KR20230007334A - Bifunctional ionic liquids for electrolytes - Google Patents

Abstract

a solid polymer electrolyte comprising a cross-linked ionic liquid (IL) matrix having functional groups capable of interacting with lithium ions; polymerizable PEM formulations containing polymerizable ionic liquid (IL) materials (monomers) having functional groups capable of interacting with lithium ions and reactive polymerizable functional groups capable of cross-linking; an electrolyte prepared from a polymerizable formulation comprising a lithium conductive salt, a plasticizer, a crosslinking agent, and a polymerizable IL component containing at least one functional group capable of interacting with lithium ions and a reactive polymerizable functional group capable of crosslinking; electrochemical cells containing electrolytes incorporating these solid PEMs containing polymerized ionic liquid (IL) materials; and methods thereof are disclosed.

Description

Bifunctional ionic liquids for electrolytes

The present disclosure relates to polymerizable polymer electrolyte material formulations, solid polymer electrolytes, electrochemical cells containing solid polymer electrolytes, and methods thereof.

According to information provided by the US Environmental Protection Agency in 2017, the transport sector alone accounts for 29% of global greenhouse gas emissions. Adoption of electric vehicles worldwide will help reduce these numbers substantially. As the worldwide market for lithium-ion (Li-ion) batteries, which are a common feature in electric and hybrid electric vehicles and household appliances, is growing, batteries with high charge/discharge rates, long lifespan and high energy density are needed. It is important to develop First and foremost, efforts need to focus on making these devices safe under normal and negative conditions. Li-ion batteries have been widely used in most consumer electronic devices since Sony commercialized the first battery in 1991. Electric vehicles (EVs) competed for market dominance in personal vehicle sales in the early 20th century, but the advantages of the internal combustion engine (ICE), namely energy-dense fuel and greater power, led General Motors (GM) to the EV-1 This meant that EV development was sporadic and diffuse, until the 1990s when the One of the key components of an EV is the energy storage system (ESS), and improving battery technology could have a potential impact on the commercialization of EVs and help reduce the demand for fossil fuels. A battery is an expensive component of a vehicle or device, and as such, it is important that the battery lasts the life of the vehicle or device. This means that next-generation Li-ion batteries used in EVs and electronic devices will require significant improvements in all components compared to current state-of-the-art Li-ion technology.

Shuttling of positive and negative ions between cell electrodes is the main function of electrolytes. Historically, investigators have focused on developing battery electrodes, and electrolyte development has been limited. Conventional Li-ion batteries use carbonate-based electrolytes capable of transporting lithium ions, but suffer from high flammability and volatility. Much of the electrolyte research has been directed towards the development of reactive additives on the electrodes to prevent or limit the reaction of the electrolyte with the electrodes. Flame retardant additives have also been investigated, but they have not prevented negative thermal reactions in cells, only limiting the severity and scale of fires.

Recently, room temperature ionic liquids (RTIL) have been extensively studied for their electrochemical properties because they are promising materials for electrolytes in Li-ion batteries. Ionic liquids (ILs) are organic salts with large cations and inorganic anions, with melting points below 100°C. The lattice energy in ionic liquids is reduced due to the bulk cations, and thus the melting point is low. ILs are a viable alternative to conventional electrolytes for lithium batteries because of their negligible vapor pressure, non-flammability, wide electrochemical window, high chemical and thermal stability, and good ionic conductivity.

U.S. Pat. No. 6,727,024 and U.S. Pat. No. 6,395,429 to Kang et al. report the use of lithium salt based solid electrolytes and dialkyl ethers as plasticizers, along with acrylates and other functionalized crosslinking agents. Due to the inherently low ionic conductivity of the crosslinker molecules used in prior art electrolytes, the prior art lacks the incorporation of difunctional polymerizable ionic liquids to improve the ionic conductivity of high-energy Li-ion and lithium-based batteries. .

According to one aspect of the present disclosure, a polymerizable ionic liquid (IL) monomer containing at least one functional group capable of interacting with lithium ions and a reactive polymerizable functional group capable of crosslinking the monomer; lithium ion conducting salts; plasticizer; and a crosslinking agent. A polymerizable polymer electrolyte material (PEM) formulation is provided.

According to another aspect of the present disclosure, a cross-linked ionic liquid (IL) matrix comprising a polymer backbone having a functional group capable of interacting with lithium ions together with a plurality of pendant groups; lithium ion conducting salts; and a plasticizer, wherein a plurality of cation moieties are bonded to one or more of the plurality of pendant groups of the polymer backbone, the cation moieties being nitrogen cation moieties, phosphorus cations. moiety, and a sulfur cation moiety.

According to another aspect of the present disclosure, an electrochemical cell comprising an anode and a cathode spaced apart from each other within a solid polymer electrolyte is provided.

According to another aspect of the present disclosure, as a method for producing a solid polymer electrolyte,

a. form a reaction mixture,

i. A polymerizable ionic liquid (IL) monomer containing a functional group capable of interacting with lithium ions and a reactive polymerizable functional group containing at least one of a nitrogen cation moiety, a phosphorus cation moiety, and a sulfur cation moiety,

ii. lithium ion conductive salt;

iii. plasticizer,

iv. polymerization initiator and

v. forming a reaction mixture, comprising a crosslinking agent;

b. Initiating polymerization in the reaction mixture to form the PEM;

A method of making a solid polymer electrolyte is provided, wherein the bifunctional IL monomer forms part of the core of the polymer structure.

These and other aspects of the present disclosure will become apparent upon review of the following detailed description and appended claims.

1 shows the molecular structures of prior art polymerizable IL monomers (ILA) and polymerizable IL monomers (ILB) and (ILC) according to the present disclosure.
Figure 2 shows the molecular structures of polymerizable IL monomers I-IV synthesized according to the present disclosure.
Figure 3 shows cross-linked solid electrolyte (PEM) design and synthesis.
4 shows a specific example of the ion conduction mechanism in a PEM film synthesized using a polymerizable IL monomer according to the present disclosure.
5 is a photograph showing individual components of a Swagelok cell used to measure the ionic conductivity of a PEM film.
6 shows a Nyquist plot used to calculate the ionic conductivity of a PEM film based on bulk resistance.
7 presents TGA data for PEM films showing good thermal stability at high temperatures.
8 shows the molecular structure of polymerizable IL monomers V-XVI according to the present disclosure.

The disclosed technology relates generally to lithium battery electrolytes. In particular, the present technology relates to non-flammable, non-volatile solid-state electrolytes used for lithium ion transport. The present technology also relates to electrolytes useful in energy storage systems suitable for use in consumer electronics and electric vehicles.

This disclosure describes a non-flammable and non-volatile solid electrolyte that overcomes safety concerns in next-generation lithium-based batteries as well as current state-of-the-art Li-ion batteries. Such technology is based on innovative cross-linked polymerizable ILs that can form solid polymer electrolytes. The resulting ionically conductive polymer electrolyte materials (PEMs), including membranes, films, or blocks, simultaneously overcome the poor thermal electrochemical stability and safety problems that have plagued lithium battery electrolytes for years. They provide a platform for engineering electrolytes with both chemical and mechanical harmonization possibilities that expand the range of cell form factors available for consumer as well as automotive applications. Because of the unique and broad electrochemical stability window of cross-linked PEMs, they can be used to significantly improve the operating temperature range and safety of all lithium-based cells.

The present disclosure relates to a polymerizable ionic liquid (IL) material (monomer) containing at least one functional group capable of interacting with lithium ions and one reactive polymerizable functional group; polymerizable PEM formulations containing polymerizable ionic liquid (IL) materials (monomers); solid polymerized PEMs containing polymerized ionic liquid (IL) materials; and electrolytes incorporating these solid PEMs containing polymerized ionic liquid (IL) materials.

Suitable polymerizable ionic liquid (IL) monomers contain functional groups capable of interacting with lithium ions and reactive polymerizable functional groups capable of cross-linking within the polymer. Phrases that can interact with lithium ions are meant to increase Li ^{+ ion} conjugation in polymer electrolyte materials. Suitable lithium ion interacting functional groups include single bonded carbon-oxygen-carbon structures. Examples include ethers, nitriles, silyls, fluoroalkyls, siloxanes, sulfonates, carbonates, esters, ethylene oxide or combinations thereof. Suitable reactive polymerizable functional groups that can be crosslinked in the polymer contain at least one of a nitrogen cation moiety, a phosphorus cation moiety and a sulfur cation moiety. Such suitable bridging functional groups include vinyl, allyl, acrylate, benzylvinyl or acryloyl groups.

In one embodiment of the present disclosure, a plurality of polymerizable ionic liquids containing a lithium ion conductive salt, a plasticizer, a crosslinking agent, at least one functional group capable of interacting with lithium ions and a reactive polymerizable functional group capable of crosslinking in the polymer A solid polymer electrolyte prepared from a formulation comprising (IL) monomers and a photoinitiator is provided. In one embodiment, the electrical energy storage device comprises a) a lithium ion conducting salt; b) plasticizers; c) cross-linking agents; d) a plurality of polymerizable ionic liquid (IL) monomers containing at least one functional group capable of interacting with lithium ions and reactive polymerizable functional groups capable of crosslinking within the polymer; and e) an electrolyte prepared from a formulation containing a photo-initiator.

In one embodiment, the solid PEM electrolyte includes a polymerized IL matrix having a polymer backbone containing at least one functional group capable of interacting with lithium ions. The polymer backbone has a cationic moiety comprising at least one of a nitrogen cationic moiety, a phosphorus cationic moiety, and a sulfur cationic moiety bridged in the polymer matrix by vinyl, allyl, acrylate, benzylvinyl or acryloyl groups. It has a plurality of pendant groups. The PEM electrolyte further includes a lithium ion conductive salt and a plasticizer.

In one embodiment, the nitrogen cation moiety is selected from the group consisting of imidazolium, ammonium, pyridinium, piperidinium, pyrrolidinium, azepinium and morpholinium moieties.

In one embodiment, the phosphorus cationic moiety is selected from the group consisting of phosphonium moieties.

In one embodiment, the sulfur cation moiety is selected from the group consisting of sulfonium moieties.

In one embodiment, the polymerizable IL monomer is a vinyl or allyl or acrylate imidazolium moiety, a vinyl or allyl or acrylate ammonium moiety, a vinyl or allyl or acrylate pyridinium moiety, a vinyl or allyl or acrylate pipette A lithium moiety, a vinyl or allyl or acrylate pyrrolidinium moiety, a vinyl or allyl or acrylate azepinium moiety, a vinyl or allyl or acrylate morpholinium moiety, a vinyl or allyl or acrylate phosphonium moiety t, vinyl or allyl or acrylate sulfonium moieties.

In one embodiment, preferred polymerizable IL monomers include vinyl imidazolium moieties, vinyl pyrrolidinium, acrylate ammonium moieties, acrylate pyrrolidinium moieties.

According to one embodiment of the present disclosure, the cross-linking of the cross-linked polymeric ionic liquid matrix includes at least one of a nitrogen cation moiety, a phosphorus cation moiety, and a sulfur cation moiety. In one embodiment, the bridge of the cross-linked polymerizable IL is a gemini IL moiety.

In one embodiment, suitable molecular structures of polymerizable IL materials containing functional groups capable of interacting with lithium ions are depicted in FIG. 1 as ILB and ILC. ILA is a comparatively polymerizable IL material that does not contain functional groups (eg, alkyl chains) that can interact with lithium ions.

In one embodiment, the polymerizable IL material containing functional groups capable of interacting with lithium ions is present in the range of 0.1% to 50% by weight of each of the solid PEM electrolyte and polymerizable PEM formulation.

In one embodiment, the lithium ion conductive salt is present in the range of 10% to 50% by weight of each of the solid PEM electrolyte and polymerizable PEM formulation. Suitable lithium ion conductive salts include LiBF ₄ , LiNO ₃ , LiPF ₆ , LiAsF ₆ , lithium bis(trifluoromethylsulfonyl)imide (LiTFSI), lithium bis(pentafluoroethylsulfonyl)imide, lithium trifluoro rhoacetate, LiBoB, LiDFOB, LiPO ₂ F ₂ , or analogs or mixtures thereof.

In one embodiment, the plasticizer capable of dissociating lithium ions is present in the range of 5% to 50% by weight of each of the solid PEM electrolyte and polymerizable PEM formulation. In one embodiment, the plasticizer is a non-polymerizable RTIL. Ionic liquids contain organic cations and inorganic/organic anions, suitable organic cations being N-alkyl-N-alkyl-imidazolium, N-alkyl-N-alkyl-pyrrolidinium, N-alkyl-N-alkyl -pyridinium, N-alkyl-N-alkyl-sulfonium, N-alkyl-N-alkyl-ammonium, or N-alkyl-N-alkyl-piperidinium, and the like, suitable anions being tetrafluoroborates, hexafluorophosphate, bis(trifluoromethylsulfonyl)imide, bis(pentafluoroethylsulfonyl)imide, or trifluoroacetate; and the like.

In one embodiment, the plasticizer is a mono- or di-ether containing ethylene glycol. Suitable examples include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol methyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, or mixtures thereof. include

In one embodiment, a battery comprising an anode and a cathode separated from each other by the solid electrolyte described herein is provided.

In one embodiment, a method of preparing a composite electrolyte that (1) can be crosslinked in a polymer containing a functional group capable of interacting with lithium ions and at least one of a nitrogen cation moiety, a phosphorus cation moiety, and a sulfur cation moiety. and (2) initiating polymerization in the reaction mixture to form a polymeric ionic liquid matrix.

In one embodiment, the polymerization initiator is present in the range of 0.1% to 5% by weight of the polymerizable formulation. In one embodiment, the polymerization is a free radical polymerization reaction. In one embodiment, the reaction is initiated by heat, or by ultraviolet energy or by microwave energy. In one embodiment, the method further comprises adding an initiator to the reaction mixture. In one embodiment, polymerization is initiated by ultraviolet energy by using 2-hydroxy-2-methylpropiophenone as a photo-initiator.

Polymerizable ionic liquids have previously been investigated for use as electrolytes. However, due to the decrease in the number of mobile ions and the significant increase in Tg, such an approach of polymerizing conventional ionic liquid monomers has been found to significantly reduce the ionic conductivity. According to the present disclosure, a functional group capable of interacting with lithium ions has been introduced into the bifunctional polymerizable IL monomer structure to increase the ionic conductivity of the polymeric material. Such linkages in the polymer backbone lead to increased Li ⁺ ion conjugation and, therefore, faster transport of ions. Accordingly, the present bifunctional IL monomers provide IL-based PEMs with higher lithium transport rates and improved thermal stability.

Polymerizable ILs are a class of functional polymers useful in a variety of applications. The repeating units of these polymers contain electrolyte groups (cationic or anionic). The ionic conductivity of ILs depends on several factors: the chemical nature of the polymer backbone, the nature of the ions, and the glass transition temperature (Tg). In contrast to high ionic conductivity and high thermal stability, this monomeric IL provides a high Li ^{+ ion} transference number. The high Li ⁺ ion transport rate is a result of the cations being anchored to the polymer backbone and thereby not participating in ionic conduction. For energy storage applications, film type, eg solid polymer, ionically conductive materials are preferred over liquid electrolytes. A polymerizable group may be appended to the ionic liquid component. Compared to liquid electrolytes, solid polymers are lighter in weight and more easily processed, handled and packaged.

Electrolytes for lithium ion batteries with improved ionic conductivity, thermal and mechanical stability are described. Such electrolytes include polymerizable IL materials that can be cast or formed into a variety of shapes, such as films, membranes, and blocks. Polymeric ILs are formed from the crosslinking of polymerizable IL monomers, and contain a backbone (which may optionally contain ionic liquid moieties) and pendant ionic liquid groups (shown as paired positively and negatively charged particles). do. Embodiments of ionic liquid PEMs include bifunctional ionic liquid crosslinks (crosslinkable gemini ionic liquids) that provide mechanical stability to the film and further aid in the ionic conductivity of the composite.

IL-based hybrid PEMs exhibiting high ionic conductivity, broad electrochemical stability and high thermal stability for applications in EVs or PHEVs are disclosed. These electrolytes can be incorporated into Li-metal batteries, Li-sulfur batteries and Li-ion batteries with a high voltage cathode. A library of alternative, largely untapped materials, with a wide range of anionic and cationic chemistries that can be tailored to complement specific combinations of electrode chemistries or combined to create well-designed ILs, can also address cell safety concerns. library) is provided.

Shaplov et al., in their review (Recent Advances in Innovative Polymer Electrolytes based on Poly (ionicliquid)s, 2015), used a poly(ion gel) to synthesize an ionic gel with an ionic conductivity of 0.1 mS/cm at 30 °C. reported the use of allyldimethylammonium) bis(trifluoromethanesulfonyl) imide (TFSI), N-butyl-N-methylpyrrolidinium TFSI ionic liquid and LiTFSI salt. Another paper by Porcarelli et al. (Design of ionic liquid like monomers towards easy-accessible single-ion conducting polymer electrolytes, 2018) showed ionic maximums of 1.9x10 ^-6 and 2x10 ^-5 S.cm ^-1 at 25 °C and 70 °C, respectively. Lithium 3-[4-(2-(methacryloyloxy)ethoxy)-4oxobutanoyl)oxy)propylsulfonyl]-1-(trifluoromethylsulfonyl)imide and poly( reported a copolymer electrolyte based on ethylene glycol) methyl ether methacrylate. All patents, patent applications and publications cited herein are hereby incorporated by reference in their entirety in their entirety to set forth the disclosure of the technology as known to those skilled in the art as of the disclosure date set forth herein. Bifunctional polymerizable IL monomers are ionic liquids incorporating one or more polymerizable units. In ionic liquid monomers, polymerizable features can be located on the cation phase, or on the anion, or on both the cation and anion.

The bifunctionality of ILs is due to a) reactive end groups that can polymerize, and b) functional groups that can interact with the lithium ions of the lithium conducting salt. Suitable functional groups capable of interacting with lithium ions are selected from ethers, nitriles, silyls, fluoroalkyls, siloxanes, sulfonates, carbonates, esters or combinations thereof. Thus, commercial crosslinkers can be partially or completely replaced with bifunctional ILs to create polymer electrolytes with improved ionic conductivity without compromising mechanical stability.

Examples of IL monomers include nitrogen having a nitrogen cation selected from the group including, but not limited to, imidazolium, ammonium, pyridinium, piperidinium, pyrrolidinium, azepinium, and morpholinium nitrogen cation moieties. Contains a cationic moiety. These groups can be functionalized with side groups that can polymerize. Polymerizable groups include vinyl, allyl, acrylate, benzylvinyl and acryloyl groups. These reactive groups can undergo free radical, thermal, ultraviolet or microwave-initiated polymerization to incorporate the monomeric IL into the polymer. 1 shows polymerizable IL monomers ILB and ILC used in Examples for producing PEM films, each incorporating a functional group capable of interacting with lithium ions and a reactive polymerizable functional group capable of crosslinking the monomer into the monomer structure. Compared to the molecular structure of ILA, the prior art polymerizable IL monomer lacking functional groups capable of interacting with lithium ions is shown. 2 shows the molecular structures of suitable polymerizable IL monomers I-IV, each containing a functional group capable of interacting with lithium ions and a reactive polymerizable functional group capable of crosslinking the monomer.

For example, using ILs comprising phosphonium and sulfonium cationic moieties, as well as imidazolium, ammonium, pyridinium, piperidinium, pyrrolidinium, azepinium, and morpholinium nitrogen cationic moieties. Variations can also be used.

In one or more embodiments, classes of vinyl functionalized polymerizable imidazolium (Im), pyrrolidinium (Pyr) and piperidinium (Pip) cation-based monomer ILs are suitable for use as ionic polymer monomers. . A vinyl monomer ionic liquid with bis(trifluoromethylsulfonyl)imide (TFSI) as a counter ion can be synthesized.

cross-linking agent

The composite electrolyte also includes a crosslinking agent and can be crosslinked with the polymerizable ionic liquid (IL) monomers of the present disclosure, helping to improve mechanical strength. The crosslinking agent serves to dictate the flexibility of the membrane. The crosslinker can be a conventional bifunctional molecule (IL monomer) or it can be an ionic liquid capable of polymerizing itself. The bifunctional nature of the crosslinker (typical IL monomers) creates bridges between polymer chains; Crosslinkers can also be incorporated into the growing polymer chain. Common crosslinkers include moieties with two or more vinyl features, such as divinyl benzene, dimethacrylate and diacrylate. Upon reacting with the IL monomers, the crosslinkable ionic liquid can form a bridge between the two polymer backbones, or it can become integrated into the polymer backbone, increasing the ionic conductivity of the polymer itself. This is shown in Figure 3, where the crosslinker and monomeric IL each have an ether group that allows for faster Li ⁺ ion transport.

8 shows molecular structures of polymerizable IL monomers V-XVI, each containing a functional group capable of interacting with lithium ions and a reactive polymerizable functional group capable of crosslinking within the polymer. Figure 8 shows a vinyl pyrrolidinium cation having an ether oxygen functional moiety (monomer V), a vinyl piperidinium cation having an ether oxygen functional moiety (monomer VI), and a styrene pyrrolidinium having a nitrile functional moiety. cation (monomer VII), vinyl ammonium cation with trimethyl silyl functional moiety (monomer VIII), vinyl piperidinium cation with trimethyl silyl functional moiety (monomer IX), vinyl phosphonium with nitrile functional moiety cation (monomer X), vinyl sulfonium cation with nitrile functional moiety (monomer XI), vinyl phosphonium cation with trimethyl silyl functional moiety (monomer XII), vinyl sulfonium with trimethyl silyl functional moiety cation (monomer XIII), vinyl pyrrolidinium cation with carbonyl functional moiety (monomer XIV), vinyl ammonium cation with carbonyl functional moiety (monomer XV), acrylate with ether oxygen functional moiety A variety of suitable difunctional polymerizable ionic liquid (IL) monomers containing ammonium cations (monomer XVI) are shown.

Different Types of Acrylate Crosslinkers

The present disclosure will be further explained with reference to specific examples below. It will be understood that these examples are given for illustrative purposes and are not meant to limit the disclosure or the claims below.

Example A - PEM films of Comparative Examples (CE) 1, CE 2, CE 3 and Example 1 were prepared from formulations containing a lithium conductive salt, monomeric IL, a plasticizer and a crosslinker and subjected to UV radiation using a photoinitiator. was polymerized by Crosslinkers contribute to mechanical strength, while plasticizers help dissociate salts, increasing ionic conductivity. Due to its bifunctional nature, the monomeric IL provides a balance between the ionic conductivity and mechanical properties of the PEM film. The individual components of the PEM film are mixed using a centrifugal mixer to create a highly viscous polymer gel. The viscous polymer gel is drop-casted onto a glass plate and the plate is passed under UV light to create a PEM film with a thickness of 50 μm as shown in FIG. 4 . Figure 4 illustrates the ionic conduction mechanism in PEM films synthesized using polymerizable IL monomers. The degree of crosslinking can be adjusted by varying the UV light exposure time and intensity.

Table A - Electrolyte composition

Example B - Synthesis of Im(vinyl)methylethyl-ether-TFSI (ILB)

quaternization reaction

In a 20 mL vial equipped with a magnetic stir bar, 1-vinylimidazole was added. While stirring at room temperature (RT), 2-bromoethyl methyl ether was added. No fever was observed. The reaction was monitored for starting vinylimidazole by TLC (silica gel 50% EtOAc/DCM). Unreacted vinylimidazole was present in much smaller proportions compared to product that did not migrate from the origin. The amber mixture was stirred at RT for 96 hours and a viscous amber oil formed. Yield: amber oil, 5.0 g (>99%).

Metathesis

To the 20 mL vial containing the dibromide from Step 1, DI water (20 mL) was added, and to the solution, lithium bis(trifluoromethylsulfonyl)imide dissolved in DI water (10 mL) was added. added. A turbid precipitate formed immediately, after which an amber liquid layer was separated from the water. The mixture was stirred at RT for 1 hour. The water layer was decanted, DCM (10 mL) was added and the whole mixture was poured into a separatory funnel. The organic layer was washed with DI water (2 x 10 mL), separated, dried over MgSO ₄ and the solvent stripped by rotary evaporation. Yield: Pale amber oil, 7.8 g (84%).

FTIR: 3151, 1346, 1176, 1051 cm ^-1 .

H ⁺ NMR: (CDC1 ₃ ) δ ppm 8.95 (s, 1H), 7.59 (s, 1H), 7.52 (s, 1H), 7.13 (q, 1H), 5.77 (dd, 1H), 5.45 (dd, 1H) ), 4.41(t, 2H), 3.74(t, 2H), 3.37(s, 3H). F ¹⁹ NMR: (CDC1 ₃ ) δ ppm -79.03(s).

Example C - Synthesis of [Im(vinyl)]2-triethyleneglycol-TFSI (ILC)

conversion to dibromide

To a 100 mL 3-neck flask equipped with a magnetic stir bar, water-cooled condenser, N ₂ inlet and thermocouple, triethylene glycol and DCM (30 mL) were added. The mixture was cooled to 2° C. in an ice/salt bath. While stirring at 2° C., phosphorus tribromide was added dropwise by syringe, and a maximum exotherm to 11° C. was observed. The mixture was slowly returned to RT and stirred for 72 hours. The light blue solution was quenched dropwise until DI water (10 mL) could be added. The mixture was poured into a separatory funnel. The organic phase was extracted with DCM, separated, dried over MgSO ₄ and the solvent was stripped by rotary evaporation. Yield: colorless oil, 6.5 g, (71%).

Quaternization reaction

To 100 mL RB containing the mixture from step A, 1-vinylimidazole was added. No exotherm was observed and the mixture was stirred for 7 days at RT under neat conditions. The mixture became a pale white solid. The solid was slurried in DCM (30 mL) and collected by vacuum filtration. Unreacted starting material and yellow color were removed from the mother liquor. Yield: 8.8 g (81%) as a pale white solid.

Metathesis

In a 100 mL bottle equipped with a magnetic stir bar, dissolve the bromide from step 1 in DI water (20 mL) and combine with a solution of lithium bis(trifluoromethylsulfonyl)imide in 20 mL DI water. did A turbid precipitate formed quickly and a pale yellow oil was deposited on the bottom. The mixture was stirred at RT for 2 h. The water layer was decanted, DCM (20 mL) was added and the whole mixture was poured into a separatory funnel. The organic layer was washed with DI water (2 x 10 mL), separated, dried over MgSO ₄ and the solvent stripped by rotary evaporation. Yield: pale yellow oil, 14.8 g (90%).

FTIR: 3151, 1347, 1176, 1050 cm ^-1 .

H ⁺ NMR: (DMSO-d6) δ ppm 9.40 (s, 2H), 8.18 (t, 2H), 7.84 (t, 2H), 7.30 (q, 2H), 5.95 (dd, 2H), 5.43 (dd, 2H), 4.36(t, 4H), 3.77(t, 4H), 3.56(s, 4H). F ¹⁹ NMR: (CDC13) δ ppm - 78.75(s).

The ionic conductivity is calculated based on the buck resistance of the PEM film obtained from the Nyquist plot using the equation below. The disclosed film was sandwiched between the upper and lower plungers in a Swagelok cell and hermetically sealed the cell for better contact than a coin cell, reducing interfacial resistance. 5 illustrates photographs of individual components of a Swagelok cell used to measure the ionic conductivity of a PEM film.

In the above equation, σ is the ionic conductivity calculated using the thickness (t) and area (A) of the PEM film, and R is the bulk resistance obtained from the Nyquist plot.

Table B - Ion conductivity data at different temperatures:

Ionic conductivity data for PEM films are reported over a temperature range of 25 to 45 °C, which is considered standard operating temperature conditions for lithium-based cells in various applications. Without any plasticizer in the CE 1 film, low ionic conductivity values of less than 0.05 mS/cm at room temperature can be observed. These films have higher crosslinker loadings than films containing ILAs in which the monomeric ILs do not have EO groups in their molecular structure, resulting in low conductivity PEMs. Increasing the Li ⁺ ion conducting salt and optimizing the crosslinker concentration increases the ionic conductivity in the CE 3 film compared to the CE 2 film. As shown in Figure 1, ILB and ILC have EO groups attached to mono-vinyl imidazole and di-vinyl imidazole moieties, respectively. This leads to better Li ⁺ ion conjugation with oxygen in the IL, leading to faster ion migration as shown in FIG. 3 . Example 1 PEM was further optimized using a triacrylate crosslinker B with 3 reactive sites, leading to a more crosslinked PEM film, thus only 10% by weight was required in the formulation. Ionic conductivity values are calculated using a Nyquist plot, which can be seen in FIG. 6, and a reduced impedance (resistance = R) can be observed for the Example 1 film compared to the CE 2 film. 6 shows a Nyquist plot used to calculate the ionic conductivity of a PEM film based on its bulk resistivity. Thus, an increase in room temperature (25° C.) ionic conductivity from 0.33 mS.cm ⁻¹ in CE 3 PEM to 0.82 mS.cm ⁻¹ in Example 1 PEM can be observed (Table B). It is important to note that these are solid PEM films without any liquid or gel component and can achieve high ionic conductivity values at room temperature.

Conventional liquid electrolytes contain flammable carbonate co-solvents with very poor thermal stability, and therefore Li-ion cells containing these electrolytes suffer from stability problems. To study the thermal stability of monomeric IL containing PEM films, we performed a thermogravimetric analysis (TGA). Scans were performed over a temperature range from 20°C to 500°C at a ramp rate of 5°C/min.

7 shows a plot of TGA data for the CE 2 and CE 3 PEM films compared to the Example 1 PEM film showing good thermal stability at high temperatures. In addition to CE 2 and CE 3, the Example 1 PEM film has excellent thermal stability well above 250° C., and thus can improve the safety of lithium-based batteries. The use of PEMs according to the present disclosure in lithium-based cells will enable safer operation over a wide temperature range.

Example D - Synthesis of Im(vinyl)-diethyleneglycol-monoethyl-ether-TFSI (monomer IL I)

conversion to boromide

To a 100 mL 3-neck flask equipped with a magnetic stir bar, water-cooled condenser, N ₂ inlet and thermocouple, diethylene glycol-monoethyl-ether and DCM (30 mL) were added. The mixture was cooled to 2° C. in an ice/salt bath. While stirring at 2° C., phosphorus tribromide was added dropwise by syringe, and a maximum exotherm to 9° C. was observed. The mixture was slowly returned to RT and stirred for 18 hours. The light blue solution was quenched dropwise until DI water (10 mL) could be added. The mixture was poured into a separatory funnel. The organic phase was extracted with DCM, separated, dried over MgSO ₄ and the solvent was stripped by rotary evaporation. Yield: colorless oil, 5.1 g, (70%).

quaternization reaction

To the 20 mL vial containing the mixture from step A, 1-vinylimidazole was added. No exotherm was observed and the mixture was stirred at RT under neat conditions. The reaction was monitored by TLC (silica gel, 50% EtOAc/DCM). Unreacted vinylimidazole was present in much smaller proportions compared to product that did not migrate from the origin. The amber mixture was stirred at RT for 9 days and a viscous light amber oil was formed. Yield: Pale amber oil, 7.5 g (>99%).

Metathesis

In a 50 mL bottle equipped with a magnetic stir bar, dissolve the bromide from step 1 in DI water (20 mL) and combine with a solution of lithium bis(trifluoromethylsulfonyl)imide in 20 mL DI water. did A turbid precipitate formed quickly and a pale yellow oil was deposited on the bottom. The mixture was stirred at RT for 2 h. The water layer was decanted, DCM (20 mL) was added and the whole mixture was poured into a separatory funnel. The organic layer was washed with DI water (2 x 10 mL), separated, dried over MgSO ₄ and the solvent stripped by rotary evaporation. Yield: pale yellow oil, 10.2 g (80%).

FTIR: 3151, 1347, 1177, 1051 cm ^-1 .

H ⁺ NMR: (CDC13) δ ppm 9.03 (s, 1H), 7.63 (t, 1H), 7.58 (t, 1H), 7.10 (q, 1H), 5.78 (dd, 1H), 5.45 (dd, 1H) , 4.43(t, 2H), 3.86(t, 2H), 3.65(t, 2H), 3.58(t, 2H), 3.51(q, 2H), 1.19(t, 3H). F ¹⁹ NMR: (CDC13) δ ppm -79.01(s).

Example E - Synthesis of Im(vinyl)(2HImTEOS)-diethylether-TFSI (monomer IL II)

quaternization reaction

In a 20 mL vial equipped with a magnetic stir bar, N-(3-triethoxysilylpropyl)-4,5-dihydroimidazole, colorless oil (pot, 135° C.; p, 0.25) distilled under vacuum. -0.llmmHg; steam, 96-109° C.) and 1-vinylimidazole and DCM (5 mL) were added. While stirring at RT, bis(2-bromoethyl)ether was added to the mixture. No fever was observed. The reaction was monitored for starting vinylimidazole by TLC (silica gel 50% EtOAc/DCM). Unreacted vinylimidazole was present in much smaller proportions compared to the product that did not migrate from the source. The amber mixture was stirred at RT for 5 days and a highly viscous amber gel was formed. Yield: viscous amber gel, 3.2 g (>99%).

Metathesis

To the 20 mL vial containing the dibromide from Step 1, DI water (20 mL) was added, and to the solution, lithium bis(trifluoromethylsulfonyl)imide dissolved in DI water (10 mL) was added. added. A cloudy precipitate formed immediately, after which a pale yellow oily layer was separated from the water. The mixture was stirred at RT for 1 hour. The water layer was decanted, DCM (10 mL) was added and the whole mixture was poured into a separatory funnel. The organic layer was washed with DI water (2 x 10 mL), separated, dried over MgSO ₄ and the solvent stripped by rotary evaporation. Yield: amber oil, 4.2 g (79%).

FTIR: 2977, 1654, 1179, 1051 cm ^-1 .

H ⁺ NMR: (CDC13) δ ppm 9.35 (s, 2H), 8.15 (s, 2H), 7.81 (s, 2H), 7.26 (q, 2H), 5.93 (dd, 2H), 5.43 (d, 2H) , 4.38 (m, 4H), 3.81 (m, 4H). F ¹⁹ NMR: (CDC13) δ ppm -78.88(s), -79.30(s).

Example F - Synthesis of Im(vinyl)propyl-TMOS-TFSI (monomer IL III)

Quaternization reaction

In a 20 mL vial equipped with a magnetic stir bar, 1-vinylimidazole was added. While stirring at RT, (3-iodopropyl)trimethoxysilane was added. No fever was observed. The reaction was monitored for starting vinylimidazole by TLC (silica gel 50% EtOAc/DCM). Unreacted vinylimidazole was present in much smaller proportions compared to the product that did not migrate from the source. The amber mixture was stirred at RT for 4 days and a viscous amber oil was formed. Yield: amber oil, 4.1 g (>99%).

Metathesis

To the 20 mL vial containing the dibromide from Step 1, DI water (20 mL) was added, and to the solution, lithium bis(trifluoromethylsulfonyl)imide dissolved in DI water (10 mL) was added. added. A turbid precipitate formed immediately, after which an amber liquid layer was separated from the water. The mixture was stirred at RT for 1 hour. The water layer was decanted, DCM (10 mL) was added and the whole mixture was poured into a separatory funnel. The organic layer was washed with DI water (2 x 10 mL), separated, dried over MgSO ₄ and the solvent stripped by rotary evaporation. Yield: Pale amber oil, 5.4 g (95%).

FTIR: 2948, 1348, 1178, 1051 cm ^-1 .

H ⁺ NMR: (CDC13) δ ppm 9.03 (s, 1H), 7.62 (t, 1H), 7.43 (t, 1H), 7.15 (q, 1H), 5.79 (dd, 1H), 5.44 (dd, 1H) , 4.25(t, 2H), 3.57(s, 9H), 2.01(q, 2H), 0.63(t, 2H). F ¹⁹ NMR: (CDC13) δ ppm -79.01(s).

Example G - Synthesis of Im(vinyl)methylbutyrate-TFSI (monomer IL IV)

Quaternization reaction

To a 20 mL vial equipped with a magnetic stir bar, methyl-4-bromobutyrate and 1-vinylimidazole were added. No fever was observed. The amber mixture was stirred at RT for 7 days and a highly viscous amber gel was formed. Yield: viscous amber gel, 5.8 g (>99%).

Metathesis

To the 20 mL vial containing the dibromide from Step 1, DI water (20 mL) was added, and to the solution, lithium bis(trifluoromethylsulfonyl)imide dissolved in DI water (10 mL) was added. added. A cloudy precipitate formed immediately, after which a pale yellow oily layer was separated from the water. The mixture was stirred at RT for 1 hour. The water layer was decanted, DCM (10 mL) was added (only partially soluble) and the whole mixture was poured into a separatory funnel. The organic layer was washed with DI water (2 x 10 mL), separated, dried over MgSO ₄ and the solvent stripped by rotary evaporation. Yield: pale yellow oil, 9.3 g (93%).

FTIR: 3149, 1730, 1347, 1174 cm ^-1 .

H ⁺ NMR: (CDC13) δ ppm 9.06 (s, 1H), 7.62 (s, 1H), 7.49 (s, 1H), 7.13 (q, 1H), 5.79 (dd, 1H), 5.46 (d, 1H) , 4.34(t, 2H), ), 3.68(s, 3H) ), 2.44(t, 2H), 2.22(t, 2H). F ¹⁹ NMR: (CDC13) δ ppm -78.99(s).

Although various embodiments have been shown and described in detail herein, various modifications, additions, and substitutions may be made to those skilled in the art without departing from the spirit of the present disclosure, and accordingly they are defined in the claims below. It will be apparent that it is considered to be within the scope of this disclosure as such.

Claims (20)

As a polymerizable polymer electrolyte material (PEM) formulation,
a polymerizable ionic liquid (IL) monomer containing a functional group capable of interacting with lithium ions and a reactive polymerizable functional group capable of being crosslinked;
lithium ion conducting salts;
plasticizer; and
A polymerizable polymer electrolyte material (PEM) formulation comprising a crosslinking agent. According to claim 1,
A polymerizable polymer electrolyte material (PEM) formulation comprising a single-bonded carbon-oxygen-carbon structure in which functional groups capable of interacting with lithium ions. According to claim 1,
A polymerizable polymer electrolyte material (PEM) formulation wherein the functional groups capable of interacting with lithium ions are selected from ethers, nitriles, silyls, fluoroalkyls, siloxanes, sulfonates, carbonates, esters, ethylene oxides, or combinations thereof. simulation. According to claim 1,
A polymerizable polymer electrolyte material (PEM) formulation wherein the reactive polymerizable functional group capable of crosslinking contains a group selected from vinyl, allyl, acrylate, benzylvinyl and acryloyl. According to claim 1,
A polymerizable polymer electrolyte material (PEM) formulation wherein the crosslinkable reactive polymerizable functional group contains at least one of a nitrogen cation moiety, a phosphorus cation moiety, and a sulfur cation moiety. According to claim 5,
A polymerizable polymer electrolyte material (PEM) formulation wherein the nitrogen cation moiety is selected from the group consisting of imidazolium, ammonium, pyridinium, piperidinium, pyrrolidinium, azepinium, and morpholinium moieties. According to claim 5,
A polymerizable polymer electrolyte material (PEM) formulation wherein the sulfur cationic moiety is selected from the group consisting of sulfonium moieties. According to claim 5,
A polymerizable polymer electrolyte material (PEM) formulation wherein the phosphorus cationic moiety is selected from the group consisting of phosphonium moieties. According to claim 1,
A polymerizable polymer electrolyte material (PEM) formulation wherein the lithium ion conductive salt is present in a range of 10% to 50% by weight of the formulation. According to claim 1,
A polymerizable polymer electrolyte material (PEM) formulation wherein the plasticizer is present in the range of 5% to 50% by weight of the formulation. According to claim 9,
A polymerizable polymer electrolyte material (PEM) formulation wherein the plasticizer is a room temperature ionic liquid (RTIL). According to claim 1,
A polymerizable polymer electrolyte material (PEM) formulation wherein the polymerizable ionic liquid (IL) monomer is present in a range from 0.1% to 50% by weight of the formulation. According to claim 1,
A polymerizable polymer electrolyte material (PEM) formulation wherein the crosslinker is present in a range of 10% to 50% by weight of the formulation. According to claim 1,
A polymerizable polymer electrolyte material (PEM) formulation, wherein the crosslinker comprises at least one of mono-, di- and tri-acrylates and mono-, di- and tri-methacrylates. According to claim 1,
A polymerizable polymer electrolyte material (PEM) formulation, further comprising a polymerization initiator in the range of 0.1% to 5% by weight of the formulation. As a solid polymer electrolyte,
lithium ion conducting salts;
plasticizer; and
A cross-linked ionic liquid (IL) matrix comprising a polymer backbone having a plurality of pendant groups and having a functional group capable of interacting with lithium ions;
A solid polymer electrolyte, wherein a plurality of cationic moieties are bonded to one or more of the plurality of pendant groups of the polymer backbone, and wherein the cationic moiety is at least one of a nitrogen cation moiety, a phosphorus cation moiety, and a sulfur cation moiety. According to claim 16,
A solid polymer electrolyte wherein the matrix comprises a bifunctional ionic liquid crosslink. 17. An electrochemical cell comprising an anode and a cathode spaced from each other in the electrolyte of claim 16. As a method for producing a solid polymer electrolyte,
a. form a reaction mixture,
i. A polymerizable ion containing at least one functional group capable of interacting with lithium ions and a reactive polymerizable functional group capable of crosslinking monomers containing at least one of a nitrogen cation moiety, a phosphorus cation moiety and a sulfur cation moiety. sex liquid (IL) monomer,
ii. lithium ion conductive salt;
iii. plasticizer,
iv. polymerization initiator and
v. forming a reaction mixture, comprising a crosslinking agent;
b. Initiating polymerization in the reaction mixture to form a solid PEM;
A method of making a solid polymer electrolyte wherein an ionic liquid (IL) monomer forms part of the polymer core of the PEM. According to claim 19,
A method wherein the polymerization reaction is initiated by a source of energy selected from the group consisting of ultraviolet light energy, heat, electron bombardment, and microwave energy.

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