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High-potential Mn3+/Mn2+redox couple (>1.3 V vs SHE) in a static battery system is rarely reported due to the shuttle and disproportionation of Mn3+in aqueous solutions. Herein, based on reversible stripping/plating of the Sn anode and stabilized Mn2+/Mn3+redox couple in the cathode, an aqueous Sn–Mn full battery is established in acidic electrolytes. Sn anode exhibits high deposition efficiency, low polarization, and excellent stability in acidic electrolytes. With the help of H+and a complexing agent, a reversible conversion between Mn2+and Mn3+ions takes place on the graphite surface. Pyrophosphate ligand is initially employed to form a protective layer through a complexation process with Sn4+on the electrode surface, effectively preventing Mn3+from disproportionation and hindering the uncontrollable diffusion of Mn3+to electrolytes. Benefiting from the rational design, the full battery delivers satisfied electrochemical performance including a large capacity (0.45 mAh cm–2at 5 mA cm–2), high discharge plateau voltage (>1.6 V), excellent rate capability (58% retention from 5 to 30 mA cm–2), and superior cycling stability (no decay after 30 000 cycles). The battery design strategy realizes a robustly stable Mn3+/Mn2+redox reaction, which broadens research into ultrafast acidic battery systems.

The ability to create a synergistic effect of nanostructure engineering and its hybridization with conductive carbonaceous material is highly desirable for attaining high-performance lithium ion batteries (LIBs). Herein, we judiciously crafted ZnFe2O4/carbon nanocomposites composed of ZnFe2O4nanoparticles with an average size of 16 ± 5 nm encapsulated within the continuous carbon network as anode materials for LIBs. Such intriguing nanocomposites were yielded in situ viathe pyrolysis-induced carbonization of polystyrene@poly(acrylic acid) (PS@PAA) core@shell nanospheres in conjunction with the formation of ZnFe2O4nanoparticles through the thermal decomposition of ZnFe2O4precursors incorporated within the PS@PAA nanospheres. By systematically varying the ZnFe2O4content in the ZnFe2O4/carbon nanocomposites, the nanocomposite containing 79.3 wt % ZnFe2O4was found to exhibit an excellent rate performance with high capacities of 1238, 1198, 1136, 1052, 926, and 521 mAh g–1at specific currents of 100, 200, 500, 1000, 2000, and 5000 mA g–1, respectively. Moreover, cycling performance of the ZnFe2O4/carbon nanocomposite with 79.3 wt % ZnFe2O4at specific currents of 200 mA g–1delivered an outstanding prolonged cycling stability for several hundred cycles.