One-pot spray pyrolysis method for nanostructured cobalt sulfide–C composite microspheres using recovered cobalt sulfuric acid solution and their excellent properties as anode materials for potassium-ion batteries

Abstract

To address the inherent limitations of metal sulfides, such as their restricted electrical conductivity and electrochemical stability, the construction of nanostructures within metal sulfide materials has garnered significant attention across diverse fields. To date, despite the reporting of various synthetic strategies for advanced metal sulfide nanostructures, there remains a pressing demand for the discovery of more efficient and cost-effective synthesis methods. In this study, a novel one-pot synthesis method for nanostructured cobalt sulfide microspheres is introduced using recovered cobalt sulfuric acid solution, obtained from waste material. To achieve complete sulfidation within a short reaction time and facilitate the uniform distribution of small-sized cobalt sulfide nanocrystals within the carbon matrix, sucrose as a key material is applied in the recovered solution. Furthermore, the addition of CNT components to the recovered solution, along with the various heteroatom doping induced by the recycling process, further inhibits the crystal growth of cobalt sulfides and enhances their electrochemical properties. Consequently, the developed cobalt sulfide–carbon–CNT composite microspheres exhibit remarkable cycling stability (retaining 405 mA g⁻¹ over 1000 cycles at 2 A g⁻¹) as well as excellent rate capability (253 mA h g⁻¹ at 5 A g⁻¹) as anode materials for potassium-ion batteries.