Three-dimensional hierarchical C-Co-N/Se derived' from metal-organic framework as superior cathode for Li-Se batteries
Three-dimensional hierarchical C-Co-N/Se derived' from metal-organic framework as superior cathode for Li-Se batteries
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DOI：
10.1016/j.jpowsour.2017.07.065
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发表时间：
2017-09-30
影响因子：
9.2
通讯作者：
He, Weidong
中科院分区：
文献类型：
--
作者：
He, Jiarui;Lv, Weiqiang;He, Weidong
以金属有机骨架(MOF)为骨架，制备了钴氮共掺杂的三维多孔石墨炭(C-Co-N)，并将其作为Lewis碱基质负载Se。由于具有丰富的微/介孔的独特结构，高导电性的C-Co-N基质为电子转移和离子扩散提供了高效的通道，并提供了足够的比表面积来负载纳米硒，同时减缓了多硒的溶解和抑制了体积膨胀。在锂硒电池的运行过程中，钴纳米粒子和氮基在C-Co-N复合材料中的均匀分布通过强烈的化学作用固定了多硒化合物。在Se负载量为76.5wt%的情况下，C-Co-N/Se正极具有优异的电化学性能，其超高可逆容量为672.3 mAHg(-1)(理论值的99.6%)，200次循环后的容量为574.2 mAHg(-1)，容量衰减率仅为0.07%/次，哥伦布效率接近100%。用原位拉曼光谱和密度泛函理论模拟研究了电解液/阴极界面的Se(脱锂)机理，证实了C-Co-N支架的结构和组成为高性能的Se基阴极提供了有效的阴极基质，同时显著降低了容量衰减。(C)2017爱思唯尔B.V.保留所有权利。
Three-dimensional, porous graphitic carbon co-doped with cobalt and nitrogen (C-Co-N) is prepared with metal-organic framework (MOF) and employed as Lewis base matrix to host selenium. Owing to the unique structure with abundant micro/meso-pores, the highly-conductive C-Co-N matrix provides highly-efficient channels for electron transfer and ionic diffusion, and sufficient surface area for loading of selenium nanoparticles while mitigating dissolution of polyselenides and suppressing volume expansion. The homogenous distribution of cobalt nanoparticles and nitrogen-group in C-Co-N composite immobilize polyselenides through strong chemical interaction in the operation of Li-Se batteries. With a very high Se loading of 76.5 wt%, the C-Co-N/Se cathode delivers superior electrochemical performance with an ultrahigh reversible capacity of 672.3 mAh g(-1) (99.6% of the theoretical value) and a capacity of 574.2 mAh g(-1) after 200 cycles, giving a capacity fading of only 0.07% per cycle and a nearly 100% Columbic efficiency. In-situ Raman spectroscopy and density functional theory simulations are employed to investigate the Se (de)lithiation mechanism at the electrolyte/cathode interface, and confirm that the structure and composition of C-Co-N scaffold give rise to efficient cathode host for high-performance Se-based cathodes with dramatically reduced capacity fading. (C) 2017 Elsevier B.V. All rights reserved.