Lithium Bis(fluorosulfony)imide-Lithium Hexafluorophosphate Binary-Salt Electrolytes for Lithium-Ion Batteries: Aluminum Corrosion Behaviors and Electrochemical Properties

Abstract Aluminum corrosion behaviors and electrochemical properties of Lithium bis(fluorosulfony)imide (LiFSI)‐lithium hexafluorophosphate (LiPF 6 ) binary‐salt electrolytes containing mixtures of LiFSI and LiPF 6 (with a total salt content of 1.2 mol L −1 ) with different molar ratios in EC/EMC (3:7, by vol.) solutions are systematically investigated. Our experimental results from cyclic voltammetry, scanning electron microscopy (SEM), chronoamperometry and the charge‐discharge measurements of Li/LiNi 1/3 Co 1/3 Mn 1/3 O 2 half‐cells demonstrate that the LiFSI‐LiPF 6 binary‐salt electrolytes with the LiFSI concentrations lower than 0.3 mol L −1 exhibit not only passivating aluminum current collectors at 4.3 V vs. Li + /Li, but also improved cycling performance. Meanwhile, Artificial Graphite/LiNi 1/3 Co 1/3 Mn 1/3 O 2 (AG/NMC111) pouch cells made with the LiFSI (0.2) ‐LiPF 6 (1.0) electrolyte with the LiFSI concentration of 0.2 mol L −1 display an excellent cycling stability with 93.9% capacity retention at 1 C rate after 360 cycles, and enhanced capacity retention at −20 °C, 60 °C and after 55 °C storage for 30 days compared to cells with 1.2 mol L −1 LiPF 6 /EC‐EMC conventional electrolyte. This work confirms that binary‐salt electrolytes system, such as LiFSI‐LiPF 6 , may be a promising method to enhance the longevity and storage properties of Li‐ion batteries.