National & Local United Engineering Laboratory for Power Batteries, Faculty of Chemistry, Northeast Normal University, Changchun, Jilin 130024, P. R. China.
Nanoscale. 2018 May 17;10(19):9218-9225. doi: 10.1039/c7nr09674g.
In order to develop promising anode materials for sodium-ion batteries (SIBs), a novel pie-like FeS@C (P-FeS@C) nanohybrid, in which all ultrasmall FeS nanocrystals (NCs) are completely embedded into the carbon network and sealed by a protective carbon shell, has been prepared. The unique pie-like structure can effectively speed up the kinetics of electrode reactions, while the carbon shell stabilizes the FeS NCs inside. Studies show that the electrochemical reaction processes of P-FeS@C electrodes are dominated by the pseudocapacitive behavior, leading to an ultrafast Na+-insertion/extraction reaction. Hence, the prepared P-FeS@C nanohybrid exhibits superior Na-storage properties especially high rate capability in half cells. For example, it can deliver reversible capacities of 555.1 mA h g-1 at 0.2 A g-1 over 150 cycles and about 60.4 mA h g-1 at 80 A g-1 (an ultrahigh current density even higher than that of the capacitor test). Furthermore, an advanced P-FeS@C//Na3V2(PO4)2O2F full cell has been assembled out, which delivers a stable specific capacity of 441.2 mA h g-1 after 80 cycles at 0.5 A g-1 with a capacity retention of 91.8%.
为了开发有前景的钠离子电池 (SIBs) 用阳极材料，我们制备了一种新型派状 FeS@C (P-FeS@C) 纳米杂化材料，其中所有的超小 FeS 纳米晶 (NCs) 都完全嵌入碳网络中，并由保护性碳壳密封。独特的派状结构可以有效地加速电极反应动力学，而碳壳稳定了内部的 FeS NCs。研究表明，P-FeS@C 电极的电化学反应过程主要受赝电容行为的控制，导致超快 Na+-插入/提取反应。因此，所制备的 P-FeS@C 纳米杂化材料表现出优异的储钠性能，尤其是在半电池中具有高倍率性能。例如，在 0.2 A g-1 的电流密度下，经过 150 次循环后，其可逆容量可达到 555.1 mA h g-1，在 80 A g-1（甚至高于电容器测试的超高电流密度）时，可逆容量约为 60.4 mA h g-1。此外，组装了先进的 P-FeS@C//Na3V2(PO4)2O2F 全电池，在 0.5 A g-1 的电流密度下经过 80 次循环后，其稳定的比容量为 441.2 mA h g-1，容量保持率为 91.8%。
