讲座题目：Aqueous battery for large-scale energy storage: towards both high energy density and superior safety

讲座时间：2021年11月30日（周二）晚19：30～20：30

讲座地点：腾讯会议ID：690-107-150 会议密码：123456 （线上）

主讲嘉宾：Prof Chunyi Zhi，City University of Hong Kong

讲座人简介： Chunyi ZHI obtained B.S. degree in Physics at Shandong University and Ph.D. degree in condensed matter physics at Institute of Physics, Chinese Academy of Sciences. After two years’ postdoc at National Institute for Materials Science (NIMS) in Japan, he was promoted to be ICYS researcher, researcher (faculty) and senior researcher (permanent position) in NIMS. Dr. Zhi is now an professor at MSE, CityU.

Dr. Zhi has extensive experiences in flexible energy storage, aqueous electrolyte batteries, zinc ion batteries and highly thermally conducting insulating polymer composites. He has published more than 400 papers, including Nature Review Mater.; Nature Commun.; Energy Environ. Sci.; Adv. Mater.; J. Am. Chem. Soc.; Angew Chem. In. Ed. etc, with an h-index of 101 and other-citation of 36000. He has been granted more than 80 patents.

Dr. Zhi is a recipient of the outstand research award and President Award of CityU, NML Researcher award, IAAM medal and Beijing Science and Technology Award (first class). He is Clarivate Analytics Global highly cited researcher (2019-2021, Materials Science), RSC fellow and member of The Hong Kong Young Academy of Sciences.

Abstract：

Development of energy storage system in the past year focus on improvement of energy density. While the progress is remarkable, safety problems of lithium ion batteries (LIB) have been intensively exposed. On one hand, LIB is not intrinsically safe with very active anode, flammable electrolyte and oxygen-releasing cathode; on the other hand, many application scenarios actually don’t require very high energy density.

We work on aqueous electrolyte batteries to achieve both high energy density and superior safety performance. we show how to activate the desired reversible I0/I+ redox at a potential of 0.99 V vs. SHE by electrolyte tailoring via F-, Cl- ions-containing salts. The electronegative F- and Cl- ions can stabilize the I+ during charging. In an aqueous Zn ion battery based on an optimized ZnCl2 + KCl electrolyte with abundant Cl-, I-terminated halogenated Ti3C2I2 MXene cathode delivers two well-defined discharge plateaus at 1.65 V and 1.30 V, superior to all reported aqueous I2-metal (Zn, Fe, Cu) counterparts. Together with the 108% capacity enhancement, the high voltage output results in a significant 231% energy density enhancement.

In addition, we also develop various approaches to stabilize the Zn anode. We accurately quantifying the hydrogen evolution in Zn metal battery by in-situ battery-gas chromatography-mass analysis. Then, we propose an vapor-solid method for an highly electronically insulating (0.11 mS×cm-1) but high Zn2+ ion conductive (80.2 mS×cm-1) ZnF2 solid ion conductor with high Zn2+ transfer number (0.65) to isolate Zn metal from liquid electrolyte, which can not only prohibit over 99.2 % parasitic hydrogen evolution reaction during cycling but also guide uniform Zn electrodeposition. Meanwhile, Zn@ZnF2//Zn@ZnF2 symmetric cell exhibits excellent stability over 2500 h (over 6250 cycles) with 1 mAh×cm-2 of Zn reversibly cycled at 5 mA×cm-2, and stable cycling under ultrahigh current density and areal capacity (10 mA×cm-2, 10 mAh×cm-2) over 590 h (285 cycles), which far outperforms all reported Zn metal anode in aqueous system. In light of the superior Zn@ZnF2 anode, the practical-level aqueous Zn@ZnF2//MnO2 batteries (~3.2 mAh×cm-2) shows remarkable cycling stability over 1000 cycles with 93.63 % capacity retained at ~100 % coulombic efficiency.