湖南大学梁宵团队报道了氢键竞争实现摇椅式氟水离子电池。相关研究成果于2024年3月15日发表在国际知名学术期刊《德国应用化学》。

水性氟离子电池（FIBs）因其高理论能量密度而备受关注，但其受到缓慢的氟化动力学、活性材料溶解和电解质不稳定性的挑战。

该文中，研究人员提出了一种室温摇椅型水性FIBs，其为KOAc-KF二元盐电解质，能够在阴极和阳极同时进行氟化和脱氟反应。实验和理论结果表明，电解质中的乙酸根离子与氟离子在氢键形成中竞争，削弱了H₂O和F^-离子之间过强的溶剂化作用。这导致抑制了有害的HF形成，降低了F^-离子的去溶剂化能量，增强了电化学反应动力学。

铋基阴极在优化的电解质中能够直接转化，有效抑制了Bi²⁺中间体的有害歧化反应。此外，锌阳极经过典型的氟化过程，形成固体KZnF₃作为电极产品，将析氢风险降至最低。所提出的具有优化电解质的水性FIBs表现出高放电容量、长期循环稳定性和优异的倍率能力。

附：英文原文

Title: Rocking-Chair Aqueous Fluoride-ion Batteries Enabled by Hydrogen Bonding Competition

Author: Huijian Wang, Chengjun Lei, Tingting Liu, Chen Xu, Xin He, Xiao Liang

Issue&Volume: 2024-03-15

Abstract: Aqueous fluoride ion batteries (FIBs) have garnered attention for their high theoretical energy density, yet they are challenged by sluggish fluorination kinetics, active material dissolution, and electrolyte instability. Here, we present a room temperature rocking-chair aqueous FIBs featuring KOAc-KF binary salt electrolytes, enabling concurrent fluorination and defluorination reactions at both cathode and anode electrodes. Experimental and theoretical results reveal that acetate ions in the electrolyte compete with fluoride ions in hydrogen bonding formation, weakening the excessively strong solvation between H2O and F- ions. This results in the suppression of detrimental HF formation and a reduced desolvation energy of F- ions, enhancing the electrochemical reaction kinetics. The bismuth-based cathode exhibits direct conversion in the optimized electrolyte, effectively suppressing the detrimental disproportionation reactions from Bi2+ intermediates. Additionally, zinc anode undergoes a typical fluorination process, forming solid KZnF3 as the electrode product, minimizing the risks of hydrogen evolution. The proposed aqueous FIBs with the optimized electrolyte demonstrate high discharge capacity, long-term cycling stability and excellent rate capabilities.

DOI: 10.1002/anie.202401483

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202401483