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.

中文翻译：

---

混合膜用超亲水性TiO2纳米管分散成超稳定和高性能的钒氧化还原液流电池

钒氧化还原液流电池（VRFB）是一种大规模的储能技术，被认为是将间歇性可再生能源与电网整合的有希望的候选者。迄今为止，其长期稳定性一直受到核心成分（离子选择性低的离子交换膜）的限制。在此，报道了在Nafion基质中分散有超亲水性TiO ₂纳米管的杂化膜。具有混合膜的VRFB单电池在120 mA cm ^-2时表现出令人印象深刻的性能，具有高库仑效率（CE，≈98.3％）和出色的能量效率（EE，≈84.4％），比商品化的Nafion 212膜高（CE，≈94.5％； EE，≈79.2％）。更重要的是，该电池在1400个循环（超过518小时）后仍保持≈55.7％的放电容量，这与使用商用Nafion 212的电池仅进行410个循环后的≈20％的放电能量形成鲜明的对比。由于1）分散的纳米管引起的封闭和拉长的离子扩散途径，以及2）纳米管表面上磺酸基的结合和排列，对混合膜具有选择性。高性能膜在其他领域也可能找到重要应用，例如燃料电池，透析电池和水处理。