2. Academic Validation
  3. Unveiling the Failure Mechanism of Zn Anodes in Zinc Trifluorosulfonate Electrolyte: The Role of Micelle-like Structures

Unveiling the Failure Mechanism of Zn Anodes in Zinc Trifluorosulfonate Electrolyte: The Role of Micelle-like Structures

  • J Am Chem Soc. 2024 Jul 24;146(29):20508-20517. doi: 10.1021/jacs.4c07015.
Xin Shi 1,  Jianning Zeng 1 2,  Ang Yi 1,  Fuxin Wang 3,  Xiaoqing Liu 2,  Xihong Lu 1
Affiliations

Affiliations

  • 1 MOE of the Key Laboratory of Bioinorganic and Synthetic Chemistry, the Key Lab of Low-carbon Chem & Energy Conservation of Guangdong Province, School of Chemistry, Sun Yat-Sen University, Guangzhou 510275, PR China.
  • 2 School of Chemical Engineering and Light Industry, Guangdong Provincial Key Laboratory of Plant Resources Biorefinery, Guangdong University of Technology, Guangzhou 510006, PR China.
  • 3 School of Applied Physics and Materials, Wuyi University, Jiangmen 529020, PR China.
PMID: 38996190 DOI: 10.1021/jacs.4c07015
Abstract

Zinc trifluorosulfonate [Zn(OTf)2] is considered as the most suitable zinc salt for aqueous Zn-ion batteries (AZIBs) but cannot support the long-term cycling of the Zn anode. Here, we reveal the micelle-like structure of the Zn(OTf)2 electrolyte and reunderstand the failing mechanism of the Zn anode. Since the solvated Zn2+ possesses a positive charge, it can spontaneously attract OTf- with the hydrophilic group of -SO3 and the hydrophobic group of -CF3 via electrostatic interaction and form a "micelle-like" structure, which is responsible for the poor desolvation kinetics and dendrite growth. To address these issues, an antimicelle-like structure is designed by using ethylene glycol monomethyl ether (EGME) as a cosolvent for highly reversible AZIBs. The modified electrolyte shows lower dissociation ability to Zn(OTf)2 and higher coordination tendency with Zn2+ compared to the Zn(OTf)2 electrolyte, resulting in the unique solvation structure of Zn2+(H2O)1.2(OTf-)2(EGME)2.8, which significantly reduces the charge of micelle, damages the micelle-like structure, and boosts the desolvation kinetics. Moreover, the reduction of EGME and OTf- can form a robust dual-layered SEI with high Zn2+ ion conductivity. Consequently, the Zn/Cu asymmetric coin cell using ZT-EGME can work at a high rate and a capacity of 50 mA cm-2 and 5 mA h cm-2 for more than 120 cycles, while its counterparts using ZT can barely work. Moreover, a 505.1 mA h pouch cell with practical parameters including a lean electrolyte supply of 15 mL A h-1 and an N/P ratio of ∼3.5 can work for 50 cycles.

Figures
Products