Solvation Chemistry Modulation by Dual-Aprotic Polar Additives in Aqueous Zinc-Ion Batteries

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Aqueous zinc-ion batteries (AZIBs) face challenges like zinc dendrite growth and hydrogen evolution reactions (HER) that limit commercialization.
• Controlling the zinc ion (Zn²⁺) solvation structure is crucial for mitigating these issues and improving battery performance.
• Existing strategies often struggle to simultaneously address dendrite formation and parasitic reactions.

Purpose of the Study:

• To develop a novel dual-electrolyte modification strategy for enhancing the stability and performance of AZIBs.
• To investigate the effect of dual aprotic polar solvents on Zn²⁺ desolvation and interfacial deposition kinetics.
• To enable a highly reversible and stable zinc anode through optimized electrolyte engineering.

Main Methods:

• Employed a dual-electrolyte modification strategy using two aprotic polar solvents at an optimized ratio.
• Incorporated dual-aprotic polar additives (DHZS) into the electrolyte to tailor the Zn²⁺ solvation structure and interphase chemistry.
• Conducted electrochemical analyses, including cycling tests of Zn||Zn symmetric cells, Zn||Cu asymmetrical cells, and Zn||V₂O₅ full cells.

Main Results:

• The DHZS additives effectively regulated Zn²⁺ solvation structure, controlled crystallographic deposition orientation, and modulated the Zn-electrolyte interphase.
• Achieved uniform zinc deposition and significantly extended the operational lifespan of AZIBs, with Zn||Zn symmetric cells exceeding 690 h at 5 mA cm^-2.
• Demonstrated excellent reversibility in asymmetrical Zn||Cu cells (average Coulombic efficiency >99% over 250 cycles) and good capacity retention in full cells (∼70% over 1000 cycles).

Conclusions:

• The cooperative effect of dual electrolyte additives provides an effective strategy for uniform zinc deposition and suppression of corrosion.
• Enhanced Zn²⁺ transport and interfacial stability were achieved, leading to high-durability AZIBs.
• This electrolyte engineering approach offers a promising pathway for the commercialization of high-performance aqueous zinc-ion batteries.