Recently, Professor Yong Zhao’s research group from Henan University has made a new progress in the field of lithium metal batteries. The relevant results entitled "Cationic Size Effect Promoting Dissolution of Nitrate Anion in Ester Electrolyte for Lithium–Metal Batteries" were published in ACS Energy Letters. ACS Energy Letters currently ranks the #1 journal in the Web of Science Electrochemistry category, and the top 10 journals for Physical Chemistry, Energy & Fuels, and Nanoscience & Nanotechnology.
The construction of stable solid-electrolyte-interface (SEI) with high ionic conductivity at the interface between Li anode and ester electrolyte is challenging, while it is critical to obtain the long-term stability Li metal batteries when coupling with high voltage cathode materials. Herein, a “cationic size effect” is firstly demonstrated to promote the dissolution of NO3- anion in ester electrolyte, and a SEI layer on Li anode containing Li3N with high ionic conductivity is constructed, showing the high Coulombic efficiency and long cycle stability. By adjusting the size of quaternary ammonium (R4N+) cation, the charge localization state of cation and the binding energy between R4N+ and NO3- are regulated, achieving the high solubility (1.8 M) of tetraethyl ammonium nitrate (TEAN) in ethylene carbonate. Using TEAN as an ester electrolyte additive, the Li/Li symmetric, Li/Cu，Li/LiFePO4 and Li/NCM811 batteries can achieve considerably prolonged cycle life. The concept for “cationic size effect” mediating the dissolution of anion in the specific solvents can provide an important strategy for various fields including of batteries application. (ACS Energy Letters, DOI: 10.1021/acsenergylett.1c02495)
Scheme 1. The schematic image for dissolution of NO3- anion by cation size effect and formation of SEI layer containing Li3N with high ionic conductivity on Li electrode.
PhD candidate Zhijie Guo and Dr. Xiaosheng Song are the co-first authors of the paper, and Professor Yong Zhao is the corresponding author. This work is supported by the Organization Department of the CPC Central Committee, the National Natural Science Foundation of China, the Science and Technology Department of Henan Province, the Education Department of Henan Province and Henan University.
Article link:https://pubs.acs.org/doi/full/10.1021/acsenergylett.1c02495
