In-situ constructed solvated carbon quantum dot clusters to achieve uniform Zn plating in aqueous zinc ion batteries

Abstract

Zinc ion batteries (ZIBs) have become the most competitive candidates for the next-generation energy storage systems due to its low-price, good safety and high theoretical capacity. However, the uncontrollable dendrite growth and parasitic side reactions still hinder the practical application of the zinc ion batteries. Herein, a hybrid functionalized carbon quantum dots (FCQDs)/ZnSO4 electrolyte is in-situ synthesized via a simple one-pot hydrothermal method with glucose as precursor. The created FCQDs possess abundant anionic groups like hydroxyl, carboxyl and sulfonic acid groups, and those anionic groups can strongly absorb Zn2+ ions and then the FCQDs, Zn2+ and water molecules together generate a special solvation structure of solvated carbon quantum dot clusters [FCQDsZnx(H2O)y]2x+. The solvated FCQDs clusters can help to in-situ induce the uniform Zn deposition through a co-plating of Zn atoms and the functionalized FCQDs. Additionally, this unique solvation structure promotes easier dissociation of solvation water molecules, thus decreasing the de-solvation energy. The lower de-solvation energy barrier can help to restrain the water decomposition and the related by-products. Benefiting from the construction of this unique solvated FCQDs clusters, the hybrid electrolyte with FCQDs endows a better performance of both Zn||Zn symmetric cells and full ZIBs.