Han Kang, Meng Jiashen, Hong Xufeng, Wang Xuanpeng, Mai Liqiang
School of Materials Science and Engineering, State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, 122 Luoshi Road, Wuhan, 430070, Hubei, China.
Nanoscale. 2020 Apr 21;12(15):8255-8261. doi: 10.1039/d0nr01274b. Epub 2020 Apr 3.
Nickel sulfide (NiS) is generally regarded as an appropriate anode for manufacturing new-type potassium-ion batteries (PIBs), while the development and application of NiS are hampered by poor intrinsic electrical conductivity and huge volumetric change during potassiation/de-potassiation. Herein, we construct self-adaptive NiS nanoparticles confined to a three-dimensional graphene oxide (NiS/3DGO) electrode via in situ sulfurization and self-assembly processes. The as-obtained NiS/3DGO exhibits high reversible capacity (391 mA h g) and outstanding rate behavior (stable cycling at 1000 mA g) for PIBs. Furthermore, in situ X-ray diffractometry and ex situ Raman test results elucidate partially reversible transformation from the cubic NiS phase to the KNiS intermediate, followed by generating a Ni and KS product. This phenomenon is caused by the conversion reaction mechanism of NiS nanocrystals along with an amorphous phase transition during the initial cycle. Such understandings may shed new light on the application of metal sulfides and give directions to design novel electrodes with desirable structural stability and lifespan.
硫化镍（NiS）通常被认为是制造新型钾离子电池（PIB）的合适阳极，然而，NiS的开发和应用受到其固有电导率差以及在钾化/去钾化过程中巨大的体积变化的阻碍。在此，我们通过原位硫化和自组装过程构建了一种自适应的、限制在三维氧化石墨烯中的硫化镍纳米颗粒（NiS/3DGO）电极。所制备的NiS/3DGO对PIB表现出高可逆容量（391 mA h g）和出色的倍率性能（在1000 mA g下稳定循环）。此外，原位X射线衍射和非原位拉曼测试结果表明，立方NiS相部分可逆地转变为KNiS中间体，随后生成Ni和KS产物。这种现象是由NiS纳米晶体在初始循环期间的转化反应机制以及非晶相转变引起的。这些认识可能为金属硫化物的应用提供新的思路，并为设计具有理想结构稳定性和寿命的新型电极指明方向。
