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

[Display omitted] •KOH-assisted aqueous strategy is provided to synthesize ZIF-67 polyhedrons.•Cobalt selenide/carbon composites with different crystal phases can be prepared controllably.•Co0.85Se/C composites as LIBs anode material exhibited excellent rate and cycling performances. 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.