Fluorine-Rich Covalent Organic Framework to Boost Electrochemical Kinetics and Storages of K+ Ions for Potassium-Ion Battery,Advanced Energy Materials

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Fluorine-Rich Covalent Organic Framework to Boost Electrochemical Kinetics and Storages of K+ Ions for Potassium-Ion Battery
Advanced Energy Materials ( IF 24.4 ) Pub Date : 2023-05-17 , DOI: 10.1002/aenm.202300442
Jiyoung Lee ₁ , Haeseong Lim ₁ , Junkil Park ₂ , Min‐Soo Kim ₁ , Ji‐Won Jung ₃ , Jihan Kim ₂ , Il‐Doo Kim ₁

Affiliation

Covalent organic frameworks (COFs), featuring ordered nanopores with numerous accessible redox sites, have drawn much attention as promising electrode materials for rechargeable batteries. Thus far, however, COF-based battery electrodes have exhibited limited capacity and unsatisfactory cycling stability due to the unwanted side reactions over their large surface area. Herein, a fluorine-rich covalent organic framework (F-COF) as an electrode material with improved stability and performance for potassium-ion batteries is developed. The fluorinated COF not only stabilizes intercalation kinetics of K⁺ ions but also reinforces its electron affinity and conductivity, improving the reversibility of bond transitions during discharge–charge cycles. As a result, F-COF affords a high specific capacity (95 mAh g⁻¹ at fast rates up to 5 C) and excellent cycling stability (5000 cycles with ≈99.7% capacity retention), outperforming the pristine COF-based electrodes devoid of F atoms. Notably, the experimental capacity of F-COF approaches its theoretical value, confirming that a large proportion of electroactive sites are being actively utilized. Altogether, this work addresses the significant role of F atoms in improving the K⁺-ion storage capability of COFs and provides the rational design principles for the continued development of stable and high-performance organic electrode materials for energy storage devices.

中文翻译：

富氟共价有机框架可促进钾离子电池的电化学动力学和 K+ 离子存储

共价有机框架（COF）具有有序的纳米孔和许多可接触的氧化还原位点，作为可充电电池的有前途的电极材料而引起了广泛关注。然而，迄今为止，由于COF基电池电极在其大表面积上发生不需要的副反应，其容量有限且循环稳定性不令人满意。在此，开发了一种富氟共价有机骨架（F-COF）作为钾离子电池的电极材料，具有改善的稳定性和性能。氟化COF不仅可以稳定K ⁺离子的嵌入动力学，还可以增强其电子亲和力和电导率，从而提高放电-充电循环期间键转变的可逆性。因此，F-COF 具有高比容量（95 mAh g^-1的快速速率高达 5 C）和出色的循环稳定性（5000 次循环，容量保持率约 99.7%），优于不含 F 原子的原始 COF 基电极。值得注意的是，F-COF的实验容量接近其理论值，证实很大一部分电活性位点正在被积极利用。总而言之，这项工作阐述了F原子在提高COF的K ⁺离子存储能力方面的重要作用，并为持续开发用于储能器件的稳定、高性能的有机电极材料提供了合理的设计原则。

更新日期：2023-05-17

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