Electric Double Layer Oriented Eutectic Additive Design toward Stable Zn Anodes with a High Depth of Discharge

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Aqueous zinc ion batteries face challenges with hydrogen evolution reaction (HER) and dendrite growth, limiting practical applications.
• Current ZnSO4-based electrolytes struggle to meet performance demands due to these issues.

Purpose of the Study:

• To design a novel eutectic additive, glycerophosphorylcholine (GPC), for stabilizing zinc anodes in aqueous electrolytes.
• To investigate the mechanism by which GPC regulates the electric double layer (EDL) structure and suppresses detrimental side reactions.

Main Methods:

• Rational design of a highly polarized eutectic additive (GPC).
• Analysis of GPC's effect on the EDL structure and hydrogen bond network.
• Investigation of GPC's role in forming a protective solid-electrolyte interphase (SEI).
• Electrochemical testing of Zn anodes and Zn||VS2 full cells.

Main Results:

• GPC effectively suppresses HER by regulating the EDL hydrogen bond network.
• GPC promotes the formation of a robust Zn$_{x}$P$_{y}$O$_{z}$-rich SEI, preventing dendrite growth.
• Engineered Zn anodes exhibit reversible cycling for over 1450 hours at a high depth of discharge (45.3%).
• Aqueous Zn||VS2 full cells achieve high capacity (185.7 mAh g$^{-1}$) and 90.4% retention over 220 cycles.

Conclusions:

• EDL-oriented eutectic additive engineering with GPC is a viable strategy for high-performance aqueous batteries.
• This approach significantly enhances the stability and cycle life of zinc anodes.
• The findings offer insights into electrolyte and interface engineering for advanced aqueous energy storage systems.