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Aqueous zinc-ion batteries (AZIBs) are regarded as alternative and promising large-scale energy storage systems due to their low cost, convenient manufacturing processes, and safety. However, their development has been restricted by the lack of suitable cathode materials. Here, we report an electrochemically-induced structure-reconstructed CaMn3O6@expanded graphite cathode with enhanced Zn storage performance. The restructured cathode exhibits abundant defects and phase interfaces, indicating higher electrochemical reactivity, larger active surface areas, accelerated ion diffusion kinetics, and superior structural robustness. Thus, the restructured cathode shows a high capacity (521.7 mA h g−1 at 0.2 A g−1), outstanding long-term stability (100% capacity retention after 2350 cycles at 2 A g−1, 75% after an additional 17 000 cycles at 5 A g−1), and superior rate performance. Deep and systematic investigation of the electrochemical mechanism using ex situ XRD, XPS, and TEM confirmed the co-insertion of both H+ and Zn2+. This work introduces a convenient and low-cost approach for promoting the Zn storage performance and new insights into the electrochemical mechanism of manganates for AZIBs. [ABSTRACT FROM AUTHOR]

Herein, we report a simple and quick synthetic route to prepare the pure CuFeS 2 quantum dots (QDs) @C composites with the unique structure of CuFeS 2 QDs encapsulated in the carbon frame. When tested as anode materials for the lithium ion battery, the CuFeS 2 QDs @C composites based electrodes exhibit excellent electrochemical performances. When charge-discharge occurred with a current density of 0.5 A g -1 , the electrodes exhibit a high reversible capacity (760 mA h g -1 ) for as long as 700 cycles, which indicates the superior cycling life. Detailed investigations of the morphological and structural changes of CuFeS 2 QDs by ex situ XRD, ex situ Raman, and ex situ TEM reveal an interesting electrochemical reaction mechanism, a hybrid of a lithium-copper iron sulfide battery and lithium-sulfur battery. The direct observation of orthorhombic FeS 2 by HRTEM and the existence of Li 2 FeS 2 detected by Raman support our assertion. We believe such an electrochemical mechanism would attract more attention to the CuFeS 2 nanomaterials as lithium ion battery anode materials. The excellent electrochemical properties would be derived from the unique structure, which include CuFeS 2 QDs encapsulated in the carbon frame.