Boron-doped g-C3N4 quantum dots with efficient electrocatalysis for accelerating desolvation to achieve high-performance aqueous zinc-ion batteries

Abstract

The large desolvation energy barrier of [Zn(H₂O)₆]²⁺ in aqueous zinc ion batteries (AZIBs) results in the undesirable [Zn(H₂O)₆]²⁺ formation, which leads to the uncontrollable water-induced side reactions and the intricately dendrites growth, thereby severely hindering the practical applications of AZIBs. Herein, we proposed boron-doped graphitic carbon nitride quantum dots (B-C₃N₄QDs) as an electrolyte additive for AZIBs. Experimental and theoretical calculations revealed that the doped B atoms could modulate the electron structure of the C₃N₄QDs, thus B-C₃N₄QDs played an enhanced catalytic role in efficiently decreasing the [Zn(H₂O)₆]²⁺ desolvation energy barrier to accelerate its desolvation kinetics in AZIBs, which led to releasing more free Zn²⁺, thereby suppressing side reactions and achieving highly reversible zinc plating/stripping to avoid the formation of zinc dendrites. Benefiting from these merits of B-C₃N₄QDs, the corresponding asymmetric Zn||Cu cell realized a high average Coulombic efficiency of 99.29 %. More importantly, the Zn||V₂O₅ full cell with B-C₃N₄QDs still maintained a high specific capacity of ∼149.88 mAh g⁻¹ at 5 A g⁻¹ after 500 charging/discharging cycles, which was much higher than the battery without B-C₃N₄QDs at the same current density. This innovative design conception would inject new vitality to innovation of the low-cost, dendrite-free, and high-performance AZIBs and beyond.