Developing High-Voltage Electrolytes Via Anode-Free Cell Configuration

Abstract

Currently, concentrated electrolyte solutions are attracting special attention because of their unique characteristics such as unusually improved oxidative stability on both the cathode and anode sides, the absence of free solvent, the presence of more anion content, and the improved availability of Li+ ions. The solvation structure of concentrated electrolytes is different from that of diluted electrolyte and the formation of ion-pairs takes place in concentrated electrolytes, which helps form a good solid-electrolyte-interphase. However, the ionic conductivity of concentrated electrolytes is normally lower compared to that diluted electrolytes. Most of the concentrated electrolytes reported are lithium bis(fluorosulfonyl)imide (LiFSI) salt with ether-based solvents because of the high solubility of salts in ether-based solvents. Here, an anode-free cell (Cu//LiNi1/3Mn1/3Co1/3O2) with all irreversible features is employed as a tool to develop non-flammable LiPF6-based high-voltage electrolyte. Two extreme electrolytes are chosen for comparison and understanding the fundamental science behind[1,2]. The best electrolyte developed also shows much better cycling performance in high-voltage lithium-metal batteries (HVLMBs) and high-voltage lithium-ion batteries (HVLIBs) compared to the commercial electrolyte, indicating the anode-free configuration is a powerful tool to develop electrolytes not only for HVLMBs but also for HVLIBs. Anode-free cell configuration can be scaled up as a tool to design electrolytes within short period of time and less cost in industrial level. B Thirumalraj, TT Hagos, CJ Huang, MA Teshager, JH Cheng, WN Su*, and BJ Hwang*, “Nucleation and Growth Mechanism of Lithium Metal Electroplating,” Amer. Chem. Soc., 141, 18612-23 (2019)TT Hagos, WN Su*, CJ Huang, B Thirumalraj, SF Chiu, LH Abrha, TM Hagos, HK Bezabh, GB Berhe, WA Tegegne, JY Cherng, YW Yang, BJ Hwang*, “Developing High-Voltage Carbonate-Ether Mixed Electrolyte via Anode-Free Cell Configuration”, Power Sources, 461, 228053 (2020).