Electrolyte Solvation Structure Design for High Voltage Zinc-Based Hybrid Batteries

Zinc (Zn) metal anodes have enticed substantial curiosity for large-scale energy storage owing to inherent safety, high specific and volumetric energy capacities of Zn metal anodes. However, the aqueous electrolyte traditionally employed in Zn batteries suffers severe decomposition due to the narrow voltage stability window. Herein, we introduce N-methylformamide (NMF) as an organic solvent and modulate the solvation structure to obtain a stable organic/aqueous hybrid electrolyte for high-voltage Zn batteries. NMF is not only extremely stable against Zn metal anodes but also reduces the free water molecule availability by creating numerous hydrogen bonds, thereby accommodating high-voltage Zn||LiMn2O4 batteries. The introduction of NMF prevented hydrogen evolution reaction and promoted the creation of an F-rich solid electrolyte interphase, which in turn hampered dendrite growth on Zn anodes. The Zn||LiMn2O4 full cells delivered a high average Coulombic efficiency of 99.7% over 400 cycles.

Automated summary

In this study, N-methylformamide (NMF) was introduced as an organic solvent and its solvation structure was modulated to obtain a stable organic/aqueous hybrid electrolyte for high-voltage Zn batteries. NMF showed excellent stability against Zn metal anodes and reduced the availability of free water molecules by creating numerous hydrogen bonds, allowing for the use of high-voltage Zn||LiMn2O4 batteries. The introduction of NMF prevented hydrogen evolution reaction and promoted the formation of an F-rich solid electrolyte interphase, thereby inhibiting dendrite growth on Zn anodes. The Zn||LiMn2O4 full cells exhibited a high average Coulombic efficiency of 99.7% over 400 cycles.