Dual-Ion Metal Electrolyte Additives Regulate the Interfacial Reaction of Zinc Anodes

In this work, a low-cost rare-earth metal salt, ammonium cerium(IV) sulfate (ACS), has been selected as a multifunctional electrolyte additive. During cycling, the introduction of tetravalent Ce⁴⁺ ions plays a crucial role. It forms a dynamic shielding layer on the anode's zinc protrusions, improving energy storage performance by regulating and inhibiting issues. This layer effectively guides the homogeneous deposition of Zn²⁺ ions and acts as a safeguard to prevent excessive zinc dendrite formation. Additionally, the incorporation of NH₄⁺ dynamically regulates the electrolyte's pH during cycling, reducing OH^- content and suppressing side reactions and the hydrogen evolution reaction. When utilizing this electrolyte, the Zn//Zn cell has a long cycling life of 2000 h under the conditions of 1 mA cm^-2 and 1 mAh cm^-2. The Zn//Cu asymmetric cell attains a mean CE exceeding 99.7% after 350 cycles under the conditions of 1 mA cm^-2 and 1 mAh cm^-2. More importantly, Zn-ion capacitors assembled with this electrolyte demonstrate extraordinary cycling stability, with over 34,000 cycles under a condition of 1 A g^-1.