羟乙基-β-环糊精调控溴物种行为及其在高容量锌溴液流电池中的应用OA

Zinc-bromine flow batteries(ZBFBs)have been considered a promising long-duration energy storage technology owing to their high energy density(430 Wh/kg),abundant sources of electrolyte-active materials,and cost-effectiveness.However,electrolyte phase separation and the formation of reaction dead zones caused by the crossover of polybromide anions(Br2n+1-)in ZBFBs decrease battery capacity and lifespan.Herein,hydroxyethyl-β-cyclodextrin(HE-β-CD)is employed as a bromine-capturing agent.Its hydrophobic cavity can encapsulate polybromide anions,while its hydrophilic exterior maintains electrolyte homogeneity,thereby suppressing polybromide anion crossover.This strategy enables effective bromine electrolyte management and improves the performance of ZBFBs.The inclusion mechanism between HE-β-CD and polybromide anions is systematically investigated using density functional theory calculations,nuclear magnetic resonance spectroscopy,crossover tests,and electrochemical analyses.It is found that the"hydrophobic cavity capture"strategy enables the formation of large-volume inclusion complexes,which effectively suppresses polybromide anion crossover.When applied as a bromine-capturing agent in ZBFBs,only 0.05 mol/L HE-β-CD is required to achieve efficient capture of polybromide anions,delivering a Coulombic efficiency of 94.5％.The resulting flow battery achieves a discharge capacity of 30.4 Ah/L at 20％state of charge and exhibits excellent cycling stability,retaining 96.3％of its capacity after 300 cycles.This study provides an effective bromine management strategy for the development of high-capacity and stable ZBFBs.