Construction of Localized High-Concentration PF6- Region for Suppressing NCM622 Cathode Failure at High Voltage

High-voltage Li||LiNi0.6Co0.6Mn0.2O2 (NCM622) batteries have obtained great interest owing to their high energy density. However, some obstacles hinder their practical applications, e.g., the structural failure of NCM622 and corrosion of the Al current collector, which lead to limited cycling life. Herein, an electrolyte additive strategy is proposed for constructing localized high-concentration PF6- zone near the cathode to form an efficient cathode electrolyte interphase (CEI) for protecting NCM622 and preventing Al current collector from the corrosion. Potassium 1,1,2,2,3,3-hexafluoropropane-1,3-disulfonimide is used as the additive to regulate the sheath structure of Li+ solvation to force PF6- anions away from the solvated Li+. During the charge process, the nonsolvated PF6- anions gather on NCM622 surface to form a localized high-concentration PF6- zone to facilitate the formation of F-rich CEI on NCM622 for protecting its structural stability and Al current collector.

Automated summary

In this study, an electrolyte additive strategy is proposed to protect NCM622 and prevent corrosion of the Al current collector. By forming a localized high-concentration PF6- zone near the cathode, an efficient cathode electrolyte interphase (CEI) is formed, improving the cycling life of high-voltage Li||LiNi0.6Co0.6Mn0.2O2 (NCM622) batteries.