Dual-Doped Graphene Quantum Dots to Promote Long-Life Aqueous Zn-ion Batteries

Abstract

As the next generation of advanced energy storage devices, aqueous Zn ions batteries (AZIBs) still face many challenges, especially dendrites on the Zn metal anode and side reactions. Although an interface modification strategy has been applied to optimize the stability of Zn metal anodes and has shown some improvement, they are still far from meeting the requirements for practical applications. There is a lack of consideration for designing a multifunctional solid electrolyte interphase (SEI) which modifies the solvation/desolvation structure of Zn ion at the interface of Zn metal anodes. Herein, we constructed an amphiphilic SEI with hydrophilic and hydrophobic properties: N, S dual-doped graphene quantum dots (GQDs). The N, S dual-doped GQDs have been synthesized using a one-step hydrothermal approach and were utilized for Zn anode surface modification. When regulating the solvation structure of the Zn ion interface by N, S dual-doped GQDs, it also promotes its desolvation kinetics, optimizes the interfacial behavior of Zn ion deposition to prohibit Zn dendrite growth, and suppresses side reactions in the Zn anode surface. The Zn|Zn symmetric cell has achieved a long cycle life of more than 800 h at 5 mA cm⁻². The Zn|V₂O₅ battery has achieved an excellent performance of more than 80% capacity retention after 1400 cycles at 1 A g⁻¹. This provides another novel and cost-effective path for the SEI design of aqueous Zn-ion batteries.