Interface Regulation by Functional Additives Towards Highly Stable Zn Batteries in Aqueous Electrolyte

Aqueous zinc batteries have emerged as highly promising route for large-scale energy storage applications due to their inherent safety, higher energy density, lower raw material costs, simpler manufacturing processes, and non-toxicity. Despite these advantages, challenges such as Zn dendrite formation, hydrogen evolution side reactions, and Zn metal anode corrosion hinder their practical implementation. These challenges are intrinsically linked to Zn deposition behavior, which is influenced by the critical interfaces adjacent to the Zn electrode. To address these problems, here the interface between the Zn electrode and the aqueous electrolyte has been effectively regulated using electrolyte additive strategies to enhance the electrochemical performance of Zn batteries. Succinic acid (SA) was identified as a viable and cost-effective additive that significantly improves the reversibility and cycling stability of aqueous Zn batteries by altering the solvation structure of Zn ions and preferentially adsorbing onto the Zn anode surface. This approach results in Zn anodes in a 2 m ZnSO4 electrolyte containing 0.1 m SA exhibiting remarkable improvements, with Zn||Zn symmetric cells achieving a cycle life of 5500 hours and Zn||Cu cells demonstrating an average Coulombic efficiency of approximately 99.7% over 1300 cycles. Further advancements were made with a novel aqueous electrolyte composed of 1 m ZnSO4 and 0.1 m SS (sodium sulfanilate) additive, where abundant amino groups of SS molecules promoted the uniform Zn deposition and inhibited corrosion, leading to long-term cycling stability of over 1000 hours at 1 mA cm-2 and 1 mAh cm-2 and high Coulombic efficiency (CE) of Zn plating/stripping in Zn||Cu cells. Additionally, a low-cost strategy utilizing a very small amount of pyridine electrolyte additive leveraged results in dendrite-free and homogeneous Zn deposition through a unique electrostatic repulsion mechanism during the Zn plating/stripping process. This enables a remarkable cycling stability in Zn||Zn symmetrical cells for over 2000 hours at 1 mA cm-2 and 1 mAh cm-2, with superior performance even at high current densities and capacities. The full batteries with an Al0.1V2O5·1.5 H2O (AIVO) cathode achieved a lifespan of 800 cycles, significantly surpassing the conventional electrolytes. Therefore, these findings offer a scalable electrolyte additive strategy for developing advanced dendrite-free Zn anodes and high-performance aqueous Zn batteries, paving the way for their potential applications in large-scale energy storage systems.