High performance Zn-I2 battery with acetonitrile electrolyte working at low temperature

Large scale applications of metal-iodine batteries working at sub-zero degree have been challenged by the limited capacity and performance degradation. Herein, we firstly propose a Zn-I-2 battery working at low temperature with a carbon composite material/iodine (CCM-I-2) cathode, a Zn anode and an environmentally tolerable Zn(ClO4)(2)-ACN electrolyte. The CCM framework with hierarchical porous structure endows a powerful iodine-anchoring to overcome undesirable dissolution of iodine in organic electrolyte, and the Zn(ClO4)(2)-ACN electrolyte with low freezing point and high ionic conductivity enhances the low temperature performance. The synergies enable an efficiently reversible conversion of Zn-I-2 battery even at -40 degrees C. Therefore, the resultant Zn-I-2 battery delivers a high specific capacity of 200 mAh.g(-1), which is fairly approximate to the theoretical capacity of l(2) (211 mAh.g(-1)) and a superior cycling stability with minimal capacity fading of 0.00043% per cycle over 7,000 times under 2C at -20 degrees C. Furthermore, even at -40 degrees C, this Zn-I-2 battery still exhibits a good capacity retention of 68.7% compared to the capacity at 25 degrees C and a rapid capacity-recover ability with elevating temperature change. Our results distinctly indicate this Zn-I-2 battery can be competent for the practical application under low temperature operation.

Automated summary

A zinc-iodine battery working at low temperature was proposed, achieving high specific capacity and superior cycling stability through optimized materials and electrolyte. The battery showed potential for practical application under low temperature operation.