Dr. Denis Yu’s paper titled “An All-Fluorinated Electrolyte Towards High Voltage and Long Cycle Performance Dual-Ion Batteries” has been published in Advanced Energy Materials (IF: 29.37; DOI:10.1002/aenm.202103360) and featured as inside cover in the Vol. 12, No. 19. 

About the project
Dual-ion battery (DIB) is a promising energy storage system that demonstrates high-power characteristic and fast-charging capability. However, conventional electrolytes are not compatible with the high-voltage graphite cathode and the reactivity Li metal anode, thus leading to poor cycle stability and low Coulombic efficiency of the DIB. Here, Dr. Yu’s team designed an all-fluorinated electrolyte that can enable a highly stable operation of the graphite||Li DIB up to 5.2 V by forming robust and less-resistive passivation films on both electrodes to reduce side reactions. The electrolyte allows reversible PF₆^- anion insertion/extraction and Li⁺ cation plating/stripping in the graphite||Li battery, achieving stable cycling with 94.5% capacity retention over 5000 cycles at 500 mA g^-1, high capacity utilization of 91.8% of the available charge capacity at 50 C (5000 mA g^-1) and also minimal self-discharge. At a low temperature of 0 ℃, this all-fluorinated electrolyte exhibits 97.8% of the room temperature reversible capacity, along with ~ 100% capacity retention after more than 3000 cycles, at 5 C. The newly developed DIB can be charged and discharged within a few minutes. It is promising for new applications such as green transportation and renewables that would require a fast response rate.

Dr. Yu is the sole corresponding author of this paper. The first author is Dr. Yao Wang, a PhD graduate of SEE. The other co-authors include Dr. Yanjun Zhang, Mr. Shuyu Dong, Dr. Pui-Kit Lee, Dr. Zehua Peng, Dr. Wenchong Zhou, and Dr. Patrick Sit from SEE.