High-performance lithium-ion batteries combined with bi-functionalized electrolyte additive and nickel-rich layered oxides

Nickel-rich layered oxide-based cathode materials have received significant attention, however, relatively unstable cycling performance due to poor surface stability restricts their widespread use in the energy industry. The addition of a sulfone and amine group-based dual functionalized task-specific additive, N,N,N,N-tetraethylsulfamide (NTESA), is proposed to ultimately improve the interfacial stability of Ni-rich cathode materials. Electrochemical oxidation of NTESA deposits sulfone and aminehybridized cathode-electrolyte interphase layers on the surface of a nickel-rich cathode at about 4.0 V (vs. Li/Lithorn), which effectively inhibits electrolyte decomposition and lowers the fluoride concentration in the cell. The cell cycled NTESA-controlled electrolyte then exhibits 86.1% retention (162.0 mA h g(-1)) at normal cutoff potentials and improved cycling performance (63.2% retention, 126.2 mA h g(-1)) at high charging potentials (4.5 V, vs. Li/Lithorn) compared to the cell cycled with the standard electrolyte, which exhibits 61.8% retention (117.5 mA h g(-1)) and 48.5% retention (98.2 mA h g(-1)) at normal cutoff and high charging potentials, respectively. Based on systematic studies combined with the fundamental reactivity of NTESA and spectroscopic analyses for cycled cells by scanning electron microscopy, electrochemical impedance spectroscopy, X-ray photoelectron spectroscopy, and inductively coupled plasma-mass spectrometer, NTESA effectively improves both the surface stability of nickel-rich cathode and the interfacial stability of the graphite anode, leading to better electrochemical performance. (c) 2020 Elsevier B.V. All rights reserved.