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

The large desolvation energy barrier of [Zn(H 2 O) 6 ] 2+ in aqueous zinc ion batteries (AZIBs) results in the undesirable [Zn(H 2 O) 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-C 3 N 4 QDs) as an electrolyte additive for AZIBs. Experimental and theoretical calculations revealed that the doped B atoms could modulate the electron structure of the C 3 N 4 QDs, thus B-C 3 N 4 QDs played an enhanced catalytic role in efficiently decreasing the [Zn(H 2 O) 6 ] 2+ desolvation energy barrier to accelerate its desolvation kinetics in AZIBs, which led to releasing more free Zn 2+ , thereby suppressing side reactions and achieving highly reversible zinc plating/stripping to avoid the formation of zinc dendrites. Benefiting from these merits of B-C 3 N 4 QDs, the corresponding asymmetric Zn||Cu cell realized a high average Coulombic efficiency of 99.29 %. More importantly, the Zn||V 2 O 5 full cell with B-C 3 N 4 QDs 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-C 3 N 4 QDs 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.