Enhancing the electrochemical performance of next-generation 5 V class Li-ion batteries using LiPF6/LiBOB mixed salt electrolyte

Modification of LiPF6-based electrolytes by simply combining two lithium salts to obtain a mixed electrolyte has been demonstrated as a potential strategy for the next-generation 5 V class lithium-ion battery, hindered by electrolyte decomposition and transition metal dissolution. In this study, LiPF6/LiBOB mixed salt electrolyte with different LiBOB content (10 and 20) in EC/DEC/DMC at a ratio of 1:1:1 (v/v) was tested in the high-voltage LiNi0.5Mn1.5O4 (LNMO) cathode materials to optimize their electrochemical performances. The mixed salt electrolyte performed higher ionic conductivity and better stability window than the baseline LiPF6 electrolyte. A series of electrochemical measurements, including EIS, CV, and CD, are performed in the half-cell configuration with Li-metal. LiPF6 electrolytes with 10 LiBOB showed higher discharge capacity up to 133.5 mAh g-1, better cycle stability up to 1C, and remained stable after 25 cycles. The improved performance of the mixed salt electrolyte can be attributed to the surface-forming ability of LiBOB to provide a stable cathode-electrolyte interphase (CEI) layer. In our finding, the synergistic effect between LiPF6 and LiBOB has a certain optimal ratio in which the higher ratio of up to 20 tends to decrease the overall electrochemical performance of the high-voltage LNMO cathode. © 2024 Universidad Nacional Autonoma de Mexico. All rights reserved.