VSe2 is demonstrated as an appealing candidate for Zn storage, which exhibits excellent electrochemical performance, in particular, rate performance.

The aqueous zinc-ion battery (ZIB) is one of several promising energy storage systems because of its low cost, nontoxicity, and high safety. In addition, Zn metal exhibits low redox potential in aqueous solution. However, one big obstacle in the development of ZIBs is the dendrite growth and corrosion reaction of Zn anode. Exploration of the Zn host anode material with high reversible capacity and low redox voltage would be an effective strategy. Herein, layered TiS2 is successfully demonstrated as a durable host material for neutral aqueous ZIBs with a relatively low charge voltage of 0.4 V. The TiS2 material delivers a stabilized capacity of 120 mAh g–1 at 100 mA g–1, high rate capability (76 mAh g–1 at 1000 mA g–1), and good cycle performance (70% capacity retention after 500 cycles at 1000 mA g–1) in a Zn/TiS2 cell. The outstanding electrochemical properties are attributed to the excellent maintenance of TiS2 during cycling in which the Zn2+ cations can be easily inserted/extracted into/from the layered structure with slight structural change, observed from ex situ X-ray diffraction investigation. Mechanism study reveals that TiS2 goes through a reversible (de)­interclation reaction in accompany with valence change of titanium element during cycling. This study would benefit the exploration and design of host materials for rechargeable aqueous batteries, especially for the anode.

Zn metal, with abundant resource and low cost, exhibits large theoretical capacity and relatively negative electrode potential (−0.76 V vs SHE), which endows zinc-ion batteries with promising energy storage systems. Though great efforts have been made recently, challenges remain in the development of Zn-ion batteries, especially for the zinc anode. The zinc dendrite formation and reaction irreversibility during cycling lead to increased polarization and poor cycle performance of the battery. In addition, a Zn plate is usually used as anode when the battery is assembled, which is far beyond the theoretical quantity of Zn requested in the redox reaction, which resulted in low energy density of the battery. Zn and carbon composites are reported in literature as an efficient strategy to address these problems, yet the impact of the preparation of Zn/C composites, the corresponding structure, and the charge/discharge parameters on their electrochemical performance are not revealed. In this contribution, Zn@Carbon paper (CP) was prepared via electrodeposition of Zn on carbon paper and used as anode of the zinc-ion battery. It is found that the morphology and electrochemical performance of Zn@CP are quite dependent on the electrodeposition current density during preparation, which might be related to nucleation activation energy at the beginning of the electrodeposition. Beyond the preparation of Zn@CP, the depth of discharge (DOD) during cycling is crucial in determining its electrochemical behavior. This work would benefit the design of Zn-based composite anode materials for further advancement of Zn-ion batteries with superior performance.

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