Ultra-stable Zinc Metal Anodes at-20 °C through Eutectic Solvation Sheath in Chlorine-functionalized Eutectic Electrolytes with 1,3-Dioxolane

The brain-storm of designing low-cost and commercialized eutectic electrolytes for zinc (Zn)-based electrochemical energy storage (ZEES) remains unresolved and attractive, especially when implementing it at low temperatures. Here, we report an appealing layout of advancing chlorine-functionalized eutectic (Cl-FE) electrolytes via exploiting Cl anion-induced eutectic interaction with Zn acetate solutions. This novel eutectic liquid shows high affinity to collaborate with 1,3-dioxolane (DOL) and is prone to constitute Cl-FE/DOL-based electrolytes with a unique inner/outer eutectic solvation sheath for the better regulation of Zn-solvating neighboring and reconstruction of H-bonding. The side reactions are effectively restricted on Zn anodes and a high Coulombic efficiency of 99.5 % can be achieved over 1000 cycles at -20 & DEG;C with Zn//Cu setups. By prototyping scale-up Zn-ion pouch cells using the optimal eutectic liquid of 3ZnOAc(1.2)Cl(1.8)-DOL, we obtain improved electrochemical properties at -20 & DEG;C with a high capacitance of 203.9 F g(-1) at 0.02 A g(-1) in a range of 0.20-1.90 V and long-term cycling ability with 95.3 % capacitance retention at 0.2 A g(-1) over 3,000 cycles. Overall, the proposal of ideal Cl-FE/DOL-based electrolytes guides the design of sub-zero and endurable aqueous ZEES devices and beyond.

Automated summary

The design of low-cost and commercialized eutectic electrolytes for zinc-based electrochemical energy storage (ZEES) is still a challenge especially at low temperatures. This study proposes the use of chlorine-functionalized eutectic (Cl-FE) electrolytes to regulate the solvation of zinc and improve the performance of ZEES devices. The introduction of Cl anion-induced eutectic interaction with Zn acetate solutions allows the formation of Cl-FE/DOL-based electrolytes with a unique solvation sheath, leading to restricted side reactions on zinc anodes and high Coulombic efficiency.