Han Kun, An Fuqiang, Wan Qi, Xing Lidong, Wang Lei, Liu Qiang, Wang Wei Alex, Liu Yongchang, Li Ping, Qu Xuanhui
Beijing Advanced Innovation Center for Materials Genome Engineering, Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing, 100083, P.R. China.
School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang, 621010, P.R. China.
Small. 2021 Mar;17(12):e2006719. doi: 10.1002/smll.202006719. Epub 2021 Mar 3.
The pyrrhotite Fe S with mixed Fe-valence possesses high theoretical capacity, high conductivity, low discharge/charge voltage plateaus, and superior redox reversibility but suffers from structural degradation upon (de)potassiation process due to severe volume variations. Herein, to conquer this issue, a novel hierarchical architecture of confining nano-Fe S in carbon nanotubes covalently bonded onto 3D few-layer graphene (Fe S @CNT@3DFG) is designed for potassium storage. Notably, CNTs could successfully grow on the surface of 3DFG via a tip-growth model under the catalytic effect of Fe C. Such structure enables the hierarchical confinement of 0D nano-Fe S to 1D CNTs and further 1D CNTs to 3DFG, effectively buffering the volume variations, prohibiting the agglomeration of Fe S nanograins, and boosting the ionic/electronic transportation through the stable and conductive CNTs-grafted 3DFG framework. The as-prepared Fe S @CNT@3DFG electrode delivers an exceptional rate capability (502 mAh g at 50 mA g with 277 mAh g at 1000 mA g ) and an excellent long-term cyclic stability up to 1300 cycles. Besides, the in-situ XRD and ex-situ XPS/HRTEM results first elucidate the highly reversible potassium-storage mechanism of Fe S . Furthermore, the designed potassium full-cell employing Fe S @CNT@3DFG anode and potassium Prussian blue (KPB) cathode delivers a promising energy density of ≈120 Wh kg , demonstrating great application prospects.
具有混合铁价态的磁黄铁矿FeS具有高理论容量、高导电性、低充放电电压平台和优异的氧化还原可逆性，但在（脱）钾过程中由于严重的体积变化而存在结构降解问题。在此，为了解决这个问题，设计了一种新颖的分级结构，即将纳米FeS共价键合在三维少层石墨烯上的碳纳米管中（FeS@CNT@3DFG）用于钾存储。值得注意的是，在FeC的催化作用下，碳纳米管可以通过尖端生长模型成功地生长在三维少层石墨烯的表面。这种结构能够将零维纳米FeS分级限制在一维碳纳米管中，进而将一维碳纳米管限制在三维少层石墨烯中，有效地缓冲体积变化，防止FeS纳米颗粒的团聚，并通过稳定且导电的碳纳米管接枝三维少层石墨烯框架促进离子/电子传输。所制备的FeS@CNT@3DFG电极具有出色的倍率性能（在50 mA g时为502 mAh g，在1000 mA g时为277 mAh g）以及高达1300次循环的优异长期循环稳定性。此外，原位XRD和非原位XPS/HRTEM结果首次阐明了FeS高度可逆的钾存储机制。此外，采用FeS@CNT@3DFG阳极和普鲁士蓝钾（KPB）阴极设计的钾全电池具有约120 Wh kg的有前景的能量密度，展示了巨大的应用前景。
