In this article, the novel concept of using magnetic nanofluidic electrolyte for redox flow batteries is demonstrated for the first time. In this regard, the stable magnetic nanofluidic electrolytes are prepared by dispersing magnetic modified multiwalled carbon nanotubes (MMWCNTs) in the positive electrolyte of a polysulfide-iodide redox flow battery at mass concentrations of less than 0.3 g L⁻¹. The electrochemical behavior of magnetic nanofluidic electrolyte was examined using cyclic voltammetry at different mass concentrations of MMWCNTs with a carbon felt electrode. Higher and stable peak current densities were observed at larger mass concentrations of MMWCNTs. A polysulfide-iodide redox flow battery was employed to evaluate the influence of magnetic nanofluidic electrolyte on the battery performance for various mass concentrations, velocities of flowing electrolyte, and current densities using electrochemical impedance spectroscopy, polarization, and galvanostatic charge-discharge experiments. A decrease in ohmic resistance as well as reductions in the charge-transfer and mass-transfer resistances were observed for the magnetic nanofluidic electrolyte compared to those obtained in the absence of MMWCNTs. Adding MMWCNTs to the positive electrolyte at the mass concentration of 0.3 g L⁻¹ results in enhanced performance of the polysulfide-iodide redox flow battery, whereby the peak power density increases by 45% and an energy efficiency of 79.91% was obtained at a current density of 20 mA cm⁻². Moreover, high coulombic efficiency close to 100% and stable cycling performance over 200 cycles were achieved using magnetic nanofluidic electrolyte. After 50 cycles, at a current density of 30 mA cm⁻², the energy efficiency of the battery operated with magnetic nanofluidic electrolyte remains 10% greater than that obtained in the absence of MMWCNTs. Besides improving the battery performance, MMWCNTs can be separated and recovered using magnetic decantation during electrolyte replacement for redox flow batteries involving high capacity fade and precipitation, which preserves system cost-benefits. The magnetic nanofluidic electrolyte could be applied for different redox solutions using appropriate magnetic nanoscale conductors. This innovative concept opens up a new opportunity to develop the next generation of high-performance and low-cost flow batteries.

在本文中，首次展示了将磁性纳米流体电解质用于氧化还原液流电池的新颖概念。在这方面，该稳定的磁纳米流体电解质通过在小于0.3克L-的质量浓度磁性改性多壁碳纳米管（MMWCNTs）在多硫化物-碘化物氧化还原液流电池的正极电解质分散制备^{- 1}。使用循环伏安法在具有碳毡电极的MMWCNT的不同质量浓度下检查了磁性纳米流体电解质的电化学行为。在较大的MMWCNT质量浓度下，观察到较高且稳定的峰值电流密度。使用电化学阻抗谱，极化和恒电流充放电实验，采用聚硫化物-碘化物氧化还原液流电池来评估磁性纳米流体电解质对各种质量浓度，流动电解质的速度和电流密度对电池性能的影响。与没有MMWCNT的情况相比，磁性纳米流体电解质的欧姆电阻降低，电荷转移和质量转移电阻降低。^{- 1周}的结果在多硫化物-碘化物氧化还原液流电池，由此以20mA cm 2的电流密度，得到了45％的峰值功率密度增大，并且79.91％的能量效率的提高的性能^-2。此外，使用磁性纳米流体电解质可实现接近100％的高库仑效率和超过200次循环的稳定循环性能。50次循环后，电流密度为30 mA cm ^-2，使用磁性纳米流体电解质运行的电池的能量效率仍然比没有MMWCNT的电池高10％。除了改善电池性能外，MMWCNTs还可在电解液更换过程中使用磁倾析法进行分离和回收，以用于涉及高容量褪色和沉淀的氧化还原液流电池，从而节省了系统成本。可以使用适当的磁性纳米尺度导体将磁性纳米流体电解质应用于不同的氧化还原溶液。这一创新理念为开发下一代高性能和低成本液流电池提供了新的机会。