KOH-assisted aqueous synthesis of ZIF-67 with high-yield and its derived cobalt selenide/carbon composites for high-performance Li-ion batteries

To solve the environmental pollution and low yield during the sythesis of zeolitic imidazolate frameworks (ZIFs) and their derived materials, a KOH-assisted aqueous strategy is proposed to synthesize cobalt zeolitic imidazolate framework (ZIF-67) polyhedrons, which are used as precursors to prepare cobalt selenide/carbon composites with different crystal phases (Co0.85Se, CoSe2). When evaluated as anode material for lithium ion batteries, Co0.85Se/C composites deliver a reversible capacity of 758.7 mA·h·g−1 with a capacity retention rate of 90.5% at 1.0 A·g−1 after 500 cycles, and the superior rate capability is 620 mA·h·g−1 at 2.0 A·g−1. The addition of KOH accelerates the production of ZIF-67 crystals by boosting deprotonation of dimethylimidazole, resulting in rapid growth and structures transition from two-dimensional to three-dimensional of ZIF-67 in aqueous solution, which greatly promotes the application of MOFs in the field of energy storage and conversion.