US-12624163-B2 - Ionomers with macrocyclic moieties for ion conductivity and permselectivity

Abstract

Provided here are ion conducting materials including one or more macrocycles, and either one or more pendant groups or one or more backbone repeat units. The ion conducting materials exhibit distinctly high ion conductivity in thin film and bulk membrane applications, and further exhibit one or more of ion permselectivity, mechanical strength, self-assembly, stacking, and gating behavior. Further provided are methods for preparation and methods for use of the ion conducting materials.

Inventors

• Shudipto Konika Dishari

Assignees

• NUTECH VENTURES

Dates

Publication Date

20260512

Application Date

20210420

Claims (20)

1. 1 . An ion conducting material comprising: one or more macrocyclic repeat units, the macrocyclic repeat units comprising a macrocycle which is a calix[n]arene where n is an integer from about 4 to about 20, a crown ether, a cyclodextrin, or a porphyrin; a pendant group; and/or optionally one or more backbone repeat units, wherein the pendant group and the one or more backbone repeat units are chemically bonded to the macrocycle to form an ion conduction pathway of the ion conducting material, and wherein the pendant group, the one or more backbone repeat units, or both, comprise an ion conducting functional group to enable movement of ions through the ion conduction pathway of the ion conducting material.
2. 2 . The ion conducting material of claim 1 , further comprising a macrocycle which is a calix[n]arene where n is an integer from about 4 to about 20.
3. 3 . The ion conducting material of claim 1 , further comprising a macrocycle which is a dibenzo-x-crown-y ether, wherein x is a multiple of 3, ranging from 12 to 81, and y is x/3.
4. 4 . The ion conducting material of claim 3 , wherein the dibenzo-x-crown-y ether is one or more of dibenzo-18-crown-6, dibenzo-24-crown-8, and dibenzo-36-crown-12.
5. 5 . The ion conducting material of claim 1 , further comprising a macrocycle which is a cyclodextrin selected from α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin.
6. 6 . The ion conducting material of claim 1 , wherein the pendant group comprises an aliphatic group, and wherein the aliphatic group is alkyl, alkenyl, alkynyl, cycloalkyl, or heterocyclyl, each of which may optionally be substituted with one or more of alkyl, alkenyl, alkynyl, cycloalkyl, heterocycloalkyl, alkaryl, alkyl heteroaryl, amino, ammonium, acyl, acyloxy, acylamino, aminocarbonyl, alkoxycarbonyl, ureido, carbamate, aryl, heteroaryl, sulfinyl, sulfonyl, hydroxyl, alkoxy, sulfanyl, halo, carboxy, trihalomethyl, cyano, hydroxy, mercapto, or nitro.
7. 7 . The ion conducting material of claim 1 , wherein the pendant group comprises an aliphatic group, and wherein the aliphatic group is alkyl, perfluoroalkyl, or alkyl ether.
8. 8 . The ion conducting material of claim 1 , wherein the pendant group comprises an aromatic group, and wherein the aromatic group comprises aryl, heteroaryl, or aralkyl, each of which may optionally be substituted with one or more of alkyl, alkenyl, alkynyl, cycloalkyl, heterocycloalkyl, amino, ammonium, acyl, acyloxy, acylamino, aminocarbonyl, alkoxycarbonyl, ureido, carbamate, sulfinyl, sulfonyl, hydroxyl, alkoxy, sulfanyl, halo, carboxy, trihalomethyl, cyano, hydroxy, mercapto, or nitro.
9. 9 . The ion conducting material of claim 1 , wherein the pendant group comprises an aromatic group, and wherein the aromatic group comprises phenyl, biphenyl, triphenyl, naphthyl, or anthracenyl units.
10. 10 . The ion conducting material of claim 1 , wherein the pendant group comprises an aromatic group, and wherein the aromatic group comprises bisphenol, biphenyl, triphenyl, styrene, or fluorene, each of which may be optionally substituted with one or more of a sulfone, an ether sulfone, an ether ketone, or an ether ether ketone.
11. 11 . The ion conducting material of claim 1 , wherein the backbone repeat units comprise an aliphatic group, and wherein the aliphatic group is alkyl, alkenyl, alkynyl, cycloalkyl, or heterocyclyl, each of which may optionally be substituted with one or more of alkyl, alkenyl, alkynyl, cycloalkyl, heterocycloalkyl, aryl, alkaryl, alkyl heteroaryl, amino, ammonium, acyl, acyloxy, acylamino, aminocarbonyl, alkoxycarbonyl, ureido, carbamate, aryl, heteroaryl, sulfinyl, sulfonyl, hydroxyl, alkoxy, sulfanyl, halo, carboxy, trihalomethyl, cyano, hydroxy, mercapto, or nitro.
12. 12 . The ion conducting material of claim 1 , wherein the backbone repeat units comprise an aliphatic group, and wherein the aliphatic group is alkyl, perfluoroalkyl, or alkyl ether.
13. 13 . The ion conducting material of claim 1 , wherein the backbone repeat units comprise an aromatic group, and wherein the aromatic group is aryl, heteroaryl, or aralkyl, each of which may optionally be substituted with one or more of alkyl, alkenyl, alkynyl, aryl, cycloalkyl, heterocycloalkyl, amino, ammonium, acyl, acyloxy, acylamino, aminocarbonyl, alkoxycarbonyl, ureido, carbamate, sulfinyl, sulfonyl, hydroxyl, alkoxy, sulfanyl, halo, carboxy, trihalomethyl, cyano, hydroxy, mercapto, or nitro.
14. 14 . The ion conducting material of claim 1 , wherein the pendant group or backbone repeat units have a structure selected from the group consisting of: wherein R is an aliphatic and/or aromatic unit, and n is an integer from 1 to 10.
15. 15 . The ion conducting material of claim 1 , wherein the macrocycle has a structure selected from the group consisting of:
16. 16 . The ion conducting material of claim 1 , wherein macrocyclic moiety is gated.
17. 17 . An ion-conducting membrane comprising the ion conducting material of claim 1 .
18. 18 . The ion conducting material of claim 1 , wherein the ion conducting functional group comprises a sulfonic acid group, a sulfonate group, a quaternary ammonium group, or a phosphate group.
19. 19 . The ion conducting material of claim 1 , wherein the ion conducting material is a proton conducting material configured to receive water molecules at a first end of the ion conduction pathway of the proton conducting material and to provide protons from a second end of the ion conduction pathway of the proton conducting material.
20. 20 . The ion conducting material of claim 1 , wherein a sub-micron thick film of the ion conducting material has a proton conductivity of greater than or equal to 1×10 −3 mS/cm at a relative humidity of 25% or less.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application is a National Stage Entry of PCT Application of PCT/US2021/070432, filed on Apr. 20, 2021, titled “IONOMERS WITH MACROCYCLIC MOIETIES FOR ION CONDUCTIVITY AND PERMSELECTIVITY,” which claims the benefit of and priority to U.S. Provisional Application No. 63/012,462, filed on Apr. 20, 2020, titled “IONOMERS WITH MACROCYCLIC MOIETIES FOR ION CONDUCTIVITY AND PERMSELECTIVITY,” which is incorporated by reference herein in its entirety. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT This invention was made with government support under 1750040 and under 1557417 awarded by the National Science Foundation and under DE-SC0020336 awarded by the U.S. Department of Energy. The government has certain rights in the invention. TECHNICAL FIELD The present disclosure relates to ion conducting materials and their use in energy conversion and storage devices such as fuel cells and batteries. BACKGROUND To minimize the global carbon footprint, development of low-cost, eco-friendly electric cars and appliances are critical. However, the advancement of clean energy technologies relies on overcoming significant scientific challenges, including the development of next generation materials with improved performance and durability for use in energy conversion and storage devices such as fuel cells, batteries, electrolyzers, and supercapacitors. Electrochemistry is the core principle of all these energy conversion and storage devices, and ion conduction plays a critical role on the efficiency of these technologies. Proton exchange membrane fuel cell (PEMFC) is one such energy conversion device which requires proton conduction from anode to cathode, and can power not only the electric cars, but also unmanned vehicles, and many portable/stationary applications. PEMFC is eco-friendly as it does not produce any toxic or greenhouse gases (such as CO and CO2) while producing electricity, producing only water during oxygen reduction reaction at the cathode. However, one of the fundamental scientific and engineering challenges of fuel cells (including PEMFCs), electrolyzers, and many other energy technologies is the interfacial ion transport/conduction limitation. Such technologies require ion conducting polymers (or ionomers) in two different formats: (i) a bulk ion conducting polymer (several tens of micron thick) separating anode and cathode as well as preferentially transporting a specific type of cation or anion from one electrode compartment to another; and (ii) a sub-micron thickness (˜2-30 nm for Pt based catalysts) ionomer layer binding catalyst particles on the electrodes. This thin ionomer-based catalyst-binder layer is also expected to promote proton conduction to the catalyst interfaces. However, this nanoscale-thick film behaves very differently from a bulk membrane. In the nano-thin films, the entrapment of ionomer chains and water molecules (known as spatial confinement) as well as complex multimodal interfacial interactions among water, ionomer, and substrate impact the glass transition temperature (Tg) and often make water transport and ion conduction difficult. While the current state-of-the-art fluorocarbon-based and hydrocarbon-based ionomers conduct protons in bulk membrane efficiently, proton conduction through the thin films of the same ionomers is very poor. In sub-micron thick films of the current state-of-the-art ionomers (such as Nafion), the ionomer chains experience kinetic trapping and confinement. The phase mixing (rather than spontaneous phase segregation, needed for ion conduction) as well as small (˜1-2 nm in diameter), scattered, ill-connected ionic domains cannot conduct ions efficiently in thin films. Studies on Nafion, the current state-of-the-art fluorocarbon-based ionomer used for fuel cells, have shown that the activation energy of proton conduction in Nafion thin film is significantly higher than bulk Nafion membrane and the proton conductivity of thinner Nafion film is lower than bulk Nafion membrane. Nafion shows high proton conductivity (˜50-100 mS/cm) in bulk membrane (25-50 mm thick) format where the hydrophilic-hydrophobic phase separation leads to ionic domains with size ˜4 nm. The same ionomer, when spin-coated into several tens of nm thick films, forms ionic domains with narrower diameter. The number of proton conductive pathways and the connectivity of proton conducting domains decrease as the film thickness decreases. This resistance to ion conduction at ionomer binder-catalyst interfaces leads to sluggish electrochemical reaction (oxygen reduction reaction; ORR) kinetics and negatively impacts the power density and energy efficiency of energy conversion devices, such as PEMFCs. Ion conductivity of hydrocarbon-based ionomers are also very low in thin film (<1 μm) format due to high ion transport resistance as well as high phase mixing and narrow ion channels (in many cases). Accordingly, there is a need for ionomers