Construction of Artificial Interface Layer in the Fly Ash Suspension for Durable Zn Anode

Zinc ion batteries (ZIBs) are an intriguing option due to their safety, nonflammability, and environmental friendliness. However, the uncontrolled formation of Zn dendrites, which can lead to short circuits, limits their broader application. In this study, we designed an artificial interface layer on the surface of the Zn metal anode using a hydrothermal reaction in a fly ash suspension. This process created a zinc silicate (ZnSiO3) thin film on the Zn surface, which helps control Zn ion accumulation and facilitates their diffusion, thereby enhancing the performance of the Zn anode. As a result, the symmetric cells achieved an impressive long-term lifespan of 1900 h at a current density of 0.5 mA·cm–2, significantly outperforming bare Zn, which only lasted 68 h. Furthermore, the full cells demonstrated cycling stability with a capacity retention of 73% after 1000 cycles at a current density of 5 A·g–1, compared to 53% for bare Zn. This work illustrates the potential of modifying Zn using fly ash, primarily composed of SiO2, to create a ZnSiO3 thin film layer. This strategy realizes the reuse of fly ash on the surface of Zn anode and promotes the further development of ZIBs.