Developing high‐capacity conversional cathode materials for aqueous Zn batteries is promising to improve their energy densities but challenging as well. In this work, three kinds of selenium–sulfur solid solutions and their composites (denoted as SeS14 @ 3D‐NPCF, SeS5.76 @ 3D‐NPCF, and SeS2.46 @ 3D‐NPCF) are proposed and systematically investigated. Due to the introduction of Se and its synergistic effect with S, their physical and electrochemical properties are manipulated; in particular, by optimizing the Se content in these composites, SeS5.76 @ 3D‐NPCF shows a capacity of 1222 mAh g−1 and flat plateau of 0.71 V at 0.2 A g−1, reaching an ultrahigh energy density of 867.6 Wh kg−1 (based on SeS5.76), superior rate capacity of 713 mAh g−1 at 5 A g−1, and stable cycling of 75% capacity retention after 500 cycles. In addition, the Zn storage kinetics is determined by the discharge process, during which SeS5.76 @ 3D‐NPCF is converted into ZnSe and ZnS. More importantly, theoretical calculations reveal that Se can tailor the electron density difference, band structure, and reaction energy of S, which increase its conductivity and reactivity to facilitate the electrochemical reaction with Zn. This work explores high performance conversional cathode materials for aqueous Zn metal batteries and presents an effective strategy to modify their intrinsic properties.

The utilization of Zn anodes to build aqueous Zn–metal batteries has captured extensive attention in the domain of energy storage, but this task faces scientific challenges, such as Zn dendrites and unsatisfactory stripping/plating efficiency as well as gas evolution. Herein, cation‐deficient Cu2–xTe (Cu1.81Te) is proposed as an attractive intercalated anode material for aqueous Zn‐ion batteries. It delivers an ultraflat discharge plateau of 0.2 V (vs Zn2+/Zn) and a capacity of 158 mAh g−1, of which 86% capacity is contributed from the discharge plateau at 0.2 V. Moreover, it shows superior cyclability with 100% capacity retention over 2000 cycles at 2.5 C (1 C = 242 mA g−1). Experimental characterization reveals that it undergoes sequential insertion and conversion mechanism: Zn2+ is first inserted into the Cu2‐xTe which is further converted into Cu and ZnTe. Theoretical calculations demonstrate that the crystal defects in Cu2–xTe can manipulate the electronic structure to enhance reactivity and simultaneously reduce diffusion barriers. Moreover, an aqueous “rocking‐chair” Cu2–xTe//Na3V2(PO4)3 Zn‐ion full battery is demonstrated. It delivers an energy density of 58 Wh kg−1 with a voltage output of 0.98 V, and keeps 92% capacity retention after 1000 cycles. This research provides an ultralow discharge plateau and stable anode material for aqueous Zn‐ion batteries.

Zn metal is a promising anode material for high‐energy‐density aqueous batteries, but it is plagued by dendrite, low stripping/plating efficiency, and inevitable depletion of active Zn. Herein, a low‐intercalation‐potential material, Cu7Te4, is reported as both an anode material and Zn dendrite inhibitor for aqueous Zn batteries. A low plateau of 0.2 V (vs Zn2+/Zn), high capacity of 216 mA h g–1, and superior cyclability over 4200 cycles can be realized by Cu7Te4 anode. Moreover, when Zn is modified with Cu7Te4 layer, a hybrid anode based on “intercalation–deposition” mechanism can be ingeniously developed, in which Zn2+ ions are sequentially inserted into Cu7Te4 and uniformly deposed on Zn at successive low potential. A battery built on such a mechanism sustains more than 1000 h and 1000 times in comparison to less than 100 h and 350 times of a bare Zn. Furthermore, an aqueous “rocking–chair” Cu7Te4//ZnI2 Zn‐ion full battery is further demonstrated, which can realize energy densities of 65.3 Wh kg–1 and 86% capacity retentions after 10 000 cycles. This research contributes to a stable anode material for aqueous Zn batteries and provides an effective strategy to address the Zn dendrite.

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