Boron-Doped G-C 3 N 4 Quantum Dots with Efficient Electrocatalysis for Accelerating Desolvation to Achieve High-Performance Aqueous Zinc-Ion Batteries

We would like to submit our manuscript entitled "Boron-doped g-C3N4 Quantum Dots with Efficient Electrocatalysis for Accelerating Desolvation to achieve High-Performance Aqueous Zinc-ion Batteries" for publication in Journal of Energy Storage .Lithium-ion batteries (LIBs) dominate the main rechargeable electrochemical energy storage devices, whereas their disadvantages including scarce resources, flammable characteristics and environmental pollution motivate us to develop novel safe and sustainable electric storage energy devices. Rechargeable aqueous Zn-ion batteries (AZIBs) have become the state-of-the-art candidates of LIBs, since Zn metal has the merits of rich abundance, high security and environmentally benign. However, the reaction of Zn2+ ions with active water molecules [Zn(H2O)6]2+ form the solvated sheath structures, which results in inevitable zinc corrosion, serious hydrogen evolution reaction (HER), and rampant zinc dendrite growth, thereby severely compromising the commercial development and practical utilization of AZIBs.In order to address the above issues, we herein reported the preparation of B-doped g-C3N4 quantum dots (B-C3N4QDs) via a calcination combined hydrothermal process by using urea and boric acid as raw materials. The obtained B-C3N4QDs was used as an additive in a ZnSO4 (ZSO) solution and the B-C3N4QDs@ZSO electrolyte was obtained. B-C3N4QDs was able to reduce the desolvation energy barrier of [Zn(H2O)6]2+, thus efficiently homogenizing the Zn2+ flux. Accordingly, the fabricated Zn||V2O5 full cell using B-C3N4QDs@ZSO delivered a high specific capacity of ~149.88 mAh g-1 and meanwhile realized an impressive coulombic efficiency (CE) of 100% over 2000 cycles at 5 A g-1, highlighting the potential of AZIBs. Molecular dynamics (MD) simulation and DFT calculations results revealed that the B could regulate and control the electron structure, which was able to efficiently decrease the [Zn(H2O)6]2+ desolvation energy barrier favorable for releasing more free Zn2+. This work not only proposes a novel understanding of Zn deposition by efficiently promoting the desolvation but also provides the new protocol for developing dendrite-free aqueous AZIBs.