Patent Application
20250210704
The present invention relates to polymers for use in batteries and battery components. The invention also relates to batteries and battery components (e.g., electrolytes and cathodes) comprising the polymers, as well as to processes for preparing the polymers and battery components.
Rechargeable lithium-ion batteries (LIBs) are ubiquitous in modern technology, powering mobile phones, personal computers and an emerging field of wearable electronics. However, next-generation rechargeable batteries are critical to transforming large-scale grid-energy storage (from sustainable wind and solar sources) and the phasing out of petrol/diesel cars through the widespread commercialization of affordable and practical electric vehicles.1 New battery technologies must meet stricter safety requirements, lower production costs, and achieve enhanced performance such as higher capacities (10,000×portable electronics), faster charging (<30 mins), and higher energy densities (>250 Whkg−1).2 Polymers can play an essential role in battery devices acting as electrolytes, binders, interface modifiers, separators and packaging.
Increasingly, however, advanced functional polymer materials are required that combine conductivity, stability, adhesive and mechanical properties (elastomeric torobust plastics) and processability.3-10
To improve battery safety, replacing flammable liquid electrolytes in commercial LIBs with solid-state alternatives is widely regarded. Solid-state electrolytes can also enable use of higher-voltage cathode materials (>3.5V) to enhance battery capacities and allow5,11 the use of lithium metal anodes to attain higher energy densities. Despite significant progress in all-solid-state batteries, an outstanding challenge remains to maintain physical particle-particle contact of all the solid components (a pre-requisite for charge movement) without applying unpractical high pressures (typically 50 MPa). For example, cathode materials such as LiNixMnyCozO2 (NMC) are composed of sheets of cobalt oxide with intercalated lithium ions and undergo a volume change (as much as 10%) during battery charging/discharging as a result of (de)intercalation of Li-ions.12-13 Repeated cycling subsequently leads to loss of solid-solid contact and deterioration of battery performance.
To avoid applying unpractical pressures, the use of well-designed polymers to accommodate these volume changes is increasingly coming into focus to enable the practical realization of all-solid-state batteries (ASSBs).14,15, Polyvinylidene fluoride (PVDF) is a common polymer binder used in cathode materials due to its high chemical stability, but it lacks the elasticity to accommodate deformations.16,17 The use of elastomers such as styrenic block copolymers (SBS and SEBS) has shown promise in improving the capacity retention of LIBs with cycle number that typically diminishes due to volume changes.18 However, the low polarity of these hydrocarbon polymer backbones means they show poor attachment to the inorganic electrode materials, resulting in an unstable mechanical interface/loss of electrode integrity/failure of contacts. Computational work by Carter and coworkers19 suggests delamination of these interfaces is induced when electrode particles undergo as little as 7.5% volume charge during (de)lithiation.
To date, poly(ethylene oxide) (PEO) has been the most successful and extensively studied polymer electrolyte owing to its ability for coordinating Li-ions and solvating a variety of lithium salts with ion transport by hopping between oxygen sites being facilitated by the high chain flexibility of PEO related with its low glass transition (Tg˜-64° C.).20,21 However, the semi-crystalline nature of PEO (70-84% at room temperature) limits its room-temperature ionic conductivity (10−8-10−7 S cm−1) and mechanical properties, leading to brittle materials.
In spite of the advances made in this field, there remains a need for structurally well-defined polymeric materials having electrochemical and mechanical properties making them suitable for use in batteries and battery components.
The present invention was devised with the foregoing in mind.
According to a first aspect of the present invention there is provided a polymer having a structure according to Formula I:
A-B-A (I)
According to a second aspect of the present invention there is provided a process for the preparation of a polymer, the process comprising the steps of:
According to a third aspect of the present invention there is provided a polymer obtained, directly obtained or obtainable by the process of the second aspect.
According to a fourth aspect of the present invention there is provided an electrolyte comprising a mixture of a polymer of the first or third aspect and a metal salt.
According to a fifth aspect of the present invention there is provided a process for making an electrolyte, the process comprising the step of:
According to a sixth aspect of the present invention there is provided a cathode for a battery, the cathode comprising a polymer of the first or third aspect, and/or an electrolyte of the fourth aspect.
According to a seventh aspect of the present invention there is provided a battery comprising a polymer of the first or third aspect, an electrolyte of the fourth aspect, and/or a cathode of the sixth aspect.
According to an eighth aspect of the present invention there is provided a use of a polymer of the first or third aspect in the manufacture of a battery or a battery component.
The term “(m-nC)” or “(m-nC) group” used alone or as a prefix, refers to any group having m to n carbon atoms.
The term “alkyl” as used herein refers to straight or branched chain alkyl moieties, typically having 1, 2, 3, 4, 5 or 6 carbon atoms. This term includes reference to groups such as methyl, ethyl, propyl (n-propyl or isopropyl), butyl (n-butyl, sec-butyl or tert-butyl), pentyl, hexyl and the like. Most suitably, an alkyl may have 1, 2, 3 or 4 carbon atoms.
The term “alkylene” as used herein refers to a divalent equivalent of an alkyl group as described above.
The term “alkenyl” as used herein refers to straight or branched chain alkenyl moieties, typically having 1, 2, 3, 4, 5 or 6 carbon atoms. The term includes reference to alkenyl moieties containing 1, 2 or 3 carbon-carbon double bonds (C═C). This term includes reference to groups such as ethenyl (vinyl), propenyl (allyl), butenyl, pentenyl and hexenyl, as well as both the cis and trans isomers thereof.
The term “alkynyl” as used herein refers to straight or branched chain alkynyl moieties, typically having 1, 2, 3, 4, 5 or 6 carbon atoms. The term includes reference to alkynyl moieties containing 1, 2 or 3 carbon-carbon triple bonds (C═C). This term includes reference to groups such as ethynyl, propynyl, butynyl, pentynyl and hexynyl.
The term “alkoxy” as used herein refers to —O-alkyl, wherein alkyl is a straight or branched chain and comprises 1, 2, 3, 4, 5 or 6 carbon atoms. In one class of embodiments, alkoxy has 1, 2, 3 or 4 carbon atoms. This term includes reference to groups such as methoxy, ethoxy, propoxy, isopropoxy, butoxy, tert-butoxy, pentoxy, hexoxy and the like.
The term “aryl” or “aromatic” as used herein means an aromatic ring system comprising 6, 7, 8, 9 or 10 ring carbon atoms. Aryl is often phenyl but may be a polycyclic ring system, having two or more rings, at least one of which is aromatic. This term includes reference to groups such as phenyl, naphthyl and the like.
The term “aryl-(m-nC)alkyl” means an aryl group covalently attached to a (m-nC)alkylene group, both of which are described herein. Examples of aryl-(m-nC)alkyl groups include benzyl, phenylethyl, and the like.
The term “heteroaryl” or “heteroaromatic” means an aromatic mono-, bi-, or polycyclic ring incorporating one or more (for example 1-4, particularly 1, 2 or 3) heteroatoms selected from nitrogen, oxygen or sulfur. Examples of heteroaryl groups are monocyclic and bicyclic groups containing from five to twelve ring members, and more usually from five to ten ring members. The heteroaryl group can be, for example, a 5- or 6-membered monocyclic ring or a 9- or 10-membered bicyclic ring, for example a bicyclic structure formed from fused five and six membered rings or two fused six membered rings. Each ring may contain up to about four heteroatoms typically selected from nitrogen, sulfur and oxygen. Typically, the heteroaryl ring will contain up to 3 heteroatoms, more usually up to 2, for example a single heteroatom.
The term “heteroaryl-(m-nC)alkyl” means an heteroaryl group covalently attached to a (m-nC)alkylene group, both of which are described herein.
The term “carbocyclyl”, “carbocyclic” or “carbocycle” means a non-aromatic saturated or partially saturated monocyclic, or a fused, bridged, or spiro bicyclic carbocyclic ring system(s). Monocyclic carbocyclic rings contain from about 3 to 12 (suitably from 3 to 7) ring atoms. Bicyclic carbocycles contain from 7 to 17 carbon atoms in the rings, suitably 7 to 12 carbon atoms, in the rings. Bicyclic carbocyclic rings may be fused, spiro, or bridged ring systems.
The term “heterocyclyl”, “heterocyclic” or “heterocycle” means a non-aromatic saturated or partially saturated monocyclic, fused, bridged, or spiro bicyclic heterocyclic ring system(s). Monocyclic heterocyclic rings contain from about 3 to 12 (suitably from 3 to 7) ring atoms, with from 1 to 5 (suitably 1, 2 or 3) heteroatoms selected from nitrogen, oxygen or sulfur in the ring. Bicyclic heterocycles contain from 7 to 17 member atoms, suitably 7 to 12 member atoms, in the ring. Bicyclic heterocyclic(s) rings may be fused, spiro, or bridged ring systems.
The term “halogen” or “halo” as used herein refers to F, Cl, Br or I. In a particular, halogen may be F or Cl, of which Cl is more common.
The term “haloalkyl” is used herein to refer to an alkyl group in which one or more hydrogen atoms have been replaced by halogen (e.g. fluorine) atoms. Often, haloalkyl is fluoroalkyl. Examples of haloalkyl groups include —CH2F, —CHF2 and —CF3.
The term “substituted” as used herein in reference to a moiety means that one or more, especially up to 5. Preferably, “substituted” as used herein in reference to a moiety means that 1, 2 or 3, of the hydrogen atoms in said moiety are replaced independently of each other by the corresponding number of the described substituents. Even more preferred, “substituted” as used herein in reference to a moiety means that 1 or 2, of the hydrogen atoms in said moiety are replaced independently of each other by the corresponding number of the described substituents. The term “optionally substituted” as used herein means substituted or unsubstituted.
It will, of course, be understood that substituents are only at positions where they are chemically possible, the person skilled in the art being able to decide (either experimentally or theoretically) without inappropriate effort whether a particular substitution is possible
Throughout the entirety of the description and claims of this specification, where subject matter is described herein using the term “comprise” (or “comprises” or “comprising”), the same subject matter instead described using the term “consist of” (or “consists of” or “consisting of”) or “consist essentially of” (or “consists essentially of” or “consisting essentially of”) is also contemplated.
Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.
Features described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The invention is not restricted to the details of any of the specific embodiments recited herein. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.
Unless otherwise specified, where the quantity or concentration of a particular component of a given product is specified as a weight percentage (wt. % or % w/w), said weight percentage refers to the percentage of said component by weight relative to the total weight of the product as a whole. It will be understood by those skilled in the art that the sum of weight percentages of all components of a product will total 100 wt. %. However, where not all components are listed (e.g. where a product is said to “comprise” one or more particular components), the weight percentage balance may optionally be made up to 100 wt % by unspecified ingredients.
In a first aspect, the present invention provides a polymer having a structure according to Formula I:
A-B-A (I)
Through detailed investigations, the inventors have devised new tri-block copolymers having electrochemical and mechanical properties making them suitable for use in batteries and battery components (e.g. electrolytes and cathodes). The polymers can be straightforwardly and flexibly prepared using environmentally friendly raw materials by a ring opening copolymerisation (ROCOP) technique, which affords a high degree of control over the polymer's structure, thereby allowing the polymer's properties to be tuned according to a particular application.
Each block A may comprise n number of repeating units, wherein each n is 1 to 1000. Suitably, each n is 2 to 300.
Block B may comprises m number of repeating units, wherein m is 5-10,000. Suitably, m is 15-3000.
The tri-block copolymers of the invention are suitably block phase-separated (as opposed to block phase-miscible). Phase separation of the blocks within the copolymer may be indicated by the presence of two distinct glass transition temperatures (Tg); one for block A and one for block B.
Block A may have a glass transition temperature (Tg) that is ≥20° C. (e.g. 20-120° C.). Suitably, block A has a glass transition temperature (Tg) that is ≥60° C. More suitably, block A has a glass transition temperature (Tg) that is ≥80° C. Most suitably, block A has a glass transition temperature (Tg) that is 90-115° C.
Block B may have a glass transition temperature (Tg) that is ≤20° C. (e.g. −60 to 20° C.). Suitably, block B has a glass transition temperature (Tg) that is ≤0° C. More suitably, block B has a glass transition temperature (Tg) that is ≤−25° C. Most suitably, block B has a glass transition temperature (Tg) that is −50 to −30° C.
In embodiments, block A has a glass transition temperature (Tg) that is 90-115° C. and block B has a glass transition temperature (Tg) that is −50 to −30° C.
Block B may have a dispersity (Ð) of 51.30. Alternatively/additionally, the polymer itself may have a dispersity (Ð) of 51.30.
A proportion of the A and/or B block repeating units may independently comprise a pendant neutral functional group, FGN, and/or a pendant anionic functional group, FGA. Such functional groups can be used to tune the properties (e.g., adhesivity) of the polymer according to the desired battery application. For example, functional groups that are able to participate in hydrogen-bonding can improve the polymer's ability to withstand volume changes that occur during (de)lithiation. Exemplary pendant neutral functional groups, FGN include —P(O)(OH)2, —COOH, —OH, —SO3H, —NH2, —C(O)NH2, —F, —CF3 and —CN. Exemplary pendant anionic functional groups, FGA include —PO32−, —PO2(OH)−, —COO−, —SO3−, —SO2N−SO2CF3, —N−SO2CF3, —(CF2)2O(CF2)2SO3−, —BO4−, —(C6H4)4B−, —(C6F4)4B− and —CHFCF2SO3−. The skilled person will be familiar with chemical techniques by which such functional groups can be introduced into some or all of the repeating units forming blocks A and/or B. Suitably, a proportion (e.g., some, but not all) of the A block repeating units comprises a group FGN and/or a group FGA.
In embodiments, a proportion of the A and/or B block repeating units comprise a neutral functional group being —P(O)(OH)2. The inclusion of phosphonate groups, which can participate in hydrogen-bonding, within the polymer can improve the polymer's ability to withstand volume changes that occur during (de)lithiation.
Block A may be amorphous. Amorphous polymers have no observable melting point when analysed by differential scanning calorimetry. Suitably, blocks A and B are amorphous.
The polymer may have a molecular weight (Mn) of 2-150 kg mol−1. Suitably, the polymer has a molecular weight (Mn) of 3-80 kg mol−1. More suitably, the polymer has a molecular weight (Mn) of 10-60 kg mol−1. The molecular weight (Mn) of the polymer can be determined by 1H NMR integration.
Block B may have a molecular weight (Mn) of 0.8-150 kg mol−1. Suitably, block B has a molecular weight (Mn) of 3-110 kg mol−1. More suitably, block B has a molecular weight (Mn) of 4-60 kg mol−1. More suitably, block B has a molecular weight (Mn) of 5-45 kg mol−1. In some particular embodiments, block B has a molecular weight (Mn) of 6-12 kg mol−1. In other particular embodiments, block B has a molecular weight (Mn) of 30-40 kg mol−1. The molecular weight (Mn) of the polymer can be determined by SEC.
The polymer may comprise 10-80 wt % of block A. The wt % of block A recited herein refers to the total amount of such blocks present with the polymer. Suitably, the polymer comprises 20-75 wt % of block A. In some particular embodiments, the polymer comprises 20-40 wt % of block A. In other particular embodiment, the polymer comprises 50-75 wt % of block A. The wt % of block within the polymer can be determined by relative 1H NMR integration of block A and B signals.
In embodiments, block B has a molecular weight (Mn) of 30-40 kg mol−1 and the polymer comprises 60-80 wt % of block A. Suitably, the polymer comprises 65-75 wt % of block A.
In embodiments, block B has a molecular weight (Mn) of 30-40 kg mol−1 and the polymer comprises 20-40 wt % of block A. Suitably, the polymer comprises 22-30 wt % of block A
In embodiments, block B has a molecular weight (Mn) of 6-12 kg mol−1 and comprises 25-55 wt % of block A. Suitably, the polymer comprises 32-42 wt % of block A.
Blocks A may have a structure according to Formula A-i:
It will be understood by those of skill in the art that the use of square brackets denotes a repeating unit within the polymeric block.
Repeating units of the type depicted in Formula A-i can be prepared by ROCOP of CO2 with an epoxide (e.g., where L separates the two oxygen atoms by a distance of 2 oxygen atoms) or an oxetane (e.g., where L separates the two oxygen atoms by a distance of 3 oxygen atoms).
It will be appreciated that a variety of epoxides and oxetanes can be used to form the repeating unit in Formula A-i, some of which are described herein in relation to the second aspect of the invention.
L is suitably a linking group that separates the two oxygen atoms to which it is attached by a distance of 2 carbon atoms. The two carbon atoms may form part of a ring. The ring may be a 5- to 7-membered carbocyclyl or heterocyclyl ring. Most suitably, the ring is a 6-membered carbocyclyl ring.
It will be understood that the end group Xa can take a variety of forms. Often, Xa is H.
Block A may have a structure according to Formula A-ii:
Repeating units of the type depicted in Formula A-ii can be prepared by ROCOP of CO2 with a cyclohexene oxide. Since a variety of substituted epoxides of this type are readily available, or can be straightforwardly prepared by known chemistries, it will be appreciated that R1, when present, can take a variety of forms.
When v is 0, X is a terminal group. For example, X may be a vinyl group that was present on the cyclohexyl ring during polymerisation. Alternatively, X can be a linking group (when v is 1) that connects the cyclohexyl ring to one of the aforementioned functional groups. Continuing with the example of a vinyl group present on the cyclohexyl ring during polymerisation, some of these vinyl groups can, following polymerisation, be reacted with a reagent comprising a R2 group (e.g., 2-mercaptoethyl phosphonic acid) to yield a group —X—R2, where X is a linking group —CH2CH2SCH2CH2— and R2 is a FGN —P(O)(OH)2. In this sense, it will be appreciated that block A may comprise a mixture of (divalent) linking and (monovalent) terminal groups X. Furthermore, it will be appreciated that the specific groups mentioned in this paragraph are provided solely for the purpose of illustration, and that a person of ordinary skill in the art will recognise that X can take a variety of forms. Typically, X will be composed of fewer than 80 atoms, more suitably fewer than 40 atoms, even more suitably fewer than 20 atoms.
In embodiments, R1 is absent, or is
Suitably, the polymer comprises 1-10 wt % (relative to polymer mass), more suitably 3-9 wt %, most suitably 5-7 wt % of groups:
Block B may comprise a poly(ethylene oxide) backbone. Optionally, a proportion of the B block repeating units comprise a side chain independently selected from (1-2C)alkyl, —CH2OCH2CH═CH and alkyl-terminating poly(ethylene oxide).
Block B may be composed of poly(ethylene oxide), poly(propylene oxide), poly(allyl glycidyl ether) or a copolymer of two or more thereof. Most suitably, block B is composed of poly(ethylene oxide).
In embodiments, the polymer has a structure according to Formula (IA):
wherein L, Xa, m and n are as defined hereinbefore.
In embodiments, the polymer has a structure according to Formula (IB):
wherein Xa, R1, m and n are as defined hereinbefore.
In a second aspect, the present invention provides a process for the preparation of a polymer, the process comprising the steps of:
The tri-block copolymers of the first aspect can be straightforwardly prepared by ROCOP reaction. The use of CO2 as a reagent in ROCOP is particularly beneficial from an environmental standpoint.
The dihydroxy polyether provided in step (a) serves as a difunctional chain transfer agent initiator for the ROCOP reaction in step (b). It will be understood that the hydroxy groups are located at the ends of the polyether chain.
The polyether provided in step (a) may be any of those polyethers, and/or have any of those properties (e.g., molecular weight (Mn), glass transition temperature (Tg), dispersity (Ð), and/or number of repeating units (m)) recited hereinbefore in relation to block B of the polymer of the first aspect. Additionally/alternatively, the polycarbonate grown in step (b) may be any of those polycarbonates, and/or have any of those properties (e.g., glass transition temperature (Tg) and/or number of repeating units (n)) recited hereinbefore in relation to block A of the polymer of the first aspect. Additionally/alternatively, the tri-block copolymer prepared by the process may be any of those polymers, and/or have any of those properties (e.g., wt % of block A and/or molecular weight (Mn)) recited hereinbefore in relation to the polymer of the first aspect.
The process can be conducted in the presence of a suitable catalyst. Catalysts that are able to catalyse the ROCOP of an epoxide/oxetane with CO2 are known in the art. Suitably, the catalyst is a heterodinuclear catalyst, such as a Mg(II)Co(II) complex. A non-limiting example of a catalyst capable of performing step (b) is:
The process may further comprise an additional step of:
As described hereinbefore in relation to the first aspect, the epoxide/oxetane used in step (b) can take a variety of forms. Suitable oxetanes include 1,3-propylene oxide, 2,2-dimethyl oxetane and 3,3-dimethyl oxetane. Suitable epoxides include 2,3-dimethyl oxirane, terminal epoxides, glycidyl ethers and cyclic epoxides.
Terminal epoxides may have the structure:
wherein Rx is selected from hydrogen, (1-4C)alkyl, (2-4C)alkenyl, (1-4C)haloalkyl, aryl, aryl-(1-2C)alkyl, —(OCH2CH2)rOMe and —(CH2)sC(O)O—Rx1, in which r is 1-10, s is 0-6 and Rx1 is (1-5C)alkyl or aryl-(1-2C)alkyl. Particular non-limiting examples of Rx include hydrogen, methyl, ethyl, phenyl, —CH2Cl, —CH═CH2, —CH2C(O)OtBu, —C(O)OBn, —(CH2)1-4C(O)OMe and —(OCH2CH2)1-6OMe.
Glycidyl ethers may have the structure:
wherein Ry is selected from hydrogen, (1-4C)alkyl, (2-4C)alkenyl, (2-4C)alkynyl and —(CH2)tRy1, in which t is 0-4 and Ry1 is aryl, heteroaryl, carbocyclyl or heterocyclyl, wherein any ring in Ry is optionally substituted with one or more groups Ry2, and any (1-4C)alkyl in Ry is optionally substituted with Ry3; each Ry2 being independently selected from (1-3C)alkyl and nitro, and Ry3 being (1-4C)alkoxy or aryloxy. Particular non-limiting examples of Ry include hydrogen, (1-4C)alkyl, —CH2OCH2CH3, —CH2O—CH(CH3)2, —CH2—O—C6H5 and:
Cyclic epoxides may have the structure:
wherein D is a 5- to 7-membered carbocyclic or heterocyclic ring that is optionally fused or spiro-linked to 1 or 2 rings E, wherein each E is independently selected from carbocyclyl, heterocyclyl, aryl and heteroaryl, and wherein any of rings D and E are optionally substituted with one or more substituents RZ, each RZ being independently selected from (1-4C)alkyl, (2-4C)alkenyl, —(CH2)1-2Si(ORz1)3, —(CH2)1-2OSi(Rz1)3, and a group -Lz1-Lz2-Rz2, in which Rz1 is (1-2C)alkyl, Lz1 is absent or (1-3C)alkylene, Lz2 is absent, —O— or —C(O)O— and Rz2 is hydrogen, (1-6C)alkyl, (1-5C)haloalkyl, heterocyclyl, aryl or aryl-(1-2C)alkyl, wherein any ring in Rz2 is optionally substituted with (1-3C)alkyl or oxo. Particular, non-limiting examples of cyclic epoxides include:
Suitably, the epoxide or oxetane is an epoxide. More suitably, the epoxide is a cyclic epoxide. Even more suitably, the epoxide is a 6-membered cyclic epoxide. Most suitably, the epoxide is selected from:
The polyether provided in step (a) may be dried prior to carrying out step (b). Suitably, the polyether provided in step (a) is dried under vacuum.
Step (b) may be conducted with a solvent (e.g., diethyl carbonate) or without a solvent (i.e., in neat epoxide/oxetane). Step (b) may be conducted at a temperature of 50-150° C. (e.g., 90-110° C.).
Step (b) is suitably conducted at a CO2 pressure of <2 MPa. More suitably, step (b) is conducted at a CO2 pressure of <1 MPa. Even more suitably, step (b) is conducted at a CO2 pressure of <0.5 MPa. Most suitably, step (b) is conducted at a CO2 pressure of 0.05-0.2 MPa.
In a third aspect, the present invention provides a polymer obtained, directly obtained or obtainable by a process of the second aspect.
In a fourth aspect, the present invention provides an electrolyte comprising a mixture of a polymer of the first or third aspect and a metal salt.
The inventors have surprisingly determined that the polymers described herein are particularly suitable for use in an electrolyte, such as for a battery. The electrolytes display good thermal stability, as well as elastomeric and mechanical properties. The electrolytes also demonstrate good ionic conductivity at ambient and elevated temperatures, as well as good oxidative stability, suggesting they are compatible with high voltage cathodes.
The metal salt may be a Na, Li or K salt. Suitably the metal salt is a Li salt.
The metal salt may have the formula M+ X−, wherein M+ is selected from Na+, Li+ and K+, and X− is selected from BF4−, ClO4−, bis(fluorosulfonyl)imide, bis(trifluoromethanesulfonyl)imide, bis(oxalato)borate, a perfluoroalkylsulfonate (e.g., CF3SO3−), a polyfluoroalkyl sulfontate, PF6, AsF6−, cyano(trifluoromethanesulfonyl)imide, bis[(pentafluoroethyl)sulfonyl]imide, B(CN)4−, 4,5-dicarbonitrile-1,2,3-triazole, perylene diimide, 4,5-dicyano-2-(trifluoromethyl)imidazolium and combinations of two or more thereof. Suitably, M+ is Li+ and/or X− is bis(trifluoromethanesulfonyl)imide. Most suitably, M+ is Li+ and X− is bis(trifluoromethanesulfonyl)imide.
The electrolyte may comprise 0.1-80 wt % of the metal salt. Suitably, the electrolyte comprises 15-70 wt % of the metal salt. Electrolytes in which the polymer comprises a greater quantity of block A may be able to accommodate an increased quantity of metal salt.
In embodiments, the polymer comprises 60-80 wt % of block A and the electrolyte comprises 15-75 wt % of metal salt. Suitably, the electrolyte comprises 40-75 wt % of metal salt. Most suitably, the electrolyte comprises 55-70 wt % of metal salt. The metal salt is suitably lithium bis(trifluoromethanesulfonyl)imide.
In embodiments, the polymer comprises 20-40 wt % of block A and the electrolyte comprises 15-40 wt % of metal salt. Most suitably, the electrolyte comprises 20-35 wt % of metal salt. The metal salt is suitably lithium bis(trifluoromethanesulfonyl)imide.
In particular embodiments, the electrolyte comprises 40-75 wt % (e.g. 55-70 wt %) of metal salt; the polymer comprises 60-80 wt % (e.g., 65-75 wt %) of block A; and block B has a molecular weight (Mn) of 30-40 kg mol−1. The metal salt is suitably lithium bis(trifluoromethanesulfonyl)imide.
In particular embodiments, the electrolyte comprises 15-40 wt % (e.g. 20-35 wt %) of metal salt; the polymer comprises 20-40 wt % (e.g., 22-30 wt %) of block A; and block B has a molecular weight (Mn) of 30-40 kg mol−1. The metal salt is suitably lithium bis(trifluoromethanesulfonyl)imide.
In particular embodiments, the electrolyte comprises 15-40 wt % (e.g. 20-35 wt %) of metal salt; the polymer comprises 25-55 wt % (e.g. 32-42 wt %) of block A; and block B has a molecular weight (Mn) of 6-12 kg mol−1. The metal salt is suitably lithium bis(trifluoromethanesulfonyl)imide.
In a fifth aspect, the present invention provides a process for making an electrolyte, the process comprising the step of:
Step (ii) may comprise mixing the polymer and metal salt in a solvent. Any suitable solvent may be used. A non-limiting example of a suitable solvent is anhydrous THF.
The process may further comprise a step (iii) of drying the mixture resulting from step (ii).
Suitably, the mixture is dried at a temperature of 50-80° C., optionally under vacuum.
In a sixth aspect, the present invention provides a cathode for a battery, the cathode comprising a polymer of the first or third aspect, and/or an electrolyte of the fourth aspect.
The cathode may be a composite cathode. The composite cathode may comprise a cathode material (e.g. LiNi0.8Mn0.1Co0.1O2, known as NMC811), an electrically conductive additive (e.g. carbon) and either or both of a polymer of the first aspect and an electrolyte of the fourth aspect. The cathode material, electrically conductive additive and polymer and/or electrolyte may be provided as a mixture (e.g., an intimate and substantially homogeneous mixture) within the cathode. Within the composite cathode, particles of the cathode material may be coated with the polymer of the first aspect and/or the electrolyte of the fourth aspect. The composite cathode may also comprise a ceramic electrolyte (e.g., argyrodite Li6PS5Cl)
The composite cathode can be prepared by mixing (e.g., ball milling) the powders of the composite cathode components under dry (i.e., solvent-free) conditions, and then forming the resulting powder into a composite cathode (e.g. by cold-pressing under increased pressure).
The composite cathode can also be prepared by mixing the powders of the composite cathode components in a liquid (e.g xylene) to form a slurry and then casting the slurry onto a current collector (e.g., an Al current collector) using, for example, a doctor blade.
The composite cathode can also be prepared by coating the polymer of the first aspect and/or the electrolyte of the fourth aspect onto particles of the cathode material. The coating technique is suitably conducted in solution, followed by drying of the coated particles. The coated particles of the cathode material may then be mixed with the other cathode components (e.g., electrically conductive additive), for example, by a dry or wet technique, as described above.
The cathode may be for an alkali metal ion or an alkali metal battery (e.g., Li, Na or K). The cathode is suitably for a Li-ion or Li-metal battery.
In a seventh aspect, the present invention provides a battery comprising a polymer of the first or third aspect, an electrolyte of the fourth aspect, and/or a cathode of the sixth aspect.
In one arrangement, the battery comprises an electrolyte of the fourth aspect disposed between an anode and a cathode.
In another arrangement, the battery comprises a ceramic electrolyte (e.g., argyrodite Li6PS5Cl) disposed between an anode and a cathode, and wherein the battery further comprises an electrolyte of the fourth aspect disposed between the ceramic electrolyte and the cathode and/or anode.
In another arrangement, the battery comprises a cathode of the sixth aspect, wherein a ceramic electrolyte (e.g., argyrodite Li6PS5Cl) is disposed between the cathode and an anode, and wherein the cathode comprises an electrically conductive additive (e.g. carbon) and a cathode material (e.g. LiNi0.8Mn0.1Co0.1O2, known as NMC811), wherein particles of the cathode material are coated with the polymer of the first aspect and/or the electrolyte of the fourth aspect.
The battery may be an alkali metal ion or an alkali metal battery (e.g., Li, Na or K). The battery is suitably a Li-ion or Li-metal battery.
In an eighth aspect, the present invention provides a use of a polymer of the first or third aspect in the manufacture of a battery or a battery component (e.g. an electrolyte or a cathode).
The following numbered statements 1 to 79 are not claims, but instead describe particular aspects and embodiments of the invention:
A-B-A (I)
wherein L, Xa, m and n are as defined in any one of the preceding statements.
One or more examples of the invention will now be described, for the purpose of illustration only, with reference to the accompanying figures:
Materials: 4-vinyl cyclohexene oxide, vCHO purchased from ACROS and purified by drying over CaH2 and fractional distillation. Poly(ethylene oxide) (PEO) was purchased from Sigma Aldrich and dried under vacuum at 110° C. for 24 h prior to use. Anhydrous diethyl carbonate (DEC) was purchased from Sigma Aldrich, degassed by freeze-pump thaw (3 cycles) before being stored over 3 Å molecular sieves under nitrogen. Lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) was purchased from Sigma Aldrich and dried under vacuum at 110° C. for 48 h before being stored in a glovebox. Lithium bis(fluorosulfonyl)imide (LiFSI) was purchased from Solvionic and stored in a glovebox prior to use. CP Grade (BOC, 99.995%) CO2 was used for all polymerizations and dried through two VICI purifier columns. Anhydrous THF for polymer electrolyte film formation was obtained from Solvent Purification System (SPS), degassed by freeze-pump thaw (3 cycles) and stored in a glovebox over 3 Å molecular sieves. All other reagents were purchased from Sigma Aldrich and used as received.
NMR: 1H, 31P {1H} and 13C{1H}NMR were recorded on a BrukerAvance Ill HD 400 MHz spectrometer. DOSY spectra were recorded on Bruker Avance Ill HD 500 MHz spectrometer.
Size Exclusion Chromatography (SEC): Polymer (2-10 mg) dissolved in HPLC grade CHCl3 (1 mL) was syringe filtered through 2 μm filters before being injected into an Agilent PL GPC-50 instrument, with two PSS SDV 5 μm linear M columns heated to 30° C. HPLC grade CHCl3 was used as the eluent at a flow rate of 1.0 mL min−1 with RI detection calibrated using a series of narrow molecular weight polystyrene standards. Agilent SEC post-run program was used to analyze the data.
Differential Scanning Calorimetry (DSC): These were recorded for purified polymer samples and solid polymer electrolyte films on a Mettler Toledo DSC3 Star calorimeter under a nitrogen flow (80 mL min−1). Samples were heated to 200° C. and held for 5 minutes to remove any thermal history before heating and cooling from −80 to 200° C. at a rate of 10° C. min−1. Glass transition temperatures (Tg) were determined from the midpoint of the transition in the second heating curve.
Thermoqravimetric Analysis (TGA): Measured on Mettler-Toledo Ltd TGA/DSC 1 system. Powder polymer samples were heated from 30 to 500° C. at a rate of 5° C. min−1, under N2 flow (100 mL min−1).
Phosphorus end group tests: Following a literature procedure22, to polymer (40 mg) dissolved in CDCl3 (0.4 mL) was added 40 μL of solution containing Cr(acac)3 (5.5 mg) and internal standard, bisphenol A (400 mg) in pyridine (10 mL) followed by 40 μL of 2-chloro-4,4,5,5-tetramethyl dioxaphospholane.
Rheology: Shear storage (G′) and loss moduli (G″) were measured on a TA instruments Q800 with 25 mm stainless steel platens. Measurements were conducted in the linear viscoelastic region as determined by an amplitude sweep conducted at 30 and 200° C. The polymer electrolyte was heated from 30 to 200° C. at 2° C. min−1, 1 Hz frequency, 0.1% amplitude strain. Frequency sweeps were also conducted between 3° and 100° C. at 10° C. intervals.
Dynamic Mechanical Thermal Analysis (DMTA): Storage (E′) and loss moduli (E″) were measured on a TA instruments Q850 in tension mode at 0.1% strain, 1 Hz frequency from −60 to +180° C. at a heating rate of 3° C. min−1.
ATR-FTIR: IR spectra of thin films were recorded on a Perkin Elmer Spectrum 100 (FT-IR) with an AT-IR crystal or a Varian FT-IR 3100 spectrophotometer (Golden Gate). All the IR measurements were performed in the reflection mode at a resolution of 4 cm−1.
Tensile Testing: Dumbbell specimens were cut from polymer electrolyte films according to ISO 527-2, specimen type 5B with Zwick ZCP020 cutting press (length=35 mm, gauge length=10 mm, width=2 mm). Monotonic uniaxial extension experiments were carried out on a Shimadzu EZ-LZ Universal testing instrument at an extension rate of 10 mm min−1. An external camera was used to calculate the Young's Modulus, Ey within the 0.025-0.25% strain region. 10 Specimens were tested for each material. Cyclic tensile tests were conducted to 20 or 200% strain at a rate of 10 mm min−1. 10 Cycles were measured for each specimen, 3 specimens for each sample.
Compression Testing: Polymer electrolytes were pressed into pellets (10 mm diameter, 2 cm thick) using a Carver Hotpress at 80° C. and a 10 mm diameter die set. Clear, colourless pellets were inspected to ensure they were free from air bubbles prior to testing. Compression experiments were carried out on a Shimadzu EZ-LZ Universal testing instrument fit with compression jigs at a rate of 10 mm min−1.
180° Peel Tests: Solid polymer electrolyte (0.4 g) in THF (4 ml) was cast using a doctor blade (80 μm wet film thickness) onto alumina sheets (20×80 mm), and the solvent was allowed to evaporate at RT (
Electrochemical Impedance Spectroscopy (EIS): Discs of polymer electrolyte films were cut using a cutting press (16 or 18 mm diameter). The SPE discs were then sandwiched between two gold block electrodes (Au|SPE|Au) and placed inside a CESH cell. Impedance measurements were conducted between 1 Hz and 0.1 MHz using Biologic Impedance Analyzer over 30 to 80° C. with 0.5 h soak time at each temperature. The resulting Nyquist curves were analyzed using EC-labs software to fit an equivalence circuit and determine resistance, R. Conductivity (σ) was then determined as: σ=//AR, where A=the polymer electrolyte disc area and/the electrolyte thickness (0.1-0.45 mm, see Table S4).
Linear Sweep Voltammetry (LSV): These were recorded for CEC(35, fPC) prepared as polymer electrolyte discs (as described in EIS measurements above). Measurements were recorded at RT vs Lithium foil in a PEEK cell with stainless steel (SS) counter-electrode (Li|SPE|SS). The open-circuit voltage (OCV) was first recorded for 12 hours to ensure stability before conducting experiments at 1 mV s−1 from the OCV to 5 V. For lead polymers P1-P3, LSV was also measured vs lithium metal with a polymer-carbon nanofibre composite counter electrode at 60° C. and 0.1 mV s−1 from the OCV to 6 V.
Small Angle X-ray Scattering (SAXS): Polymer films were submitted to Harwell Diamond Light Source in a solid sample grid for SAXS analysis (DL-SAXS, P38 instrument). Scans (3×5 min) were conducted at camera lengths of 4.5 and 1 m, beam energy=9.2 keV (using the Ga MetalJet). SAXS curves reported are an average of the 3 scans measured from data collected at 1 m. Samples were not annealed prior to testing to reflect experimental conditions of tensile testing.
General polymerisation procedure: Taking CEC(35, 0.26) as an example (for notation see Table 1), PEO with Mn=35 kg mol−1 (9.3 g, 0.27 mmol, 20 equiv.) was dried under vacuum at 110° C. for 24 h. At room temperature in an inert atmosphere, vCHO (10 ml, 80 mmol, 6000 equiv.) and LMgCo(OAc)2 (10 mg, 0.013 mmol, 1 equiv.) were added. DEC (20 ml) was then added to the reaction mixture, and any remaining catalyst residue was rinsed into the solution. The nitrogen headspace was then replaced with CO2 by 3 vacuum-CO2 cycles before placing the solution in a pre-heated oil bath to 100° C. Aliquots were taken from the reaction mixture at various time points under a stream of CO2 gas and analyzed by 1H NMR spectroscopy to monitor the conversion of vCHO monomer (3.1-3.2 ppm) to polycarbonate (4.76 ppm). For CEC(35, 0.26), after 6 hours, the reaction was cooled to room temperature and quenched by adding benzoic acid (˜16 mg, 0.13 mmol, 10 equiv.) dissolved in the minimum amount of dichloromethane. The polymer was isolated by precipitation on pouring the solution into a large excess of diethyl ether or methanol (˜400 ml) and vacuum filtration. The polymer was further purified by rinsing the filtrate with ether/methanol and toluene to obtain a pure white powder (12.5 g, 90%). NB. for fPC>0.5, methanol should be used as the antisolvent and the product not rinsed with toluene; for Mn,PEO≤8 kg mol−1, hexane should be used to precipitate the polymer.
General procedure for thiolene reaction: To CEC(35, 0.26) (1 g, 1.6 mmol C═C, 1 equiv. C═C) dissolved in degassed THF (10 ml), MEPA (66 mg, 0.46 mmol, 0.3 equiv.) followed by DMPA (12 mg, 0.046 mmol, 0.03 equiv.) was added. NB. for polymers with fPC<0.3, gentle heating is required to disrupt PEO crystallinity and dissolve the block polymer in THF. The solution was then exposed to UV light for 0.5 h with stirring before precipitating into diethyl ether. The polymer was isolated as a white powder/material and washed twice with diethyl ether (˜1 g).
Synthesis of LMgCo(OAc)2 catalyst: The macrocycle ligand, HL2 was synthesized as per previous literature reports. The Mg(II)Co(II) heterodinuclear complex was synthesized as previously reported:23
Triblock polymers were synthesized using commercial PEO (α,ω-hydroxyl end terminated) as a bifunctional macro-initiator. Readily available and narrow disperse PEO with molar masses ranging from 1-100 kg mol−1 (23-2272 EO repeat units) were considered. Chain extension of the polyether mid-segment with polycarbonate (PC) end-blocks was achieved by the controlled ring-opening copolymerization (ROCOP) of CO2 with vCHO, catalyzed by heterodinuclear complex LMgCo(OAc)2 (
Conversion of vCHO monomer to polycarbonate was determined by 1H NMR analysis of the crude reaction mixture. The resulting triblock polymers, PC-b-PEO-b-PC, were isolated as white powders in high yield (85-90%) by precipitation from diethyl ether.
Size-elusion chromatography (SEC) of the purified copolymers confirmed an increase in molecular mass (Mn) on PEO chain extension with PC whilst maintaining narrow dispersity (D 1.13-1.23), supporting block formation over mixtures of unconnected PEO and PC homopolymers (
]e
aReaction conditions: 100° C..
bNomenclature CEC(Mn,PEO, fPC) where Mn,PEO is the number-average molecular mass defined by the manufacturer and verified by SEC and fPC is the volume fraction of PC:
g mol−1) and vCHO/CO2 (168.23 g mol−1), respectively. MPEO and MPC are the number averaged molecular weights of the PEO and PC blocks in kg mol−1. Molar volumes VPEO, VPC were calculated by v = M/ρ using densities (g cm−3) of PC and PEO of 1.10 g cm−3 and 1.12 g cm−3.
cDetermined by relative 1H NMR integration of PEO (3.64 ppm) vs PC (5.75 or 2.42 ppm) using PC repeat unit of 168.23 g mol−1.
dCatalyst loading (catalyst/epoxide).
evCHO conversion to PC determined from 1H NMR analysis of crude reaction mixture.
fReaction time.
gOverall theoretical molar mass, Mn calculated based on initial monomer/initiator ratio, Mn,PEO and conversion of vCHO to PC. Mn and dispersity ( ) by SEC measured with CHCl3 eluent,
Radical mediated thiol-ene ‘click’ chemistry can be used to introduce functional groups to polymer backbones with high efficiency. Phosphonic —PO(OH)2 functional groups were grafted onto the polycarbonate blocks to tailor adhesive properties (
PC/PEO microphase separation into physically crosslinked 3D networks is anticipated and illustrated in
In
Li-ions can coordinate to both the carbonate groups and PEO ethereal oxygens. The presence of Li in the PC domains and PEO mid-segments was corroborated by FTIR spectroscopy of the SPE films whereby a broadening of the carbonate C═O stretch and a shift to lower wavenumbers (1744-1739 cm−1) with 0-66 wt % LiTFSI was observed (
MEPA functional groups were introduced along the backbone of the hard PC domains to improve adhesion via coordination or hydrogen bonding to active inorganic materials. Adhesion plays a role in maintaining interfacial contact between the active materials in the composite cathode; loss of contact during continuous volume changes of the active material leads to degradation of the electrochemical performance. Poor adhesion can thus result in capacity loss and low long-term battery stability. Adhesion occurs through wetting of the polymer electrolyte on the surface of the active inorganic material. Typically, this occurs when the surface energy of the polymer is less than that of the inorganic solid. The surface energy of the polymer electrolyte films was measured using Owens/Wendt Theory and in all cases, the polymers would be expected to wet the surface of the inorganic cathode material (Table 2).
Wetting of polymer on surface of cathode material: γpolymer<γactive material. Contact Angle Approach using Owens/Wendt Theory with water, glycol and diiodomethane.
where σL/σS=overall surface tension of the wetting liquid/overall surface energy of the solid, σL/SD=dispersive component of the surface tension of the wetting liquid/surface energy of the solid; σL/SP=polar component of the surface tension of the wetting liquid/surface energy of the solid; σSL=the interfacial tension between the solid and the liquid, and θ=the contact angle between the liquid and the solid.
180° peel tests were used to gauge the adhesive capabilities of the SPEs to the cathode material using alumina as a model substrate for the oxide cathode surface (
FTIR was used to probe the binding of the phosphonic acid grafted polymer to the actual NMC cathode surface (
Electrochemical impedance spectroscopy (EIS) was used to measure the ionic conductivities of polymer electrolytes. Films were punched into discs with 0.09-0.45 mm thicknesses, measured by digital microscopy (Table 3). Measurements were performed as a function of temperature (RT-80° C.) and LiTFSI content. For CEC(35,0.37), an optimal 28 wt % LiTFSI content was determined or a Li-ion to every 13 EO or carbonate coordinating environments: r=[EO+CO]/[Li]=13 (
Film thickness is important for determining conductivity from impedance data and for measuring mechanical properties. To verify accurate film thicknesses Keyence VHX 7000 Digital Microscope (14 measurements over 2 cross-sections) was used and values correlated to those obtained using calipers (3 measurements).
As hypothesized, the block polymers show higher oxidative stability with increasing fPC (vs Li+/Li with SS counter-electrode,
Typically, the temperature dependence of lithium-ion conductivity follows the Vogel-Tamman-Fulcher (VTF) model:
where T0=Tg−50K and parameters A (relating to the free charge carrier concentration) and Ea (activation energy for ion transport) can be obtained by a linear fit. Generally, increasing fPC or grafted MEPA content (i.e. physically crosslinking) had little impact on Ea, but a larger influence on A. Whereas, increasing salt content and PEO MW influenced both Ea and A (
Solid-state 7Li NMR for P1-P3 shows increasingly downfield shifts following the same order as conductivity (
P1-P3 block copolymers show higher conductivities than random PC/EO copolymers reported in the literature (Table 1). This observation might suggest a role played by the phase-separated morphologies providing channels for ion movement. SAXS profiles conducted of the polymer electrolyte films at RT suggests some long-range ordering with hexagonally packed cylinders or FCC spherical morphologies of PC in a PEO matrix for P1 and P3, with domain spacings (D) based on the principal scattering peak (q*) of 24 and 36 nm, respectively (
7Li Diff
19F Diff
Initial investigations focused on the behavior of the SPEs under tension. Dumbbell specimens for tensile testing experiments were cut from solid polymer electrolytes films according to specimen type-5B ISO standard 527-2. The Young's Modulus (Ey) was determined from the initial linear stress-strain region (0.025-0.25% strain). All samples were stored in a glovebox prior to testing to minimize the influence of water ingress on the mechanical properties
Mechanical properties for P1-P3 were also investigated by rheology in the linear viscoelastic region (determined by an amplitude sweep at 1 Hz).
aGlass transitions from DSC.
bIonic conductivity
cShear storage moduli at 30° C.
dLithium transference number at 60° C.
The cell performance of the three lead polymers were investigated. P1 is a typical thermoplastic elastomer, P2 is a polymer-in-salt composition with high G′, and P3 is a low-temperature melt-processable soft elastomer. Prior to cell fabrication, the oxidative stability of these lead polymers was evaluated by linear sweep voltammetry at a low scan rate of 0.1 mV s−1 vs lithium and a carbon-polymer composite (
Composite cathodes were prepared with P1, P2 and P3 with carbon nanofibers for electrical conductivity, polycrystalline NMC811 high-voltage cathode material and LPSCI ceramic electrolyte. The powders were homogeneously mixed by ball-milling and formed into a pellet by cold-pressing (50 MPa). Although there remain questions of scalability of the dry mixing method, the use of solvents resulted in higher degradation of LPSCI and with an ionically conductive polymer, concerns regarding partially blocked ion conduction pathways when dry mixing non-conducting binders are lessened. The cell was assembled: LTO|LPSCI|SPE-NMC composite cathode and charged-discharged at 60° C., 1 MPa stack pressure, 0.5 C rate.
Initial discharge capacity shows P2 and P3 give capacities higher than no-polymer (P0), PEO and P1 (
Despite its high conductivity advantages, Li6PS5Cl argyrodite electrolyte (LPSCI) is highly reactive, and its conductivity is dependent on the crystal structure. To assess the chemical stability of the polymer electrolytes vs Li6PS5Cl, conductivity measurements were conducted (by electrochemical impedance spectroscopy) of polymer electrolytes sandwiched between LPSCI (SPE|LPSCI|SPE). The cell was heated at 60° C., and impedance measurements were recorded at regular 10 h intervals at RT (the lower temperature to evaluate differences between the polymers). Whereas PEO shows increasing resistance with time, indicating chemical reactivity and degradation of LPSCI as noted previously by Janek et al, P2 decreases. After 10 days at 60° C., little difference in conductivity behaviour was observed, indicating good chemical stability vs LPSCI (
While specific embodiments of the invention have been described herein for the purpose of reference and illustration, various modifications will be apparent to a person skilled in the art without departing from the scope of the invention as defined by the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2203752.7 | Mar 2022 | GB | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/GB2023/050634 | 3/16/2023 | WO |
