Lithium bisoxalatodifluorophosphate (LiBODFP) as a multifunctional electrolyte additive for 5 V LiNi0.5Mn1.5O4-based lithium-ion batteries with enhanced electrochemical performance

Abstract

Lithium bisoxalatodifluorophosphate (LiBODFP) is a promising multifunctional lithium salt-type electrolyte additive used to enhance the performance of 5 V LiNi_0.5Mn_1.5O₄ (LNMO)-based lithium-ion batteries (LIBs). Compared to cells without the additive, the cycling retention of the LNMO/Li half cells with 1.0% LiBODFP was improved from 77.6% to 93.7% at a 1C rate after 300 cycles. The capacity retention of the high voltage LNMO/graphite full cells with LiBODFP reached 82% at a 0.5C rate after 100 cycles, which was much higher than that of the cells without the additive (50%). It is shown that the LiBODFP can be preferentially oxidized and reduced to form robust interface films with low resistance and high conductivity on the surfaces of LNMO cathodes and graphite anodes, respectively. The LiBODFP-derived interface film can protect the cathode and anode materials, alleviate the decomposition of the electrolyte, and prevent the dissolution of metal ions from the LNMO cathode and their deposition on the graphite surface. This work provides an effective strategy for developing a functional electrolyte that matches the requirement of LNMO-based batteries with a high-voltage window and enhanced performance.