Suppressing Crossover in Nonaqueous Redox Flow Batteries with Polyethylene-Based Anion-Exchange Membranes

Abstract

Redox flow batteries (RFBs) are a promising solution to grid-scale energy storage that utilize solvated redox-active species to store charge. These electrolytes are flowed over stationary electrodes during charge and discharge cycling. However, solubilizing the charge storage species allows for their crossover through the separating membrane, causing electrolyte mixing, and leads to capacity fade and battery failure. Herein, we employ a series of trimethylammonium-functionalized polyethylene membranes in RFB cells to address membrane swelling in organic solvent while maintaining high counterion (PF6 –) conduction. We show unprecedented results with 99.99% average capacity retention per cycle and 88% total capacity retention through 1000 charge/discharge cycles with low crossover, as compared to a commercial membrane often used in nonaqueous RFB (NARFB) studies which retained 36% capacity. Our results represent a critical step in developing and understanding anion-exchange membranes (AEMs) as separators for NARFBs and other electrochemical systems employing organic solvents.

Phenyl Acrylate-Based Cross-Linked Anion Exchange Membranes for Non-aqueous Redox Flow Batteries

“…All of the RFB experiments were carried out in an inert atmosphere glovebox (Ar, ≤0.5 ppm of O 2 and ≤0.5 ppm of H 2 O) by using a zero-gap flow cell as previously described in the literature. ,, The architecture of the flow cell device is described below. Polypropylene flow fields were sealed with Kalrez O-rings placed on two sides.…”

Recyclable and Degradable Ionic-Substituted Long-Chain Polyesters

“…The amount of ionic groups within the polymer can be varied over a broad range, higher concentrations being of interest with regard to proton or ion conductivity as polymer electrolytes, while low amounts of up to 10 mol % find applications in orthotics, prosthetics, as coatings of golf balls or as adhesives, to name a few. − An industrially relevant example is Surlyn, a copolymer of ethylene and methacrylic acid developed by DuPont . Both the amount of polar comonomer and the percentage of acid group neutralization allow for a fine-tuning of the polymer properties.…”

Direct Insertion Polymerization of Ionic Monomers: Rapid Production of Anion Exchange Membranes

“…[1] Furthermore, their self-healing, energy dispersive, shape-memory, stimuli-responsive, biocompatible, and antimicrobial properties have made them particularly attractive for use as biomimetic actuators and sensors, and as gene and drug delivery systems. [1][2][3] Importantly, ionic polymers and polyelectrolytes have especially proven useful as ion transport membranes for electrodialysis, [4] redox flow batteries, [5,6] water electrolysis, [7,8] and fuel cell devices. [9][10][11] Our research focuses on the latter of these applications, particularly in an effort to design and synthesize high performance anion exchange membranes (AEMs) for fuel cell and electrolyzer technologies.…”