Rechargeable aqueousZn-Mn batteries have garnered extensive attention for next-generation high-safety energy storage. However, the charge-storage chemistry of Zn-Mn batteries remains controversial. Prevailing mechanisms include conversion reaction and cation (de)intercalation in mild acid or neutral electrolytes, and a MnO 2 /Mn 2+ dissolution−deposition reaction in strong acidic electrolytes. Herein, a Zn 4 SO 4 •(OH) 6 •xH 2 O (ZSH)-assisted deposition−dissolution model is proposed to elucidate the reaction mechanism and capacity origin in Zn-Mn batteries based on mild acidic sulfate electrolytes. In this new model, the reversible capacity originates from a reversible conversion reaction between ZSH and Zn x MnO(OH) 2 nanosheets in which the MnO 2 initiates the formation of ZSH but contributes negligibly to the apparent capacity. The role of ZSH in this new model is confirmed by a series of operando characterizations and by constructing Zn batteries using other cathode materials (including ZSH, ZnO, MgO, and CaO). This research may refresh the understanding of the most promising Zn-Mn batteries and guide the design of high-capacity aqueous Zn batteries.
Flexible aqueous rechargeable batteries that integrate excellent mechanical flexibility and reliable safety hold a great promise for next‐generation wearable electronics. Unfortunately, currently available options are unsatisfactory due to their low specific capacity, limited energy density, and unstable voltage output. Herein, to overcome these challenges, high theoretical specific capacity zinc and sulfur as the anode and cathode are selected, respectively. Furthermore, a strategy is proposed, that decoupling charge carriers in anolyte and catholyte to simultaneously endow the zinc anode and sulfur cathode with optimal redox chemistry, maximizes the energy storage of flexible aqueous batteries. The new zinc–sulfur hybrid battery possesses merits of ultrahigh theoretical specific capacity (3350 mAh gS−1) and volumetric energy density (3868 Wh L−1), low cost, ecofriendliness, and ease of fabrication and is a promising next‐generation aqueous energy storage system. The fabricated flexible aqueous zinc–sulfur hybrid battery delivers a stable output voltage (release 92% of its full capacity within a small voltage drop of 0.15 V) and an ultrahigh reversible capacity of 2063 mAh gS−1 at 100 mA gS−1, thus setting a new benchmark for flexible aqueous batteries and is promising to play a part in future flexible electronics.
A network-like MG-Co composite with adsorption and catalysis for Na2Sx is synthesized as a S host for room temperature Na–S batteries, exhibiting excellent electrochemical performance.
Pompon-like NiCo2Se4 can effectively promote the penetration of an electrolyte, increase electron and ion diffusion channels, alleviate volume expansion and achieve excellent sodium storage performance.
Prussian blue and its analogues with three-dimensional frame structures have been shown to be of great importance in the research and development of sodium-ion batteries (SIBs). Herein, we develop a simple and convenient self-template method to prepare a hollow-structured Prussian blue analogue (CoFe-PBA). This structure is conducive to buffer the volume changes during ion extraction and insertion processes and shorten the ion diffusion path. When further building a thin polydopamine (PDA) coating, the synthesized CoFe-PBA@PDA exhibits a high discharge capacity of 123.1 mAh g −1 at 0.1 A g −1 with a capacity retention of 71.5% after 500 cycles. Moreover, the capacity retention of CoFe-PBA@PDA after 100 cycles is 14.3% higher than that of the two comparison samples. In addition, the reversible structure of CoFe-PBA@PDA without forming a new phase was verified by in situ X-ray diffraction. This work may provide another design idea or strategy for improving the stability of the PBA cathodes used in SIBs.
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