Metal-Hydroxide Organic Frameworks for Aqueous Nickel-Zinc Batteries

Hydroxides exhibit a high theoretical capacity for energy storage by ion release and are often intercalated with anions to enhance the ion migration kinetics. In this study, a series of metal-hydroxide organic frameworks (MHOFs) are synthesized by intercalating aromatic organic linkers into hydroxides using I-M/Ni(OH)₂ (where M = Co²⁺, Cu²⁺, Mg²⁺, Fe²⁺). The coordination environment and layer spacing (1.09 nm) of I-M/Ni(OH)₂ are explored by X-ray absorption fine structure and cryo-electron microscopy. The intercalation nanostructure improves the conductivity of the hydroxides and facilitates Zn²⁺ migration by increasing the interlayer spacing, while enhancing the rate capability and cycling stability. Consequently, the I-Co/Ni(OH)₂ material exhibites a satisfactory specific capacity of 0.35 mAh cm^-2 at 3 mA cm^-2 and a high peak power density of 6.78 mW cm^-2. This study offers a novel perspective on the design of intercalated hydroxide and provides new insights into high-performance nickel-zinc batteres.