Constructing sulfur-rich interphase to promote the cycle stability of graphite/LiNi0.8Co0.1Mn0.1O2 pouch battery at elevated temperature

Abstract

Lithium-ion batteries (LIBs) with LiNi0.8Co0.1Mn0.1O2 (NCM811) cathodes have a high energy density, but their long-cycle performance, especially at high temperature, should still be improved due to the instability of the NCM811 cathode-electrolyte interphase. In this work, 2, 2, 2-Trifluoroethyl p-Toluenesulfonate (TPTS) is introduced as a functional film-forming electrolyte additive design to improve the long-term stability of graphite/NCM811 batteries. The preferential redox reactions of TPTS molecules play a pivotal role in fostering the creation of a sulfur-riched interphase, characterized by low impedance. This interphase works to fortify the interfacial structure, effectively inhibiting the dissolution of transition metal ions. Therefore, in comparison to the graphite/NCM811 pouch batteries lacking additive, TPTS enhance the long-cycle capacity retention from 47 % to 80 % after 450 cycles at 45 °C. What's more, TPTS suppresses outgassing and demonstrates enhanced capacity maintenance for the battery even after storage at 60 °C. This work not only demonstrates the stabilizing impacts of TPTS on the electrode-electrolyte interphase and its enhancement of cycling performance at elevated temperatures but also introduces a novel approach for the practical utilization of functional electrolytes matching high-nickel LIBs.