Hybrid Membranes Dispersed with Superhydrophilic TiO₂ Nanotubes Toward Ultra‐Stable and High‐Performance Vanadium Redox Flow Batteries

Abstract

The vanadium redox flow battery (VRFB) is a large‐scale energy storage technique and has been regarded as a promising candidate to integrate intermittent renewable energy with the grid. Its long‐term stability has so far been limited by the core component, an ion exchange membrane with low ion selectivity. Here a hybrid membrane with superhydrophilic TiO2 nanotubes dispersed in a Nafion matrix is reported. The VRFB single cell with the hybrid membrane exhibits an impressive performance with high coulombic efficiency (CE, ≈98.3%) and outstanding energy efficiency (EE, ≈84.4%) at 120 mA cm−2, which is higher than that of the commercial Nafion 212 membrane (CE, ≈94.5%; EE, ≈79.2%). More importantly, the cell maintains a discharge capacity of ≈55.7% after 1400 cycles (over 518 h), in obvious contrast to that of ≈20% after only 410 cycles for the one using commercial Nafion 212. This is attributed to the high ion selectivity of the hybrid membrane, because of, 1) the blocked and elongated ion diffusion pathway induced by the dispersed nanotubes and 2) binding and alignment of the sulfonic acid groups on nanotube surface. The high‐performance membranes may also find important applications in other fields, such as fuel cells, dialytic batteries, and water treatment.

Synergistic Catalysis of SnO2-CNTs Composite for VO2+/VO2+ and V2+/V3+ Redox Reactions

“…It is therefore necessary to develop a large-scale electric energy storage system to integrate renewable energy (Kou et al, 2020 ; Wang Z. et al, 2020 ). Vanadium redox flow batteries (VRFBs) have the merits of flexible design, short response time, and long cycle life, resulting in them becoming popular large-scale energy storage devices (Wu et al, 2016 ; Ye et al, 2020 ; Jiang et al, 2021a ).…”

Photocatalytic Hydrogen Generation from Water‐Annealed TiO2 Nanotubes with White and Grey Modification

“… [16–20] . The control of the nanotube morphology has widened the range of applications, such as for energy conversion, biochemical and medical devices [11,21–23] . Importantly, freshly formed, as‐anodized TiO 2 nanotube layers are amorphous – this is highly detrimental for any photoelectrochemical or photocatalytic applications.…”

“…[16][17][18][19][20] The control of the nanotube morphology has widened the range of applications, such as for energy conversion, biochemical and medical devices. [11,[21][22][23] Importantly, freshly formed, as-anodized TiO 2 nanotube layers are amorphous -this is highly detrimental for any photoelectrochemical or photocatalytic applications. Therefore, the amorphous tubes are usually thermally annealed in air or O 2 at temperature of 400-600°C to crystallize the amorphous phase into anatase.…”

Inhibition of Zinc Dendrites in Zinc-Based Flow Batteries

“…Flow batteries have received widespread attention due to their high safety and low cost (Liu et al, 2019a ; Zhang et al, 2019a ; Ye et al, 2020a , b ). Their power and capacity can be designed independently.…”