Ni-rich lithium nickel–cobalt-manganese oxides(NCM) are considered the most promising cathode materials 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(CaSO_(4), CSO), in an efficient one step method to increase the cycling performance of Ni-rich NCM cathode materials. Thermal treatment of LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811) cathode materials with a CSO precursor allows the formation of an artificial Ca-and SO_(x)-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 transform infrared(FTIR) spectroscopy analyses, and the process 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 of90.0%, 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.
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机译:Lijun WU, Yu ZHANG, Bingjiang LI, Pengxiang WANG, Lishuang FAN, Naiqing ZHANG, Kening SUN Fabrication of layered structure VS_4 anchor in 3D graphene aerogels as a new cathode material for lithium ion batteries