Realizing Fast Diffusion Kinetics Based on Three-Dimensional Ordered Macroporous Cu₉S₅@C for Potassium-Ion Batteries

Recently, potassium-ion batteries (PIBs) have been deemed to be a potential next-generation energy storage system for large-scale application because of the similar metal-ion storage mechanism as lithium-ion batteries and rich potassium resources. However, the large-sized potassium ion will cause sluggish reaction kinetics of K⁺ during charge/discharge processes, hindering the development of high-performance PIBs. In this work, copper sulfide embedded in three-dimensional ordered macroporous carbon framework (3DOM Cu₉S₅@C) was prepared through a sulfidation and subsequent ion exchange strategy with 3D ordered macropore Zn-based metal-organic frameworks as a precursor for an advanced PIBs anode. In particular, the interconnected 3D ordered macroporous structure can provide rapid transport channels for the large potassium ions and create a sufficient contact area for solid electrode materials and the liquid electrolyte, which is conducive to improve the ionic diffusion kinetics of batteries. Consequently, when the prepared 3DOM Cu₉S₅@C composite was used as a PIBs anode material, it shows a remarkable potassium storage rate capacity of 170 mA h g^-1 at 2.0 A g^-1 and an excellent cycling stability of 316 mA h g^-1 at 100 mA g^-1 after 200 cycles.