Nitrogen and Oxygen Co-Doped Graphene Quantum Dots as a Trace Amphipathic Additive for Dendrite-Free Zn Anodes

Abstract

The practical implementation of aqueous zinc-ion batteries (AZIBs) has encountered obstacles stemming from the limited reversibility of the zinc anode, primarily due to dendrite proliferation and water-induced reactions occurring. In this investigation, a novel bifunctional interphase is proposed by integrating nitrogen and oxygen group graphene quantum dot (N-O-GQD) additives into the electrolyte. Experimental results and theoretical calculations demonstrate that the amphipathic N-O-GQD additive enhances the stability of the electrode by forming a protection layer on Zn surface. The zincophilic and hydrophobic nitrogen function groups stick to the surface of Zn electrodes to form a hydrophobic layer that shields water molecules from the electrode and promotes the uniform deposition of Zn. The hydrophilic hydroxyl function groups are exposed to the electrolyte to improve the compatibility at the electrode/electrolyte interface. As a result, the amphipathic N-O-GQD additive enables a robust cycling performance at high depth of discharge (DOD). Significantly, cells incorporating N-O-GQDs demonstrate a remarkable Coulombic efficiency of 99.7% over 900 cycles and sustain dendrite-free cycling for 564 h (DOD = 51%). Particularly noteworthy is the performance of the modified Zn||ZnVO full cell with robust cycling behavior, enduring 4 000 cycles at 10 A g⁻¹.