Patent Application
20230096123
The present disclosure describes solid-polymer electrolytes. The present disclosure also describes methods of making solid-polymer electrolytes and uses of solid-polymer electrolytes.
In an aspect, the present disclosure provides solid-polymer electrolytes. A solid-polymer electrolyte comprises a cross-linked polymer network. A cross-linked polymer network may comprise a plurality of groups (e.g., cross-linked groups, such as, for example, cross-linked difunctional polyether groups, cross-linked difunctional ionic groups, and the like, non-crosslinked groups, such as, for example “dangling” groups, or a combination thereof); and a plurality of cross-linked multifunctional crosslinker groups. Individual cross-linked difunctional polyether groups and/or individual cross-linked difunctional ionic groups and individual cross-linked multifunctional crosslinker groups are connected by at least one crosslinking group (e.g., comprising a thioether group, such as for example, a carbon-sulfur bond). A solid-polymer electrolyte may comprise one or more metal salt(s), one or more tethered ionic group(s), or a combination thereof, and/or a liquid electrolyte. A solid-polymer electrolyte may or may not comprise a liquid electrolyte. In various examples, a cross-linked difunctional polyether group is structurally derived from (e.g., formed from) a difunctional polyether monomer and/or a cross-linked difunctional ionic group is structurally derived from (e.g., formed from) a difunctional ionic monomer and/or a “dangling” group is structurally derived from (e.g., formed from) a “dangling” group monomer and/or a cross-linked multifunctional crosslinker group is structurally derived from (e.g., formed from) multifunctional crosslinker monomer. At least a portion of or all of the “dangling” groups may comprise a charged group. In various examples, charged group(s) individually comprise one or more anion(s) and one or more cation(s). A solid-polymer network may comprise a plurality of crystalline domains. A solid-polymer network may comprise a plurality of crystalline domains and a plurality of amorphous domains.
In an aspect, the present disclosure provides methods of making solid-polymer electrolytes. In various examples, a solid-polymer electrolyte is made by a method of the present disclosure. A method may be an ex situ method or an in situ method. A method of making a solid-polymer electrolyte (e.g., a solid-polymer electrolyte of the present disclosure) comprises: forming a reaction mixture including one or more difunctional polyether monomer(s) (e.g., PEG diallyl ether monomers and the like) (e.g., comprising a polyether group and two reactive groups (e.g., alkenyl(s), alkynyl(s), acryloyl(s), thiol group(s), and the like, and combinations thereof)), and/or one or more difunctional ionic monomer(s) (e.g., comprising one or more ionic group(s) (e.g., one or more anionic group(s)) and two reactive groups (e.g., alkenyl(s), alkynyl(s), acryloyl(s), thiol group(s), and the like, and combinations thereof)) and/or one or more “dangling” group monomer(s) (e.g., comprising one reactive group (e.g., alkenyl, alkynyl, acryloyl, thiol group, and the like); one or more multifunctional crosslinking monomer(s) comprising two or more (e.g., 2, 3, 4, 5, 6, etc.) reactive groups (e.g., alkenyl(s), alkynyl(s), acryloyl(s), thiol group(s), and the like, and combinations thereof); and optionally, one or more solvent(s) (which individually may be a component of a liquid electrolyte). Without intending to be bound by any particular theory, it is considered that the optionally present one or more difunctional polyether monomer(s), the optionally present one or more ionic group monomer(s), the optionally present one or more “dangling” group monomer(s) and/or one or more multifunctional crosslinking monomer(s) react to form the solid-polymer electrolyte. A monomer or monomers may be referred to as precursor or precursors, respectively.
In an aspect, the present disclosure provides uses of solid-polymer electrolytes. The solid-polymer electrolytes may be solid-polymer electrolytes of the present disclosure. A device may comprise one or more solid-polymer electrolyte(s) of the present disclosure. Non-limiting examples of devices include batteries, supercapacitors, fuel cells, and the like. The solid-polymer electrolyte(s) may be formed in situ in the device.
Rechargeable lithium batteries have revolutionized the fields of consumer electronics and electric vehicles since their first successful commercialization by Sony in 1991. Configurations with lithium metal as the anode have attracted significant interest due to their high volumetric and gravimetric energy densities. The commercialization of lithium metal batteries (LMBs), however, has been hindered by the notorious problem of unstable, non-planar electrodeposition at the anode surface, which leads to formation of rough, mossy, or dendritic morphologies during battery recharge that can lead to premature battery failure. Extensive research efforts have focused on the suppression of lithium dendrites by means of salt additives, coatings on the lithium metal anode, single-ion conductors, and high modulus solid-state electrolytes. At current densities below the diffusion limit, the growth of Li dendrites is thought to occur in three stages. The first stage involves the formation of a passivation layer by reduction of electrolyte components (such as solvents, salts, or additives) in contact with the electrode. Termed the solid electrolyte interphase (SEI), this layer was recently investigated by means of focused ion beam (FIB) cryogenic SEM and electron spectroscopy techniques and shown to be highly heterogeneous and far thicker than the analogous SEI formed on graphite anodes in lithium-ion batteries (LIBs). In the second stage, Li transport through the SEI produces heterogeneous deposits that lead to the nucleation of dendrites at zones of high conduction. Finally, the passivation layer continuously breaks and reforms by reaction with the electrolyte, promoting continuous growth of the dendrite into a ramified structure with the growth direction determined by the least reactive crystallographic facet of metallic Li.
Citation or identification of any document in this application is not an admission that such a document is available as prior art to the present disclosure.
For a fuller understanding of the nature and objects of the disclosure, reference may be made to the following detailed description taken in conjunction with the accompanying figures.
Although claimed subject matter will be described in terms of certain examples and embodiments, other examples and embodiments, including examples that do not provide all of the benefits and features set forth herein, are also within the scope of this disclosure. Various structural, logical, and process step changes may be made without departing from the scope of the disclosure.
Ranges of values are disclosed herein. The ranges set out a lower limit value and an upper limit value. Unless otherwise stated, the ranges include the lower limit value, the upper limit value, and all values between the lower limit value and the upper limit value, including, but not limited to, all values to the magnitude of the smallest value (either the lower limit value or the upper limit value).
As used herein, unless otherwise stated, the term “group” refers to a chemical entity that is monovalent (i.e., has one terminus that can be covalently bonded to other chemical species), divalent, or polyvalent (i.e., has two or more termini that can be covalently bonded to other chemical species). The term “group” also includes radicals (e.g., monovalent and multivalent, such as, for example, divalent radicals, trivalent radicals, and the like). Illustrative non-limiting examples of groups include:
The present disclosure describes solid-polymer electrolytes. The present disclosure also describes methods of making solid-polymer electrolytes and uses of solid-polymer electrolytes.
In an aspect, the present disclosure provides solid-polymer electrolytes. Non-limiting examples of solid-polymer electrolytes are described herein.
A solid-polymer electrolyte comprises a cross-linked polymer network. A cross-linked polymer network may comprise a plurality of groups (e.g., cross-linked groups, such as, for example, difunctional polyether groups (which may be referred to as cross-linked difunctional polyether groups), difunctional ionic groups)which may be referred to as crosslinked ionic groups), and the like, non-crosslinked groups, such as, for example “dangling” groups, or a combination thereof); and a plurality of multifunctional crosslinker groups (which may be referred to as crosslinked multifunctional groups). Individual difunctional polyether groups and/or individual difunctional ionic groups, and individual multifunctional crosslinker groups are connected (e.g., covalently bonded to another group) by at least one crosslinking group (e.g., comprising a thioether group, such as for example, a carbon-sulfur bond). A solid-polymer electrolyte may comprise one or more metal salt(s), one or more tethered ionic group(s), or a combination thereof, and/or a liquid electrolyte. A solid-polymer electrolyte may or may not comprise a liquid electrolyte.
A group may be structurally derived from (e.g., formed by) a polymerization reaction involving the respective monomer. In various examples, a cross-linked difunctional polyether group is structurally derived from (e.g., formed from) a difunctional polyether monomer and/or a cross-linked difunctional ionic group is structurally derived from (e.g., formed from) a difunctional ionic monomer and/or a “dangling” group is structurally derived from (e.g., formed from) a “dangling” group monomer and/or a cross-linked multifunctional crosslinker group is structurally derived from (e.g., formed from) multifunctional crosslinker monomer.
At least a portion of or all of the “dangling” groups may comprise a charged group. In various examples, charged group(s) individually comprise one or more anion(s) and one or more cation(s).
A solid-polymer electrolyte may comprise one or more ion(s) tethered via one or more covalent bond(s) to the polymer network. In various examples, a solid-polymer electrolyte comprises one or more ion(s) tethered via one or more covalent bond(s) to the polymer network via one or more “dangling” group(s).
A solid-polymer electrolyte may further comprise one or more non-crosslinked group(s) (which may be referred to as “dangling” groups) (e.g., groups having at least one terminal group not covalently bound to the cross-linked polymer network) covalently bonded to the cross-linked polymer network via a group comprising a thioether group (e.g., a carbon-sulfur bond). In various examples, a non-crosslinked group is structurally derived from (e.g., formed from) a non-crosslinked group monomer.
A solid-polymer electrolyte may comprise a network of interconnected (covalently crosslinked) polymer chains, which may be entangled polymer chains. A solid-polymer electrolyte may comprise amorphous and/or crystalline domains. In various examples, a solid-polymer electrolyte comprises a network of interconnected (covalently crosslinked) polymer chains, which may be entangled polymer chains, and amorphous and/or crystalline domains.
A solid-polymer network may comprise a plurality of crystalline domains. Without intending to be bound by any particular theory, it is considered that crystalline domains are generally observed for higher molecular weight PEO monomers (e.g., Table 1 of the Example). It may be desirable that the polymer network is predominantly or completely amorphous. A polymer network may comprise a minor amount (e.g., number) of crystalline region(s).
A solid-polymer network may comprise a plurality of crystalline domains and a plurality of amorphous domains. The amount of crystallinity in the material generally depends upon the molecular weight of the polyether monomer used (e.g., at 3,000 g/mol and up, crystalline regions may be observed (e.g., Table 1 of the Example)).
The presence or absence of crystalline domains and/or amorphous domains can be determined by methods known in the art. In various examples, the presence or absence of crystalline domains and/or amorphous domains is determined by differential scanning calorimetry (DSC).
It may be desirable that the solid-polymer electrolyte be predominantly amorphous. In an example, a solid-polymer network does not have any crystalline domains (e.g., no observable domains determined by, for example, microscopy).
A solid-polymer electrolyte may have one or more desirable propert(ies). In various examples, a solid-polymer electrolyte has one or more desirable mechanical propert(ies) (such as, for example, modulus, which may be a storage modulus and/or be 0-5 MPa (e.g., 0-2 MPa), including all integer MPa values and ranges therebetween), low Tg (e.g., −60° C. to 0° C., including all 0.1° C. values and ranges therebetween), ionic conductivity (e.g., as a solid-state electrolyte containing a metal salt (such as, for example, LiTFSI) or a gel electrolyte containing a metal salt and liquid electrolyte (such as, for example, LiTFSI and EC/DMC (1:1, v:v)), or a combination thereof.
A solid-polymer electrolyte, which may be a gel electrolyte, may comprise one or more conducting salt(s). Non-limiting examples of conducting salts include metal salts, tetraalkyl ammonium salts, and the like, and combinations thereof. The conducting salt(s) individually comprise one or more conducting cation(s). Non-limiting examples of conducting cations include metal cations, tetraalkyl ammonium ions, and the like, and combinations thereof. In various examples, conducting cations, which may be metal cations, include lithium cations, sodium cations, potassium ions, aluminum ions, magnesium ions, tetraalkyl ammonium ions, and the like, and combinations. Other non-limiting examples of conducting cations include NR4+, where R is independently a C1 to C6 alkyl group, and the like. Non-limiting examples of conducting salts, which may be metal salts, include triflate salts M+/NR4+−OTf, carboxylate salts (e.g., M+/NR4+−O2CF3 and the like), hexaflurophosphate salts (e.g., M+/NR4+−PF6), tetrafluoroborate salts (e.g., M+/NR4+−BF4), perchlorate salts (e.g., M+−OCl4), (trifluoromethanesulfonyl)imide salts (M30 /NR4+−N(SO2CF3)2), M+/NR4+−NR(OS2F) (where R═H, alkyl, aryl, and the like), metal nitrate salts, metal cation/alkylammonium halide salts (e.g., M+/NR4+−Cl, and the like), and the like, where M+/metal may be Li+, Na+, K+, Mg+, Al+3 (in this case the number of single charged anions in the above examples would triple), or the like. In various examples, the conducting salt loading (e.g., metal salt loading or the like), described in terms of the ratio of Lewis basic coordinating groups (O and S) to cation(s) (e.g., Li+, where the ratio would be ([O or S]:[Li+])) ranges from 100:1 to 1:3 (e.g., 15:1 to 25:1, such as, for example, 18:1), including all 0.1 range values and ranges therebetween.
A solid-polymer electrolyte may comprise a liquid electrolyte. In various examples, the liquid electrolyte comprises one or more liquid(s) chosen from carbonates (such as, for example, ethylene carbonate (EC), propylene carbonate (PC), fluorinated ethylene carbonates (e.g., fluoroethylene carbonate (FEC),
and the like), vinylene carbonate (VC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), 1,2-dimethoxyethane (DME), and the like),
where n is 1, 2, or 3 (e.g., diglyme (DEGDME), tetraglyme (TEGDME), and the like), and the like, and combinations thereof and/or one or more conducting salt(s) (e.g., metal salt(s), tetraalkylammonium salt(s), and the like, and combinations thereof), the conducting salt(s) individually comprising one or more conducting cation(s) (e.g., metal cation(s), tetraalkyl ammonium ion(s), and the like, and combinations thereof), such as, for example, lithium cation, sodium cation, potassium cation, aluminum cation, magnesium cation, ammonium ion, or the like, or a combination thereof). Non-limiting examples of conducting cations include NR4+, where R is independently a C1 to C6 alkyl group, or the like. Non-limiting examples of conducting salts include M+/NR4+−OTf, carboxylate salts (e.g., M+/NR4+−O2CF3, M+/NR4+−PF6, M+/NR4+−BF4, M+/NR4+−OCl4, metal cation/alkylammonium nitrate salts, metal cation/alkylammonium nitrate halide salts (e.g., M+/NR4+−Cl, and the like), and the like, where M/metal is Li+, Na30 , K30 , Mg+, Al+3 (in this case the number of single charged anions in the above examples would triple).
The metal salt(s) may be present at various amounts. In various examples, metal salt(s) is/are present in the composition at a concentration of 0.1 M to 5 M (e.g., in the liquid electrolyte), including all 0.1 M values and ranges therebetween.
In the case where a solid-polymer electrolyte comprises a one or more conducting salt(s), which may be metal salt(s), and/or one or more liquid(s), the metal salt(s) and/or liquid(s) may be one or more ionic liquid(s). In various examples, the liquids are chosen from lithium ionic liquids, sodium ionic liquids, potassium ionic liquids, aluminum ionic liquids, magnesium ionic liquids, ammonium ionic liquids, and the like, and combinations thereof. Suitable ionic liquids are known in the art and/or commercially available.
In an aspect, the present disclosure provides methods of making solid-polymer electrolytes. In various examples, a solid-polymer electrolyte is made by a method of the present disclosure. A method may be an ex situ method or an in situ method. Non-limiting examples of methods of making solid-polymer electrolytes are described herein. A method of making a solid-polymer electrolyte (e.g., a solid-polymer electrolyte of the present disclosure) comprises: forming a reaction mixture including: one or more difunctional polyether monomer(s) (e.g., PEG diallyl ether monomers and the like) (e.g., comprising a polyether group and two reactive groups (e.g., alkenyl(s), alkynyl(s), acryloyl(s), thiol group(s), and the like, and combinations thereof)), and/or one or more difunctional ionic monomer(s) (e.g., comprising one or more ionic group(s) (e.g., one or more anionic group(s)) and two reactive groups (e.g., alkenyl(s), alkynyl(s), acryloyl(s), thiol group(s), and the like, and combinations thereof)) and/or one or more “dangling” group monomer(s) (which may be referred to as non-crosslinking monomer(s) or non-crosslinked monomer(s)) (e.g., comprising one reactive group (e.g., alkenyl, alkynyl, acryloyl, thiol group, and the like); one or more multifunctional crosslinking monomer(s) comprising two or more (e.g., 2, 3, 4, 5, 6, etc.) reactive groups (e.g., alkenyl(s), alkynyl(s), acryloyl(s), thiol group(s), and the like, and combinations thereof); and optionally, one or more solvent(s) (which individually may be a component of a liquid electrolyte). In various examples, the individual monomers have one or more groups that can react with a group on another monomer to form a cross-linking group. In various examples, the reaction mixture comprises at least one difunctional monomer. In various examples, the reaction mixture comprises at least one difunctional ionic monomer. In various examples, the reaction mixture comprises at least one difunctional monomer and at least one difunctional ionic monomer. In various examples, the reaction mixture comprises at least one difunctional monomer and at least one difunctional ionic monomer and at least one non-crosslinking monomer. In various examples, the reaction mixture does not comprise a non-crosslinking monomer. Without intending to be bound by any particular theory, it is considered that the optionally present one or more difunctional polyether monomer(s), the optionally present one or more ionic group monomer(s), the optionally present one or more “dangling” group monomer(s) and/or one or more multifunctional crosslinking monomer(s) react to form the solid-polymer electrolyte. A monomer or monomers may be referred to as precursor or precursors, respectively.
In various examples, the difunctional polyether group monomer(s), the difunctional ionic group monomer(s), and the “dangling” group monomer(s) each individually comprises 0-100% (e.g., % by weight or mol %), including all 0.1% values and ranges therebetween, of the crosslinking monomer(s) and/or non-crosslinking monomer(s), or non-multifunctional crosslinking monomers, and/or the ratio of crosslinking monomer(s) and/or non-crosslinking monomer(s) to non-multifunctional crosslinking monomers is 2:1 to 2:1 (e.g., 1:1, 1.1:1 to 1:1.1, or 1.5:1 to 1:1.5).
In various examples, the difunctional ionic group monomer(s) is/are 100% or the non-crosslinking monomer(s) or 1-50% (by weight based on the total weight of the non-crosslinking monomer(s)) (e.g., 10-50% by weight or 20-50% by weight), including all 0.1% by weight values and ranges therebetween.
Use of “dangling” group monomer(s) (which may be referred to a non-crosslinked monomer(s) or non-crosslinking monomer(s)) typically provides a solid phase electrolyte with “dangling” groups. “Dangling” groups may be formed by selecting a skewed stoichiometry or selecting the appropriate conditions to result in a lower conversion (e.g., less than 100% conversion). In various examples, for a 1:1 monomer stoichiometry (ratio of difunctional polyether monomer(s) to multifunctional crosslinking monomer(s)), the conversion may be less than 100%.
A “dangling” group monomer may further comprise one or more anionic group(s) (e.g., one or more anionic group(s) covalently bound to a “dangling” group monomer. Such anionic group(s) and their cation(s) may be referred to as tethered ions.
A reaction can be carried out with various monomer conversion. In various examples, the conversion (e.g., reaction of more or all of the monomer(s) (e.g., difunctional polyether monomer(s), one or more difunctional ionic monomer(s), “dangling” group monomer(s), multifunctional crosslinking monomer(s), or a combination thereof)) of the polymerization is 80% or more, 90% or more, 95% or more, 99% or more, or 100%.
Reactant stoichiometry can vary. Reaction stoichiometry is typically 1:1 to 2:1 (e.g., thiol:ene or thiol:alkyne, respectively), including all 0.1 ratio values and ranges therebetween. Without intending to be bound by any particular theory, it is considered thiol:ene ratios in this range provide desirable conversion. Reactant stoichiometry is typically 1:1 thiol:ene or 2:1 thiol:alkyne to maximize functional group conversion. However, reactant stoichiometry may be skewed to create non-crosslinked “dangling” groups without needing to add a monofunctional monomer.
A reaction mixture may comprise one or more one or more polymerization initiator(s). Various polymerization initiators can be used. Combinations of polymerization initiators may be used. Non-limiting examples of polymerization initiators include photoinitiator(s), thermal initiator(s), redox initiator(s), and the like, and combinations thereof. Suitable initiators described herein. Suitable initiators are also known in the art and/or commercially available. Only a small amount of initiator is typically used (e.g., about 1 mol %).
A reaction may be carried out at various temperatures. In various examples, a reaction is carried out at room temperature or at a temperature of (e.g., heated to a temperature of) of 22 to 90° C., including all 0.1° C. values and ranges therebetween.
A reaction may be carried out for various times. The reaction time may depend on factors such as, for example, initiator/initiation efficiency, temperature, intensity of light (in the case of photochemical reactions with or without a photoinitiator), film thickness, or the like, or a combination thereof. In various examples, reaction times range from seconds (e.g., two seconds) to 24 hours, including all integer second values and ranges therebetween.
A method may comprise exposing the reaction mixture to electromagnetic radiation. Without intending to be bound by any particular theory, it is considered that exposing the reaction mixture to electromagnetic radiation initiates the reaction of at least a portion of the one or more difunctional polyether monomer(s) and one or more multifunctional crosslinking monomer(s) and, optionally, one or more non-crosslinking monomer(s). The exposing can be carried out for various lengths of time. In various examples, the exposing is carried out for 2 seconds to 24 hours, including all integer second values and ranges therebetween.
It may be desirable that at least a portion or all of the electromagnetic radiation wavelength(s) are absorbed by the one or more photosensitizer(s) (e.g., photoinititator(s) and the like). Typically, wavelengths of 200 nm to 450 nm are used.
A reaction may be carried out without an initiator. Radical initiation may be carried out in the absence of a photoinitiator by direct irradiation with light, typically in the UV spectrum. Typical irradiation wavelengths are 200 nm to 450 nm. In various examples, a reaction is carried out without an initiator, by heating the reaction mixture and/or using electromagnetic radiation such as, for example, 254 nm light.
It may be desirable or necessary to remove all or substantially all of the solvent(s) (e.g., in the case of solvents, such as, for example, acyclic carbonates, cyclic carbonates, alkyl nitriles (e.g., succinonitrile and the like, or a combination thereof)) from the solid phase electrolyte. In an example, all or substantially all of the solvent(s) are removed from the solid phase electrolyte prior to assembly of a device.
In various examples, polymerization is carried out in the temperature range of 22° C. to 90° C., including all 0.1° C. values and ranges therebetween, in ambient atmosphere or under an inert atmosphere (e.g., nitrogen, and the like, or a combination of inert gases). Reaction times may vary from a few seconds to 24 hours depending on the initiator efficiency, heat or intensity of light, film thickness, etc.
Stand-alone films may be made. For example, stand-alone films are made by polymerization in a mold where the thickness of the film was defined.
Polymerization can also be carried about directly on an electrode surface (either in an in situ or ex situ method. In various examples, such polymerization is a photochemically or thermally initiated polymerization.
The polymer networks may be made in situ. For example, a polymer network is made in situ using a thermal initiator. A method may be carried out in situ in a device (such as, for example, a battery, a supercapacitor, a fuel cell, or the like) to form a solid phase electrolyte, which may be a gel electrolyte. A method may be carried out to form a solid phase electrolyte on an electrode surface.
In an aspect, the present disclosure provides uses of solid-polymer electrolytes. The solid-polymer electrolytes may be solid-polymer electrolytes of the present disclosure. Non-limiting examples of uses of solid-polymer electrolytes are described herein.
A device may comprise one or more solid-polymer electrolyte(s) of the present disclosure. Non-limiting examples of devices include batteries, supercapacitors, fuel cells, and the like. In the case of a device comprising two or more solid-polymer electrolytes, one or more of the solid-polymer electrolytes may be different (e.g., in terms of one or more compositional feature(s) and/or one or more structural feature(s)) than the other electrolytes or all of the solid-polymer electrolytes may be different (e.g., in terms of one or more compositional feature(s) and/or one or more structural feature(s)). The solid-polymer electrolyte(s) may be formed in situ in the device.
A solid-polymer electrolyte may be formed in situ in a device. A device may comprise a composition that reacts in situ in a device to form a solid-polymer electrolyte. A composition may comprise optionally, one or more difunctional polyether monomer(s), one or more multifunctional crosslinking monomer(s), optionally, one or more difunctional ionic monomer(s) monomer(s), optionally, one or more non-crosslinked (“dangling” group) monomer(s), and, optionally, one or more solvent(s). In various examples, the individual monomers have one or more groups that can react with a group on another monomer to form a cross-linking group. In various examples, the composition comprises at least one difunctional monomer. In various examples, the composition comprises at least one difunctional ionic monomer. In various examples, the composition comprises at least one difunctional monomer and at least one difunctional ionic monomer. In various examples, the composition comprises at least one difunctional monomer and at least one difunctional ionic monomer and at least one non-crosslinking monomer. In various examples, the composition does not comprise a non-crosslinking monomer. Without intending to be bound by any particular theory, it is considered that one or more difunctional polyether monomer(s) have at least two reactive groups (or all the reactive groups) that react with at least two reactive groups (or all the reactive groups) of the one or more multifunctional crosslinking monomer(s) to form at least two crosslinking groups each crosslinking group comprising a thioether group (e.g., a carbon-sulfur bond) and the one or more difunctional polyether monomer(s) groups and one or more multifunctional crosslinking monomer(s) and, optionally, one or more non-crosslinked (“dangling” group) monomer(s) react to form the solid-polymer electrolyte. A composition may comprise one or more polymerization initiator(s), one or more conducting salt(s) (e.g., lithium salt(s), sodium salt(s), potassium salt(s), aluminum salt(s), magnesium salt(s), ammonium salt(s), or the like, or a combination thereof). A composition may further comprise a liquid, which may be a component of a liquid electrolyte.
A device may be a battery. A battery may be an ion-conducting battery. In various examples, a battery also comprises: a cathode; an anode; optionally, a separator, current collector, where the solid-polymer electrolyte, and, if present, the separator, is disposed between the cathode and anode.
Various cathode materials can be used. Suitable cathode materials are known in the art and are commercially available. Non-limiting examples of lithium-containing cathode material include LiCoO2, LiFePO4, Li2MMn3O8, where M is selected from Fe, Co, and combinations thereof, LiMn2O4, LiNiCoAlO2, LiNixMnyCOzO2, where x+y+z=1 (e.g., 0.5:0.3:0.2), and the like, and combinations thereof. Non-limiting examples of sodium-containing cathode materials include Na2V2O5, P2-Na2/3Fe1/2Mn1/2O2, Na3V2(PO4)3, NaMn1/3Co1/3Ni1/3PO4, and Na2/3Fe1/2Mn1/2O2@graphene composite, and the like, and combinations thereof. Non-limiting examples of magnesium-containing cathode materials include doped manganese oxides, and combinations thereof, and the like, and combinations thereof.
Various anode materials can be used. Suitable anode materials are known in the art and are commercially available. Non-limiting examples of lithium-ion conducting anode materials include lithium titanate (Li4Ti5Oi2), and the like, and combinations thereof.
A device may comprise a liquid electrolyte. Non-limiting examples of liquid electrolytes include LiPF6 in EC/DMC, LiTFSI in EC/DMC, and the like.
The following Statements are examples of solid-polymer electrolytes, methods of making solid-polymer electrolytes, and devices of the present disclosure:
and the like), vinylene carbonate (VC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), 1,2-dimethoxyethane (DME), and the like),
where n is 1, 2, or 3 (e.g., diglyme (DEGDME), tetraglyme (TEGDME), and the like), and the like, and combinations thereof.
and/or one or more conducting salt(s) (e.g., metal salt(s), tetraalkylammonium salt(s), and the like, and combinations thereof), the conducting salt(s) individually comprising one or more conducting cation(s) (e.g., metal cation(s), tetraalkyl ammonium ion(s), and the like, and combinations thereof), such as, for example, lithium cation, sodium cation, potassium cation, aluminum cation, magnesium cation, ammonium ion, or the like, or a combination thereof).
alpha amino ketones
phenyl glyoxolates
benzylmethyl ketone, diaryl ketones
aryl diketones
aryl phosphine oxides
3-ketocoumarins, arylalkylketones, benzoin ethers, thioxanthones, quinones, hexaarylbiimidazoyls, oximes, and the like, and combinations thereof,
and the like, and combinations thereof,
and the like, and combinations thereof,
where n is 0 to 250 (e.g., 1 to 250) (e.g., Mx is 44 to 10,000 g/mol), and
alkylthiol groups
and the like) (examples of alkenyl groups include, but are not limited to, alkyl alkenyl groups
alkyl alkynyl groups
acryloyl groups (e.g.,
where R3 is independently H or an alkyl group, and the like), cycloalkenyl alkenyls
and
where A+ is a cation (e.g., M+, such as, for example, Li+, Na+, K+, Mg+, Al+3 (in this case the number of single charged anions in the above examples would triple) and the like, or NR4+, where R is independently a C1 to C6 alkyl group, or the like, or a combination thereof), where
where n is 0 to 20 (e.g., 0, 1, 2, 1 to 10, 1 to 20, or 2 to 20), including all integer values and ranges therebetween, m is 0 to 250 (e.g., 1 to 250), including all integer values and ranges therebetween, and x is H or methyl.
multifunctional trialkyl isocyanuratecrosslinking monomer(s)
multifunctional triazinyl crosslinking monomer(s) (e.g.,
and the like, and combinations thereof.
The multifunctional triazinanyl crosslinking monomer(s), multifunctional 2,4,6-trione triazinanyl crosslinking monomer(s), or multifunctional triazinyl crosslinking monomer(s) may have alkenyls (e.g., allyl groups, which may be allyl ether groups) on one or more N and/or one or more carbons of the triazinanyl or triazine ring.
and combinations thereof,
alkylthiol groups
and the like) (examples of alkenyl groups include, but are not limited to, alkyl alkenyl groups
alkyl alkynyl groups
acryloyl groups (e.g.,
where R3 is independently H or an alkyl group, and the like), cycloalkenyl alkenyls
where n is 0 to 250 (e.g., 1 to 250) (e.g., Mx is 44 to 10,000 g/mol) , including all integer values and ranges therebetween, and R1 is independently chosen from thiol groups and alkenyl groups (examples of thiol groups include, but are not limited to, acylthiol groups
and the like), alkylthiol groups
and the like) (examples of alkenyl groups include, but are not limited to, alkyl alkenyl groups
alkyl alkynyl groups
acryloyl groups (e.g.
where R3 is independently H or an alkyl group, and the like), cycloalkenyl alkenyls
and
where R1 is independently chosen from H and alkyl groups, w is 1-20 (e.g., 1 to 10 or 2 to 20), including all integer values and ranges therebetween), and A+ is a cation (e.g., M+, such as, for example, Li+, Na+, K+, Mg+, Al+3 (in this case the number of single charged anions in the above examples would triple), and the like or N(R)4+, where R is independently a C1 to C6 alkyl group, or the like), and
where R1 is independently chosen from H and alkyl groups, n is 1 to 10, and the like, and combinations thereof.
and the like), vinylene carbonate (VC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), 1,2-dimethoxyethane (DME), and the like),
where n is 1, 2, or 3 (e.g., diglyme (DEGDME), tetraglyme (TEGDME), and the like), and the like, alkyl nitriles (e.g., succinonitrile, acetonitrile, and the like), and the like and combinations thereof, and the like, and combinations thereof.
and the like), vinylene carbonate (VC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), 1,2-dimethoxyethane (DME), and the like),
where n is 1, 2, or 3 (e.g., diglyme (DEGDME), tetraglyme (TEGDME), and the like), and the like, alkyl nitriles (e.g., succinonitrile, acetonitrile, and the like), and the like and combinations thereof.
Non-limiting examples of sodium-containing anode materials include Na2C8H4O4, Na0.66Li0.22Ti0.78O2, and the like, and combinations thereof.
The steps of the method described in the various examples disclosed herein are sufficient to carry out the methods of the present disclosure. Thus, in an example, a method consists essentially of a combination of the steps of the methods disclosed herein. In another example, a method consists of such steps.
The following example is presented to illustrate the present disclosure. The examples are not intended to be limiting in any manner.
This example describes examples of solid phase electrolytes and synthesis and characterization and use of same.
In this Example, lithium electrodeposition was investigated in uniformly porous, nanostructured media formed in cross-linked poly(ethylene oxide) polymer networks enabled by thiol-ene click chemistry. Using galvanostatic strip-plate experiments along with scanning electron microscopy and operando visualization techniques, the effectiveness of these materials in enabling uniform, planar deposition of lithium was critically assessed. The thiol-ene click networks that host a liquid electrolyte in their pores are more effective than their liquid electrolyte or solid polymer network components in regulating Li deposition at both the nucleation and growth phases. It was shown further that compressive interfacial stresses imparted by the networks during electrodeposition may serve to augment surface tension to enable uniform Li electrodeposition. The application of the electrolytes was demonstrated in full-cell battery configurations with desirable long-term stability.
Thiol-ene chemistry was used to cross-link macromonomers based on poly(ethylene oxide) (PEO) to create novel solid-state polymer electrolyte materials with exceptional electrochemical stability when in contact with a Li metal anode. Through simple adjustments of the synthesis conditions, it was shown further that it is possible to manipulate the network pore size over a broad range, allowing precise evaluation of the effectiveness of the materials in preventing dendrite proliferation through in situ galvanostatic visualization experiments. The results show that cross-linked polymer membranes are desirable electrolytes, when used either as dry/solvent-free electrolytes or as a gel host for a liquid electrolyte. Finally, the feasibility of these networks for high-voltage lithium metal batteries was demonstrated for broader applications.
In this Example, cross-linked network films were synthesized using photoinitiated thiol-ene polymerization as depicted in
Lithium-ion transport predominately occurs in the amorphous region of a polymer electrolyte, promoted by the segmental motion of polymer chains. To evaluate the effect of chain length between cross-links on ionic conductivity and electrolyte physical properties, PEGDA macromonomers of different molecular weights were synthesized and cross-linked into networks of varied cross-link density. Thermal properties and ionic conductivities for the different networks are shown in Table 1. Ionic conductivities over a temperature range of −15° C. to 90° C. are reported in
In other words, at high cross-link densities, low segmental motion and a denser network impairs ion transport. However, at low cross-link densities the molecular weight between cross-links is high enough for intermolecular entanglements and crystallization to impede ion transport. Accordingly, because cross-link density and PEO molecular weight are inversely coupled for the networks studied, a maximum in conductivity was observed for networks comprised of PEO macromonomer of Mn near Mc. It is noted that the conductivity maximum was also observed at a similar molecular weight for other cross-linked systems based on PEO and LiTFSI salt, regardless of the cross-linking chemistry utilized. This is consistent with the idea that this molecular weight is a fundamental characteristic of cross-linked PEO networks associated with Mc. For subsequent studies in this Example, the focus was on networks using 3000 g/mol PEO-based macromonomers.
A motivation for using a cross-linked polymer electrolyte is to evaluate the predictions of recent theory that such materials may be able to confine electrodeposition of metals to small length scales proportional to the cross-link density or mesh size of the network. To characterize the average mesh size of the networks, rheological measurements were performed at different temperatures. Dynamic storage (G′) and loss (G″) moduli measured in small strain amplitude (strain=0.1%) oscillatory shear measurements in the linear viscoelastic regime are reported in
The calculated values are in the range 1-5 nm for the three systems, indicating the networks are tightly cross-linked. Alternatively, the measured G″ can be used to obtain an empirical value for the molecular weight between cross-links, Mx, using the relationship:
M
x
=ρRT/G
e (2)
where ρ=ρnetwork≈1.2 g/cm3 and Ge≈2 MPa, 0.9 MPa, and 0.5 MPa at 90° C. for XPE-1k, XPE-3k, and XPE-5k, respectively (see
To evaluate the effectiveness of the cross-linked polymer electrolytes in stabilizing electrodeposition, first performed were galvanostatic strip-plate measurements at 40° C., 60° C., and 90° C. using the solid-state XPE-3k. It is noted that these materials contain no solvent or plasticizer.
The current-overpotential plot (
To overcome transport limitations of the solid XPE electrolytes, the cross-linked polymer networks were soaked in liquid electrolyte to increase their bulk and interfacial ionic conductivities. A liquid electrolyte composed of 1M LiTFSI dissolved in a 1:1 (v:v) mixture of ethylene carbonate (EC) and dimethyl carbonate (DMC) was used in all studies. The cross-linked networks swelled by an average of 40-60% by mass in the liquid electrolyte. The resulting materials obtained after maximum electrolyte uptake were mechanically tough, elastic materials with Ge values comparable to those of the original XPEs (
Electrochemical Impedance Spectroscopy (EIS) measurements indicated that the liquid component in the XPGEs drastically reduced the interfacial resistance at room temperature to values comparable to those of the solid XPEs at 90° C. (
In order to eliminate the effect of thickness difference between XPGE-3k and the Celgard control, additional polarization experiments at 1 mAh/cm2 were performed with glass fiber separators. The glass fiber separators were the same thickness as XPGE-3k (100 μm) and were soaked in the same electrolyte.
To study the morphology of lithium deposits at early stages of deposition, a small capacity of lithium (0.1 mAh/cm2) was deposited on a stainless-steel substrate in cells containing XPGE-3k and were compared to cells containing a Celgard 3501 separator as a control. SEM analysis of the deposits revealed that the average diameter of Li nuclei formed in the XPGE-3k electrolytes were much smaller (0.14 μm in XPGE-3k compared to 0.96 μm in Celgard) and the number density of nuclei correspondingly larger (5.9 nuclei/μm2 versus 0.27 nuclei/μm2) (
In order to determine the cause of the different Li morphologies, the mechanism of Li nucleation was attempted to be described. Metal nucleation at lower areal capacities is characterized by a nucleation overpotential, while the subsequent growth at higher areal capacities is dominated by mass transfer overpotentials.33 A sharp peak in the voltage response marks the nucleation overpotential while the later gradual plateauing of the voltage response to lower voltage indicates the transition to mass transfer overpotentials. In
At least two hypotheses can therefore be proposed to explain the effectiveness of cross-linked polymers in facilitating stable lithium electrodeposition. First, the smaller pore size of the cross-linked polymer, in comparison to Celgard, could amplify the effect of forces such as surface tension that are strongest on small length scales in preventing rapid growth of nuclei. Alternatively, the mechanical stresses produced by the cross-linked polymer membrane in contact with the growing nuclei will exert a local tensile force on the growing nuclei that is analogous to surface tension. This force will augment normal surface tension by an amount proportional to the shear modulus of the polymer network and would produce a planarizing effect on the Li nuclei analogous to what is observed in the experiments.
To evaluate these hypotheses, direct operando visualization experiments were performed at fixed current densities to visualize time-dependent morphology changes at the
Li anode during continuous plating/polarization.
The average electrodeposit thickness and growth rate at 6 mA/cm2 were analyzed using Matlab to gain insight into the evolution of lithium electrodeposition. Multiple points on the propagating front were tracked and averaged to obtain plots of the deposit height and growth rate over time for XPGE-1k, XPGE-3k, XPGE-5k, and a liquid electrolyte (1 M LiTFSI in EC/DMC) (
In all cases, it was observed that Li deposit growth rate decreased before reaching a constant value. It is possible that stress develops in the cross-linked network over time due to lithium deposition, eventually reaching a saturation point, which produces a constant, lower growth rate. To test this idea, a mechanical rheology experiment was designed to model the conditions of the visualization experiment and the deposition process (
In order to compare the model compression experiment to the visualization studies, the strain experienced by the polymer networks during deposition was calculated from the visualization experiments (
Finally, to assess the potential for wider applications of cross-linked polymer gel electrolytes for practical lithium metal batteries, Li∥NCM 622 cells were assembled with high cathode loadings (3 mAh/cm2) and XPGE-3k as the electrolyte. Ether-based electrolytes are known to decompose at high voltages, but can be stabilized by lithium bis(oxalato)borate (LiBOB) salts owing to the formation of a protective cathode-electrolyte interface (CEI).36 To create a stable CEI, the porous cathode was wetted with a LiBOB-containing liquid electrolyte (0.4 M LiBOB, 0.6 M LiTFSI, 0.05 M LiPF6 in 1:1 (v:v) EC/DMC) prior to cell assembly. LiPF6 is included in the formulation to prevent corrosion of the aluminum current-collector used for the cathode. XPGE-3k was used as the bulk electrolyte without modifying its previously described composition. The cycling results showed excellent active material utilization and capacity retention at a moderate rate of C/5 for over 120 cycles (
Experimental Details. All air and water sensitive manipulations were carried out under dry nitrogen conditions in an MBraun Labmaster glovebox or by using standard Schlenk line technique. 1H spectra were collected on a Bruker AV III HD (1H, 500 MHz) spectrometer with a broad band Prodigy cryoprobe and referenced to residual non-deuterated solvent shifts (CHCl3=7.26 ppm). 13C NMR were collected on a Bruker AV III HD (13C, 125 MHz) spectrometer with a broad band Prodigy cryoprobe and referenced to chloroform (δ=77.16 ppm). FT-IR spectra were recorded on a Bruker Tensor II FTIR Spectrometer equipped with an attenuated total reflectance (ATR) accessory.
Atomic force microscopy (AFM) images were measured at the Cornell Energy Systems Institute (CESI) using Cypher ES, Oxford Instruments Asylum Research, Inc. AC tapping mode was selected to collect topography and phase images using an AC160TS-R3 probe (frequency 300 kHz, spring constant 26 N/m, 7 nm tip radius).
Oscillatory shear measurements were performed using a MCR301 (Anton Paar) rheometer at Cornell Energy Systems Institute (CESI) equipped with a 10 mm parallel plate fixture at temperatures ranging from 40 to 90° C. A low strain rate of 0.1% was used for the frequency sweeps to remain in the linear viscoelastic regime.
X-ray Photoelectron Spectroscopy measurements were conducted at the Cornell Center for Materials Research (CCMR) using a Surface Science Instruments SSX-100 with an operating pressure of ˜2×10−9 torr. Monochromatic Al K-α x-rays (1486.6 eV) with beam diameter of 1 mm were used. Photoelectrons were collected at an emission angle of 55° and the electron kinetic energy was determined by a hemispherical analyzer, where a pass energy of 150 V was used for wide survey scans and 50V for high resolution scans. CasaXPS software was used for XPS data analysis with Shelby backgrounds and the spectra were referenced to adventitious C 1 s at 284.5 eV.
Materials. Tetrahydrofuran (THF) was purified over a column of alumina and degassed by three freeze-pump thaw cycles and stored under nitrogen. Poly(ethylene glycol) (Mn 1,000, 3,000, and 4,600 g/mol) (Sigma Aldrich) was dried by azeotroping with toluene at 80° C. under vacuum for 16 h. Sodium hydride (Sigma Aldrich, 90%) and Lithium bis(trifluoromethanesulfonyl)imide (Sigma Aldrich, 99.95% trace metals basis) were stored under nitrogen in a glovebox. Lithium foil was purchased from Alfa Aesar and NCM 811 cathodes were provided by Nohms Inc. Celgard 3501 was used for control samples in electrochemical testing and Glass Fibre Separators were obtained from Fischer Scientific. All other reagents were purchased from commercial sources and used as received unless otherwise noted.
Synthesis of PEG Diallyl Ether (PEGDA). Poly(ethylene glycol)s of Mn 1,000 g/mol, 3,000 g/mol, and 5,000 g/mol were functionalized using the following representative procedure: To a suspension of NaH (1.33 g, 50.1 mmol) in anhydrous THF (50 mL) was added dropwise a solution of PEG (Mn=3,000 g/mol) (50 g, 16.7 mmol) in anhydrous THF (150 mL). The mixture was stirred under N2 at 22° C. for 16 h with an oil bubbler to allow H2 evolution. Allyl bromide (7.2 mL, 83.3 mmol) was then added dropwise over 10 min and the mixture was heated to 50° C. under N2 for 24 h. The solution was quenched with a minimum amount of methanol and the solution was filtered through a pad of celite. The filtrate was concentrated under vacuum and the residue was taken up in DCM (˜250 mL) and washed with 20% NH4OH (2×100 mL), 1 M HCl (2×100 mL), and brine. The organic layer was dried over MgSO4, filtered, and concentrated under vacuum. The oil residue was then precipitated into cold ether (˜500 mL), collected, and dried. Precipitations were repeated as necessary to obtain a white powder (41 g, 80%). 1H NMR (500 MHz, CDCl3) (
Synthesis of Cross-linked Polymer Electrolyte (XPE). PEGDA was mixed with pentaerythritol tetrakis (3-mercaptopropionate) (4T) in a 2:1 molar ratio to maintain a 1:1 stoichiometry between thiol and allyl reactive groups. Lithium bis(trifluoromethanesulfonyl)imide salt was added in the desired EO:Li ratio and the mixture was stirred at 80° C. until homogeneous. The photoinitiator, 2,2-Dimethoxy-2-phenylacetophenone (DMPA), was mixed into the precursor solution at 1 mol % immediately before casting the monomer mixture between silylated glass plates. A 100 μm spacer was used to control the film thickness. The film was cured at 80° C. under 350 nm of UV light for 12 hours to ensure maximum conversion. We note, however, that films cured for 30 minutes showed identical mechanical properties to films cured for longer times (
Synthesis of Cross-linked Polymer Gel Electrolytes (XPGE). PEGDA was mixed with pentaerythritol tetrakis (3-mercaptopropionate) (4T) in a 2:1 molar ratio to maintain a 1:1 stoichiometry between thiol and allyl reactive groups. The mixture was stirred at 80° C. until homogeneous. The photo-initiator, 2,2-Dimethoxy-2-phenylacetophenone (DMPA), was added to the precursor solution at 1 mol % and mixed briefly before film casting. Samples for the lithium deposition visualization studies were cast in a stainless-steel mold (15 mm diameter, 2 mm depth). Samples for full cell battery tests were cast between silylated glass plates at an average thickness of 100 μm. The films were cured at 80° C. under 350 nm of UV light for 16 hours to ensure full conversion. The films were then dried at 80° C. under vacuum for 48 hours. Inside an argon glovebox, the membranes were soaked for 1 hour in an electrolyte solution until equilibrium swelling was achieved. For full cell Li∥NCM 622 tests, the liquid electrolyte component was composed of 0.4 M LiBOB, 0.6 M LiTFSI, 0.05 M LiPF6 in 1:1 (v:v) EC/DMC. For all other experiments utilizing XPGE membranes, the liquid component used was 1 M LiTFSI in 1:1 (v:v) EC/DMC.
Electrochemical Characterization. Ionic conductivity and impedance measurements as a function of temperature were measured at Cornell Energy Systems Institute (CESI) with a Novocontrol N40 broadband spectrometer fitted with a Quarto temperature control system. The coin cells were assembled by sandwiching the electrolyte between two stainless steel electrodes (and lithium as the electrodes for impedance measurements) and sealed in the glovebox to prevent contamination. Galvanostatic strip/plate experiments were performed using coin cells with the electrolyte sandwiched between two lithium electrodes (diameter=6.35 mm). Cyclic Voltammetry measurements were performed using a high scan rate of 0.2 V/s in symmetric cells with small electrodes (2 mm radius) to avoid ohmic drops and polarizations. High temperature measurements were performed by placing the coin cells in a convection oven (VWR). Visualization was performed in a setup previously described. 1 Analysis of dendrite growth was performed using MatLab. Full cell measurements were performed using a high loading NCM cathode (3 mA/cm2 from NOHMS Inc.) and lithium foil as the cathode. At the cathode side, a Celgard 3501 layer was soaked with a small amount of liquid electrolyte with the additives mentioned to wet the porous electrode.
Highly uniform PEG-based networks using thiol-ene chemistry were synthesized in order to study lithium electrodeposition in cross-linked polymer electrolyte networks. Conductivity measurements of the solid polymer networks in this Example indicated a critical molecular weight of PEO chains at which maximum conductivity was achieved. Galvanostatic strip-plate experiments and impedance measurements showed stable solid-state cycling as a result of low interfacial resistance at high temperature. However, investigation into the interplay between lithium-ion diffusion through the network and reaction rate at the electrode interface using cyclic voltammetry suggests that the ratio between diffusion and reaction rate may be an important factor to consider in the design of cross-linked polymer electrolytes.
Soaking the polymer networks in a liquid electrolyte to form XPGE networks improved lithium-ion diffusion and interfacial kinetics. Notably, the XPGE networks showed stable cycling in excess of 150 cycles despite hosting a liquid electrolyte known to decompose at the electrode over time. Optical microscopy in-operando visualization techniques showed the XPGE networks are capable of significant suppression of lithium dendrite growth by enabling controlled, uniform lithium deposition. SEM analysis of the lithium anode surface further revealed that the network architecture enabled small, dense lithium deposits in the initial phase of nucleation. As deposition progressed, the nuclei were found to merge and form planar deposits. Additionally, the effect of cross-link density and subsequently the compressive stresses developed in the networks during electrodeposition were also investigated using rheology. It was found that the compressive stresses in the network play a key role in the suppression and saturation of the growth rate of lithium deposits over time, possibly leading to the observed planar deposits. Finally, the practical applicability of these electrolytes was demonstrated in full cell lithium metal battery configurations with desirable long-term stability over 100 cycles.
aAll films have an EO:Li ratio of 18:1 (r = 0.056); where EO denotes ethylene oxide units in the PEG diallyl ether macromonomer. XPE-nk denotes cross-linked polymer electrolyte using PEGDA macromonomer of n kg/mol.
bNumber average molecular weight (Mn) determined by 1H NMR.
cGlass transition temperature (Tg), melting temperature (Tm), crystallization temperature (Tc), and enthalpy of fusion (ΔHfus) were determined by differential scanning calorimetry (DSC).
dDetermined by dielectric spectroscopy measurements.
eNot detected.
Although the present disclosure has been described with respect to one or more particular embodiment(s) and examples, it will be understood that other embodiments and examples of the present disclosure may be made without departing from the scope of the present disclosure.
This application claims priority to U.S. Provisional Patent Application No. 62/983,159, filed Feb. 28, 2020, the disclosure of which are incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2021/020230 | 3/1/2021 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 62983159 | Feb 2020 | US |
