微型多孔材料
材料科学
化学工程
介孔材料
纳米技术
碳纳米管
锂(药物)
共价有机骨架
多孔介质
多孔性
多硫化物
纳米管
化学
电极
有机化学
复合材料
电解质
催化作用
物理化学
内分泌学
工程类
医学
作者
JongTae Yoo,Sung Ju Cho,Gwan Yeong Jung,Su Hwan Kim,Keun Ho Choi,Jeong Hoon Kim,Chang Kee Lee,Sang Kyu Kwak,Sang Young Lee
出处
期刊:Nano Letters
[American Chemical Society]
日期:2016-04-28
卷期号:16 (5): 3292-3300
被引量:211
标识
DOI:10.1021/acs.nanolett.6b00870
摘要
The hierarchical porous structure has garnered considerable attention as a multiscale engineering strategy to bring unforeseen synergistic effects in a vast variety of functional materials. Here, we demonstrate a “microporous covalent organic framework (COF) net on mesoporous carbon nanotube (CNT) net” hybrid architecture as a new class of molecularly designed, hierarchical porous chemical trap for lithium polysulfides (Li2Sx) in Li–S batteries. As a proof of concept for the hybrid architecture, self-standing COF-net on CNT-net interlayers (called “NN interlayers”) are fabricated through CNT-templated in situ COF synthesis and then inserted between sulfur cathodes and separators. Two COFs with different micropore sizes (COF-1 (0.7 nm) and COF-5 (2.7 nm)) are chosen as model systems. The effects of the pore size and (boron-mediated) chemical affinity of microporous COF nets on Li2Sx adsorption phenomena are theoretically investigated through density functional theory calculations. Benefiting from the chemical/structural uniqueness, the NN interlayers effectively capture Li2Sx without impairing their ion/electron conduction. Notably, the COF-1 NN interlayer, driven by the well-designed microporous structure, allows for the selective deposition/dissolution (i.e., facile solid–liquid conversion) of electrically inert Li2S. As a consequence, the COF-1 NN interlayer provides a significant improvement in the electrochemical performance of Li–S cells (capacity retention after 300 cycles (at charge/discharge rate = 2.0 C/2.0 C) = 84% versus 15% for a control cell with no interlayer) that lies far beyond those accessible with conventional Li–S technologies.
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