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
Nickel(Ni)-rich layered materials have attracted considerable interests as promising cathode materials for lithium ion batteries(LIBs)owing to their higher capacities and lower cost.Nevertheless,Mn-rich cathode materi...Nickel(Ni)-rich layered materials have attracted considerable interests as promising cathode materials for lithium ion batteries(LIBs)owing to their higher capacities and lower cost.Nevertheless,Mn-rich cathode materials usually suffer from poor cyclability caused by the unavoidable side-reactions between Ni^4+ions on the surface a nd electrolytes.The design of gradient concentration(GC)particles with Ni-rich inside and Mn-rich outside is proved to be an efficient way to address the issue.Herein,a series of LiNi0.6Co0.2Mn0.2O2(LNCM 622)materials with different GCs(the atomic ratio of Ni/Mn decreasing from the core to the outer layer)have been successfully synthesized via rationally designed co-precipitation process.Experimental results demonstrate that the GC of LNCM 622 materials plays an important role in their microstructure and electrochemical properties.The as-prepared GC3.5 cathode material with optimal GC can provide a shorter pathway for lithium-ion diffusion and stabilize the near-surface region,and finally achieve excellent electrochemical performances,delivering a discharge capacity over 176 mAh·g^-1 at 0.2 C rate and exhibiting capacity retention up to 94%after 100 cycles at 1 C.T h e rationally-designed co-precipitation process for fabricating the Ni-rich layered cathode materials with gradient composition lays a solid foundation for the preparation of high-performance cathode materials for LIBs.展开更多
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.
基金the financial support of the National Natural Science Foundation of China(Grant Nos.91834301,91534102 and 21271058)Science and Technology Project of Anhui Province(Nos.201903a05020021 and 17030901067).
文摘Nickel(Ni)-rich layered materials have attracted considerable interests as promising cathode materials for lithium ion batteries(LIBs)owing to their higher capacities and lower cost.Nevertheless,Mn-rich cathode materials usually suffer from poor cyclability caused by the unavoidable side-reactions between Ni^4+ions on the surface a nd electrolytes.The design of gradient concentration(GC)particles with Ni-rich inside and Mn-rich outside is proved to be an efficient way to address the issue.Herein,a series of LiNi0.6Co0.2Mn0.2O2(LNCM 622)materials with different GCs(the atomic ratio of Ni/Mn decreasing from the core to the outer layer)have been successfully synthesized via rationally designed co-precipitation process.Experimental results demonstrate that the GC of LNCM 622 materials plays an important role in their microstructure and electrochemical properties.The as-prepared GC3.5 cathode material with optimal GC can provide a shorter pathway for lithium-ion diffusion and stabilize the near-surface region,and finally achieve excellent electrochemical performances,delivering a discharge capacity over 176 mAh·g^-1 at 0.2 C rate and exhibiting capacity retention up to 94%after 100 cycles at 1 C.T h e rationally-designed co-precipitation process for fabricating the Ni-rich layered cathode materials with gradient composition lays a solid foundation for the preparation of high-performance cathode materials for LIBs.
