Nickel sulfide (NiS₂) is generally regarded as an appropriate anode for manufacturing new-type potassium-ion batteries (PIBs), while the development and application of NiS₂ are hampered by poor intrinsic electrical conductivity and huge volumetric change during potassiation/de-potassiation. Herein, we construct self-adaptive NiS₂ nanoparticles confined to a three-dimensional graphene oxide (NiS₂/3DGO) electrode via in situ sulfurization and self-assembly processes. The as-obtained NiS₂/3DGO exhibits high reversible capacity (391 mA h g⁻¹) and outstanding rate behavior (stable cycling at 1000 mA g⁻¹) for PIBs. Furthermore, in situ X-ray diffractometry and ex situ Raman test results elucidate partially reversible transformation from the cubic NiS₂ phase to the K_xNiS₂ intermediate, followed by generating a Ni⁰ and K₂S₄ product. This phenomenon is caused by the conversion reaction mechanism of NiS₂ 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.

中文翻译：

---

三维石墨烯负载的二硫化镍纳米粒子有望实现稳定快速的钾存储

硫化镍（NiS ₂）通常被认为是制造新型钾离子电池（PIBs）的合适阳极，而NiS ₂的开发和应用却受到了固有的电导率低以及在钾化/脱氢过程中体积变化大的阻碍。钾化。本文中，我们通过原位硫化和自组装过程构建了局限于三维氧化石墨烯（NiS ₂ / 3DGO）电极的自适应NiS ₂纳米颗粒。如此获得的NiS ₂ / 3DGO对PIB表现出高的可逆容量（391 mA hg ^-1）和出色的速率行为（在1000 mA g ^-1时稳定循环）。此外，原位X射线衍射和非原位拉曼试验结果阐明了从立方NiS ₂相到K _x NiS ₂中间体的部分可逆转变，然后生成了Ni ⁰和K ₂ S ₄产物。这种现象是由NiS ₂纳米晶体的转化反应机理以及初始循环中的非晶相变引起的。这样的理解可以为金属硫化物的应用提供新的思路，并为设计具有所需结构稳定性和寿命的新型电极提供指导。