Ultrahigh Ion-Selective and Durable Nafion-NdZr Composite Layer Membranes for All-Vanadium Redox Flow Batteries

Abstract

A thin Nafion-neodymium zirconium oxide nanotube (NdZr) composite (Nafion-NdZr) membrane has been fabricated and further modified by the polycation, poly­(diallyldimethylammonium chloride) (PDDA), and polyanion, poly­(sodium styrene sulfonate) (PSS). The ion selectivity of the Nafion-NdZr (1%)/[P-S]2 composite layer membrane was found to be 6.9, 3.5, and 2.3 times higher than those of recast Nafion, Nafion/[P-S]2 layer, and Nafion-NdZr (1%) composite membranes, respectively. As a result, the vanadium redox flow batteries (VFBs) assembled with Nafion-NdZr (1%) composite and Nafion-NdZr (1%)/[P-S]2 composite layer membranes have surpassed the VFB performance operated with recast Nafion and Nafion/[P-S]2 layer membranes. Noticeably, VFB operated with the Nafion-NdZr (1%)/[P-S]2 composite layer membrane (513.7 h) exhibited a longer self-discharge time than those with Nafion-NdZr (1%) (293.2 h), Nafion/[P-S]2 (124.1 h), and recast Nafion (32.7 h) membranes. Finally, the single VFB cell constructed with Nafion-NdZr (1%)/[P-S]2 and Nafion-NdZr (1%) membranes remarkably showed 80.1 and 73.4% capacity retention, respectively, over 200 charge–discharge cycles, whereas recast Nafion exhibited a 41.5% capacity retention over 100 cycles at a 40 mA cm–2 current density. The structure and morphology of the Nd2Zr2O7 nanotube, Nafion-NdZr composite, and Nafion-NdZr (1%)/[P-S]2 composite layer membranes were investigated by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared, and atomic force microscopy analyses. Longer cyclic performance and excellent oxidative, chemical, and thermal stability further prove the durability of proposed membranes.

Ameliorated Performance of Sulfonated Poly(Arylene Ether Sulfone) Block Copolymers with Increased Hydrophilic Oligomer Ratio in Proton-Exchange Membrane Fuel Cells Operating at 80% Relative Humidity

“…Proton-exchange membranes (PEMs) are gaining great attention as both ion conductors and reactant separators for various energy storage/conversion devices such as fuel cells, solar cells and secondary batteries [ 1 , 2 , 3 , 4 ]. Among various fuel cells, proton-exchange membrane fuel cells (PEMFCs) have various inherent benefits such as high energy density and efficiency, trivial pollution contributions and quick startup times [ 5 ].…”

Designing Ion‐Selective Membranes for Vanadium Redox Flow Batteries

“…[87][88][89] It was shown that designing a "mixed-matrix membrane" is a promising approach for decreasing the methanol crossover problem. Since then, several studies were devoted to developing polymer-particle composite membranes for VRFBs based on both perfluorinated [90] and nonperfluorinated membranes [45,91] using either sol-gel or solution casting synthesis route.…”

“…In addition to oxide nanoparticles, double metal oxide of neodymium zirconium oxide nanotube (NdZr) was also evaluated to be used in a mixed matrix membrane leading to promising results ( Figure ). [ 90 ] However, overutilization of particles in the matrix membrane, which can act as physical barriers, is accompanied by reducing the proton conductivity and consequently lower Coulombic and energy efficiencies. On the other hand, it has been reported that the presence of hydrophilic particles like SiO 2 may also increase water uptake of the membrane, which enhances proton conductivity.…”

“…In this case, utilization of layer‐by‐layer membranes like Nafion–[PDDA–PSS] n for balancing the charges and “controlled Donnan effect” led to a relatively selective mechanism with additional “manipulated parameters” ( n = the number of layers). [ 90 ] Hossain et al. [ 90 ] developed a thin composite membrane by a two‐stage modification of Nafion, including i) incorporating Nd 2 Zr 2 O 7 into the Nafion ionomer using ethanol as a solvent to Nafion–NdZr membrane and ii) further modification by the polycation, poly(diallyldimethylammonium chloride) (PDDA), and polyanion, poly(sodium styrene sulfonate) (PSS) to LBL self‐assembled Nafion–NdZr (1%)/[P–S] 2 composite layer membrane.…”

“…[ 90 ] Hossain et al. [ 90 ] developed a thin composite membrane by a two‐stage modification of Nafion, including i) incorporating Nd 2 Zr 2 O 7 into the Nafion ionomer using ethanol as a solvent to Nafion–NdZr membrane and ii) further modification by the polycation, poly(diallyldimethylammonium chloride) (PDDA), and polyanion, poly(sodium styrene sulfonate) (PSS) to LBL self‐assembled Nafion–NdZr (1%)/[P–S] 2 composite layer membrane. The composite layer membrane showed 6.9, 3.5, and 2.3 time higher ion selectivity than Nafion, Nafion/[P–S] 2 layers, and Nafion–NdZr (1%) composite membranes, respectively.…”