Recently, led by Professor Sun Lidong, School of Materials Science and Engineering, Chongqing University, Professor Ding Mei, and Professor Chuankun Jia from Changsha University of Science and Technology, a low-cost, high-performance perfluorosulfonic acid-based composite ion exchange membrane, Nafion / TiO2 nanotube composite membrane, has been developed. And applied to vanadium flow battery.
The super-hydrophilicity of TiO2 nanotubes makes it evenly dispersed in the Nafion matrix and exhibits a good effect of suppressing the penetration of vanadium ions. At a current density of 120 mA cm–2, the energy efficiency of the vanadium flow battery is as high as 84.4%, with a stable cycle of more than 1,400 cycles for more than 518 hours, which is much higher than the commercial Nafion membrane.
The relevant research results were published online in the "Advanced Energy Materials" journal of Wiley Press on March 29, 2020, with the title of Hybrid Membranes Dispersed with Superhydrophilic TiO2 Nanotubes Toward Ultra-Stable and High-Performance Vanadium Redox Flow Batteries.
Research premise
"Vanadium Flow Battery"
Vanadium flow battery is one of the most promising large-scale energy storage technologies at present. It can be used as an energy storage device for clean energy power generation and as an auxiliary method for peak shaving of the power grid to achieve safe and efficient operation of the power grid. As one of the key materials for flow batteries, ion exchange membrane determines the performance and cost of the battery; it isolates the positive and negative electrodes and the electrolyte to prevent short circuit of the electrode contact and cross-contamination of the electrolyte, while allowing balanced ions to freely pass through the separator Keep the overall battery neutral.
Research direction
"Improve the ion-selective performance of the diaphragm"
Morphology and structure of vanadium flow battery, TiO2 nanotube and Nafion / TiO2 nanotube composite film
At present, the ion selectivity of Nafion series diaphragms commonly used in vanadium flow batteries is low, which seriously affects the development of vanadium flow batteries. In this regard, the research team used electrochemical anodization to prepare TiO2 nanotubes, and used its super-hydrophilicity to regulate the Nafion membrane structure, reducing the use of polymers, and finally obtaining a high performance vanadium flow battery ion exchange membrane. This technology greatly improves the ion selection performance of the separator and reduces the cost of the separator, and has a wide range of application prospects.