Processing Rusty Metals into Versatile Prussian Blue for Sustainable Energy Storage

To reach a closed-loop material system and meet the urgent requirement of sustainable energy storage technologies, it is essential to incorporate efficient waste management into designing new energy storage materials. Here, we reported a “two birds with one stone” strategy to transform rusty iron products into Prussian blue as high-performance cathode materials and recover the rusty iron products to their original status. Owing to the high crystalline and Na⁺ content, the rusty iron derived Prussian blue shows a high specific capacity of 145 mAh g^{− 1} and excellent cycling stability over 3500 cycles. Through the in situ X-ray diffraction and in situ Raman spectra, it is found that the impressive ion storage capability and stability are greatly related to the suppressed structure distortion during the charge/discharge process. The ions migration mechanism and possibility as universal host of other kinds of ions are further illuminated by density functional theory calculations. This work provides a new strategy for recycling wasted materials into high value-added materials for sustainable battery systems, and is adaptable in the nanomedicine, catalysis, sensors, and gas storage applications.