Ni-rich lithium nickel-cobalt-manganese oxides(NCM)are considered the most promising cathode mate-rials for lithium-ion batteries(LIBs);however,relatively poor cycling performance is a bottleneck preventing their widespread use in energy systems.In this work,we propose the use of a dually functionalized surface modifier,calcium sulfate(CaSO4,CSO),in an efficient one step method to increase the cycling performance of Ni-rich NCM cathode materials.Thermal treatment of LiNi0.8Co0.1Mn0.1O2(NCM811)cathode materials with a CSO precursor allows the formation of an artificial Ca-and SOx-functionalized cathode-electrolyte interphase(CEI)layer on the surface of Ni-rich NCM cathode materials.The CEI layer then inhibits electrolyte decomposition at the interface between the Ni-rich NCM cathode and the electrolyte.Successful formation of the CSO-modified CEI layer is confirmed by scanning electron microscopy(SEM)and Fourier trans-form infrared(FTIR)spectroscopy analyses,and the pro-cess does not affect the bulk structure of the Ni-rich NCM cathode material.During cycling,the CSO-modified CEI layer remarkably decreases electrolyte decomposition upon cycling at both room temperature and 45℃,leading to a substantial increase in cycling retention of the cells.A cell cycled with a 0.1 CSO-modified(modified with 0.1％CSO)NCM811 cathode exhibits a specific capacity retention of 90.0％,while the cell cycled with non-modified NCM811 cathode suffers from continuous fading of cycling retention(74.0％)after 100 cycles.SEM,electrochemical impedance spectroscopy(EIS),X-ray photoelectron spectroscopy(XPS),and inductively coupled plasma mass spectrometry(ICP-MS)results of the recovered electrodes demonstrate that undesired surface reactions such as electrolyte decomposition and metal dissolution are well controlled in the cell because of the artificial CSO-modified CEI layer present on the surface of Ni-rich NCM811 cathodes.