Succinonitrile Electrolyte Additive for Stabilizing Aqueous Zinc Metal Batteries.

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Aqueous zinc-ion batteries (ZIBs) offer safer, cheaper, and greener alternatives to lithium-ion batteries.
• Conventional zinc sulfate electrolytes in ZIBs face limitations in cycle life and zinc dendrite formation.
• Advanced electrolyte design is essential for high-performance ZIBs.

Purpose of the Study:

• To develop a novel electrolyte system for ZIBs to overcome limitations of conventional electrolytes.
• To improve the cycling stability and suppress dendrite growth in ZIBs.
• To engineer an electrolyte that promotes uniform zinc deposition and stable solid-electrolyte interphase (SEI) formation.

Main Methods:

• Aqueous Zn(OTf)2 solutions were engineered with succinonitrile (SN) to form network electrolytes.
• The effect of SN on the hydrogen bonding network and water molecule reactivity was investigated.
• The composition of the formed SEI layer was analyzed, focusing on Zn3N2/ZnF2 formation.
• Symmetric and full ZIB cells were assembled and tested for cycling performance and capacity retention.

Main Results:

• The succinonitrile network electrolyte disrupted hydrogen bonding and mitigated side reactions.
• SN additives reduced water reactivity, promoting smooth zinc deposition and a stable Zn3N2/ZnF2 SEI.
• Symmetric cells demonstrated exceptional cycling stability, lasting 877 hours.
• Full batteries retained an impressive capacity of 151.2 mAh g-1 after 2000 cycles at 5 A g-1.

Conclusions:

• The engineered succinonitrile network electrolyte is a promising strategy for high-performance aqueous zinc-ion batteries.
• This approach effectively enhances cycle life and suppresses zinc dendrites by controlling the electrolyte structure and SEI formation.
• The findings pave the way for developing advanced electrolytes for next-generation zinc-metal batteries.