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US-20260128340-A1 - TRANSPORT PROPERTY MODULATION VIA SOLVENT SPECIFIC BEHAVIOR IN CROSSLINKED NON-AQUEOUS MEMBRANES

US20260128340A1US 20260128340 A1US20260128340 A1US 20260128340A1US-20260128340-A1

Abstract

Nonaqueous redox flow batteries are one economically promising solution for meeting grid-scale energy storage needs at discharge durations of 10 h or more. However, membrane transport properties in nonaqueous systems are not as well understood as in water. Solvent-specific effects complicate efforts to understand transport in nonaqueous. In one aspect, the disclosure relates to blended cross-linked membranes compositions, methods of making same, and devices, products, and systems comprising same. In one aspect, the disclosed blended cross-linked membranes compositions comprise a cross-linked first polymer and a second polymer. The disclosed blends have desired permeabilities for selected cations and rejected undesired materials from the redox reaction mixture. This abstract is intended as a scanning tool for purposes of searching in the particular art and is not intended to be limiting of the present disclosure.

Inventors

  • Gary M. Koenig, JR.
  • Geoffrey M. Geise
  • Patrick M. McCormack

Assignees

  • UNIVERSITY OF VIRGINIA PATENT FOUNDATION

Dates

Publication Date
20260507
Application Date
20231014

Claims (20)

  1. 1 . A cross-linked blended membrane composition comprising: a blend of a first polymer and a second polymer, wherein the first polymer is a cross-linked polymer; and wherein the first polymer has a structure represented by a formula: wherein x has a value from about 0.2 to about 0.9; and wherein L is a structure represented by a formula selected from: wherein each of n and m is an integer independently selected from 0, 1, 2, and 3; wherein the second polymer has a structure represented by a formula: wherein y has a value from about 0.02 to about 0.6; and wherein X + is a cation selected from H + , an alkali metal cation, and combinations thereof.
  2. 2 . The cross-linked blended membrane composition of claim 1 , wherein L is a structure represented by a formula selected from:
  3. 3 . The cross-linked blended membrane composition of claim 2 , wherein L is a structure represented by a formula:
  4. 4 . The cross-linked blended membrane composition claim 3 , wherein each of n and m is an integer independently selected from 0, 1, and 2.
  5. 5 . (canceled)
  6. 6 . The cross-linked blended membrane composition claim 3 , wherein each of n and m is 0; and wherein L is a structure represented by a formula:
  7. 7 . The cross-linked blended membrane composition claim 1 , wherein X + is selected from H + , Li + , Na + , and K + .
  8. 8 .- 11 . (canceled)
  9. 12 . The cross-linked blended membrane composition of claim 1 , wherein y has a value from about 0.04 to about 0.4.
  10. 13 . The cross-linked blended membrane composition of claim 1 , wherein the first polymer is present in an amount of about 5 wt % to about 40 wt %; wherein the second polymer is present in an amount of about 95 wt % to about 60 wt %; wherein a total wt % is 100 wt %; and wherein the total wt % is based on a total weight of the first polymer and the second polymer.
  11. 14 .- 26 . (canceled)
  12. 27 . The cross-linked blended membrane composition of claim 1 , wherein the cross-linked blended membrane composition has a lithium-ion conductivity of greater than or equal to about 0.05 mS cm −1 where determined in accordance with the methods disclosed herein.
  13. 28 .- 38 . (canceled)
  14. 39 . A redox flow battery comprising: comprising the cross-linked blended membrane composition claim 1 ; a positive electrode; a positive electrolyte comprising a first redox active composition, wherein the positive electrolyte is in contact with the positive electrode; a negative electrode; and a negative electrolyte comprising a second redox active composition, wherein the negative electrode is in contact with the negative electrode, and wherein the cross-linked blended membrane composition is interposed between the positive electrode and the negative electrode.
  15. 40 . The redox flow battery of claim 0 , wherein the redox flow battery is a non-aqueous redox flow battery.
  16. 41 . The redox flow battery of claim 0 , wherein the positive electrode and the negative electrode independently comprise a metal, a carbon material, an electro-conductive polymer, and combinations thereof.
  17. 42 . The redox flow battery of claim 0 , wherein the positive electrolyte and the negative electrolyte each comprise a solvent independently selected from the group consisting of acetonitrile, dimethylacetamide, diethyl carbonate, dimethyl carbonate, γ-butyrolactone, propylene carbonate, ethylene carbonate, N-methyl-2-pyrrolidone, fluoroethylene carbonate, N,N-dimethylacetamide, and combinations thereof.
  18. 43 . The redox flow battery of claim 0 , wherein the positive electrolyte and the negative electrolyte each comprise the same solvent.
  19. 44 . The redox flow battery of claim 0 , wherein the positive electrolyte and the negative electrolyte each comprise a solvent independently selected from the group consisting of acetonitrile, dimethylacetamide, diethyl carbonate, dimethyl carbonate, and combinations thereof.
  20. 45 . The redox flow battery of claim 0 , wherein the solvent is dimethyl carbonate.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Application No. 63/416,409, filed on Oct. 14, 2022, which is incorporated herein by reference in its entirety. STATEMENT OF GOVERNMENT INTEREST This invention was made with government support 1940915 awarded by the National Science Foundation and DE-SC0022477 awarded by the Department of Energy. The government has certain rights in the invention. BACKGROUND The growing use of renewable, but nondispatchable, power sources like wind and solar has created a need for grid-scale energy storage with long discharge times (e.g., 10+ h) that currently are not common in grid-connected batteries. Redox flow batteries (RFBs) have been proposed as an option for grid-scale energy storage, but one limitation for current aqueous electrolyte-based RFBs is relatively low volumetric energy density, which results from the electrochemical stability window of water and active material solubility. Electrolytes prepared using organic solvents have a wider electrochemical stability window than aqueous electrolytes, and the chemistry of many organic redox active materials can be modified to enable very high solubility in organic solvents and higher energy density. While many parts of the RFB have an impact on the overall efficiency and power density of the battery, the separators in nonaqueous RFBs are a limiting factor because of the lack of purpose-engineered materials for this application. The separator must offer high ionic conductivity to provide high power density and voltage efficiency, and it must have low permeability of the dissolved active materials to prevent crossover that compromises battery longevity and/or coulombic efficiency. The properties of polymer ion exchange membrane (IEM) separators used with aqueous electrolytes have been extensively studied, but solvent-specific effects unique to nonaqueous systems are not yet fully understood. Changes in solvent can profoundly impact the solvent uptake of the polymer. For example, many membranes, which are dimensionally stable in water, may swell excessively or dissolve upon exposure to organic solvents. Even membranes that do not swell excessively can be subject to solvent-specific effects, which can lead to conductivity values much lower than expected based on solvent uptake and pure solution conductivity properties. Despite advances in RFB membrane research, there is still a scarcity of membrane materials that offer high ionic conductivity to provide high power density and voltage efficiency, that have low permeability of dissolved active materials to prevent crossover that can compromise battery longevity and/or coulombic efficiency. An ideal RFB membrane would allow ion selective flow while retaining non-desired ions, reactants, and other products from redox reactions and would function in an organic, non-aqueous liquid. These needs and other needs are satisfied by the present disclosure. SUMMARY In accordance with the purpose(s) of the disclosure, as embodied and broadly described herein, the disclosure, in one aspect, relates to blended cross-linked membranes compositions, methods of making same, and devices, products, and systems comprising same. Disclosed are cross-linked blended membrane compositions comprising: a blend of a first polymer and a second polymer, wherein the first polymer is a cross-linked polymer; and wherein the first polymer has a structure represented by a formula: wherein x has a value from about 0.2 to about 0.9; and wherein L is a structure represented by a formula selected from: wherein each of n and m is an integer independently selected from 0, 1, 2, and 3; wherein the second polymer has a structure represented by a formula: wherein y has a value from about 0.02 to about 0.6; and wherein X+ is a cation selected from H+, an alkali metal cation, and combinations thereof. Also disclosed are methods of making blended cross-linked membrane compositions, forming a pre-crosslinking mixture comprising a first polymer and a second polymer, wherein the first polymer has a structure represented by a formula: wherein x has a value from about 0.2 to about 0.9; wherein the second polymer has a structure represented by a formula: wherein y has a value from about 0.02 to about 0.6; and wherein X+ is a cation selected from H+, an alkali metal cation, and combinations thereof; forming a pre-crosslinked membrane from the pre-crosslinking mixture; drying the uncrosslinked membrane; pre-swelling the pre-crosslinked membrane with a swelling solution comprising a cross-linker and a first organic solvent, thereby forming a swollen pre-crosslinked membrane; and wherein the cross-linker is a structure represented by a formula selected from: wherein each of n and m is an integer independently selected from 0, 1, 2, and 3; initiating a cross-linking reaction in the swollen pre-crosslinked membrane by adding an initiator in a second organic solvent thereto, thereby forming