Rechargeable aqueous zinc‐ion batteries (ZIBs) have been emerging as potential large‐scale energy storage devices due to their high energy density, low cost, high safety, and environmental friendliness. However, the commonly used cathode materials in ZIBs exhibit poor electrochemical performance, such as significant capacity fading during long‐term cycling and poor performance at high current rates, which significantly hinder the further development of ZIBs. Herein, a new and highly reversible Mn‐based cathode material with porous framework and N‐doping (MnOx@N‐C) is prepared through a metal–organic framework template strategy. Benefiting from the unique porous structure, conductive carbon network, and the synergetic effect of Zn2+ and Mn2+ in electrolyte, the MnOx@N‐C shows excellent cycling stability, good rate performance, and high reversibility for aqueous ZIBs. Specifically, it exhibits high capacity of 305 mAh g−1 after 600 cycles at 500 mA g−1 and maintains achievable capacity of 100 mAh g−1 at a quite high rate of 2000 mA g−1 with long‐term cycling of up to 1600 cycles, which are superior to most reported ZIB cathode materials. Furthermore, insight into the Zn‐storage mechanism in MnOx@N‐C is systematically studied and discussed via multiple analytical methods. This study opens new opportunities for designing low‐cost and high‐performance rechargeable aqueous ZIBs.

No abstract

In this study, a green process with prospective environmental and economic significance has been experimentally and theoretically established for the sustainable recovery of metals from spent lithium-ion batteries (LIBs). Three leaching systems were explored for the application of different biomass as reductants. According to leaching results, H3Cit (citric acid) and tea waste and H3Cit/H2O2 systems reveal similar leaching abilities (96% Co and 98% Li; 98% Co and 99% Li, respectively), while the H3Cit/Phytolacca Americana system shows inferior leaching performance (83% Co and 96% Li) under the optimized conditions. Tentative exploration of oxidation mechanism for different biomass indicates that potential reducing substances contained in biomass can be employed as efficient reductants during leaching. Then both metal ions and waste citric acid can be simultaneously recovered by selective precipitation. About 99% Co and 93% Li could be recovered as CoC2O4·2H2O and Li3PO4, and the recycled citric acid demonstrates similar leaching capability as fresh acid according to circulatory leaching experiments. Finally, solution chemistry theory and waste stream analysis were investigated to provide theoretical foundation for the recovery process.

No abstract

No abstract