High energy density lithium-ion batteries using Ni-rich cathode(such as LiNi0.6Co0.2Mn0.2O2) suffer from severe capacity decay.P-toluenesulfonyl fluoride(pTSF) has been investigated as a novel film-forming electrolyte...High energy density lithium-ion batteries using Ni-rich cathode(such as LiNi0.6Co0.2Mn0.2O2) suffer from severe capacity decay.P-toluenesulfonyl fluoride(pTSF) has been investigated as a novel film-forming electrolyte additive to enhance the cycling performances of graphite/LiNi0.6Co0.2Mn0.2O2 pouch cell.In comparison with the baseline electrolyte,a small dose of pTSF can significantly improve the cyclic stability of the cell.Theoretical calculations together with experimental results indicate that pTSF would be oxidized and reduced to construct protective interphase film on the surfaces of LiNi0.6Co0.2Mn0.2O2 cathode and graphite anode,respectively.These S-containing surface films derived from pTSF effectively mitigate the decomposition of electrolyte,reduce the interphasial impedance,as well as prevent the dissolution of transition metal ions from Ni-rich cathode upon cycling at high voltage.This finding is beneficial for the practical application of high energy density graphite/LiNi0.6Co0.2Mn0.2O2 cells.展开更多
The layered LiNi0.6Co0.2-xMn0.2MgxO2 （x=0.00,0.03,0.05,0.07） cathode materials were prepared by a co-precipitation method.The properties of the Mg-doped LiNi0.6Co0.2Mn0.2O2 were investigated by X-ray diffraction （...The layered LiNi0.6Co0.2-xMn0.2MgxO2 （x=0.00,0.03,0.05,0.07） cathode materials were prepared by a co-precipitation method.The properties of the Mg-doped LiNi0.6Co0.2Mn0.2O2 were investigated by X-ray diffraction （XRD）,scanning electron microscopy （SEM）,and electrochemical measurements.XRD studies showed that the Mg-doped LiNi0.6Co0.2Mn0.2O2 had the same layered structure as the undoped LiNi0.6Co0.2Mn0.2O2.The SEM images exhibited that the particle size of Mg-doped LiNi0.6Co0.2Mn0.2O2 was finer than that of the undoped LiNi0.6Co0.2 Mn0.2O2 and that the smallest particle size is only about 1μm.The Mg-doped LiNi0.6Co0.2Mn0.2O2 samples were investigated on the Li extraction/insertion performances through charge/discharge,cyclic voltammogram （CV）,and electrochemical impedance spectra（EIS）.The optimal doping content of Mg was that x= 0.03 in the LiNi0.6Co0.2-xMn0.2MgxO2 samples to achieve high discharge capacity and good cyclic stability.The electrode reaction reversibility and electronic conductivity was enhanced,and the charge transfer resistance was decreased through Mg-doping.The improved electrochemical performances of the Mg-doped LiNi0.6Co0.2Mn0.2O2 cathode materials are attributed to the addition of Mg 2＋ ion by stabilizing the layer structure.展开更多
基金supported by the National Natural Science Foundation of China (21573080)the Guangdong Program for Support of Distinguished Young Scholar (2017B030306013)the Science and Technology Planning Project of Guangdong Province (2017B090901020)。
文摘High energy density lithium-ion batteries using Ni-rich cathode(such as LiNi0.6Co0.2Mn0.2O2) suffer from severe capacity decay.P-toluenesulfonyl fluoride(pTSF) has been investigated as a novel film-forming electrolyte additive to enhance the cycling performances of graphite/LiNi0.6Co0.2Mn0.2O2 pouch cell.In comparison with the baseline electrolyte,a small dose of pTSF can significantly improve the cyclic stability of the cell.Theoretical calculations together with experimental results indicate that pTSF would be oxidized and reduced to construct protective interphase film on the surfaces of LiNi0.6Co0.2Mn0.2O2 cathode and graphite anode,respectively.These S-containing surface films derived from pTSF effectively mitigate the decomposition of electrolyte,reduce the interphasial impedance,as well as prevent the dissolution of transition metal ions from Ni-rich cathode upon cycling at high voltage.This finding is beneficial for the practical application of high energy density graphite/LiNi0.6Co0.2Mn0.2O2 cells.
基金Funded by the Scientific Research Fund of Hunan Education Department(10C0294)
文摘The layered LiNi0.6Co0.2-xMn0.2MgxO2 （x=0.00,0.03,0.05,0.07） cathode materials were prepared by a co-precipitation method.The properties of the Mg-doped LiNi0.6Co0.2Mn0.2O2 were investigated by X-ray diffraction （XRD）,scanning electron microscopy （SEM）,and electrochemical measurements.XRD studies showed that the Mg-doped LiNi0.6Co0.2Mn0.2O2 had the same layered structure as the undoped LiNi0.6Co0.2Mn0.2O2.The SEM images exhibited that the particle size of Mg-doped LiNi0.6Co0.2Mn0.2O2 was finer than that of the undoped LiNi0.6Co0.2 Mn0.2O2 and that the smallest particle size is only about 1μm.The Mg-doped LiNi0.6Co0.2Mn0.2O2 samples were investigated on the Li extraction/insertion performances through charge/discharge,cyclic voltammogram （CV）,and electrochemical impedance spectra（EIS）.The optimal doping content of Mg was that x= 0.03 in the LiNi0.6Co0.2-xMn0.2MgxO2 samples to achieve high discharge capacity and good cyclic stability.The electrode reaction reversibility and electronic conductivity was enhanced,and the charge transfer resistance was decreased through Mg-doping.The improved electrochemical performances of the Mg-doped LiNi0.6Co0.2Mn0.2O2 cathode materials are attributed to the addition of Mg 2＋ ion by stabilizing the layer structure.
