Freestanding hollow double-shell Se@CNx nanobelts as large-capacity and high-rate cathodes for Li-Se batteries
Freestanding hollow double-shell Se@CNx nanobelts as large-capacity and high-rate cathodes for Li-Se batteries
复制标题
独立式空心双壳Se@CNx纳米带作为锂硒电池的大容量高倍率正极
DOI：
10.1016/j.nanoen.2016.12.010
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发表时间：
2017-02-01
期刊：
影响因子：
17.6
通讯作者：
Chu, Paul K.
中科院分区：
文献类型：
--
作者：
Cai, Qifa;Li, Yuanyuan;Chu, Paul K.
硒（Se）是一种很有前途的高能电池正极材料。然而，多硒化物穿梭效应和Se在循环时的大体积变化以及Se的差的离子和电子电导率破坏了其循环和速率性能。在本文中，我们报道了一种新型的基于Se的阴极材料，其中Se被完全封装并附着到中空核氮掺杂碳（CNx）纳米带的内壳，形成具有明确内部空隙体积的中空双壳Se@CNx纳米带。这种新型电极材料可以适应Se在循环时的大体积变化，并促进电子和离子转移，同时为Se和多硒化物中间体提供物理截留，从而产生大容量、高倍率性能和长寿命。具有62.5wt%的大Se含量和3.0mg cm（2）的面积质量负载，由相互缠绕和互穿的中空双壳层Se@ CN x纳米带组成的独立式和无粘合剂的Se@ CN x阴极可以在675 mA g（-1）的密度下提供608.8 mAh g（-1）的高容量并且循环稳定性保持超过400次循环，每次循环只有0.06%的容量衰减。当电流密度从80增加到1600 mA·g ~（-1）时，可逆容量保持率为70%。
Selenium (Se) is a promising cathode material in high-energy batteries. However, the polyselenides shuttle effect and large volume change of Se upon cycling as well as the poor ionic and electronic conductivity of Se undermine its cycling and rate performance. Herein, we report a novel Se-based cathode material in which Se is fully encapsulated and attached to the inner shell of hollow-core nitrogen-doped carbon (CNx) nanobelts forming hollow double-shell Se@CNx nanobelts with a well-defined inner-void volume. Such novel electrode material could accommodate the large volume variation of Se upon cycling and facilitate electron and ion transfer while providing a physical entrapment for the Se and polyselenide intermediates, thereby producing large capacity, high rate capability and long-lifespan. With a large Se content of 62.5 wt% and areal mass loading of 3.0 mg cm (2), the freestanding and binder-free Se@CNx cathode comprising of intertwining and interpenetrating hollow double-shell Se@CNx nanobelts could deliver a high capacity of 608.8 mAh g(-1) at a density of 675 mA g(-1) and the cycle stability is maintained for over 400 cycles with only 0.06% capacity decay per cycle. When the current density is increased 20 times from 80 to 1600 mA g(-1), 70% reversible capacity is retained.