Experimental and Theoretical Indagation of Binder-Free N-Graphene Coupling Vanadium Tetrasulfide Aerogel Cathode for Promoting Aqueous Zn-Ion Storage

Aqueous Zn-ion batteries (AZIBs) have acquired great attention owing to their nontoxicity, high safety, and sustainable Zn resources. Nevertheless, the deficiency of applicable electrode materials hampers the advancement of the electrochemical performance for AZIBs. Herein, a N-graphene coupling vanadium tetrasulfide aerogel (VS4@NGA) forming a sponge-like heterostructured architecture is constructed through a hydro thermal and a following freeze-dehydration approach. The unique composite is evaluated as a binder-free electrode for AZIBs and presents competitive zinc storage performance (two times improvement in specific capacity over pristine VS4). The calculations based on density functional theory and electrochemical experimental studies demonstrate that the interconnected porous architecture, meliorated electrical conductivity, decreased adsorption energy, and Zn2+ diffusion energy barrier driven by the combination of VS4 with NGA synergistically realize the enhanced energy storage dynamics and exceptional electrochemical properties of the composite. The reversible Zn ion insertion/extraction reaction mechanism of the composite is clarified by a sequence of ex-situ elemental and structural characterizations. Moreover, the soft-packaged batteries assembled using the composite aerogel suggest the practical application ability of the material in electronic devices. This research offers a simple avenue for constructing a binder-free aerogel-based cathode, which provides a progressive paradigm for the advancement of AZIBs.