Solution-phase selenization engineering of zeolitic imidazolate framework (ZIF)-67-derived Co_0.85Se@nitrogen-doped carbon for potassium-ion storage

Research on the synthesizing high-efficiency energy storage materials, which can the replace the harsh methods that require high temperature or high pressure, with methods that are more convenient and eco-friendly, are crucial for next-generation battery manufacturing. Herein, we introduce a facile method for the direct and short-term selenization of cobalt ions in zeolitic imidazolate framework-67 (ZIF-67) using a NaHSe solution. Co_0.85Se@nitrogen-doped carbon nanostructures (sol-CoSe@NC) obtained after the subsequent Ar heat treatment for the crystallization of Co–Se bonds and the carbonization of organic matter displayed outstanding electrochemical performances in potassium-ion batteries, compared to those fabricated by the well-known gas-phase selenization process. Long cycle life, over 140 cycles (367.7 mA h g⁻¹ at 0.1 A g⁻¹), and excellent rate capability up to 4.0 A g⁻¹ (202.9 mA h g⁻¹) of the sol-CoSe@NC electrode indicated that the ultrafine distribution of Co_0.85Se nanoparticles via a low-temperature and low-pressure solution-phase selenization process within the mesoporous structure derived from metal-organic framework could favorably work for the repeated insertion and desertion of potassium ions.