Achieving stable Pb metal plating/stripping in deep eutectic electrolyte for developing Pb-based hybrid-ion and dual-ion batteries

The growing demand for safe, low-cost, and scalable energy storage systems has prompted the development of battery chemistries beyond conventional lithium-ion and lead–acid technologies. In this work, we propose a novel dual-salt deep eutectic electrolyte, composed of aluminum perchlorate, lead perchlorate, succinonitrile (SN), and acetonitrile (AN), which enables a stable and reversible Pb plating/stripping. The electrolyte exhibits outstanding electrochemical performance, including over 4000 hours of stable cycling in Pb//Pb symmetric cells and 99.96% coulombic efficiency over 2500 cycles in Pb//Pt asymmetric cells. In half-cell configurations, Pb//Na3V2(PO4)3 delivers 65 mAh/g with 98.2% average efficiency after 600 cycles, while Pb//natural graphite (NG) achieves a discharge voltage of 1.7 V and over 100 cycles of stable operation. Spectroscopic analysis (FTIR and Raman) confirm the coordination of Pb²⁺ with SN and AN to form ionic clusters, which effectively suppress free water activity enhancing the overall electrochemical stability of the electrolyte system. Electrochemical measurements (CV and EIS) confirmed that the dual-salt deep eutectic electrolyte contributes to a more stable solvation environment, reduces the desolvation energy of the working ions, thereby increasing the operating voltage and improving overall electrochemical performance. XRD and XPS further confirmed the reversible intercalation of ions in the NVP, as well as the co-deposition of Al3+ on the Pb anode, highlighting the synergistic effect of dual-ion interactions in promoting electrochemical reversibility. Overall, the dual-salt deep eutectic electrolyte enables high-performance Pb-ion based batteries by offering excellent electrochemical stability and enhanced energy output, underscoring its potential for future energy storage applications.