Durable modulation of Zn(002) plane deposition via reproducible zincophilic carbon quantum dots towards low N/P ratio zinc-ion batteries†

Abstract

Aqueous zinc-ion batteries (ZIBs) are promising candidates for next-generation energy storage systems due to their intrinsic safety, environmental friendliness, and low cost. However, the uncontrollable Zn dendrite growth during cycling is still a critical challenge for the long-term operation of ZIBs, especially under harsh lean-Zn conditions. Herein, we report nitrogen and sulfur-codoped carbon quantum dots (N,S-CDs) as zincophilic electrolyte additives to regulate the Zn deposition behaviors. The N,S-CDs with abundant electronegative groups can attract Zn²⁺ ions and co-deposit with Zn²⁺ ions on the anode surface, inducing a parallel orientation of the (002) crystal plane. The deposition of Zn preferentially along the (002) crystal direction fundamentally avoids the formation of Zn dendrites. Moreover, the co-depositing/stripping feature of N,S-CDs under an electric field force ensures the reproducible and long-lasting modulation of the Zn anode stability. Benefiting from these two unique modulation mechanisms, stable cyclability of the thin Zn anodes (10 and 20 μm) at a high depth of discharge (DOD) of 67% and high Zn||Na₂V₆O₁₆·3H₂O (NVO, 11.52 mg cm⁻²) full-cell energy density (144.98 W h Kg⁻¹) at a record-low negative/positive (N/P) capacity ratio of 1.05 are achieved using the N,S-CDs as an additive in ZnSO₄ electrolyte. Our findings not only offer a feasible solution for developing actual high-energy density ZIBs but also provide in-depth insights into the working mechanism of CDs in regulating Zn deposition behaviors.