that scavenges dissociated fluoride ions, thereby reducing the amount of potentially damaging acid within the battery during its use. Such surface counterion-fluorine complexes on the separator have a low tendency to subsequently dissociate and therefore reduce the presence of oxidizing / acidic fluoride ions, extending the lifespan of the battery cells through increased charge levels.

Description

[Technical Field]

[0001] (Cross-reference of related applications) This application claims priority to the pending U.S. Provisional Patent Application No. 63 / 170,435, filed on 2 April 2021, which is incorporated herein by reference in its entirety.

[0002] This disclosure relates to a separator for lithium-ion batteries that exhibits hydrofluoric acid scavenging properties after treatment with a certain type and amount of caustic compound. Such basic treatment reacts with HF to form a surface complex with a counterion that scavenges dissociated fluoride ions, thereby reducing the amount of potentially damaging acid within the battery during its use. Such surface counterion-fluorine complexes on the separator have a low tendency to subsequently dissociate and therefore reduce the presence of oxidizing / acidic fluoride ions, extending the lifespan of the battery cells through increased charge levels. [Background technology]

[0003] The main obstacle to the cost-effective adoption of advanced lithium-ion batteries (LIBs) is the problem of capacity degradation / reduced cycle life. Conventional lithium-ion battery electrolytes typically consist of a mixture of linear and cyclic organic carbonates and lithium hexafluoride phosphate (LiPF6). Even the highest purity grades of battery electrolytes typically contain about 25 ppm of water, which may be due to the hygroscopic properties of LiPF6, without being limited by mechanism. The presence of water and moisture causes the decomposition and subsequent formation of HF, which attacks and dissolves transition metals in many different cathode compositions. The presence of hydrofluoric acid (HF) in the liquid electrolyte has been identified as a major cause of this decomposition and reduced battery life. The dissolved metal ions migrate to the lithium / graphite anode, causing plating and failure of the lithium / graphite anode. HF can also attack and leach out non-metallic compounds (e.g., LiF) deposited on the cathode surface. When this occurs, the cathode surface on which LiF had previously been deposited is exposed to the electrolyte solution, and further electrolyte decomposition occurs on the newly exposed surface. To improve the structural stability of the cathode in the presence of HF, several approaches have been used, including protective coatings and the use of basic additives in the electrolyte to chemically capture HF. Protective / reactive coatings have also been deposited on the separator. One drawback of all these approaches is that they increase the mass and volume of the LIB without contributing to the capacity and / or power density of the LIB. Furthermore, battery decomposition cannot be easily detected before the point of battery failure occurs. Therefore, the ability to reliably capture fluoride ions within the lithium-ion battery cell of interest (liquid electrolyte type) is highly beneficial in this field. [Overview of the project] [Problems that the invention aims to solve]

[0004] An obvious advantage of this disclosure is its ability to reduce harmful free HF in a battery through the provision of appropriately treated separator components. Another obvious advantage is that the process of caustically treating pre-formed separators introduced into a battery device for such HF reduction becomes easier. Thus, another obvious advantage of this disclosure is its ability to provide improvements to a typical rechargeable battery having such treated separators. [Means for solving the problem]

[0005] Accordingly, the present disclosure relates to a battery separator for lithium-ion battery cells, wherein the battery separator exhibits counterions on its surface, and the counterions have a maximum pK of 6.0, preferably a maximum pK of 4.0. b The disclosure includes a battery separator for lithium-ion battery cells, characterized in that the battery separator exhibits hydrofluoric acid scavenging properties, and is selected from a group of ions conferred by a base having a level. Furthermore, the disclosure includes the battery separator wherein the counterion is selected from sodium ions, magnesium ions, potassium ions, barium ions, and calcium ions. The disclosure also includes batteries (and other energy storage devices) comprising the battery separator.

[0006] As previously mentioned, hydrogen fluoride, HF, and aqueous solutions of hydrogen fluoride (hydrofluoric acid) are highly corrosive compounds. HF corrosion is a problem particularly relevant to batteries containing lithium, lithium hexafluoride phosphate, or other lithium salts containing fluorine. This application addresses pK levels up to 6.0 (preferably up to 4.0 as described above). bThe present invention provides one or more separators that capture HFs, indicating the presence of counterions of bases. The term “HF-capturing separator” is intended to refer to a separator that captures, binds, traps, restrains, reacts with, fixes, or retains HFs. HFs in an HF-capturing separator are less likely to damage components compared to free HFs. In some embodiments, HF-capturing separators increase battery life. Such separators also exhibit hygroscopic properties, as described above, allowing for moisture absorption within the battery cell in question during use.

[0007] A lithium-ion battery is provided that features a pre-formed and subsequently caustically treated battery separator and exhibits increased HF capture (and potential moisture absorption) characteristics. The provided battery may exhibit reduced HF damage. The term “reduced HF damage” is intended to mean a reduction, mitigation, and / or improvement of HF-related damage to one or more battery components compared to a battery without such a particularly caustically treated pre-formed separator, relating to reduced or mitigated HF-related damage over a period of time or over a long period of time, with medium to high capacities. A lithium-ion battery having increased HF capture characteristics features components arranged with or covered by such pre-formed caustically treated separators. The arranged / covered components may be selected from a group of components including an anode, cathode, encapsulation material (and possibly a current collector as well) and different types of electrolyte ion-conducting materials. The term “encapsulation material” is intended to mean any structure or device surrounding the anode, cathode and electrolyte, such as walls, lids, caps, floors, cans or canisters, but is not limited to these. Therefore, a base-treated separator article may be introduced by a lithium structure manufacturing procedure that includes placing such treated separator between the anode and cathode, including at least one current collector (with connections to allow the transfer of electricity from the battery to the outside), placing the resulting structure in a cell housing, introducing a liquid electrolyte therein, and sealing the liquid electrolyte. The resulting lithium-ion battery can then be charged and recharged and used together with external mechanical / electrical devices to supply power to those devices.

[0008] low pK bThe HF-capturing ability of pre-formed separator articles treated with a compound, and the presence of certain counterions on their surface, yields extremely effective results in reducing degradation and damage to internal battery cells in use while simultaneously improving cell charge life and its cycle. Therefore, this disclosure provides, as one hypothetical embodiment, a hydrogen fluoride (HF)-capturing separator article (nonwoven fabric or film), and, more specifically, a hypothetical hygroscopic separator in which, in addition to HF, the membrane can also absorb moisture within the battery cell in question. Such hypothetical separators can first be formed or manufactured and then subjected to a basic treatment to induce complex formation of hydroxyls present on the surface with counterions from the surface. In various embodiments, such a basic includes, but is not limited to, sodium hydroxide, potassium hydroxide, lithium hydroxide, barium hydroxide, calcium hydroxide, and magnesium hydroxide, with a pK of up to 6.0 (preferably up to 4.0). b A base is selected from a group of bases exhibiting the following properties. Such a moisture-absorbing film may further contain at least one additive, such as Al2O3, but is not limited to these. Such a separator that provides sufficient physical properties for the battery (or other similar energy storage device) in question preferably exhibits a tensile strength of at least 35 MPa and an air permeability of more than 65 Gurley. Furthermore, such possible embodiments of the separator exhibit high ionic conductivity and d dendr The following average pore sizes are shown.

[0009] This disclosure further provides a battery (or other type of energy storage device, such as a capacitor) having enhanced moisture-capturing properties. This battery comprises a hygroscopic separator on which surface complexed counterions are present after caustic treatment. Thus, the disclosed battery exhibits a reduced HF damage tendency in association with such a treated separator. One (or more) such separators are introduced between the anode and cathode and adjacent to at least one current collector in such a battery (or energy storage device) of interest. An embodiment of such a battery exhibits at least 90% capacity after 250 cycles.

[0010] Accordingly, the present disclosure provides a method for reducing moisture in a battery, which includes incorporating the moisture-absorbing membrane of the present application into the battery, and which may simultaneously involve reducing free HF in the battery.

[0011] Unless otherwise defined, all technical and scientific terms used herein have the meanings generally understood by those skilled in the art.

[0012] As used herein, "A," "an," and "the" may refer to more than one referent, unless they are explicitly and unintentionally limited to a single referent.

[0013] The term "separator" is intended to include films, nonwoven structures, sheets, laminates, textiles, or planar flexible solids. Separator properties include, but are not limited to, thickness, strength, flexibility, tensile strength, porosity, and other properties. It is recognized that different separators or different types of separators may exhibit different or similar properties.

[0014] The term "ion-conducting separator" refers to a separator between two electrodes, which are either anode and cathode, or positive and negative electrodes. An ion-conducting separator divides, separates, or partitions two regions while allowing the flow of ions between them.

[0015] The term “hygroscopic separator” is intended to include separators that absorb, take in, retain, immerse, internalize, or capture liquids. Liquids of interest include, but are not limited to, organic solutions, aqueous solutions, electrolyte solutions, hydrofluoric acid, HF, and carbonate-based electrolyte solutions. Preferably, such caustrated HF capture (and moisture absorption by hygroscopic groups that may be present on the surface) generally retain their original size when absorbing moisture, or generally change their size minimally, and most reliably completely cover the separation interface between electrodes.

[0016] Appropriate low pK as described herein bThe types of one or more separators (two or more may be used in a battery) that are treated with a base include: i) films, for example, polyolefins such as polypropylene, polyethylene, double-layered polypropylene and polyethylene, and combinations of these polyolefin films, such polyolefins having a ceramic coating (which may contribute to an increased ability to form complexes with the base pair ions themselves); ii) ceramic separators, either alone or with nonwoven reinforcement; iii) nonwoven fabric structures having a ceramic coating; iv) nonwoven fabric structures having microfibers, nanofibers, or combinations thereof, uniformly sized microfibers, etc. This may include, but is not limited to, nanofibers of one size, enmeshed microfibers and nanofibers, single-layer nonwovens of such kinds, individual microfiber layers, individual nanofiber layers, double or multilayer nonwovens of individual layers of enmeshed and / or combined microfibers and nanofibers, and any combination thereof, as well as polymer structures having independent surface groups and parts that can form complexes with base counterions, including but not limited to, polyvinyl alcohol films, polycarbonate films (both having free hydroxyl groups present on their surface, as a non-limiting example), combinations thereof, etc. The ability to harmonize such basic treatment with fluorine-capturing counterions present on the separator surface provides the desired effect, and therefore any kind of separator having such treated and / or free complexing groups thereon, and not limited in terms of the possibility of such complex formation (again, hydroxyl groups, as a non-limiting example), can thus be used and implemented. Since the electrolyte flows through such a separator in such a battery, and the generation of HF within the target cell, and therefore the presence of HF, has been proven to be highly likely to be corrected with difficulty, the permissible and well-understood purpose of the separator in lithium-ion battery structures is to serve this overall capability.As mentioned above, hydrogen fluoride (and therefore ultimately hydrofluoric acid) is considered to be a reaction product resulting from the interaction between the electrolyte and water in lithium-ion batteries. Such oxidizing ionic compounds (essentially free fluoride ions) can bind internally to delicate metal components, thereby reducing their effectiveness and potentially leading to cell failure. Thus, such acidic species are considered to contribute to the degradation of the battery cells in question over time. Furthermore, this process can be slow and constant for extended periods, resulting in degradation related to battery charging (especially in such rechargeable lithium-ion types), leading to significantly shorter charge cycles and requiring users to charge more frequently. Ultimately, the charge cycles will maintain lower charge levels, leading to the invalidation and replacement of the battery cells. Moreover, such cell degradation can also cause the electrolyte to form undesirable and potentially dangerous dendritic crystals and similar structures within the cell, which can at least cause short circuits. Therefore, the ability to mitigate the likelihood of such destructive consequences can be crucial for such lithium-ion battery technologies.

[0017] Such base-treated separators can be of any kind that provide the required electrolyte transfer within the target cell between electrodes (for example, through the presence of pores of a size suitable for such purposes), as described above. Such separators can be formed from different materials, including, in one non-limiting example, nonwoven structures formed from various types of fibers (as described above). Such fibers can be of any diameter, from fibers of uniform size and structures having the same fiber constituent material to fibers of various sizes formed from different materials. Thus, materials can be selected from synthetic and natural fibers with diameters of microns and nanometers, combinations of microfibers and nanofibers, entangled microfibers and nanofibers, and so on. Such fibers may be essentially polymers in terms of material, and include, but are not limited to, cellulose, polyacrylonitrile, polyolefins, polyolefin copolymers, polyamides, polyvinyl alcohol, polyethylene terephthalate, polybutylene terephthalate, polysulfone, polyvinyl fluoride, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polymethylpentene, polyphenylene sulfide, polyacetyl, polyurethane, aromatic polyamides, semi-aromatic polyamides, polypropylene terephthalate, polymethyl methacrylate, polystyrene, synthetic cellulosic polymers, and admixtures, mixtures, and copolymers thereof. Such fibers may be provided as microfibers and nanofibers to form single-layer structures (nonwovens) in which the required aramid fibers are also present. Such structures may be formed, for example, according to the materials and methods disclosed in U.S. Patents No. 8,936,878, No. 9,637,861, and No. 9,666,848.

[0018] Such separators may also be film structures, as described above. Such films include those having a porous structure for effective electrolyte transfer (as also described above). Examples include, but are not limited to, CELGARD and POLYPORE separator products (polyolefin types such as polypropylene films having electrolyte transfer capabilities, as also described above). Other possible separator articles provided as manufactured structures for subsequent base treatment include, but are not limited to, ceramic separators, nonwoven fabric types with ceramic coatings, polyolefin film types with ceramic coatings, polycarbonate films, polyvinyl alcohol films, and combinations thereof, as previously stated.

[0019] After providing such a separator structure for final implementation and introduction into the target lithium-ion battery cell, the separator is treated with a base to bring about the presence of complexed counterions (sodium ions, magnesium ions, calcium ions, potassium ions, barium ions, lithium ions, etc., although this is possible if lithium hydroxide is used as the caustic base, and to a lesser extent) on the separator surface. The ability to form such complexes can be increased by the presence of certain materials having free hydroxyl (or similar) groups as separator components. A base application pretreatment may also be performed, at least hypothetically, to enable such complex formation to occur. Thus, such caustic treatment may include, but is not limited to, any application steps such as dipping, spraying, spray coating, brush (or similar) coating and any similar procedures. Such a basic formulation may be of any appropriate molar concentration to ensure that complex formation occurs on the separator surface in question, at a level that does not prove to be harmful in itself to the separator article, which may be thin and delicate, during use. Therefore, the concentration of the base in such a treatment formulation may be about 0.1 to 10 molar concentrations (in aqueous solution, or in an aprotic solvent such as DMSO, for example, but not limited to possible ones). More noteworthy with respect to molar concentration is the possible level of 0.2 to 5, most preferably 0.5 to 5. Similarly, such levels allow for sufficient counterion loading when applied to the target separator surface; if the molar concentration is too low, it will not be able to generate the level necessary for fluoride ion capture (capture), and if it is too high, it may cause undesirable degradation of the target separator article itself. Therefore, the introduced base treatment should result in such desired complex levels without actually damaging or shrinking the separator in question. Accordingly, the method may further include a drying step to remove excess moisture (due to the aqueous properties of the caustic formulation) from the separator surface before subsequently introducing it into the target lithium-ion battery cell.Such a drying step may particularly include the possibility of oven drying, vacuum drying, air drying, or forced air drying at a sufficiently low temperature level sufficient to ensure dimensional stability of the treated separator article prior to such battery cell assembly.

[0020] The bases (as described above) used in the caustic treatment after separator formation / manufacture include, but are not limited to, sodium hydroxide, potassium hydroxide (KOH), lithium hydroxide, calcium hydroxide, barium hydroxide and magnesium hydroxide, all of which have a pK b of at most 6.0, more specifically at most 4.0. In some methods, the preferred base is sodium hydroxide (NaOH) or KOH. In other methods, the preferred base is calcium hydroxide or barium hydroxide. The ability to form surface counterion complexes on a target separator by such subsequent caustic treatment procedures (after manufacture and / or formation as described herein) provides the separator thus treated with a distinct HF scavenging capability, and optionally moisture absorption properties in some cases. Accordingly, any base having a pK of at most 6.0, preferably at most 4.0 b whose separator exhibits the counterion of any such base on its surface is included within the present disclosure.

[0021] Counterion complexation on the surface of the target separator can be carried out in an amount sufficient to achieve such a desired fluorine scavenging level (and potentially also enable moisture absorption). Such counterion levels can be measured using an X-ray photoelectron spectroscopy (XPS) procedure after the above complex formation and drying steps. A counterion percentage standard of 0.01 to 1 (preferably 0.1 to 1, more preferably about 0.1 to about 0.75) based on the total weight of the separator can be targeted for this purpose. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] [Figure 1] Figure 1 is a graph showing the pH of tested treated and untreated separators versus surface area. [Figure 2] Figure 2 shows a graph of the HF concentration on the tested separator against its surface area. [Figure 3] Figure 3 shows a graph of the difference in HF concentration on the tested separator against surface area. [Figure 4] Figure 4 shows a graph of the moles of captured HF on the separator tested against surface area. [Figure 5] Figure 5 shows a graph of grams of captured HF on the tested separator against grams of the separator. [Modes for carrying out the invention]

[0023] The following descriptions and examples represent only possible embodiments of this disclosure. With regard to the claims, the scope and breadth of such disclosure will be readily apparent to those skilled in the art.

[0024] As mentioned above, the discovery that caustic-treated battery separators (lithium ion, sodium ion, etc.) for rechargeable systems provide hydrofluoric acid (or hydrogen fluoride) capture brings improvements in this field that enable overall safety and performance enhancements. In this regard, we provide separators, treat them with certain caustic solutions, and then individually test the separators for several properties related to such HF concentration and pH levels.

[0025] To this end, we conducted studies to evaluate the HF capture performance of a representative battery separator type (Dreamweaver Gold 20) and the performance of the same separator after base treatment.

[0026] (Preparation of Separators) Various amounts of dried separators were exposed to a fixed amount of dummy electrolyte (an electrolyte component that does not contain cyclically reacting LiPF6 salts). The dummy electrolyte contained the original HF content to test HF capture exclusively with respect to caustic treatment. Some separator samples were pre-treated with an excess of base solution and appropriate wastewater, and then thoroughly dried to remove residual base solution, while other samples were left untreated. For comparison, separators (described later) were treated with 3N sodium hydroxide and 3N barium hydroxide, while other samples were left untreated with respect to the basic solution. The resulting solutions were measured for pH levels, which allowed for studies on the amount of separator and base treatment regarding the effect of separator HF capture ability.

[0027] Using an A4 hand sheet of Dreamweaver Gold 20 separators, discs were cut from such hand sheets using a 13mm diameter die or Silhouette Cameo4 cutter. In the case of Cameo4, the A4 sheet was taped to a low-tack backing material and fed into the instrument. A manual blade was used with its depth set to 7. The Cameo4 program settings included 2 depth settings, 15 force settings, and 10 passes. The Cameo4 software was programmed with an array of 13mm discs. After cutting / punching, the discs were placed in small 20mL PTFE vials. Such PTFE vials were used to avoid corrosion in conventional glass vials associated with the presence of HF. Base-treated and untreated separators were manufactured as described above using vials into which sodium hydroxide and barium hydroxide (3N solution) were introduced.

[0028] Next, these vials, including the separator, were placed in a vacuum oven for at least 48 hours to ensure they were completely dried at a temperature of 125°C.

[0029] To better understand the HF capture capability of the treated separator element, a "dummy" electrolyte was prepared and used in this experimental analysis. In actual electrolytes, the main salt, LiPF6, causes cyclic reactions, complicating the results. Instead, the main components of conventional electrolytes, namely ethyl methyl carbonate (EMC) and ethylene carbonate (EC) (both sourced from Sigma Aldrich), were used. To prepare the dummy electrolyte, EC was heated to its melting point and then added to a glass flask. EMC was added to the flask so that the ratio of the two chemicals was 1:1 by volume, and thoroughly mixed. A portion was divided from the masterbatch of the dummy electrolyte and placed in smaller flasks. HF solution was "added" to these portions and thoroughly mixed until the desired initial HF concentration for each experiment was reached.

[0030] Next, the sample vials containing the separators were removed from the oven, immediately placed in with the dummy electrolyte, and sealed to minimize contamination of the samples from ambient humidity in the laboratory space. While measuring the pH at the end of the test, 7 mL of dummy electrolyte was used for all samples to ensure the separators were fully moistened and to obtain more solution than necessary for sample collection. The vials were sealed with PTFE caps. The sealed vials were stored in a Bel-Art Dry Keeper Desiccant Cabinet for the specified exposure time.

[0031] At the end of the exposure time, samples were taken one by one for analysis. To avoid probe damage and ensure measurements within a reasonable pH range, 10 mL of water was added to each sample and mixed thoroughly. A Mettler Toledo SevenCompact S220 pH / Ion meter was used in this study. For analysis, the mixed samples were left uncapped, and a pre-calibrated probe was immersed in the samples.

[0032] (Results and Discussion) The first analysis relates to measuring the pH level of sample separators. The raw data is shown in the graph of Figure 1. The untreated separator shows a tendency for pH to increase, but the level is far lower compared with the hydroxide-treated separator. Thus, there is a clear tendency that pH increases as the separator surface area increases. pH can be converted into hydrogen ion concentration [H + using the following formula (Equation 1). (Equation 1) [H + =10 -pH

[0033] Accordingly, Figure 2 shows a similar upward graph trend for the treated separator relative to the concentration of trapped [H + . The following formula (Equation 2) essentially shows such a result with respect to the measured results for the sample separators (the treated separator shows a clear increase in trapped acid). (Equation 2) [H + ブランクサンプル -[H + サンプル =[H + 捕捉された

[0034] Figure 3 is a graph that uses further data from the above formulas and measured values regarding the concentration difference from the blank (untreated sample) to the caustic-treated separator. Here again, a clear tendency demonstrates the advantages of the disclosed separator example, and it is also clear to some extent that untreated separators inherently exhibit slight acid trapping capability, albeit at a level far lower than that of the disclosed base-treated separators.

[0035] ​​​Figure 4 shows a graph of the actual molars of HF captured against the surface area of ​​the separators (treated and untreated). Here again, as expected in relation to the acid capture measurements described above, such results for the molars of captured HF indicate that the basic-treated separators of this disclosure far exceed the capture capacity of all untreated separators. Furthermore, sodium hydroxide treatment appears to increase the capture level compared to barium hydroxide-treated separators.

[0036] Since only HF (in known amounts and concentrations) was added to the dummy electrolyte, the following assumptions were made to create this graph. (Math 3) [H + ]=[HF] Convert to moles using the total amount of dummy electrolyte and water. (Math 4) [HF] * 0.017 [L] = Moles of HF Furthermore, such HF capture capability, based on the weight of the separator in question, can be calculated using the following equation (Equation 5) to convert it to the mass of the separator.

number

number

[0037] In summary, the amount of HF capture capacity increases as the surface area (or mass) of the separator increases. The amount of HF captured by the untreated separator is significantly less than that captured by the base-treated separator, providing evidence that base treatment of the separator affects its capture capacity. Both base treatments were performed by introducing an excess of 3N base into the separator (with appropriate wastewater). That is, the (-OH) groups present in each base were equal. The NaOH-treated separator was Ba(OH) 2There are two possible explanations for why it performed better. The first is that barium exhibits a higher charge, making it difficult to release its second (-OH) group. The second is that the smaller NaOH group is more permeable to the separator. Both the Ba and Na groups show similar slopes, indicating that the capture rate is higher than that of the untreated separator, with increasing separator volume. This indicates uniform functionalization of the separator surface.

[0038] Therefore, when the separator is treated with a base, its HF capture capability is enhanced. Standardized separator treatment (3N vs. 3M solution) provides assurance that the same number of (-OH) groups have been introduced into the separator environment. In fact, the disclosed base-treated separator exhibits HF capture capability and capacity that have not been previously investigated in the field of rechargeable energy storage devices. Thus, improvements such as those described above using such treated separator elements can result in batteries that are safer and have better performance.

[0039] As this disclosure has been described in detail, it will be clear that those skilled in the art can modify and alter this disclosure without departing from its scope. Therefore, the scope of this disclosure should be determined solely by the appended claims.

Claims

1. A battery separator for lithium-ion battery cells, The aforementioned battery separator exhibits counter-ions on its surface, The aforementioned counterions have a maximum pK of 6.0 ｂ Selected from the group consisting of ions conjugated by bases having a level, A battery separator for lithium-ion battery cells, characterized in that the battery separator exhibits hydrofluoric acid capture properties.

2. The battery separator according to claim 1, characterized in that the aforementioned pair ion is selected from sodium ions, magnesium ions, potassium ions, barium ions, and calcium ions.

3. A battery comprising the battery separator described in claim 1, A battery characterized in that the battery separator is positioned between the cathode and the anode.

4. A battery comprising the battery separator described in claim 2, A battery characterized in that the battery separator is positioned between the cathode and the anode.

5. The battery separator according to claim 1, characterized in that the counterions are applied during or after the manufacture of the battery separator.

6. The battery separator according to claim 3, characterized in that the aforementioned counterion is a sodium ion.

7. The aforementioned counterions have a maximum pK of 4.0 ｂ The battery separator according to claim 1, characterized in that it is selected from the group consisting of ions that are added by a base having a level.

Images