Multifunctional Electrolyte Additive for High-Nickel LiNi0.8Co0.1Mn0.1O2 Cathodes of Lithium-Metal Batteries

LiNi0(0.8)Co(0.1)Mn(0.1)O(2) (NCM811) isperceived as a promising cathode material in lithium-ionbatteries for its high specific capacity and low cost. However, thecatalytic surface between the cathode and electrolyte leads to intensiveinterfacial reactions and gas generation, ultimately causing rapidcapacity fading and a great threat to the safety performance of thebattery, which hinders its applications at high voltages. Herein,ethoxy(pentafluoro)cyclotriphosphazene (PFPN) as the electrolyte additiveis applied to alleviate the above problems by constructing a solidelectrolyte interphase on the cathode and anode. PFPN can be decomposedpreferentially over basic electrolytes to shape the thin and stableinterface film between the electrolyte and NCM811 cathode for restrainingthe production of gas and the corrosion of NCM811. The wettabilityof the separator can be enhanced by PFPN to promote uniform Li deposition.Also, PFPN has a flame-retardant effect due to its phosphoronitrilefunctional group. Moreover, the Li||Li symmetrical cells can achievelong-cycling stability with the PFPN-electrolyte (cycling performanceof 800 h at 0.5 mA cm(-2)). Last, the capacity retentionof NCM811||Li reaches 89.5% after 200 cycles at 1 C and 4.5 V.

Automated summary

In this study, ethoxy(pentafluoro)cyclotriphosphazene (PFPN) was used as an electrolyte additive to construct a stable electrolyte interphase, which could suppress gas generation and cathode corrosion in lithium-ion batteries. The addition of PFPN also improved the wettability of the separator and exhibited a flame-retardant effect.