Scraps to superior anodes for Li-ion batteries: Sustainable and scalable upgrading of waste rust.

The abundant iron rust of no value generated from industrial scraps presents environmental problem and burden. Chemical etching and related methods deployed to convert rust into α-FeO nanoparticles, however, have serious shortcomings namely higher chemical consumption and generation of secondary pollution. In an unprecedented illustration, herein the intercalation of ammonium bicarbonate (ABC) as a gaseous bubble template into bulky iron rust is described; formation of ammonium iron carbonate hydroxide hydrate and the reduction of particle size using a simple ball milling method followed by calcination is accomplished. The salient features of ABC, optimization of ratios (rust: ABC), and the ideal calcination temperature were optimized for attaining desirable properties of meso-α-FeO NPs. The electrode obtained at 500 °C delivered a superior reversible capacity of 1,055 mAh g at 1 A g over 100 cycles, which is comparable to the best performance reported for meso-α-FeO NPs. The superior electrochemical performance is ascribed to the porous nature of meso-α-FeO NPs maximizing the surface area, ensuring good charge transfer kinetics and enhanced pseudocapacitive contribution. Thus, we believe that the high-energy ball milling (HEBM) process represents a novel route for the scalable recycling of iron rust scraps for promoting the sustainable production of lithium-ion batteries.