Coal-derived carbon quantum dots modified MnO2 nanowires as cathode for enhanced aqueous zinc-ion battery

Manganese-based materials are widely used as cathode materials in aqueous zinc-ion batteries (AZIBs) because of their abundant natural reserves, low production costs, and high theoretical capacity. However, their susceptibility to disproportionation reactions and ease of dissolution, significantly hinder their practical applications. To address these challenges, coal-based carbon quantum dots (CQDs) were first synthesized via a solvothermal process using anthracite powder as the raw material. These CQDs were subsequently combined with manganese dioxide (MnO₂) to create MnO₂@CQDs composites for use as cathode materials in AZIBs. The incorporation of CQDs into MnO₂ introduced additional active sites, effectively enhancing the conductivity and stability of MnO₂. As a result, the synthesized MnO₂@CQDs composites exhibited superior electrochemical zinc storage performance. Specifically, they delivered a specific capacity of 160 mAh g⁻¹ at a current density of 0.1 A g⁻¹, and maintained 95.4 % of their initial capacity after 500 cycles at 1 A g⁻¹. This study provides a new idea for the development of manganese-based cathode materials by integrating value-added earth-abundant coal-derived CQDs as a promoter, offering promise for the advancement of AZIBs technology.