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Discovering cathode materials composed of earth-abundant elements has become the current priority for developing sodium-ion batteries (SIBs) to meet the ever-increasing demand of large-scale energy storage. Herein, for the first time, layered NaxMO2 (M = Cu, Fe, Mn) cathodes are successfully prepared by directly using concentrated chalcopyrite ores as precursors. Greatly, impurity elements like Si and Ca are found to be crucial to tailoring the phase structure of as-obtained layered oxides as a P2 or O3 type, which removes the traditional concern that the impurities may restrict the utilization of natural ores. More interestingly, a certain amount of the Ca elements remaining in the Na sites through a self-doping process endows the P2-type products with enhanced structural stability. In half-cells, P2-type NaxMO2 with self-doped Ca elements shows superior rate capability and cycling stability (56 mAh g-1 at 5 C and 90% capacity retention after 100 cycles at 1 C). In contrast, less impurity elements are favorable for O3-type oxides to achieve a high capacity of 107 mAh g-1 at 0.1 C and 84% capacity retention after 200 cycles at 2 C. This new strategy would efficiently shorten the process for preparing electrode materials and open a feasible route to construct cheap and durable SIBs.

Konjac glucomannan (KGM) featuring abundant oxygen functional groups has been elaborately designed to enhance Zn reversibility. Importantly, -OH and C[double bond, length as m-dash]O groups as active sites could redistribute the Zn2+ concentration field and modulate the plating/stripping rate, further enabling uniform Zn deposition without dendrite growth. The Zn@KGM anode enables an advanced Zn-ion supercapacitor to deliver an impressive rate performance and cycling stability (up to 5000 cycles accompanied by a coulombic efficiency of 99.8%).