Electrolytes for targeted ion transport

Abstract

The present invention provides zwitterionic plastic crystal (ZIPC) compounds in unimolecular form, comprising: at least one positively charged functional group carrying at least one positive charge, and at least one negatively charged functional group carrying at least one negative charge, wherein the positively charged functional group and the negatively charged functional group are covalently linked together in the molecule and the net charge of the zwitterionic compound is zero, and wherein the compound exhibits evidence of molecular disorder in the solid state.

Description

Technical Field

[0001] The present invention relates to a plastic crystalline compound having excellent target ion conducting ability and useful in various applications where rapid target ion conduction is desired, for example, as an electrolyte. Background of the Invention

[0003] Plastic crystals are solids with a long-range, ordered crystal structure and short-range disorder originating from the rotation or disorientation of individual molecules / ions within the ordered lattice. Short-range molecular rearrangements lead to the ability to deform under an applied load (i.e., plasticity) and to enhanced diffusivity of secondary species within the plastic crystal lattice. Plastic crystal electrolytes can be classified as fast ion conductors, in which the primary / target ion (e.g., Li for lithium batteries) is the primary / target ion. + Or for dye-sensitized solar cells, I - / I3 - ) moves rapidly against a background of a relatively static substrate.

[0004] Recently, the applicability of OIPC as a novel solid-state ion conductor in Li batteries, dye-sensitized solar cells, fuel cells, and Na batteries has been demonstrated. This is achieved by doping the OIPC with appropriate cations, such as adding Li salts for their application in Li batteries, or adding acids or bases for fuel cells. In addition, aprotic OIPCs provide good thermal and electrochemical stability, and due to their negligible volatility, they significantly improve safety relative to current electrolytes based on molecular solvents. Organic ion plastic crystals (OIPCs) are structurally disordered salts that can exhibit soft, plastic mechanical properties and significant ionic conductivity. When OIPC is used as a matrix and a second component is introduced (e.g., an acid / base for a fuel cell or a Li or Na salt for a Li / Na battery) into the OIPC matrix and used as a solid electrolyte in an electrochemical device, the structural disorder within the OIPC promotes rapid target ion conduction. However, it is believed that their inherent structure (i.e., separated cations and anions) allows for the migration of undesirable matrix OIPC ions. In an ideal electrolyte material, only target ions (eg, Li, Na, H) would migrate.

[0005] However, the target ion transport through the OIPC is still insufficient and ultimately limits the achievable power output of the device. In fact, low transference numbers (the fraction of charge carried by the active species) such as t Li+ Often < 0.2. This is due to the presence of other mobile species carrying charge, including OIPC cations and anions and lithium salt counterions. For the ideal transference number (t Li+ = 1), only Li ions should move through the electrolyte at any appreciable rate.

[0006] While zwitterionic liquids and even zwitterionic liquid crystals are known, in some rare cases a combination of zwitterionic liquid crystals with LiNTf2 and propylene carbonate can be used as a liquid electrolyte, leakage from the device and the vapor pressure and flammability of this combination are problematic.

[0007] Organic zwitterions in electrochemistry have utilized sulfonate-based structures because these are relatively easy to synthesize in a single step via a combination of sulfone and methylpyrrolidine. However, these sulfonate zwitterions are crystalline solids that show no evidence of plasticity and are therefore unsuitable as standalone electrolyte matrix materials because they lack the soft mechanical properties required for battery cells. Therefore, there is a continuing need for new electrolytes that at least partially address one or more of the aforementioned shortcomings or provide a viable alternative.

[0008] Ohno et al. (Phys.Chem.Chem.Phys., 2018, 20, 10978) described that below its T m An alkyl-substituted imidazolium zwitterion with a solid-solid transition at 165°C was described. However, there is no evidence that this zwitterion exhibits plastic behavior, as, in addition to a low melting entropy, a plastic zwitterion must show evidence of disorder, preferably as determined by NMR studies. Furthermore, this compound is not used as a solid-state electrolyte.

[0009] The reference herein to a patent document or any other matter believed to be prior art is not to be taken as an admission that the document or other matter was known or that the information it contained was part of the common general knowledge as at the priority date of any claim.

[0010] When any and all terms "comprises," "comprising," "including," or "containing" are used in this specification (including the claims), they should be interpreted as specifying the presence of stated features, integers, steps or components, but not excluding the presence of one or more other features, integers, steps or components. SUMMARY OF THE INVENTION

[0012] Prior to the present disclosure, it was not known that certain organic zwitterionic compounds exhibit plasticity in the solid state as evidenced by molecular disorder.

[0013] In a first aspect, the present invention provides a zwitterionic plastic crystal (ZIPC) compound in the form of a non-polymeric molecule comprising:

[0014] at least one positively charged functional group carrying at least one positive charge, and

[0015] at least one negatively charged functional group carrying at least one negative charge, wherein

[0016] The positively charged functional group and the negatively charged functional group are covalently linked together in the molecule, and the zwitterionic compound has a net charge of zero, and wherein the compound exhibits molecular disorder in the solid state, wherein the compound exhibits two or more of the following:

[0017] - thermal behavior including one or more solid-solid phase transitions prior to melting;

[0018] - one or more NMR linewidths of 20 kHz or less in the solid state; and

[0019] - A microstructure or morphology including slip and glide planes observable on SEM analysis. Desirably, the NMR line width is 10 KHz or less, preferably 5 KHz or less, and in some embodiments 1 KHz or less.

[0020] In a second aspect, the present invention provides a zwitterionic plastic crystal (ZIPC) compound exhibiting molecular disorder in the solid state, having one of the general structures of claim 12 .

[0021] In a third aspect, the present invention provides a zwitterionic plastic crystal (ZIPC) compound exhibiting molecular disorder in the solid state, having one of the structures of claim 13 .

[0022] In a fourth aspect, the present invention provides a compound exhibiting molecular disorder in the solid state, having one of the following structures:

[0023]

[0024] In a fifth aspect, the present invention provides use of the compound of the first to fourth aspects as a solid solvent.

[0025] In a sixth aspect, the present invention provides use of the compound of the first to fourth aspects as an electrolyte matrix, preferably a solid electrolyte matrix.

[0026] In a seventh aspect, the present invention provides the use of a compound according to the first to fourth aspects as a conductivity enhancing additive in an electrolyte, preferably wherein the electrolyte is a polymer-based electrolyte or an ionic liquid-based electrolyte.

[0027] In an eighth aspect, the present invention provides a method for identifying a zwitterionic plastic crystal (ZIPC) compound comprising the steps of:

[0028] (i) providing a non-polymeric zwitterionic compound comprising: at least one positively charged functional group carrying at least one positive charge, and at least one negatively charged functional group carrying at least one negative charge, wherein the positively charged functional group and the negatively charged functional group are covalently linked together in a molecule, and the net charge of the zwitterionic compound is zero,

[0029] (ii) establishing the zwitterionic compound as a zwitterionic plastic crystalline (ZIPC) compound by screening the zwitterionic compound for evidence of molecular disorder in the solid state that identifies the zwitterionic compound as a zwitterionic plastic crystalline (ZIPC) compound, wherein the molecular disorder is evidenced by the compound exhibiting two or more of the following:

[0030] - thermal behavior including one or more solid-solid phase transitions prior to melting;

[0031] - one or more NMR line widths of 20 kHz or less in a static solid-state NMR spectrum; and

[0032] - Microstructure or morphology including slip and sliding planes on SEM analysis. Desirably, the NMR line width is 10 KHz or less, preferably 5 KHz or less, and in some embodiments 1 KHz or less.

[0033] In a ninth aspect, the present invention provides a zwitterionic plastic crystal (ZIPC) compound obtainable by the method of the eighth aspect.

[0034] In a tenth aspect, the present invention provides a zwitterionic plastic crystal composition in liquid form, comprising the zwitterionic plastic crystal (ZIPC) compound according to the first to fourth aspects or the ninth aspect, and an ionic salt, an acid, a base, a Li or Na functionalized polymer, or a combination thereof.

[0035] In an eleventh aspect, the present invention provides a zwitterionic plastic crystal composition in solid form, comprising a zwitterionic plastic crystal (ZIPC) compound according to the first to fourth aspects or the ninth aspect, and an ionic salt, an acid, a base or a Li or Na functionalized polymer or a combination thereof.

[0036] In a twelfth aspect, the present invention provides use of the zwitterionic plastic crystal (ZIPC) compound according to the first to fourth aspects or the ninth aspect, or the zwitterionic plastic crystal (ZIPC) composition according to the ninth or tenth aspect, in applications requiring ion conduction, such as the following: electrochemical cells, including electrochemical devices, preferably fuel cells, supercapacitors, dye-sensitized solar cells, or energy storage devices such as Na batteries or Li batteries.

[0037] In a thirteenth aspect, the present invention provides use of the zwitterionic plastic crystal (ZIPC) compound according to the first to fourth aspects or the ninth aspect in proton form in applications requiring proton conduction, such as fuel cells.

[0038] In a fourteenth aspect, the present invention provides use of a zwitterionic plastic crystal (ZIPC) compound according to the first to fourth aspects or the ninth aspect doped with a base as an anhydrous proton conductor, preferably wherein the base is imidazole.

[0039] In a fifteenth aspect, the present invention provides a solid electrolyte comprising the zwitterionic plastic crystal (ZIPC) compound according to the first to fourth aspects or the ninth aspect.

[0040] In a sixteenth aspect, the present invention provides a solid electrolyte comprising the solid composition of the tenth or eleventh aspect.

[0041] In a seventeenth aspect, the present invention provides the use of an energy storage device comprising an electrolyte comprising a zwitterionic plastic crystal (ZIPC) matrix, optionally doped with an ionic salt, an acid, a base, a Li or Na functionalized polymer, or a combination thereof.

[0042] In an eighteenth aspect, the present invention provides use of the energy storage device according to the seventeenth aspect, wherein the energy storage device is a Na battery or a Li battery.

[0043] In a nineteenth aspect, the present invention provides a fuel cell device comprising an electrolyte comprising a zwitterionic plastic crystal (ZIPC) matrix, optionally doped with an ionic salt, an acid, a base, a Li or Na functionalized polymer, or a combination thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Embodiments of the present invention will be described herein by way of example only with reference to the accompanying drawings, in which:

[0045] Figure 1-1A illustrates the structures of a number of new zwitterionic plastic crystals (ZIPCs) and compares them to a number of similar established OIPCs. Compounds 1, 2, 5, and 6 are novel compounds prepared on demand through custom synthesis at Boron Molecular. Novel compounds 3 and 4 were prepared at Deakin University. Compounds 7, 8, and 9 are commercially available but have not been previously described as plastic crystals; and Figure 1B illustrates thermal analysis information for pure ZIPC1, ZIPC2, ZIPC5, and ZIPC6. Figure 1C Shown are the cations and anions used to combine to form the ZIPC.

[0046] Figure 2-2A illustrates differential scanning calorimetry (DSC) heating traces of (a) ZIPC1 and 10 mol% LiFSI-doped ZIPC1, and (b) pure [C2mpyr][BF4]OIPC and 10 mol% LiFSI-doped [C2mpyr][BF4]OIPC. The heating / cooling rate is ±10 K / min; Figure 2-2B illustrates the DSC heating trace of (a) ZIPC1 and an electrolyte mixture of 90 mol% LiFSI in ZIPC1;

[0047] Figure 3-3A shows SEM images and microstructures of (a) pure ZIPC1 (as pellets) and (b) 10 mol% LiFSI in ZIPC1; 3B shows an SEM image of an electrolyte mixture of 90 mol% LiFSI in ZIPC1; 3C shows an SEM image of ZIPC6 (pellets prepared and images collected at room temperature); 3D shows an SEM image of a NaF surface; 3E shows an SEM image of pure ZIPC5 pressed into pellets at room temperature;

[0048] Figure 4-4A shows the ionic conductivity of pure ZIPC1 and [C2mpyr][BF4]OIPC and their mixtures with LiFSI as a function of temperature; Figure 4Aa is the ionic conductivity of 10 mol% LiFSI in ZIPC1 and OIPC. Figure 4Ab is the relationship between their spectral line width and temperature. Figure 4Ac Ionic conductivity of pure ZIPC, OIPC, and their mixtures with 10 mol% LiFSI; 4B shows the ionic conductivity of pure ZIPC1 and the electrolyte mixture of 90 mol% LiFSI in ZIPC1 as a function of temperature;

[0049] Figure 5-5A illustrates the variable temperature-static behavior of (a) 10 mol% LiFSI-doped OIPC and (b) 10 mol% LiFSI-doped ZIPC1. 7 Li spectra, and (c) as a function of temperature 7 Comparison of Li line width; 5B illustrates (a) variable temperature-static of 90 mol% LiFSI and ZIPC1 electrolyte mixture 7 Li spectrum, (b) variable temperature-static of pure LiFSI 7 Li spectrum, (c) variable temperature-static of 90 mol% LiFSI and ZIPC1 electrolyte mixture 19 F spectrum and (d) the mixture of 90 mol% LiFSI and ZIPC1 electrolyte as a function of temperature 7 Li and 19 F line width; 5C (a) shows the pure ZIPC5 1H single pulse spectrum; 5C(b) shows that pure ZIPC5 changes with temperature 19 F single pulse spectrum; 5D (a) ionic conductivity of 10 mol% LiFSI in ZIPC5; 5D (b) DSC trace of 10 mol% LiFSI in ZIPC5; 5D (c) SEM image of 10 LiFSI in ZIPC5;

[0050] FIG6 illustrates a) variable temperature-static behavior of 10 mol % LiFSI-doped ZIPC1 and 10 mol % LiFSI-doped OIPC at 20°C and 60°C. 19 F spectrum; and b) BF4 in OIPC and BF3 in ZIPC1 19 F line width; c) FSI as a function of temperature 19 F spectral line width; d) shows a single pulse of ZIPC1 as a function of temperature 19 F spectrum. Note that for crystalline solids, the line widths will be very broad and >100 ppm; e) Describe (i) the 19F NMR line widths of ZIPC1 as a function of temperature; (ii) the area fraction of the narrow 19F peak in ZIPC1 as a function of temperature, which is obtained from 19 Deconvolution of the F static NMR spectrum was obtained. The blue dashed lines separate the different thermal phases as determined by DSC.

[0051] FIG7A illustrates the 10 mol% LiFSI-doped ZIPC1 and 10 mol% LiFSI-doped OIPC measured by PFG-NMR at different temperatures. 7 Li, 19 F and 1 Comparison of H diffusion coefficients. The red curve is OIPC and the black curve is ZIPC1; 7B shows the H diffusion coefficients of a mixture of 90 mol% LiFSI and ZIPC1 electrolyte measured by PFG-NMR at different temperatures. 7 Li (black) and 19 F (red) diffusion coefficient;

[0052] Figure 8 The results show that 10 mol% LiFSI doped ZIPC1 at 50 °C has a high conductivity at 0.05 mV S -1 Cyclic voltammogram under the conditions of ;

[0053] Figure 9-9A illustrates the chronoamperometry of Li|10 mol% LiFSI-doped ZIPC1 electrolyte|Li battery at 50°C with a potential step of 10 mV; Figure 9-9B illustrates the chronoamperometry of Li|90 mol% LiFSI electrolyte mixture in ZIPC1|Li battery at 50°C with a potential step of 10 mV;

[0054] Figure 10-10A illustrates a) Li|Li symmetric cell cycling of 10 mol% LiFSI in ZIPC1 at different current densities using 1 hour polarization time (10 cycles at each current density) at 50°C; Figure 10-10B illustrates a) Li|Li symmetric cell cycling of 10 mol% LiFSI and ZIPC1 electrolyte mixture at 0.1 mA / cm3 at 50°C; 2 Symmetrical battery cycling performance under conditions of;

[0055] Figure 11 The cycling performance of (lithium iron phosphate) LFP|10 mol% LiFSI in ZIPC1|Li at 50°C in the range of 2.8 to 3.8 V is illustrated.

[0056] Figure 12 It is illustrated that the DSC trace of ZIPC7 shows three peaks in the heating cycle (T1 = 92 °C; ΔH = 26 J / g; T2 = 106 °C; ΔH = 10 J / g; T3 = 119 °C; ΔHf = 25 J / g) (melting point of imidazole = 89 °C) and the effect of imidazole doping at different concentrations;

[0057] Figure 13 Illustration a) Conductivity of pure proton ZIPC7 and when doped with different amounts of imidazole base. The conductivity of each sample was measured in triplicate.

[0058] Figure 14 Results illustrating the electrical conductivity of triflic acid-doped proton ZIPC7.

[0059] Figure 15 Illustrated are the conductivity and symmetric lithium battery performance of the liquid 50 mol% LiFSI electrolyte in ZIPC1; (a) ionic conductivity and viscosity (inset - DSC trace of liquid electrolyte); b) DSC at 0.2 mA cm at 50 °C. -2 , Li│Li symmetric battery voltage curve under the condition of polarization time 1h / stage c) Li│Li symmetric battery cycle under the condition of different current density at 50℃ and polarization time 1h / stage; and

[0060] Figure 16 DSC traces of pure ZIPC1 and its mixtures with 10 mol% and 90 mol% LiBF4, b) and c) SEM images of 10 mol% and 90 mol% LiBF4 in ZIPC1, d) and e) temperature dependence of 10 mol% and 90 mol% LiBF4 in ZIPC1. 7 Li single pulse static NMR spectra, f and g) are the temperature changes of 10mol% and 90mol% LiBF4 in ZIPC1, respectively. 19 F single pulse static NMR spectrum;

[0061] Figure 17 Ionic conductivity of a) pure ZIPC1 and its mixture with 10mol% and 90mol% LiBF4, b) 10mol% and 90mol% LiBF4 in ZIPC1 at different temperatures 7 Li and 19 F diffusion coefficient; and

[0062] Figure 18 Illustrated are the cyclic voltammograms of a) 10 mol % and b) 90 mol % LiBF4 in ZIPC1 at 50 °C, which is plotted at 0.05 mV s -1 The scan rate was collected using a stainless steel working electrode relative to a Li metal reference electrode.

[0063] Detailed description of the invention

[0064] The present inventors have unexpectedly discovered that covalently linking certain cations and anions, preferably from OIPC, together can form zwitterionic plastic crystal (ZIPC) compounds. Such ionic linkage reduces / eliminates the net matrix ion migration observed for OIPC in an electric field. Ionic linkage increases target ion transport through the ZIPC, for example by doping the ZIPC electrolyte matrix with a target ion source. Plastic zwitterions address the low target ion migration number problem observed in existing solid electrolyte matrices (e.g., OIPC electrolyte matrices, which result from translational migration of OIPC matrix ions). The solution involves eliminating the migration of undesirable matrix OIPC ions by using a ZIPC matrix in which positive and negative charges are linked together in a net neutral molecule that does not move in an electric field, while the unexpected ZIPC plasticity (resulting from the unexpected retention of all disorder in the ZIPC) achieves high target ion conductivity when the ZIPC electrolyte matrix is ​​doped with a salt of the target ion. Unexpectedly, the charge connected in the single molecule will provide these benefits, because the connection will be expected to reduce the chance of rotation and translation disorder. Unexpectedly, the compound that some ions are connected shows plasticity and the ZIPC of the present invention will show enough disorder to realize better target ion transmission in solid matrix. No research has been done before to propose that the connection ions of organic ion plastic crystals will form plastic zwitterions, because ions are connected and the quantity that the expected disorder motion (rotation and translation) is reduced, so such ions are connected and the expected production of usually ordered crystalline compounds, thus contrary to the teaching of zwitterionic plastic crystal compounds of the present invention. In addition, such matrix is ​​expected to lack practicality in terms of assisting target ion dissociation from the salt provided to the electrolyte matrix. The zwitterions described in this area are not mentioned and can show a better target ion migration number than corresponding OIPC.

[0065] The ZIPCs of the present invention provide improved solid-state conductivity and transport of target ions (e.g., Li+, Na+, H+) while suppressing counterion transport, which is a significant challenge for OIPCs. This is demonstrated by high transference numbers, such as (t Li+ ) is 0.7. The typical transference number of the Li salt in OIPC is <0.2. ZIPC is particularly suitable for use in batteries with metal anodes such as lithium or sodium metal anodes.

[0066] Furthermore, protic and aprotic ZIPCs provide improvements in proton conductivity relative to protic and aprotic OIPCs.

[0067] ZIPCs are a new class of materials proposed as (i) host materials for salt-doped solid electrolytes, particularly for Li-containing batteries. + Or Na + materials, (ii) as additives to other electrolytes to promote the absorption of target ions, especially Li + Or Na + ion dissociation and transport, (iii) as a proton conducting material for proton exchange membrane (PEM) fuel cells when doped with acid or base and / or (iv) as a replacement for OIPC in existing ion conductor applications. In aspect (i), the new ZIPC electrolyte material has a conductivity of >10 -9 S cm -1 The high ionic conductivity and t Li+ >0.2.

[0068] In Li and Na batteries, the ZIPCs of the present invention can be used as additives in other electrolytes, such as polymer-based electrolytes or ionic liquid-based electrolytes, to promote the dissociation of target ions and enhance the mobility and transport of target ions through the electrolyte. This can be achieved by the ZIPC, which provides another (charge diffusion) negatively charged site to interact with the positively charged target ions (such as Li + Or Na + ) interacts with Li + It competes with the interaction with its counterion from the salt, thereby promoting ion dissociation.

[0069] In the field of polymer-based solid electrolytes, ZIPCs are used as additives to improve the dissociation of carrier ions from the polymer backbone (or other ionic species present).

[0070] Using ZIPC in similar OIPC applications can advantageously result in higher conductivity for specific target ions.

[0071] In addition, the ZIPC of the present invention, especially the one having the zwitterion -BF3- Those with comparable BF4 structures - The material is less prone to hydrolysis. Thus, even in battery applications, where electrolytes are typically used under an inert atmosphere, the use of ZIPC compounds in devices containing electrochemical cells can advantageously provide longer-term device / cell stability due to a reduced tendency toward hydrolysis. This is particularly important for fuel cells.

[0072] The present inventors extended the concept of protonated zwitterions (with mobile protons) and demonstrated that protonated ZIPCs achieve good proton conduction.

[0073] Suitably, the preferred ZIPC is non-volatile.Desirably, the preferred compound is not flammable or explosive, at least under typical operating conditions of a fuel cell or energy storage device.

[0074] Suitably, ZIPC compounds exhibit a long-range, ordered crystal structure and short-range disorder originating from the rotation or disorientation of molecules within the ordered lattice. For ZIPCs, it is understood that solid-solid phase transitions are associated with the onset of rotational motion of all or part of the ZIPC molecules. The combination of spectroscopic and simulation methods can be a powerful tool for further elucidating the interplay between chemistry, structure, and phase behavior in ZIPCs and can serve as a predictor of plastic behavior in zwitterions as described herein.

[0075] Molecular disorder (and hence plasticity) associated with ZIPC can be observed, for example, from characteristic features in at least two or more of thermal studies, solid-state NMR studies, and SEM studies. Notably, one or more of the characteristic features may increase with increasing temperature.

[0076] One characteristic feature may include thermal phase behavior, which includes one or more solid-solid phase transitions prior to melting (pre-melting or sub-melting solid-solid phase transitions). Techniques for measuring and characterizing the solid-solid phase transitions of ZIPCs include differential scanning calorimetry, whereby the solid-solid phase transitions are characterized by DSC curves in which a discontinuity (e.g., a surge) in heat flow is observed in the sub-melting temperature range, which is in addition to and distinct from the discontinuity caused by the solid-liquid (melting) transition of the ZIPC.

[0077] Another characteristic feature of molecular disorder in the solid state is determined by static solid-state NMR, whereby plastic ZIPCs exhibit one or more NMR line widths of 20 kHz or less. Desirably, the line widths further narrow with increasing temperature. Desirably, the NMR line widths are 10 kHz or less, preferably 5 kHz or less, and in some embodiments, 1 kHz or less.

[0078] Another characteristic feature of molecular disorder in the solid state was determined by observing the microstructure / morphology using SEM analysis. Characteristic features included the observation of multiple grains with different orientations, the observation of sliding and slip planes on SEM analysis, multiple sets of slip planes within different grains, and the observation of grain boundaries from fracture surfaces of the material. Further evidence of plasticity was found to increase with increasing temperature.

[0079] Another characteristic feature may include exhibiting the melting entropy ΔS f , which is less than about 60JK -1 mol -1 , more preferably less than about 50JK -1 mol -1 , more preferably less than about 40JK -1 mol -1 , more preferably less than about 30JK -1 mol -1 , more preferably less than about 20JK -1 mol -1 .

[0080] Other studies that may be used include X-ray diffraction, Raman spectroscopy, synchrotron X-ray diffraction and molecular simulations such as molecular dynamics (MD) or a combination thereof.

[0081] Preferred ZIPC compounds are plastic solids at application operating temperatures, for example, between about -100°C and about 200°C, between about -50°C and about 100°C, and most preferably between about -10°C and about 80°C. Particularly preferred compounds are plastic solids at least at room temperature. "Room temperature" means a temperature between about 20°C and about 25°C, preferably 25°C. Preferred ZIPC compounds have a melting point of ≥60°C, ≥70°C, ≥80°C, ≥80°C, ≥100°C, ≥150°C, ≥200°C, or ≥250°C. Preferred compounds exhibit plastic behavior at temperatures from about -100°C to about 100°C. The melting point determines the upper normal operating temperature of the equipment using the ZIPC. "Melting point" means the extrapolated onset temperature associated with the phase transition from solid to liquid, as determined by differential scanning calorimetry (DCS). When a compound exhibits plasticity at very low temperatures, such as <0°C, it generally indicates that the compound will be advantageously very disordered at room temperature.

[0082] It is believed that when used as an electrolyte, the plastic crystals provide an environment through which the target ions added can move, for example, through vacancies, grain boundaries and / or form additional liquids, liquid-like amorphous phases. In fact, SEM analysis of many electrolyte materials containing lithium salts shows that the crystalline regions and intergranular regions contain mobile, Li-rich electrolytes, providing pathways for lithium ions to support lithium electrochemistry and device cycling. Therefore, it is believed that the solid materials of the present invention comprising ZIPC and doped salts contain one or more of a liquid phase or a liquid-like phase or an amorphous phase, for example, that is rich in salt. Therefore, the material contains more than one phase. It is believed that the liquid phase rich in target ions or the liquid-like phase rich in target ions or the amorphous phase rich in target ions provide pathways for target ion diffusion and promote target ion transport through the electrolyte.

[0083] In some cases where the functional group carrying a positive charge comprises an alkyl chain, one or more of the melting temperature and the phase II-I transition temperature may decrease with increasing alkyl chain length.

[0084] ZIPCs can be classified into proton and aprotic categories, which depend on the availability of dissociable protons on the cation and / or anion components of the zwitterionic molecule. Thus, some suitable cations can be protons or aprotic cations, depending on the availability of (one or more) labile protons. Similarly, some suitable anions can be protons or aprotic anions, depending on the availability of (one or more) labile protons.

[0085] ZIPC Formation - One can start with at least one cation and at least one anion and covalently link them together to provide a ZIPC. There is no particular limitation on the type of cation and associated counteranion that can be used, as long as the combination of cation and anion that is linked together provides: (i) a zwitterionic compound with a net neutral charge, and (ii) is a plastic crystal that exhibits molecular disorder (and thus plasticity), as observed, for example, from characteristic features in two or more of thermal studies, solid-state NMR studies, and SEM studies.

[0086] In preferred ZIPC compounds, at least one positive functional group of the ZIPC is derived from a small cationic component, such as an optionally substituted saturated or unsaturated heterocycle, for example, pyrrolidine, morpholinium, piperidinium, tetrahydrothiophene, benzotriazole or tetrahydrofuran. Desirably, at least one negative functional group of the preferred ZIPC is derived from a charge delocalized anionic group, such as fluoroborate, oxalatoborate, sulfonimide, fluorosulfonimide (FSI), bis(trifluoromethanesulfonyl)imide (TFSA). "Derived from" means that the respective cations or anions form the basis of the corresponding functional groups that are covalently bonded together, either directly or through at least one atom or intermediate functional group, which may be, for example, a carbon bond or hydrocarbon chain or indeed another functional group, ring or chain. It will be understood that due to the linkage of the functional groups in the ZIPC molecule, the corresponding functional groups derived from the cations and anions do not readily dissociate from one another, especially under the influence of an electric field.

[0087] Cationic components for attachment - Some suitable cations can be divalent or trivalent cations. Preferred cations are symmetrical. In some embodiments, the cation is a chiral cation.

[0088] Examples of suitable cations include pyrrolidinium, imidazolium, phosphonium, metallocenium cations, which may be unsubstituted or substituted with one or more functional groups selected from: C 1-6 Alkyl, preferably methyl, ethyl or propyl, CN, OMe, OEt and CN.

[0089] Suitably, one or more of the positively charged functional groups may be selected from the following cations and in particular aprotic cations: C n (N 2,2,m )2where n=2, 3, 4, 6 and m=1, 2, 3, 4, 6; N 2,1,1,1 ; N 2,2,1,1 ; N 2,2,2,1 ; N 2,3,3,3 ; N 2,2,3,3 ; N 2,2,2,3 ; N 4,4,4,4 ;P 1,2,2,2 ; N 1,2,3,i3 ; N 2,2,2,2 ; N 3,3,3,3 Cations capable of rotational motion (e.g., tetramethylammonium) are particularly desirable.

[0090] Desirably, the at least one positively charged functional group carrying at least one positive charge is derived from an ammonium cation, a phosphonium cation, or a sulfonium cation, which contain positively charged nitrogen, positively charged phosphorus, and positively charged sulfur, respectively.

[0091] Desirably, at least one positively charged functional group carrying at least one positive charge is derived from an ammonium cation containing nitrogen and having a positive charge. Preferred ammonium cations may have the general formula [NR 4 R 3 R 2 R 1 ] + Desirably, at least one positively charged functional group carrying at least one positive charge is derived from a sulfonium cation containing sulfur and having a positive charge. Preferred sulfonium cations may have the general formula [SR 3 R 2 R 1 ] + Desirably, at least one positively charged functional group carrying at least one positive charge is derived from a phosphonium cation containing phosphorus and having a positive charge. Preferred phosphonium cations may have the general formula [PR 4 R 3 R 2 R 1 ] + .

[0092] In each of the above cases, R 1 to R 4 Each of the R groups may be the same or different and may be independently selected from optionally substituted alkyl and optionally substituted aryl, or one of the R groups may be selected from optionally substituted alkyl and optionally substituted aryl and the remaining two R groups together with P form an optionally substituted heterocyclic ring, and R 1 is selected from H, optionally substituted alkyl and optionally substituted aryl. Examples of suitable phosphonium cations include tetra(C 1-20 alkyl)phosphonium, tri(C 1-9 Alkyl)mono(C 10-20 alkyl)phosphonium, tetra(C 6-24 aryl)phosphonium, phospholanium, phosphinanium and phosphorinanium.

[0093] Desirably, at least one of the positively charged functional groups carrying at least one positive charge is derived from a morpholinium cation, a pyrrolidinium cation, or an imidazolium cation, each of which contains a nitrogen having a positive charge. The ring of the pyrrolidinium cation or the imidazolium cation may be unsubstituted or substituted with R 1 and R 2 In each case, R 1 and R 2 Each of the R groups may be the same or different and may be independently selected from optionally substituted alkyl and optionally substituted aryl, or one of the R groups may be selected from optionally substituted alkyl and optionally substituted aryl and the remaining two R groups together with P form an optionally substituted heterocyclic ring, and R 1is selected from H, optionally substituted alkyl and optionally substituted aryl.

[0094] Other preferred cations for use in conjunction with suitable anions include dialkylpyrrolidinium, pyrrolidinium, monoalkylpyrrolidinium, dialkylimidazolium, monoalkylammonium, imidazolium, tetraalkylammonium, quaternary ammonium, trialkylammonium, dialkylammonium, dialkylammonium, dialkanolalkylammonium, alkanodialkylammonium, bis(alkylimidazolium), bis(dialkyl)ammonium, bis(trialkyl)ammonium, diallylammonium, dialkanolammonium, alkylalkanolammonium, alkylallylammonium, guanidinium, diazonium, Heterobicyclooctanes, tetraalkylphosphoniums, trialkylphosphoniums, trialkylsulfoniums, tertiarysulfoliniums, imidazoliniums, choliniums, formamidiniums, formadiniums, bicyclic (spiro)ammoniums, pyrazoliums, benzimidazoliums, dibenzylammoniums, caffineiums, piperaziniums, dialkyl (amino)ammoniums, alkyl (diamino)ammoniums, triaminoammoniums, aminopyrrolidiniums, and aminoimidazoliums.

[0095] Other cations for attachment may be selected from Figure 1C The cations described in .

[0096] In one embodiment, desirably, at least one of the positively charged functional groups carrying at least one positive charge is derived from a cation from an ionic liquid or, more preferably, an OIPC. Desirably, at least one of the negatively charged functional groups carrying at least one negative charge is derived from an anion from an ionic liquid or an OIPC. Suitably, the ZIPC of the present invention can be formed by linking together at least one cation from an ionic liquid or an OIPC and at least one anion from an ionic liquid or an OIPC in the same molecule. A skilled synthesizer will be able to design a suitable synthetic method to form a compound in which the desired groups are linked together.

[0097] Examples of cations and anions of OIPCs that can be used as starting points for designing ZIPC compounds of the present invention are found in Trends in Chemistry, April 2019, Vol. 1, No. 1; J. Mater. Chem., 2010, 20, 2056–2062 and Phys. Chem. Chem. Phys., 2013, 15, 1339 (particularly FIG. 1 , FIG. 2 , FIG. 3 and Table 1 ), the entire contents of which are incorporated herein by reference for describing cations and anions and OIPCs. Preferred examples of known OIPCs include [N 1,1,1,1 ][DCA],[C2mpyr][FSI],[C2mpyr][BF4],[P 1,2,2,2 ][FSI]、[P 1,2,2,i4 ][PF6]、[P 1,4,4,4][FSI],[H2im][Tf],[Hmim][Tf],[N 2,2,3,3 ][BBu4]、[N 3,3,3,3 ][BF4],[C2epyr][TFSI],[C2epyr][FSI],[C2epyr][PF6],[C2epyr][BF4],[C1mpyr][(FH )2F] and [C2mpyr][(FH)2F], [C4mpyr][TFSI], [(NH2)3][Tf], [2-Me-im][Tf] and [TAZm][PFBS].

[0098] Anionic component for attachment - Suitably, at least one of the negatively charged functional groups carrying at least one negative charge may be derived from an anion from a known OIPC. Some preferred anions may be protic or aprotic anions, depending on the availability of the labile proton(s). Some preferred anions may be divalent or trivalent anions. Some preferred anions may be symmetric. Some preferred anions may be chiral.

[0099] Preferred anions useful for attachment may possess a "globular" structure, whereby the anion has a configurational shape that exhibits spherical symmetry about its center by rotation about an axis. Additional anions suitable for attachment in the ZIPC electrolyte compositions of the present invention may be anions with diffuse or mobile negative charges that, when attached in a ZIPC compound, can reside or be evenly distributed throughout the anionic structure.

[0100] Suitably, one or more of the negatively charged functional groups may be selected from the following anions and in particular aprotic anions: Tf, (FH) n F (where 1≤n≤3) and TFSI. Other suitable anions for forming one or more negatively charged functional groups can be selected from the following anions: I, Br, PF6, TFSI, BBu4, CrO3Cl, CrO3Br, BF4, FTFSI, DCA, FSI and Tf. Centrosymmetric anions (such as hexafluorophosphate and tetrafluoroborate) are particularly preferred.

[0101] Desirably, at least one negatively charged functional group (F - ) is derived from anions such as BF4 - PF6 - 、N(CN)2、(CF3SO2)2N - 、(FSO2)2N - , OCN, SCN -, dicyanomethyl anion, carbamoylcyano(nitroso)methyl anion, (C2F5SO2)2N - 、(CF3SO2)3C、C(CN)3 - 、B(CN)4 - 、(C2F5)3PF3 - , alkyl-SO3 - , perfluoroalkyl-SO3 - , aryl-SO3 - , I - 、H2PO4 - 、HPO4 2- , sulfate, sulfite, nitrate, trifluoromethanesulfonate, p-toluenesulfonate, bis(oxalato)borate, acetate, formate, gallate, glycolate, BF3(CN) - 、BF2(CN)2 - 、BF(CN)3 - 、BF3(R) - 、BF2(R)2 - 、BF(R)3 - (wherein R is an alkyl group (e.g., methyl, ethyl, propyl)), a cyclic sulfonamide anion, bis(salicylate)borate, perfluoroalkyltrifluoroborate, chloride, bromide, and a transition metal complex anion (e.g., [Tb(hexafluoroacetylacetonate)4]). Preferably, the anion is a fluorinated anion, for example, selected from the group consisting of: BF4 - PF6 - 、(CF3SO2)2N - 、(FSO2)2N - 、BF3(CN) - 、BF2(CN)2 - 、BF(CN)3 - 、BF3(R) - 、BF2(R)2 - 、BF(R)3 - (wherein R is an alkyl group (e.g., methyl, ethyl, propyl, butyl)), (C2F5SO2)2N - 、(C2F5)PF3 - , (C2F5PO2)2N, (CF3SO2)NCN, (CF3SO2)N(SO2F), (CF3CO)N(SO2F) and perfluoroalkyl-SO3 - .

[0102] Other anions for attachment may be selected from Figure 1C The anions described in .

[0103] Examples of OIPC analogs - known OIPCs that can provide cations and anions for linking together in the same molecule to form ZIPCs according to the present invention, including protic and aprotic forms, include: N,N-methylethylpyrrolidinium tetrafluoroborate, N,N-methylpropylpyrrolidinium tetrafluoroborate, dimethylpyrrolidinium tetrafluoroborate, dimethylpyrrolidinium thiocyanate, N,N-ethylmethylpyrrolidinium thiocyanate, Cyanate, tetramethylammonium dicyanamide, tetraethylammonium dicyanamide, N,N-methylethylpyrrolidinium bis(trifluoromethanesulfonyl)amine salt, diethyl(methyl)isobutyl)phosphonium bis(fluorosulfonyl)amine salt, diethyl(methyl)(isobutyl)phosphonium tetrafluoroborate, diethyl(methyl)(isobutyl)phosphonium hexafluorophosphate, methyl(triethyl)phosphonium bis(fluorosulfonyl)amine salt, methyl(triethyl)phosphonium bis(trifluoromethylsulfonyl)amine salt, triisobutyl( methyl)phosphonium hexafluorophosphate, triisobutyl (methyl)phosphonium bis (fluorosulfonyl) amine salt, triisobutyl (methyl)phosphonium tetrafluoroborate, triisobutyl (methyl)phosphonium thiocyanate, triethyl (methyl)phosphonium bis (fluorosulfonyl) imide salt, methylethyl pyrrolidinium bis (fluorosulfonyl) amine salt, dimethyl pyrrolidinium bis (fluorosulfonyl) amine salt, choline dihydrogen phosphate, choline trifluoromethanesulfonate, NN-dimethylpropylenediammonium trifluoromethanesulfonate, tri (isobutyl) ... phosphonium bis(trifluoromethanesulfonyl)amine salt, tri(isobutyl)phosphonium methanesulfonate, tri(isobutyl)phosphonium trifluoromethanesulfonate, tri(isobutyl)ammonium bis(trifluoromethanesulfonyl)amine salt, tri(isobutyl)phosphonium nitrate, tri(isobutyl)ammonium methanesulfonate, tri(isobutyl)ammonium trifluoromethanesulfonate, tri(isobutyl)ammonium nitrate, 1,2-bis[N-(N'-hexylimidazolium)ethane bis(hexafluorophosphate), and combinations thereof.

[0104] Preferred ZIPC - Particularly preferred zwitterionic plastic crystal (ZIPC) compounds have the structure shown herein. Preferably, one or more of R', R" and R'" are independently H, methyl, ethyl or propyl. Preferably, R 1 、R 2 and R 3 wherein each is independently selected from H, methyl, ethyl or propyl, or halogen. Preferably, Y is methyl, ethyl or propyl. Preferably, L is methyl, ethyl or propyl. Preferably, one or more of R', R" and R'" are independently methyl, ethyl or propyl; R 1 、R 2 、R 3 Where each is F; Y is methyl and L is methyl. Preferred compounds include:

[0105]

[0106]

[0107] Particularly preferred zwitterionic plastic crystal (ZIPC) compounds have one of the following general structures:

[0108]

[0109] wherein: one or more of R', R" and R'" are independently selected from H, or optionally substituted C 1-6 Alkyl, optionally substituted fluoroC 1-6 an alkyl or halogen group, or one of R' and R", R" and R'" or R' and R'"' forms an optionally substituted 5-membered or 6-membered saturated or unsaturated heterocyclic ring, R 1 、R 2 and R 3 Each is independently selected from H, optionally substituted C 1-6 Alkyl, optionally substituted fluoroC 1-6 Alkyl or halogen; Y is optionally substituted C 1-6 Alkyl; L is an optionally substituted C 1-6 and Z and Z' are each independently O, S, NH, N, C 1-4 alkyl; and each of X and X" is independently O, S, NH, N, C, CH; and when present, the ring is optionally substituted, wherein the optional substituents are selected from C 1-6 One or more of alkyl (preferably methyl, ethyl or propyl), CN, OMe, OEt and CN. Preferably, R 1 is H, methyl, ethyl or propyl; R 2 、R 3 、R 4 wherein each is independently selected from H, methyl, ethyl or propyl, halogen; Y is methyl, ethyl, or propyl; L is methyl, ethyl, or propyl; and Z is methyl or ethyl; and X is O, S, NH or CH. Preferably, R 1 is methyl, ethyl or propyl; R 2 、R 3 、R 4 where each is F; Y is methyl; L is methyl; and Z is methyl or ethyl; and X is O, S, NH, or CH.

[0110] Particularly preferred zwitterionic plastic crystal (ZIPC) compounds have one of the following general structures:

[0111]

[0112]

[0113] Wherein: R' is methyl, ethyl or propyl; R 1 、R 2 、R 3wherein each is F; Y is methyl; and X is O, S, NH, or CH.

[0114] Preferred ZIPC compounds have one of the following structures:

[0115]

[0116]

[0117]

[0118] The ZIPC of the present invention can be used as a solid solvent.

[0119] Electrolyte Compositions / Mixtures - Also described are compositions comprising a zwitterionic plastic crystal (ZIPC) compound according to the first aspect, doped with one or more of a salt, an acid, a base, or a polymer commonly used in electrolytes, such as a polymer Li- or Na-functionalized polymer. Suitably, such compositions can be solid or liquid at room temperature, depending on the amount of salt, the nature of the salt used, and the nature of the ZIPC used. Solid compositions are preferred, at least when the ZIPC is used as the matrix material of the composition / electrolyte.

[0120] To be used as a solid electrolyte (e.g. in batteries or fuel cells), the target ions (e.g. Li + 、Na + or H + ) are introduced into the ZIPC matrix to support the charge / discharge process. Doping even small amounts of ionic salts into the ZIPC matrix can significantly improve the ionic conductivity of the target ions in the ZIPC matrix. One explanation is that the introduction of ionic salts into the ZIPC creates additional vacancies / defects, leading to a higher concentration of diffusing ions and, therefore, higher conductivity. An alternative mechanism is that a liquid phase with a mixed (Li salt and ZIPC) composition exists at the grain boundaries of the otherwise mostly bulk ZIPC.

[0121] Preferably, the composition comprises ZIPC and at least one ionic salt, wherein the salt is present at a concentration of at least about 5 mol%. Suitably, the ionic salt is present at a concentration of at least about 5 mol%, at least about 10 mol%, at least about 15 mol%, at least about 20 mol%, at least about 25 mol%, at least about 30 mol%, at least about 35 mol%, at least about 40 mol%, at least about 45 mol%, at least about 50 mol%, at least about 55 mol%, at least about 60 mol%, at least about 65 mol%, at least about 70 mol%, at least about 75 mol%, at least about 80 mol%, at least about 85 mol%, at least about 90 mol%, at least about 95 mol%.

[0122] Suitably, the ionic salt is one or more of an alkali metal salt, an alkaline earth metal salt or a transition metal salt. Preferred ionic salts include Li salts, Na salts, K salts, Ca salts, Al salts, Mg salts, Zn salts. Suitably, the anions of these salts include bis(trifluoromethanesulfonyl)imide, TFSI; bis(fluorosulfonyl)imide, FSI; fluorosulfonyl(trifluoromethanesulfonyl)imide, FTFSI; trifluoromethane-sulfonate; tetrafluoro-borate, BF4; perfluorobutanesulfonate, PFBS; hexafluorophosphate, PF6; tetracyanoborate, B(CN)4; dicyanamide, DCA; thiocyanate, SCN; cyclic perfluoro-sulfonamide, CPFSA and carborane.

[0123] Desirably, the ionic salt is a lithium salt selected from, for example, LiBF4, LiFSI, lithium bis(trifluoromethanesulfonyl)imide (Li[TFSI]), lithium bis(fluorosulfonyl)imide (Li[FSI]), lithium trifluoromethanesulfonate (Li[OTf]), lithium perchlorate (LiClO4), lithium dicyanamide (LiDCA), lithium cyanate (LiOCN), lithium thiocyanate (LiSCN), lithium bis[(pentafluoro-ethyl)sulfonyl]imide, lithium 2,2,2-trifluoromethylsulfonyl-N-cyanamide (TFSAM), lithium 2,2,2-trifluoro-N-(trifluoromethylsulfonyl)acetamide (TSAC), lithium nonafluorobutanesulfonate (NF), lithium carborane, lithium difluoro(oxalato)borate, and combinations thereof.

[0124] Preferably, the doped salt is a Li salt such as LiNTf2, wherein the ZIPC composition has a transference number greater than 0.4 as determined electrochemically or by NMR. Such techniques are known in the art. An example of an electrochemical method for obtaining ion transference numbers is the Bruce Vincent method, which is well known in the art.

[0125] Desirably, the ionic salt is a sodium salt selected from, for example, NaBF4, NaFSI, sodium bis(trifluoromethanesulfonyl)imide (Na[TFSI]), sodium bis(fluorosulfonyl)imide (Na[FSI]), sodium trifluoromethanesulfonate (Na[OTf]), sodium perchlorate (NaClO4), sodium dicyanamide (NaDCA), sodium cyanate (NaOCN), sodium thiocyanate (NaSCN), lithium bis[(pentafluoro-ethyl)sulfonyl]imide, sodium 2,2,2-trifluoromethylsulfonyl-N-cyanamide (TFSAM), sodium 2,2,2-trifluoro-N-(trifluoromethylsulfonyl)acetamide (NaTSAC), sodium nonafluorobutanesulfonate (NaNF), sodium carborane, sodium difluoro(oxalato)borate, and combinations thereof. Particularly preferred Na salts include sodium bis(trifluoromethanesulfonyl)imide (Na[TFSI]), sodium bis(fluorosulfonyl)imide (Na[FSI]), sodium trifluoromethanesulfonate (NaOTf), sodium perchlorate (NaClO4), sodium dicyanamide (NaDCA), sodium cyanate (NaOCN), sodium tetrafluoroborate (NaBF4), sodium hexafluorophosphate (NaPF6), and combinations thereof.

[0126] Desirably, the ionic salt is an iodide salt selected from the group consisting of AgI, NaI, KI, guanidinium iodide, Nme4I, N(Pr)4I, N(Et)4I, and combinations thereof. The iodide salt is typically provided in combination with iodine such that the combination dissociates into I - / I3 - right.

[0127] Desirably, the ZIPC composition is doped with an acid or base. Introducing excess acid or base into the proton ZIPC is beneficial for high proton conductivity. It is believed that protons are primarily transported through the percolating grain boundary phase.

[0128] Preferably, the ZIPC composition comprises a ZIPC compound and an acid, wherein the acid is present at a concentration of at least about 5 mol%. Suitably, the acid is present at a concentration of at least about 5 mol%, at least about 10 mol%, at least about 15 mol%, at least about 20 mol%, at least about 25 mol%, at least about 30 mol%, at least about 35 mol%, at least about 40 mol%, at least about 45 mol%, at least about 50 mol%, at least about 55 mol%, at least about 60 mol%, at least about 65 mol%, at least about 70 mol%, at least about 75 mol%, at least about 80 mol%, at least about 85 mol%, at least about 90 mol%, at least about 95 mol%. Suitable acids include trifluoromethanesulfonic acid, bis(trifluoromethanesulfonyl)amide, methanesulfonic acid, sulfuric acid, phosphoric acid, nitric acid, formic acid, and tetrafluoroboric acid.

[0129] Preferably, the ZIPC composition comprises a ZIPC compound and a base, wherein the base is present at a concentration of at least about 5 mol%. Suitably, the base is present at a concentration of at least about 5 mol%, at least about 10 mol%, at least about 15 mol%, at least about 20 mol%, at least about 25 mol%, at least about 30 mol%, at least about 35 mol%, at least about 40 mol%, at least about 45 mol%, at least about 50 mol%, at least about 55 mol%, at least about 60 mol%, at least about 65 mol%, at least about 70 mol%, at least about 75 mol%, at least about 80 mol%, at least about 85 mol%, at least about 90 mol%, at least about 95 mol%. Suitable bases include imidazole, methylamine, ethylamine, propylamine, butylamine, tert-butylamine, 2-methoxyethylamine, 3-methoxypropylamine, dimethylamine, diethylamine, dibutylamine, N-methylbutylamine, N-ethylbutylamine, trimethylamine, triethylamine, tributylamine, N,N-dimethylethylamine, aniline, 2-fluoropyridine, 1-methylimidazole or 1,2-dimethylimidazole. Preferred bases include imidazole.

[0130] Preferably, the solid composition further comprises one or more additional components selected from the group consisting of polymers, particularly lithium or sodium functionalized polymers, binders such as PVDF, ionomers, dendrimers, and inorganic fillers to form a ternary composite material. In one embodiment, the solid composition may be provided in the form of a film.

[0131] Preferred compounds exhibit an ion mobility number greater than 0.4 when doped with an ionic salt such as an alkali metal ion, an alkaline earth metal ion, or a transition metal ion, as determined electrochemically or by NMR. More preferably, the ion mobility number is greater than 0.4, greater than 0.45, greater than 0.5, greater than 0.55, greater than 0.6, greater than 0.65, greater than 0.7, greater than 0.75, greater than 0.8, greater than 0.85, greater than 0.9, or greater than 0.95, as determined electrochemically or by NMR.

[0132] Preferred ZIPC compounds exhibit a lithium ion transference number greater than 0.4 when doped with lithium or sodium ions, as determined electrochemically or using NMR. More preferred ZIPC compounds exhibit an ion transference number greater than 0.5, 0.6, 0.7, 0.8, or 0.9 when doped with lithium or sodium ions. Most preferred ZIPC compounds exhibit an ion transference number of approximately 1 when doped with lithium or sodium ions.

[0133] Preferred ZIPC compounds exhibit a 10 -13 to 10 -10 m 2 s -1 , preferably 10 -13 to 10-8 m 2 s -1 , more preferably 10 -13 to 10 -6 m 2 s -1 The preferred mixture of the ZIPC compound and the lithium salt exhibits a lithium diffusion coefficient of at least 10 as measured by NMR at 25°C. -13 m 2 s -1 The most preferred mixture of the ZIPC compound and the lithium salt exhibits a lithium self-diffusion coefficient of at least 10 as measured by NMR at 25°C. -6 m 2 s -1 The lithium self-diffusion coefficient.

[0134] The ZIPC compound and / or the electrolyte composition comprising the ZIPC compound and at least an ionic salt is preferably solid, preferably up to at least 80° C. and preferably over a wide range of ionic salt concentrations, while maintaining high ionic conductivity.

[0135] The electrolyte compositions of the present invention advantageously provide high ionic conductivity at lower temperatures than most polymer electrolytes. As a result, electrochemical cells based on the electrolytes can operate at lower temperatures than conventional solid-state batteries.

[0136] The electrolyte composition of the present invention can advantageously exist as a solid over a wide range of ionic salt concentrations up to a desired temperature. Preferably, the ZIPC compound and / or the electrolyte of the matrix comprising the doped ZIPC compound exists as a solid up to a temperature of at least 30°C, at least 40°C, at least 50°C, at least 60°C, at least 70°C, at least 80°C, at least 90°C, at least 100°C, at least 110°C, at least 120°C, at least 130°C, at least 140°C, at least 150°C, at least 160°C, at least 170°C, at least 180°C, at least 190°C, at least 200°C, at least 210°C, at least 220°C, at least 230°C, at least 240°C, or at least 250°C.

[0137] In some embodiments, the ZIPC and / or electrolyte composition of the present invention is solid throughout the composition, meaning that the entire volume of the electrolyte composition is in the solid state. However, if the ZIPC and / or electrolyte is present as a solid, a portion of the matrix / composition may be in the liquid phase. As long as the material / composite exists as a solid up to the desired temperature, there is no limit to the extent to which the proportion of the matrix / composition is in the liquid phase. One skilled in the art will be able to determine a suitable value for the volume fraction of a given material that is in the liquid phase based on the material's phase diagram.

[0138] In some embodiments, the electrolyte composition of the present invention may exist at a volume fraction in the liquid phase at a temperature of up to at least 30°C, at least 40°C, at least 50°C, at least 60°C, at least 70°C, at least 80°C, at least 90°C, at least 100°C, at least 110°C, at least 120°C, at least 130°C, at least 140°C, at least 150°C, at least 160°C, at least 170°C, at least 180°C, at least 190°C, at least 200°C, at least 210°C, at least 220°C, at least 230°C, at least 240°C, at least 250°C, at least 300°C, or at least 350°C.

[0139] There are no particular limitations on the concentration of ionic salts in the solid ZIPC compositions of the present invention. However, preferably, the composition exists as a solid until at least 50°C. In some embodiments, the ions are present at a concentration of at least 5 mol%, at least 10 mol%, at least 15 mol%, at least 20 mol%, at least 25 mol%, at least 30 mol%, at least 35 mol%, at least 40 mol%, at least 45 mol%, at least 50 mol%, at least 55 mol%, at least 60 mol%, at least 65 mol%, at least 70 mol%, at least 75 mol%, at least 80 mol%, at least 85 mol%, at least 90 mol%, or at least 95 mol%, relative to the total moles of the ionic salt and the ZIPC compound combined.

[0140] The preferred electrolyte composition of the invention has a viscosity of at least 10 -9 As measured by electrochemical impedance spectroscopy (EIS), in some embodiments, the ionic conductivity of the electrolyte composition is at least 10 -9 S / cm, at least 10 -8 S / cm, at least 10 -7 S / cm, at least 10 -6 S / cm, at least 10 -5 S / cm, at least 10 -4 S / cm, at least 10 -3 S / cm.

[0141] Electrochemical cells and applications - Described herein are the uses of ZIPC compounds / matrices or ZIPC compositions in applications requiring ion conduction, including electrochemical devices such as fuel cells, energy storage devices, supercapacitors, or dye-sensitized solar cells. Described herein are the uses of ZIPC compositions in applications requiring ion conduction, including electrochemical devices such as fuel cells, energy storage devices, supercapacitors, or dye-sensitized solar cells.

[0142] Electrolytes are described herein that include one or more ZIPC compounds of the present invention as a matrix or as an additive to the electrolyte and / or one or more ZIPC compositions / composites according to the present invention as an electrolyte. Preferably, the ZIPCs of the present invention can be used in electrochemical cells as an electrolyte matrix or as an additive in an electrolyte material. The electrolyte can be, for example, a solid electrolyte or a liquid electrolyte at room temperature.

[0143] Preferably, the electrochemical cell or device is an energy storage device such as a Na battery or a Li battery, in particular a rechargeable or secondary battery. The materials described herein are particularly suitable for use with high voltage chemistries, such as Li / Li + Batteries containing materials exceeding 4.5V. Fuel cell devices comprising a zwitterionic plastic crystal (ZIPC) electrolyte matrix, optionally doped with an acid, base, or salt dopant, are described herein. Use of the protonated form of the zwitterionic plastic crystal (ZIPC) in applications requiring proton conduction, including fuel cells, is described herein. Base-doped ZIPC compositions can be used as an anhydrous proton conductor, preferably where the base is imidazole.

[0144] Desirably, the present invention provides an energy storage device comprising a negative electrode, a positive electrode, and an electrolyte, wherein the electrolyte comprises a ZIPC compound according to the present invention as a matrix or additive or a ZIPC electrolyte composition / composite.

[0145] definition - As used herein, the term "alkyl" describes a group consisting of at least one carbon atom and a hydrogen atom and represents a straight chain, branched chain or cyclic alkyl group, such as C 1-20 Alkyl groups, such as C 1-10 or C 1-6Examples of straight-chain and branched alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, 1,2-dimethylpropyl, 1,1-dimethyl-propyl, hexyl, 4-methylpentyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 1,1-dimethylbutyl, 2,2-dimethylbutyl, 3,3-dimethylbutyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl, 1,2,2-trimethylpropyl, 1,1,2-trimethylbutyl, propyl, heptyl, 5-methylhexyl, 1-methylhexyl, 2,2-dimethylpentyl, 3,3-dimethylpentyl, 4,4-dimethylpentyl, 1,2-dimethylpentyl, 1,3-dimethylpentyl, 1,4-dimethylpentyl, 1,2,3-trimethylbutyl, 1,1,2-trimethylbutyl, 1,1,3-trimethylbutyl, octyl, 6-methylheptyl, 1-methylheptyl, 1,1,3,3-tetramethylbutyl, nonyl, 1-, 2-, 3-, 4-, 5- , 6- or 7-methyloctyl, 1-, 2-, 3-, 4- or 5-ethylheptyl, 1-, 2- or 3-propylhexyl, decyl, 1-, 2-, 3-, 4-, 5-, 6-, 7- and 8-methylnonyl, 1-, 2-, 3-, 4-, 5- or 6-ethyloctyl, 1-, 2-, 3- or 4-propylheptyl, undecyl, 1-, 2-, 3-, 4-, 5-, 6-, 7-, 8- or 9-methyldecyl, 1-, 2-, 3-, 4-, 5-, 6- or 7-ethylnonyl, 1-, 2-, 3-, 4- or 5-propyloctyl, 1-, 2- or 3-butylheptyl, 1-pentylhexyl, dodecyl, 1-, 2-, 3-, 4-, 5-, 6-, 7-, 8-, 9- or 10-methylundecyl, 1-, 2-, 3-, 4-, 5-, 6-, 7- or 8-ethyldecyl, 1-, 2-, 3-, 4-, 5- or 6-propylnonyl, 1-, 2-, 3- or 4-butyloctyl, 1-2-pentylheptyl, etc. Examples of cyclic alkyl groups include monocyclic or polycyclic alkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, etc. When alkyl groups are generally referred to as "propyl", "butyl", etc., it will be understood that this refers to any suitable linear, branched, and cyclic isomers. Alkyl groups may be optionally substituted with one or more substituents, as defined herein, including substituents wherein a carbon is replaced with a heteroatom (eg, O, N, S).

[0146] Examples of optional substituents include alkyl (e.g., C 1-6 alkyl (e.g., methyl, ethyl, propyl, butyl, cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl), hydroxyalkyl (e.g., hydroxymethyl, hydroxyethyl, hydroxypropyl), alkoxyalkyl (e.g., methoxymethyl, methoxyethyl, methoxypropyl, ethoxymethyl, ethoxyethyl, ethoxypropyl, etc.), alkoxy (e.g., C 1-6Alkoxy such as methoxy, ethoxy, propoxy, butoxy, cyclopropyloxy, cyclobutyloxy), halogen, trifluoromethyl, trichloromethyl, tribromomethyl, hydroxy, phenyl (which itself may be replaced by, for example, C 1-6 Alkyl, halogen, hydroxyl, hydroxyl C 1-6 Alkyl, C 1-6 Alkoxy, halogenated C 1-6 Alkyl, cyano, nitro, OC(O)C 1-6 alkyl and amino), benzyl (wherein the benzyl group itself may be substituted by, for example, C 1-6 Alkyl, halogen, hydroxyl, hydroxyl C 1-6 Alkyl, C 1-6 Alkoxy, halogenated C 1-6 Alkyl, cyano, nitro, OC(O)C 1-6 alkyl and amino), phenoxy (wherein the phenyl group itself may be substituted by, for example, C 1-6 Alkyl, halogen, hydroxyl, hydroxyl C 1-6 Alkyl, C 1-6 Alkoxy, halogenated C 1-6 Alkyl, cyano, nitro, OC(O)C 1-6 alkyl and amino), benzyloxy (wherein the benzyl group itself may be substituted by, for example, C 1-6 Alkyl, halogen, hydroxyl, hydroxyl C 1-6 Alkyl, C 1-6 Alkoxy, halogenated C 1-6 Alkyl, cyano, nitro, OC(O)C 1-6 Alkyl and amino further substituted), amino, alkylamino (e.g. C 1-6 Alkyl groups such as methylamino, ethylamino, propylamino, etc.), dialkylamino groups (such as C 1-6 Alkyl groups such as dimethylamino, diethylamino, dipropylamino), amido groups (e.g. NHC(O)CH3), phenylamino groups (wherein the phenyl group itself may be replaced by groups such as C 1-6 Alkyl, halogen, hydroxyl, hydroxyl C 1-6 Alkyl, C 1-6 Alkoxy, halogenated C 1-6 Alkyl, cyano, nitro, OC(O)C 1-6 alkyl and amino groups), nitro, formyl, -C(O)-alkyl (e.g., C 1-6 Alkyl such as acetyl), OC(O)-alkyl (e.g. C 1-6 alkyl such as acetoxy), benzoyl (where the phenyl group itself may be replaced by, for example, C 1-6 Alkyl, halogen, hydroxyl, hydroxyl C 1-6 Alkyl, C 1-6 Alkoxy, halogenated C 1-6 Alkyl, cyano, nitro, OC(O)C 1-6Alkyl and amino further substituted), with C = O, CO2H, CO2 alkyl instead of CH2 (such as C 1-6 Alkyl groups such as methyl, ethyl, propyl, butyl), CO2 phenyl (wherein the phenyl group itself may be replaced by, for example, C 1-6 Alkyl, halogen, hydroxyl, hydroxyl C 1-6 Alkyl, C 1-6 Alkoxy, halogenated C 1-6 Alkyl, cyano, nitro, OC(O)C 1-6 alkyl and amino), CONH2, CONHphenyl (wherein the phenyl group itself may be substituted by, for example, C 1-6 Alkyl, halogen, hydroxyl, hydroxyl C 1-6 Alkyl, C 1-6 Alkoxy, halogenated C 1-6 Alkyl, cyano, nitro, OC(O)C 1-6 alkyl and amino), CONH benzyl (wherein the benzyl group itself may be replaced by, for example, C 1-6 Alkyl, halogen, hydroxyl, hydroxyl C 1-6 Alkyl, C 1-6 Alkoxy, halogenated C 1-6 Alkyl, cyano, nitro, OC(O)C 1-6 alkyl and amino further substituted), CONH alkyl (e.g. C 1-6 Alkyl such as methyl ester, ethyl ester, propyl ester, butyl amide), CONH dialkyl (such as C 1-6 alkyl), aminoalkyl (e.g. HNC 1-6 Alkyl-, C 1-6 Alkyl HN-C 1-6 Alkyl- and (C 1-6 alkyl)2N-C 1-6 Alkyl-), thioalkyl (such as HSC 1-6 alkyl-), carboxyalkyl (e.g. HO2CC 1-6 Alkyl-), carboxyl ester alkyl (e.g. C 1-6 Alkyl O2CC 1-6 alkyl-), amidoalkyl (e.g. H2N(O)CC 1-6 Alkyl-, H(C 1-6 alkyl)N(O)CC 1-6 alkyl-), formylalkyl (e.g. OHCC 1-6 Alkyl-), acylalkyl (e.g. C 1-6 Alkyl (O) CC 1-6 Alkyl-), nitroalkyl (e.g. O2NC 1-6 alkyl-), sulfoxide alkyl (such as R f (O)SC 1-6 Alkyl, wherein as defined herein, R fFor example, an alkyl group, such as C 1-6 Alkyl(O)SC 1-6 Alkyl-), sulfonylalkyl (e.g. Rf(O)2SC 1-6 Alkyl, wherein as defined herein, R f For example, an alkyl group, such as C 1-6 Alkyl (O) 2SC 1-6 alkyl-), sulfonylaminoalkyl (e.g. 2HR f N(O)SC 1-6 Alkyl, wherein as defined herein, R f For example, an alkyl group, such as H(C 1-6 alkyl)N(O)SC 1-6 alkyl-).

[0147] The term "halogen" ("halo") refers to fluorine, chlorine, bromine or iodine (fluoro, chloro, bromo or iodo). Preferred halogens are chlorine, bromine or iodine.

[0148] The heterocyclic group may be saturated or partially unsaturated, i.e., possess one or more double bonds. Particularly preferred heterocyclic groups are 5-6 and 9-10 membered heterocyclic groups. Examples of suitable heterocyclic groups may include aziridine, oxirane, thiirane, azetidinyl, oxetane, thietanyl, 2H-pyrrolyl, pyrrolidinyl, pyrrolinyl, piperidinyl, piperazinyl, morpholinyl, indolinyl, imidazolidinyl, imidazolinyl, pyrazolidinyl, thiomorpholinyl, dioxanyl, tetrahydrofuranyl, tetrahydropyranyl, tetrahydropyrrolyl, tetrahydrothiophenyl, pyrazolinyl, dioxolane, dioxolane, dioxolanyl ... The heterocyclyl group may be optionally substituted with one or more optional substituents as defined herein. The term "heterocyclylene" is intended to represent the divalent form of a heterocyclyl group.

[0149] The term "heteroaryl" includes any of monocyclic, polycyclic, fused or conjugated hydrocarbon residues in which one or more carbon atoms are replaced by heteroatoms to provide an aromatic residue. Preferred heteroaryl groups have 3-20 ring atoms, such as 3-10. Particularly preferred heteroaryl groups are 5-6 and 9-10 membered bicyclic ring systems. Suitable heteroatoms include O, N, S, P and Se, particularly O, N and S. Replacement of two or more carbon atoms may be by two or more of the same heteroatoms or by different heteroatoms. Examples of suitable heteroaryl groups may include pyridyl, pyrrolyl, thienyl, imidazolyl, furyl, benzothienyl, isobenzothienyl, benzofuranyl, isobenzofuranyl, indolyl, isoindolyl, pyrazolyl, pyrazinyl, pyrimidinyl, pyridazinyl, indolizinyl, quinolyl, isoquinolyl, phthalazinyl, 1,5-naphthyridinyl, quinoxalinyl, quinazolinyl, quinolyl, oxazolyl, thiazolyl, isothiazolyl, isoxazolyl, triazolyl, oxadiazolyl, oxatriazolyl, triazinyl and furazanyl. Heteroaryl may be optionally substituted with one or more optional substituents as defined herein. The term "heteroarylidene" is intended to represent a divalent form of a heteroaryl group.

[0150] The term "sulfoxide" refers either alone or in compound terms to a group R f -S(O)R f , wherein Rf is selected from hydrogen, alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclyl, carbocyclyl and aralkyl. f Examples include C 1-20 Alkyl, preferably C 1-6 Alkyl, most preferably C 1-3 Alkyl, phenyl and benzyl.

[0151] The term "sulfonyl" refers either alone or in compound terms to the group S(O)2-R f , where R f is selected from hydrogen, halogen, alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic, carbocyclic and aralkyl. Preferred examples of Rf include C 1-20 Alkyl, phenyl and benzyl.

[0152] The term "sulfonamide" refers either alone or in compound terms to the group S(O)NR f R f , wherein each Rf is independently selected from hydrogen, alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclyl, carbocyclyl and aralkyl. f Examples include C 1-20 In a preferred embodiment, at least one R f is hydrogen. In another form, two R f It's all hydrogen.

[0153] As used herein, the term "heteroatom" or "hetero" refers in its broadest sense to any atom other than a carbon atom that can be a component of a cyclic organic group. Examples of particular heteroatoms include nitrogen, oxygen, sulfur, phosphorus, boron, silicon, selenium, and tellurium, more particularly nitrogen, oxygen, and sulfur.

[0154] The present invention is described with reference to the following examples which are to be understood as illustrating but not limiting the invention described herein.

[0155] One of the compounds, ZIPC1 (with BF3 - The physical, thermal, and electrochemical properties of compound 1 (Figure 1) were compared with those of similar OIPCs (i.e., with separated cations and anions) to explore the advantages of connecting ionic species. This species was chosen as the similar OIPCs [C2mpyr][BF4] and [C2mpyr][NTf2] (Figure 1), which have demonstrated efficacy as electrolytes for lithium metal batteries.

[0156] It is expected that the use of sulfonimide groups, which are more charge-diffusive and hydrolytically stable, will replace the BF3 used in the first material. - Other cations, particularly morpholinium and piperidinium moieties ( FIG1 ), and ethyl-substituted pyrrolidiniums can be used within zwitterionic plastic crystals to prepare analogous structures of 8 and 9 with fluorosulfonyl imide groups ( FIG1 ), which are more favorable for reducing coordination with Li or Na salts and making the material more disordered.

[0157] Examples - Aprotic ZIPCs and Protic ZIPCs - Shown are a number of examples of zwitterionic plastic crystals (ZIPCs) compared to similar well-established OIPCs in Figure 1. To function as proton conductors, ZIPC compounds promote H + The conduction of ions (protons) while they themselves remain fixed as a matrix material. They are doped with acid or base. Base doping is preferred because it is more effective in proton conduction.

[0158]

[0159] To investigate the efficacy of these materials as lithium battery electrolytes, the zwitterionic ZIPC1 was combined with lithium salts, LiFSI or LiBF4, in the form of salt-doped ZIPC compositions. The salt-doped ZIPC compositions were investigated at concentrations of 10 mol% (Example 1) and 90 mol% (Example 2). Although the high lithium salt content introduces a large amount of free anions (FSI) that compete with the transference number of Li cations, the ZIPC compositions are not as effective as the ZIPC compositions of the present invention. - or BF4 - ), but high concentrations of Li ions can be very beneficial to device performance (e.g., by reducing polarization) and it is believed that ZIPC1 helps make Li +Dissociation from the respective counter anions leads to enhanced lithium ion transport compared to an equivalent high-Li salt content OIPC electrolyte. This demonstrates the general benefit of adding ZIPC, even when used as an additive in a small proportion of a conventional electrolyte mixture to promote the dissociation of the target ion. The ionic conductivity of pure ZIPC1 and [C2mpyr][BF4]OIPC and their equivalent mixtures with LiFSI as a function of temperature was studied and reported below.

[0160] As proof of concept for the electrolytes - preliminary DSC, NMR, conductivity, battery cycle and transfer numbers are available for many of these electrolytes. The tests and results are described in more detail below. In particular, the inventors investigated the following electrolytes:

[0161] 10 mol% LiFSI doped ZIPC1 electrolyte (Example 1): This is compared to 10 mol% LiFSI in a similar [C2mpyr][BF4]OIPC, which has been extensively studied previously in existing work by our research group to further demonstrate the advantages of linking cations and anions.

[0162] 90 mol% LiFSI-doped ZIPC electrolyte (Example 2): This is compared with pure ZIPC. Such high Li salt concentration may lead to good battery performance.

[0163] Proton ZIPC electrolyte (Example 3): To investigate the benefits of proton ZIPCs as anhydrous proton conductors, ZIPCs were doped with acids or bases.

[0164] ZIPC1 and its mixtures with 10 mol% and 90 mol% LiBF4 (Example 4): -DSC analysis ( Figure 16 a) shows that the melting transition temperature and melting entropy of 10 mol% LiBF4 in ZIPC1 are reduced compared to pure ZIPC1. This effect is also observed in mixtures of other plastic crystals with Li or Na salts and is attributed to the formation of eutectic compositions or the generation of more defects. When the LiBF4 concentration is increased to 90 mol%, a phase with a higher melting point (220°C) and a lower melting entropy (4.9 J / molK) is formed. SEM ( Figure 16 b) shows the morphology of 10 mol% LiBF4 in ZIPC1, which has grains connected by an amorphous or liquid-like phase that creates pathways that facilitate ion migration within the electrolyte. Figure 16 c) is significantly different, with more grains and grain boundaries, which indicates the plasticity of this solid electrolyte. Figure 16 d and 16e show the static solid-state of 10 mol% and 90 mol% LiBF4 in ZIPC1 7Li NMR spectra, which are measured in the temperature range of 20 to 60°C below the melting point. Generally, solid samples produce Li NMR spectra with broad line shapes due to strong homonuclear Li-Li interactions. 7 Li spectrum. However, the presence of mobile components due to increased disorder or the presence of an amorphous phase leads to a narrowed line shape. Single pulse of 10 mol% LiBF4 in ZIPC1 7 The Li spectrum shows narrow line shapes, which indicates that the dipolar interactions are well averaged. However, the 90 mol% LiBF4 in ZIPC1 7 The Li spectrum shows narrow components superimposed on broad components, which are attributed to the presence of mobile and less mobile Li ions, respectively. Figure 16 f and 16g show single pulse static of 10 mol% and 90 mol% LiBF4 in ZIPC1 19 F NMR spectrum from ZIPC1 19 The F peaks produce broad lines that are closely related to those from BF4 due to their close chemical shifts. - In both samples, the width of the broader component (which is relatively narrow compared to that expected for a fully ordered material) and the large number of narrow components suggest that BF4 - Anion and –BF3 on ZIPC1 - Due to the presence of higher concentration of charge carriers in the electrolyte, the ionic conductivity of the mixture with LiBF4 is about 3 orders of magnitude higher than that of pure ZIPC1 ( Figure 17 a). Pulsed field gradient (PFG) NMR measurements at different temperatures 7 Li and 19 The self-diffusion coefficient of F is Figure 17 b. In 10 mol% LiBF4 in ZIPC1, BF4 - Anion diffusion ratio 7 The diffusion of Li cations is faster. By increasing the salt concentration to 90 mol%, 7 Li cations become the fastest diffusing entities. This is expected to benefit the performance of electrolytes in lithium batteries. Cyclic voltammetry (CV) was used to study the compatibility and electrochemical stability of these new electrolytes with Li metal. Both 10 mol% and 90 mol% LiBF4 electrolytes in ZIPC1 showed stable cycling behavior, coupled with obvious Li deposition and precipitation peaks with small peak separation. This shows that this new class of electrolytes can support Li / Li + The rapid, stable and reversible reduction and oxidation reactions of α-HBr are carried out without a large number of additional side reactions. As expected from the low ion concentration in the electrolyte ( Figure 18), the peak current of the 10mol% LiBF4 sample is lower than that of the 90mol%. Thermal Studies - The thermal properties of pure ZIPC, various lithium-doped composites and proton ZIPC are given in Table 1. Table 1 describes the thermal properties of several ZIPCs, whereby the solid-solid phase transition (T s-s The presence of (below) is an evidence of potential structural disorder. Obviously, alkylation of the ring leads to T s-s The favorable reduction of T m remain above room temperature, which is important for their use as solid-state electrolytes.

[0165]

[0166] With BF3 - The ZIPC of the groups indicates the presence of solid-solid phase transitions in both compounds 1 and 2 (Figure 2, Table 1). This behavior is a key indicator of plasticity (when observed with at least one other characteristic indicator, such as from NMR or SEM), because these transitions represent the onset of disordering mechanisms (such as the rotation of specific functional groups), which is closely related to the formation of vacancies in the material and the improvement of electrical conductivity.

[0167] Figure 1B The DSC trace of ZIPC1 (C2mpyrBF3) in a shows the onset temperature and entropy change of each transition. As can be seen, the thermal analysis shows a clear solid-solid phase transition peak that distinguishes two solid phases before melting at 98 °C. The solid-solid phase transition of ZIPC1 shows 13 J mol -1 K -1 The entropy change of the melting transition is 21.4 JK. -1 mol -1 , which is close to the 20 J mol required by Timmerman's criterion for plastic crystallization behavior. -1 K -1 , indicating significant disorder in the material in Phase I (the highest temperature solid phase before melting).

[0168] Figure 1B The DSC trace of ZIPC2 is shown in b, along with the onset temperature and entropy change for each transition. As can be seen, ZIPC2 also exhibits a solid-solid phase transition, this time at 45°C. The presence of this phase transition represents the onset of molecular rotation within the material, which may result in disorder. Increasing the length of the alkyl chain substituents results in a decrease in the melting point from 98°C in ZIPC1 (C2mpyrBF3) to 60°C in ZIPC2 (C2epyrBF3).

[0169] For ZIPC6, Figure 1BThe DSC trace of ZIPC6 is shown in d, with the onset temperature and entropy change of each transition. The DSC trace of ZIPC6 shows a peak at 105°C. This sample was visually monitored at temperatures greater than 100°C (as can be seen in the figure). Figure 1B The peak at 105°C is not a melting transition, as the sample is solid even at 145°C. It is a solid-solid transition.

[0170] Each of ZIPC1, ZIPC2, ZIPC5, and ZIPC6 exhibits a solid-solid phase transition before melting. The presence of this transition and the low melting entropy of ZIPC1 are well-known characteristics of plastic crystal behavior. Typically, well-aligned crystalline organic salts have no solid-solid phase transition in the solid phase and have a ΔS m >60Jmol -1 K -1 . 1

[0171] Example 1 - Thermal Phase Behavior - 10 mol% LiFSI-doped ZIPC1 Electrolyte - The thermal phase behavior of ZIPC1 and 10 mol% LiFSI-doped ZIPC1 was compared with Figure 2A Comparison of the thermal phase behavior of pure [C2mpyr][BF4]OIPC and 10 mol% LiFSI doped [C2mpyr][BF4]OIPC. ZIPC1 shows a solid-solid phase transition (at 54 °C), which is an important characteristic of plastic crystal behavior. ZIPC has a melting onset at 98 °C, with a melting entropy ΔSf of 21.4 J K-1 mol-1. The ΔSf value is very close to the Timmermans criterion for plastic crystal behavior and is smaller than that of many known OIPCs. Similar OIPC [C2mpyr] [BF4] decomposes at 250 °C before melting. Therefore, thermal analysis (and NMR data described later) support the attribution of this new zwitterionic structure to a plastic crystal. Doping ZIPC1 with 10 mol% LiFSI reduces T m to 59°C, and small ΔS f 10J K -1 mol -1 A glass transition (Tg) was also observed at -66 °C, indicating the appearance of an amorphous phase in the mixture. Addition of 10 mol% LiFSI to [C2mpyr][BF4]OIPC introduced additional new peaks at temperatures lower than the phase IV to III transition (-95 °C and -70 °C) and also at 83 °C after the II-I transition, indicating the formation of a new phase at low temperatures ( Figure 2A(b)). The formation of a new phase after lithium salt addition has been observed previously in other pyrrolidinium-based OIPC-Li mixtures and is not unique to ZIPC. The initial evidence suggests that the material formed by the combination of OIPC and Li salt is a new, homogeneous solid, rather than a solid / liquid combination as formed with the ZIPC and salt combination. As a result, the slower Li phase formation in OIPC electrolytes is expected. + transport (because it moves through a solid rather than a liquid or amorphous phase), which is supported by the broader line widths seen in the NMR spectra discussed below (Figures 4 and 5).

[0172] Example 2 - Thermal Phase Behavior - 90 mol% LiFSI and ZIPC Electrolyte Mixture - The DSC heating traces of the electrolyte mixture of ZIPC1 and 90 mol% LiFSI in ZIPC1 are shown in Figure 2B. Adding only 10 mol% ZIPC1 to LiFSI reduces T m to 77° C. In addition, a glass transition (Tg) was also observed at −66° C., indicating the appearance of an amorphous phase.

[0173] SEM analysis - ZIPC1 - The SEM image of ZIPC1 shows slip steps and / or glide planes, which are commonly seen in OIPC due to its plastic nature but not in hard and brittle common organic / inorganic crystals such as sodium fluoride ( Figure 3D ). Because the SEM images were taken at room temperature, the material is expected to have increased plasticity at higher temperatures. 19 The F NMR spectra showed strong evidence of higher levels of plasticity at higher temperatures, as the line widths gradually narrowed and a narrow component appeared at 40°C and grew proportionally with increasing temperature. Together, these results suggest that ZIPC1 possesses intrinsic molecular rotational motion and forms a disordered phase within the ZIPC.

[0174] Furthermore, the microstructure / morphology of the surface of the ZIPC1 pellets shows evidence of plasticity, as multiple grains with different orientations can be observed. In addition, several sets of sliding planes within different grains can be seen. These sliding steps are also observed in the plastic OIPC system. Grain boundaries are clearly detected from the crushed surface of ZIPC6. The fact that the sliding steps maintain their coherency until they terminate at the grain boundaries also contributes to the plasticity. Considering that the SEM images were obtained at room temperature, which are Phase II (not the highest temperature solid phase) for both ZIPCs, this suggests that a higher level of plasticity will exist at higher temperatures. This is consistent with the discussion below that the plasticity increases with increasing temperature. 19 This is consistent with the slight increase in mobile components observed in FNMR measurements.

[0175] SEM analysis – Example 1 - 10 mol% LiFSI doped ZIPC1 electrolyte – in Figure 3A SEM analysis of pure ZIPC1 (10 mol% LiFSI in ZIPC1) is shown in Figure 3. The microstructure of the surface of the ZIPC1 pellet shows evidence of plasticity, as multiple grains with different orientations can be observed (Figure 3a). In addition, several sets of sliding planes can be seen within different grains. These sliding steps are also observed in the plastic OIPC system. The SEM image of 10 mol% LiFSI-doped ZIPC1 also shows that the particles in the ZIPC1 electrolyte are connected by a new, liquid-like phase (Figure 3b). Based on the NMR data (below), it is proposed that this phase has a high concentration of LiFSI. Therefore, it is believed that this phase provides a path for Li ion diffusion and promotes the transport of target ions through the electrolyte. The SEM image of this mixture also shows this and indicates that the particles in the ZIPC1 electrolyte are connected by this new, liquid-like phase. Based on the NMR data (below), it is believed that this phase has a high concentration of LiFSI. Therefore, this phase provides a path for Li ion diffusion and promotes the transport of target ions through the electrolyte.

[0176] SEM analysis - Example 2 - 90 mol% LiFSI and ZIPC electrolyte mixture - in Figure 3B An SEM image of the electrolyte mixture of 90 mol% LiFSI in ZIPC1 is shown in Figure 2. The SEM image of the electrolyte mixture of 90 mol% LiFSI in ZIPC1 shows crystalline and intergranular regions containing mobile, Li-rich electrolyte that provides pathways for lithium ions that support lithium electrochemistry and device cycling.

[0177] Example 3 - ZIPC5 and 10 mol% LiFSI in ZIPC5 - Static 1 H and 19 The F NMR spectrum shows evidence of disorder, as indicated by narrow line widths and an increasing proportion of narrow components. Narrow line widths exist even at 30°C, with disorder levels increasing at higher temperatures. This disorder (Figures 5D(a)-(c)) is consistent with the material being a plastic crystal. The DSC trace of pure ZIPC5 shows a broad peak near 25°C, which can be attributed to a solid-solid phase transition, and a sharp melting peak at 120°C. SEM images of ZIPC5 show grain boundaries, which can be evidence of plasticity, as these grain boundaries cannot be seen in fully ordered crystalline materials. The presence of grain boundaries in the ZIPC structure may aid ion conduction. All of these results show that ZIPC5 has a disordered structure consistent with the fact that it is a plastic crystal.

[0178] The solid-solid phase transition around 25°C is more obvious in the 10mol% LiFSI in ZIPC5 sample. Adding only 10mol% LiFSI to ZIPC5 lowers the melting point to 92°C. In addition, a glass transition (Tg) is observed at -29°C, indicating the appearance of an amorphous phase. SEM images of 10mol% LiFSI in ZIPC5 show a new amorphous phase, which can provide a path for Li ion diffusion and promote the transport of target ions through the electrolyte and will be very beneficial for the application of the material as an electrolyte in Li batteries. The ionic conductivity of 10mol% LiFSI in ZIPC5 shows a conductivity jump at 50°C, indicating higher mobility of Li and FSI ions after the solid-solid phase transition of ZIPC5 - similar behavior has been previously observed in other plastic crystalline materials. Because the ionic conductivity of pure ZIPC5 is not measurable, this ionic conductivity can be attributed to the mobility of FSI anions and Li cations.

[0179] Transport and Electrochemical Properties of ZIPC1 as Quasi-Solid-State Electrolytes - The electrochemical properties and interfacial behavior of novel ZIPC-containing electrolytes were evaluated based on: (i) voltammetric characterization of the behavior of three-electrode cells with Li metal as the working electrode, and (ii) galvanostatic and EIS characteristics of symmetric Li metal coin cells to demonstrate the applicability of these unique electrolyte materials. + The migration number measurements were performed electrochemically by chronoamperometry and compared with NMR results when applicable. Li+ Provides initial demonstration of the benefits of important zwitterions for improving target ion transmission.

[0180] Ionic Conductivity and NMR Linewidths - Example 1 - 10 mol% LiFSI Doped ZIPC1 Electrolyte - The ionic conductivity of the 10 mol% LiFSI doped [C2mpyr][BF4] electrolyte is approximately one order of magnitude higher than that of the ZIPC1 / LiFSI mixture (Figure 4A). This higher conductivity is expected because the OIPC-based electrolyte consists entirely of single ions, while in the ZIPC1 electrolyte 90% of the ionic components are connected and therefore cannot migrate in the electric field, leaving only Li and FSI ions mobile. Indeed, the fact that the conductivity of the ZIPC-based electrolyte is so close to that of OIPC is quite remarkable and points to the significant mobility of Li cations and FSI anions in the doped ZIPC host material. This was further analyzed by NMR, as discussed below.

[0181] Measurements of the line widths of static NMR spectra indicate the relative mobility of NMR active nuclei. Thus, even though OIPCs are solid materials, their intrinsic disorder (e.g., significant rotational motion of cations and / or anions) results in significantly narrow lines typically observed in crystalline solids. It should be noted that completely liquid samples produce very narrow lines because all substances are completely mobile, with translational and rotational motions. Significantly, the static NMR line widths of Li are much wider in 10 mol% LiFSI-doped [C2mpyr][BF4]OIPC electrolytes than in equivalent 10 mol% LiFSI-doped ZIPC1 electrolytes. Although, in general, OIPC-based electrolytes are more ionically conductive because they contain more free ions, the doped lithium ions are much less mobile than they are in salt-doped ZIPC1 electrolytes.

[0182] In contrast, the LiFSI-doped OIPC electrolyte 7 The Li spectrum shows a relatively broad single peak at 20°C, and a very small second narrow component appears at 30°C and increases very slightly at 60°C (Figure 5A(a)). This indicates that there is a very small proportion of diffused Li ions (although not enough to measure 7 Li diffusion coefficient). In contrast, the LiFSI-doped ZIPC electrolyte 7 The Li spectrum shows a single narrow signal (line width of about 0.3 kHz or less) for the entire temperature range and remains reasonably consistent with increasing temperature (Figure 5A(b)). This indicates that most of the Li ions in the LiFSI / ZIPC1 mixture are quite mobile, which is consistent with the assumption of a lithium-rich liquid-like phase in the LiFSI / ZIPC electrolyte. The Li line widths are much wider in the 10 mol% LiFSI-doped OIPC electrolyte than they are in the equivalent doped ZIPC1-based electrolyte (Figure 5A(c)). Therefore, although the OIPC-based electrolyte is more conductive overall because OIPC contains more free ions, the lithium ions appear to have much lower mobility than they do in the ZIPC1-based electrolyte.

[0183] This is also shown in Figure 5. 19 F NMR support. Briefly, the LiFSI-doped OIPC electrolyte at 20 °C 19 The F spectrum shows a broad peak for BF4 and a very small broad peak for FSI ions. However, at 60 °C, the spectrum shows two different BF4 environments, representing a relatively mobile component and a less mobile component. In contrast, the BF3 groups in the LiFSI-doped ZIPC1 electrolyte 19The F spectra show the presence of both mobile and less mobile components at all temperatures studied. In addition, the FSI anions in the LiFSI-doped ZIPC1 electrolyte 19 The F spectrum has only one narrow peak (i.e., representing one mobile component) over the entire temperature range examined. This indicates that almost all FSI anions are diffusive, which is supported by the measured FSI diffusion coefficient, which ranges from 3×10 -13 m 2 s -1 Increased to 4.6×10 -12 m 2 s -1 .

[0184] 10% LiFSI doped ZIPC1 electrolyte 1 The H spectra (not shown) also support the two-phase hypothesis. However, at all temperatures the spectra are dominated by narrow sharp lines, indicating that most of the cations are mobile, most likely in the liquid phase. In contrast, although the LiFSI-doped OIPC electrolyte mixture 1 The H spectrum also indicates the presence of cations with significant mobility, but they are present in a very low concentration, e.g., only a narrow 2% component at 40 °C, compared to 60% in the LiFSI-doped ZIPC1 electrolyte.

[0185] exist Figure 6a In the graph, it can be seen that the peak gradually narrows (smaller line width) from 21.5 kHz at 20°C to 14.1 kHz at 60°C as the temperature increases. This indicates more "mobility" of the -BF3 species (due to rotational disorder) as the material is heated. A second narrow peak (with a line width of approximately 1.2 kHz) above the initial broad peak becomes distinguishable from 40°C, indicating the presence of a small but proportionally increasing number of dynamic anions (in phase I) at higher temperatures ( Figure 6d -e). The presence of broad and narrow components is not unique to ZIPC, but is a clear indicator of disorder within the plastic crystal.

[0186] Ionic Conductivity and NMR Linewidth - Example 2 - 90 mol% LiFSI and ZIPC Electrolyte Mixture - The ionic conductivity of pure ZIPC1 and the electrolyte mixture of 90 mol% LiFSI in ZIPC1 is shown in Figure 4B as a function of temperature. Since both pure LiFSI and pure ZIPC have very low ionic conductivities, this result shows that the ionic conductivity of this mixture is significantly improved by adding only 10 mol% ZIPC1. The ionic conductivity of the electrolyte mixture of 90 mol% LiFSI and ZIPC1 is shown in Figure 5B. 7 Li spectrum, pure LiFSI 7Li spectrum and 90 mol% LiFSI and ZIPC1 electrolyte mixture 19 F spectra and 90 mol% LiFSI and ZIPC1 electrolyte mixture as a function of temperature 7 Li and 19 F line width. 90 mol% LiFSI and ZIPC1 mixture 7 The Li spectrum shows a single narrow signal (about 0.3 kHz or less) for the entire temperature range and remains reasonably consistent with increasing temperature (Figure 5B(a)). This indicates that most Li ions are quite mobile in this electrolyte. In contrast, the LiFSI of pure 7 The Li spectrum shows a broad single peak over the entire temperature range, indicating a rather low mobility (Figure 5B(b)). 19 The F spectrum has only one narrow peak (i.e., mobile component) over the entire temperature range ( FIG5B(c) ). This indicates that almost all FSI anions are diffusive, which is supported by the measured FSI diffusion coefficient. 7 Li and 19 The line width of both F and ZIPC1 is small in the 90 mol% LiFSI and ZIPC1 electrolyte mixture, indicating a relatively high mobility (Figure 5B(d)).

[0187] Diffusion coefficients - Example 1 - 10 mol% LiBF4 doped ZIPC1 electrolyte - Diffusion coefficients show that Li and FSI diffuse faster in LiFSI doped ZIPC1 electrolyte than in LiFSI doped OIPC electrolyte ( Figure 7A ). This is consistent with those anions being primarily in the liquid phase in the former. It is also important to note that only a small fraction of the ions are sufficiently mobile to be measured in the LiFSI-doped OIPC electrolyte, 19 F NMR measurements can only be made above 50°C. The diffusion coefficient indicates that Li diffusion is not measurable in the doped OIPC-based electrolyte even at temperatures as high as 60°C. Diffusion of FSI ions can only be measured above 50°C, consistent with the NMR line widths, which indicate that only a small fraction of FSI ions above 50°C are sufficiently mobile to diffuse in the doped OIPC electrolyte. The significantly higher diffusion rate in the LiFSI-doped ZIPC1 electrolyte clearly demonstrates the practicality of ZIPC for lithium battery applications, which is further explored below.

[0188] Diffusion coefficient - Example 2 - 90 mol% LiFSI and ZIPC1 electrolyte mixture - Figure 7B PFG-NMR measurements of 90 mol% LiFSI and ZIPC1 electrolyte mixtures at different temperatures.7 Li and 19 F diffusion coefficient. Diffusion coefficient is shown in 90 mol% LiFSI and ZIPC1 electrolyte mixture 7 Libby 19 F diffuses faster, which indicates that the Li transference number is high in this electrolyte.

[0189] Electrochemical Studies - Example 1 - 10 mol% LiFSI Doped ZIPC1 Electrolyte - Cyclic voltammetry (CV) was used to study the Li plating (negative scan) and precipitation (positive scan) behaviors of ZIPC1 electrolyte doped with 10 mol% LiFSI. CV data ( Figure 8 ) showed successful precipitation and plating of Li metal, and showed that this was stable and reversible, with the current density remaining stable during continuous cycling. The electrochemical stability of the electrolyte is an important factor in electrochemical devices. The results show that 10 mol% LiFSI doped ZIPC1 exhibited an anode limit of 5 V (relative to Li / Li+). It shows that this electrolyte has a wide enough electrochemical window to be used in batteries with high voltage cathode materials. In addition, this illustrates the ability of this electrolyte to support reversible precipitation and plating of Li / Li+ pairs. The electrochemistry is further examined below. Chronoamperometry of Li|10 mol% LiFSI doped ZIPC1 electrolyte|Li cell at 50°C with a potential step of 10 mV ( Figure 9A ). It was found that the lithium transfer number (t Li +) value is 0.3. These are for Li + It should be noted that it is not possible to measure t in 10 mol% LiFSI-doped OIPC. Li +.

[0190] Electrochemical Studies - Example 2 - 90 mol% LiFSI and ZIPC1 Electrolyte Mixture - Chronoamperometry studies of a Li|90 mol% LiFSI in ZIPC1 electrolyte mixture|Li cell at 50°C with a potential step of 10 mV are shown in FIG9B . The inset is the Nyquist plot of the electrochemical impedance spectroscopy response of the cell before polarization and after steady-state current. The lithium transference number (t Li +) value is 0.7. This is for Li + This is a remarkably high transference number for zwitterionic plastic crystalline compounds and demonstrates the promise of using them for electrolyte formation.

[0191] Cycling Studies - Example 1 - 10 mol% LiFSI-Doped ZIPC1 Electrolyte - The 10 mol% LiFSI-doped ZIPC1 electrolyte was then tested in a symmetric lithium metal cell (Figure 10A(a)). As expected, the polarization of the cell increased with increasing current density. However, the voltage curve was symmetric and reversible at all current densities. Therefore, the results indicate that the electrolyte is highly compatible with the reactive lithium electrode and can support Li ion transport even at 0.2 mAh cm -2 Figure 10 shows that even at a higher applied current density (0.2 mA cm -2 These results show that this electrolyte is a good candidate for use as an electrolyte for lithium batteries, supporting high-voltage electrochemistry of lithium and providing easy lithium ion transport; and b) ZIPC1 doped with 10 mol% LiFSI at 0.1 mA / cm 2 Symmetrical battery cycling performance at 50°C. The charge-discharge interval was kept at 1 hour. The inset is a zoom-in of the voltage curve at cycles 50-70. Thus, this electrolyte shows stable cycling over 100 cycles with low polarization potential. The electrolyte is stable even at 0.1 mA cm -2 The full cell consisting of a lithium metal anode and a lithium iron phosphate (LFP) cathode, LFP|10 mol% LiFSI in ZIPC1|Li was cycled at 50 °C in the range of 2.8 to 3.8 V (Figure 10A(b)). Figure 11 ). This battery exhibits stable long-term cycling at C / 20 at 50°C. The battery shows an increase in reversible capacity with cycling. It provides a reversible discharge capacity of 5 mAh / g in the first cycle and reaches a reversible discharge capacity of 24 mAh / g in the 70th cycle. It is speculated that the increase in reversible capacity may be the result of internal heating during cycling, which causes melting of the electrolyte near the electrode interface, resulting in better wetting of the electrode material with the electrolyte. After 30 cycles, a capacity retention of 90% was achieved, with a coulombic efficiency of 98%. These results show promising preliminary charge-discharge cycle performance of LFP|10 mol% LiFSI-doped ZIPC1 electrolyte|Li batteries at 50°C. The unoptimized battery shows significant efficiency (average efficiency of 98%), which is very important for battery performance.

[0192] Cycling studies – Example 2 - 90 mol% LiFSI and ZIPC electrolyte mixture - Figure 10BFigure 10(a)(c) illustrates the symmetrical cell cycling performance of a 90 mol% LiFSI and ZIPC1 electrolyte mixture at 0.1 mA / cm2 at 50°C. The charge-discharge interval was maintained at 1 hour. The inset of Figure 10(a)(c) is a zoom-in on the voltage curve at cycle 50-60. This electrolyte exhibits stable cycling for 480 cycles with low polarization potential.

[0193] Figure 12 The DSC trace of ZIPC7 shows three peaks during the heating cycle (T1 = 92 ° C; ΔHf = 26 J / g; T2 = 106 ° C; ΔHf = 10 J / g; T3 = 119 ° C; ΔHf = 25 J / g) (melting point of imidazole = 89 ° C); the DSC of a 50 / 50 mixture of ZIPC7 / imidazole shows a broad melting peak at 97 ° C, accompanied by a ΔHf of 1. f =25 J / g. This is different from the trace of pure ZIPC7, and there is no peak of pure imidazole (T m =89°C). Therefore, the altered melting behavior confirms the interaction between imidazole and zwitterion.

[0194] Figure 13 a) Conductivity of pure protic zwitterion ZIPC7 and when doped with imidazole base. The conductivity of each sample was measured in triplicate. Pure imidazole exhibited the lowest conductivity of all samples. In all cases, the conductivity increased with temperature. Adding a small amount of zwitterion (10%) to imidazole resulted in a 10-fold higher conductivity. The highest conductivity was achieved when 20% zwitterion was added to imidazole. In this case, the conductivity at room temperature was approximately 1000 times higher than that of pure imidazole. The conductivity of the 90 / 10 mixture was similar to that of the 50 / 50 mixture.

[0195] Proton ZIPC Electrolyte - To investigate the benefits of proton ZIPC as an anhydrous proton conductor, ZIPC was doped with acid or base. For example, ZIPC7 was doped with triflic acid. The conductivity after triflic acid doping was measured to be 10 -6 to 10 -5 S cm -1 The CV showed some electrochemical (H) activity which is important for fuel cell applications. However, doping with solid base imidazole seems more promising (see Figure 13 ) and this is summarized below. DSC of the 50 / 50 mixture (see Figure 12 ) shows a broad melting peak at 97°C with a ΔHf = 25 J / g. The sample appears different from the pure zwitterion, with only one peak present. The pure imidazole peak is also absent (Tm = 89°C). The altered melting behavior confirms an interaction between the imidazole and the zwitterion.

[0196] Comparison of conductivity using different combinations - pure imidazole showed the lowest conductivity among all samples ( Figure 13 The conductivity increases with temperature in all cases. Adding a small amount of zwitterionic ZIPC7 (10%) to imidazole increases the conductivity 10-fold (from 2.01×10 -7 S / cm to 10 -6 S / cm, Figure 13 The highest conductivity was obtained when 20% of zwitterionic ZIPC7 was added to imidazole ( Figure 13 In this case, the conductivity is already 2.23×10 -4 S / cm, which is about 1000 times higher than the conductivity of pure imidazole. The conductivity of the 90 / 10 mixture ( Figure 13 The middle group of circles) is similar to the 50 / 50 mixture (diamond group after the I:ZI 90:10 circle).

[0197] Thus, in summary, base-doped ZIPC7 shows much higher conductivity than pure imidazole (pure ZI is too low to measure). These conductivities are beneficial for solid-state, anhydrous proton conductors. Since pure imidazole is often used for proton conduction, this means that this proton ZIPC can provide significant improvements in proton conduction compared to pure imidazole.

[0198] Zwitterion-based liquid electrolytes - To explore the efficacy of using zwitterions as non-volatile mediators for high-target ion conduction in liquid electrolytes, high lithium salt content was used in conjunction with pyrrolidinium ZIPC1. When 50 mol% LiFSI was added to ZIPC1, only T g ( Figure 15 a inset) and the material is liquid at room temperature. Therefore, this zwitterion forms a high salt content liquid electrolyte. Zwitterion-based electrolytes are non-volatile and do not have competing cation migration. Existing work on developing zwitterionic liquids as electrolyte media has mainly used sulfonate or sulfonimide anions in combination with imidazolium cations, with the best results achieved using linkers with between five and seven CH2 groups. It is believed that the smaller size of the ZIPC1 molecule and the use of charge-diffusion BF3 - The structural part will enhance the conductivity and transference number. Indeed, the conductivity of the new material is 1.4×10 -4 S cm -1 (30℃)( Figure 15 a), which is the same as or higher than other reported liquid non-plastic zwitterionic electrolytes, and it also has a high migration number of 0.55±0.05 at 50°C.

[0199] The new zwitterionic liquid electrolyte also supports excellent stability for cycling lithium metal ( Figure 15 b) and is considered the first evidence of lithium metal cycling for liquid zwitterionic electrolytes. Five cycles were applied at each current up to 0.5 mA cm -2 Even at 0.5 mA cm -2 Under the condition of 0.05 mA cm, lithium deposition and plating also occurred with good stability and low polarization potential. Importantly, when the current density returned to 0.05 mA cm -2 At 0.2 mA cm -2 (0.2 mA h cm -2 This stability was also maintained over longer cycles under ). The overpotential remained low and stable at ~80 mV, even decreasing to ~70 mV after 65 cycles. This was attributed to the low internal resistance and consistent with the formation of a conductive SEI layer.

[0200] Synthesis of ZIPC3

[0201]

[0202] 1-(Chloromethyl)-1-methylpyrrolidin-1-ium iodide - 1-Methylpyrrolidine (1 equivalent) in ethyl acetate was reacted with chloroiodomethane (1 equivalent) and stirred at room temperature under an inert atmosphere for 16 hours. The ethyl acetate was then removed in vacuo and the solid washed with ether to give the product as a light brown solid (98% yield). 1 H NMR (run 07 / 02 / 2018) (400 MHz, CDCl3): 5.80 (s, 2H, NC H2 Cl), 4.15-4.21(m,2H,C H2 -5(Pyr)),3.88-3.93(m,2H,C H2 -2(Pyr)),3.50(s,3H,NC H3 ),2.32-2.45(m,4H,C H2 -3,4(Pyr)). 13 C NMR (run 12 / 03 / 2018) (100.6 MHz, CDCl3): 68.98, 64.35, 49.18, 22.37

[0203] 1-(Aminomethyl)-1-methylpyrrolidin-1-ium iodide - 1-(Chloromethyl)-1-methylpyrrolidin-1-ium iodide was reacted with aqueous ammonia solution (28%) and stirred at room temperature for 36 hours. The solvent was removed under vacuum, and the resulting residue was washed with dichloromethane and dried under vacuum to afford the target compound as a brown resin (~30% yield). 1H NMR (run 2 / 09 / 2019) (400 MHz, CDCl3): 5.61 (s, 2H, NC H2 NH2), 4.17-4.19(m,2H,C H2 -5(Pyr)),3.84-3.883.88-3.93(m,2H,C H2 -2(Pyr)),3.46(s,3H,NC H3 ),2.37-2.46(m,4H,C H2 -3,4(Pyr))

[0204] ((1-Methylpyrrolidin-1-ium-1-yl)methyl)((trifluoromethyl)sulfonyl)amide - 1-(Aminomethyl)-1-methylpyrrolidin-1-ium iodide (1 equiv) in dry acetonitrile was reacted with a solution of trifluoromethylsulfonyl chloride (1.5 equiv) in acetonitrile at ~0°C. The mixture was stirred at room temperature under an inert atmosphere for 4 days before being dried under vacuum. The resulting residue was purified with dichloromethane / water before being dried under vacuum to afford the title structure as a brown resin. 1 H NMR(19 / 12 / 19)(400MHz,CDCl3):5.44(s,2H,NC H2 NHS), 3.95-3.99(m,2H,C H2 -5(Pyr)),3.74-3.79(m,2H,C H2 -2(Pyr)),3.37(s,3H,NC H3 ),2.34-2.39(m,4H,C H2 -3,4(Pyr)). 19 F NMR(19 / 12 / 19)(376.5MHz, CDCl3):-78.60

[0205] Synthesis of ZIPC4

[0206]

[0207] 1-((Chlorosulfonyl)methyl)-1-methylpyrrolidin-1-ium chloride - N-Methylpyrrolidine (1 equivalent) in dry dimethylformamide was reacted with cold chloromethanesulfonyl chloride (1.2 equivalents), and the solution was stirred at room temperature under an inert atmosphere for 3 days. The product was then dried in vacuo and washed with diethyl ether to yield a black tar. Due to the sensitivity of the sulfonyl chloride moiety, the tar was immediately carried forward to the next step.

[0208] (((1-Methylpyrrolidin-1-ium-1-yl)methyl)sulfonyl)(2,2,2-trifluoroethyl)amide - 1-((chlorosulfonyl)methyl)-1-methylpyrrolidin-1-ium chloride (1 eq) in anhydrous dichloromethane was reacted with 1,1,1-trifluoroethylamine (1.2 eq) in a suspension of sodium bicarbonate (1.8 eq) and anhydrous dichloromethane. The reaction was stirred at room temperature under an inert atmosphere for 48 hours, after which the solids were filtered off and the filtrate organics removed under vacuum. The resulting residue was washed three times with diethyl ether and dried under vacuum to afford the target structure as a brown solid (~50% yield). 1 H NMR(6 / 8 / 2018)(400MHz,CDCl3):5.61(s,2H,NCH 2 SO2),4.34(s,2H,NC H2 CF3), 4.01-4.07(m,2H,C H2 -5(Pyr)),3.77-3.83 3.74-3.79(m,2H,C H2 -2(Pyr)),3.39(s,3H,NC H3 ),2.27-2.39(m,4H,C H2 -3,4(Pyr)). 19 F NMR(6 / 8 / 2018)(376.5MHz, CDCl3):-69.5

[0209] Electrochemical Impedance Spectroscopy (EIS) - The electrical conductivity of liquid and solid samples was measured following the procedure described by Makhlooghiazad et al., J. Mater. Chem. A, 2017, 5, 5770, section 2.2.2, the contents of which are incorporated herein by reference.

[0210] Solid-State Nuclear Magnetic Resonance Spectroscopy (NMR)— Solid-state NMR experiments were performed on a commercially available Bruker AVANCE III 500WB NMR spectrometer using a 2.5 mm zirconia rotor following standard procedures as described in Mater. Adv., 2021, 2, p. 1686, the contents of which are incorporated herein by reference.

[0211] Symmetric Cell Cycling - Li symmetric electrochemical coin cells were constructed to investigate the ability of the electrolyte to cycle Li metal with good efficiency without cracking using electrolytes composed of 10 mol% or 50 mol% LiFSI in ZIPC1. For each polarization, they were tested at 0.1 or 0.2 mA cm -2The cells were cycled at 50 ° C for 1 hour at a current density of 1.5 %. The cells were cycled galvanostatically using a Biologic VMP3 / Z potentiostat, and data were collected using EC-lab software version 11.27. The separator types used for battery cycling, migration number measurements, and full battery cycling are described in the text of the figure. The separators were dried under vacuum overnight and impregnated with a liquid electrolyte (50 mol% LiFSI in ZIPC1). For 10 mol% LiFSI in ZIPC1, the sample was melted at 90 ° C and the separator was then impregnated with the molten electrolyte; after the separator was fully wetted, the temperature was lowered to 50 ° C to solidify the electrolyte. These electrolytes were then sandwiched between two 8 mm diameter Li metal disks and assembled in a stainless steel battery case (Hohsen) using a 1 mm spacer and a 1.4 mm spring to provide uniform contact between the electrodes and the electrolyte inside the battery. Battery assembly was performed in an argon-filled glove box. The battery was stored at 50 ° C for 24 hours before cycling.

[0212] Cyclic voltammetry—Cyclic voltammetry (CV) was performed to investigate the redox behavior of Li in ZIPC1 with 10 mol% LiFSI. CV was performed with a two-electrode setup at 50 °C at 0.05 mV s -1 Scan rates of 1000 nm and 1000 nm were used using a Biologic VMP3 / Z potentiostat driven by EC-lab software. A glass fiber separator was impregnated with molten electrolyte and then sandwiched between a stainless steel working electrode and an 8 mm diameter lithium metal disk (Sigma Aldrich) serving as a reference / counter electrode, assembled into a stainless steel coin cell. All cell assembly procedures were performed in a glove box under an argon atmosphere.

[0213] Transfer Number - Li symmetric cells with 10 mol% and 50 mol% LiFSI in ZIPC1 were prepared using the same method as for the Li cycling test and the method described by Evans, Bruce, and Vincent was used to measure the Li transfer number at 50 °C. + Migration number. A small constant potential of 10 mV was applied to polarize the cell and the initial and steady-state currents were measured. Impedance spectra were obtained before and after polarization. To obtain reproducible and reliable values, multiple symmetrical cells were prepared. Cells showing a sharp increase in current or short circuits were discarded, and the reported results are the average of the others. All experiments were performed and impedance data were fitted using a VMP3 / Z Multi potentiostat (Bio-LogicScience Instruments) and EC-Lab software version 11.27.

[0214] Full Cell Cycling - The cycling performance of 10 mol% LiFSI in ZIPC1 was studied using a 2032 coin cell with a LiFePO4 (LFP) cathode and a Li metal disk (8 mm diameter) as the anode at 50°C using lower and upper cutoff voltages of 2.8 and 3.8 V, respectively. The LFP cathode was fabricated by mixing 80 wt% LFP powder, 10 wt% carbon black, and 10 wt% polyvinylidene fluoride (PVDF) in N-methylpyrrolidone (NMP). The prepared slurry was uniformly coated on an aluminum current collector and dried at room temperature overnight. The cathode electrode was further dried in a vacuum oven at 110°C for 16 h. The loading mass of active material in the electrode was ~1.8 mg cm -2 . The electrolyte was prepared using the same method as for the Li symmetric cycling test. The entire battery assembly process was performed in an argon-filled glove box. The battery was stored at 50°C for 24 hours before electrochemical testing to ensure complete absorption of the electrolyte into the electrodes. Constant current charge-discharge studies were performed inside an oven at 50°C using a Biologic VMP-3 battery test system.

Claims

1. A zwitterionic plastic crystal (ZIPC) compound selected from the group consisting of: 。 2. Use of the compound according to claim 1 as a solid solvent.

3. Use of the compound according to claim 1 as an electrolyte matrix.

4. Use of the compound according to claim 1 as a solid electrolyte matrix.

5. A zwitterionic plastic crystal composition in liquid or solid form comprising the zwitterionic plastic crystal (ZIPC) compound according to claim 1, and an ionic salt, an acid, a base, a Li or Na functionalized polymer, or a combination thereof.

6. The zwitterionic plastic crystal composition of claim 5, wherein ZIPC is present in a concentration of at least 5 mol%.

7. The zwitterionic plastic crystal composition according to claim 5, wherein the composition comprises an ionic salt selected from an alkali metal salt, an alkaline earth metal salt or a transition metal salt.

8. The zwitterionic plastic crystal composition according to claim 5, wherein the ionic salt is an alkali metal salt selected from the group consisting of LiBF4, LiFSI, LiNTf2, lithium bis(trifluoromethanesulfonyl)imide (Li[TFSI]), lithium bis(fluorosulfonyl)imide (Li[FSI]), lithium trifluoromethanesulfonate (Li[OTf]), lithium perchlorate (LiClO4), lithium dicyanamide (LiDCA), lithium cyanate (LiOCN), lithium bis[(pentafluoro-ethyl)sulfonyl]imide, lithium 2,2,2-trifluoromethylsulfonyl-N-cyanamide (TFSAM), lithium 2,2,2-trifluoro-N-(trifluoromethylsulfonyl)acetamide (TSAC), lithium nonafluorobutanesulfonate (NF), lithium carborane, and lithium difluoro(oxalato)borate.

9. An energy storage device comprising the zwitterionic plastic crystal (ZIPC) composition according to claim 5.

10. The energy storage device according to claim 9, wherein the energy storage device is a Na battery or a Li battery.

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