Low‐cost and Non‐flammable Eutectic Electrolytes for Advanced Zn‐I2 Batteries

• Published in: Angewandte Chemie International Edition Vol. 62; no. 39; pp. e202310284 - n/a
• Main Authors: Hao, Junnan, Yuan, Libei, Zhu, Yilong, Bai, Xiaowan, Ye, Chao, Jiao, Yan, Qiao, Shi‐Zhang
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 25.09.2023
• Edition: International ed. in English
• Subjects: Batteries; Electrolytes; Electrolytic cells; Eutectic Electrolyte; Eutectics; Flammability; Low Temperature; Non-Flammable; Polyhydric alcohols; Propylene; Propylene glycol; Shuttle Free; Side reactions; Solvation; Zinc; Zinc chloride; Zinc sulfate; Zn-I2 Battery; Eutectic electrolyte; Zn-I2 battery; non-flammable; low temperature; shuttle free
• ISSN: 1433-7851; 1521-3773; 1521-3773
• DOI: 10.1002/anie.202310284

As a burgeoning electrolyte system, eutectic electrolytes based on ZnCl2/Zn(CF3SO3)2/Zn(TFSI)2 have been widely proposed in advanced Zn‐I2 batteries; however, safety and cost concerns significantly limit their applications. Here, we report new‐type ZnSO4‐based eutectic electrolytes that are both safe and cost‐effective. Their universality is evident in various solvents of polyhydric alcohols, in which multiple −OH groups not only involve in Zn2+ solvation but also interact with water, resulting in the high stability of electrolytes. Taking propylene glycol‐based hydrated eutectic electrolyte as an example, it features significant advantages in non‐flammability and low price that is <1/200 cost of Zn(CF3SO3)2/Zn(TFSI)2‐based eutectic electrolytes. Moreover, its effectiveness in confining the shuttle effects of I2 cathode and side reactions of Zn anodes is evidenced, resulting in Zn‐I2 cells with high reversibility at 1 C and 91.4 % capacity remaining under 20 C. After scaling up to the pouch cell with a record mass loading of 33.3 mg cm−2, super‐high‐capacity retention of 96.7 % is achieved after 500 cycles, which exceeds other aqueous counterparts. This work significantly broadens the eutectic electrolyte family for advanced Zn battery design. Low‐cost and non‐flammable eutectic electrolytes are reported, which not only cost less than 1/200 of Zn(CF3SO3)2/Zn(TFSI)2‐based eutectic electrolytes, but also show evident universality in various polyhydric alcohol solvents. Moreover, these eutectic electrolytes greatly expand the range of eutectic electrolytes available for advanced battery design.