Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore.
State Key Laboratory of Solidification Processing, Center for Nano Energy Materials, Northwestern Polytechnical University and Shaanxi Joint Laboratory of Graphene (NPU), Xi'an, 710072, P. R. China.
Adv Mater. 2019 Nov;31(48):e1905879. doi: 10.1002/adma.201905879. Epub 2019 Oct 14.
Covalent organic frameworks (COFs) are an emerging class of porous crystalline materials constructed from designer molecular building blocks that are linked and extended periodically via covalent bonds. Their high stability, open channels, and ease of functionalization suggest that they can function as a useful cathode material in reversible lithium batteries. Here, a COF constructed from hydrazone/hydrazide-containing molecular units, which shows good CO sequestration properties, is reported. The COF is hybridized to Ru-nanoparticle-coated carbon nanotubes, and the composite is found to function as highly efficient cathode in a Li-CO battery. The robust 1D channels in the COF serve as CO and lithium-ion-diffusion channels and improve the kinetics of electrochemical reactions. The COF-based Li-CO battery exhibits an ultrahigh capacity of 27 348 mAh g at a current density of 200 mA g , and a low cut-off overpotential of 1.24 V within a limiting capacity of 1000 mAh g . The rate performance of the battery is improved considerably with the use of the COF at the cathode, where the battery shows a slow decay of discharge voltage from a current density of 0.1 to 4 A g . The COF-based battery runs for 200 cycles when discharged/charged at a high current density of 1 A g .
共价有机骨架（COFs）是一类新兴的多孔晶体材料，由设计的分子构建块通过共价键周期性地连接和扩展而成。它们具有高稳定性、开放通道和易于功能化的特点，表明它们可以作为可逆锂电池中的有用阴极材料。本文报道了一种由含有腙/酰腙结构单元的分子单元构建的 COF，该 COF 具有良好的 CO2 捕获性能。将 COF 杂化到 Ru 纳米颗粒涂覆的碳纳米管上，发现该复合材料在 Li-CO 电池中作为高效阴极。COF 中的坚固一维通道作为 CO2 和锂离子扩散通道，提高了电化学反应的动力学。基于 COF 的 Li-CO 电池在 200 mA g 的电流密度下表现出超高的容量 27 348 mAh g-1，在 1000 mAh g-1 的限制容量内具有低截止过电势 1.24 V。在阴极使用 COF 可显著提高电池的倍率性能，电池在从 0.1 到 4 A g-1 的电流密度下放电电压缓慢衰减。在 1 A g-1 的高电流密度下放电/充电时，基于 COF 的电池可运行 200 个循环。
