Copolyester film for use as a separator in metal ion batteries

Abstract

1. A copolyester film comprising a copolyester comprising repeat units derived from a diol, a dicarboxylic acid, and a poly(alkylene oxide), the copolyester film further comprising a first metal ion-containing component selected from a conductive ceramic particulate material, and may further comprise additional metal ions from one or more sources other than the conductive ceramic particulate material.

Description

[Technical Field]

[0001] The present invention relates to copolyester films and other articles produced therefrom, as well as methods for synthesizing them. In particular, the present invention relates to copolyester films exhibiting properties necessary for use as separators in metal-ion batteries, especially lithium-ion batteries.

[0002] Lithium-ion batteries are widely used in the field of rechargeable batteries, which are expected to continue growing in the foreseeable future, partly due to the increasing demand for home appliances and renewable energy storage devices. During battery operation (i.e., between charging and discharging), lithium ions move between the cathode and anode. Commercially available lithium-ion batteries are typically supplied as wet-cell batteries containing a liquid or gel electrolyte with a lithium salt, as well as a microporous separator. The microporous separator is placed between and in contact with the two active solid electrodes. Generally, microporous separators for lithium-ion batteries have a thickness of about 20 μm to about 25 μm and are based on stretched polyolefin films (particularly polyethylene and polypropylene). The separator allows the movement of lithium ions by enabling the movement of the liquid or gel electrolyte through its pores, while preventing direct electrical contact between the cathode and anode in the battery. However, concerns remain regarding the safety of wet-cell lithium-ion batteries, which are known to ignite or even explode. The porous network structure can induce the growth of lithium dendrites between the cathode and anode, potentially leading to short circuits, thermal runaway, and flammability in the battery. The risk of flammability is exacerbated by the relatively low glass transition and melting temperatures of polyolefins. A further drawback of polyolefin films as separators is their relatively low mechanical strength, particularly the relatively low tensile strength in the transverse direction of biaxially oriented films.

[0003] Dry cell batteries have been developed that mitigate some of the safety concerns mentioned above. These dry cell batteries include a solid separator between the anode and cathode, which prevents contact between the electrodes and acts as a physical barrier to dendrite growth. In dry cell batteries, the potentially flammable liquid electrolyte is eliminated. Therefore, since the separator must function effectively as both a separator and an electrolyte, in the case of lithium-ion batteries, the separator must allow the movement of lithium ions within its structure. Such lithium-conductive solid separators can be broadly classified into two groups.

[0004] The first group consists of LiPON (lithium phosphate nitride, Li2PO2N), LLTO (lithium lanthanum titanium oxide), or LGPS (Li 10 GeP2S 12 The focus is on the use of inorganic lithium-ion conductors, such as ceramics. Typically, ceramic separators have a maximum capacity of 10 -1 Scm -1 Such conductivity is possible. Such inorganic lithium-ion conductors are supplied as thin films and are generally deposited using the sputtering method. However, the deposition rate is slow, and processing is limited to coin cells with small surface areas. Furthermore, since the volumes of the cathode and anode change during battery operation, the separator needs to accommodate these volume fluctuations. If the separator is too rigid, it may be damaged during charge-discharge cycles or its cycle performance may be limited. This is particularly problematic in the case of rigid ceramic separators. The rigid and brittle nature of ceramic separators makes them prone to cracking in ceramic films, which can cause problems during the manufacturing of the separator and during cell winding and battery assembly.

[0005] The second group focuses on the use of polymer films containing polymer matrices and lithium salts such as LiClO4. WO2019 / 186173 discloses a thin polymer film comprising a copolyester containing repeating units derived from aliphatic diols, aromatic dicarboxylic acids, and poly(alkylene oxides), further comprising lithium ions derived from lithium salts. The conductivity of such separators at room temperature is generally lower than that of ceramic conductors.

[0006] The present invention aims to address one or more of the aforementioned problems. In particular, an object of the present invention is to provide an improved film for use as a separator in a metal-ion solid battery, i.e., a metal-ion battery containing the above-described dry cell configuration or a liquid or gel electrolyte. In particular, an object of the present invention is to provide an improved film for use as a separator in a metal-ion solid battery. In particular, an object of the present invention is to provide a film that at least maintains, and preferably improves, the conductivity of an existing metal conductive separator, while simultaneously exhibiting good mechanical strength, particularly reduced brittleness and / or improved flexibility compared to a ceramic separator. In particular, an object of the present invention is to provide a film that at least maintains, and preferably improves, the conductivity of an existing metal conductive separator, exhibits good mechanical strength, particularly reduced brittleness and / or improved flexibility compared to a ceramic separator, while simultaneously ensuring ease of film formation and improving manufacturing efficiency and economics. The present invention further aims to provide a film separator that can reduce the volume and / or weight of a battery by reducing its thickness and / or weight while at least maintaining mechanical performance. It is desirable that the film separator is not brittle and exhibits flexibility.

[0007] The present invention relates particularly to lithium-ion batteries. Accordingly, as used in the preceding paragraphs and in the corresponding contexts below, the terms “metal ion,” “metal,” “metal conductive separator,” and “metal-ion battery” preferably refer to “lithium ion,” “lithium,” “lithium conductive separator,” and “lithium-ion battery,” respectively. However, the present invention is also applicable to other rechargeable metal-ion batteries containing sodium, potassium, calcium, magnesium, and aluminum, particularly sodium, magnesium, and aluminum, and particularly sodium.

[0008] According to a first aspect, a copolyester film is provided comprising a copolyester containing repeating units derived from a diol, a dicarboxylic acid, and poly(alkylene oxide), further comprising a first metal ion-containing component selected from a conductive ceramic particle material, and further comprising additional metal ions from one or more sources other than the conductive ceramic particle material.

[0009] It will be understood that the metal of the first metal ion-containing component of the film for use in metal ion batteries is preferably the same as the metal of the additional metal ion (hereinafter also referred to as the second metal ion-containing component).

[0010] Preferably, the first metal ion-containing component is a first lithium ion-containing component, in which case the additional metal ion is preferably an additional lithium ion. Alternatively, the first metal ion-containing component is a first sodium ion-containing component, in which case the additional metal ion is preferably an additional sodium ion.

[0011] Preferably, the copolyester film contains the additional metal ions. If present, the additional metal ions are preferably selected from metal salts, preferably from lithium salts or sodium salts, and preferably from lithium salts, in the form of a second metal ion-containing component.

[0012] Accordingly, in a preferred embodiment, a first aspect of the present invention provides a copolyester film comprising the copolyester, a first metal ion-containing component selected from conductive ceramic particle material, and a second metal ion-containing component selected from metal salts. It will be understood that the first and second metal ion-containing components are different from each other.

[0013] In a particularly preferred embodiment, a first aspect of the present invention provides a copolyester film comprising a copolyester, a first lithium ion-containing component selected from conductive ceramic particle material, and a second lithium salt ion-containing component selected from lithium salts. It will be understood that the first and second lithium ion-containing components are different from each other.

[0014] In an alternative embodiment, a first aspect of the present invention provides a copolyester film comprising the copolyester, a first sodium ion-containing component selected from conductive ceramic particle material, and a second sodium ion-containing component selected from sodium salts. It will be understood that the first and second sodium ion-containing components are different from each other.

[0015] The copolyester film of the present invention is suitable as a separator, and particularly suitable as a solid electrolyte. Therefore, the copolyester film exhibits volume conductivity, not merely surface conductivity. The inventors have surprisingly found that the film of the present invention is suitable as a solid separator exhibiting an excellent combination of good conductivity and high mechanical strength (particularly reduced brittleness and / or improved flexibility), while achieving such performance at relatively thin thicknesses and enabling efficient and reliable manufacturing. Such a separator exhibits excellent dimensional stability, especially at high temperatures, and can tolerate volume fluctuations of the electrodes during normal battery cycles.

[0016] As used herein, the term "copolyester" refers to a polymer containing ester bonds and derived from three or more comonomers. The copolyesters described herein are thermoplastic.

[0017] Suitable dicarboxylic acids for copolyesters include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, and naphthalenedicarboxylic acid (2,5-, 2,6-, or 2,7-naphthalenedicarboxylic acid, etc.), as well as aliphatic dicarboxylic acids such as succinic acid, sebacic acid, adipic acid, and azelaic acid. Alicyclic dicarboxylic acids may also be used. Other suitable dicarboxylic acids include 4,4'-diphenyldicarboxylic acid and hexahydro-terephthalic acid. Preferably, the dicarboxylic acid used in the present invention is an aromatic dicarboxylic acid, preferably terephthalic acid or isophthalic acid, and preferably terephthalic acid.

[0018] The copolyester preferably comprises at least one aromatic dicarboxylic acid, preferably terephthalic acid, isophthalic acid, or naphthalenedicarboxylic acid, preferably terephthalic acid or isophthalic acid, and preferably terephthalic acid. In the most preferred first embodiment, the dicarboxylic acid component comprises simply one aromatic dicarboxylic acid. In the second embodiment, the dicarboxylic acid component comprises a first aromatic dicarboxylic acid (preferably terephthalic acid or isophthalic acid, preferably terephthalic acid) and a second dicarboxylic acid. The second dicarboxylic acid may be selected from aliphatic dicarboxylic acids such as succinic acid, sebacic acid, adipic acid, or azelaic acid, and in one embodiment, the second dicarboxylic acid is azelaic acid.

[0019] Suitable diols for copolyesters include acyclic, alicyclic, and aromatic dihydroxy compounds. Preferred diols have 2 to 15 carbon atoms and include ethylene, propylene, isobutylene, tetramethylene, 1,4-pentamethylene, 2,2-dimethyltrimethylene, hexamethylene glycol and decamethylene glycol, dihydroxycyclohexane, cyclohexanedimethanol, resorcinol, hydroquinone, and 1,5-dihydroxynaphthalene. Aliphatic diols are preferred, particularly acyclic aliphatic diols containing 2 to 8 carbon atoms, and especially aliphatic diols containing 2 to 4 carbon atoms. Unbranched aliphatic diols are preferred. The diol is preferably selected from ethylene glycol, 1,3-propanediol, and 1,4-butanediol, more preferably selected from ethylene glycol and 1,4-butanediol, and most preferably ethylene glycol. Alicyclic glycols such as 1,4-cyclohexanedimethanol (CHDM) may also be used. Ester-forming derivatives homogeneous with the diol may be used instead of the diol. The copolyester preferably comprises only one diol residue. In one embodiment, at least 90 mol%, preferably at least 95 mol%, preferably at least 98 mol%, and preferably at least 99 mol%, of the diol fraction consists of one diol.

[0020] A suitable poly(alkylene oxide) for copolyester is preferably C2-C 15 Preferably C2-C 10, preferably selected from C2-C6 alkylene chains. The poly(alkylene oxide) may be selected from polyethylene glycol (PEG), polypropylene glycol (PPG), and poly(tetramethylene oxide) glycol (PTMO), preferably polyethylene glycol. Ethylene oxide-terminated poly(propylene oxide) segments can also be used. In one embodiment, the copolyester contains only one type of poly(alkylene oxide) residue. In an alternative embodiment, the copolyester contains two or more types of poly(alkylene oxide) residues, such as a mixture of polyethylene glycol (PEG) and polypropylene glycol (PPG).

[0021] The number average molecular weight (M N ) of the poly(alkylene oxide) glycol is preferably about 200 g / mol to 20,000 g / mol, preferably about 200 g / mol to about 6000 g / mol, preferably about 200 g / mol to about 5000 g / mol, preferably about 5000 g / mol or less, preferably about 4000 g / mol or less, preferably about 400 g / mol to about 3900 g / mol, preferably at least about 500 g / mol, preferably about 500 g / mol to about 3800 g / mol, most preferably about 500 g / mol to about 3700 g / mol, preferably about 800 g / mol to about 3600 g / mol, preferably about 1000 g / mol to about 3600 g / mol, preferably about 2000 g / mol to about 3500 g / mol, and preferably about 3350 to about 3450 g / mol, and preferably about 3350 or about 3450 g / mol. The number average molecular weight (M N ) of the poly(alkylene oxide) is preferably at least about 200 g / mol, preferably at least about 400 g / mol, preferably at least about 500 g / mol, and preferably at least about 800 g / mol, for example at least about 1000 g / mol. The number average molecular weight (M NThe g / mol content is preferably about 20,000 g / mol or less, preferably about 5,000 g / mol or less, preferably about 4,000 g / mol or less, and preferably about 3,800 g / mol or less, for example, about 3,700 g / mol or less.

[0022] It has been found that when the molecular weight of poly(alkylene oxide) is too high, copolymerization with dicarboxylic acids and aliphatic diols becomes more difficult, particularly in the melt extrusion process, to form copolyesters with sufficiently high melt viscosity for reliable film formation. Furthermore, when the molecular weight of poly(alkylene oxide) is too high, its conductivity may decrease.

[0023] Unless otherwise indicated in the context, the term molecular weight as used herein refers to the number-average molecular weight (M) measured by the method described herein. N ) refers to.

[0024] The multivariance index PDI (or variance D) is M W / M N It is defined as follows: Here, M W The polydispersity index, which is the weight-average molecular weight, measures the uniformity (or heterogeneity) of the sizes of different macromolecules, including polymers (a mixture of macromolecules of different sizes). A composition with a polydispersity index of 1 (i.e., monodisperse) consists of macromolecules (such as dendrimers) each of the same size. Monodisperse compositions of macromolecules are typically produced by non-polymerization processes and are not typically referred to as polymers.

[0025] The poly(alkylene oxide) of the copolyester preferably has a polydispersity index of 1 or more, preferably at least about 1.01, preferably at least about 1.1, preferably at least about 1.2, and preferably about 2.0 or less, preferably about 1.8 or less, preferably about 1.6 or less, and preferably about 1.01 to about 2.0, preferably about 1.1 to about 1.8, and preferably about 1.2 to about 1.6.

[0026] Copolyesters may be block (segmented) copolymers containing alternating, repeating random-length sequences linked by ester bonds. Such copolyesters exhibit semicrystalline (or hard) segments derived from aromatic dicarboxylic acids and aliphatic diols, and amorphous (or soft) segments derived from poly(alkylene oxides). Hard segments consist of repeating units of [R1-OC(=O)-AC(=O)-O], where R1 is derived from an aliphatic diol and A is an aromatic ring (preferably phenyl or naphthyl) derived from the aromatic dicarboxylic acid as defined above. Soft segments consist of repeating units of [RO], where R is the alkylene chain of poly(alkylene oxide). Soft segments may be terminally modified with the aromatic dicarboxylic acid via ester bonds.

[0027] In further embodiments, the copolyester is a random copolymer in which aromatic dicarboxylic acids, aliphatic diols, and poly(alkylene oxide) units are arranged in a random sequence within the copolyester main chain.

[0028] Between these two extremes, random copolymers and block copolymers, there exist copolyesters referred to herein as “block-like” copolymers. In block-like copolymers, poly(alkylene oxide) units are scattered among aromatic dicarboxylic acid units to a considerably greater extent than in block copolymers, and as a result, the aforementioned crystalline (or hard) segments are, on average, significantly shorter than in block copolymers. The arrangement of comonomer units in the copolymer chain, i.e., the degree of randomness of the copolyester, is determined using prior art known in the art, preferably as described herein. 13 This can be measured by 13C NMR spectral analysis. Copolyesters can be characterized as block, block-like, or random copolyesters by quantifying the degree of randomness B using a value of 0 representing a pure block copolymer and a value of 1 representing a statistically random copolymer, as defined by the Bernoulli model.

[0029] Preferably, B is in the range of about 0.1 to 1.0, preferably about 0.2 to about 0.95, preferably about 0.3 to about 0.9, preferably about 0.4 to about 0.8, for example, about 0.5 to about 0.7. The copolyester preferably has a B value of at least about 0.1, preferably at least about 0.2, preferably at least about 0.3, and preferably at least about 0.4, for example, at least about 0.5. The copolyester preferably has a B value of 1.0 or less, preferably about 0.95 or less, preferably about 0.9 or less, preferably about 0.8 or less, and preferably about 0.7 or less.

[0030] Preferably, the copolymer of the present invention is a "block-like" copolyester or a random copolyester.

[0031] More preferably, the copolymer of the present invention is a "block-like" copolyester, which can be obtained by selecting the molecular weight of the poly(alkylene oxide) as described herein.

[0032] The molecular weight of poly(alkylene oxide) has been found to significantly influence the arrangement of comonomers in the copolymer and the characterization of the copolymer as a block, block-like, or random copolymer. Therefore, low molecular weight poly(alkylene oxide) promotes the formation of random copolymers, while high molecular weight poly(alkylene oxide) promotes the formation of block copolymers. Block copolymers typically exhibit a greater tendency to crystallize and a higher melting temperature compared to the corresponding random copolymers. While block copolymers require higher processing temperatures, this increases the risk of decomposition, so it is preferable to avoid higher melting temperatures in this invention. Furthermore, the increased tendency of pure block copolymers to crystallize can hinder the movement of metal ions within the copolymer structure, potentially reducing its conductivity; therefore, it is preferable to avoid this in this invention.

[0033] The poly(alkylene oxide) preferably constitutes about 0.1 to about 80% by weight, preferably about 5 to about 78% by weight, preferably about 10 to about 75% by weight, preferably about 12 to about 65% by weight, preferably about 15 to about 60% by weight, and preferably about 16 to about 55% by weight of the total weight of the copolyester.

[0034] Preferably, the poly(alkylene oxide) constitutes at least about 0.1% by weight, preferably at least about 5% by weight, preferably at least about 10% by weight, preferably at least about 12% by weight, preferably at least about 15% by weight, preferably at least about 16% by weight, preferably about 80% by weight or less, preferably about 78% by weight or less, preferably about 75% by weight or less, preferably about 65% by weight or less, preferably about 60% by weight or less, and preferably about 55% by weight or less, of the total weight of the copolyester.

[0035] If the copolyester contains repeating units derived from a diol (preferably ethylene glycol), terephthalic acid, and poly(alkylene oxide), the poly(alkylene oxide) is preferably present in an amount of about 5 to about 30% by weight, preferably about 10 to about 25% by weight, and preferably about 15 to about 20% by weight, of the total weight of the copolyester.

[0036] If the copolyester contains repeating units derived from a diol (preferably ethylene glycol), isophthalic acid, and poly(alkylene oxide), the poly(alkylene oxide) is preferably present in an amount of about 35 to about 65% by weight, preferably about 40 to about 60% by weight, and preferably about 45 to about 55% by weight, of the total weight of the copolyester.

[0037] The amount of copolyester present in the copolyester film is preferably about 99.9% by weight or less, preferably about 95% by weight or less, preferably about 92% by weight or less, and preferably about 90% by weight or less, of the total weight of the copolyester film. Preferably, the amount of copolyester present in the copolyester film is at least about 40% by weight, preferably at least about 50% by weight, preferably at least about 65% by weight, and preferably at least about 80% by weight, of the total weight of the copolyester film. Therefore, the amount of copolyester present is preferably about 40% to about 99.9% by weight, preferably about 50% to about 95% by weight, preferably about 65% to about 92% by weight, and preferably about 80% to about 90% by weight, of the total weight of the copolyester film.

[0038] Preferably, the copolyester is the only polyester present in the film.

[0039] The copolyester film of the present invention contains a first metal ion-containing component selected from conductive ceramic particle materials. Preferably, the copolyester film of the present invention contains a first lithium ion-containing component selected from conductive ceramic particle materials. One or more conductive ceramic particle materials may be present.

[0040] Those skilled in the art will understand that ceramic materials are inorganic nonmetallic solids containing both metallic and nonmetallic elements, formed or densified by heating at high temperatures. Ceramic materials are typically rigid, brittle, corrosion-resistant, have low chemical reactivity, and high melting points. The ceramic materials referred to herein may be crystalline or vitreous. The ceramic particle materials used in the present invention are conductive. The present invention will be described below primarily in relation to lithium-ion-containing conductive ceramic particle materials, but the technical principles are generally applicable to other metal-ion-containing conductive ceramic particle materials.

[0041] Any suitable lithium-ion-containing conductive ceramic particle material can be used, and in particular, NASICON-type ceramic particle materials (such as lithium-ion-containing conductive glass ceramic particle materials), LISICON-type ceramic particle materials, perovskite-type oxide ceramic particle materials, garnet-type oxide ceramic particle materials, lithium phosphooxynitride (LIPON)-type ceramic particle materials, and lithium aluminum silicate (LAS) ceramic particle materials can be used.

[0042] As is known in the art, NASICON (sodium superionic conductor) materials refer to a group of solids having the chemical formula Na 1+x Zr2Si x P 3-x O 12 (0 < x < 3), as well as similar compounds in which Na, Zr, and / or Si are replaced by equivalent elements. Thus, in connection with the most preferred embodiments of the present invention, sodium is replaced by lithium. Particularly suitable lithium-containing NASICON-type ceramic particle materials may have the general formula LiM y (PO4)3, where M represents a polyvalent metal ion. For example, M can be selected from one or more of Al, Si, Ti, Zr, Ge, Sn, and Hf. Other suitable lithium-containing NASICON-type ceramic particle materials may have the general formula Li 1+x M x Ti 2-x (PO4)3 (LATP), where M represents a trivalent cation selected from one or more of Al, Sc, Y, and La. Other suitable lithium-containing NASICON-type ceramic particle materials may have the general formula Li 1+x Al x Ge 2-x (PO4)3 (LAGP), for example, where x is 0.5.

[0043] Particularly preferred are lithium-ion-containing conductive glass ceramic particle materials having a NASICON structure. A preferred particle material is one commercially available from Ohara Inc. under the trade name "LICGC". Another preferred particle material is one commercially available from Ohara Inc. as LICGC(trademark)PW-01 powder, which is Li 1+x+y Al x Ti 2-x Si y P 3-y O 12 It is understood to have a main crystalline phase and a composition of Li2O-Al2O3-SiO2-P2O5-TiO2. A more preferred particulate material is commercially available from Ohara Inc. as LICGC(trademark)AG-01, which is Li 1+x+y Al x (Ti,Ge) 2-x Si y P 3-y O 12 It is understood to have a main crystalline phase and a composition of Li2O-Al2O3-SiO2-P2O5-TiO2-GeO2.

[0044] As is well known in the art, LISICON (lithium superionic conductor) material has the chemical formula Li 2+2x Zn 1-x This refers to a group of solids containing GeO4. Similar to NASICON-type materials, other elements (usually equivalent elements) and Li, Zn, and / or Ge can be substituted. A suitable LISICON-type particulate material is Li 2+2x Zn 1-x Ge4O 16 Li 14 ZnGe4O 16 Li (3+x) Ge x V (1-x) O4, Li (4-x) Si (1-x) P x O4 and formula Li (4-x) Ge (1-x) P x S4Li 10 GeP2S 12 It can be selected from thio-LISICONs such as those having the following properties, where x is between 0 and 1 in the formula.

[0045] Suitable perovskite-type oxide particle materials include Li 3x La (2 / 3)-x TiO3 (LLTO) and Li 3x La 1 / 3-x You can choose from TaO3.

[0046] Suitable garnet-type oxide particle materials include those with the general formula Li 7-3y-x La3Zr 2-x M1 y M2 x O 12 (In the formula, M1 represents a trivalent cation such as Al and Ga, and M2 represents a pentavalent cation such as Nb and Ta, where x≧0 and y≦2); Li5La3M2O 12 (In the formula, M represents Nb and / or Ta); Li6ALa2M2O 12 (wherein A represents Ca, Sr, and / or Ba, and M represents Nb or Ta); or Li 6.5 La 2.5 Ba 0.5 ZrTaO 12 It may have.

[0047] Suitable LIPON-type ceramic particle materials include Li2PO2N and other materials with the general formula Li x PO y N z It may have.

[0048] Suitable LAS ceramic particle materials can be selected from AlLiO6Si2.

[0049] Regarding sodium ion-containing ceramic particle materials, particularly preferred are NASICON-type ceramic particle materials (such as sodium ion-containing conductive glass ceramic particle materials), beta-alumina and beta''-alumina phases Na2O·nAl2O3 (wherein 5≦n≦11), rare earth sodium silicate, and Na ion-conductive oxyhalide glass. A preferred NASICON-type ceramic particle material has the general formula Na3Zr2Si2PO 12 , NaTi2(PO4)3, NaGe2(PO4)3, or Na1+x [Sn x Ge 2-x It is a NASICON structure oxide that may have [(PO4)3]. A suitable rare earth sodium silicate is one with the general formula Na5MSi4O 12 The formula has the following properties, where M is Y, Sc, Lu, and / or any trivalent rare earth cation. A suitable Na ion-conducting oxyhalide glass may be NaI-NaCl-Na2O-B2O3.

[0050] Preferably, the median particle size in the volume distribution of the conductive ceramic particle material (the equivalent spherical diameter corresponding to 50% of the total particle volume, read on a cumulative distribution curve relating particle volume % versus diameter – usually referred to as the "Dv50" or "D50" value) is in the range of 0.01 to 5 μm, preferably 0.05 to 3 μm, preferably 0.1 to 2 μm, preferably 0.2 to 1.5 μm, and preferably 0.4 to 1.0 μm. The particle size can be measured by laser diffraction (preferably Fraunhofer diffraction). A particularly preferred method is the Mastersizer (e.g., 3000) available from Malvern. The median particle size may also be determined by plotting a cumulative distribution curve representing the percentage of particle volume below the selected particle size and measuring the 50th percentile.

[0051] The amount of the metal ion-containing conductive ceramic particle material present in the copolyester film is preferably about 60% by weight or less, preferably about 50% by weight or less, preferably about 35% by weight or less, preferably about 20% by weight or less, and preferably at least about 0.1% by weight, preferably at least about 5% by weight, preferably at least about 8% by weight, and preferably at least about 10% by weight, of the total weight of the copolyester film. Therefore, the amount of conductive ceramic particle material present is preferably about 0.1% to about 60% by weight, preferably about 5% to about 50% by weight, preferably about 8% to about 35% by weight, and preferably about 10% to about 20% by weight, of the total weight of the copolyester film.

[0052] The metal ion-containing conductive ceramic particle material is held within the polymer matrix of the film.

[0053] As described above, the copolyester film of the present invention preferably contains additional metal ions from one or more sources other than the conductive ceramic particle material. If the conductive ceramic particle material is a lithium-ion-containing conductive ceramic particle material, the copolyester film preferably contains additional lithium ions from one or more sources other than the conductive ceramic particle material. If the conductive ceramic particle material is a sodium-ion-containing conductive ceramic particle material, the copolyester film preferably contains additional sodium ions from one or more sources other than the conductive ceramic particle material. These additional metal ions are referred to herein as a second metal ion component, for example, a second lithium ion component or a second sodium ion component. It will be understood that the first metal ion-containing component and the second metal ion component are different from each other. The second metal ion component is preferably a metal ion-containing component selected from metal salts. The present invention will be described below mainly in relation to lithium salts, but the technical principles are generally applicable to other metal salt materials.

[0054] Any suitable lithium salt may be used. One or more different types of lithium salts may be used. Preferably, the lithium salt is selected from lithium salts suitable for use in lithium-ion batteries, such as lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium thiocyanate (LiSCN), lithium hexafluoroarsenate (LiAsF6), lithium trifluoromethanesulfonate (LiCF3SO3), lithium bromide (LiBr), lithium iodide (LiI), lithium bis(trifluoromethanesulfonimide) (LiN(CF3SO2)2), lithium tris(trifluoromethylsulfonyl)methidolithium (LiC(CF3SO2)3), lithium orthosilicate, lithium trifluoroacetate (LiCF3CO2), and lithium bis(fluorosulfite)amide (LiN(FO2S)2).

[0055] When forming a copolyester film using a solvent casting method, it is preferable that the metal ions be derived from a metal salt that has high solubility in the solvent used in the solvent recasting step. Therefore, in the case of lithium-ion batteries, a particularly preferred lithium salt is lithium trifluoromethanesulfonate (LiCF3SO3).

[0056] Metal salts (including preferred lithium salts) (i) Aromatic carboxylic acids, preferably aromatic dicarboxylic acids, preferably terephthalic acid or isophthalic acid; (ii) an aliphatic carboxylic acid including an aliphatic dicarboxylic acid, preferably acetic acid, glycolic acid, or succinic acid; (iii) Carbonated water; (iv) Phenolic acid, preferably salicylic acid; (v) Perchloric acid or phosphoric acid, especially mineral acids such as phosphoric acid; and (vi) Boric acid, preferably bis(oxalic acid)boric acid, may be selected.

[0057] Optionally, the metal salt is selected from the metal salts (i) to (v) provided above.

[0058] Therefore, suitable lithium salts include dilithium terephthalate (DLTA), dilithium isophthalate, lithium glycolate, lithium benzoate, lithium acetate, lithium carbonate, lithium perchlorate, lithium orthosilicate, lithium phosphate, lithium salicylate, lithium succinate, and lithium bis(oxalato)borate.

[0059] Preferably, the metal salt is an organometallic salt.

[0060] In preferred embodiments, the metal salt is a salt of the aromatic dicarboxylic acid from which the copolyester is derived. Therefore, when the preferred copolyester is derived from terephthalic acid, the lithium salt is preferably selected from monolithium or dilithium terephthalate, and preferably dilithium terephthalate. The inventors have found that dilithium terephthalate is particularly preferred for reasons of thermal stability and cost. When the preferred copolyester is derived from isophthalic acid, the lithium salt is preferably selected from monolithium or dilithium isophthalate, and preferably dilithium isophthalate.

[0061] Other preferred metal salts can be selected from the alkoxylate esters of the aforementioned acids, particularly carboxylic acids, particularly dicarboxylic acids, particularly aromatic dicarboxylic acids, and particularly terephthalic acid. Such alkoxylate esters are preferably from aliphatic diols, preferably C 2-10 From an aliphatic diol, preferably C 2-6 They are derived from aliphatic diols, preferably from C2, C3, or C4 aliphatic diols, more preferably from ethylene glycol, 1,3-propanediol, and 1,4-butanediol, and more preferably from ethylene glycol.

[0062] A particularly suitable lithium salt has the following formula (I) and is referred to herein as dilithium bishydroxyethyl terephthalate (DL-BHET). [ka]

[0063] Preferably, the lithium salt is selected from lithium trifluoromethanesulfonate (LiCF3SO3), dilithium terephthalate, or dilithium bishydroxyethyl terephthalate. Preferably, the lithium salt is selected from dilithium terephthalate.

[0064] With respect to the sodium-containing embodiments of the present invention, any suitable sodium salt may be used. One or more different types of sodium salts may be used. It will be understood that the priorities and elements described with respect to lithium salts apply equally to sodium salts, except that lithium ions are replaced with sodium ions. Preferably, the sodium salt is selected from sodium nitrate (NaNO3), sodium perchlorate (NaClO4), sodium tetrafluoroborate (NaBF4), sodium hexafluorophosphate (NaPF6), sodium bis(trifluoromethanesulfonyl)imide (NaTFSI), sodium bis(trifluoromethane)sulfonimide (Na[N(CF3SO2)2]), sodium hexafluoroarsenate (V) (NaAsF6), sodium bis(oxalatoborate) ("NaBOB"), sodium halide (NaX) (wherein X is Cl, Br, or I), sodium thiocyanate (NaSCN), sodium pentacyanopropenide (NaPCPI), sodium tetracyanopyrrolate (NaTCP), and sodium tricyanoimidazolate (NaTIM).

[0065] In one embodiment, the metal ions of the second metal ion component are present and retained within the polymer matrix of the film by interactions between the metal cations and polarized electronegative oxygen atoms of the copolyester, preferably at least electronegative oxygen atoms of polyalkylene oxide units.

[0066] In a preferred embodiment, the metal ions of the second metal ion component are retained within the polymer matrix of the film by interactions between the metal cations and the anions of the metal salt. Thus, in this embodiment, the copolyester film contains a metal salt. Preferably at least a portion, preferably at least 50% by weight, preferably at least 60% by weight, preferably at least 70% by weight, preferably at least 80% by weight, preferably at least 90% by weight, preferably at least 95% by weight, preferably at least 99% by weight, and preferably substantially all of the metal ions of the second metal ion component are in the form of a metal salt. The metal salt is preferably a metal salt from which the metal ions are derived. The metal salt is selected from the metal salts described above, and the above priorities apply here. Thus, in this preferred embodiment, the metal salt is retained within the polymer matrix. In this embodiment, the metal salt is not part of the polymer backbone, i.e., it is not polymerized into the copolyester. In other words, in this preferred embodiment, the anions of the metal salt are not covalently bonded to the copolyester. In the preferred embodiment described above, where the metal salt is a salt of the same aromatic dicarboxylic acid from which the copolyester is derived, the metal-containing copolyester film described herein exhibits excellent thermal stability, which is thought to result from the compatibility between the form of the copolyester and the form of the metal salt.

[0067] The amount of metal ions in the second metal ion component in the copolyester film is preferably effective in providing a metal:O molar ratio of about 5:1 to about 1:50, preferably about 4:1 to about 1:50, preferably about 3:1 to about 1:50, preferably about 2:1 to about 1:50, preferably about 1:1 to about 1:40, preferably about 1:2 to about 1:30, and preferably about 1:4 to about 1:25, where the number of O atoms in this ratio is defined as the number of O atoms in the poly(alkylene oxide) residue, and the number of metal atoms in this ratio is defined as the number of metal atoms provided by the additional metal ions (i.e., the second metal ion component, excluding the first metal ion-containing component).

[0068] Preferably, the amount of the second metal ion component (i.e., preferably the metal salt) is about 40% by weight or less, preferably about 10% by weight or less, and preferably at least about 0.1%, preferably at least about 1%, and preferably about 0.1% to about 40% by weight, preferably about 1% to about 10% by weight, of the total weight of the copolyester film.

[0069] When the copolyester film of the present invention contains the second metal ion component, the total amount of the first metal ion-containing component and the second metal ion component is preferably about 60% by weight or less, preferably about 50% by weight or less, preferably about 35% by weight or less, preferably about 20% by weight or less, and preferably at least about 0.1% by weight, preferably at least about 5% by weight, preferably at least about 8% by weight, and preferably at least about 10% by weight, of the total weight of the copolyester film. Therefore, the total amount of the first metal ion-containing component and the second metal ion component present is preferably about 0.1% to about 60% by weight, preferably about 5% to about 50% by weight, preferably about 8% to about 35% by weight, and preferably about 10% to about 20% by weight, of the total weight of the copolyester film.

[0070] The copolyester, the first metal ion-containing component, and, if present, the second metal ion component, are the main components of the film and constitute, preferably at least about 65%, preferably at least about 75%, preferably at least about 85%, preferably at least about 95% by weight, and preferably at least about 98% by weight of the total weight of the film.

[0071] The copolyester film of the present invention may further contain any other additives conventionally used in the manufacture of polyester films. Therefore, antioxidants, UV absorbers, hydrolysis stabilizers, crosslinking agents, dyes, fillers, pigments, void-forming agents, lubricants, radical scavengers, heat stabilizers, combustion retarders and inhibitors, anti-blocking agents, surfactants, slip aids, gloss enhancers, decomposition accelerators, viscosity modifiers, and dispersion stabilizers may be incorporated as needed. Such additives can be introduced into the copolyester composition in conventional ways. For example, the additive(s) may be introduced by mixing with the monomer reactant from which the film-forming copolyester composition is derived, or the additive(s) may be mixed with the copolyester composition by rolling or dry mixing, or by compounding in an extruder, after which it is cooled and usually ground into granules or chips. Masterbatch technology may also be used.

[0072] In preferred embodiments, the film contains an antioxidant. Various antioxidants can be used, such as antioxidants that function by scavenging radicals or by decomposing peroxides. Suitable radical-scavenging antioxidants include hindered phenols, secondary aromatic amines, and hindered amines such as Tinuvin® 770 (Ciba-Geigy). Suitable peroxide decomposition antioxidants include trivalent phosphorus compounds such as phosphonites, phosphites (e.g., triphenyl phosphate and trialkyl phosphites), and thio synergists (e.g., esters of thiodipropionic acid such as dilauryl thiodipropionate). Hindered phenol antioxidants are preferred. A particularly preferred hindered phenol is tetrakis-(methylene 3-(4'-hydroxy-3',5'-di-t-butylphenylpropionate)methane, which is commercially available as Irganox® 1010 (Ciba-Geigy). Other preferred commercially available hindered phenols include Irganox® 1035, 1076, 1098, and 1330 (Ciba-Geigy), Santanox® R (Monsanto), Cyanox® antioxidant (American Cyanamid), and Goodrite® antioxidant (BF Examples include Goodrich. The concentration of antioxidants present in the film is preferably in the range of 50 ppm to 5000 ppm, more preferably in the range of 300 ppm to 1500 ppm, particularly in the range of 400 ppm to 1200 ppm, and particularly in the range of 450 ppm to 600 ppm, based on the weight of the copolyester. A mixture of more than one antioxidant may be used, in which case the overall concentration of the mixture is preferably within the aforementioned range. The incorporation of antioxidants into the copolyester may be achieved by conventional methods, preferably by mixing the copolyester with the monomer reactant to be derived before polycondensation, particularly at the end of a direct esterification or transesterification reaction.

[0073] In a more preferred embodiment, the film preferably comprises an inorganic particle filler selected from metalloid oxides (such as alumina, titania, zirconia, zinc oxide, talc, and silica), fired clay, alkali metal salts (such as calcium and barium carbonates and sulfates), and non-conductive ceramic particle materials. The inorganic filler should have a particle size smaller than the thickness of the film, preferably 10 μm or less, preferably about 5 μm or less, preferably about 2 μm or less, and preferably in the range of about 0.5 μm to about 2.0 μm. It will be understood that the inorganic particle filler (or in practice any other conventional additive described above) is distinct from the first or second metal ion-containing component described above, with different properties. In particular, the inorganic particle filler (or any other conventional additive described above) does not contain the metal ions of the first or second metal ion-containing component described above. For this reason, the inorganic particle filler is referred to as a “passive filler” because it cannot directly transport metal ions. Nevertheless, it has been surprisingly revealed that such passive fillers enhance the ionic conductivity generated by the first or second metal ion-containing component.

[0074] Accordingly, a preferred embodiment of the first aspect of the present invention provides a copolyester film comprising a copolyester containing repeating units derived from a diol, a dicarboxylic acid, and a poly(alkylene oxide), further comprising a first metal ion-containing component selected from conductive ceramic particle materials, and further comprising a passive filler.

[0075] Furthermore, in a more preferred embodiment of the first aspect of the present invention, a copolyester film is provided comprising a copolyester comprising repeating units derived from a diol, a dicarboxylic acid, and poly(alkylene oxide), further comprising a first metal ion-containing component selected from conductive ceramic particle material, further comprising a passive filler, and further comprising additional metal ions from one or more sources other than the conductive ceramic particle material and the passive filler.

[0076] Inorganic particulate fillers are always added to polyester films to improve handling and windability during manufacturing and downstream processes. For such purposes, fillers are usually used in relatively small amounts, and the total weight of the filler is generally about 2.5% by weight or less, preferably about 2.0% by weight or less, preferably about 1.0% by weight or less, more typically about 0.6% by weight or less, preferably about 0.3% by weight or less, based on the total weight of the copolyester film. However, in the present invention, the passive filler is preferably used in an amount of at least 5% by weight, preferably at least about 7% by weight, preferably at least about 10% by weight, and preferably about 5% to about 20% by weight, preferably about 7% to about 20% by weight, preferably about 7% to about 15% by weight, based on the total weight of the copolyester film.

[0077] When the film is formed by melt extrusion, the melt viscosity of the metal ion-containing copolyester obtained is preferably 100 Pa·s, preferably about 1000 Pa·s or less, preferably about 500 Pa·s or less, preferably about 300 Pa·s or less, preferably about 250 Pa·s or less, and preferably about 150 Pa·s at the desired processing temperature. A typical processing temperature at which the copolyester should exhibit such a melt viscosity is the temperature used in the production of the film described herein, preferably in the range of 200°C to 290°C, particularly 220°C to 280°C, preferably 275°C, and / or the copolyester is T M ~T M +10℃(T MSuch melt viscosity is observed at temperatures within the range of (where is the crystalline melting temperature of the copolyester). Excessively high melt viscosity can cause difficulties in film production and / or reduce the molecular weight of the final copolyester and / or increase the cost of film production, for example, by requiring the use of special film forming equipment. Also, excessively high melt viscosity may necessitate reducing the extruder's production rate to achieve stable film production, thereby reducing the efficiency and economics of production, or requiring an increase in the extrusion temperature to reduce the viscosity of the molten material (these, in turn, can lead to thermal decomposition of the polymer and loss of associated properties). If the melt viscosity is too low, reliable film formation and stretching may be difficult.

[0078] The copolyester films described herein are preferably oriented copolyester films, and preferably biaxially oriented copolyester films.

[0079] The films described herein are preferably self-supporting films, that is, films that can stand on their own without a support base.

[0080] The film thickness is preferably at least about 5 μm, preferably at least about 10 μm, preferably at least about 15 μm, and preferably at least about 20 μm. The film thickness is preferably about 200 μm or less, preferably about 150 μm or less, preferably about 100 μm or less, preferably about 85 μm or less, preferably about 70 μm or less, preferably about 50 μm or less, and preferably about 35 μm or less. Therefore, the film thickness is preferably about 5 μm to about 200 μm, preferably about 5 μm to about 150 μm, preferably about 10 μm to about 100 μm, preferably about 10 μm to about 85 μm, preferably about 15 μm to about 70 μm, preferably about 15 μm to about 50 μm, and preferably about 20 μm to about 35 μm.

[0081] Preferably, the transfilm ionic conductivity of the film is measured at 25°C and is at least about 10 -7S / cm, preferably at least about 10 -6 S / cm.

[0082] Preferably, the film-through ionic conductivity of the film is at least about 10 -7 S / cm, preferably at least about 10 -6 S / cm, preferably at least about 10 -5 S / cm.

[0083] The film should have a low shrinkage rate of preferably less than 20%, preferably less than 15%, preferably less than 10% at 100°C after 30 minutes. Preferably, the value of the low shrinkage rate is indicated for both (perpendicular) dimensions of the film (i.e., the longitudinal and transverse dimensions).

[0084] Preferably, the crystal melting point (T m ) of the film is higher than 175°C, preferably higher than 200°C, preferably higher than 210°C, preferably higher than 220°C. These temperatures are particularly preferred for PET-based copolyesters. In comparison, polyolefin films commonly used as microporous separators for lithium-ion batteries typically have a crystal melting point (T m ) of about 130°C to 150°C. Therefore, this relative increase in T m is advantageous since the films described herein are suitable for applications that require higher operating temperatures. Preferably, the crystal melting point (T m ) of the film is 270°C or lower.

[0085] Preferably, the film of the present invention exhibits a glass transition temperature (T g ) of about 50°C or lower, preferably about 45°C or lower, preferably about 40°C or lower. In the present invention, a lower T g is preferred because it promotes higher conductivity at the operating temperature of the film in the preferred end-uses described herein. The films of the present invention typically exhibit a T g of at least about -50°C, preferably at least about -30°C, and preferably at least about -10°C.

[0086] The films described herein are particularly suitable as solid separators in metal ion rechargeable batteries, especially dry cell batteries (also referred to herein as solid batteries).

[0087] According to a second aspect of the present invention, a method for producing a polyester film as defined in the first aspect of this specification, (i) Diol, dicarboxylic acid or its ester (preferably a lower alkyl (C) 1-4 The step of reacting a dicarboxylic acid with an ester, preferably a dimethyl ester, to form a bis(hydroxyalkyl)-ester; (ii) A step of polymerizing a bis(hydroxyalkyl) ester of a dicarboxylic acid by polycondensation in the presence of a poly(alkylene oxide) to form a copolyester; (iii) During the synthesis of the copolyester in step (i) and / or step (ii), and / or during a subsequent separate compounding or mixing step, a first metal ion-containing component selected from conductive ceramic particle material, and optionally additional metal ions from one or more sources other than conductive ceramic particle material, to form a copolyester composition; and (iv) The method is provided which preferably includes the step of forming a copolyester film from a copolyester composition by melt extrusion of the composition or by solvent casting of a dispersion or solution containing the copolyester composition.

[0088] The copolyesters described herein can be synthesized according to conventional techniques for manufacturing polyester materials. Thus, the copolyesters can be made by direct esterification or transesterification in a first step, followed by polycondensation in a second step. In an embodiment of direct esterification, a diol and a dicarboxylic acid are reacted directly, typically under high temperature (typically about 150 °C to 260 °C) and pressure (typically about 40 psi), in the presence of a base (e.g., sodium hydroxide), and water, which is a byproduct of the direct esterification reaction, is distilled off to form bis(hydroxyalkyl) carboxylate. When the direct esterification reaction is complete, a stabilizer (e.g., phosphoric acid) is added to neutralize the base. In an alternative embodiment, the copolyesters are prepared by a transesterification reaction pathway, which preferably involves reacting an ester of a dicarboxylic acid (preferably a lower alkyl (C 1-4 ) ester, preferably dimethyl ester) with a molar excess of diol at high temperature (typically in the range of about 150 °C to 260 °C), in the presence of a basic esterification catalyst (e.g., manganese(II) acetate tetrahydrate, Mn(OAc)2·4H2O), and distilling off methanol, which is a byproduct of the transesterification reaction, to form bis(hydroxyalkyl) carboxylate. Polymerization is carried out in a polycondensation step using a suitable catalyst, usually antimony trioxide, at high temperature (typically about 290 °C), typically under reduced pressure (e.g., about 1 mmHg), by continuously distilling off the byproduct(s). Poly(alkylene oxide) may be present after the start of the synthesis procedure because the dicarboxylic acid or dicarboxylic acid ester starting materials typically react selectively with the diol rather than with the poly(alkylene oxide), especially as the molecular weight of the poly(alkylene oxide) increases. However, preferably, the poly(alkylene oxide) is added after the start of the polycondensation step.

[0089] Preferably, the synthesis procedure further includes a solid state polymerization (SSP) step to increase the molecular weight of the copolyester and to increase and / or complete the polymerization of the poly(alkylene oxide) to the copolyester.

[0090] Therefore, the product of the polycondensation reaction (step (II)) preferably undergoes the SSP step. Solid-phase polymerization can be carried out, for example, in a fluidized bed fluidized with nitrogen, or in a vacuum fluidized bed using a rotary vacuum dryer. Suitable solid-phase polymerization techniques are disclosed, for example, in EP-A-0419400, the disclosures of which are incorporated herein by reference. Thus, SSP typically involves the crystalline melting point (T) of the polymer. M Although it is 10°C to 50°C lower than the glass transition temperature (T g The process is carried out at a temperature higher than (or, if the copolyester exhibits multiple glass transition temperatures, higher than the highest glass transition temperature). An inert atmosphere of dry nitrogen or a vacuum is used to prevent decomposition. In a preferred embodiment, solid-phase polymerization is carried out at 220°C under vacuum for 16 hours.

[0091] A first metal ion-containing component and an optional second metal ion-containing component may be introduced into the copolyester independently or together. When introduced independently, the first and second metal ion-containing components may be introduced simultaneously or sequentially. If either or both of the first and second metal ion-containing components contain multiple different compounds, the multiple compounds may be introduced into the copolyester independently or together, and when introduced independently, they may be introduced simultaneously or sequentially.

[0092] In one embodiment referred to herein as Embodiment A1, the first and second metal ion-containing components are introduced into the copolyester during the synthesis of the copolyester in step (i) and / or (ii). Preferably, the first and second metal ion-containing components are added to one or more reactants or reaction mixtures after the start of the synthesis procedure. Alternatively, the first and second metal ion-containing components are added to the reaction product of the direct esterification or transesterification step (i) before the polymerization step (ii).

[0093] In the second embodiment, referred to herein as Embodiment A2, the first and second metal ion-containing components are introduced into the copolyester during a separate compounding or mixing step.

[0094] In a third embodiment referred to herein as Embodiment A3, the first and second metal ion-containing components are introduced into the copolyester during different steps. For example, the second metal ion-containing component is introduced during the synthesis of the copolyester in step (i) and / or (ii) (preferably added to one or more reactants or reaction mixtures after the start of the synthesis), and the first metal ion-containing component is introduced during a separate compounding or mixing step.

[0095] The film may be formed by conventional melt extrusion techniques well known in the art. Generally speaking, this process includes the steps of extruding a polymer layer at a temperature within a range suitable for the melting temperature of the polymer, for example, in the range of about 250°C to about 300°C (or typically about 10°C or less, which is higher than the crystalline melting point of the polymer), quenching the extruded material, and preferably oriented the quenched extruded material.

[0096] Orientation may be carried out by any process known in the art for producing oriented films, such as inflation or flat film processes. Biaxial orientation is carried out by stretching the film in two mutually orthogonal directions within the plane of the film in order to achieve a satisfactory combination of mechanical and physical properties. Biaxial orientation may be carried out simultaneously or sequentially. Preferably, it is carried out simultaneously.

[0097] Simultaneous biaxial orientation may be performed, for example, in an inflation process by extruding a thermoplastic polyester tube, then quenching it, reheating it, and then expanding it with internal gas pressure to induce lateral orientation, and then drawing it out at a rate that induces longitudinal orientation. Particularly preferred simultaneous biaxial orientation processes are disclosed in EP-2108673-A and US-2009 / 0117362-A1, the disclosures of which are incorporated herein by reference.

[0098] Another preferred method is a flat film process in which the film-forming polyester is extruded through a slot die and rapidly quenched on a cooled casting drum, ensuring that the polyester is quenched into an amorphous state. Orientation is then carried out by stretching the quenched extruded product in at least one direction at a temperature above the glass transition temperature (or more) of the polyester. Sequential orientation may be carried out by first stretching the flat quenched extruded product in one direction, usually longitudinally, i.e., forward, via a film stretcher, and then stretching it transversely. The forward stretching of the extruded product is conveniently carried out on a set of rotary rolls or between two pairs of nip rolls, and the transverse stretching is carried out in a widthening device.

[0099] Stretching is generally carried out so that the dimensions of the orientation film are 2 to 7 times, preferably 2 to 5 times, more preferably 2.5 to 4.5 times, more preferably 3.0 to 4.5 times, and more preferably 3.5 to 4.5 times, the original dimensions in the stretching direction or each direction. Stretching is conventionally performed on the T of the copolyester composition. g A temperature higher than T g A temperature at least about 5°C higher than, preferably at least about 15°C higher, and preferably about T g +5℃~approx.T g +75℃, preferably about T g +5℃~approx.T gThe process is carried out at temperatures in the range of +30°C. Typically, stretching is performed at temperatures in the range of about 5°C to about 155°C, preferably about 5°C to about 110°C. If orientation in only one direction is required, a larger stretch ratio (e.g., up to about 8 times) may be used. This is preferable when balanced properties are desired, but it is not necessary to stretch equally in the longitudinal and transverse directions.

[0100] It is preferable to use a simultaneous biaxial stretching process, which is particularly advantageous for producing the thin film of the present invention.

[0101] The stretched film is made to induce the desired crystallinity of the copolyester, with a temperature above the glass transition temperature (or multiple temperatures) of the copolyester, but with a melting temperature (T M Dimensional stabilization may be performed by heat curing under a dimensional support at a temperature below ) and preferably dimensional stabilization. During heat curing, a small amount of dimensional relaxation may be performed in the transverse (TD) and / or longitudinal (MD) directions. The dimensional relaxation is up to 10%, more typically up to about 8%. Transverse dimensional relaxation is called "toe-in" in the art and typically involves a dimensional shrinkage of up to about 5%, typically about 2-4%. Longitudinal dimensional relaxation may be performed by prior art, but is a relatively more difficult process to achieve because low wire tension is required, especially in the sequential orientation process. For this reason, a simultaneous orientation process is used when MD relaxation is desired, and in this embodiment, simultaneous MD and TD relaxation is typically performed. The actual heat curing temperature and time will vary depending on the composition of the film and its desired final thermal shrinkage, but should not be chosen in a way that essentially degrades the toughness properties of the film, such as tear resistance. Within these constraints, preferred films are cured at a temperature about 80°C lower than the melting temperature of the film (i.e., T M -80℃)~T M A temperature approximately 10°C lower than (i.e., T M -10°C), preferably about T M -70℃~approx.T MThe film is heat-cured at -20°C. Therefore, the heat-curing temperature is preferably in the range of about 130°C to about 245°C, more preferably in the range of about 150°C to about 245°C, and more preferably in the range of at least 180°C, more preferably in the range of 190°C to 230°C. After heat-curing, the film is typically rapidly quenched to induce the desired crystallinity of the copolyester.

[0102] In particular, if the film is oriented in a sequential orientation process, the film can be further stabilized by using an in-line relaxation step. Alternatively, the relaxation process can be carried out offline. The relaxation of the film is 0% to 10%, preferably 5%. In this additional step, the film is heated at a temperature lower than that of the heat curing step, with significantly reduced MD and TD tensions. With respect to the relaxation process that controls the film speed, the reduction in film sensitivity (and therefore strain relaxation) is typically in the range of 0 to 2.5%, preferably 0.5 to 2.0%. During the thermal stabilization step, the lateral dimensions of the film do not increase. The temperature used in the thermal stabilization step may be varied depending on the desired combination of properties from the final film, with higher temperatures resulting in better properties, i.e., lower residual shrinkage characteristics. Temperatures of 135°C to 250°C are generally desirable, preferably 150°C to 230°C, and more preferably 170°C to 200°C. The duration of heating depends on the temperature used, but is typically in the range of 10 to 40 seconds, with a duration of 20 to 30 seconds being preferred. This thermal stabilization process can be carried out in a variety of ways, including horizontal and vertical configurations, and either "offline" as a separate process step or "inline" as a continuation of the film manufacturing process. Films thus processed will exhibit less thermal shrinkage than those produced without such post-heat curing relaxation.

[0103] Advantageously, the films may and preferably be manufactured in air. That is, the films are not manufactured under an atmosphere of inert gas (such as nitrogen or noble gases like argon) (including the steps of extrusion, casting, and stretching). Accordingly, the copolyester compositions and copolyester films described herein are remarkably thermally stable and do not require special operating conditions (in particular, an inert atmosphere) during manufacturing or storage.

[0104] Copolyester films can be formed by conventional solvent casting methods well known in the art, instead of by melt extrusion. Generally speaking, this process involves forming a film from a dispersion containing a copolyester, a first metal ion-containing component, an optional second metal ion-containing component, and a solvent. Suitable solvents include N-methyl-2-pyrrolidone (NMP), acetonitrile (ACN), tetrahydrofuran (THF), dimethylformamide (DMF), dimethyl sulfoxide (DMSO), dimethyl carbonate (DMC), ethylene carbonate (EC), propylene carbonate (PC), dimethoxyethane (DME), methyl formate (MF), nitromethane (NM), diethylene carbonate (DEC), toluene, water, ethanol, acetone, isopropyl alcohol, methanol, ethyl alcohol, and ethyl acetate.

[0105] The type of mixing vessel, the duration of the dispersion step, and the temperature of the dispersion step will vary depending on the type of copolyester and solvent used. The temperature used is typically between approximately 22°C and 100°C. The duration of the dispersion step will typically be several hours, for example, approximately 6 to 48 hours, 10 to 30 hours, or 12 to 24 hours.

[0106] The first metal ion-containing component and any second metal ion-containing component may already be present in the copolyester that comes into contact with the solvent to form a dispersion. Alternatively, the first and second metal ion-containing components may be mixed with the copolyester dispersion, and in this embodiment, the first and second metal ion-containing components may be introduced into the dispersion independently or together. If introduced independently, the first and second metal ion-containing components may be introduced simultaneously or sequentially. If one or both of the first and second metal ion-containing components contain multiple different compounds, the multiple compounds may be introduced independently or together, and if introduced independently, they may be introduced simultaneously or sequentially.

[0107] Next, the dispersion is cast onto a film on a support base. The cast film is then properly dried to remove any residual solvent. The cast film is typically dried at a temperature of about 50°C to about 170°C, preferably about 80°C to 160°C. It will be understood that the drying step may include multiple (e.g., at least two) drying steps across different temperature ranges to reduce the amount of residual solvent. Once dried, the cast copolyester film can be removed from the support base for subsequent processing, such as being incorporated into a battery as a separator.

[0108] If necessary, the film produced by solvent casting may undergo orientation and dimensional stabilization as described above.

[0109] In other methods of film production, the film-forming copolyester composition is cast itself onto a support base, which is a component of a battery, particularly an electrode; that is, the cast film is formed in situ during battery production. This production method is particularly useful in solvent casting, but is not limited to, and can also be used in extrusion film formation. Therefore, in this embodiment, the battery separator is formed in situ by casting a copolyester film onto the electrode during battery production. In this case, the composite structure of the electrode and the cast copolyester film undergoes subsequent processing for battery production.

[0110] It will be understood that the priorities and elements described in relation to the first aspect apply equally to the second aspect.

[0111] The present invention further provides a film manufactured by a method according to a second embodiment.

[0112] According to a third aspect, a metal-ion battery (particularly a lithium-ion battery) comprising a copolyester film as described herein is provided, comprising an anode, a cathode, and a separator between the anode and the cathode, wherein the separator is the copolyester film as described herein.

[0113] During battery use and operation, metal ions present in the copolyester film are easily mobile, allowing the separator to exhibit the necessary ionic conductivity between electrodes.

[0114] Preferably, the metal-ion battery is a solid-state battery (also referred to herein as a dry cell). Alternatively, the metal-ion battery further comprises a liquid or gel electrolyte and is typically referred to in the art as a wet cell battery. It will be understood by those skilled in the art that the metal-ion battery is a rechargeable battery.

[0115] Preferably, the metal-ion battery further includes an anode current collector and a cathode current collector.

[0116] Any suitable anode, anode current collector, cathode, and cathode current collector commonly used in the art may be used.

[0117] Suitable anodes include graphite and / or lithium titanate (LTO).

[0118] Suitable cathodes include lithium, or mixed oxides of lithium and other metals, particularly lithium titanate (LTO), lithium iron phosphate (LiFePO4, also known as LFP), and / or lithium-nickel-manganese-cobalt oxide (LiNiMnCoO2, also known as NMC).

[0119] Suitable anode and / or cathode current collectors are disclosed, for example, in UK Patent Application No. 2106834.1, the disclosures of which are incorporated herein by reference. In particular, the anode and / or cathode current collectors may be independently selected from current collectors comprising a biaxially oriented polymer substrate layer (preferably the polymer substrate layer is polyester, preferably PET or PEN) and a first metal layer on the polymer substrate layer side, wherein the polymer substrate layer has positive thermal expansion in the transverse (TD) and longitudinal (MD) directions, respectively, at 200°C in air (preferably more than 0% to 3.0%, preferably 0.1% to 2.0%, preferably 0.2%). The polymer substrate layer exhibits a viscosity of %~1.5%, and the polymer substrate layer has a thickness of 12 μm or less (preferably 1.0~12.0 μm, preferably 2.0~8.0 μm, preferably 4.0~8.0 μm, preferably 4.0~6.0 μm). The first metal layer has a thickness of 1000 nm or less. Preferably, the current collector further includes a second metal layer, the first and second metal layers are arranged on opposite sides of the polymer substrate layer, and the second metal layer independently has a thickness of 1000 nm or less. Preferably, the thickness of the first metal layer and the second metal layer, if present, are independently 50 nm~1000 nm, preferably 100 nm~1000 nm, preferably 100 nm~800 nm, and preferably 150 nm~700 nm. The first metal layer, and the second metal layer if present, preferably each independently exhibit an isotropic thermal expansion of more than 0% to 1.0%, preferably 0.25% to 0.75%, and preferably 0.3% to 0.5% at 200°C in air, and preferably the first and second metal layers exhibit the same thermal expansion at 200°C. The first metal layer, and the second metal layer if present, each independently comprises at least one of aluminum, copper, nickel, titanium, silver, nickel-copper alloy, or aluminum-zirconium alloy, and preferably the first and second metal layers are selected from the same material, and preferably both the first and second metal layers are either aluminum or copper. Such a current collector preferably exhibits one or more of the following characteristics. (i) Adhesion strength between the metal layer and the polymer substrate layer of at least 600 g / 25 mm, preferably at least about 700 g / 25 mm, preferably at least about 800 g / 25 mm. (ii) 0.01Ω sq -1 ~2.0Ωsq -1 Preferably 0.02Ωsq -1 ~2.5Ω sq -1 Preferably 0.02Ωsq -1 ~2.0Ωsq -1 Preferably 0.02Ωsq -1 ~1.5Ω sq -1 Preferably 0.05Ωsq -1 ~1.0Ωsq -1 The sheet resistance. (iii) Breakdown current of approximately 30A or less and / or breakdown temperature of approximately 300°C or less.

[0120] Such a preferred current collector can be manufactured by a method comprising (I) forming a biaxially oriented polymer substrate layer and (II) depositing a metal layer on one or both sides of the substrate layer (preferably by thermal deposition, electron beam deposition, or virtual cathode deposition). Step (I) is (1) Extruding a molten polymer layer and biaxially stretching the extruded material at a temperature exceeding the glass transition temperature(s) of the polymer, preferably by simultaneous biaxial stretching, and preferably by stretching such that the dimensions of the orientation film are 2 to 5 times the original dimensions in each stretching direction; (2) The melting temperature (T) is higher than the glass transition temperature (multiple temperatures are possible) of the polymer. M Dimensional stabilization of a biaxially oriented film by annealing it under a dimensional support at a temperature lower than ), preferably the annealing temperature being T M -80℃~T M A step in which the temperature range is -10°C, preferably in the range of 200°C to 245°C, preferably in the range of 220°C to 240°C; (3) A step in which the annealed biaxially oriented film is subjected to dimensional relaxation, preferably simultaneous dimensional relaxation in both the transverse and longitudinal directions, wherein the degree of relaxation is 0.5 to 5.0%, preferably 1.0 to 4.0%, preferably 1.0 to 3.0%, and preferably 1.0 to 2.0% in both the transverse and longitudinal directions, preferably the degree of relaxation is the same in both directions, and preferably the temperature of the relaxation step is less than or equal to the temperature of the preceding annealing step, preferably 200°C to 240°C, preferably 210°C to 230°C, and preferably 215°C to 230°C; (4) A second relaxation step, optionally performed at a temperature lower than that of the preceding relaxation step, preferably at least 5°C lower, preferably in the range of 195°C to 230°C, and preferably in the range of 195°C to 220°C; and (5) Optionally, the exposed surface of the polymer substrate layer is subjected to a surface modification treatment, the treatment step being performed after step (I) and before step (II), and preferably the treatment sequentially includes steps of applying plasma treatment, preferably corona discharge, to the exposed surface of the polymer substrate layer.

[0121] The term “metal” in the metal layer of a preferred current collector will be understood to be used in a manner separate and independent from the use of the term “metal” in relation to separators and batteries in the remainder of this disclosure. In particular, the inherent properties of the metal layer of the current collector are independent of the inherent properties of the metal ions in the separator and the inherent properties of the metal-ion battery (i.e., whether the metal-ion battery is a lithium-ion battery or a sodium-ion battery).

[0122] The priorities and elements described in relation to the first and second embodiments also apply to the third embodiment.

[0123] According to a fourth aspect, the use of the copolyester film described herein as a separator in a battery, preferably a metal-ion battery, preferably a lithium-ion battery, is provided.

[0124] The priorities and elements described in relation to the first to third aspects also apply to the fourth aspect.

[0125] According to a fifth aspect of the present invention, a method for producing a metal-ion battery comprising the copolyester film described herein, (a) the step of providing the copolyester film described herein; and (b) A method is provided comprising the step of assembling a metal-ion battery, wherein the battery comprises an anode, a cathode, and a separator between the anode and the cathode, the separator being a copolyester film obtained in step (a).

[0126] The priorities and elements described in the first to fourth aspects apply similarly to the fifth aspect.

[0127] Characteristic measurement The following test methods were used to characterize the properties of the copolyester films, separators, and batteries described herein. (i) Glass transition temperature (T g ), crystal temperature (T c ), crystal melting point (T m) These thermal parameters were measured by differential scanning calorimetry (DSC) using a PerkinElmer HyperDSC 8500. Unless otherwise specified, measurements were performed according to the standard test method described below, based on the method described in ASTM E1356-98. The sample was maintained under a dry nitrogen atmosphere for the duration of the scan. 20 ml -1 The flow rate and aluminum dish were used. The sample (5 mg) was first heated at 20°C to erase any previous thermal history. -1 The sample was then heated from 20°C to 350°C (first heating scan). After maintaining a constant temperature of 350°C for 2 minutes, the sample was then subjected to a 20°C interval. -1 Then, it was cooled to 20°C (first cooling scan). After that, the sample was cooled to 20°C. -1 Then, it was reheated to 350°C (second heating scan). g and T MThe value was obtained from the second heating scan. As is well known, the glass transition temperature of a polymer is the temperature at which it changes from a brittle, glassy state to a plastic, rubbery state. g The value was determined as the estimated onset temperature of the glass transition observed by DSC scanning (heat flow (W / g) against temperature (°C)), as described in ASTM E1356-98. The copolyester of the present invention has two T g It may be accompanied by a value, one of which is the T in the soft segment. g The other side is the hard segment T g It will be understood that this is the case. c and T m The value was determined from DSC scanning as the peak exothermic or endothermic of the transition. (ii) Melt viscosity As used herein, the term "melt viscosity" refers to the complex viscosity of a polymer measured at a specific melting temperature and oscillation frequency. Complex viscosity was measured by rotational rheology testing using TA Instruments DHR-1 according to the following test method: A polymer sample (2.5 g) was dried at 140°C for 16 hours under dynamic vacuum. The sample was then held between 2 × 25 mm diameter parallel plates and heated to the required temperature under a nitrogen atmosphere. The complex viscosity of the polymer was analyzed by temperature gradient analysis, thereby comparing the sample by 4°C. -1 Speed, constant distortion (5%), and angular frequency (10 rads) -1 It was heated in ). (iii) Transfilm ion conductivity (dry cell (solid state) setting) In a dry cell (solid state) setting, where no additional electrolyte is present, the through-film ionic conductivity of the film sample was determined by electrochemical impedance spectroscopy (EIS). A 12 mm diameter dry coin cell was constructed. A symmetric Al / Al dry coin cell with a 1 × 1 mm spacer was constructed in an argon glove box at a dew point of less than 40°C. AC impedance spectra were acquired using an AutoLab unit after applying a perturbation voltage of 10 mV, under open-circuit voltage (OCV) in the AC frequency range of 100 mHz to 1 MHz at the battery operating temperature (approximately 25°C to 75°C and ambient temperature (25°C) unless otherwise specified). A Nyquist impedance plot was generated, and the resistance R1 (in ohms) of the coin cell component and the resistance value (in ohms) of the separator relative to the bulk resistance R2 were calculated using the x-axis intercept (it can be seen that the resistance value of the separator is relatively high among the two values ​​generated from the Nyquist plot). The through-film ionic conductivity (σ) of the film separator was calculated from the bulk resistance R2 using the following formula.

number

[0128] The present invention is further described with reference to the following non-limiting embodiments. [Examples]

[0129] In the following explanation, "LICGC" refers to the lithium-ion conductive glass ceramic powder sold by Ohara under the trade name LICGC(trademark)PW-01, and "PEG3350" refers to the number average molecular weight (M) of 3350. NThis refers to polyethylene glycol containing ).

[0130] Experiment 1 A copolyester (P1) was prepared using ethylene glycol, terephthalic acid, and polyethylene glycol (PEG3350). PEG3350 was present at a level of 16.4% by weight of the copolyester.

[0131] 5551 g of terephthalic acid, 2664 g of ethylene glycol, and 2006 g of PEG3350 were reacted under pressure (approximately 40 psi) and at high temperature (approximately 255°C) with the addition of an antioxidant (Irganox® 1010, 7 g) to produce a copolyester. A small amount of sodium hydroxide (0.35 g) was added to prevent the formation of unwanted by-products, and the esterification reaction proceeded without the need for a catalyst. Water was removed from the reactants by distillation, and the reaction was stopped when 90% of the theoretical weight of water had been collected from the reactants. Next, an antifoaming agent (Xiameter® DC 1510-US, 0.35 g) was added to minimize material carryover. Then, polycondensation was carried out at approximately 275°C using a titanium-based catalyst system (Tyzor® TnBT, 2 g, and Tyzor® AC422, 7.1 g). At this time, the pressure on the molten material was reduced to less than 1 mmHg. As the polycondensation reaction progressed, the viscosity of the batch increased, and when it reached a suitable viscosity (preferably about 50 to about 100 Pa·s), the polymerization reaction was stopped by returning the pressure in the container to atmospheric pressure. The copolyester was then extruded like lace, placed in a water bath, and dried to form pellets.

[0132] A series of copolyester films were created based on copolyester P1 and containing various additives as shown in Table 1 (Table 1 also shows the final film thickness, ionic conductivity, internal resistance (R1), and bulk resistance (R2)).

[0133] A film was prepared by melt-extruding and casting copolyester P1 to form a cast copolyester film, which was then biaxially stretched using a simultaneous stretching ratio of 3.5 in the forward and transverse directions.

[0134] The film of Comparative Example 2 was dissolved / dispersed in N-methyl-2-pyrrolidone (NMP), and then Comparative Example 3 and Example 1 were prepared by solvent casting. Specifically, the components shown in Table 1 were dispersed in 5 mL of NMP and thoroughly mixed in an autoclave at 160°C for 24 hours. The resulting copolyester composition was then cast onto the surface of an aluminum disc (i.e., an electrode in a test cell) and heated at 60°C for 24 hours to dry. The dried copolyester was then vacuum-dried at 60°C for 24 hours to obtain a copolyester film.

[0135] Further comparative films including LICGC (Comparative Example 1) I obtained this product from Ohara under the product name LICGC(trademark)AG-01.

[0136] [Table 1] A comparison of Example 1 with Comparative Examples 2 and 3 demonstrates that the addition of ceramic particle material significantly improves the ionic conductivity of the polyester film. In fact, the film of Example 1 provides ionic conductivity equivalent to that of the ceramic separator in Comparative Example 1, and also has the advantage of being significantly thinner. Furthermore, the film of Example 1 exhibited advantageous flexibility compared to Comparative Example 1, which was difficult to manufacture due to its extreme brittleness and prone to breakage during use. Therefore, the film of Example 1 demonstrated an advantageous combination of ionic conductivity, flexibility, and thinness for use as a separator in solid-state batteries while maintaining ease of manufacture.

[0137] Experiment 2 The copolyester was prepared using bis(2-hydroxyethyl) isophthalate (BHEI) and polyethylene glycol (PEG3350). PEG3350 was present at a level of 50% by weight of the copolyester. The copolyester was prepared by reacting 49.82 g of BHEI and 50.18 kg of PEG3350 with the addition of an antioxidant (Irganox® 1010, 2.95 g). Polycondensation was carried out at approximately 280°C to 290°C using an antimony trioxide catalyst (0.20 g). During this time, the pressure on the molten material was reduced to less than 5 mmHg. As the polycondensation reaction progressed, the viscosity of the batch increased, and once the desired viscosity was reached, the polymerization reaction was stopped by returning the pressure in the container to atmospheric pressure. The copolyester was then extruded like lace, placed in a water bath, and dried.

[0138] Next, a series of solvent-cast copolyester films (Comparative Examples 4, 5, and Example 2) containing various additives as shown in Table 2 were prepared using copolyester P2. The copolyester was dissolved in NMP, and the other components shown in Table 2 were introduced and dispersed in a beaker and thoroughly mixed with NMP at 25°C for 12 hours. 10 mL of NMP was used in Comparative Example 4, 0.5 mL of NMP in Comparative Example 5, and 5 mL of NMP in Example 2. Films were prepared by solvent casting the obtained copolyester compositions onto an aluminum surface, drying by heating at 60°C for 24 hours, and then vacuum drying at 60°C for a further 24 hours to obtain copolyester films. Table 2 shows the thickness, ionic conductivity, internal resistance (R1), and bulk resistance (R2) of the final films.

[0139] [Table 2] A comparison of Example 2 with Comparative Examples 4 and 5 demonstrates that the addition of ceramic particle material significantly improves the ionic conductivity of the polyester film. The separator of Example 2 provides ionic conductivity close to that of the ceramic separator of Comparative Example 1, and further has the advantages of being significantly thinner and exhibiting advantageous mechanical properties, particularly flexibility without brittleness.

[0140] Experiment 3 Furthermore, the ionic conductivity of the films of Comparative Examples 3 and 5, and Examples 1 and 2, was measured at 40°C and 60°C, and the results, along with the ionic conductivity at 25°C, are shown in Table 3.

[0141] [Table 3] The results in Table 3 demonstrate that the addition of ceramic particle material significantly improves the ionic conductivity of the polyester film at all tested temperatures, reaching a commercially viable level. Furthermore, the results in Table 3 demonstrate that ionic conductivity can be reliably increased even at high temperatures. This disclosure includes the following embodiments. <Embodiment 1> A copolyester film comprising a copolyester containing repeating units derived from diols, dicarboxylic acids, and poly(alkylene oxide), further comprising a first metal ion-containing component selected from a conductive ceramic particle material, and further comprising additional metal ions from one or more sources other than the conductive ceramic particle material. <Embodiment 2> The film according to Embodiment 1, wherein the film has a thickness of 200 μm or less, preferably 150 μm or less, preferably 100 μm or less, preferably 85 μm or less, preferably 70 μm or less, preferably 50 μm or less, and preferably 35 μm or less. <Embodiment 3> The film is the film according to either Embodiment 1 or 2, having a thickness of 5 μm or more, preferably 10 μm or more, preferably 15 μm or more, and preferably 20 μm or more. <Embodiment 4> The film according to any one of Embodiments 1 to 3, wherein the copolyester comprises semicrystalline segments derived from dicarboxylic acids and aliphatic diols, and amorphous segments derived from poly(alkylene oxide). <Embodiment 5> The film according to any one of Embodiments 1 to 4, wherein the poly(alkylene oxide) constitutes 0.1 to 80% by weight, preferably about 5 to about 78% by weight, preferably about 10 to about 75% by weight, preferably about 12 to about 65% by weight, preferably about 15 to about 60% by weight, and preferably about 16 to about 55% by weight of the total weight of the copolyester. <Embodiment 6> The aforementioned diol is C 2 、C 3 , or C 4 A film according to any one of Embodiments 1 to 5, wherein the film is selected from aliphatic diols, and preferably the aliphatic diol is ethylene glycol. <Embodiment 7> The film according to any one of embodiments 1 to 6, wherein the dicarboxylic acid is an aromatic dicarboxylic acid selected from isophthalic acid, naphthalenedicarboxylic acid, and terephthalic acid. <Embodiment 8> The aforementioned poly(alkylene oxide) glycol is C 2 -C 15 Preferably C 2 -C 10 Preferably C 2 -C 6 The film according to any one of Embodiments 1 to 7, wherein the alkylene chain is preferably selected from polyethylene glycol (PEG), polypropylene glycol (PPG), and poly(tetramethylene oxide) glycol (PTMO), preferably PEG and PPG, and preferably the poly(alkylene oxide) is PEG. <Embodiment 9> The film according to any one of Embodiments 1 to 8, wherein the number-average molecular weight of the poly(alkylene oxide) is about 200 to about 20,000 g / mol, preferably about 400 to about 3,500 g / mol, and preferably about 500 to about 3,500 g / mol. <Embodiment 10> The film is the film according to any one of embodiments 1 to 9, comprising the first metal ion-containing component and the additional metal ions. <Embodiment 11> The film according to any one of embodiments 1 to 10, wherein the additional metal ion is preferably in the form of a second metal ion component selected from metal salts. <Embodiment 12> The film according to any one of embodiments 1 to 11, wherein the metal of the first metal ion-containing component is the same as the metal of the additional metal ion. <Embodiment 13> The film according to any one of Embodiments 1 to 12, wherein the metal is selected from lithium, sodium, potassium, calcium, magnesium, and aluminum, preferably selected from lithium, sodium, magnesium, and aluminum, preferably selected from lithium and sodium, and preferably lithium. <Embodiment 14> The metal is lithium, and the lithium ion-containing conductive ceramic particle material is selected from NASICON-type ceramic particle materials such as lithium ion-containing conductive glass ceramic particle material; LISICON-type ceramic particle material; perovskite-type oxide ceramic particle material; garnet-type oxide ceramic particle material; lithium phosphorus oxynitride (LIPON)-type ceramic particle material; and lithium aluminum silicate (LAS) ceramic particle material, as described in any of Embodiments 1 to 13. <Embodiment 15> The aforementioned metal is lithium, and the lithium ion-containing conductive ceramic particle material is General formula LiM y (PO 4 ) 3 NASICON-type material having (wherein M represents one or more polyvalent metal ions from, for example, Al, Si, Ti, Zr, Ge, Sn, and Hf); General formula Li 1+x M x Ti 2-x (PO 4 ) 3 NASICON-type material having (LATP) (wherein M represents a trivalent cation selected from one or more of Al, Sc, Y, and La); General formula Li 1+x Al x Ge 2-x (PO 4 ) 3 NASICON-type material having (LAGP); Li 1+x+y Al x Ti 2-x Si y P 3-y O 12 The crystalline phase and Li 2 O-Al 2 O 3 -SiO 2 -P 2 O 5 -TiO 2 A material having the following composition; Li 1+x+y Al x (Ti,Ge) 2-x Si y P 3-y O 12 The main crystal phase and Li 2 O-Al 2 O 3 -SiO 2 -P 2 O 5 -TiO 2 -GeO 2 A material having the following composition; General formula Li 2+2x Zn 1-x GeO 4 LISICON type material having (optionally, Li 2+2x Zn 1-x Ge 4 O 16 Li 14 ZnGe 4 O 16 Li (3+x) Ge x V (1-x) O 4 Li (4-x) Si (1-x) P x O 4 Other elements (typically equivalent elements) that can replace Li, Zn, and / or Ge; Li (4-x) Ge (1-x) P x S 4 Li 10 GeP 2 S 12 Thiolisicon-type materials such as; Li 3x La (2 / 3)-x TiO 3 (LLTO), Li 3x La 1 / 3-x TaO 3 Perovskite-type oxide materials such as; Li 5 La 3 M 2 O 12 (In the formula, M represents Nb and / or Ta), Li 6 ALa 2 M 2 O 12 (In the formula, A represents Ca, Sr, and / or Ba, and M represents Nb or Ta), or Li 6.5 La 2.5 Ba 0.5 ZrTaO 12 For example, the general formula Li 7-3y-x La 3 Zr 2-x M1 y M2 x O 12 Garnet-type oxide material having (wherein M1 represents a trivalent cation such as Al and Ga, M2 represents a pentavalent cation such as Nb and Ta, and x≧0 and y≦2); Li 2 PO 2 N, etc., general formula Li x PO y N z LIPON-type material having; and AlLiO 6 Si 2 A film according to any one of embodiments 1 to 14, selected from LAS-type materials such as the above. <Embodiment 16> The aforementioned metal is sodium, and the sodium ion-containing conductive ceramic particle material is a conductive glass ceramic particle material, beta-alumina and beta''-alumina phase Na 2 OnAl 2 O 3 (wherein the formula 5≦n≦11), rare earth sodium silicate, and NASICON-type materials such as sodium ion conductive oxyhalide glass; preferably, the general formula Na 3 Zr 2 Si 2 PO 12 NaTi 2 (PO 4 ) 3 NaGe 2 (PO 4 ) 3 , or Na 1+x [Sn x Ge 2-x (PO 4 ) 3 ] NASICON structure oxide having the general formula Na 5 MSi 4 O 12 Rare earth sodium silicate having (wherein M is Y, Sc, Lu, and / or any trivalent rare earth cation), and NaI-NaCl-Na2 OB 2 O 3 A film according to any of embodiments 1 to 14, selected from sodium ion conductive oxyhalide glasses such as the above. <Embodiment 17> The amount of the metal ion-containing conductive ceramic particle material present in the copolyester film is 0.1% to 60% by weight, preferably 5% to 50% by weight, preferably 8% to 35% by weight, and preferably 10% to 20% by weight, of the total weight of the copolyester film, as described in any of Embodiments 1 to 16. <Embodiment 18> The aforementioned additional metal ions are (i) Aromatic carboxylic acids, preferably aromatic dicarboxylic acids, preferably terephthalic acid or isophthalic acid; (ii) an aliphatic carboxylic acid including an aliphatic dicarboxylic acid, preferably acetic acid, glycolic acid, or succinic acid; (iii) Carbonated water; (iv) Phenolic acid, preferably salicylic acid; (v) Perchloric acid or phosphoric acid, especially mineral acids such as phosphoric acid; and (vi) The film according to any one of Embodiments 1 to 17, in the form of a metal salt selected from boric acid, preferably a salt composed of bis(oxalic acid)boric acid. <Embodiment 19> The film according to any one of Embodiments 1 to 18, wherein the additional metal ion is in the form of a metal salt of an organic acid, preferably a salt of the aromatic dicarboxylic acid from which the copolyester is derived. <Embodiment 20> The additional metal ion is in the form of a metal salt selected from the acid, preferably the carboxylic acid, preferably the dicarboxylic acid, preferably the aromatic dicarboxylic acid, preferably the alkoxylate ester of terephthalic acid, wherein the alkoxylate ester is preferably the aliphatic diol, preferably C 2-10 Aliphatic diols, preferably C 2-6 Aliphatic diols, preferably C 2 、C 3 , or C 4 The film according to Embodiment 18 or 19, which is in the form of an aliphatic diol, more preferably ethylene glycol, 1,3-propanediol, and a metal salt derived from 1,4-butanediol, more preferably ethylene glycol. <Embodiment 21> The aforementioned additional metal ions are lithium ions, specifically bis(trifluoromethanesulfonyl)imide lithium (LiTFSI) and hexafluorophosphate lithium (LiPF). 6 ), lithium tetrafluoroborate (LiBF 4 ), lithium thiocyanate (LiSCN), lithium hexafluoroarsenate (LiAsF 6 ), Lithium trifluoromethanesulfonate (LiCF 3 SO 3 ), lithium bromide (LiBr), lithium iodide (LiI), bis(trifluoromethanesulfonimide) lithium (LiN(CF) 3 SO 2 ) 2 ), Tris(trifluoromethylsulfonyl)methidolithium (LiC(CF) 3 SO 2 ) 3 ), lithium orthosilicate, lithium trifluoroacetate (LiCF 3 CO 2 ), and bis(fluorosulfite)amide lithium (LiN(FO 2 S) 2 A film according to any one of Embodiments 1 to 20, in the form of a lithium salt selected from dilithium terephthalate (DLTA), dilithium isophthalate, lithium glycolate, lithium benzoate, lithium acetate, lithium carbonate, lithium perchlorate, lithium orthosilicate, lithium phosphate, lithium salicylate, lithium succinate, lithium bis(oxalato)borate, and dilithium bishydroxyethyl terephthalate (DL-BHET). <Embodiment 22> The aforementioned additional metal ions are lithium ions, including dilithium terephthalate (DLTA), dilithium isophthalate, dilithium bishydroxyethyl terephthalate (DL-BHET), and LiCF 3 SO 3 A film according to any one of embodiments 1 to 21, which is a form of lithium salt selected from the above. <Embodiment 23> The aforementioned additional metal salt is sodium ions, and sodium nitrate (NaNO₂) 3 ), sodium perchlorate (NaClO 4 ), sodium tetrafluoroborate (NaBF 4 ), sodium hexafluorophosphate (NaPF 6 ), bis(trifluoromethanesulfonyl)imide sodium (NaTFSI), bis(trifluoromethane)sulfonimide sodium (Na[N(CF 3 SO 2 ) 2 ]), sodium hexafluoroarsenate (V) (NaAsF 6 The film according to any one of Embodiments 1 to 19, in the form of a sodium salt selected from ), sodium bis(oxalatoborate) ("NaBOB"), sodium halide (NaX) (wherein X is Cl, Br, or I), sodium thiocyanate (NaSCN), sodium pentacyanopropenide (NaPCPI), sodium tetracyanopyrrolate (NaTCP), and sodium tricyanoimidazolate (NaTIM). <Embodiment 24> The film according to any one of embodiments 1 to 23, wherein the additional metal ions are present in and retained in the polymer matrix of the film by interactions between the metal cations and the negatively charged oxygen atoms of the copolyester, preferably with at least the oxygen atoms of the polyalkylene oxide units. <Embodiment 25> The film according to any one of embodiments 1 to 23, wherein the additional metal ions are in the form of a metal salt and are retained within the polymer matrix of the film by an interaction between the metal cation and the anion of the metal salt that is not covalently bonded to the copolyester. <Embodiment 26> The amount of the additional metal ions in the film is effective in providing a metal:O molar ratio of 5:1 to 1:50, preferably about 4:1 to about 1:50, preferably about 3:1 to about 1:50, preferably about 2:1 to about 1:50, preferably about 1:1 to about 1:40, preferably about 1:2 to about 1:30, preferably about 1:4 to about 1:25, the film according to any one of Embodiments 1 to 25, wherein the number of O atoms in the ratio is defined as the number of O atoms in the poly(alkylene oxide) residue, and the number of metal atoms in the ratio is defined as the number of metal atoms provided by the additional metal ions. <Embodiment 27> The film according to any one of Embodiments 1 to 26, wherein the additional metal ions are in the form of a second metal ion component (preferably a metal salt) present in an amount of 0.1% to 40% by weight, preferably 1% to 10% by weight, of the total weight of the copolyester film. <Embodiment 28> The film according to any one of Embodiments 1 to 27, wherein the copolyester, the first metal ion-containing component, and, if present, the second metal ion component containing the additional metal ions, are the main components of the film, preferably constituting at least about 85%, preferably at least about 95% by weight, and preferably at least about 98% by weight, of the total weight of the copolyester film. <Embodiment 29> A film according to any one of embodiments 1 to 28, further comprising an antioxidant. <Embodiment 30> A film according to any one of embodiments 1 to 29, further comprising an inorganic particle filler selected from metalloids such as alumina, titania, zirconia, zinc oxide, talc, and silica; calcined clay; alkali metal salts such as calcium and barium carbonates and sulfates; and non-conductive ceramic particle materials, wherein the inorganic particle filler is a separate entity distinct from the first metal ion-containing component and the second metal ion-containing component, does not contain the metal ions of the first metal ion-containing component or the second metal ion-containing component, and the inorganic particle filler is present in an amount of 5% to 20% by weight relative to the total weight of the copolyester film. <Embodiment 31> Measured at 25℃, at least approximately 10 -7 S / cm, preferably at least about 10 -6 Conductivity in S / cm, and / or measured at 60°C, at least about 10 -6 S / cm, preferably at least about 10 -5 A film according to any one of embodiments 1 to 30, exhibiting a conductivity of S / cm. <Embodiment 32> A film according to any one of embodiments 1 to 31, which is a self-supporting biaxially oriented film. <Embodiment 33> A method for manufacturing a polyester film according to any one of Embodiments 1 to 32, (i) The diol is the dicarboxylic acid or its ester (preferably a lower alkyl (C 1-4 A step of reacting the dicarboxylic acid with an ester, preferably the dimethyl ester, to form a bis(hydroxyalkyl)-ester; (ii) A step of polymerizing the bis(hydroxyalkyl)-ester of the dicarboxylic acid by polycondensation in the presence of poly(alkylene oxide) to form a copolyester; (iii) A step of forming a copolyester composition by introducing the first metal ion-containing component selected from conductive ceramic particle material and, optionally, the additional metal ions from one or more sources other than the conductive ceramic particle material, during the synthesis of the copolyester in step (i) and / or step (ii), and / or during a subsequent separate compounding or mixing step; and (iv) The method comprising the step of forming a copolyester film from the copolyester composition, preferably by melt extrusion of the composition or by solvent casting of a dispersion or solution containing the copolyester composition. <Embodiment 34> A method for producing a polyester film according to Embodiment 33, wherein the reaction product of step (ii) is subjected to solid-phase polymerization. <Embodiment 35> The method according to embodiment 33 or 34, wherein the film itself is cast onto a support base which is a component of a solid battery, preferably an electrode. <Embodiment 36> A film obtained by the method described in any one of Embodiments 33 to 35. <Embodiment 37> A metal-ion battery comprising an anode, a cathode, and a separator between the anode and the cathode, wherein the separator is a film according to any one of embodiments 1 to 32 or 36. <Embodiment 38> The metal-ion battery according to embodiment 37, wherein the metal-ion battery is a solid-state battery. <Embodiment 39> The metal-ion battery according to Embodiment 37 or 38, wherein the metal in the metal-ion battery is selected from lithium, sodium, potassium, calcium, magnesium, and aluminum, preferably selected from lithium, sodium, magnesium, and aluminum, preferably selected from lithium and sodium, and preferably lithium. <Embodiment 40> The anode is selected from graphite and lithium titanate (LTO) anodes, and / or the cathode is lithium, or a mixed oxide of lithium and other metals, particularly lithium titanate, lithium iron phosphate (LiFePO4). 4 ), and / or lithium-nickel-manganese-cobalt oxide (LiNiMnCoO 2 A metal-ion battery according to embodiment 37, 38, or 39, made from ). <Embodiment 41> The metal-ion battery according to any one of embodiments 37 to 40, further comprising an anode current collector disposed on the surface of the anode and a cathode current collector disposed on the surface of the cathode, wherein the order of the layers is anode current collector / anode / separator / cathode / cathode current collector. <Embodiment 42> The anode current collector and / or the cathode current collector are independently selected from a current collector comprising a biaxially oriented polyester substrate layer and a first metal layer on the polyester substrate layer side, wherein the polyester substrate layer exhibits positive thermal expansion in the transverse (TD) and longitudinal (MD) directions at 200°C in air, the polyester substrate layer has a thickness of 12 μm or less, the first metal layer has a thickness of 50 to 1000 nm, and preferably the current collector further comprises a second metal layer having a thickness of 50 to 1000 nm, the first metal layer and the A metal-ion battery according to any of embodiments 37 to 41, wherein the second metal layer is disposed on opposite sides of the polyester substrate layer, preferably the first metal layer, and if present, the second metal layer independently comprises at least one of aluminum, copper, nickel, titanium, silver, nickel-copper alloy, or aluminum-zirconium alloy, and preferably the first and second metal layers are selected from the same material, and preferably both the first and second metal layers are aluminum or copper. <Embodiment 43> The use of a film as a separator in a metal-ion battery, as defined in any of embodiments 1 to 32 or 36, wherein the battery is as defined in any of embodiments 37 to 42. <Embodiment 44> A method for manufacturing a metal-ion battery as defined in any of embodiments 37 to 42, comprising a copolyester film as defined in any of embodiments 1 to 32 or 36, (a) the step of providing a copolyester film as defined in any of embodiments 1 to 32 or 36; and (b) A step of assembling the metal-ion battery, wherein the battery comprises an anode, a cathode, and a separator between the anode and the cathode, and the separator is the copolyester film obtained in step (a), The method comprising the above.

Claims

1. A copolyester film comprising a copolyester containing repeating units derived from diols, dicarboxylic acids, and poly(alkylene oxide), further comprising a first metal ion-containing component selected from a conductive ceramic particle material, wherein the first metal ion-containing component is a lithium ion-containing component or a sodium ion-containing component, and further comprising additional metal ions from one or more sources other than the conductive ceramic particle material, wherein the metal of the additional metal ions is the same as the metal of the first metal ion-containing component. When the first metal ion-containing component is a lithium ion-containing component, the lithium ion-containing conductive ceramic particle material is selected from NASICON-type ceramic particle material; LISICON-type ceramic particle material; perovskite-type oxide ceramic particle material; garnet-type oxide ceramic particle material; lithium phosphate oxynitride (LIPON)-type ceramic particle material; and lithium aluminum silicate (LAS) ceramic particle material, or When the first metal ion-containing component is a sodium ion-containing component, the sodium ion-containing conductive ceramic particle material is a NASICON-type material; beta-alumina and beta''-alumina phase Na 2 O・nAl 2 O 3 (wherein the formula 5 ≤ n ≤ 11); selected from rare earth sodium silicate; and sodium ion conductive oxyhalide glass, (i) a biaxially oriented film that exists independently, and / or (ii) the amount of copolyester present in the copolyester film is at least 40% of the total weight of the copolyester film.

2. The film is the film according to claim 1, wherein the film has a thickness of 200 μm or less.

3. The film is the film according to claim 1, wherein the film has a thickness of 5 μm or more.

4. The film according to claim 1, wherein the copolyester comprises semicrystalline segments derived from dicarboxylic acids and aliphatic diols, and amorphous segments derived from poly(alkylene oxide).

5. The film according to claim 1, wherein the poly(alkylene oxide) constitutes 0.1 to 80% by weight of the total weight of the copolyester.

6. The aforementioned diol is C 2 , C 3 , or C 4 A film according to claim 1, selected from aliphatic diols.

7. The film according to claim 1, wherein the dicarboxylic acid is an aromatic dicarboxylic acid selected from isophthalic acid, naphthalenedicarboxylic acid, and terephthalic acid.

8. The aforementioned poly(alkylene oxide) glycol is C 2 -C 15 The film according to claim 1, selected from alkylene chains.

9. The film according to claim 1, wherein the number-average molecular weight of the poly(alkylene oxide) is 200 to 20,000 g / mol.

10. The film according to claim 1, wherein the amount of copolyester present in the copolyester film is at least 40% of the total weight of the copolyester film.

11. The film according to claim 1, wherein the additional metal ions are in the form of a second metal ion component.

12. The film according to claim 1, wherein the metal is lithium.

13. The film according to claim 1, wherein the metal is lithium, and the lithium ion-containing conductive ceramic particle material is a NASICON-type ceramic particle material which is a lithium ion-containing conductive glass ceramic particle material.

14. The aforementioned metal is lithium, and the lithium ion-containing conductive ceramic particle material is General formula Li 1+x Al x Ge 2-x (PO 4 ) 3 NASICON-type material having (LAGP) (where x is 0.5); Li 2+2x Zn 1-x Ge 4 O 16 Li 14 ZnGe 4 O 16 Li (3+x) Ge x V (1-x) O 4 Li (4-x) Si (1-x) P x O 4 A LISICON-type material having a general formula selected from (where x is between 0 and 1); ThiolisICON type material; Li (4-x) Ge (1-x) P x S 4 Li 10 GeP 2 S 12 (In the equation, x is between 0 and 1); Perovskite-type oxide materials; General formula Li 7-3y-x La 3 Zr 2-x M1 y M2 x O 12 Garnet-type oxide material having (wherein M1 represents a trivalent cation, M2 represents a pentavalent cation, and x≧0 and y≦2); LAS type material; and AliO 6 Si 2 A film according to claim 1, selected from the following.

15. The aforementioned metal is sodium, and the sodium ion-containing conductive ceramic particle material has the general formula Na 3 Zr 2 Si 2 PO 12 NaTi 2 (PO 4 ) 3 , or NaGe 2 (PO 4 ) 3 NASICON structure oxide having the general formula Na 5 MSi 4 O 12 Rare earth sodium silicate having (wherein M is Y, Sc, Lu, and / or any trivalent rare earth cation); and NaI-NaCl-Na 2 O-B 2 O 3 The film according to claim 1, selected from sodium ion conductive oxyhalide glasses.

16. The film according to claim 1, wherein the amount of the metal ion-containing conductive ceramic particle material present in the copolyester film is 0.1% by weight to 60% by weight of the total weight of the copolyester film.

17. The aforementioned additional metal ions are (i) Aromatic carboxylic acids; (ii) Aliphatic carboxylic acids; (iii) Carbonated; (iv) Phenolic acid; (v) Mineral acids; and (vi) The film according to claim 1, wherein the form is a metal salt selected from salts composed of boric acid.

18. The film according to claim 1, wherein the additional metal ions are in the form of a metal salt of an organic acid.

19. The film according to claim 17, wherein the additional metal ion is in the form of a metal salt selected from the alkoxylate esters of the acid, and / or the alkoxylate ester is derived from the aliphatic diol.

20. The aforementioned additional metal ions are lithium ions, specifically bis(trifluoromethanesulfonyl)imide lithium (LiTFSI) and hexafluorophosphate lithium (LiPF). 6 ), lithium tetrafluoroborate (LiBF 4 ), lithium thiocyanate (LiSCN), lithium hexafluoroarsenate (LiAsF 6 ), lithium trifluoromethanesulfonate (LiCF 3 SO 3 ), lithium bromide (LiBr), lithium iodide (LiI), bis(trifluoromethanesulfonimide) lithium (LiN(CF) 3 SO 2 ) 2 ), Tris(trifluoromethylsulfonyl)methidolithium (LiC(CF 3 SO 2 ) 3 ), lithium orthosilicate, lithium trifluoroacetate (LiCF 3 CO 2 ), bis(fluorosulfite)amide lithium (LiN(FO 2 S) 2 The film according to claim 1, in the form of a lithium salt selected from ), dilithium terephthalate (DLTA), dilithium isophthalate, lithium glycolate, lithium benzoate, lithium acetate, lithium carbonate, lithium perchlorate, lithium orthosilicate, lithium phosphate, lithium salicylate, lithium succinate, lithium bis(oxalato)borate, and dilithium bishydroxyethyl terephthalate (DL-BHET).

21. The additional metal ions are lithium ions, including dilithium terephthalate (DLTA), dilithium isophthalate, dilithium bishydroxyethyl terephthalate (DL-BHET), and LiCF 3 SO 3 The film according to claim 1, which is a form of lithium salt selected from the above.

22. The aforementioned additional metal salt is a sodium ion, and sodium nitrate (NaNO₂) 3 ), sodium perchlorate (NaClO 4 ), sodium tetrafluoroborate (NaBF 4 ), sodium hexafluorophosphate (NaPF 6 ), bis(trifluoromethanesulfonyl)imide sodium (NaTFSI), bis(trifluoromethane)sulfonimide sodium (Na[N(CF 3 SO 2 ) 2 ]), sodium hexafluoroarsenate (V) (NaAsF 6 The film according to claim 1, in the form of a sodium salt selected from ), bis(oxalatoborate) sodium ("NaBOB"), sodium halide (NaX) (wherein X is Cl, Br, or I), sodium thiocyanate (NaSCN), sodium pentacyanopropenide (NaPCPI), sodium tetracyanopyrrolate (NaTCP), and sodium tricyanoimidazolate (NaTIM).

23. The film according to claim 1, wherein the additional metal ions are present in and retained in the polymer matrix of the film by interaction between the metal cations and the negatively charged oxygen atoms of the copolyester.

24. The film according to claim 1, wherein the additional metal ions are in the form of a metal salt and are retained within the polymer matrix of the film by an interaction between the metal cation and the anion of the metal salt that is not covalently bonded to the copolyester.

25. The amount of the additional metal ions in the film is effective in providing a metal:O molar ratio of 5:1 to 1:50, wherein the number of O atoms in the ratio is defined as the number of O atoms in the poly(alkylene oxide) residue, and the number of metal atoms in the ratio is defined as the number of metal atoms provided by the additional metal ions, as described in claim 1.

26. The film according to claim 1, wherein the additional metal ions are in the form of a second metal ion component (or metal salt) present in an amount of 0.1% to 40% by weight of the total weight of the copolyester film.

27. The film according to claim 1, wherein the copolyester, the first metal ion-containing component, and the second metal ion component containing the additional metal ions are the main components of the film and / or constitute at least 85% by weight of the total weight of the copolyester film.

28. The film according to claim 1, further comprising an antioxidant.

29. The film according to claim 1, further comprising an inorganic particle filler selected from metalloid oxides; fired clay; alkali metal salts or calcium and barium carbonates and sulfates; and non-conductive ceramic particle materials, wherein the inorganic particle filler is a separate entity distinct from the first metal ion-containing component and the second metal ion-containing component, does not contain the metal ions of the first metal ion-containing component or the second metal ion-containing component, and the inorganic particle filler is present in an amount of 5% to 20% by weight relative to the total weight of the copolyester film.

30. At least 10 when measured at 25°C -7 Conductivity in S / cm, and / or measured at 60°C, at least 10 -6 The film according to claim 1, exhibiting a conductivity of S / cm.

31. The film according to claim 1, which is a self-supporting biaxially oriented film.

32. A method for producing a polyester film according to any one of claims 1 to 31, (i) The step of reacting the diol with the dicarboxylic acid or its ester to form a bis(hydroxyalkyl) ester of the dicarboxylic acid; (ii) A step of polymerizing the bis(hydroxyalkyl)-ester of the dicarboxylic acid by polycondensation reaction in the presence of poly(alkylene oxide) to form a copolyester; (iii) A step of forming a copolyester composition by introducing the first metal ion-containing component selected from conductive ceramic particle material and the additional metal ions from one or more sources other than the conductive ceramic particle material during the synthesis of the copolyester in step (i) and / or step (ii), and / or during a subsequent separate compounding or mixing step; and (iv) The method comprising the step of forming a copolyester film from the copolyester composition.

33. A method for producing a polyester film according to claim 32, wherein the reaction product of step (ii) is subjected to solid-phase polymerization.

34. The method according to claim 32, wherein the film is cast onto a support base which is itself a component of a solid battery.

35. A film obtained by the method described in claim 32.

36. A metal ion battery comprising an anode, a cathode, and a separator between the anode and the cathode, wherein the separator is a film according to any one of claims 1 to 31.

37. The metal ion battery according to claim 36, wherein the metal ion battery is a solid-state battery.

38. The metal-ion battery according to claim 36, wherein the metal in the metal-ion battery is selected from lithium.

39. The metal-ion battery according to claim 36, wherein the anode is selected from graphite and lithium titanate (LTO) anodes, and / or the cathode is made from lithium or a mixed oxide of lithium and other metals.

40. The metal-ion battery according to claim 36, further comprising an anode current collector disposed on the surface of the anode and a cathode current collector disposed on the surface of the cathode, wherein the order of the layers is anode current collector / anode / separator / cathode / cathode current collector.

41. The metal-ion battery according to claim 36, wherein the anode current collector and / or the cathode current collector are independently selected from a current collector comprising a biaxially oriented polyester substrate layer and a first metal layer on the polyester substrate layer side, the polyester substrate layer exhibits positive thermal expansion in the transverse (TD) and longitudinal (MD) directions, respectively, at 200°C in air, the polyester substrate layer has a thickness of 12 μm or less, the first metal layer has a thickness of 50 to 1000 nm, and / or the current collector further comprises a second metal layer having a thickness of 50 to 1000 nm, the first metal layer and the second metal layer are arranged on opposite sides of the polyester substrate layer.

42. The metal-ion battery according to claim 41, wherein the first metal layer, and if present, the second metal layer, each independently comprises at least one of aluminum, copper, nickel, titanium, silver, nickel-copper alloy, or aluminum-zirconium alloy.

43. Use of a film as defined in any one of claims 1 to 31 as a separator in a metal ion battery.

44. A method for manufacturing a metal ion battery as defined in claim 36, comprising a copolyester film as defined in any one of claims 1 to 31, (a) the step of providing a copolyester film as defined in any one of claims 1 to 31; and (b) A step of assembling the metal-ion battery, wherein the battery includes an anode, a cathode, and a separator between the anode and the cathode, and the separator is the copolyester film obtained in step (a), The method comprising the above.

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