Bamboo-Like Hollow Tubes with MoS2/N-Doped-C Interfaces Boost Potassium-Ion Storage
Bamboo-Like Hollow Tubes with MoS2/N-Doped-C Interfaces Boost Potassium-Ion Storage
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具有MoS2/N-掺杂-C界面的竹类空心管可提高钾-离子存储
DOI：
10.1002/adfm.201803409
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发表时间：
2018-10-04
影响因子：
19
通讯作者：
Qu, Xuanhui
中科院分区：
文献类型：
--
作者：
Jia, Baorui;Yu, Qiyao;Qu, Xuanhui
钾离子电池（KIB）是一种新型的低成本二次电池，但由于大尺寸的钾离子导致电池动力学缓慢和循环过程中体积膨胀，导致电池的电化学性能较差。在这里，竹节状的MoS 2/N掺杂的-C空心管，具有10埃的扩展层间距离，作为KIB的高容量和稳定的阳极材料。除了内部圆柱中空空间之外，竹状结构还提供沿轴向方向的间隙沿着，以减轻径向和垂直方向上的应变，这最终导致用于稳定长期循环的高结构完整性。除了作为间层结构的组成部分之外，N-掺杂-C层编织笼以将钾化产物（多硫化物和Mo纳米颗粒）保持在一起，从而有效地阻碍固体电解质界面在颗粒内部的持续生长。密度泛函理论计算证明了MoS 2/N掺杂的C原子界面对K离子具有额外的吸引力。因此，其在低电流密度下提供高容量（50次循环后在50 mA g（-1）下为330 mAh g（-1）），并且在高电流密度下提供高容量保持率（1000次循环后在500 mA g（-1）下为151 mAh g（-1））。
Potassium-ion batteries (KIBs) are new-concept of low-cost secondary batteries, but the sluggish kinetics and huge volume expansion during cycling, both rooted in the size of large K ions, lead to poor electrochemical behavior. Here, a bamboo-like MoS2/N-doped-C hollow tubes are presented with an expanded interlayer distance of 10 angstrom as a high-capacity and stable anode material for KIBs. The bamboo-like structure provides gaps along axial direction in addition to inner cylinder hollow space to mitigate the strains in both radial and vertical directions that ultimately leads to a high structural integrity for stable long-term cycling. Apart from being a constituent of the interstratified structure the N-doped-C layers weave a cage to hold the potassiation products (polysulfide and the Mo nanoparticles) together, thereby effectively hindering the continuing growth of solid electrolyte interphase in the interior of particles. The density functional theory calculations prove that the MoS2/N-doped-C atomic interface can provide an additional attraction toward potassium ion. As a result, it delivers a high capacity at a low current density (330 mAh g(-1) at 50 mA g(-1) after 50 cycles) and a high-capacity retention at a high current density (151 mAh g(-1) at 500 mA g(-1) after 1000 cycles).